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Milica, Samardžić. "Vremensko i prostorno rasprostranjivanje zagađivača u slivu Velike Morave." Phd thesis, Univerzitet u Novom Sadu, Poljoprivredni fakultet u Novom Sadu, 2013. http://dx.doi.org/504.5(043.3).
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Na osnovu podataka o hidrološkim i parametrima kvaliteta sa 28 mernih profila u slivuVelike, Južne i Zapadne Morave od 2000. do 2009. godine, u radu je analizirano prostorno ivremensko rasprostranjivanje zagađujućih materija duž analiziranih vodotoka, kao i uticajpoznatih izvora zagađenja na kvalitet vode u vodotocima. U cilju ocene mogućnostipredviđanja vrednosti nekih od parametara kvaliteta u analiziranim vodotocima, statističkomanalizom obuhvaćeni su podaci sa 5 mernih profila, za koje su postavljeni modeli regresioneanalize za predikciju sadržaja rastvorenog kiseonika, koncentracije suspendovanih materija,koncentracije orto-fosfata, vrednosti HPK i vrednosti BPK5, a na osnovu vrednosti proticaja ivremenske komponente – meseca u godini u kome je vršeno merenje.On the basis of data on hydrological and water quality parameters from 28 measure points inthe river basins of Velika Morava, Južna Morava and Zapadna Morava, during ten yearsperiod from 2000. to 2009., this work analyzes spatial and temporal dispersal of pollutantsalong the observed watercourses, as well as the effect of known sources of pollution to thewater quality. In order to estimate the possibility for predicting of some water qualityparameters (concentration of dissolved oxygen, concentration of suspended matters,concentration of o-phosphates, COD and BOD5) values, based on value of flow and timecomponent (month of the year in which the measurement was performed), for 7 measurepoints there are defined statistical regression models.
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Dragana, Stamenov. "Karakterizacija mikoroorganizama promotora rasta i njihovo preživljavanje u rizosferi engleskog ljulja." Phd thesis, Univerzitet u Novom Sadu, Poljoprivredni fakultet u Novom Sadu, 2014. http://dx.doi.org/579:573.4:631.559(043.3).
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PGP mikroorganizmi (Plant Growth Promoting) su predmet mnogobrojnih istraživanja, čiji je glavni cilj pronalaženje adekvatnog načina njihove primene u poljoprivredi, hortikulturi, šumarstvu i zaštititi životne sredine. Cilj ovih istraživanja bio je izolacija i karakterizacija mikroorganizama sa PGP svojstvima iz rizosfere engleskog ljulja, ispitivanje sposobnosti njihovog preživljavanja nakon unošenja u zemljište, kao i praćenje uticaja njihove primene na parametre prinosa i mikrobiološku aktivnost u rizosferi biljke. Karakterizacija izolata roda Pseudomonas, Bacillus i Streptomyces obuhvatila je određivanje fizioloških, biohemijskih i PGP osobina. Uticaj introdukcije odabranih izolata i gljive Trichoderma asperellum na brojnost i mikrobiološku aktivnost u rizosferi engleskog ljulja, određivan je standardnim metodama na selektivnim hranljivim podlogama, a dehidrogenazna aktivnost spektrofotometrijskom metodom. U laboratorijskim uslovima ispitivan je efekat primene izolata na klijavost, dužinu korenka i stabaoca klice semena engleskog ljulja. U toku godine, uzimana su tri otkosa i pri tome su određivani dužina nadzemnog dela i korena biljke (cm) i prinos zelene i suve materije nadzemnog dela biljke po otkosu (t/ha). Na osnovu morfoloških, fiziološko-biohemijskih, kao i PGP osobina koje su izolati pokazali, te na osnovu rezultata mnogobrojnih dosadašnjih istraživanja, može se zaključiti da izolati P1 i P9 pripadaju vrsti Pseudomonas putida, izolat P12 Pseudomonas fluorescens, izolati B1, B3 i B6 vrsti Bacillus subtilis, a izolati A1, A2, A3 rodu Streptomyces. Brojnost pojedinih sistematskih i fizioloških grupa mikroorganizama kao i enzimatska aktivnost u rizosferi engleskog ljulja, zavisila je od primenjenih inokulanata. Primena izolata Pseudomonas sp. P12 pozitivno je uticala na povećanje ukupnog broja mikroorganizama, brojnost gljiva, aminoheterotrofa i aktinomiceta. Izolat Bacillus sp. B1 uticao je na povećanje ukupnog broja mikroorganizama, brojnosti gljiva i azotobaktera. Primena izolata Streptomyces sp. A3 dovela je do povećanja broja aktinomiceta i oligonitrofila, dok je primena Trichoderma asperellum uticala pozitivno na povećanje broja aminoheterotrofa i azotobaktera. Primena izolata Pseudomonas sp. P12 i Streptomyces sp. A3 imala je najveći efekat na dehidrogenaznu aktivnost. Inokulacija je imala pozitivan uticaj na klijavost, svežu i suvu masu biljke, visinu i dužinu korena biljaka. Primena gljive Trichoderma asperellum i izolata Streptomyces sp. A3 delovala je pozitivno na klijavost, dužinu korenka i stabaoca klice. U proseku, najbolji efekat na prinos sveže i suve materije, kao i na visinu nadzemnog dela i dužinu korena biljke, imala je primena izolata Pseudomonas sp.P12 i Bacillus sp. B1.U proizvodnji krmnih trava mikroorganizmi još nisu našli značajniju praktičnu primenu iako je veći i kvalitetniji prinos jedan od ciljeva stočarske proizvodnje. Rezultati ovih istraživanja su pokazali da se primenom mikroorganizama mogu postići pozitivni efekti i u proizvodnji engleskog ljulja. Zbog toga je veoma značajno da se vrše dalja ispitivanja uzajamnog odnosa primenjenih mikroorganizama i engleskog ljulja u poljskim uslovima, kako bi se optimizirao način i vreme primene inokulanataPGP microorganisms (Plant Growth Promoting) have been the subject of many research projects, whose main goal is to find appropriate methods of their use in agriculture, horticulture, forestry and environmental protection. The aim of this study is the isolation and characterization of microorganisms with PGP characteristics from the rhizosphere of perennial ryegrass, testing their ability to survive after entering the soil, and monitoring the impact of their application on yield parameters and microbial activity in the rhizosphere of plants. Characterization of Pseudomonas, Bacillus and Streptomyces included determination of the physiological, biochemical and PGP characteristics. Impact of the introduction of selected isolates and fungi Trichoderma asperellum on quantity and microbial activity in the rhizosphere of ryegrass was determined by using the standard method of selective media; dehydrogenase activity by the spectrophotometric method. The effects of the implementation of isolates on germination, seedling length sprouts seeds of perennial ryegrass were studied under laboratory conditions. During the year, three cuttings were taken. At each of the three cuttings, length of stem and roots of plants (cm) and yields of fresh and dry matter of the plant (t / ha) were measured.Based on morphological, physiological and biochemical characteristics and PGP characteristics observed in the isolates, and based on the results of many previous studies, it can be concluded that (1) P1 and P9 isolates belong to the species Pseudomonas putida, (2)Pseudomonas fluorescens P12 isolate, isolates of B1, B3, B6, belong to the species Bacillus subtilis, and (3) A1, A2 and A3 isolates belong to the ordo Streptomyces. The quantity of systematic and physiological groups of microorganisms and enzymatic activity in the rhizosphere of ryegrass depended on the applied inoculants. Application of Pseudomonas sp. P12 had positive effects on increasing the total number of microorganisms, fungi, aminoheterotrophs and actinomycetes. Isolate Bacillus sp. B1 affected the increase of the total number of micro-organisms in the fungi and Azotobacter. Application of Streptomyces sp. isolates A3 led to an increase in the number of actinomycetes and oligonitrophyls, while the application of Trichoderma asperellum had positive impact on increasing the number aminoheterotrophs and Azotobacter. Application of Pseudomonas sp. P12 and Streptomyces sp. A3 had the greatest effect on dehydrogenase activity. Inoculation had a positive effect on germination, fresh and dry weight of plant, height and rootlength of plants. Introduction of fungus Trichoderma asperellum and Streptomyces sp. A3 isolate acted positively on germination, length of seedling of germs. On average, the best effects on the yield of fresh and dry matter, the height of the stem of the plant and the length of the root were attained by the application of Pseudomonas sp.P12 and Bacillus sp. B1 isolates. Microorganisms have not yet found significant practical use in the production of forage grasses, even though more qualitative yield has been sought in livestock production. The results of this study demonstrate that positive results in the production of perennial ryegrass can be achieved by the use of microorganisms. Therefore, it is very important to carry out further studies of the relationship between applied microorganisms and ryegrass under field conditions in order to optimize the method and time of application of inoculants.
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Martin, Garcia Ignacio. "Sludge free and energy neutral treatment of sewage." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/6530.
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Anaerobic biological processes have been recognized as the most suitable pathway towards sustainable wastewater treatment due to the lower energy required and the lower amounts of biosolids generated when compared to conventional aerobic technologies. The difficulties experienced with the implementation of anaerobic reactors for the treatment of low strength wastewater at low temperatures are related to the deterioration of treatment capacity and effluent quality due to inefficient removal of colloidal matter and biomass washout. Membrane technology can overcome the limitation of anaerobic bioreactors since they retain not only solids but also colloidal and high molecular weight organics. This thesis explores the potential of anaerobic membrane bioreactors as core technology for mainstream wastewater treatment. The impacts of seed sludge, temperatures and bioreactors configuration on treatment efficiency and membrane performance as well as nutrient removal using ion exchange resins are investigated. Cont/d.
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Ramos, Elsa Dolores Chacin. "Treatment characteristics of two phase anaerobic system using an UASB reactor." Thesis, University of Birmingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633074.
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During this project, the treatment of a simulated wastewater from soluble starch by a two-phase anaerobic system using an UASB reactor was examined under mesophilic conditions. Prior to seeding the reactors, the pregranulated sludge which was to be used as the inoculum for the acidogenic reactor, was acidified to pH 4.3, using a mixture of volatile fatty acids, to improve the spatial bacteria separation in the system. The two-phase system was studied, first under different organic loads and secondly, in terms of its resistance to the addition of heavy metals. For the first experimetal studies, different organic load were applied to the system, and changes to the microbial ecology of the acidogenic and the methanogenic phase was assessed. The biomass in the methanogenic reactor was mainly composed of fluorescent methanogenic bacteria. In the acidogenic reactor after the start-up period elapsed, no fluorescent bacteria were observed. Two different runs were performed and for each individual run, different OLR were used. For the first run, the organic loads applied to the system were from 3.83 to 30.63 kg COD/m3d, this gave organic loads for the methanogenic reactor of between 4.56 to 44.3 kg COD/m3d. In the second run, the OLR used were from 10 to 16.6 kg COD/m3d for the overall system, and from 13 to 23.35 kg COD/m3d for the methanogenic reactor. Organic loads greater than 15 kg COD/m3d, caused biomass wash-out from both the acidogenic and methanogenic reactor. The best COD removal efficiencies and gas production rates were achieved by the system under OLR of 13.31 kg COD/m3d, with pCOD removal efficiency of 95 % and methane production of 80.2 %. The biogas production was 0.33 m3CH4/kg COD removed. Under high applied organic load, the microbial population of the methanogenic reactor changed, and filamentous foaming bacteria were isolated both from the sludge and the foam that was produced. The species found to be responsible for the foam formation in the anaerobic methanogenic reactor was Microthrix parvicella, which was identified using the Neisser test and Scanning Electron Microscopy (SEM). For the second part of this experimental work, copper and lead were used as toxic elements. These two heavy metals were choose due to the fact that they are subproducts of many industries and can cause significant environmental problems. Copper and lead were used as the acetates and chlorides to study the effect of these heavy metals when they were combined with different anions. It was found that the combination of copper and lead as chlorides were more toxic to the anaerobic treatment than when they were present as acetate. Also, it was found that the two heavy metals used were toxic to the acidogenic phase and not to the methanogenic phase.
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Thompson, Andrew. "The fate and removal of pharmaceuticals during sewage treatment." Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/8539.
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Pharmaceuticals, personal care products and their metabolites are contiuously entering the environment through many route, especially from the effluent of sewage treatment plants. The aim of this work was to examine the fate and removal of pharmaceuticals during sewage treatment, and establish ways in which current sewage treatment technologies could be optimised to improve removal. Based on an analysis of pharmaceutical usage and environmental effects, four compounds were selected for further study (triclosan, tetracycline, carbamazepine, and caffeine). Reliable analytical methods were developed, using HPLC-UV, to detect these compounds in sewage samples. The amounts of removal of the four compounds were quantified using laboratory sorption and biodegradation tests. Both tetracycline and triclosan were shown to be readily biodegradable, and to sorb strongly to biomass, although sorption occurred at different rates. Caffeine degraded rapidly, but did not sorb to biomass, whilst carbamazepine did not sorb or biodegrade. Grab samples were taken before and after every major process unit at four sewage treatment plants (STPs). Although tetracycline was not detected in any samples, triclosan was measured at concentrations up to 5115 ng 1-1, caffeine was measured at concentrations up to 82,300 ng1-1, and carbamazepine was measured at concentrations up to 1461 ng 1-1. This is the first time carbamazepine and caffeine concentrations have been reported in UK sewage. The grab samples showed that a wide range of pharmaceutical effluent concentrations can be enough to cause immediate harm (i.e. death) to aquatic organisms. However, there is insufficient infomation to determine whether exposure to these low concentrations, typically around PNEC levels, may have an effect over a long period of time. Further composite sampling conducted at one STP generated data, modelled using Toxchem+, which demonstrated how variations in a wide range of parameters were correlated with the removal of pharmaceuticals. These showed that whilst sludge age may be the most important parameter, pH, temperature, hydraulic retention time, and chemical oxygen demand could have a critical effect on the removal of pharmaceuticals. Several ways of optimising sewage treatment plants have been proposed, including pH adjustments and longer HRTs to enhance sorption, as well as a novel adaptation to activated sludge tanks incorporating two IFAS type bioreactors to enhance biodegradation. The effects of plant operating events, such as aeration failures, were also investigated. These showed that a typical length of aeration loss (four hours) could result in reduced pharmaceutical removal (through decreases in both sorption and biodegradation) for up to twelve hours. Overall, this work has shown that it may be possible to adapt current sewage treatment technology to improve removal of pharmaceuticals which sorb or biodegrade readily. With further research, these adaptations could become a viable alternatice to tertiary treatment technologies such as ozonation, granular activated carbon, or chlorine dioxide.
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Oliver, Roly. "Phthalates in wastewater : types, occurence and fate during treatment." Thesis, University of Portsmouth, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411553.
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Toki, Christina. "Evaluation of temperature phased aerobic digestion process using chicken manure as a surrogate for wastewater sludge." Thesis, University of Portsmouth, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424211.
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Forster, Scott. "Rapid assessment of bacteria in wastewater systems." Thesis, University of Exeter, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398926.
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Sani, Badruddeen Saulawa. "Modelling of pollutant adsorption by activated carbon and biochar with and without magnetite impregnation for the treatment of refinery and other wastewaters." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3595.
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This study evaluated the application of magnetised powdered activated carbons and biochars, in the removal of typical pollutants encountered in refinery and other wastewaters. Phenol, pharmaceuticals and heavy metals were chosen as representatives of priority pollutants, organic micropollutants and metals. In the sorption of the organics, there existed a strong correlation (Pearson correlation R up to 0.9990) between isotherm models’ capacity parameters and sorbents’ capacity influencing properties. In the case of the metals, the sorbents’ capacities are not dependent upon surface area and micropore volume. In some instances, the biochars have on the average about 20.45% higher uptake of the metals than the activated carbons. A general decrease in phenol uptake on the biochars with increase in pH was recorded, due to electrostatic repulsion between like charged surface and sorbates. For the activated carbons, peak phenol sorption was found within the vicinity of the pKa and point of zero charge when there is maximum electrostatic attraction between the opposite charged surface and sorbates. For the micropollutants, ibuprofen was negatively affected by an increase in pH while diclofenac sorption was not sensitive to changes in pH. Sorption of metals was found to increase with an increase in pH. Synthetic wastewater (SWW) did not have a significant impact on the sorption of the phenol and heavy metals. In the case of phenol, the highest impact, an average of just 6.15% for all sorbents was recorded. For the micropollutants, according to the linear model, there is, on the other hand, about 92 and 96% less uptake of diclofenac and ibuprofen respectively due to competition. Finally, in an equimolar solution, due to its high solubility, Zn2+ was outcompeted by Cu2+ and Pb2+ for binding to available sorption sites.
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Nguyen, Vi T. "Biofilm formation of Methanosarcina barkeri on different support materials : applications for anaerobic digestion." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/18374/.
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Biofilms are sessile microbial communities attached to a surface, and offer a multitude of benefits to various biotechnological applications, such as anaerobic digestion. Therefore, engineering systems to promote biofilm formation is becoming increasingly desirable in the biotechnology sector. This thesis aimed to promote biofilm formation from the robust model methanogen, Methanosarcina barkeri, onto polymer support materials as a strategy for optimising the anaerobic digestion of domestic wastewater in peri-urban areas. A first step in this direction was to understand the effect of the support material on the biofilm-forming capabilities of M. barkeri. Various techniques were used throughout this thesis to show that the choice of support material was an important environmental factor in triggering different physiological responses from M. barkeri during biofilm formation. DLVO modelling, surface characterisation and static adhesion assays revealed the important role of the physicochemical surface properties of M. barkeri and the six support materials for initial microbial adhesion. M. barkeri was shown to exhibit different abilities to attach to the support materials, with the type of material strongly influencing the extent of initial attachment. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential analysis and fluorescence microscopy suggested that significant modifications to the cell surface occurred in response to attachment to a favourable support material (PVC), with increased levels of cell surface polysaccharides detected in biofilms attached to PVC compared to PETG. Furthermore, microbial attachment to PVC caused a significant higher relative abundance of proteins involved in methanogenesis, metabolism, cell wall biogenesis and EPS production compared to biofilms attached to PETG. The results from this thesis suggest that M. barkeri showcases different physiological responses for biofilm formation depending on the support material. Therefore, the choice of support material is an important design parameter for retaining microbial biomass within AD reactors, and should be considered in future design frameworks for high rate anaerobic digestion.
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Wang, Moran. "Network modelling of the formation and fate of hydrogen sulfide and methane in sewer systems." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18325/.
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Hydrogen sulfide is produced by sulfate reducing bacteria, which are mainly associated with the biofilms covering the surfaces in rising mains. Sulfide control strategies commonly used such as chemical dosage are costly for long-term management. The effect of physical and hydraulic conditions of sewers on sulfide formation has been investigated in recent years. One of the key parameters in modelling the formation of hydrogen sulfide is the pipe area- volume ratio (A/V), as this indicates the relative contribution between biofilm and wastewater processes. The A/V is naturally related to the pipe diameter. A high A/V is associated with small pipe diameter, and would lead to a high contribution from the biofilms and hence the potential for high hydrogen sulfide formation. However, it would also decrease the residence time of the wastewater, which would tend to decrease the amount of hydrogen sulfide formed. Based on the results of in-sewer process modelling, this study quantifies the importance of the pipe diameter and pumping strategy for optimal design for rising mains, to minimise hydrogen sulfide production, either to improve the life time for the downstream sewer structures or to minimise the potential chemical dosing needed in the rising mains. The model results from this study show optimal diameter options for both existing rising mains in terms of minimum hydrogen sulfide formation. The sensitivity analysis on model parameter based on the case studies also indicates the most uncertain parameters and COD fractions. Methane is a problem acknowledged in some sewer networks around the world and is particularly of concern in China where sewer explosions can occur. Septic tanks are integrated parts of many Chinese sewer systems and methane is believed to be produced not only in sewer pipes, but also in septic tanks. Work has been done to look at how the anaerobic digestion model can be applied in combinations with sewer processes models to describe such a system. Model simulation results on methane formation in rising mains is similar to reported literature. The field measurements in the Chinese sewer system demonstrated high gas phase hydrogen sulfide and methane concentrations both in gravity systems and rising mains due to the surcharging sewer conditions. Future work has been proposed according to the local problems by discussing the benefits of applying sewer process and anaerobic digestion models based on this study.
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Kleemann, Rosanna. "Sustainable phosphorus recovery from waste." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809963/.
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Phosphorus (P) is an essential non-substitutable nutrient for all living organisms, but it is also a dwindling non-renewable resource. Approximately two-thirds of the world’s supply of phosphate rock is located in China, Morocco, and the USA. Phosphate rock is included in the EU list of ‘critical raw materials’ and is ranked 20th in an index of commodity price volatility. P recovery from waste water can help alleviate reliance on imported phosphate and reduce vulnerability to fluctuating prices. This project explored the options for P recovery from wastes produced across Thames Water’s waste water treatment plants (WWTPs), the main foci being sludge dewatering liquors and incineration/pyrolysis residues. The research focussed specifically on the Slough WWTP and the operation of a newly installed Ostara system for recovery of P as struvite from dewatering liquors. The Ostara process is designed to operate with centrate PO4-P concentrations above 100 mg/l; to obtain these concentrations chemical coagulant dosing in the enhanced biological nutrient removal process must be reduced. Centrate monitoring following this change showed that Fe concentrations must measure consistently below 1.5 mg/l for PO4-P concentrations to remain steadily above 100mg/l. Following these changes onsite, operational savings and revenue can be produced onsite. Significant operational and maintenance savings totalling to £113K can be made in the first year of operation of the P recovery system in Slough WWTP. Sale of P rich struvite fertiliser produces annual revenue of £20K. Moving beyond the local benefits of P recovery, national benefits of P recovery were quantified. In a national context, a total of 28±1 kt P/year can be recovered from all WWTP waste streams, reducing P fertiliser imports by 36±1%. P recovery from WWTP influent and incinerated sewage sludge ash would reduce P losses to water bodies by 22±2%. Sewage sludge may be incinerated, producing incinerated sewage sludge ash (ISSA), or alternatively pyrolysed to produce sewage sludge char (PSSC). The possibility of recovering P from these residual solids was also investigated. PSSC samples contained significantly more nitrogen and lower heavy metal concentrations than ISSA samples due to the process conditions. The % P extractions from both ISSA and PSSC plateaus at 0.6M and 0.8M H2SO4 acid concentrations, respectively, due to the formation of gypsum on the particles, so that further increase in acid concentrations does not increase P recovery. The knowledge gained through this research has been used to improve the understanding and efficiency of the P recovery system at Slough WWTP. The information learned about pyrolysis residues will be used by Thames Water to develop a novel P recovery process from PSSC. Combined, these findings can impact the industry by creating incentives and inform policies regarding P recovery.
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Al, Tahmazi Talib. "Characteristics and mechanisms of phosphorus removal by dewatered water treatment sludges and the recovery." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/105255/.
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The use of novel industrial by-products (IBPs) to remove phosphorus (P), instead of high-cost P removal techniques, is one of the sustainable solutions to protect aquatic life from excessive P discharges. One of such IBPs is dewatered drinking water treatment works sludges generating from using aluminium or iron salts as coagulant during the drinking water treatment process. Previous studies have shown that the sludges hold promise as a novel adsorbent for the removal of P from wastewaters; however, comprehensive investigation into factors affecting the P removal and the recovery is lacking. Therefore, the main aim of this study is to contribute to a mechanistic understanding of P removal and retention by dewatered water treatment sludge (DWTS), and the associated coagulant recycling and P recovery from the P-saturated sludge used as substrate in a constructed wetland system. Seventeen DWTSs were collected from different areas in the UK to study the combined effect of sludge inherent properties and solution chemistry; and the P equilibrium and kinetic adsorption behaviour using batch experiments. Results revealed that the metal content (Al, Fe, Aloxalate and Feoxalate) and specific surface area components had the most significant explanation for the variance of: (i) P-uptake at different initial P concentrations; (ii) the adsorption maxima; and (iii) the Freundlich constant. Overall, giving the combined effect of intrinsic sludge properties and solution chemistry, dewatered waterworks sludges with high reactive metal content (Al and Fe), Ca and SO42- ions, and total specific surface area, would be the best choice for P retention in practical applications. Phosphorus retention by two Al- and two Fe-DWTS were modelled under various operation conditions of hydraulic retention time and influent P concentration, using a continuous feeding system. Four design equations for P retention were developed and these successfully predicted discrete P retention, maximum P loaded to the sludge, accumulative amount of P retention, and lifespan at the required P saturation degree. The model results revealed that the lifespan of ferric sludge is about four years to reach its saturation point, if the flow rate of 190 (l/capita.d) and inflow P concentration of 5 mg/l are used. IV With regards to coagulant recycling and P recovery using electrodialysis (ED) technology, P saturation degree influenced negatively on Fe and P recovery where their percentages dropped from 70 ± 8%, 49 ± 3% to 17 ± 2, 6 ± 1% when P saturated sludge increase from 0% to 100% respectively. The normalised values of recovered Fe to permeated dissolved organic carbon (DOC) were between 29 and 290. Most of the recovered coagulants were comparable in performance with commercial coagulant in term of DOC removal (42 to 59%), Turbidity, and UV254 absorbance. Overall, the results have shown that DWTS has great potential not only for P removal but also for coagulant and P recovery. However, further research is needed before the developed models can be applied at field scale, and also to enhance the ED recovery for further benefits.
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Kim, Gwangjun. "A visible-light assisted dual purpose photoelectrochemical cell for simultaneous removal of heavy metals and organic pollutants in wastewater." Thesis, University of Nottingham, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659292.
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Water pollution is a major global issue which poses a serious threat to human health as well as the aquatic environment. In particular, dissolved heavy metal species and persistent organic pollutants (POPs) have been regarded as major problems due to their high toxicity and non-biodegradability. Adsorbents and membrane filtration are the most widely used technologies for the treatment of contaminated waste water, however the high cost and environmental implications of these technologies have encouraged a paradigm shift to the use of photocatalytic processes for wastewater treatment. In this work, an innovative photoelectrochemical process for simultaneous removal of heavy metal ions and POPs from wastewater was developed and demonstrated using a photoelectrochemical cell (PEC) with a W03 photoanode under sunlight irradiation. Synthetic wastewater samples containing 0.5 M of NaCI, 10 ppm of methylene blue (MB, organic pollutant), 500 ppm of CuCh or 500 ppm NiCh were tested as the first examples for demonstration of the principle, device and process. The results showed that upon irradiation of simulated sunlight on the photoanode, metal ions (Cu2+ and Ni2+) can be recovered as metals at the cathode. MB was simultaneously decomposed at the photoanode without using any additional chemicals. The cell voltage required for this dual purpose process was as much as 71 % or 57 % lower than that required for conventional electrodeposition of Cu or Ni respectively with an inert anode. Current efficiency for electrodeposition in the PEC could be adjusted close to 100 % depending on applied cell voltage, minimising charge loss for H2 evolution. Meanwhile, as a potential photocatalyst, CNTs/W03 hybrids were successfully synthesised by a surfactant aided sol-gel method and tested for their photocatalytic performance. It was found that the addition of CNTs to W03 by either hybridisation or mechanical mixing caused a significant drop of both photocurrent and photovoltage of W03, presumably due to the interfacial electronic structure between W03 and CNTs.
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Abubakar, Umar Alfa. "A technological model for low energy domestic wastewater treatment." Thesis, Abertay University, 2015. https://rke.abertay.ac.uk/en/studentTheses/51ee0b9e-808f-441e-8420-c2276cccbf48.
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This study evaluated the potential for efficient treatment of domestic wastewater, while satisfying energy efficiency requirements. Various treatment systems and the influences of their physical configurations and operational characteristics on wastewater treatment and energy efficiency were initially considered and evaluated. Review of literature identified high rate anaerobic systems as viable low energy systems for domestic wastewater treatment, with reported high removal of influent chemical oxygen demand (COD) and high net energy balance for the anaerobic baffled reactor (ABR). Low energy recovery is reported in literature as a limitation of anaerobic domestic wastewater treatment, and anaerobic domestic wastewater treatment systems have failed to meet effluent discharge standards, and post-treatment using aerobic processes have been recommended in order to ensure high effluent quality. Therefore, the ABR was selected as a feasible option that can be developed as the first stage of an anaerobic-aerobic low energy domestic wastewater treatment system. The literature review also identified the net energy consumption per cubic metre (m3) of treated wastewater during the treatment process as an energy efficiency evaluation criterion. Energy efficiency for domestic wastewater treatment facilities should be achieved if efficient treatment performance can be sustained at ambient temperature, instead of the fixed mesophilic temperature that is commonly adopted in anaerobic treatment processes. To identify an energy efficient design of the ABR in terms of hydraulic retention time and operational temperature, the performance efficiencies of ABR bench models were monitored at ambient temperature and 37oC at hydraulic retention times (HRT) of 48, 36, 24, 12 and 6 hours, which corresponded to organic loading rates (OLR) of 1.25, 1.67, 2.5, 5.0 and 10.0 kg COD/m3 day. 88.43, 90.00, 84.03, 77.01 and 59.35% of the influent COD (mean = 2479.50 mg/L) were removed at 48, 36, 24, 12 and 6 hour HRTs, respectively, in the 37oC bench reactor, while 70.16, 70.36 and 74.99% of the influent COD were removed at 48, 36 and 24 hour HRTs, respectively, in the ambient temperature bench reactor. Steady state performance, in the form of stable pH values, was not observed in the ambient temperature reactor at 12 hours HRT before the end of the bench experiments. Retention of influent total solids was observed to correlate to hydraulic retention time, with increase retention of total solids corresponding to increase in hydraulic retention time. Furthermore, observed total solids retention in the ambient temperature reactor were less than the total solids retention in the 37oC reactor. Anaerobic reduction of domestic wastewater sludge and the corresponding methane production were also evaluated using bio-chemical methane potential (BMP) batch assays at ambient temperature and compared to a fixed mesophilic temperature of 37oC. Low reduction of volatile solids was observed in the BMP assays, with 40% at ambient temperature compared to 56% at 37oC for primary sludge, and 22% at ambient temperature compared to 38% at 37oC for secondary sludge. Critical limitations of the anaerobic stage at ambient temperature were determined to be the biological reduction and conversion of the organic contaminants to soluble COD and volatile fatty acids (VFA). Also, achieving and maintaining steady state performance required a longer time period at ambient temperature than at 37oC, potentially due to the slow growth of the anaerobic microorganisms at ambient temperature. These limitations indicate the need for long (≥ 24 hours) retention periods for efficient operation at ambient temperature. The ABR bench models were evaluated for energy efficiency with the identified energy efficiency criteria, and the operational condition with the highest energy efficiency was determined to be 12 hours HRT at 37oC. Finally, design criteria for the anaerobic stage of the anaerobic-aerobic system were proproposed, along with a process model as a preliminary step for future process research.
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Mackley, Tim. "Design and evaluation of a novel wastewater treatment package plant." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/11185.
Full textAbstract:
The
objective of the project was to develop a novel package plant using available
process technologies that would be competitive in the domestic waste water treatment
market.
A market
analysis identified the business opportunity for Balmoral Tanks to develop a
package plant with higher treatment capability than its current product. A customer
survey and a review of Regulatory standards provided valuable input into the design
considerations for the
package plant.
A review of available
process technologies and materials of construction resulted in
the selection of a
Moving Bed Biolm Reactor (MBBR) process and High Density
Polyethylene material as the optimum design basis for the package plant.
A detailed
design exercise scoped out and specified all the components of the MBBR
package plant.
A four month duration
programme for testing the prototype at Cranfield University
facilities was devised which
satisfactorily simulated typical domestic wastewater
treatment
operating conditions. Test rig problems associated with very low ambient
temperatures were experienced in the early stages of testing and were identified and
resolved. The
prototype package plant unit subsequently operated satisfactorily and the
performance was demonstrated to meet all the wastewater constituent removal design
specifications. The MBBR process performance was shown to be consistent with
published findings of other researchers.
Novel fabrication methods
developed by Balmoral Tanks resulted in the cost of the
new MBBR
package plant being only 3% higher than that of Balmoral Tanks current
lower
specification product.
The new MBBR
package plant is shown to be a potentially very marketable domestic
wastewater treatment
product.
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Gersten, Benjamin. "A feasibility study in the use of domestic water treatment residuals to remove phosphorus from wastewater." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/103678/.
Full textAbstract:
There is growing evidence that even low levels of phosphorus (< 0.1mgL-1) entering natural water systems can cause eutrophication. Waste water treatment plants discharge over 23kT of phosphorus into UK surface waters per year. The Water Framework Directive requires that this be greatly reduced. Although many processes have been developed, they are often complex and energy intensive. This thesis aimed to assess how a novel process using dewatered water treatment works residuals (DWTR) could be engineered to maximize phosphorus removal from waste water treatment plant effluents while minimising system complexity and energy use. An extensive yearlong experiment was operated at two sites to investigate how phosphorus removal rates varied over time in relation to DWTR type, phosphorus concentration, hydraulic retention time (HRT) and scale. DWTR from eight different water treatment works were used in 35 experimental models of dimensions 0.1Ø x 1m and two meso scale beds 1x1x0.8m. The most significant factors effecting P removal rate were found to be DWTR type and media particle size. Total P removal varied between 58-95% for the 8 different DWTR over the year. Increasing particle size from 0.6-2 to 6-20mm reduced P adsorption capacity by 30% on average with 6 hours HRT and 5mgL-1 TP input. The key physical and chemical properties of the DWTR were measured to assess the effect of the parameters on the P removal ability of the media. No significant relationship (p < 0.05) between the amount of Al, Fe, Ca or Mg in the media and its P removal ability were found. An idealised adsorption system using DWTR as the media would operate with 2 to 3 beds in series with a minimum HRT of 6 hours and maximum particle size of 6mm and depth of 1m. Computer models of such a system predict >95% TP removal for over two years of operation.
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Ramirez, Sosa Dorian Roberto. "Resource recovery from co-digestion of organic waste with surplus activated sludge via the carboxylate platform." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17951/.
Full textAbstract:
Waste activated sludge (WAS) is an important residue generated from Wastewater Treatment Plants (WWTPs) with a high amount of organic and inorganic resources. In view of this, WAS management systems have changed towards improving the use of waste biomass as a feedstock for bioenergy generation and nutrient recovery and reuse. This study assessed the potential of using WAS as the main feedstock for the generation of high-value chemicals like volatile fatty acids (VFAs), via the carboxylate platform. In order to achieve that, a series of experiments were conducted with the aim to identify the main process variables controlling VFA production in batch and semi-continuous stirred tank reactors (CSTRs). In the first stage, acidogenic fermentations were run for 21 days using iodoform as an inhibitor of methanogenic bacteria, reaching VFAs yields of 0.238 g TVFAs/g TVSWAS with iodoform (CHI3) in a ratio of 6 mg CHI3/g VSS and an Organic Loading Rate (OLR) of 5 g TVSWAS/L. The second stage comprised the acidogenic fermentation of high pressure thermal hydrolysis (HPTH)-WAS under different pH conditions (4-1) with results of 0.415 g VFAs/g TVS at pH 9.0 and C/N=8.77, which emphasize the strong effect that pH has on VFA production and speciation and, on the inhibition of methane (CH4) generation. In order to improve VFAs production from HPTH-WAS, acidogenic co-fermentations at pH 9.0 were conducted using thermally pre-treated food waste and algal biomass (Chlorella vulgaris). Optimum results reported a yield of 0.496 g VFAs/g TVS at C/N=12.72 for fermentations using a blend of 25% HPTH-WAS/75% HPTH-Food waste and 25% HPTH-WAS/75% HPTH-Chlorella vulgaris with VFA yields of 0.378 g VFAs/g TVS, C/N=5.08. This suggests that HPTH pre-treatment and co-fermentation had a positive effect on the final production of VFAs despite of the C/N ratio used. Finally, experiments using semi-CSTR reactors fed with HPTH-WAS at pH 9.0 reported yields of 0.539, 0.328 and 0.364 g VFAs/g TVS for fermentors with OLRs of 0.3, 0.6 and 1.0 g TVS WAS/L·d, respectively. This suggests that increments in OLR have a null effect on VFAs production. Fermentations working with 0.3 g TVS WAS/L·d presented overall VFAs production which stoichiometrically exceeds in 31% the methane produced in AD experiments ran in this project. The OLR presented a null effect on the speciation of the VFAs as acetic acid was present in concentrations above 80% of the carboxylic acids content in all CSTR experiments. These results confirm the potential opportunities for high-value chemicals production from HPTH-WAS as part of the development of the biorefinery concept in existing WWTPs.
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Monteiro, Sílvia Patrícia Nunes. "Integration of culture- and molecular-based water quality monitoring tools to protect human health." Thesis, University of Brighton, 2017. https://research.brighton.ac.uk/en/studentTheses/ffb51e9c-1902-4926-b91a-a7be3bbc6680.
Full textAbstract:
Monitoring and improving the microbiological quality and safety of surface waters used for various purposes, including drinking water abstraction and recreation is paramount as degradation may pose a serious risk to human health and cause significant economic losses as a result of the closure of beaches and shellfish harvesting areas. With the aim of providing new knowledge and tools with which to manage more effectively faecal contamination of water resources, this study focused on three goals: 1) determining the fate and suitability of new bioindicators for virus removal during wastewater treatment; 2) elucidating the levels and sources of faecal pollution in the River Tagus (Rio Tejo) using a blend of newly-developed and existing microbial source tracking (MST) markers; and 3) critically evaluating various pretreatments to distinguish between infectious and non-infectious viruses. To this end, raw and treated wastewater were collected and tested for the presence of traditional faecal indicator bacteria (FIB), and four viral bio-indicators (namely, somatic coliphages (SC), GB124 phages, human adenovirus (HAdV) and JC Polyomavirus (JCPyV)). In order to demonstrate whether the novel bio-indicators might be suitable indicators of risk to human health, Norovirus genogroup II (NoVGII) were also analysed, in parallel. FIB, SC and GB124 phages were analysed using standardised culture methods (membrane filtration and plaque assays) and HAdV, JCPyV and NoVGII were analysed using widely used molecular (qPCR) methods. Samples of river water were collected over a thirteen-month period and analysed for both non source-specific indicators of faecal contamination (Escherichia coli (EC), intestinal enterococci (IE), and SC) and source-specific contamination markers ((GB124 phages, HAdV) and four mitochondrial DNA markers (HMMit, CWMit, PigMit and PLMit)). EC, IE, SC and GB124 phages were detected by culture methods and HAdV and mitochondrial markers were detected by molecular (qPCR) methods. Furthermore, domestic animal markers (based on the detection of mitochondrial DNA) were also developed for dog and cat and tested during the catchment study. Finally, in order to determine accurately the level of risk to human health, heat-, chlorine-, and UV-inactivated Enterovirus and Mengovirus were subjected to PCR pre-treatments using enzymatic digestion and viability dyes, in order to determine infectivity. Detection of inactivated Mengovirus (MC0) was performed by RT-qPCR and detection of inactivated Enterovirus (EntV) was performed by both RT-qPCR and cell culture. The results demonstrated that the traditional bacterial indicators (FIB) were more effectively removed during wastewater treatment than GB124 phages, SC, HAdV and JCPyV, the removal levels of which were more similar to those of NoVGII. Spearman’s correlation showed that SC and GB124 phages correlated positively with NoVGII at a relatively high level and that HAdV and EC correlated positively at a moderate level. Discriminant analysis revealed that whilst no organism could predict the presence or absence of NoVGII in treated wastewater, GB124 phages in combination with other parameters did result in higher percentages of correct classification. GB124 phages plus HAdV appeared to be good candidates as alternative indicators of enteric virus removal during wastewater treatment. Results from the catchment study demonstrated that certain sites on the River Tagus are relatively highly impacted by faecal contamination (as indicated by EC, IE and SC concentrations). Moreover, the MST markers revealed that this contamination appears to be not only of human origin, but also originates from a range of other animal sources. The HMMit marker was the most prevalent and was found at the highest mean concentrations, followed by the CWMit marker. Two-way ANOVA revealed a correlation between concentrations of non source-specific indicators (and the CWMit marker) and season. Physico-chemical parameters, such as temperature and UV radiation, were found to be related to to levels of the CWMit, EC, IE, and SC. Interestingly, rainfall levels were found to be related to concentrations within the river of the PLMit marker and of the newly-developed dog and cat markers. Weak to no correlations were found between non source-specific indicators and the various MST markers, providing further evidence that these faecal indicators were unsuitable for determining the source(s) of contamination in this study. In contrast, the relatively high sensitivity and specificity of the mitochondrial DNA markers supported their use as appropriate markers of the origin of faecal contamination in this scenario. The results from the viral infectivity study demonstrated that results of ‘viability PCR’ (involving viability dyes) of chlorine- and UV-treated viruses did not correlate with those from cell culture assay. However, data from RNase-RT-qPCR from chlorine- and UV-inactivated viruses were consistent with the cell culture assay, achieving full PCR signal reduction in several instances. Heat treatment appeared to play an important role, since a significant reduction in the RT-qPCR signal was achieved. Different pre-treatments were able to achieve full removal of RT-qPCR signal for non-infectious heat-treated EntV and MC0. Therefore, enzymatic treatment may represent a rapid and inexpensive tool for discriminating between infectious and non-infectious viruses and as such should improve understanding of risks to human health. This research has demonstrated that the currently-used methodologies and approaches to assess the potential human health impact of wastewater discharges to environmental waters are limited in their ability to predict the prevalence of important agents of human waterborne disease. Furthermore, these findings provide evidence to support the development and application of alternative and potentially more effective approaches, which could better protect human health in the future.
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Coughtrie, Andrew Robert. "Coupling hydrodynamic and biological process models for wastewater treatment." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16207/.
Full textAbstract:
This thesis considers the problem of modelling bioreactors with complex mixing and biokinetic growth based on both soluble nutrients and photosynthesis. From the results of investigations performed on the different modelling methods for nutrient and photosynthesis dependent biomass growth a method of coupling the two biokinetic models was proposed. This new photosynthesis-nutrient (PN) model was then investigated, validated and determined capable of predicting growth characteristics dependent on both nutrient and photosynthetic processes. Additionally an investigation into the factors which may influence the results when using computational fluid dynamics (CFD) to model the flow field within a gas-lift bioreactor was performed. It was determined that one of the main factors which must be considered when modelling bioreactors with boundary layer flow separation is the choice of turbulence model. In the case presented here it was found that the transition SST turbulence model provided the best results with the k-w SST also performing well. Finally, a method of coupling the PN and CFD models was proposed and investigated. The photosynthesis-nutrient-hydrodynamic (PNH) model also incorporated a model for diffusion of light within the bioreactor to allow for investigations into the effects of light absorption and scattering within the bioreactor and how mixing affects the active biomass. Further investigation of this new PNH model determined that the coupling of the biokinetics and flow field provided some insight into the ability of a well-mixed bioreactor to counter low light penetration to an extent.
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Ji, Jing. "Poly(vinylidene fluoride) membranes." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/43532.
Full textAbstract:
Poly(vinylidene fluoride) (PVDF) membranes have been intensively investigated and commercialised with broad applications in water purification and wastewater treatment for decades due to its outstanding properties. Currently, PVDF membranes are mainly produced by the phase inversion technique, which is predominant in both laboratory research and industrial manufacturing. Various modification methods based on the phase inversion technique have also been developed to improve the membrane performances, but these improvements are incremental and there have been no important breakthroughs during the past decade. This thesis first explores the preparation of reinforced PVDF flat sheet membranes by blending nanoclay followed by the phase inversion process. Although the membranes showed improved water permeation flux and enhanced abrasion resistance, further improvements are limited by the phase inversion technique itself. Consequently, a new concept of membrane manufacturing procedure has been proposed by combining unidirectional crystallisation of green solvent and polymer diffusion. The new method uses crystallites of a solvent dimethyl sulfoxide with controlled sizes as pore templates to create enormous nanosized flow passages. It follows a completely different pore formation mechanism and therefore overcomes the drawbacks of the phase inversion technique. The resultant PVDF membranes have an asymmetric structure composed of a highly porous separation layer and gradually opened micro-channels. Due to the unique structure, the prepared membranes showed excellent permeation performances and mechanical properties overwhelming commercial PVDF membranes prepared by the phase inversion technique. The filtration performance of the PVDF membranes can be further improved by modification of the membrane material, for example, by blending polyethylene glycol in the dope solution. The obtained membrane with pore size of 36 nm showed extraordinary high flux of 1711 L/m2h and could withstand 35 bar in the test. Moreover, the new manufacturing process is of much fewer influencing factors compared to the phase inversion approach and thus highly reliable and repeatable. In principle, it is also applicable to other common polymeric membrane materials such as polyethersulfone and cellulose acetate.
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Puchongkawarin, Channarong. "Optimisation-based methodology for the design and operation of sustainable wastewater treatment facilities." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/44211.
Full textAbstract:
The treatment of municipal and industrial wastewaters in conventional wastewater treatment plants (WWTPs) requires a significant amount of energy in order to meet ever more stringent discharge regulations. However, the wastewater treatment industry is undergoing a paradigm shift from a focus on waste-stream treatment and contaminant removal to a proactive interest in energy and resource recovery facilities, driven by both economic and environmental incentives. The main objective of this thesis is the development of a decision-making tool in order to identify improvement opportunities in existing WWTPs and to develop new concepts of sustainable wastewater treatment/recovery facilities. The first part of the thesis presents the application of a model-based methodology based on systematic optimisation for improved understanding of the tight interplay between effluent quality, energy use, and fugitive emissions in existing WWTPs. Plant-wide models are developed and calibrated in an objective to predict the performance of two conventional activated sludge plants owned and operated by Sydney Water, Australia. In the first plant, a simulation-based approach is applied to quantify the effect of key operating variables on the effluent quality, energy use, and fugitive emissions. The results show potential for reduced consumption of energy (up to 10-20%) through operational changes only, without compromising effluent quality. It is also found that nitrate (and hence total nitrogen) discharge could be signficantly reduced from its current level with a small increase in energy consumption. These results are also compared to an upgraded plant with reverse osmosis in terms of energy consumption and greenhouse gas emissions. In the second plant, a systematic model-based optimisation approach is applied to investigate the effect of key discharge constraints on the net power consumption. The results show a potential for reduction of energy (20-25%), without compromising the current effluent quality. The nitrate discharge could be reduced from its current level to less than 15 mg/L with no increase in net power consumption and could be further reduced to < 5 mg/L subject to a 18% increase in net power consumption upon the addition of an external carbon source. This improved understanding of the relationship between nutrient removal and energy use for these two plants will feed into discussions with environmental regulators regarding nutrient discharge licensing. The second part of the thesis deals with the application of a systematic, model-based methodology for the development of wastewater treatment/resource recovery systems that are both economically and environmentally sustainable. With the array of available treatment and recovery options growing steadily, a superstructure modeling approach based on rigorous mathematical optimisation provides a natural approach for tackling these problems. The development of reliable, yet simple, performance and cost models is a key issue with this approach in order to allow for a reliable solution based on global optimisation. it is argued that commercial wastewater simulators can be used to derive such models. The superstructure modeling framework is also able to account for wastewater and sludge treatment in an integrated system and to incorporate LCA with multi-objective optimisation to identify the inherent trade-off between multiple economic and environmental objectives. This approach is illustrated with two case studies of resource recovery from industrial and municipal wastewaters. The results establish that the proposed methodology is computationally tractable, thereby supporting its application as a decision support system for selection of promising wastewater treatment/resource recovery systems whose development is worth pursuing. Our analysis also suggests that accounting for LCA considerations early on in the design process may lead to dramatic changes in the configuration of future wastewater treatment/recovery facilities.
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Chen, Wei. "Fate of emerging organic contaminants in Chinese wastewater treatment plants." Thesis, Lancaster University, 2016. http://eprints.lancs.ac.uk/83271/.
Full textAbstract:
There has been increasing concern about the widespread occurrence of emerging organic contaminants (EOCs) in the aquatic environment which could pose potential risks to humans and ecosystems. Wastewater treatment plants (WWTPs) are significant sources and major routes of EOCs entering the environment. There is therefore a need to study the fate of EOCs in WWTPs to improve the risk assessment for these EOCs. In this thesis, the passive sampling technique of diffusive gradients in thin-films (DGT) for in situ measurement of selected EOCs in water was developed in the laboratory and validated under the real world condition-a WWTP. This sampler was then employed to study the occurrence and removal efficiencies of EOCs in Chinese WWTPs, as China represents a significant and growing market for many of these chemicals. A novel DGT technique was developed for in situ measurement of EOCs in water, with hydrophilic-lipophilic-balanced (HLB) resin as the binding agent and agarose gel as the diffusion layer. The performance of DGT sampler (indicated by ratio of DGT-measured concentrations (CDGT) to the directly-measured concentration (Cb), the ratio of CDGT/Cb ranged from 0.9 to 1.1 indicating the excellent performance of DGT) in different pH, ionic strength and dissolved organic matter contents was tested with 11 chemicals and found to be relatively independent of pH (3.5-9.5), ionic strength (0.001-0.1 M) and dissolved organic matter (0-20 mg L-1). Time and diffusion layer thickness dependence experiments confirmed the principle of DGT for accumulated chemicals consistent with theoretical predictions. The performance comparison of three types of resins (HLB, XAD18 and Strata-XL-A) was undertaken. Resin properties and the interactions of functional groups between the resin and chemicals controlling the uptake of EOCs for DGT sampler were evaluated by comparing the uptake capacities and the kinetics of the test chemicals among three resins. The study in the laboratory, which is similar to above section for three types of DGT devices with HLB, XAD18 and Strata-XL-A resins as the binding gels, confirmed the potential application of DGT principle for in situ measurement of EOCs in water. This DGT sampler was then compared with active sampling approaches, auto-sampling and grab-sampling in a WWTP. This study showed that the DGT sampler can continuously uptake the majority of detected EOCs in wastewater for 7-18 days. The time-weighted average concentrations measured by DGT were found to be comparable with the results delivered from the auto-samplers, showing similar concentrations and patterns. The effect of diffusive boundary layer was estimated, and was found to be relatively limited and much less compared with other passive samplers, demonstrating the advantage of DGT sampler. The field validation confirmed applicability of DGT sampler for studying the fate of EOCs in the wastewater. Before application of the DGT sampler into a large scale of fate study in Chinese WWTP, a sensitive analytical method was developed for simultaneous determination of target EOCs in surface water and wastewater. This method was optimised from solid-phase extraction (SPE) procedures to liquid chromatography-mass spectrometer (LC-MS) analysis, and was demonstrated to provide reliable data for the samples with complex matrix and low enough detection limits for EOCs in the water. This analytical method could perform similarly or even better to some related studies for detection of the EOCs in wastewater. DGT devices with HLB resin gels were then applied to 10 WWTPs in China for studying the occurrence and removal of EOCs. All target EOCs could be found in the raw influent and majority of them (18 of 20) could still be detected in the final effluent. Removal efficiency of the EOCs varied, showing the performance of different treatment technology/processes on the EOCs removal in wastewater. The primary and secondary treatment units contributed to the most removal of the EOCs. This demonstrated that DGT sampler can be an effective and simple tool to study in fate of EOCs in wastewater. This research programme has shown that DGT sampler is an effective tool for studying the fate of wide range of emerging organic chemicals in the aquatic environment and assessing their risk/ toxicity of EOCs to the human and ecosystem.
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Manga, Musa. "The feasibility of co-composting as an upscale treatment method for faecal sludge in urban Africa." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/16997/.
Full textAbstract:
Despite the improvements made to deliver improved sanitation around the world, Faecal Sludge (FS) management is still a challenge affecting hundreds of millions of people. Composting is one of the well known and most preferred low-cost methods for treatment of FS in urban Africa. However, its effectiveness has not been thoroughly explored. With an aim of improving the FS composting process in terms of nutrient recovery and pathogen inactivation; this study investigated the optimum sand filtering media thickness (150 mm, 250 mm, 350 mm) for FS drying beds, as well as the effects of different bulking agent types (sawdust, coffee husks and brewery waste), turning frequency (3, 7 and 14 days) and organic solid waste types (market waste and chicken feathers) on the FS composting process. Field dewatering and composting trials were conducted in Kampala, Uganda. The investigation revealed that the media thickness had a significant effect on the removal and recovery efficiency of percolate contaminant loads, but not on the dewatering time. The dewatering time improved to 3.65 - 4.02 days resulting into 65 - 67% reduction in the land area requirement per capita (0.016 - 0.017 m2/capita) for the treatment of FS to about 37%TS. The 350 mm filtering media thickness was the most efficient, in terms of contaminant loads removal from FS. However, 150 mm media thickness had the greatest potential of optimising nutrient recovery (NPK) from FS, particularly were the resulting solids are to be composted. The results indicated that the solid loading rate of 441 kg/m2/year can be used as the design criterion for FS drying beds in urban Africa. The results showed that the bulking agent types, turning frequency and organic waste types had a significant effect on most of the key physico-chemical and biological composting parameters. Overall, sawdust was the most suitable bulking agent for co-composting with FS as it enhanced nutrient recovery. It exhibited the lowest N-losses of only 2.2% compared to coffee husk and brewery waste with 48.2% and 72.5%, respectively. The results indicated that composting with high turning frequency (3 days and 7 days) enhances pathogen inactivation efficiency, organic matter degradation and composting rate, and thus reduced the composting periods by about 33%. However, it was associated with higher N-loss of about 50.1 - 48.6% compared to 7.6% of low turning frequency (14 days). Overall, the 7 days turning frequency was the most suitable and economically feasible for use during the FS composting. On the whole, chicken feather waste was the most suitable organic waste type for co-composting with FS as it enhanced pathogen inactivation efficiency and nutrient recovery. The composting of FS with both chicken feather and market waste reduced the composting periods by 32% and enhanced pathogen inactivation rate as well as nutrient recovery through nitrogen conservation, by a factor of 3. The composting of FS with chicken feather reduced the pathogen inactivation periods by 42%. This could thus increase the capacity of FS treatment plants or reduce their required capital investment, operational costs by 42%. The study revealed that a composting period of 8 weeks with temperatures of around 50.7 - 58.7°C sustained in the piles for more than 31 days, using 7 days turning frequency, is sufficient to ensure complete inactivation of pathogens in FS. Pathogen inactivation in composting piles was not solely dependent on the temperature-time factor, but also other mechanisms such as microbial antagonistic mechanisms or antibiotic action induced by indigenous microbial, moisture content, change in pH, nutrient depletion, and toxic by-products such as NH4-N. The following indices were established for mature FS compost; NH4-N < 0.55 g/kg, C/N ratio < 12.7, NH4-N/NO3-N < 0.12, CO2-C respiration rate < 1.44 mg CO2-C-g TVS-1day, PGI > 100%, WSC < 12.3 g/kg, WSNH4-N < 0.03 g/kg and WSNH4-N/WNO3-N < 0.18. The results indicated that a composting period of 14 weeks is required to obtain both stable/ mature and pathogen free FS compost, thus co-composting can be a viable way of treating FS in urban Africa.
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Nguyen, Hoa Huu. "Modelling of food waste digestion using ADM1 integrated with Aspen Plus." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/375082/.
Full textAbstract:
The aim of this research was to produce an integrated modelling platform in which an anaerobic digester could be linked to the other unit operations which serve it, both in maintaining the physical-chemical conditions in the digester and in transforming the digestion products to useful fuel and nutrient sources. Within these system boundaries an accurate mass and energy balance could be determined and further optimised, particularly where the desired energy products are a mix of heat, power, and biomethane. The anaerobic digestion of food waste was choosen as the subject of the research because of its growing popularity and the availability of validation data. Like many other organic substrates, food waste is potentially a good source of renewable energy in the form of biogas through anaerobic digestion. A number of experimental studies have, however, reported difficulties in the digestion of this material which may limit the applicability of the process. These arise from the complexity of the biochemical processes and the interaction between the microbial groups that make up the anaerobic community. When using food waste there is a tendency to accumulate intermediate volatile fatty acid products, and in particular propionic acid, which eventually causes the pH to drop and the digester to fail. Two factors are important in understanding and explaining the changes in the biochemical process that leads to this condition. The first is due to the differential in sensitivity to free ammonia of the two biochemical pathways that lead to methane formation. The acetoclastic methanogenic route is inhibited at a lower concentration than the hydrogenotrophic route, and methane formation therefore occurs almost exclusively via acetate oxidation to CO2 and H2 at high free ammonia concentrations. The accumulation of propionic acid is thought to be because formate, a product of its degradation, cannot be converted to CO2 and H2 as the necessary trace elements to build a formate dehydrogenase enzyme complex are missing. The Anaerobic Digestion Model No. 1 (ADM1) was modified to reflect ammonia inhibition of acertoclastic methanogenesis and an acetate oxidation pathway was added. A further modification was included which allowed a 'metabolic switch' to operate in the model based on the availability of key trace elements. This operated through the H2 feedback inhibition route rather than creating a new set of equations to consider formate oxidation in its own right: the end result is, however, identical in modelling terms. With these two modifications ADM1 could simulate experimental observations from food waste digesters where the total ammoniacal nitrogen(TAN) concentration exceeded 4 gN l-1. Under these conditions acetate accumulation is first seen, followed by proprionate accumulation, but with the subsequent decrease in acetate until a critical pH is reached. The ADM1 model was implemented in MATLAB with these modifications incorporated. The second part of the research developed an energy model which linked ADM1 to the mechanical processes for biogas upgrading, Combined Heat and Power (CHP)production, and the digester mixing system. The energy model components were developed in the framework of the Aspen Plus modelling platform, with sub-units for processes not available in the standard Aspen Package being developed in Fortran, MS Excel or using the Aspen Simulation Workbook (ASW). This integration of the process components allows accurate sizing of the CHP and direct heating units required for an anaerobic digestion plant designed for fuel grade methane production. Based on the established model and its sub-modules, a number of case studies were developed. To this end the modified ADM1 was applied to mesophilic digestion of Sugar Beet Pulp to observe how the modified ADM1 responded to different substrate types. Secondly, to assess the capability of adding further mechanical processes the model was used to integrate and optimise single stage biogas upgrading. Finally, the digestion of food waste in the municipal solid waste stream of urban areas in Vietnam was considered.
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Roberts, Keiron. "Anaerobic digestion of marine microalgae." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/388117/.
Full textAbstract:
Anaerobic digestion is a simple and energetically efficient way in comparison to some other biofuel methods of producing renewable energy from a range of biomass types. Although digestion of micro-algal biomass was first suggested in the 1950s, only a few studies have been conducted for assessment of its performance. This work assessed the potential for energy recovery from microalgae via anaerobic digestion for both freshwater and marine species. This research screened seven laboratory-grown marine and freshwater microalgal species (Nannochloropsis. oculata, Thalassiosira . pseudonana, Dunaliella. salina, Rhododomas sp, Isochrysis. galbana, Chlorella. vulgaris and Scenedesmus sp) and two samples from large-scale cultivation systems for their suitability as a substrate for anaerobic digestion. Biochemical methane production and a theoretical maximum growth yield of each species were employed to offer a means of comparing methane productivity per unit of cultivation under standard conditions. The data generated were useful in determining suitable species to culture and digest under continuous operation. A review of the literature highlighted a gap in the knowledge for the continuous digestion of different marine micro-algal species, as well as the potential inhibitory effect of high salinities on the anaerobic digestion process to non-acclimatised systems run under continuous operation. Addition of total salt ≥ 10g L-1 caused reactor failure, supporting the findings of the literature review. It was possible, however, to gradually adapt the inoculum to marine concentrations of chloride salts (31.1 g L-1) with <7% difference in specific methane production of controls. Addition of sulphate showed competition between methanogens and sulphate-reducing bacteria with further minor losses in methane yield. There was up to 60% reduction in SMP for the highest sulphate loaded reactors, however, the population successfully adapted to sulphate concentrations above those typically found in seawater and showed gaseous H2S productivity in proportion to the applied sulphate load. This suggests that the effects of marine concentrations of chloride and sulphate salts can be overcome by a gradual acclimatisation. The selected algal species I. galbana and D. salina were continuously cultivated in a photobioreactor under low and high sulphate media and continuously digested using the salt adapted inoculum. The specific methane production for I. galbana and D. salina was 0.19 and 0.23 L CH4 g-1 VS, with a VS destruction of 32% and 50% respectively. Addition of a high SO4 grown D. salina as a feed resulted in a reduction of SMP to 0.19 L CH4 g-1 VS with an increase in H2S production. Loses in total solids and sulphur were observed under continuous study due to oxidation of H2S and struvite precipitation within the reactors, which was not observed under batch analysis. This highlights the importance in conducting continuous studies over batch, as these effects can be overlooked.
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Edward, Stephen Robert. "Anaerobic digestion of freshwater microalgae : effects of reactor type, operation and cultivation conditions." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3415.
Full textAbstract:
This thesis evaluates the technical potential of using microalgae as a substrate for anaerobic digestion. Investigating the control and operation of different reactors, under different operating conditions (OLR, SRT, HRT) to determine potential of microalgae as a feedstock and determine whether improvements in performance can be achieved. Thermophillic digestion offers higher methane yields compared to mesophilic digestion in simple reactor systems at 25 day SRT, being able to cope with higher organic loading rates. Low C:N ratio in microalgae has the potential to result in high levels of ammoniacal nitrogen within anaerobic systems with levels as high at 754 mgTAN/L observed at maximum loading rates. No apparent inhibition was observed in any reactor, with free ammoniacal nitrogen levels of 100 mg/L achieved without any drop in methane yield. While a UAnMBR system offered improved yields compared to CSTR systems, its performance was still relatively poor compared to theoretical maximum yields. The UAnMBR system did however cope with high hydraulic throughput (low HRT) without a significant drop in methane yield demonstrating that this system is potentially suitable for simultaneous harvesting and digestion. The microalgal biomass was inherently resistant to degradation, and over the duration of a lengthened growth cycle, can change its intracellular and cell membrane structures, changing its susceptibility to enzymatic attack and subsequent methane yield. Nutrient depletion in batch microalgae culture results in intracellular lipid and carbohydrate accumulation, which potentially could have resulted in a higher methane yield of 0.283 LCH4/gVSin (equivalent to 0.184 - 0.201 iii LCH4/gCODin) when compared to microalgae harvested during nutrient replete conditions. Allowing cultures to mature for longer periods in the stationary phase of growth under nutrient depleted conditions resulted in a significant reduction in methane yield to 0.174 LCH4/gVSin (0.124LCH4/gCODin). The selection of microalgal species appears to significantly affect the methane potential and degradation rates, with methane yield as high as 0.313 LCH4/gVSin (0.222 LCH4/gCODin) and as low as 0.130L CH4/gVSin (0.092 LCH4/gCODin) found in different pure cultures. The difference in yield was considered to stem from a wide variability in intracellular and cell wall structures. Poor correlation existed between gross biochemical content (protein, lipid, carbohydrate) and the methane yield, and confirms that variability in methane yield is not solely dependent on the biochemical composition (e.g. lipid content).
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Yulistyorini, Anie. "Phosphorus recovery from wastewater through enhanced micro-algal uptake." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15239/.
Full textAbstract:
Phosphorus (P) is an important constituent for living organisms as an energy carrier and a component of important biomolecules, which cannot be substituted with another element. Also, it is considered as the main element inducing eutrophication in freshwater bodies. In order to control eutrophication, wastewater treatment works (WWTW) remove P from their final effluent mostly through chemical precipitation and biological bacterial uptake. However, in order to achieve nutrient recovery from wastewaters, it has been suggested alternative biological processes based on biological algal uptake. Microalgae can be used to recover P from wastewaters as they can assimilate high amounts of P for their growth and store any excess as polyphosphate (i.e., luxury P uptake). This study is aimed at examining the potential use of microalgae cultivation for P recovery from wastewater and to identify the implications for its implementation at large WWTW. Chlamydomonas reinhardtii 11/32C was chosen as a model organism for this study. With regard to the role of the Nitrogen (N) source (ammonium v. nitrate), results show that there is little impact on P uptake when either ammonium or nitrate is used as the N source; however, by using a mix of ammonium and nitrate, P uptake increases as a result of stress conditions as ammonium is consumed faster than nitrate. Controlling environmental factors for microalgae growth showed that luxurious intracellular P uptake can range between 0.3 and 3.6% dry weight; optimum conditions for algae growth and P uptake where controlled by N concentration (200 mg N L-1, 50:50 NH4+:NO3-), phosphate concentration (100 mg P L-1 ), light intensity (250 μEm-2s-1) and photoperiod (16 hr light: 8 hr dark), resulting in a maximum algal biomass production of 148 mg VSS L-1d-1 and intracellular P uptake of 2.8 mg P L-1d-1. This study proved that C.reinhardtii 11/32C able to store the excess of P as polyphosphate granules located in cell’s vacuole. A continuous flow mixotrophic microalgae cultivation system was operated to investigate its performance as a novel biological nutrient control and recovery process. Under tested conditions, the mixotrophic system was able to remove both nitrogen and phosphorus at 97% and 50% respectively, with average P uptake of 2.03 mg P L-1 d-1 and algal biomass production of 248 mg VSS L-1 d-1. This system in operation generated on average 2.6 g L-1 of harvested algal biomass per day with a P content of 2.1% dry weight. These results show that a mixotrophic microalgae system has the potential to be implemented as a tertiary wastewater treatment process for biological nutrient removal and hence, a desktop case of study was conducted using data from a full-scale WWTW to assess the feasibility to implement this approach for nutrient recovery.
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Pacheco, Ruiz Santiago. "Submerged anaerobic membrane bioreactor for wastewater treatment : effect of mean cell residence time on membrane flux, mixed liquor characteristics and overall reactor performance." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/403002/.
Full textAbstract:
Mean cell residence time (MCRT) is a major operational parameter in all biological treatment systems because of its relationship to growth rate and thus to metabolic activity. Due to their mode of operation, submerged anaerobic membrane bioreactors (SAnMBR) offer a homogenous system in which MCRT can be simply controlled through volumetric wastage. Although a number of studies using SAnMBR have been reported, however, little information is available regarding the effect of MCRT on operational performance, mixed liquor characteristics and the influence of these on membrane performance. In this research an innovative SAnMBR using gravity-induced transmembrane pressure to maintain flux was developed and tested for first time. This configuration was then used to evaluate the impact of MCRT on membrane flux, mixed liquor characteristics and overall performance of SAnMBR treating low-to-intermediate strength wastewater. Long-term experimental periods of more than 240 days allowed steady-state conditions under different MCRTs, in which the mixed liquor suspended solids (MLSS) adjusted to the applied load, making possible to assess the influence of this growth and metabolism-dependent kinetic parameter. The SAnMBRs were monitored for membrane flux, overall process efficiency and mixed liquor characteristics when operating at 36 oC and 20 oC. The results of this work showed that at both operational temperatures, the MCRT has a significant effect on the mixed liquor characteristics, particularly on the filterability which was higher at short MCRTs. This resulted in improved membrane flux at relatively short MCRT, although no advantages were observed if the MCRT was further reduced. Higher specific methane production was observed at longer MCRT, most probably due to a higher fraction of carbon incorporated into biomass as a result of higher microbial growth rates. Overall, the results of this research showed that the MCRT has a considerable effect on the mixed liquor characteristics and thus on the membrane fouling and overall reactor performance. It is clear that there is a trade-off to be made between enhanced membrane performance, specific methane production and sludge yield when considering the most suitable operational MCRT. Further studies are required to identify the optimum MCRT for a wider range of wastewater and other operational parameters and to fully understand the causes of these effects.
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Booker, Victoria. "Investigating the occurrence and fate of anticancer drugs in sewage treatment works and the wider aquatic environment." Thesis, Lancaster University, 2015. http://eprints.lancs.ac.uk/82556/.
Full textAbstract:
The occurrence of pharmaceuticals in wastewater and the wider environment is of growing concern. This thesis focuses on anticancer drugs - a group of biologicallypotent and often recalcitrant set of chemicals whose fate and impact on the wider freshwater environment is poorly studied. The aims of this thesis were to prioritise a group of anticancer drugs for environmental monitoring programmes (from the many drugs in use), based on their consumption and fate during wastewater treatment; to undertake a national and regional survey of two commonly used anticancer drugs, cyclophosphamide (CP) and ifosfamide (IF) in wastewater and river water; to assess the performance of a river-based chemical fate model through comparisons with field observations; and to conduct a mass balance for CP in wastewater treatment plants to assess chemical fate during the different stages of wastewater treatment. Given the large number of anticancer drugs currently in use (>70) a decision support process was developed to ascertain a short list of drugs which are most likely to persist and be released with treated effluent to environmental waters. To do this, accurate consumption data were compiled from a hospital survey in NW England and combined with urinary excretion rates derived from clinical studies. Physical– chemical property data were then compiled along with likely chemical fate and persistence during and after wastewater treatment. A shortlist of 15 chemicals (from 65), including CP and IF, was prioritised based on their consumption, persistency and likelihood of occurrence in surface waters and supported by observational studies where possible. The ecological impact of these ‘prioritised’ chemicals however is uncertain as the measured concentrations in surface waters generally fall below standard toxicity thresholds, although there is evidence that exposure of aquatic organisms to some of these chemicals may induce low-dose genotoxic effects. This prioritised sub-list of anticancer drugs should prove useful for developing environmental screening programmes and targeted toxicity assays. To assess the occurrence of anticancer drugs in wasterwaters both CP and IF were measured in raw influent and final effluent waters from fourteen STPs located across England using a sensitive analytical method. CP was detected in both wastewater influent and effluent with mean (SD) concentration of 4.1 ng/L (4.8) and 6.6 ng/L (6.5), respectively, in agreement to measured ranges from a limited number of studies conducted in Europe and elsewhere. IF was only detected in four wastewater samples with the highest concentration being observed in wastewater effluent at 0.77 ng/L (cv = 24.3% (n=3)) and possibly reflecting the relatively lower consumption of this drug relative to CP. Additional monitoring was conducted in the rivers Calder, Darwen and Ribble (North West UK) with CP present at 5 of the 6 river locations with concentrations ranging from 0.41 to 3.71 ng/L. All these rivers receive treated wastewater effluent from sewage treatment works serving different population sizes, with CP measured in river water some ~20 miles downstream of the nearest STP, indicating the widespread dispersal and persistence of this chemical. CP and IF were measured systematically down the Rivers Aire and Calder in NE England and the results compared to a GIS-based water quality model (LF2000- WQX) used to predict CP and IF distributions in the two rivers, using regional consumption data and subsequent release quantities from STPs. CP was detected in 90% of river samples, apart from rural/uplands sites located at the source of the River Aire and Calder, respectively. CP presented the highest concentration, ranging from 0.17 to 4.53 ng/L (average 1.14 ng/L). IF was seldom detected in the sampled sites and concentrations ranged from < LOD to 1.82 ng/L (average 0.51 ng/L). Model results showed a fair agreement to the measured data for CP in the River Aire, discrepancies arise as the river progressed further downstream where the modelled data was lower than the measured data. A significant input of CP from Leeds STP at A7 (STP-1) saw the continuing rise in CP despite the increase in river flow. At the lower end of the Calder (pre-confluence with the River Aire) a spike in CP is detected far beyond the modelled value. A risk assessment was carried out to establish the potential adverse effects of anticancer drugs in the river catchment. All calculated risk quotients were below 1, showing no significant risk to aquatic organisms. However, long term toxicity studies for these chemicals are needed to define the environmental stress produced by their continuous exposure and induction. The fate and removal efficiency of cyclophosphamide (CP) and ifosfamide (IF) were investigated in two conventional sewage treatment plants (STP-S and STP-C) during different stages of waste water treatment. Overall average concentrations of CP were 1.17±1 ng/L in the two plants, which is lower than recent measurements conducted elsewhere. Grab-samples were coordinated with the hydraulic residence time of wastewater in each of the treatment stages in order to monitor changes in CP concentrations in the same parcel of water as it passed through the STP. Interestingly, concentrations of CP were observed to increase from raw influent to final tertiarytreated effluent and this is likely to be attributable to the degradation of a CPmetabolite and subsequent ‘liberation’ of the parent CP as the metabolite passes through the various sewage treatment processes. This observation, apparent in both studied STPs, has implications for chemical fate modelling of anti-cancer drugs, especially if STP influent loads are used to predict subsequent fluxes to receiving waters rather than final effluent values. Moreover, this increase in concentrations made a mass balance difficult to achieve, but highlighted that elimination/removal of CP in wastewater during primary to tertiary processing is very low (<20%). The calculated fluxes of CP with final effluent discharge were 3.16- 6.48 g/year for STP-S and 4.56 -51.57 g/year for STP-C and highlight that STPs are a continuing source of highly water-soluble, recalcitrant anticancer drugs to the environment.
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Khajah, Mishari. "Engineering aspects, pathways and mechanisms of nitrogen removal in engineered wetland systems." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/100956/.
Full textAbstract:
While constructed wetlands (CWs) have been applied successfully to achieve contaminant removal from several types of wastewater, their efficiency and capacity is still low with respect to nutrients (nitrogen, N and phosphorus, P) removal. Through typical configurations, the removal efficiency for total nitrogen (TN) varied between 40 and 50% and total phosphorus (TP) between 40 and 60% depending on CWs type and inflow loading. This limits their implementation in delivering advanced wastewater treatment. Subsequently, the main aim of this study was to develop innovative CW processes to significantly enhance the nitrogen removal efficiency by investigating a new approach to the configuration of CWs and exploring substitutional operational strategies. If this is accomplished, it could make CWs a main wastewater treatment unit instead of conventional wastewater treatment systems. To accomplish this aim, two systems (multistage and single stage CW) were developed and comprehensively investigated and studied by applying a tidal flow operational strategy with gravel used as the main media for both systems. Tidal flow enhances and promotes the oxygen transfer to the CW system by batch pulse feeding and producing alternant wet/dry conditions of the CW media with wastewater. The multistage configuration is connected by four identical units in series and is divided into two phases depending on the seasonal temperature. The results of the multistage configuration showed average values for removal of 97.3%, 98.1%, 77.3% and 16.6% for chemical oxygen demand (COD), ammonium (NH₄⁺-N), TN and TP respectively for phase 1, and 87.5%, 78.5%, 60.3% and 10.2% for COD, NH₄⁺-N, TN and TP respectively for phase 2. However, TN removal was still not desirable with a mean removal efficiency in both phases 1 and 2, whereas the satisfactory removal for TN is >80%. This is due to the seasonal temperature and because all the stages were under aerobic conditions to a certain extent, which is unfavourable for denitrifying bacteria. Subsequently, to obtain a satisfactory efficiency of TN removal performance, the original multistage configuration system has been modified. To obtain a high and efficient TN removal performance for the multistage system, further investigations and developments have been made regarding system modification and alternative operational options. These have resulted in the development of improved nitrogen ABSTRACT iii removal processes by applying a step-feeding strategy to the system with different step-feeding schemes. As a result, 81.1% of TN removal was achieved. In addition, TP removal was poor because the system was not designed to removal phosphorus. The results of the single stage CW showed average values for removal of 86.7-99.3% and 64.1-74.8% for NH₄⁺-N and TN respectively, depending on the recirculation number (Rn) and inorganic carbon concentrations (IC); a single stage CW was used to follow the new route of nitrogen removal, called the Complete Autotrophic Nitrogen removal Over Nitrite (CANON) process. Microbial community analysis revealed that the dominant phyla for the multistage system were Proteobacteria, Planctomycetes, Firmicutes, and Bacteroidetes, whereas the dominant phyla for the single stage were Proteobacteria, Planctomycetes, Acidobacteria, and Chloroflexi. All these phyla were responsible for nitrogen and organic matter removal in both systems. The difference in microbial community and structure between both systems might attributed to the differences in the operational conditions. Overall, the results of this research study enhance the treatment capacity, which enables CWs to have the potential to work as the fundamental technology in advanced wastewater treatment and to increase our understanding of nitrogen removal in CW systems.
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Dias, Edgard Henrique Oliveira. "Bacteriophages as surrogates of viral pathogens in wastewater treatment processes." Thesis, University of Brighton, 2016. https://research.brighton.ac.uk/en/studentTheses/9606c027-b1ad-4204-91e2-b906a842e888.
Full textAbstract:
Although wastewater reuse presents numerous benefits, wastewater-borne pathogens, especially human enteric viruses, may pose risks to human health. Wastewater treatment processes have been shown to remove bacterial pathogens more effectively than they do viral pathogens, and in aquatic environments, levels of traditional faecal indicator bacteria (FIB) do not appear to correlate consistently with levels of human viral pathogens. There is, therefore, a need for novel viral indicators of faecal pollution and novel surrogates of viral pathogens. Potential candidates for this role include enteric bacteriophages (phages), viruses capable of infecting enteric bacteria.
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Emanuele, Sozzi. "Low-cost physico-chemical disinfection of human excreta in emergency settings." Thesis, University of Brighton, 2016. https://research.brighton.ac.uk/en/studentTheses/1d15b231-f0bc-4251-bf5c-7d7912073d84.
Full textAbstract:
The operation of a health-care facility, such as a cholera or Ebola treatment centre in an emergency setting, results in the production of pathogen-laden wastewaters that may potentially lead to onward transmission of the disease. The research presented here outlines the results of field and laboratory studies devised to inform the design and operation of a novel full-scale treatment protocol to disinfect pathogen-laden hospital wastewaters in situ, thereby eliminating the need for potentially hazardous road haulage and disposal of human excreta or wastewater to poorly-managed waste facilities. The approach investigated has the potential to provide an effective barrier to disease transmission by means of a novel but simple sanitary intervention. During Phase I of this research, a fieldwork study in Haiti focused on the design and operation, at short notice and within a disaster setting, of a new treatment technology that aimed to obviate the transport of untreated human excreta from emergency cholera treatment centres (CTC) to poorly-managed waste facilities. The results of this fieldwork period were validated and further optimised during Phase II: a detailed laboratory-based study in the UK that assessed the performance of the novel treatment technology in order to improve its efficacy. The performance of two physico-chemical protocols was monitored, first in the field (Port-au-Prince, Haiti), by means of both bench-scale and full-scale batch treatment of real highly-contaminated faecal waste from a cholera treatment centre (Phase I), and subsequently during more detailed laboratory studies (Phase II) using a ‘faecal-waste matrix’ that was created by mixing various municipal wastewaters and sludges in a proportion that aimed to mimic the composition of wastewaters produced at health-care facilities in emergency settings. The two investigated protocols achieved coagulation/flocculation and disinfection by exposure to high– or low–pH environments, using thermotolerant coliforms, intestinal enterococci, and somatic coliphages as indices of disinfection efficacy, and several physico-chemical parameters as indicators of treatment performance. In the high–pH treatment protocol, the addition of hydrated lime resulted in wastewater disinfection and coagulation/flocculation of suspended solids. In the low-pH treatment, disinfection (and partial colloidal destabilization followed by sedimentation) was achieved by the addition of hydrochloric acid, followed by pH neutralisation. A potential further step in this 4 second protocol was the coagulation/flocculation of suspended solids using aluminium sulphate. During Phase II, removal rates achieved for the high pH treatment protocol, in terms of physico-chemical parameters, were: COD > 80%; suspended solids > 85%; turbidity > 85%. Removal rates in terms of microbiological parameters were: thermotolerant coliforms > 5 Log10, intestinal enterococci >2 Log10 and somatic coliphage > 2 Log10. Removal rates achieved for the low-pH treatment protocol in terms of physico-chemical and microbiological parameters were: COD > 80%; thermotolerant coliforms between 0.2 and 1.2 Log10, with a mean removal of 0.75 Log10 and > 3 Log10 removal for intestinal enterococci. The removal of somatic coliphage was in excess of 4 Log10. The quantity and density of the sedimented sludge and several other physicochemical parameters (such as total nitrogen, total phosphorous, ammonia and ammonium, etc.) for the analysis of the supernatant were also monitored. This study represented the first known successful attempt to disinfect wastewater in a disease outbreak setting without resorting to the alternative, untested, approach of ‘super-chlorination’ which, it has been suggested, may not consistently achieve adequate disinfection. In addition, a basic costs analysis demonstrated significant savings in the use of reagent compared with super-chlorination. The approach to sanitation for cholera treatment centres and other disease outbreak settings presented here offers a timely response to a UN call for in situ disinfection of wastewaters generated in such emergencies. Further applications of the method to other emergency settings have been actively explored in discussion with the World Health Organization (WHO) in response to the ongoing Ebola outbreak in West Africa, and with the UK-based non-governmental organization (NGO) Oxfam.
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Yassin, L. "Appropriate scales and technologies for energy recovery by thermal processing of waste in the urban environment." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1446161/.
Full textAbstract:
In the developed world, 75% of the population live in urban areas, a figure projected to rise to nearly 83% by 2030, while in the developing world, the rate of urbanisation is even faster. One of the most important environmental problems associated with urbanisation is the amount of waste that is generated at a rate that outstrips the ability of the natural environment to assimilate it and authorities to manage it. Therefore, if we are to deliver a more sustainable economy, we must do more with less by making better use of resources. The recovery of energy from waste or EfW is an important component of an integrated waste management strategy, as it reduces our reliance on landfill. It is also a low carbon, low cost fuel, which by displacing fossil fuels can help the UK Government in meeting its energy policy and emission targets. Furthermore, EfW can contribute to energy security through diversification of supply it is projected that EfW may supply up 17% of the total UK electricity consumption by 2020. The main objectives of this work are to investigate the appropriate scales and technologies for the production of energy from waste in the urban environment. The suitability and effectiveness of fluidized bed combustion and gasification processes have been studied, together with gas clean-up systems. The most appropriate scales for each of these approaches in relation to system efficiencies and costs were evaluated, so that a sound judgement can be made as to which processes should be used in the urban context. Within this framework, a comprehensive assessment of fluidized bed reactor types and operational process conditions has been presented. Current and future status of these technologies was discussed, as well as the non-technical barriers hampering their development. The assessment concluded with a review of the different emissions and residues generated from the thermal treatment processes, their management, practices and costs. Mass and energy balances of traditional moving-grate combustion plants and key issues regarding the treatment of the output gas stream have been investigated during a five- month placement programme at Germana & Partners Consulting Engineers in Rome (Italy). The aim of the study was to gain an in-depth understanding of design methodologies and engineering principles applied in the detailed design of real industrial energy recovery plants. The study led to the development of a consistent approach for the technical and economic evaluation of more advanced technologies, namely fluidized bed combustion and gasification systems. Two different scale scenarios of 50,000 tpa and 100,000 tpa plant capacities were considered for the generation of electric power using a steam turbine for the combustion process and gas engine & combined cycle gas turbine (CCGT) for the gasification process. Mass and energy balances of the processes were performed and the cost effectiveness of the different waste treatment options was assessed using a discounted cash flow (DCF) analysis, which includes current market-based mechanisms, such as eligibility for Renewables Obligation Certificates (ROCs). A sensitivity analysis was carried out to evaluate the effects of changing system variables on the economic performances of the different waste treatment options. Seventeen system variables have been chosen and the effects of a 10% change in these variables on the levelised costs and gate fees were examined. These variables include waste calorific value, gasifier efficiency, prime mover electrical generation efficiency, as well as electricity and ROC prices and biodegradable fraction of the waste. As part of this study, the techno-economic performances of traditional moving-grate combustions systems was reported and compared against the different fluidized bed systems co-located with Mechanical Biological Treatment (MBT) facilities. The work was subsequently extended to analyse the technical and cost effectiveness of the simultaneous generation of heat and power from EfW fluidized bed combustion and gasification systems, using the same scale scenarios of 50,000 tpa and 100,000 tpa. The study focused on the additional capital and operating costs involved in incorporating combined heat and power (CHP) into EfW facilities. The projected revenues from heat sales and eligibility for ROCs were also evaluated for a range of market penetration levels. Furthermore, the environmental benefits associated with EfW with CHP facilities were assessed and the CO2 savings achieved from displacing fossil fuels in the separate generation of heat and power were also determined.
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Zhu, Xia. "Effect of microbubble on the performance of the partial nitrification and Anammox process." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/3914/.
Full textAbstract:
Nitrogen pollution is an increasingly important global concern because it has multiple impacts on terrestrial, aquatic and atmospheric environments. Nitrogen is usually present in wastewater as ammonium. Ammonium can be removed from wastewater by a variety of physicochemical and biological processes, but biological processes are preferred because they are usually more efficient and environmentally friendly. Conventional biological nitrogen removal is carried out by autotrophic nitrification and heterotrophic denitrification via nitrate, which use biodegradable organic matter as electron donor. However there are some kinds of wastewater with low concentrations of biodegradable organic matter such as landfill leachate and anaerobic digester supernatant. In these cases an external organic carbon source is necessary in order to obtain a complete denitrification, which implies higher economic cost. Partial nitrification- Anammox process as a promising and novel biological technology of removing nitrogen from high-strength ammonium wastewater with a low C/N ratio has attracted increasing attention due to its higher efficiency and cost-effectiveness compared with the conventional nitrification-denitrification nitrogen removal process. However, many challenges were faced during the development of stable and high-efficiency partial nitrification-Anammox performance, such as NOB activity, the effort to save energy, strict conditions and influent with favourable composition for Anammox. In order to improve the efficiency of Partial nitrification- Anammox process as much as possible whereas using the least energy, the microbubble generation system was firstly applied into the partial nitrification-Anammox process. The steady microbubble cloud produced by fluidic oscillator was verified size ranging from 60 μm to 600 μm which provides higher mass transfer rates and gas hold-up in gas-liquid phase bioreactor due to the fact that the microbubble was characterized by higher surface area to volume ratio and slower rising velocity. The simulation of the inner motion of the airlift loop reactor with COMSOL offered a visual difference between microbubble aeration and fine bubble aeration. In the partial nitrification process dissolved oxygen is a key factor for the growth of ammonia oxidizing bacteria (AOB). Two contrasting experiments in sequencing batch airlift loop reactors (SBAB) with and without fluidic oscillator were conducted over 200 days to investigate the effect of microbubble aeration system on the long term partial nitrification process. The results showed the microbubble aeration system can significantly enhance the activity of AOB to speed up the biological treatment with fewer oxygen requirements and effectively prevent the production of nitrate. The performance of the partial nitrification in an airlift loop bioreactor with fluidic oscillator was greatly improved in terms of treatment capacity and stability compared to the one without fluidic oscillator. Thereafter different operational parameters such as temperature and pH were examined to optimize the operational strategies for the partial nitrification process. The microbial communities that catalyse partial nitrification were analysed by molecular biotechnology. The morphology of bacteria at different growth stages was observed by SEM and TEM. Real-time PCR was used to quantify populations of ammonia-oxidizing bacteria and nitrite oxidizing bacteria. For the Anammox process, a strict anaerobic condition is required to operate successfully. As we all know, the stack gas is usually consists of depleted oxygen but mostly nitrogen (typically more than two-thirds) derived from the combustion, carbon dioxide (CO2), and water vapour, among which CO2 is considered as a greenhouse gas contributing to global warming. Bubbling the synthetic power station stack gas into the Anammox reactor by means of the microbubble generation system not only obtain this circumstance but also provide the heat required by good activity of anammox bacteria. In addition to maintaining desirable conditions, the dissolved CO2 can provide a carbon source for the growth of anammox bacteria and adjust the value of pH in the reactor which is able to save substantial operational cost caused by pH control. Two contrasting experiments in round sequencing batch gas lift loop bioreactors (SBGB) with and without fluidic oscillator were carried out nearly 100 days. The performance of Anammox process in the SBGB with fluidic oscillator was noticeably improved comparing to the one without fluidic oscillator. The size distribution of granular Anammox sludge was analysed by ImageJ to investigate the effect of microbubble on the granulation. The batch assays were conducted to measure the maximum specific Anammox activity in different gas lift loop bioreactors. The morphology of Anammox bacteria at different growth stages was observed by SEM and TEM. Real-time PCR was used to quantify populations of Anammox bacteria in different stage and different bioreactors. The kinetic model for laboratory-scale partial nitrification and Anammox (anaerobic ammonium oxidation) process with sequencing batch gas lift loop bioreactors (SBGB) with and without fluidic oscillator were investigated. According to Monod model and Stover-Kincannon model the kinetic parameters of the model including maximum specific rates and half-maximum rate concentrations for partial nitrification and Anammox were estimated respectively from the results obtained from a laboratory-scale SBGB fed with synthetic wastewater.
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Shen, Licheng. "Investigation of the removal and recovery of metal cations and anions from dilute aqueous solutions using polymer-surfactant aggregates." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:33afa911-3ffb-484e-8db5-b6843928f175.
Full textAbstract:
Dilute metallic ion treatment (< 10 mg/L) remains a challenge in water purification and resource recovery. A novel and inexpensive treatment process that employs polymer-surfactant aggregates (PSAs) has been developed and applied to remove and recover dilute metallic ions, such as Cr3+, Rh3+, Cd2+, Fe(CN)6 3- and CrO42-, from industrial process and effluent. At the heart of this process is a material that comprises a colloidal structure of polymers and surfactants, named a polymer-surfactant aggregate (PSA), that trap metallic ions. The ion loaded PSAs then coalesce and settle out. The flocs are then treated separately by acid-base wash to recover the ions in a concentrated salt and regenerate the polymer and surfactant. The regenerated polymer and surfactant can then be recycled without a deterioration of removal ability in the next cycle. This process is simple, uses low energy, and generates little material loss or discharge. The thesis is divided into three main parts: fundamentals, cation treatment and anion treatment. First, the mechanism of formation of PSAs and their interactions with metallic ions are investigated using surface tension and electrical conductivity measurements. Both measurements reveal that the PSA is formed by surfactant monomers binding to the oppositely charged polymer chains and forming micelle-like aggregates via hydrophobic and electrostatic forces. These aggregates, like micelles, can bind to the oppositely charged metallic ions, but the surfactant concentration required is a few orders of magnitude lower than that required for micelle formation. The resulting nano-size PSA has a large surface area to volume ratio, and can effectively treat dilute aqueous streams. Each PSA consists of positive and negative charges. Within a near charge neutralisation range, they can quickly self-flocculate to simultaneously remove metallic ions and settle the flocs out of aqueous solutions. Correlating the removal efficiency of ions with surface tension and electrical conductivity measurements, the results suggest that the PSA is indeed responsible for removing the ions from the streams. Based on the fundamentals, a PSA process consisting of three stages (removal, recovery and recycle) is developed to treat metal cations in dilute streams. At the removal stage, polymer and surfactant (i.e. removal agent) are used to form PSAs and trap 99% of 0.1 mM metal ions into flocs. At the recovery stage, a small amount of acid solution is added to leach out 95% of the trapped metal ions into a concentrated salt, and then using a base solution to completely dissolve and regenerate the removal agent. After that, the removal agent are recycled in the next cycle without the need for any make-up, and little deterioration of removal ability is found. The same three-stage process is also applied to recover dilute metallic anions. As the targeted ions are negatively charged, the charge of polymer and surfactant used and the order of acid-base wash are reversed as compared with the cation treatment process. The PSA process is robust under different conditions, e.g. pH, temperature, salinity and organic contaminants. Such a sustainable process thus has potential applications for the efficient removal and recovery of dilute metallic ions during process effluent water treatment.
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Mwabonje, Onesmus N. "Phosphorus removal and recovery in water and wastewater." Thesis, University of Surrey, 2007. http://epubs.surrey.ac.uk/844201/.
Full textAbstract:
Phosphorus occurs in natural water and wastewater mainly as orthophosphates and polyphosphates. The major sources of phosphorus arising in municipal wastewater originate from both domestic and industrial waste flows. Approximately 50 to 70% of the phosphorus in domestic wastewater comes from human wastes and the remaining 30 to 50% comes from synthetic detergents containing phosphate components that are utilised for washing clothes. The fertiliser industry and commercial laundry systems comprise the bulk of industrial sources of phosphorus. The presence of excess phosphorus in the effluent discharged to natural waters has long been viewed as the cause of algae blooms and eutrophication. The average molar ratio of nitrogen, phosphorus and carbon in algae protoplasm is approximately 15:1:105, and therefore represents an optimum nutrient requirement ratio. The constituent that is present in the lowest concentration, taking into account this ratio requirement, will effectively limit algal growth. It can be deduced, therefore, that a minimal amount of phosphorus can still support substantial algae growth and its removal is more effective than nitrogen removal for preventing eutrophication in surface water. To this end, feasible methods for the removal and recovery of phosphorus from wastewater need to be studied. This study aimed to investigate the feasibility of using liquid-liquid extraction and enhanced coagulation methods to remove and recover phosphates from wastewater and water resources. The results revealed that to achieve the maximum phosphates removal by a liquid-liquid extraction method, the best extractant was a mixture of kerosene and benzyldimethylamine at a volume ratio of 2:1. The optimum volume ratio of the extractant and wastewater sample is 1:1, while the optimum extraction period was 6 hours with a shaking speed of 250 rpm. A phosphate extraction efficiency of greater than 80% was achieved across the three categories of water samples tested; a model water, lake water in the UNIS campus and real wastewater. A high stripping efficiency of greater than 90% was achieved from stripping the extractant used in treating each of the wastewater samples, using 6M sulphuric acid at a volume ratio of 1:1 with an agitation speed of 250 rpm. It was possible to re-use the resulting extractant from the stripping process nine times, when the overall phosphate removal efficiency was maintained by mixing the recycled to fresh extractant (kerosene and benzyldimethylamine at a volume ratio of 2:1) at volume ratios of 4:1 and 2:1 for the lake water and wastewater samples respectively. Aluminium sulphate, aluminium chloride and anhydrous iron chloride were used as chemical coagulants in the enhanced coagulation study. The doses applied for the two aluminium salts used were 4, 8, 12, 16 and 20 mg/L as while that of anhydrous iron chloride was 8, 16, 24, 32, and 40 mg/L as Fe3+. Turbidity removal efficiency of >80% was achieved when aluminium salts were used. The iron salt produced an efficiency of >80% for the sample pH 6 and 8. In addition, the removal efficiency increased with increase in the coagulant dose for all the coagulant salts used. The phosphates removal efficiency increased with increase in the coagulant dose and showed dependency on the pH of the wastewater samples. The major drawback of coagulation/precipitation is the excess sludge production in the process. This research revealed that a liquid-liquid extraction method is superior in respect of phosphate removal and recovery and has potential for use as an alternative method for industrial applications.
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Richards, Samia. "On-site wastewater treatment systems as sources of phosphorus and other pollutants in rural catchments : characteristics and tracing approaches." Thesis, Bangor University, 2017. https://research.bangor.ac.uk/portal/en/theses/onsite-wastewater-treatment-systems-as-sources-of-phosphorus-and-other-pollutants-in-rural-catchments-characteristics-and-tracing-approaches(cf2d6620-06b2-4737-8626-c6b736717585).html.
Full textAbstract:
This thesis investigated the influence of septic tanks (ST) on stream water quality. Characterisation of septic tank effluent (STE) revealed that STE were enriched in phosphorus (P), nitrogen (N), organic matter (OM) and metals relative to stream waters and large proportions of these parameters were present in the soluble reactive forms. Human factors such as tank design, number of users, dishwasher use and infrequent desludging significantly (P < 0.05) influenced effluent quality. ST that received roof runoff had reduced effluent retention time, while infrequent desludging was linked to increased OM, bacteria and P concentration in the effluent. Tanks that served larger numbers of people had elevated microbial abundance, P and N concentrations. Effluent composition was not consistent throughout the year, but exhibited similarity in warmer drier months that was different from effluent in colder wetter months for biological oxygen demand and heavy metals. Effluent attenuation in a test soil revealed that 14%-35% of P was attenuated by sorption processes, while saccharin was strongly attenuated by soil microbial degradation. The complex composition of STE reduced the ability of the test soil to adsorb P, as other substances in the effluent were competing for soil binding sites. Calculated P annual loadings from STE were 0.797 and 0.956 kgP/person/year for water usage of 150 and 180 l/person/day, respectively, while, effluents P load from detergents was 0.154 kg P/person/year. Newly developed tracing studies showed that ratios of chloride to other effluent indicators (e.g. EC, NH4-N, TSS, turbidity, total coliforms, sucralose, saccharin and Zn) and the detection of effluent tryptophan-like peak by fluorescence spectroscopy may be useful in tracking effluent discharge to streams with low levels of dilution. However, effluent caffeine and saccharin were more effective tracers in streams with low and high levels of dilutions. A single individual tracer alone was not sufficient to evaluate STE contamination sources, but combined chemical and physical tracing approaches show promise as tools to identify STE inputs that continue to pose risks to watercourses and where mitigation measures could be effectively targeted.
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Sim, Miaw Ching. "Two-stage MBR to reduce sludge production and total aeration volume." Thesis, University of Bath, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425863.
Full text
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Stephenson, Dianne. "Bioaugmentation for the improvement of nitrification in wastewater treatment." Thesis, Cranfield University, 1993. http://dspace.lib.cranfield.ac.uk/handle/1826/11195.
Full textAbstract:
The literature relating to nitrification in wastewater treatment and bioaugmentation
as a method to enhance wastewater treatment processes is reviewed.
The use of a commercially available bioaugmentation product (based on a
Nitrosomonas culture), which claimed to enhance nitrification in biological
wastewater treatment was investigated.The product was tested in full scale trials,
in shake flask experiments and its efficacy modelled using a simple activated
sludge simulation.
At full scale trickling filter plants a bioaugmentation product designed to enhance
BOO removal was also tested. This product increased BOO removal by up to 7%
in the recovery period following low temperature. The Nitrosomonas culture
improved percentage ammonia removal by nearly 10% in trickling filters even at
low temperatures of 6.5°C. A maximum improvement of 20% occurred at one
trickling filter site at higher temperatures.
At activated sludge sites the Njtrosomonas culture improved the nitrifying ability of
the activated sludge, as assessed by the laboratory standard method, and at one
site noticeably improved percentage ammonia removal during periods of high
dosing. At one site the maximum improvement was an increase of 22% in
percentage ammonia removal during high dosing. However the operational
parameters, loads, hydraulic retention time, mixed liquor suspended solids,
sludge age and temperature had a great effect on nitrification. If better process
control was applied at one of the works the plant would have had little trouble
nitrifying i.e. lower loads, higher HRT, MLSS and sludge age during low
temperatures. Sludge wastage regimes contributed greatly to the failure to nitrify.
It was found that the activity of the Nitrosomonas culture increased with
temperature and acclimatisation and decreased on inoculation into activated
sludge. The product facilitated nitrification when inoculated into non-nitrifying
activated sludge. Ammonia removal increased with size of inoculum.
The simple dynamic model described showed the development of a
Njtrosomonas population from inoculation with the Nitrosomonas culture. The
model showed that the effectiveness of a bioaugmentation product in activated
sludge would depend on the amount of nitrifiers returned to the aeration basin
more than other operational factors. The model predicted full nitrification at one of
the full scale sites within three days.
Bioaugmentation did enhance nitrification at full scale works. However, dosage
rates required for improvement meant that conventional methods such as better
process control or retrofitting would be economically more feasible.
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Fitria, D. "The impact of selected water and wastewater treatment process variables on sludge dewaterability." Thesis, University of Salford, 2014. http://usir.salford.ac.uk/31957/.
Full textAbstract:
The most significant operational cost in a treatment plant is related to the dewatering and disposal of sludge. Coagulation is the most common process in water and wastewater treatment plants and produces sludge as a by-product. The influence of different important coagulation factors has been investigated in this study to assess corresponding impacts on sludge dewaterability. The CST (Capillary Suction Time) apparatus was used as the main tool to measure sludge dewaterability, followed by the turbidimeter, the particle size analyzer, and the SRF (Specific Resistance to Filtration) as a comparison and also for verification. The CST results indicate that the magnetic stirrer produces the lowest CST values, while the other four shapes of mixers produced similar but higher trends. Rapid mixing velocity and rapid mixing time have varying degrees of influence on the CST value and hence on sludge dewaterability. Rapid mixing velocity seems to have a more significant impact on the CST value than rapid mixing time. The coagulants aluminium sulphate and ferric chloride have similar effects on CST values. The performance of aluminium sulphate and Moringa oleifera are affected by temperature, but the performance of coagulant ferric chloride was hardly impacted. Different synthetic water samples do not significantly affect the CST value. The turbidity result correlates well with the CST value. Observations using the particle size analyzer indicate that, in general, the floc size has a direct correlation with the CST value. The larger the floc size, the lower the CST value. Floc size distribution results show that synthetic raw water has a narrow particle size distribution; synthetic domestic wastewater produced a wider distribution than synthetic raw water. The comparison between the CST and SRF results indicates that the CST and SRF are well correlated if different methods (rapid mixing velocity and rapid mixing time) are used, but uncorrelated if different materials (mixers, coagulants, temperature and water samples) are used. Based on the results of this investigation, the working of the magnetic stirrer should be investigated further in order to implement this mixer in the treatment process. The magnetic stirrer does not only produce the lowest CST value but is also the only mixer that produces different CST values significantly. This is because it produces the optimum G value for sludge formation. The implementation of rapid mixing velocity is more important than rapid mixing time in the operation of a treatment plant. Due to its correlation with temperature, ferric chloride is the most appropriate coagulant among the three types of coagulants used in the treatment plant to reduce sludge dewaterability. Based on the results using different water samples, all of these factors can be used for both inorganic and organic water and wastewater to produce lower sludge dewaterability.
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Harris, Peter Richard. "Particle capture from liquid streams by filter papers." Thesis, University of Exeter, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393537.
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Collins, O. J. "Investigation into the fate of nutrients and crop growth following application of sewage sludge to land." Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/11406.
Full textAbstract:
Investigations into nitrate leaching from sludge and sludge injection into
grassland have been undertaken for many years, however phosphate leaching from
soils and shallow
injection of sludge into grassland are relatively new ideas.
This
lysimeter study sets out to investigate the influence of the type of slurry
and
application rate on the amount of phosphorus and nitrogen lost by leaching. The
field trial assesses the influence of
application methods on grass yield, sward damage
and
ritrogen loss by leaching through analysing the effects on a grass crop using two
different methods of
injection and comparing them with surface application and
granular fertilizer.
Losses of P from
sandy loam soils were found to be minimal therefore
contamination of
groundwater is thought to be unlikely. Similar leacling patterns were
observed from both the cake and
liquid sludges at all four rates_ applied, however the
liquid sludge released more phosphate than the cake sludge, resulting in higher
concentrations recorded.
The
lysimeter study also found leaching losses of ritrate from both sludge types
to be well above the EC maximum
permissible level of 11.3 mg nitrate-N l`l at all four
rates. Residual N from the
previously cropped soil masked the nitrate concentrations
during the initial stages of the study. Losses of N from the cake sludge was lower than
from the
liquid treated plots due to slow release. It was also found that environmental
factors such as
high temperatures and rainfall influence nitrate leaching.
The field trial
analysed various disposal methods in terms of nitrate leached,
crop yield and sward damage. N losses from shallow injection were reduced compared
to the
deep injection plots, as the sludge was placed in closer proximity to the crop
roots.
Olibhe Collins, Silsoe College, 1996.
In overall terms the shallow
injection system yielded the greatest quantity
compared to surface applied or the inorganic fertilizer. Damage caused by the tines
during shallow injection was not evident compared to the deeper injection system
where sward
damage and dieback was considerable.
The results from the field trial indicate that the shallow
injection of sewage
sludge has proved to the most environmentally friendly method for the disposal of
sludge to farm land.
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Intrachandra, Narisara. "The hydrodynamics of the anaerobic baffled reactor with dilute wastewaters." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393631.
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Samanya, Janat. "Increase of energy recovery from sewage sludge." Thesis, Aston University, 2013. http://publications.aston.ac.uk/20734/.
Full textAbstract:
The use of the pyrolysis process to obtain valuable products from biomass is amongst the technologies being investigated as a source for renewable energy. The pyrolysis process yields products such as biochar, bio-oil and non condensable gases. The main objective of this project is to increase energy recovery from sewage sludge by utilising the intermediate pyrolysis process. The intermediate pyrolysis has a residence time ranging from 5 to 10 minutes. The main product yields from sewage sludge pyrolysis are 50 wt% biochar, 40 wt% bio-oil and 10 wt% non condensable gases. The project was carried out on a pilot plant scale reactor with a load capacity of 20 kg/h. This enabled a high yield of biochar and bio-oil. The characterisation of the products indicated that the organic phase of the bio-oil had good fuel properties such as having high energy content of 39 MJ/kg, low acid number of 21.5, high flash point of 150 and viscosity of 35 cSt. An increase in pyrolysis experiments enabled large quantities of pyrolysis oil production. Co-pyrolysis of sewage sludge was carried out on laboratory scale with mixed wood, rapeseed and straw. It found that there was an increase in bio-oil quantity with rapeseed while co-pyrolysis with wood helped to mask the smell of the sludge pyrolysis oil. Engine test were successfully carried out in an old Lister engine with pyrolysis oil fractions of 30% and 50% blended with biodiesel. This indicates that these pyrolysis oil fractions can be used in similar engine types without any problems however long term effects in ordinary engines are unknown. An economic evaluation was carried out about the implementation of the intermediate pyrolysis process for electricity production in a CHP using the pyrolysis oil. The prices of electricity per kWh were found to be very high.
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Bajón, Fernández Yadira. "Carbon dioxide utilisation in anaerobic digesters as an on-site carbon revalorisation strategy." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9287.
Full textAbstract:
The increasing carbon footprint of the water and organic waste sectors has led to water utilities to voluntarily include carbon mitigation approaches within their strategic plans and to an increase in research aimed at mitigating carbon dioxide (CO2) emissions. Injection of CO2 in anaerobic digesters (ADs) for its bioconversion into methane (CH4) has been identified as a potential solution. However, previous literature provided limited knowledge of the carbon benefits obtainable and presented conflicting information regarding the mechanisms of CO2 utilisation. This thesis investigated the potential of injecting exogenous CO2 into ADs for its bioconversion into CH4 to reduce CO2 emissions from water and organic waste facilities. Batch laboratory scale and continuous pilot-scale ADs enriched with CO2 were operated. A substrate dependant response to exogenous CO2 was reported for the first time and potential CO2 savings of up to 34% and 11% were estimated for sewage sludge and food waste batch ADs, respectively, injected with CO2 before the digestion process. Higher benefits in CH4 production were observed in sewage sludge ADs than in food waste units. An up to 2.4 fold increase in CH4 production during the 24 hours following saturation with CO2 was obtained in sewage sludge units, while benefit was limited to 1.16 fold in food waste ADs. Microbial community analyses were performed to elucidate CO2 fate mechanisms. An increase of up to 80% in the activity of Methanosaetaceae (obligate acetoclastic methanogen) was observed in sewage sludge ADs periodically enriched with CO2. Methanosaetaceae was scarce (4.3±1.7%) in food waste units, which was attributed to an inhibitory concentration of ammonia (4 gL-1 NH4-N). Based on Archaea analyses and on monitoring hydrogen (H2) and volatile fatty acids (VFA) speciation dynamics in a pilot-scale AD, it was proposed that exogenous CO2 is reduced by homoacetogenesis (Wood-Ljungdahl mechanism) and the acetate generated by this route is converted to CH4 by acetoclastic methanogenesis. Gas to liquid mass transfer was identified as limiting of the amount of dissolved CO2 loaded to an AD and the complex rheology of anaerobically digested media as detrimental for transfer performance. An increase of apparent viscosity (μa) from 130 to 340 cPo (typical variability of sewage sludge) reduced gas transfer efficiency (GTE) by 6 percentage points. The use of bubble columns was identified as suitable for further scaled-up units. Injection of CO2 could be performed in the digestate recirculation loop of single phase ADs or in the first phase of two phase ADs (TPADs), with CO2 sourced from off-gas of biogas upgrading technologies. It has been demonstrated that bioconversion of CO2 in ADs can reduce carbon footprint and increase CH4 production, with the possibility of becoming an on-site carbon revalorisation strategy.
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Tuckwell, Rebecca. "The impact on receiving waters of pharmaceutical residues and antibiotic resistant faecal bacteria found in urban waste water effluents." Thesis, Middlesex University, 2015. http://eprints.mdx.ac.uk/18521/.
Full textAbstract:
Pharmaceuticals intended for human use are frequently detected in the aquatic environment. This is predominantly from their excretion following ingestion and subsequent discharge in domestic sewage. Wastewater treatment provides an opportunity to control their release to surface waters however, their removal is often incomplete. This thesis addresses this pharmaceutical pathway and the potential impact on the aquatic environment. The progress of bezafibrate, carbamazepine, ciprofloxacin and clarithromycin were monitored through the treatment stages (screened sewage, settled sewage and final effluent) of a large urban wastewater treatment plant (WWTP) and in surface waters up-stream and down-stream of the effluent discharge point. All except clarithromycin were detected in the screened sewage (369 – 2696 ng/L). Reductions in the pharmaceutical concentrations throughout the WWTP (22.5 – 94.3 %) indicate the removal of these compounds is variable. Bezafibrate and carbamazepine were observed at higher concentrations (67.5 - 305.5 ng/L) in surface water down-stream of the effluent discharge point compared to up-stream (31.0 – 116.7 ng/L). The presence of antibiotics in the environment may contribute to the dissemination of antibiotic resistance. The second part of this thesis monitors the prevalence of resistant faecal bacteria through WWTPs and in surface waters. Determination of antibiotic minimum inhibitory concentration (MIC) values for E.coli and E.faecium indicated that the WWTP did not influence the proportions of the resistant bacterial species. Elevated levels of E.coli with acquired ciprofloxacin resistance increased from not detectable in surface waters up-stream to 9.3% down-stream of the WWTP discharge point. The need for standardisation of the interpretation of MIC data is addressed. The potential of ciprofloxacin within surface water to select for ciprofloxacin resistant E.coli were investigated through microcosm studies in the third part of this study. A significant increase (p < 0.05) in the level of resistant E.coli was observed in microcosms exposed to ≥ 5 μg/L ciprofloxacin. At the ciprofloxacin levels typically detected in surface waters receiving treated effluent (<300 ng/L), the levels of resistance amongst E.coli were maintained.
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Kennedy-Walker, Ruth. "Planning for faecal sludge management in informal urban settlements of low-income countries : a study of Lusaka, Republic of Zambia." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/2856.
Full textAbstract:
Faecal Sludge Management is regarded as an affordable and viable option for providing sanitation services in complex informal urban settlements. This thesis examines to what extent current urban sanitation planning approaches and practices are suitable frameworks for achieving sustainable Faecal Sludge Management in informal settlements. The findings are based on a mixed methodology approach where primary data was collected from household level questionnaires (N=169) and a series of key informant interviews (N=35 at city and country level, N=14 at community level) during 2013 in Lusaka, Zambia. The development of a decision support tool that allows for the modelling, costing and comparison of various Faecal Sludge Management infrastructure and technology scenarios was also completed. The findings conclude that whilst many urban sanitation planning approaches exist, adaptation is required so that sustainable Faecal Sludge Management systems can be achieved in complex informal environments. Firstly, a more in depth understanding of social structures, dominant influences and their effect on service provision is required. In particular, an understanding of the role of politics, power, trust and history was shown to be vital. Insights from various decision-making domains including household, community, city and country level representatives was shown to be essential. Application of the developed decision support tool highlighted that obtaining accurate spatio-topological information on the existing sanitation and transport infrastructure networks and on the status and capacity of the containment, removal and transportation components of the Sanitation Value Chain is critical. These are required to ensure accurate long-term cost projections can be developed for various modelled scenarios, that comparisons can be made against other sanitation technologies and where appropriate, sustainable services can be implemented. This research bridges a gap in the sanitation sector by highlighting key socio-technical factors that need to be addressed in order to achieve sustainable sanitation provision for informal settlements in Zambia and beyond.
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Alebrahim, Meshaal. "Electrochemical removal of copper from monometallic solution and from bimettalic solution containing copper and zinc using packed-bed cathode." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809572/.
Full textAbstract:
Heavy metals are found as pollutant in many industrial waste waters. The toxicity of heavy metals has been known for many years and they belong to persistent toxic substances. Therefore, removal of these metals from industrial effluents represents an important challenge in order to avoid one of the major causes of water and soil pollution. The aim of this thesis was the efficient removal of two metal ions which are close to or more noble than hydrogen in the electromotive series (i. e. zinc and copper) from aqueous solutions that simulate industrial wastewater containing these two elements. The removal was done by employing an electrolytic reactor, provided with a 3-dimensional packed-bed cathode of carbon particles, operated in a continuous recirculation mode of flow. Firstly, the removal of copper from monometallic solution was dealt with where the effects of initial concentration of the metal, flow rate, applied current intensity and initial pH (pHo) on removal % and current efficiency of the metal removal were presented. Moreover, two experiments were performed at the same recirculation flow rate, pHo and initial concentration. In the first one the applied current was fixed at 7 A, while in the second one the applied current was decreased from 7 A to 3 A; by manually decreasing 1A every 15 minutes. The second mode of current application led to saving of 41.6 % in the electrical energy utilized for about 96 % removal of copper. Also, the removed copper could be recovered as Cu2O. Secondly, the removal of copper and zinc from bimetallic solutions - containing different mass ratios of Cu to Zn in the range from 0 - 80 % - were investigated. Experiments were carried out under galvanostatic condition. The initial pH was kept almost constant at a nominal value of 2.65 and the rate of flow of the treated solution was fixed at 0.065 L/s. It was found that: - The increase of Zn ratio did not affect the removal of copper negatively; but the presence of Cu with Zn did. - Increasing applied current intensity enhanced the removal of Cu and Zn while the current efficiency was decreased. - The effects of generation of hydrogen, anodic dissolution and IR drop are main reasons for decreasing current efficiency. Thirdly, a kinetic study was carried out in order to determine the order of the kinetics of metal-removal process and to shed light on how the operating parameters affect the value of rate constant. The study revealed that: - The removal of copper and Zn ions followed first order kinetics with respect to the concentration of the metal. - The apparent rate constant, k, of copper removal was found to depend on (F.R.), (pHo), (Co)Cu, (I) and the presence of Zn in the same solution with Cu. - The apparent rate constant, k, of Zn removal was found to be almost independent of the mass ratio of copper to zinc and increased with increasing applied current.
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Shana, Achame. "Application of an innovative process for improving mesophilic anaerobic digestion of sewage sludge." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809611/.
Full textAbstract:
Over the last 18 years, different sludge pre-treatment processes have been used to improve the performance of sewage sludge anaerobic digestion efficiency. Some of these pre-treatment technologies, notably the Thermal Hydrolysis Process (THP), has significantly increased the sludge throughput and allowed more efficient utilisation of treatment assets without adversely impacting the biology of the anaerobic digestion process. However, the expected increase in Volatile Solid reduction (VSr) and the consequent increase of biogas production have not been fully realised. Specifically, to address this poor performance when the THP process is used and to overcome its limitations, its application as an Intermediate Thermal Hydrolysis Process (ITHP) was studied. The ITHP process configuration consists of a first stage conventional Mesophilic Anaerobic Digestion (MAD) followed by THP and then a second stage MAD (i.e. MAD+THP+MAD). The main aims of this research were therefore to evaluate the impact of the ITHP configuration on an already digested sludge constituents, namely, carbohydrates, proteins and lipids degradation and the extent of their conversion to biogas. The sludge constituents’ degradation as a result of thermal hydrolysis and Anaerobic Digestion (AD) followed a stepwise process where the initial faster degradation was followed by a second stage slower degradation process. The sludge constituents’ degradation kinetic rate constants showed that the use of ITHP can further enhance the already digested sludge degradation reducing the sludge mass and increasing its conversion to biogas. Furthermore, the ITHP configuration showed a significant impact on sludge Extracellular Polymeric Substance (EPS) content. The results obtained from laboratory scale experiments showed that the ITHP process configuration resulted in an overall average VSr of 62% in comparison with the THP configuration which provided a VSr of 47%. As a result, the overall biogas production from the ITHP process was found to be in excess of 478 m3/tonne dry solids (TDS) fed, compared with 345 m3/tds feed from the THP digestion configuration.