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1
Whitehead, Alan Joseph. "Experimental culture of duckweed (Lemnaceae) for treatment of domestic sewage". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26665.
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The culture of the floating aquatic plant, duckweed (Lemna minor), as an agent of domestic sewage treatment was studied in a clarification lagoon at Duncan, British Columbia, during the summer of 1986. Duckweed was grown in plastic fabric tanks (3700 L volume, 1.85 m deep, 2.25 m² water surface area) receiving 290 L of sewage per day or 12.8 d hydraulic retention time. Three treatments were tested: cropped duckweed, uncropped duckweed, and no duckweed. Water quality, plant growth and tissue composition were monitored on the basis of weekly sampling.
Removals of VSS, COD, total-N and total-P were greater in the presence than in the absence of duckweed. Unmeasured imports of N and P masked the effect of plant uptake on reducing nutrient concentrations in the tank effluents. Sustainable duckweed yields were possible at both cropping rates, despite a severe infestation of aphids. Dry matter yields of 2.0 g/m².d and 6.4 g/m².d were obtained at the 15%/week and 50%/week cropping rates, respectively. Duckweed contained 6.1 - 6.4% N and 1.1 - 1.4% P (dry wt.). Plant harvest removed 0.14 g N/m².d and 0.03 g P/m².d at the 15%./week and 0.31 g N/m².d and 0.07 g P/m².d at the 50%/week cropping rates. Cropping increased the fraction of total-N and total-P loading that could be removed via plant uptake.
Performance of the experimental treatments is analyzed in the light of concentration data, mass balances, and mass flux estimations. Possible sources of unmeasured N and P imports are discussed, and recommendations for future research are provided. The results suggest that duckweed may hold promise under certain conditions as a means of polishing sewage lagoon effluent.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
2
Palazolo, Paul Joseph. "Use of genetic algorithms in bounded search for design of biological nitrification/denitrification waste treatment systems". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/32777.
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3
Morrison, Kirk Murray. "An assessment of the potential for biological phosphorus removal in Canadian wastewater treatment plants". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28507.
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This thesis assesses the potential for enhanced biological phosphorus (Bio-P) removal in Canadian wastewater treatment plants. Retrofit designs incorporating Bio-P removal were prepared for nine wastewater treatment plants across Canada, and were compared against chemical phosphorus removal technologies. Incremental capital and operating costs were calculated and internal rates of return (IRR's) for the capital investment required to install the Bio-P removal facilities were calculated. Based on these results, an assessment of the potential use for the technology in Canada is made.
Of the nine plants studied, results indicate that Bio-P removal is economically superior to chemical phosphorus removal for the Calgary Bonnybrook, Edmonton Gold Bar, Saskatoon Mclvor Weir and Regina wastewater treatment plants. In general, Bio-P removal appears to offer significant economic advantages to
plants located in Alberta and Saskatchewan because of the high
cost of phosphorus removal chemicals in these provinces. The
present low cost of phosphorus removal chemicals in Ontario and
Quebec likely limits the viability of Bio-P removal to large (greater than 300,000 m³/d), suitably configured plants. In British Columbia, where Bio-P removal is presently used in the Okanagan Valley, the absence of widespread provincial phosphorus removal standards makes future Bio-P installations unlikely. The potential for Bio-P removal in Manitoba, the Maritimes and the Yukon and Northwest Territories is again limited by the absence of phosphorus removal standards in these parts of Canada.
Results also indicate that the use of an anoxic/anaerobic/ aerobic process in the bioreactor, in conjunction with primary sludge fermentation through gravity thickening, is very applicable to Canadian plants and offers potential capital and operating cost savings relative to other Bio-P processes. The common practice of anaerobic sludge digestion, combined with sludge dewatering and land application, was found to be unfavourable from a Bio-P perspective unless the resulting supernatant/filtrate streams can be re-used or disposed of outside of the mainstream treatment process.
Through the preparation of the retrofit designs, it was
determined that certain aspects of Bio-P technology require additional research in order to optimize treatment plant design.
These include kinetic modelling; short SRT Bio-P removal; the
anorexic/anaerobic/aerobic process; the use of gravity thickening
for primary sludge fermentation; and phosphorus release during anaerobic digestion.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
4
Chen, Wen, i 陳雯. "A membrane bioreactor(MBR) for an innovative biological nitrogen removal process". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557959.
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5
Zhao, Kang, i 趙鈧. "An iron-facilitated chemical and biological process for phosphorus removal and recovery during wastewater treatment". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196027.
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Phosphorus (P) is an important pollutant of concern in wastewater that causes eutrophication and algal blooms in water body. On the other hand, P is a valuable natural resource for agricultural and industrial use. With the rapid depletion of mineral phosphorus on earth, there is a need to recover phosphorus from wastewater. In this study, a new chemical and biological process facilitated with iron dosing has been developed for P removal and recovery during wastewater treatment. The system consists of a main stream identical to the conventional activated sludge process in an aerobic sequencing batch reactor (SBR) for P removal and a side stream of sludge recirculation through an anaerobic SBR (AnSBR) for P release and recovery from the P-rich sludge.
In the aerobic SBR treating a synthetic domestic wastewater, Fe(III) (FeCl3) was dosed to remove P by precipitation and adsorption. Fe(III) dosing at a Fe/P molar ratio of 1.5:1 could reduce the P concentration from more than 10 mg/L to below 1 mg/L in the final effluent. Compared to other dosing periods, dosing Fe(III) right before the SBR settling could achieve the best result in sludge flocculation and P removal. Meanwhile, organic removal was well maintained as 90% of the chemical oxygen demand (COD) was degraded in the aerobic SBR. In the AnSBR, phosphate precipitated with ferric iron in the sludge was released owing to microbial Fe(III) reduction, and a positive correlation was found between the phosphate and ferrous iron concentrations in the sludge suspension. Chemical tests showed that significant P release from Fe(III)-P occurred only if the acidic condition and the reducing condition were combined. For the AnSBR sludge, a higher organic loading, lower pH and higher biomass concentration resulted in a higher level of Fe(III) reduction and P release. Organic acidogenesis prevailed in the reactor and lowered the pH to ~4.5, which facilitated the P release from the solid phase into the liquid phase. With a solids retention time (SRT) of 10 days, the anaerobic supernatant contained a phosphate concentration of up to 70 mg/L, while the settled sludge was returned to the aerobic SBR. The phosphate could be readily recovered from the supernatant with Fe-induced precipitation by aeration and pH adjustment, and the overall P recovery could be achieved at about 70%. In addition to the treatment performance, the speciation of P in the aerobic sludge and the anaerobic sludge also was investigated. A significant change in the immediately available P and the redox-sensitive P was found in the sludge through the aerobic-anaerobic cycle. Such chemical transformation is believed to be crucial to the P removal and recovery during the wastewater treatment process.published_or_final_version
Civil Engineering
Master
Master of Philosophy
6
Mao, Yanping, i 毛艷萍. "Biological removal of phosphorus and nitrogen from wastewater : new insights from metagenomic and metatranscriptomic approaches". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206323.
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Stephenson, Robert John. "A comparison of retained biomass anaerobic digester designs". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26740.
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The principles behind anaerobic digestion are fairly well understood, but the limits of application of each digester design are not known. Because there are significant differences in the properties of the many wastewaters requiring treatment optimal anaerobic digester performance requires the matching of feed characteristics to a digester design and mode of operation. No consensus has yet emerged on digester design, operating conditions or feed/digester match-ups.
In this study, three bench scale retained biomass anaerobic digester designs were examined for their response to a sequence of varied hydraulic retention times (HRTs) and influent wastewater concentrations. The digester designs studied were the upflow anaerobic filter, the upflow anaerobic expanded bed and the upflow anaerobic sludge bed. The wastewater was screened and diluted dairy cow manure obtained from the UBC dairy barn. The parameters monitored included the total and soluble chemical oxygen demand (TCOD and SCOD), volatile and suspended solids (VS and SS), total volatile fatty acids (VFAs), total Kjeldahl and ammonia nitrogen (TKN and NH₃-N), pH, biogas production, and the methane (CH₄) and carbon dioxide (C0₂) content of the biogas.
Wastewater treatment efficiencies, measured in terms of TCOD, SCOD, VS, and TVFA removals, and methane productivity and methane yield for each of the digester designs were examined for the range of the operating conditions.
The anaerobic filter digester effected a mean TCOD removal efficiency of 47% ± 14% at a mean 4.0 day HRT, 51% ± 9% at a mean 2.3 day HRT and 35% ± 11% at a mean 1.3 day HRT. The expanded bed digester effected a mean TCOD removal of 45% ± 15% at a mean 4.3 day HRT, 38% ± 12% at a mean 2.5 day HRT and 28% ± 9% at a mean 1.3 day HRT. The sludge bed digester effected a mean TCOD removal of 53% ± 9% at a mean 3.8 day HRT, 45% ± 12% at a mean 2.2 day HRT and 32% ± 10% at a mean 1.2 day HRT. For all three digesters, the difference in the treatment efficiency over the range of HRTs tested, from 5 to 1.25 days was not in proportion to the change in HRT. Methane productivity, measured against either the removal or addition of substrate in terms of TCOD, SCOD, VS and TVFA, demonstrated considerable variability. Methane production increased with both substrate addition and substrate removal. Methane yield increased with increasing HRT. The sludge bed digester generally exhibited the greatest but most variable methane yields. It produced 0.095 L CH₄/g VS added at a mean 3.8 day HRT and 0.037 L CH₄/g VS added at a mean 1.2 day HRT. The anaerobic filter delivered the greatest methane yield at the intermediate HRT, 0.044 L CH₄/g VS added at a mean 2.3 day HRT. The expanded bed demonstrated low methane yields over the range of feed strengths and HRTs tested.
Biogas composition averaged 62.1% methane and 17.1% carbon dioxide for the anaerobic filter, 43.6% methane and 5.3% carbon dioxide for the expanded bed. and 61.1% methane and 18.9% carbon dioxide for the sludge bed.Applied Science, Faculty of
Graduate
8
Yang, Ying, i 楊穎. "Characterization of broad-spectrum antibiotic resistance genes in wastewater treatment reactors through metagenomic approaches". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206338.
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9
Fradler, Katrin. "Improving bio-electricity production and waste stabilization in Microbial Fuel Cells". Thesis, University of South Wales, 2015. https://pure.southwales.ac.uk/en/studentthesis/improving-bioelectricity-production-and-waste-stabilization-in-microbial-fuel-cells(91c2db18-126b-4610-9bdb-42d7e42ae5e9).html.
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Biological wastewater treatment is typically aerobic and an energy intensive process, mainly due to the required aeration. Alternative sustainable processes are sought, such as Microbial fuel cells (MFC) where electrogenic bacteria can degrade organic matter present in the waste stream while simultaneously generating electricity. MFCs represent an emerging technology which may deliver the capability to reduce the pollution potential of low strength wastewaters (< 1500 mg COD l-1) while generating electricity which could be used to self-power the process. Waste streams high in volatile fatty acids (VFAs) with high conductivity are particularly preferred substrate streams. These may include the effluent from two stage bio-hydrogen and bio-methane systems, which in this study were treated in a four-module tubular MFC (V=1 l) to reduce the chemical oxygen demand (COD) and recover further energy from the substrate. It was shown that the power increased with increasing organic loading rate (0.036-0.572 g sCOD l-1 d-1), but COD removal efficiency decreased. The Coulombic Efficiency (CE) was found to decrease significantly at OLR ˃ 0.6 g sCOD l-1 d-1 and the energy recovery was 92.95 J l-1 (OLR=0.572 g sCOD l-1 d-1). Also, wash-down waters from a chilled food producing company were treated in the same tubular MFC, reducing the soluble COD content by 84.8%. The low power (≈ 30 W m-3) and cell potential (≈ 0.5 V) makes it necessary to investigate methods such as external capacitors, DC/DC converters or serial and parallel connection to improve the power quality. In this thesis, the use of the intrinsic capacitance was tested by switched mode, open and closed circuit (OC/CC) operation of a 2-module tubular MFC with high surface area carbon veil anode. The charge accumulated during OC and released when switched to CC was dependent on the external resistor (R = 100-3 kΩ) and duty cycle. Short period OC/CC switching further increased potential due to the pseudo-capacitance of the reactor, but only at the expense of energy efficiency, compared to continuous operation (CC) under constant load. Another approach to enhance the practical implementation of MFCs is integration with other processes such as reverse electrodialysis to increase MFC’s cell potential or e.g. desalination. In this study a MFC was integrated with supported liquid membrane technology (SLM) for the first time, for the removal of metal ions of wastewater. A three chamber reactor, with a common cathode/feed phase containing 400 mg Zn2+ l-1, enabled V the simultaneous treatment of organic- and heavy metal containing wastewaters. The MFC/SLM combination produces a synergistic effect which enhances the power performance of the MFC significantly; 0.233 mW compared to 0.094 mW in the control. It is shown that the 165±7 mV difference between the MFC/SLM system and the MFC control is partially attributable to the lower cathode pH in the integrated system experiment, the consequent lower activation overpotential and higher oxygen reduction potential. The system demonstrates that within 72 h, 93±4% of the zinc ions are removed from the feed phase. A further study, with continuously operated cathode/feed chamber (100 mg Zn2+ l-1), showed that an enhanced effect on increasing cell potential was possible and could also be maintained in continuous operation.
10
Casher, Thomas Christopher. "Biological excess phosphorus removal under high rate operating conditions in a suspended growth treatment process". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29464.
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The primary objective of this research was to determine if efficient biological phosphorus removal could be established under low sludge retention time of 2 days and a nominal hydraulic retention time of 4 to 6 hours. The two-stage Phoredox process was selected because of the practical application of retrofitting high rate treatment plants to achieve bio-P removal without the additional tankage required for an anoxic section and the additional expense of a recycle system.
It has been shown that nitrate recycled into the anaerobic reactor impacts on bio-P removal and the two-stage Phoredox process provides no control over nitrates entering the anaerobic reactor. Therefore a secondary objective of this research was to determine if a low sludge retention time mode of operation could be used as an effective way to prevent nitrification in the activated sludge treatment process.
Another objective was to observe mixed liquor settling characteristics of the two-stage Phoredox process operated under high rate conditions.
A pilot scale two-stage Phoredox activated sludge treatment process operating under high rate conditions was used to meet these objectives. The desired bio-P removal biomass was not observed under SRT operating conditions of 2, 3 and 5 days. Partway into the research a sludge bulking condition developed which was identified as filamentous
growth. On two occasions this severe filamentous growth resulted in the process failing and the system being restarted.
On one occasion after the system was restarted using a seed sludge from a three-stage Phoredox pilot plant, a bio-P removal biomass was present. This condition only lasted for a short period and ended as filamentous growth began to become dominant. The process failed because of this phenomenon.
The system was restarted using a seed sludge and again filamentous growth dominated. Chlorine addition was found to be the only method to control this phenomenon and was continued to the end of the research. The desired bio-P removal biomass was not observed even during the last period of the research when the SRT was increased to 8 days.
During this research a stable bio-P removal biomass was not established. For a short period a bio-P removal biomass was present but failed to persist. Nitrification never became established at any time. Sludge settleability was poor due to filamentous growth which developed partway into the research and was present throughout the remainder of the study. Chlorine addition was the only method found that remedied this settling problem.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
11
Lee, N. P. (Nelson Paul). "The affect of anaerobic volume reduction on the University of Cape Town (UCT) biological phosphorus removal process". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29631.
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The objective of this research was to optimize the bio-P process as applied to a weak sewage with respect to HRT in each of the process zones. This goal was to be achieved by changing the HRT of the various zones with all other operating characteristics being held constant.
The experimental work during this study involved two initially identical process trains operated in the University of Cape Town (UCT) mode. The aerobic zones of both trains were divided into four equal sized complete-mix cells to allow observations of phosphate uptake and poly-β-hydroxyalkanoate (PHA) consumption under aerobic conditions. After steady-state was established, the anaerobic HRT was reduced to 50% of the original value in the experimental module by reducing the anaerobic reactor volume. At the same time, the mixed liquor of both trains was drained, mixed and reapportioned to the two processes, thereby assuring equivalent starting conditions.
Results of this study showed that both processes performed identically prior to the anaerobic HRT change. After the anaerobic HRT change, there was a forty day period where P removal and effluent P were the same in both process trains. This was so, even though the anaerobic P release was considerably less in the experimental module. Subsequently, a change in influent sewage type corresponded to a change in P removal and effluent P in the two process trains. An examination of the process parameters showed that the anoxic zone of the experimental module, after the anaerobic HRT change and the sewage change, consistently removed less P or released more P than
in the control module. As a result, the control module out-performed the experimental module. Batch tests and tests to better characterize the influent sewage were then conducted in an attempt to determine the reasons for the different P removal characteristics.
Under the test conditions, it appeared that the original anaerobic HRT was excessive. This was preferable to an insufficient anaerobic HRT, such as in the experimental module, however. The anoxic zone may have been too large, too small or just right for optimum P removal depending on the influent sewage characteristics. Optimizing the bio-P process by reducing the aerobic zone HRT appeared to have the greatest potential.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
12
Russo, Stephen Leonard. "Anaerobic treatment of a paper plant effluent". Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/21988.
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The objective of this study was to investigate the anaerobic biological treatment of an organic-bearing wastewater from a particular paper manufacturing process at laboratory scale. The process produces paper by re-pulping waste paper. Effluent from the process has a Chemical Oxygen Demand (COD) concentration of approximately 4500 mg/l with a sulphate content of approximately 300 mg SO₄²⁻/l. The upflow anaerobic sludge bed (UASB) reactor was selected for the study. Important information derived from the laboratory treatability study was: (l) the extent of COD removal possible; (2) the effluent quality; (3) the maximum COD leading rate (kgCOD/m³ reactor/day) which can be achieved while maintaining reasonable COD removal, and the influence on loading rate of temperature: (4) the nature of the sludge produced in the reactor with particular reference to the extent of pelletisation: and (5) the effect of reactor effluent recycling on alkalinity requirements.
13
Sun, Feiyun, i 孙飞云. "A membrane bioreactor (MBR) for a biological nutrient removal system: treatment performance, membrane foulingmechanism and its mitigation strategy". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44903856.
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14
Wells, Charles Digby. "Tertiary treatment in integrated algal ponding systems". Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1006162.
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Inadequate sanitation is one of the leading causes of water pollution and consequently illness in many underdeveloped countries, including South Africa and, specifically, the Eastern Cape Province, where cholera has become endemic. As modern wastewater treatment processes are often energy intensive and expensive, they are not suitable for use in these areas. There is thus a need to develop more sustainable wastewater treatment technologies for application in smaller communities. The integrated algal ponding system (IAPS) was identified as a possible solution to this wastewater management problem and was investigated for adaptation to local conditions, at the Rhodes University Environmental Experimental Field Station in Grahamstown, South Africa. The system was monitored over a period of nine years, with various configuration adjustments of the high rate algal pond (HRAP) unit operation investigated. Under standard operating conditions, the system was able to achieve levels of nutrient and organic removal comparable with conventional wastewater treatment works. The mean nitrate level achieved in the effluent was below the 15mg.l-1 South African discharge standard, however, nitrate removal in the IAPS was found to be inconsistent. Although the system was unable to sustain chemical oxygen demand (COD) removal to below the 75mg.l-1 South African discharge standard, a removal rate of 87% was recorded, with the residual COD remaining in the form of algal biomass. Previous studies in the Eastern Cape Province have shown that few small wastewater treatment works produce effluent that meets the microbial count specification. Therefore, in addition to the collation of IAPS data from the entire nine year monitoring period, this study also investigated the use of the HRAP as an independent unit operation for disinfection of effluent from small sewage plants. It was demonstrated that the independent high rate algal pond (IHRAP) as a free standing unit operation could consistently produce water with Escherichia coli counts of 0cfu.100ml-1. The observed effect was related to a number of possible conditions prevailing in the system, including elevated pH, sunlight and dissolved oxygen. It was also found that the IHRAP greatly enhanced the nutrient removal capabilities of the conventional IAPS, making it possible to reliably and consistently maintain phosphate and ammonium levels in the final effluent to below 5mg.l-1 and 2mg.l-1 respectively (South African discharge standards are 10mg.l-1 and 3mg.l-1 in each case). The quality of the final effluent produced by the optimisation of the IAPS would allow it to be used for irrigation, thereby providing an alternative water source in water stressed areas. The system also proved to be exceptionally robust and data collected during periods of intensive and low management regimes were broadly comparable. Results of the 9 year study have demonstrated reliable performance of the IAPS and its use an appropriate, sustainable wastewater treatment option for small communities.
15
Yan, Qingmei, i 嚴慶梅. "Biological nitrogen removal of saline wastewater by ammoniumoxidizers". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42182116.
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Li, Yun, i 李贇. "Formation and stability of aerobic granular sludge in biological wastewater treatment". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197519.
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Aerobic sludge granulation is a new technology that has been developed for biological wastewater treatment. Compared with conventional activated sludge, aerobic granules allow better sludge-water separation and a higher biomass concentration. However, the mechanism of the transformation from sludge flocs to granular sludge under the aerobic condition is still unclear. Deterioration of aerobic granules in long-term operation is also a concern for its scale-up application. The present study was conducted to investigate the crucial factors for aerobic granulation and its underlying mechanism. In addition, the stability of aerobic granules under unfavorable conditions and the recovery of deteriorated granules in bioreactors were also studied.
For formation of aerobic granules, gelation-facilitated biofilm growth was proposed as a new mechanism for the granulation process. Simulation of granule formation was performed in a well-controlled chemical system to provide an experimental proof for the proposed aerobic granulation theory. Granule formation was achieved in a particle suspension with latex microspheres for bacterial cells and alginate and peptone for extracellular polymeric substances (EPS), together with the cation addition and floc discharge. In the mixture with the dosing of alginate and a small amount of peptone, artificial gels and granules could be well formed, and the artificial granules share the similar micro-structure as the aerobic bacterial granules. However, as the dose of peptone increased, gels were not formed and only large particle flocs were produced. The formation of artificial granules proves that effective EPS interactions with cations and the subsequent gelation are crucial to aerobic granulation in bioreactors. In relation to granulation, the effect of the substrate feeding pattern on the microbial yield was tested. The results show that the bioreactor with a more frequent substrate feeding interval had a lower sludge yield than the reactor (0.45 vs. 0.55) with a less frequent feeding. The sludge fed less frequently was able to store more substrates as intracellular substances, resulting in more biomass growth. Moreover, a long feeding interval would force the biomass into the feast-famine regime, which was found to enhance microbial growth and granulation, producing granules with a compact and stable structure.
For the stability of aerobic granules, various factors that would been countered in biological wastewater treatment were experimented. The results show that granules deteriorated in structure under unfavorable conditions, such as a low solution pH (pH~6.0), a high loading rate, and feed of starch instead of glucose into the bioreactors. In some deterioration cases, filamentous bacterial growth became more dominant and the granules became loose and fluffy flocs. Compared to mature granules, fresh granules were less stable and more vulnerable to the unfavorable conditions. As the granules deteriorated in structure, their surface roughness values increased considerably from 35 or less to more than 230. Under a favorable condition with a feed of sodium acetate, the deteriorated granules could be recovered in some reactors. However, deterioration of the granules caused by filamentous growth at a low pH or high loading rate could hardly be recovered.published_or_final_version
Civil Engineering
Master
Master of Philosophy
17
Chung, King Chuen. "Biological processes involved in two wetland plants and their associated bacteria for the treatment of municipal wastewaters". HKBU Institutional Repository, 2009. http://repository.hkbu.edu.hk/etd_ra/1005.
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Enongene, Godlove Nkwelle. "The enzymology of enhanced hydrolysis within the biosulphidogenic recycling sludge bed reactor (RSBR)". Thesis, Rhodes University, 2004. http://hdl.handle.net/10962/d1015744.
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The hydrolysis of complex organic heteropolymers contained in municipal wastewater to simpler monomers by extracellular hydrolytic enzymes is generally considered the rate-limiting step of the biodegradation process. Previous studies of the Recycling Sludge Bed Reactor (RSBR) revealed that the hydrolysis of complex particulate organics, such as those contained in primary sludge (PS), was enhanced under anaerobic biosulphidogenic conditions. Although the mechanism was not fully understood, it appeared to involve the interaction of sulfide and sludge flocs. The current study was conducted using a 3500 ml laboratory-scale RSBR fed sieved PS at a loading rate of 0.5 kg COD/m³.day and an initial chemical oxygen demand (COD) to sulfate ratio (COD:SO₄) of 1:1. There was no significant accumulation of undigested sludge in the reactor over the 60-day experimental period and the quantity of SO₄ reduced indicated that the yield of soluble products from PS was at least as high as those reported previously for this system (> 50%). In the current study, the specific activities of a range of extracellular hydrolytic enzymes (L-alanine aminopeptidase, L-leucine aminopeptidase, arylsulphatase, α-glucosidase, β- glucosidase, protease and lipase) were monitored in a sulfide gradient within a biosulphidogenic RSBR. Data obtained indicated that the specific enzymatic activities increased with the depth of the RSBR and also correlated with a number of the physicochemical parameters including sulfide, alkalinity and sulfate. The activities of α- glucosidase and β-glucosidase were higher than that of the other enzymes studied. Lipase activity was relatively low and studies conducted on the enzyme-enzyme interaction using specific enzyme inhibitors indicated that lipases were probably being digested by the proteases. Further studies to determine the impact of sulfide on the enzymes, showed an increase in the enzyme activity with increasing sulfide concentration. Possible direct affects were investigated by looking for changes in the Michaelis constant (Km) and the maximal velocity (Vmax) of the crude enzymes with varying sulfide concentrations (250, 400 and 500 mg/l) using natural and synthetic substrates. The results showed no significant difference in both the Km and the Vmax for any of the hydrolytic enzymes except for the protease. The latter showed a statistically significant increase in the Km with increasing sulfide concentration. Although this indicated a direct interaction, this difference was not large enough to be of biochemical significance and was consequently not solely responsible for the enhanced hydrolysis observed in the RSBR. Investigation into the floc characteristics indicated that the biosulphidogenic RSBR flocs were generally small in size and became more dendritic with the depth of the RSBR. Based on the above data, the previously proposed descriptive models of enhanced hydrolysis of particulate organic matter in a biosulphidogenic RSBR has been revised. It is thought that the effect of sulfide on the hydrolysis step is primarily indirect and that the reduction in floc size and alteration of the floc shape to a more dendritic form is central to the success of the process.
19
McMillan, Morgan. "Biological treatment of source separated urine in a sequencing batch reactor". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96047.
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Thesis (MScEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: Urine contains up to 80% of nitrogen, 50 % of phosphates and 90 % of potassium of the total load in domestic wastewater but makes up less than 1% of the total volume (Larsen et al., 1996). The source separation and separate treatment of this concentrated waste stream can have various downstream advantages on wastewater infrastructure and treated effluent quality. The handling of undiluted source separated urine however poses various challenges from the origin onward. The urine has to be transported to a point of discharge and ultimately has to be treated in order to remove the high loads of organics and nutrients. Wilsenach (2006) proposed onsite treatment of source separated urine in a sequencing batch reactor before discharging it into the sewer system. This study focused on the treatment of urine in a sequencing batch reactor (SBR) primarily for removal of nitrogen through biological nitrification-denitrification. The aim of the study was to determine nitrification and denitrification kinetics of undiluted urine as well as quantification of the stoichiometric reactions. A further objective was to develop a mathematical model for nitrification and denitrification of urine using experimental data from the SBR. The SBR was operated in 24 hour cycles consisting of an anoxic denitrification phase and an aerobic nitrification phase. The sludge age and hydraulic retention time was maintained at 20 days. pH was controlled through influent urine during volume exchanges. Undiluted urine for the study was obtained from a source separation system at an office at the CSIR campus in Stellenbosch. Conditions in the reactor were monitored by online temperature, pH and ORP probes. The OUR of the system was also measured online. One of the main challenges in the biological treatment of undiluted urine was the inhibiting effect thereof on nitrification rate. The anoxic mass fraction was therefore limited to 17 % in order to allow longer aerobic phases and compensate for the slow nitrification rates. Volume exchanges were also limited to 5% of the reactor volume in order to maintain pH within optimal range. Samples from the reactor were analysed for TKN, FSA-N, nitrite-N, nitrate-N and COD. From the analytical results it was concluded that ammonia oxidising organisms and nitrite oxidising organism were inhibited as significant concentrations of ammonia-N and nitrite-N were present in the effluent. It was also concluded that nitrite oxidising organisms were more severely inhibited than ammonia oxidising organisms as nitrate-N was present in very low concentrations in the effluent and in some instances not present at all. Ultimately the experimental system was capable of converting 66% of FSA-N to nitrite- N/nitrate-N of which 44% was converted to nitrogen gas. On average 48% of COD was removed. A mathematical model was developed in spreadsheet form using a time step integration method. The model was calibrated with measured online data from the SBR and evaluated by comparing the output with analytical results. Biomass in the model was devised into three groups, namely heterotrophic organisms, autotrophic ammonia oxidisers (AAO) and autotrophic nitrite oxidisers (ANO). It was found that biomass fractionation into these three groups of 40% heterotrophs, 30% AAO and 30% ANO produced best results. The model was capable of reproducing the general trends of changes in substrate for the various organism groups as well as OUR. The accuracy of the results however varies and nearexact results were not always achievable. The model has some imperfections and limitations but provides a basis for future work.
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Cao, Keping. "Simultaneous Removal of Carbon and Nitrogen by Using a Single Bioreactor for Land Limited Application". Thesis, Water Resources Research Center, University of Hawaii at Manoa, 1998. http://hdl.handle.net/10125/22230.
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An Entrapped-Mixed-Microbial-Cell (EMMC) process was investigated for its simultaneous removal of carbon and nitrogen in a single bioreactor with the influent COD/N ratio varying from 4 to 15 and influent alkalinity of 140 mg CaCO3/L and 230 mg CaCO3/L. The reactor was operated with alternate schedules of intermittent aeration. Two different sizes of carriers (10 * 10 * 10 mm3 and 20 * 20 * 20 mm3) were studied.
The medium carrier (10 * 10 * 10 mm3) system presents higher nitrogen removal and COD removal compared to the large carrier system. The nitrogen removal efficiency is related to the ratio of COD/N in the influent. With the increase of the COD/N ration in the influent, the nitrogen removal efficiency is increased.
The average reductions of nitrogen were over 92% and the average reductions of SCOD and BOD5 are over 95% and 97%, respectively, in the medium carrier system. This is operated at the HRT of 12 hours and 0.5 hour aeration and 2 hours of non-aeration, and the COD/N ratio of 15 in the influent. Changing alkalinity from 140 to 230 mg CaCO3/L has no effect in both large and medium carriers for the nitrogen removal efficiency.
The pH, oxidation – reduction potential (ORP) and dissolved oxygen (DO) were used to monitor the biological nitrogen removal. It was found that the ORP (range from -100 to 300 mV) can be used to provide better effluent quality measured as total-nitrogen of less than 10 mg/L. Also, the impact of influent COD/N ratio on the effluent quality (measured as Inorg.-nitrogen) for the EMMC process is very important.
Compared to other two compact biological wastewater treatment processes, membrane bioreactor (MBR) and moving bed biofilm reactor (MBBR), the EMMC process with the intermittent aeration has higher removal efficiencies of carbon and nitrogen, easier operation, lower O&M cost, lower energy requirement, and more compact. The total cost requirement is less than $3.27 per 1000 gallons (3.785 m 3) of treated settled domestic sewage per day. It is apparent that the EMMC process is technically feasible for the simultaneous removal of carbon and nitrogen under the operation on a schedule of intermittent aeration and suitable to be used for replacement or upgrading of existing treatment plant at land limited area.
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Bocken, Stephan. "D.O. control and O.U.R. estimation in the activated sludge process". Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/22156.
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au, rkurup@murdoch edu, i Rajendra Kurup. "An experimental research on application of sub-surface flow constructed wetlands for meat processing industry effluent treatment and nutrient removal". Murdoch University, 2007. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20070717.142408.
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Meat processing industries produce large volumes of high strength wastewater.
Conventional technologies used in Australia and similar countries for treatment of
effluent from meat processing and similar industries, such as wineries and processed
food industry, are treatment ponds with or without a mechanical treatment system.
A properly designed activated sludge treatment system would be capable of biological
removal of phosphorus and nitrogen in addition to BOD5. These systems, however,
require substantial electrical power, skilled operational support and produce large
quantities of biosolids or sludge which require further on-site treatment or off site
disposal. Application of sub-surface flow constructed wetland (SSF-CW) systems could
provide a sustainable solution for treatment of meat processing industry effluent and
other similar high strength wastewaters. There are, however, only very limited studies
on application of SSF-CW for secondary treatment of high strength wastewaters.
Although there have been a number of cases where SSF-CW have been used as the
secondary treatment unit for municipal wastewater, this technology has not still become
a common practice for the same purpose in Australia. Most of the applications are for
either polishing of secondary or tertiary treated municipal wastewater or for greywater
treatment.
This research was funded by National Meat Industry Advisory Council (MINTRAC).
Sustainable wastewater treatment has been taken up as a very important issue by meat
industry. The industry provides Ph.D research scholarships through MINTRAC to
develop new technologies for wastewater treatment and nutrient removal from meat
processing effluent.
The main objective of the research was to develop process engineering design
parameters for sub-surface flow constructed wetland (SSF-CW) with Monto vetiver
(Vetiveria zizanioides recently reclassified as Chrysopogon zizanioides) as the emergent
vegetation for treatment of high strength, nutrient rich wastewater. The study also
investigated the phosphorus retention properties of pea gravel for use in SSF-CW
system as bed media or as an external phosphorus removal system for meat processing
industry effluent. In addition, chemical methods for phosphorus removal from meat
processing industry effluent were also investigated.
The thesis is based on experimental research. The research consisted of three types of
experimental set up; a) using two laboratory experimental SSF-CW reactors (one with
vetiver grass and the other reactor with no vegetation) in a greenhouse with batch
feeding of artificial wastewater that simulates meat industry effluent, b) experiment with
pea gravel of different particle sizes and solutions of different phosphorus (P)
concentrations in a constant temperature room, c) laboratory experiment using actual
meat processing industry effluent with alum and sodium aluminate for P removal.
The structure of the thesis is as follows. Following the Introduction is the section of
Literature Review, then sections on the experiments that follow a journal paper format,
followed by a General Discussion, Conclusions and Recommendations. A list of
references is provided at the end of the thesis.
The literature review section has four chapters (Chapter 2 to Chapter 5). Chapter 2
describes a review of meat processing industry effluent characteristics and current
treatment technologies. Chapter 3 is a critical review of current literature on COD
removal using sub-surface flow constructed wetlands (SSF-CW). Chapter 4 and 5
describe a review of various processes and models on the fate of nitrogen and
phosphorus in SSF-CW system respectively.
Chapters 6 to 10 deal with experimental research part of the thesis. Chapters, 6, 7 and 8
share a common methodology section which is described in Chapter 6. Results of the
batch experiments with the laboratory SSF-CW systems on COD removal, nitrogen
removal and phosphorus retention are discussed in Chapters 6, 7 and 8 respectively.
Chapter 9 explains a detailed experimental study on phosphorus adsorption dynamics of
pea gravel. Chapter 10 discusses the results on experiments using sodium aluminate and
aluminium sulphate for P removal from meat processing industry effluent as an alternate
P removal method for such effluent.
An overview of the major results of the experimental section is discussed in chapter 11,
in the General Discussion section. Conclusions and Recommendations of the research
are provided in Chapter 12.
In this study, it was observed that Monto vetiver grass performed better during
nitrification than in denitrification, where the plant did not survive. Ammonium N
removal followed a first order decay in both vegetated and un-vegetated experimental
SSF-CW system with average removal ranging from 40 to 60 % of the influent.
Denitrification was found to be the pathway for nitrate removal. As long as the carbon
source was available, the denitrification followed a first order exponential decay, with
over 80% of nitrate was removed in 48 hours. Vetiver grass sustained elevated
ammonium levels of approximately 200 mg/L or more, however it was under stress
during denitrification and it eventually died.
The experimental SSF-CW systems with pea gravel as bed media could effectively
retain soluble reactive phosphorus (SRP) in the wetland cells during experiments of
COD reduction and nitrification (with ammonia and high COD input). However, during
denitrification study, both experimental SSF-CW cells did not show significant removal
of SRP from wastewater. The vegetated cell removed nearly 50% of the input SRP,
however, the un-vegetated cell did not show any trend for SRP removal, and in some
cases the effluent SRP was nearly 90% of the input value.
The role of Monto vetiver grass for N and P removal was found to be very minor and
this study concluded that nutrient removal (N & P) by plant uptake could be neglected
in the design of SSF-CW system with Monto vetiver grass.
Adsorption is the major mechanism for P removal from the experimental SSF-CW
systems, where pea gravel was used as bed media. The P adsorption capacity of pea
gravel increased with decrease in particle size. For 16 to 18 mm, the Langmuir
adsorption maximum was 99 mg/kg, whereas for very fine pea gravel powder (<150
ìm) the maximum adsorption observed experimentally was 3950 mg/kg. In a typical
wetland with pea gravel as bed media for meat processing industry, the media would be
capable of P retention for about 2 to 3 years of operation. Supplementary chemical
removal method is needed for sustainable P removal once the adsorption maximum of
wetland cell is reached.
A chemical P removal system using liquid alum and NaOH for pH stabilisation is more
appropriate than sodium aluminate. Application of sodium aluminate for P removal for
meat processing industry effluent is found to be less effective as it would need higher
dosage, longer settling period, coloured supernatant, acid addition for pH adjustment.
Liquid alum application rate is recommended to be between a molar ratio of Al: P of 3
for TP value of <1 mg/L in the treated effluent.
This research study concludes that horizontal flow SSF-CW system with Monto vetiver
grass is suitable for COD removal and nitrification from high strength wastewater.
Current design equation of horizontal flow SSF-CW system is mostly plug flow
exponential decay method, but in this study, it has been concluded that retarded first
order rate constant is the most appropriate design method for horizontal flow SSF-CW
system for COD removal.
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Liu, Hong, i 劉紅. "Bio-hydrogen production from carbohydrate-containing wastewater". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31244518.
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Cameron, Kimberley A. "The efficiency and mechanisms for pollutant removal in biological wastewater treatment systems /". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33724.
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The research project was initiated to refine the knowledge available on the treatment of rural municipal wastewater by constructed wetlands. Field and laboratory studies were conducted to determine the treatment capacity of a constructed wetland system and to determine a substrate that would be most efficient as a phosphorus adsorption filter. The wetland system consisted of three free-water surface cells, three blast furnace slag filters and a vegetated filter strip, treating municipal wastewater. Bimonthly water samples at the inlet and outlet of each component of the wetland system were analysed for biochemical oxygen demand, nitrate and nitrite, ammonia and ammonium, total Kjeldahl nitrogen, total suspended solids, total phosphorus, ortho-phosphate, fecal coliforms and E. coli. Phosphorus and nitrogen concentrations were determined in the sediment, plant tissue and water column of the free-surface wetland cells. The free-surface wetland cells achieved removals as follows: ammonia and ammonium (52%), total Kjeldahl nitrogen (37%), total suspended solids (93%), total phosphorus (90%) and ortho-phosphate (82%). The vegetated filter strip achieved removals as follows: ammonia and ammonium (28%), total Kjeldahl nitrogen (11%), total suspended solids (22%), total phosphorus (5%) and ortho-phosphate (0%). The slag filters reduced total phosphorus by more than 99%. Phosphorus adsorption measurements were conducted on slag, calcite and shale. Slag was found to be the most effective at removing phosphate.
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Brannan, Kenneth P. "Substrate stabilization in the anaerobic stage of a biological phosphorus removal system". Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49992.
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Chan, Yue-ping, i 陳裕萍. "Simulation and analysis of biological wastewater treatment processes using GPS-X". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31255437.
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Clark, Stewart James. "The independent high rate algal pond as a unit operation in tertiary wastewater treatment". Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1007805.
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The development of the High Rate Algal Pond (HRAP) as an independent tertiary treatment unit operation for phosphate and nitrate removal is reported. A novel Integrated Algal Ponding System (lAPS) design is proposed for nutrient removal from the effluents of both a conventional domestic sewage treatment plant and from an Advanced Integrated Wastewater Ponding System (AIWPS). The viability of an independently operated HRAP has been identified and termed the Independent High Rate Algal Pond (l-HRAP). A 500 m² pilot 1- HRAP was operated in such a way as to facilitate the precipitation of calcium phosphate, known to be controlled by pH (greater than 9.4) and resulting in final phosphate levels of less than 1 mg.L⁻¹ as P0₄-P. The incorporation of the I-HRAP into a denitrification process was also investigated. Continuously fed column reactors, utilising algal biomass as a carbon source, showed that the heterotrophic bacterial community dominant in the anaerobic algal sludge were denitrifying the nitrate in the feed. It was demonstrated that as the cultures were stressed (using increased nitrate concentrations, anaerobiosis and light starvation) total polysaccharide (TPS) concentrations increased, with a notable increase 111 the exopolysaccharide (EPS) fraction. These experiments corroborated the hypothesis that harvested microalgal biomass can be manipulated to produce, and release, exopolymeric substances under stress conditions, and which may serve as carbon source for denitrification. In both batch flask studies and in laboratory-scale reactor systems, harvested microalgal biomass from an HRAP was shown to produce exopolymeric substances under stress conditions. Initial high loading-rates of greater than 20 mg.L⁻¹ NO₃-N resulted in double the amount of exopolysaccharide production than in flasks with initial low loading-rates (less than 5 mg.L⁻¹ NO₃-N). Making use of an upflow anaerobic sludge blanket-type degrading-bed reactor, and an anaerobic, flooded trickle filter (ANTRIC) receiving HRAP effluent, the relationship between denitrification and the changes in polysaccharide content was investigated. This phenomenon has considerable beneficial implications in biological wastewater treatment systems where high nitrate concentration in the final effluent is a potential mitigating factor. Identification of the heterotrophic bacteria active in the denitrification process was attempted. This study presents a first report on the development and operation of the I-HRAP and has been followed by a technical-scale pilot plant evaluation of the process in the tertiary treatment of domestic wastewaters.
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Westensee, Dirk Karl. "Post-treatment technologies for integrated algal pond systems". Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1018180.
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Integrated Algae Pond Systems (IAPS) are a derivation of the Oswald designed Algal Integrated Wastewater Pond Systems (AIWPS®) and combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. IAPS technology was introduced to South Africa in 1996 and a pilot plant designed and commissioned at the Belmont Valley WWTW in Grahamstown. The system has been in continual use since implementation and affords a secondarily treated water for reclamation according to its design specifications which most closely resemble those of the AIWPS® Advanced Secondary Process developed by Oswald. As a consequence, and as might be expected, while the technology performed well and delivered a final effluent superior to most pond systems deployed in South Africa it was unable to meet The Department of Water Affairs General Standard for nutrient removal and effluent discharge. The work described in this thesis involved the design, construction, and evaluation of several tertiary treatment units (TTU') for incorporation into the IAPS process design. Included were; Maturation Ponds (MP), Slow Sand Filter (SSF) and Rock Filters (RF). Three MP's were constructed in series with a 12 day retention time and operated in parallel with a two-layered SSF and a three-stage RF. Water quality of the effluent emerging from each of these TTU's was monitored over a 10 month period. Significant decreases in the chemical oxygen demand (COD), ammonium-N, phosphate-P, nitrate-N, faecal coliforms (FC) and total coliforms (TC) were achieved by these TTU's. On average, throughout the testing period, water quality was within the statutory limit for discharge to a water course that is not a listed water course, with the exception of the total suspended solids (TSS). The RF was determined as the most suitable TTU for commercial use due to production of a better quality water, smaller footprint, lower construction costs and less maintenance required. From the results of this investigation it is concluded that commercial deployment of IAPS for the treatment of municipal sewage requires the inclusion of a suitable TTU. Furthermore, and based on the findings presented, RF appears most appropriate to ensure that quality of the final effluent meets the standard for discharge.
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Zhou, Yanmin, i 周延敏. "Impacts of temperature and salinity on nitrification rate and microbial community in laboratory scale sequencing batch reactors(SBRs)". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47050718.
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Hijazi, Amal. "Nitrogen and phosphorus transformations in fixed-film biofilters subjected to aeration/no-aeration cycles". Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36070/6/36070_Digitised_Thesis.pdf.
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Despite recent developments in fixed-film combined biological nutrients removal (BNR) technology; fixed-film systems (i.e., biofilters), are still at the early stages of development and their application has been limited to a few laboratory-scale experiments. Achieving enhanced biological phosphorus removal in fixed-film systems requires exposing the micro-organisms and the waste stream to alternating anaerobic/aerobic or anaerobic/anoxic conditions in cycles. The concept of cycle duration (CD) as a process control parameter is unique to fixed-film BNR systems, has not been previously investigated, and can be used to optimise the performance of such systems. The CD refers to the elapsed time before the biomass is re-exposed to the same environmental conditions in cycles.
Fixed-film systems offer many advantages over suspended growth systems such as reduced operating costs, simplicity of operation, absence of sludge recycling problems, and compactness. The control of nutrient discharges to water bodies, improves water quality, fish production, and allow water reuse. The main objective of this study was to develop a fundamental understanding of the effect of CD on the transformations of nutrients in fixed-film biofilter systems subjected to alternating aeration I no-aeration cycles A fixed-film biofilter system consisting of three up-flow biofilters connected in series was developed and tested. The first and third biofilters were operated in a cyclic mode in which the biomass was subjected to aeration/no-aeration cycles. The influent wastewater was simulated aquaculture whose composition was based on actual water quality parameters of aquacuture wastewater from a prawn grow-out facility. The influent contained 8.5 - 9:3 mg!L a111monia-N, 8.5- 8.7 mg/L phosphate-P, and 45- 50 mg!L acetate. Two independent studies were conducted at two biofiltration rates to evaluate and confirm the effect of CD on nutrient transformations in the biofilter system for application in aquaculture: A third study was conducted to enhance denitrification in the system using an external carbon- source at a rate varying from 0-24 ml/min. The CD was varied in the range of0.25- 120 hours for the first two studies and fixed at 12 hours for the third study.
This study identified the CD as an important process control parameter that can be used to optimise the performance of full-scale fixed-film systems for BNR which represents a novel contribution in this field of research. The CD resulted in environmental conditions that inhibited or enhanced nutrient transformations. The effect of CD on BNR in fixed-film systems in terms of phosphorus biomass saturation and depletion has been established. Short CDs did not permit the establishment of anaerobic activity in the un-aerated biofilter and, thus, inhibited phosphorus release.
Long CDs resulted in extended anaerobic activity and, thus, resulted in active phosphorus release. Long CDs, however, resulted in depleting the biomass phosphorus reservoir in the releasing biofilter and saturating the biomass phosphorus reservoir in the up-taking biofilter in the cycle. This phosphorus biomass saturation/depletion phenomenon imposes a practical limit on how short or long the CD can be. The length of the CD should be somewhere just before saturation or depletion occur and for the system tested, the optimal CD was 12 hours for the biofiltration rates tested.
The system achieved limited net phosphorus removal due to the limited sludge wasting and lack of external carbon supply during phosphorus uptake. The phosphorus saturation and depletion reflected the need to extract phosphorus from the phosphorus-rich micro-organisms, for example, through back-washing. The major challenges of achieving phosphorus removal in the system included: (I) overcoming the deterioration in the performance of the system during the transition period following the start of each new cycle; and (2) wasting excess phosphorus-saturated biomass following the aeration cycle. Denitrification occurred in poorly aerated sections of the third biofilter and generally declined as the CD increased and as the time progressed in the individual cycle. Denitrification and phosphorus uptake were supplied by an internal organic carbon source, and the addition of an external carbon source (acetate) to the third biofilter resulted in improved denitrification efficiency in the system from 18.4 without supplemental carbon to 88.7% when the carbon dose reached 24 mL/min The removal of TOC and nitrification improved as the CD increased, as a result of the reduction in the frequency of transition periods between the cycles. A conceptual design of an effective fixed-film BNR biofilter system for the treatment of the influent simulated aquaculture wastewater was proposed based on the findings of the study.
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Kunjikutty, Sobhalatha Panangattu. "Floodplain filtration for treating municipal wastewaters". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100641.
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The effectiveness of a cheap, low-tech, environmentally and technically favorable treatment of secondary treated municipal wastewater by contaminant removal through a floodplain-soil filter was evaluated using floodplain-simulating field lysimeters, packed with a sandy soil in 2002 and sand in 2003 and 2004. Secondary treated wastewaters from Vaudreuil (2002 and 2003) and Pincourt (2004) Wastewater Treatment Plants were used as influent. This was applied at rates of 0.06, 0.19, and 0.31 m3 m-2 d -1 to vegetated lysimeters, and at a rate of 0.19 m3 m-2 d-1 to bare-soil lysimeters.Removal of NH4+-N, NO3--N, and COD from the influent was studied in all three years. Irrespective of flow rate or year, the system removed 62~84%, 96~99%, and 6~67% of TKN, NH4+-N, and COD, respectively, from the influent. Under 0.19 m3 m-2 d-1 flow rate, vegetated systems removed slightly more of these constituents from the influent, than did bare-soil lysimeters. Organic degradation mainly occurred in the top 0.1 m soil depth. Degradation of organic and inorganic influent nitrogen increased NO3--N levels in the effluent. Only minimal increases in soil-N levels and N2O emissions occurred with increasing application rates. The nitrogen mass balance accounted for 85∼98% (2003) and 67∼96% (2004) of input nitrogen (through leaching, soil retention, and N2O emissions), the remaining portion being attributable to vegetative effects and volatilization of non-N2O nitrogenous gases. The under established vegetation on the lysimeters reduced nitrogen leaching through soil, being 6% (2003) and 60% (2004) more effective than bare soil.
Effluent water quality improved with decreasing levels of heavy metals. Compared to influent levels, in vegetated lysimeters, under all flow rates, mean effluent As, Cd, Cu, Ni, Pb, and Zn levels had dropped by 58%, 9%, 3%, 37%, 63%, and 52% in 2003, and by 20%, 63%, 5%, 23%, 18%, 57%, and 79% for As, Cd, Cr, Cu, Ni, Pb, and Zn, in 2004. In both years, similar decreases in heavy metal levels occurred in the bare soil lysimeters. Across all flow rates and influent concentrations, soil heavy metal levels increased. In 2004, even low heavy metal content influent further increased (6∼179%) their accumulation in soil. As inputs of heavy metals to the soil increased with the increase in application rates, their associated times to reach maximum permissible limits also decreased.
LEACHN simulation of NO3--N in leachate arising from wastewater application, showed lowered levels with increasing flow rates, due to enhanced denitrification in the resulting anoxic upper soil zones. The simulation under continuous wastewater application at different range of nitrogen concentrations (low, medium, high) showed an increase of NO 3--N levels in the leachate with increasing N-levels. For all flow rates, and under tropical or humid conditions, the effluent NO 3--N levels remained below permissible limits for the low-N content wastewater applications. Intermittent applications, under all wastewater N-contents and flow rates, reduced NO3--N levels in the leachate by 51∼89% compared to continuous wastewater application, and permissible limits were not exceeded. Hence, wastewater with high levels of nitrogenous compounds, as occurs in most developing countries, could be treated by land under an intermittent application pattern, allowing a considerable reduction in nitrate pollution.
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Morgan, Pamela B. "Study of population dynamics in a biological phosphorouos removal wastewater treatment system". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-08182009-040452/.
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鍾偉聰 i Wai-chung Denis Chung. "Comparison of performance of thermophilic and mesophilic UASB reactorstreating protein-rich wastewater". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31215221.
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徐浩光 i Ho-kwong Chui. "Effect of substrate on the performance an sludge characteristics of UASB reactors". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31233533.
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The Best PhD Thesis in the Faculties of Dentistry, Engineering, Medicine and Science (University of Hong Kong), Li Ka Shing Prize,1993-1995published_or_final_version
Civil and Structural Engineering
Doctoral
Doctor of Philosophy
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Wong, Yee Keung. "Feasibility of using Chlorella vulgaris for the production of algal lipids, for advancement towards a potential application in the manufacture of commodity chemicals and the treatment of wastewater". HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/254.
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Driven by the increase in industrialization and population, the global demand of energy and material products is steadily growing. Microalgae have come into prominence in the past several decades due to their ability to utilize solar energy to fix atmospheric carbon dioxide, and produce biomass and lipids at productivities much higher than those possible with terrestrial biomass. The main objective of this research is to maximize the biomass and lipid production of Chlorella vulgaris by varying different external conditions so as to achieve the ideal feedstock for the production of commodity chemicals and implement wastewater treatment. The effects of various culture medium compositions on Chlorella vulgaris growth and lipid production were investigated using batch culture. Thirteen culture media: Modified Chu’s No. 10, Bold basal, BG-11, Modified BG-11, N-8, M-8, RM, Modified Spirulina, F-si, Fogg’s Nitrogen free, Fog, F/2, and Johnson medium were compared in terms of optical density, biomass production, specific growth rate and lipid production. Following a 10-day culture in a temperature controlled environment, Bold basal medium was found to have the highest average biomass productivity of 48.056 ± 2.097 mg L -1 day -1 , with overall specific growth rate of (d -1 ): 0.211 ± 0.003 and lipid productivity of 9.295 mg L -1 day -1 among the selected media. This is a basis for the optimization of different cultivating medium to enhance algal lipid production. In order to maximize the quality and quantity of the algal biomass and lipid content in Chlorella vulgaris, different strategies were used using different ratios of nitrogen and phosphorus source in the modified Bold basal medium (BBM). In the 12-day batch culture period, the highest biomass productivity obtained was 72.083 mg L -1 day -1 under Bold basal medium with Nitrogem control Phosphorus limited conditions. The highest lipid content, lipid concentration and lipid productivity obtained were 53.202%, 287.291 mg/L and 23.449 mg L -1 day -1 respectively, under Bold basal medium with Nitrogen Control Phosphorus Deprivation conditions. Nitrogen starvation was found to be the critical factor affecting the biomass production and lipid accumulation while the starvation of phosphorus induced a higher total lipid content and affected the lipid composition of Chlorella vulgaris cultures. Recently, as the demand for pure microalgae strains for the production of algal lipid as a feedstock of renewable energy has been increasing, the designation of an effective photobioreactor (PBR) for mass cultivation is essential to assure stability in the amount of feedstock. Various PBRs design such as bubbling, air-lift, porous air-lift was compared. In general, the bubbling design is a better PBR designs than the others, having the highest biomass concentration of 0.78 g/L during the culture time. Besides, it was observed that the 35 cm draft tube of the porous air-lift PBR had shorter mixing time (24.5 seconds) and higher biomass concentration (0.518 g/L) than the 50 cm air- lift design. The bubbling PBR with the highest gas flowrate of 2.7 L/min produced the highest biomass production of 0.74 g/L within the cultivation time. The information is shown to be a useful guide for determining the optimal condition of the PBRs. Light wavelengths and intensities were determinant factors in affecting the growth and lipid content of autotrophic organisms such as C. vulgaris. The experiment investigated the effect of algal lipid production by using LEDs (Light Emitting Diodes) with different wavelengths. C. vulgaris was grown in the effluent for 10 days under the photoperiod of 18:6 h Light/Dark cycles with different visible light sources (cool white, blue and red) and intensities (50 μmol m -2 s -1 ) at 25°C. The overall maximum dry biomass of 1353.33 mg/L was observed at 50 μmol m -2 s -1 cool white light during 10th culture day, with the highest overall productivity of dry biomass production (117.23 mg/L d -1 ) within cultivation time. The highest lipid content (34.06 %) was obtained with the blue color due to light efficiency and deep penetration to the photosynthetic pigments (chlorophyll) in C. vulgaris. However, the highest lipid productivity was observed in cool white light of 318.63 mg/L during the 10th culture day. The effect of light intensity toward the lipid productivity was further investigated by increasing the light intensity of cool white light. The highest lipid productivity was observed at 110 μmol m -2 s -1 in a light intensity of 658.99 mg/L during the 10th culture day. In high irradiance (110 μmol m -2 s -1 ), the proportion of poly unsaturated fatty acid (C18:1 and C18:2) contributed most of the fatty acid methyl ester (FAME) content in the collected sample, irrespective of all treatments. The next study optimized the harvesting rate of algae by using an electro- coagulation-flotation (ECF) harvester, which combines the electrochemical reaction in the electrodes and the dispersion of hydrogen gas to allow floatation of microalgae cell for surface harvesting. The response surface methodology model (RSM) was employed to optimize different ECF parameters: electrode plate material, electrode plate number, charge of electrode, electrolyte concentration and pH of the solution. The model revealed that aluminum was the best electrode material for the ECF process. It was also found that a three electrode plates setup with one anode and two cathodes had the best performance for harvesting. Additionally, sodium chloride (NaCl) at 8 g/L in harvesting medium could increase the flocculant concentration and reduce electric power consumption. Also, having the culture medium at pH 4 also had a significant effect on improving the flocculant production. Combining these optimal conditions, the highest flocculant concentration reached 2966 mg/L in 60 mins; a 79.8% increase in flocculant concentration, based on the tested conditions. The results of this study show the significance of different parameters affecting the coagulation and flocculation of C. vulgaris and provide a reference for the design of a large-scaled harvester for microalgae harvesting in the further study. To conclude, this research comprises a study on the use of indigenous algae for the production of algal lipid, which is used to produce commodity chemicals. Details on the use of nutrient sources, the techniques of cultivation and the optimization of cell harvesting were included so as to remove nutrients from effluents to minimize the occurrence of eutrophication in harbor, thereby providing economic advantages. Thus, the optimization of these processes is very adequate and offers significant advantages for the wastewater treatment. The developing of algal cell biotechnology is necessary to further enhance algal lipid production in an attempt to apply it commercially.
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Mpentshu, Yolanda Phelisa. "Biosurfactant producing biofilms for the enhancement of nitrification and subsequent aerobic denitrification". Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2842.
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Thesis (Master of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2018.Wastewater treatment methods have always gravitated towards the use of biological methods for the treatment of domestic grey water. This has been proven to offer a series of advantages such as the reduction of pollution attributed to the use of synthetic chemicals; therefore, this decreases the requirement of further costly post primary treatment methods. Although such biological methods have been used for decades, their efficiency and sustainability has always been challenged by inhibitory toxicants which renders the systems redundant when these toxins are prevalent in high concentrations, culminating in the deactivation of biomass which facilitates the treatment. In most instances, this biomass is anaerobic sludge. Hence, the proposal to utilize biofilms which are ubiquitous and selfsustaining in nature. The use of engineered biofilms in wastewater treatment and their behaviour has been studied extensively, with current research studies focusing on reducing plant footprint, energy intensity and minimal usage of supplementary synthetic chemicals. An example of such processes include traditional nitrification and denitrification systems, which are currently developed as simultaneous nitrification and aerobic denitrification systems, i.e. in a single stage system, from the historical two stage systems. However, there is limited literature on biofilm robustness against a potpourri of toxicants commonly found in wastewater; particularly for total nitrogen removal systems such as simultaneous nitrification and denitrification (SND). This study was undertaken (aim) to assess the ability of biosurfactant producing biofilms in the removal of total nitrogen in the presence of toxicants, i.e. heavy metals and phenol, as biosurfactants have been proven to facilitate better mass transfer for pollutant mitigation. Unlike in conventional studies, the assessment of biosurfactant producers in total nitrogen removal was assessed in both planktonic and biofilm state. Since biofilms are known to have increased tolerance to toxic environmental conditions, they were developed thus engineered using microorganisms isolated from various sources, mainly waste material including wastewater as suggested in literature reviewed, to harness microorganisms’ possessing specified traits that can be developed when organisms are growing under strenuous environments whereby they are tolerant to toxic compounds. The assessment of these engineered biofilms involved the development from individual microorganisms to form biofilms in 1L batch reactors where the isolated microorganisms were grown in basal media containing immobilisation surfaces. The assessment of the total nitrogen efficiency was conducted using Erlenmeyer flasks (500mL) in a shaker incubator, with the biofilm TN removal efficiency being assessed in batch systems to ascertain simultaneous nitrification and denitrification rates even in the presence of heavy metals (Cu2+, Zn2+) and C6H5OH. Ambient temperature and dissolved oxygen conditions were kept constant throughout the duration of biofilm development with microorganisms (initially n = 20) being isolated for the initiation of biosurfactant studies which included screening. Results indicated that the engineered biofilms, constituted by biosurfactant producing organisms (n = 9), were consisiting of bacteria (97.19%), Protozoa (2.81%) and Archaea (0.1%) as identified using metagenomics methods. Some of the biosurfactant produced had the following functional group characteristics as determined by FTIR: -CH3-CH2, deformed NH, -CH3 amide bond, C-O, C=O, O-C-O of carboxylic acids, and C-O-C of polysaccharides. Other selected microorganisms (n = 5) tolerated maximum concentrations of the selected toxicants (Cu2+, Zn2+ and C6H5OH) of 2400 mg/L, 1800 mg/L and 850 mg/L, respectively. Enzyme analysis of the total nitrogen removal experiments indicated a higher nitrogen removal rate to be the Alcanigene sp. at 180 mg/L/h.
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Maeng, Sung Kyu. "Effect of a silver-bearing photoprocessing wastewater and silver compounds on biological treatment processes". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19024.
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Neba, Alphonsus. "The Rhodes BioSURE process and the use of sustainability indicators in the development of biological mine water treatment". Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1004043.
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Polluted waters, arising from extensive past and ongoing mining operations in South Africa, pose serious environmental threats to the limited fresh water resource. The long time periods, of decades to centuries, over which decanting mine waters may be expected to flow raises additional concerns about the sustainability of these resources. Responses to the problem have thus increasingly been directed towards the long-term sustainability of mine water treatment technologies (MWTT) as a critical indicator in both their research and development, and application. Bioprocess treatments have been considered in this regard and, among these, the Rhodes BioSURE Process has been investigated in preliminary studies using complex organic carbon wastes as the carbon source and electron donor for the central sulphate reduction unit operation. Although both the mining industry and the related statutory/regulatory authority in South Africa share public commitment to sustainability in the treatment of mine waters, no systematic mechanism has emerged to enable the application of sustainability thinking as a guiding principle in the selection and application of MWTTs, nor in the research and development undertaking. This study undertook the development of a Sustainability Indicator Framework in order to provide a systematic basis for the incorporation of sustainability objectives in MWTT bioprocess development, and specifically to use this framework as an input to the investigation of the scaleup development of the Rhodes BioSURE Process. In the development of the MWTT Sustainability Indicator Framework, an initial survey of industry thinking in this area was undertaken and, based on these outcomes, a detailed questionnaire methodology was developed in order to identify and quantify critical sustainability indicators. These included analysis of environmental, economic, social and technical indicators used in sustainability accounting practice in the industry. Statutory/regulatory sustainability targets in the same categories were derived from State of the Environment Reports (SoER) from Provincial authorities where mining is undertaken in South Africa. A synthesis of industry and SoER values was derived from weighted averages and the Sustainability Indicator Framework based on these outcomes. A Conceptual Decision-Support System, to guide the selection and development of MWTTs, was proposed and also based on these results. In the development of the Rhodes BioSURE Process the use of primary sludge (PS) had been investigated as a potential complex carbon and electron donor source. In this regard the utility operator, and sewage treatment process infrastructure, was identified as potentially meeting aspects of the sustainability objectives identified for MWTT application development. Both the Sustainability Indicator Framework and the Conceptual Decision-Support System provided inputs in the formulation of the experimental programme relating to the scale-up development of the Rhodes BioSURE Process. Based on these outcomes, a series of single- and multi-stage reactor configuration, optimisation and enzymology studies were undertaken at bench-, pilot- and technical-scale operations. These units were operated at hydraulic retention times (HRT) ranging between 22 to 72 hours and at chemical oxygen demand to sulphate ratios (COD:SO[subscript 4]) ranging between 1:1 to 2:1. Studies undertaken in fed-batch, bench-scale reactors confirmed the preliminary feasibility of using established sewage treatment infrastructure as a replacement for novel reactor configurations that had been used in the initial studies. The results further indicated that the hydrolysis of PS occurred at different rates under biosulphidogenic conditions in the different reactor configurations investigated. Scale-up of these findings in multi-stage pilot- (7.4m[superscript 3]) and technical-scale plants (680m[superscript 3]) showed comparable performances between the unit operations in terms of SO[subscript 4] and COD removal. These results indicated no apparent advantages in the uncoupling of hydrolysis and sulphate reduction in separate unit operations as had been suggested in previous studies. Scale-down/scale-up studies were undertaken in a continuously fed single-stage reactor configuration and showed that the process could be effectively operated in this way. Previous proposals that chemical and biological gradients established in the sludge bed of the Recycling Sludge Bed Reactor (RSBR) exercised an influence on the rates of substrate hydrolysis were investigated and the relative activity of α- and β-glucosidase and protease enzymes was measured. Results provided additional support for this hypothesis and it was shown that enzyme assay may also provide a useful tool in process development and monitoring studies. While sulphide recovery, following the sulphate reduction step in the BioSURE Process, was not investigated as a component of this study, the treatment of final effluent or waste spills was identified as an important sustainability requirement given the toxicity of sulphide to human and ecosystem environments. A conventional trickle filter reactor system was evaluated for this purpose and showed close to 100% oxidation to sulphate in a short contact time operating regime. Although residual COD removal was low at ~20% of influent, it is considered that high rate recycle biofilter operation could achieve the COD discharge standard of 75 mg/l. The results of the above studies provided inputs into the design, construction and commissioning of the first full-scale commercial application of the Rhodes BioSURE Process for mine wastewater treatment using sewage sludge as the carbon and electron donor source. An adjacent mine and sewage works have been linked by pipeline and an operational capacity of 10 Ml/day water treated has been established with sulphate reduced from ~1300mg/l to <200mg/l. These developments constitute a novel contribution in the mine waste water treatment field.
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Hart, Vincent S. "An examination of biological phosphorus removal using bacterial counting and poly-β-hydroxybutyrate analysis in batch and continuous flow systems". Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/40652.
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The objective of this study was to examine excess biological phosphorus removing bacterial populations and their substrate utilization mechanisms. This study was a smaller part of a overall study of temperature effects upon excess biological phosphorus removal.
Bacterial populations in both a continuous flow UCT (University of Cape Town) system and batch reactors were examined by direct counting using a well known staining procedure (Neisser staining), and a microscopic counting method developed by Cech and Hartman (1993). Substrate utilization was examined using PHB (Poly-β -Hydroxybutyrate - an internal substrate storage product) analysis by gas chromatography to supplement COD and acetate measurements.
The results showed that Poly-P bacterial counts were significantly greater at a 5 day sludge age compared to a 10 day sludge age. It was noted from microscopic observations that the size of the poly-phosphate granules in the bacteria seemed to be a better indicator of system performance than the actual counts. It also was observed that the 'G' bacteria first described by Cech and Hartman (1993) were abundant at the 10 day sludge age but completely absent at the 5 day sludge age.
PHB storage occurred in both the anaerobic zone and the first aerobic tank, and PHB utilization was seen in the subsequent aerobic tanks of the UCT system. The formation of PHB in the first aerobic reactor when no substrate was available supports the Mino (1987) model for excess biological phosphorus removal.
In batch studies, substrate storage release were demonstrated in the aerobic zone. This explained why when acetate was present in the aerobic zone net phosphorus uptake didn't occur until all the acetate was utilized.
When the temperature was lowered in the UCT system nitrification ceased. This resulted in soluble COD breakthrough into the aerobic zone, which stimulated filamentous growth, and eventually caused a lack of PHB formation. All of these factors contributed to a loss of excess biological phosphorus removal at the low temperature.Master of Science
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Boshoff, Genevieve Ann. "Development of integrated biological processing for the biodesalination of sulphate- and metal-rich wastewaters". Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1003958.
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The substantial pollution threat to the South African environment from acid mine drainage (AMD) effluents has been well documented. Due to the juvenile nature of acidity in these flows, any remediation strategies implemented will need to function effectively and at low cost for long periods of time. The widespread use of sulphate reducing biological systems for the treatment of such effluents, and in particular large volume flows, has been limited. The supply of inexpensive electron donor and carbon sources, as well as appropriate reactor designs capable of handling large volume flows, have been identified as among the principal factors limiting development of this technology. The broad aim of the research programme reported here was to undertake an evaluation of the feasibility of an algal-bacterial integrated ponding system for the treatment of AMD, and the waste stabilisation pond (WSP) as an appropriate reactor design for this application. The study attempted to demonstrate the feasibility of individual unit operations in a proposed process train using complex organic carbon serving as the electron donor source for the sulphate reducing bacteria (SRB). Studies were undertaken as laboratory and pilot-scale investigations. Tannery effluent was shown to be a functional carbon source for biological sulphate reduction, with effective removal of sulphate and organics being recorded. In turn, the use of biological sulphate reduction for the treatment of tannery effluent was demonstrated. Algal biomass was shown in laboratory studies to function as an effective carbon source for biological sulphate reduction. It is known that micro-algae produce large quantities of photosynthate which is released to the growth medium under conditions of physiological stress. The potential for the use of photosynthate production in high rate algal ponding systems and its manipulation and use as a sustainable carbon source for sulphate reduction was investigated. Growth of a mixed culture of Dunaliella under conditions of light, temperature and salinity stress demonstrated production of large quantities of organic carbon. However, growth was inhibited at high temperatures. An elevation of salinity levels led to a decrease in growth of Dunaliella, but to increased organic carbon production. Spirulina spp., on the other hand, grew well at higher temperatures but showed the highest organic carbon production, and release to the medium, under low light conditions. These results led to a proposed process for the integration of algal ponding into an integrated system for the treatment of AMD. The algal biomass may be fed into the anaerobic digester as a carbon source, or it may be passed into a High Rate Algal Pond (HRAP) where it is stressed to enhance the organic carbon content. This can then be fed into the anaerobic digester as a carbon source. The impact of high levels of sulphide in the water feeding to the algal growth compartment was investigated. Spirulina spp. isolated from a tannery waste stabilisation pond was shown to be a sulphidophilic strain of cyanobacterium, capable of being adapted to high concentrations of sulphide. Dunaliella salina on the other hand was less tolerant. These results demonstrated the practical use of algal biomass providing an oxygen-rich cap for odour control on the surface of the facultative pond as well for the secondary treatment of sulphide-rich overflow to the High Rate Algal Pond. The ability of micro-algae to elevate the pH of their surrounding environment was evaluated as a functional precipitant and neutralisation reagent for acidic metal containing wastewater. Spirulina spp. was shown to perform effectively. D. salina was less functional in this environment. Anacystis spp. was effective in elevating the pH of a defined medium as well as a zinc-rich effluent. These results indicated the practicality of a neutralising function for algal ponds in the treatment of AMD. Metal removal in the system was found to be a combined function of sulphide precipitation, removal by binding to micro-algal biomass and extracellular polymeric substances. The feasibility of waste stabilisation ponding technology use for the treatment of large volume AMD effluents was provisionally demonstrated. It was shown that complex carbon sources would be used as efficient electron donors for sulphate reduction. The integration of algal ponding into the system provides for the generation of a sustainable carbon source, odour control with the recycling of oxygen-rich water onto the top of the facultative pond, secondary treatment of the anaerobic digester overflow, and the neutralisation of the incoming acidic effluents and removal of heavy metals. Integration of the individual unit operations, the feasibility of which has been provisionally demonstrated in this study, into a continuous process train is being investigated in follow-upstudies.
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Smuts, Lizl. "Investigation into the biological removal of sulphate from ethanol distillery wastewater using sulphate-reducing prokaryotes". Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1004000.
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Ethanol production wastewater is known to be toxic, and is not easily biodegradable. It also consists of a variety of coloured components adding to the complex composition of this wastewater. Disposal of this wastewater into water courses is not recommended and yet is performed all over the world. Investigation of this wastewater found that there was a high concentration of sulphate which, in the presence of sulphate-reducing prokaryotes can cause sulphide corrosion of cement. The concentration of sulphate in the wastewater was approximately 2770 mg/L. It was also found that the wastewater pH was very low and discharge of the wastewater into the wastewater treatment works caused a negative impact on the overall quality of the final wastewater discharged to sea. It was found using FISH techniques that there were no sulphate-reducing prokaryotes present in the wastewaters but that a sulphate-reducing population existed on the sewer wall. An anaerobic contact process was designed to treat this wastewater targeting sulphate reduction to sulphide, to be converted into elemental sulphur and to increase the wastewater pH. The process did not achieve this aim and only approximately 20-30 % reduction in sulphate from the wastewater was achieved with little to no change in the pH. A 95 % reduction in sulphate concentration was needed in order to reach acceptable discharge limits. Sulphate reduction could not be carried out, even under ideal laboratory conditions. It was found that the barrier causing the digester failure was the high concentration of phenols present in the wastewater (3.3 g/L) together with the production of high concentrations of volatile fatty acids (on average 13 g acetic/L). These two components are known to cause digester failure, especially phenols, and phenols are usually only degraded by fungal species. It was concluded that the wastewater itself was not amenable to this method of biological treatment.
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Silva, Gustavo Henrique Ribeiro da. "Reator compartimentado anaerobio/aerobio, tratando esgoto sanitario : desempenho e operação". [s.n.], 2001. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258316.
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Orientador: Edson Aparecido Abdul NourDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil
Made available in DSpace on 2018-08-03T00:31:08Z (GMT). No. of bitstreams: 1 Silva_GustavoHenriqueRibeiroda_M.pdf: 10901410 bytes, checksum: 214e9f14f9626400264bad3cf93fade5 (MD5) Previous issue date: 2001
Resumo: No presente trabalho de pesquisa foi estudada uma alternativa de união de processos anaeróbios e aeróbios sob a forma de um reator compartimentado anaeróbio/aeróbio, no tratamento de esgoto sanitário. O reator era composto por quatro câmaras seqüenciais, sendo as três primeiras anaeróbias e a última aeróbia, totalizando um volume aproximado de 2,5 m3. O Iodo gerado pelo reator foi separado em um decantador laminar e recirculado à quarta câmara. O reator, localizado em uma E.T.E. da cidade de Limeira, SP, foi operado durante um período de 444 dias, divido em cinco fases, com tempo de detenção hidráulica (TDH) total variando de 7 a 16 horas, alimentado com esgoto sanitário que havia recebido tratamento preliminar. As cinco fases de operação corresponderam a 10, 16, 12, 8 e 7 horas de TDH. Os valores de pH ao longo de todas as câmaras e decantador, variaram entre 5,7 e 8,3 e o valor médio foi de 6,8, não sendo necessário correção e pH durante o período de estudo. Os melhores valores de remoção de 0805 foram obtidos na Fase 4 (TDH=8 horas), 56,9 a 95,7%. Contudo o teste estatístico de comparação de médias de duas amostras, verificou não. haver diferença significativa entre as fases, exceto Fase 2, ao nível de P=O,05. O desempenho do reator quanto a remoção de DQOtotal e SST foi semelhante ao obtido para 0805, com valores de 31,4 a 95,6 e 21,0 a 97,3%, respectivamente, o mesmo ocorrendo para o teste estatístico realizado. Os valores encontrados para oxigênio dissolvido no interior da câmara 4 (aeróbia) foram satisfatórios na maior parte do tempo, de acordo com os valores citados na literatura, alcançando valor máximo de 4,70 e mínimo de O mg 02.L-1. A presença do decantador laminar foi importante na remoção de sólidos provenientes do reator. Após o 1070 dia de operação, o Iodo de recirculação apresentou uma sedimentabilidade de boa a ótima. A configuração do sistema em estudo, promove adequado tratamento do efluente aplicado aliado a uma produção de Iodo aeróbio de fácil gerenciamento
Abstract: The present research aimed to study an alternative route for union of aerobic and anaerobic processes, through the use of a baffled reactor, treating sanitary wastewater. The reactor is composed of four sequential chambers, being the first tree anaerobic chambers and the last one aerobic, composing a total volume of approximately 2.5 m3. The sludge generated in the reactor is separated in a laminar sedimentation tank and recycled into the forth chamber. The reactor - placed in a wastewater treating plan of Limeira city, S. P., 8razil -operated in a period of 444 days. This period was divided in five phases, with hydraulic detention times (HOT) varying from 7 to 16 hours. The reactor was fed with sanitary wastewater which had already suffered a preliminary treatment. The five phases of operation corresponded to 10, 16, 12,8 e 7 hours of HOT, respectively. The pH values in all chambers and in the sedimentation tank, varied between 5,7 e 8,3, with a mean value of 6,8; the correction of pH values was not necessary during all periods. The best value of 8005 removal was attained in the Phase 4 (HOT=8 hours), 56,9 to 95,7%. However, the statistic comparison of the means .of two samples showed that there was no significant difference between the phases, except in Phase 2, with P=0,05. The reactor performance, in relation to COOtotal removal and TSS, was similar to that obtained for the 8005, with values of 31,4 to 95,6 and 21,0 to 97,3%, respectively. The same occurred in the statistic test. In chamber 4, the oxygen dissolved values were satisfactory in most of the periods, reaching the maximum of 4,7 and of 0,0 mg 02.L-1. The laminar sedimentation tank was important for removal of solids produced in the sedimentation tank. After the 10ih operation day, the recycled sludge presented a sedimentation capability classified between good and very good. Thus, It is possible to affirm that the baffled reactor configuration of the present work promotes an useful effluent treatment, employed to the production of an aerobic sludge with easy management
Mestrado
Saneamento e Ambiente
Mestre em Engenharia Civil
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Ginige, Pushpa. "Decontamination of biosolids for land application : metals bioleaching and process impacts on the nutrient value of biosolids". Thesis, Queensland University of Technology, 1998.
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Tam, Ka-man, i 譚家雯. "Autotrophic denitrification of synthetic wastewater in biological activated filter (BAF) reactors with sulfur media". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B3878922X.
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Ehlers, George A. C. "Integrated anaerobic/aerobic bioprocess environments and the biodegradation of complex hydrocarbon wastes". Thesis, Rhodes University, 2004. http://hdl.handle.net/10962/d1004071.
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An investigation of the biodegradation of complex hydrocarbon wastes, with emphasis on chlorinated aromatic compounds, in an anaerobic/aerobic bioprocess environment was made. A reactor configuration was developed consisting of linked anaerobic and aerobic reactors which served as the model for a proposed bioremediation strategy targeting subterranean soil/sediment/aquifer chlorinated phenol-contaminated environments. Here oxygen is frequently limited and sulphate is readily available, as occurs especially in marine sediment and intertidal habitats. In the anaerobic system the successful transformation and mobilization of the model contaminant, 2,4,6-trichlorophenol, was shown to rely on reductive dechlorination by a sulphate-reducing dependent dechlororespiring co-culture. This was followed in the aerobic system by degradation of the pollutant and its metabolites, 2,4-dichlorophenol, 4-chlorophenol and phenol, by immobilized white-rot fungi.The strategy was initially investigated separately in laboratory bench- and intermediate scale reactors whereafter reactors were linked to simulate the integrated biodegradation strategy. The application of the fungal reactor to treat an actual waste stream by degrading complex mixtures of hydrocarbons in a waste oil recycling effluent was also investigated. The mineralization of phenol and 2,4,6-TCP by immobilized fungal cultures was studied in pinewood chip and foam glass bead-packed trickling reactors. The reactors were operated in sequencing batch format. Removal efficiency increased over time and elevated influent phenol and TCP (800 and 85 mg.L⁻¹) concentrations were degraded by > 98 % in 24 – 30 h batch cycles. Comparable performance between the packing materials was shown. Uptake by the packing was negligible and stripping of compounds induced by aeration had a minimal effect on biodegradation efficiency. Reactor performances are discussed in relation to sequencing batch operation and nutrient requirements necessary to sustain fungal activity in inert vs. organic material packed systems. It was shown that a co-culture consisting of sulphate-reducing and dechlororespiring bacteria established in fed-batch and soil flasks, as well as pine chip-packed fluidized bed reactors. Results showed reductive dechlorination of 2,4,6-TCP to be in strict dependence on the activity of the sulphate-reducing population, sulphate and lactate concentrations. Transformation to 2,4-DCP, 4-CP and phenol was enhanced in sulphate deficient conditions. Dechlororespiring activity was found to be dependent on the fermentative activity of sulphate-reducing bacteria, and the culture was also shown to mobilize and dechlorinate TCP in soils contaminated with the pollutant. Linking the systems achieved degradation of the compound by > 99 % through fungal mineralization of metabolites produced in the dechlororespiring stage of the system. pH correction to the anaerobic reactor was found to be necessary since acidic effluent from the fungal reactor inhibited sulphate reduction and dechlorination. The fungal reactor system was evaluated at intermediate-scale using a complex waste oil recycling effluent. Substantial COD reduction (> 96 % in 48 h batch cycles) and removal of specific effluent hydrocarbon components was shown in diluted, undiluted (COD > 37 g.L⁻¹) and 2,4,6-TCP-spiked effluents. Industrial application of the fungal reactor was evaluated in a 14 m³ pilot plant operated on-site at a waste oil processing plant.
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Liang, Dawei, i 梁大為. "Anaerobic degradation of toxic and refractory aromatics". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3865023X.
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Pardieck, Daniel L. "Biodegradation of phenols in aquatic culture by soil-derived microorganisms, with reference to their fate in the subsurface". Diss., The University of Arizona, 1988. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1988_226_sip1_w.pdf&type=application/pdf.
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Chen, Tong, i 陳彤. "Anaerobic treatment of benzoate- and phenol- containing wastewaters". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31212918.
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Shetty, Ameesha R. "Metal anion removal from wastewater using chitosan in a polymer enhanced diafiltration system". Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-050406-115241/.
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Jackson-Moss, Clive Alan. "An investigation into the use of anaerobic digestion for the treatment of tannery wastewaters". Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1004120.
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The anaerobic digestion of tannery wastewaters was investigated with a view to using this form of treatment in the tanning industry. As these wastewaters are extremely complex and contain high concentrations of both inorganic and organic compounds, the effect of these individual compounds on the anaerobic digestion process was investigated in detail, in order to ascertain the fate of these compounds during the digestion process. The experiments comprising the initial toxicity study were carried out as adaptation experiments using a synthetic wastewater. It was found that the heavy metals such as chrome, aluminium and iron precipitated and accumulated in the sludge bed of the digesters . The soluble ions such as sodium and chloride were not retained and passed through the digesters. Approximately 20 % of the calcium ions were removed through precipitation, with the remainder being present in the digester effluent . Under the anaerobic conditions, ammonification of the organic nitrogen occurred, and influent sulphates were reduced to sulphides . These sulphides were present as either H2S, HS or insoluble sulphides. As these compounds under investigation on caused no inhibition of the anaerobic digestion process at the concentrations found in tannery wastewaters, the anaerobic treatment of these wastewaters appeared to be possible, provided the bacteria were given sufficient time to adapt to the potentially toxic compounds. However, despite the findings of the synthetic study, the successful anaerobic digestion of the tannery effluents could not be achieved. Although the use of acid was found to be essential in order to control the digester pH in the optimum range, the metabolism of the methanogenic bacteria was inhibited by the presence or absence of unknown compounds. Neither the addition of essential trace nutrients, nor the prevention of the competition between the methanogens and the sulphate-reducing bacteria were able to reverse this inhibition. As tannery effluents contain very low concentrations of phosphorous, it is possible that the methanogens were inhibited by a lack of phosphorous, which is essential during methanogenesis. In contrast to the results obtained from the effluent experiments, the anaerobic digestion of tannery sludge was found to be possible. Of the organic solids present in the sludge, 60 % were degraded and converted into biogas, which had a methane content greater than 70 %. The degradation of the organic solids ensured that COD and PV reductions of greater than 90 % were achieved, and the fate of the compounds in the digesters were in agreement with the findings of the v synthetic study. Efforts to improve the efficiency of the digestion process through the addition of trace nutrients and the use of a two-stage process were only successful in bringing about a minor improvement in digester performance. The overall results of this investigation show, therefore, that although the anaerobic treatment of the tannery effluent was not achieved, the successful anaerobic digestion of tannery sludge is possible at low loading rates. As many difficulties still need to be solved, a great deal of further research is necessary if anaerobic digestion is to be used on an industrial scale for the treatment and disposal of tannery wastewaters.