Rozprawy doktorskie: „Nitrogen removal”

1

Ahlin, Björn T. I. "Nitrogen Removal in a Vacuum Tank Degasser : An Investigation on the Nitrogen Removal Performance". Thesis, KTH, Materialvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-256066.

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The impending change of processes at SSAB Oxelösund due to the HYBRIT project, where the blast furnace and LD converter are to be replaced with an EAF will have a significant impact on the manufacturing of steel in Oxelösund. One issue that will arise is the nitrogen content in the steel. Sources claim that the nitrogen content in steel from an EAF route is substantially larger, 60-70 ppm, than in steel from a blast furnace and LD converter route, which have a nitrogen content of around 25 ppm. Therefore, the nitrogen removal capabilities of SSAB Oxelösund’s vacuum tank degasser were to be examined. Industrial trials were performed where the amount of slag during vacuum treatment was lowered. The intention was that half the amount of slag removed prior to vacuum treatment and later completely slag free. This was performed in an attempt to increase the effective reaction area, where nitrogen removal occurs. Due to some practical problems with the steel mill, the industrial trial were unfortunately cut short. Consequently, only trials with half the amount of slag were performed and compared to existing process data for standard praxis. Also, nitrogen removal calculations based on the industrial data were performed. A parameter representing the overall reaction rate, which is dependent on effective reaction area was obtained, validated and subsequently applied to a future case scenario. The results indicate that the reduction in slag amount does have the desired effect, increasing the said area and increasing the rate of nitrogen removal. However, the sample size is not nearly sufficient enough to determine this definitively. The conclusions reached were that the facility does have the possibility to decrease the increased nitrogen content down to reasonable levels, around 20-30 ppm. Albeit, an increase in vacuum treatment time is probably required. Another conclusion was that surface active elements, such as oxygen and sulphur greatly reduce the nitrogen removal. Therefore, efforts should be taken to remove these elements prior to vacuum treatment. In addition, it was established that the effective reaction area is of great importance for a successful nitrogen removal. Therefore, actions to maximise this area should be taken. Finally, it was stated that further research is necessary in order to fully understand nitrogen contamination prevention- and removal techniques
Förändringar till följd av HYBRIT projektet kommer påverka SSAB Oxelösunds stålverk. Masugn och LD konverter skall ersättas med ljusbågsugns teknologi. Ett problem till följd av detta är kvävehalter i stålet. Enligt litteraturen är kvävehalterna betydligt högre i stål tappat från en ljusbågsugn. Med kvävehalter runt 60-70 ppm jämfört med stål tappat från en LD konverter som har kvävehalter kring 25 ppm. Därför krävdes en undersökning kring kvävereningpotentialen för SSAB Oxelösunds vakuum tank avgasare. Industriella experiment med minskad slaggmängd jämfört med standard praxis blev utförda. Detta utfördes med tanken att minskad slaggmängd skulle ge en större effektiv reaktionsarea. Intentionen var att utföra försök först med halverad slaggmängd följt av slaggfria försök. Dock, på grund av produktions praktiska problem vid verket blev försöken avbrutna. Som en följd av detta blev bara försök med halverad slaggmängd utförda och jämförda med processdata från standard praxis. Kvävereningsberäkningar på historisk processdata utfördes. En parameter som representerade genomsnittlig reaktionshastighet, vilken beror på den effektiva reaktionsarea blev erhållen, validerad och senare applicerad på ett hypotetiskt framtida scenario. Resultaten indikerar att minskad slaggmängd har en positiv inverkan på den effektiva reaktions arean och till följd av detta även en positiv inverkan på kväverening. Dock är för få försök utförda för att kunna fastställa detta. De slutsatser som dras är att vakuum anläggningen vid SSAB Oxelösund har möjligheten att, med förlängd vakuumbehandlingstid, rena de ökade kvävehalter till nivåer runt 20-30 ppm. Ytterligare slutsatser var att ytaktiva element, såsom syre och svavel, i stålet har en stor negativ påverkan för kväverening. Samt att den effektiva reaktionsarean är av stor betydelse för kväverening. Därför bör ansträngningar tas för att minska koncentrationen av ytaktiva element samt att försöka göra den effektiva reaktionsarean så stor som möjligt. Slutligen fastställdes det att ytterligare studier är nödvändiga för att öka kunskapen kring förebyggande tekniker och reningstekniker för kväveföroreningar i stål.

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Lingaraju, Bala P. "Removal of Nitrogen from Wastewater Using Microalgae". University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321888338.

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Samuelsson, Pär. "Control of Nitrogen Removal in Activated Sludge Processes". Doctoral thesis, Uppsala University, Department of Information Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5903.

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More stringent requirements on nitrogen removal from wastewater are the motivation for this thesis. In order to improve treatment results and enhance cost-efficient operation of wastewater treatment plants, model based control strategies are presented.

A Java based simulator for activated sludge processes (JASS) is presented. The graphical user interface, educational experiences and implemented control strategies are discussed.

Controlling the addition of an external carbon source is the next topic discussed. A simple model based feedforward controller is derived and evaluated in a simulation study. The controller attenuates process disturbances quickly. Further, two feedforward controllers for adjusting the aeration volume in activated sludge processes are derived. The aim of the volume control strategies was to efficiently dampen the impact of process disturbances without using an excessively high dissolved oxygen concentration. The simulation results are promising and show that the aeration volume may be a feasible control variable.

A linearisation method for static input non-linearities is presented. The method gives essentially the same result as the existing standard method, but possesses some implementational advantages. The method is used to linearise the non-linear oxygen transfer function of an activated sludge process in an application study.

Multivariable interactions in a process model describing nitrate removal in an activated sludge process are studied using the well known RGA method as well as a relatively novel tool based on Hankel norms. The results of the analysis are compared to conclusions drawn from common process knowledge and are used to design a multivariable control strategy. It was found that process disturbances may be rejected faster using multivariable control.

Finally, the operational costs of the denitrification process are investigated and visualised graphically. Cost optimal regions are found by a numerical grid search. Procedures for controlling the denitrification process in a cost-efficient way are described.

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Herrman, Kyle S. "Mechanisms controlling nitrogen removal in agricultural headwater streams". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1181667344.

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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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TOCCO, GIAIME. "Autotrophic Nitrogen Removal From High Ammonium Containing Wastewater". Doctoral thesis, Università degli Studi di Cagliari, 2019. http://hdl.handle.net/11584/260406.

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The present thesis is framed within a wider project, promoted by the University of Cagliari and the Italian National Research Council, which pursued as its general objective the development of a novel integrated system for the biological combined anaerobic production of H2 and CH4 from the organic fraction of municipal solid waste (OFMSW), the valorization of solid residues by aerobic bio-oxidation (composting) and the biological treatment of ammonium-rich liquid by products by two-stage partial nitritation (PN)/anaerobic ammonium oxidation (anammox) process. According to the project plan, a biological combined anaerobic production of H2 and CH4 from the OFMSW took place in two different bioreactors, in a double-step configuration. The effluent from the second reactor underwent a liquid/solid separation. The assessment of feasibility of the treatment of the liquid fraction by means of two-stage autotrophic nitrogen removal was the research question that tracked the main investigation line of the work described in the present thesis. The application of the coupled PN/anammox process, also referred to as fully autotrophic nitrogen removal, would allow to increase the sustainability of the entire OFMSW treatment chain, since the need for carbon addition (and concomitant increased sludge production) is omitted, oxygen consumption (i.e., energy requirement) is reduced, and the emission of nitrous oxide (a significant factor in the greenhouse gas footprint of the total water chain) can be cut significantly. To date, few researches focused on the application of partial nitritation/anammox process for the treatment of the liquid fraction originated by the anaerobic digestion of organic substrates such as OFMSW. Moreover, the two-stage anaerobic digestion of such substrates is a relatively novel technology which has not deeply investigated yet in terms of its potential environmental impact, and few studies focused on characterization and management of the liquid residues. To the best of our knowledge, no previous study was performed concerning the application of the two-stage PN/anammox process for the treatment of the anaerobic supernatant of a two-stage anaerobic digestion of organic fraction of municipal solid waste and food waste.

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Stocks, Justine L. "Enhancement of Two Passive Decentralized Biological Nitrogen Removal Systems". Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/7093.

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This research evaluates two different Biological Nitrogen Removal (BNR) systems for enhanced nitrogen removal in decentralized wastewater treatment. The first study evaluated the performance of Hybrid Adsorption and Biological Treatment Systems (HABiTS) at the pilot scale with and without stage 1 effluent recirculation. HABiTS is a system developed at the bench scale in our laboratory and was designed for enhanced BNR under transient loading conditions. It consists of two stages; an ion exchange (IX) onto clinoptilolite media coupled with biological nitrification in the aerobic nitrification stage 1 and a Tire-Sulfur Adsorption Denitrification (T-SHAD) system in the anoxic denitrification stage 2. The T-SHAD process incorporates NO3- adsorption onto tire chips and Sulfur Oxidizing Denitrification (SOD) using elemental sulfur as the electron donor for NO3- reduction. Previous bench scale studies evaluated HABiTS performance under transient loadings and found significantly higher removal of nitrogen with the incorporation of adsorptive media in stage 1 and 2 compared with controls (80% compared to 73%) under transient loading conditions. In this study, we hypothesize that a HABiTS system with effluent recirculation in nitrification stage 1 may enhance nitrogen removal performance compared to that without recirculation. The following were the expected advantages of Stage 1 effluent recirculation for enhanced nitrogen removal: 1) Pre-denitrification driven by the mixture of nitrified effluent from stage 1 with high concentrations of biochemical oxygen demand (BOD) septic tank effluent. 2) Moisture maintenance in stage 1 for enhanced biofilm growth. 3) Increased mass transfer of substrates to the biofilm in stage 1. 4) Decreased ratio of BOD to Total Kjeldahl Nitrogen (TKN) in the influent of stage 1. Two side-by-side systems were run with the same media composition and fed by the same septic tank. One had a nitrification stage 1 effluent recirculation component (R-system), which operated at a 7:1 stage 1 effluent recirculation ratio for the first 49 days of the study and at 3:1 beginning on day 50 and one was operated under forward flow only conditions (FF-system). The R system removed a higher percentage of TIN (35.4%) in nitrification stage 1 compared to FF (28.8%) and had an overall TIN removal efficiency of 88.8% compared to 54.6% in FF system. As complete denitrification was observed in stage 2 throughout the study, overall removal was dependent on nitrification efficiency, and R-1 had a significantly higher NH4+ removal (87%) compared to FF-1 (70%). Alkalinity concentrations remained constant from stage 1 to stage 2, indicating that some heterotrophic denitrification was occurring along with SOD, as high amounts of sCOD leached from the tire chips in the beginning of the study, reaching sCOD concentrations of 120-160 mg L-1 then decreasing after day 10 of operation of stage 2. Sulfate concentrations from stage 2 for each side were low until the last 10 days of the study, with an average of 16.43 ± 11.36 mg L-1 SO42--S from R-2 and an average of 16.80 ± 7.98 SO42--S for FF-2 for the duration of the study, however at the end of the study when forward flow rates increased, SO42--S concentrations increased to 32 mg L-1 for R-2 and 40 mg L-1 for FF-2. Similar performance was observed in the FF system as the bench scale reactor tests. The second part of the research focused on the findings from a study of a Particulate Pyrite Autotrophic Denitrification (PPAD) process that uses pyrite as the electron donor and nitrate as the terminal electron acceptor in upflow packed bed bioreactors. The advantages of using pyrite as an electron donor for denitrification include less sulfate production and lower alkalinity requirements compared with SOD. The low alkalinity consumption of the PPAD process led to comparison of PPAD performance with and without oyster shell addition. Two columns were operated side-by-side, one packed with pyrite and sand only (P+S), while another one was packed with pyrite, sand and oyster shell (P+S+OS). Sand was used as a nonreactive biofilm carrier in the columns. My contribution to this research was to carry out Scanning Electron Microscopy-Energy-Dispersive X-Ray Spectroscopy (SEM-EDS) analysis to support the hypothesis that oyster shell contributes to nitrogen removal because it has a high capacity for biofilm attachment. SEM analysis showed that oyster shell has a rough surface, supported by its high specific surface area, and that there was more biofilm attached to oyster shell than pyrite or sand in the influent to the column. EDS results showed a decrease in atomic percentages for pyrite sulfur in the effluent of both columns (59.91% ± 0.10% to 53.94% ± 0.37% in P+S+OS column and to 57.61% ± 4.21% in P+S column). This finding indicated that sulfur was oxidized more than iron and/or the accumulation of iron species on the pyrite surface and supports the coupling of NO3- reduction with pyrite oxidation.

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Gkiouzepas, Stylianos. "Nitrogen and phosphorous removal from groundwater using waste materials". Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27454.

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The occurrence of high nitrate and phosphate levels in groundwater is a worldwide problem. The study of suitable methods to remove these compounds is crucial for the long-term environmental health of ecosystems. Nitrification and eutrophication occur in areas where there is extensive human activity for agricultural cultivations and industries. The study area for this project, Greece, is affected by nitrate and phosphate in groundwater. The extensive use offertilizers and pesticides and the drilling of groundwater wells have reduced the quality of water on many Greek islands. A case study of Samos Island next to the borders between Greece and Turkey, support the problem in high nitrogen levels. The aim of this study was to determine if passive engineering solutions could be designed using cheap and easily available local materials that can remove nitrogen and phosphorous compounds from groundwater. This study focus on laboratory based experiments with columns. The substrate materials were selected with specific criteria. In the first experiments materials that have already investigated and groundwater from the area that Nitrabar project took place in Northern Ireland was used,where known denitrifier bacteria already exist. The next experimental section used new materials for nitrate and phosphate reduction including perlite, tea waste materials and hazelnut husk wastes. In the this experiment these substrate materials were investigated in batch and column experiments, in short and long term time periods, and with two water sources, tap water and groundwater (Scotland, UK).The investigation of denitrification process in all experiments proved successful. In all experiments removal of nitrate and phosphate compounds was observed. The best reduction was found in the last experiment with the new substrate materials showing a reduction between 90-99% for all nitrogen compounds and the reduction of phosphate levels was more than 80% at all cases. The degradation rates calculated were similar to the previous experiments showed efficiency with the new waste materials. It was interesting to note that each experiment showed an initial growth phase / adaptation lag phase followed by a stable biodegradation phase.

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Takach, Tibor. "Total nitrogen removal using a pure-oxygen predenitrification configuration". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ35086.pdf.

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Kosari, Fatemeh. "Nitrogen removal from wastewater through partial nitrification/ Anammox process". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36921.

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Nitrogen removal from wastewater through partial nitrification/Anammox was investigated. The objectives of the research were divided to three distinctive and related areas: Partial Nitrification (PN) process, Anammox reaction and green house gases emission from partial nitrification and Anammox reactor. In the PN process, research objectives were to determine: 1) the effect Dissolved Oxygen concentration, alkalinity on the PN reaction 2) evaluation of continuous moving bed biofilm reactor (MBBR) and sequencing batch reactor (SBR) for partial nitrification process. The main goals of the Anammox process study was to investigate: 1) parameters, which affect the Anammox process 2) evaluation of continuous moving bed biofilm reactor, hybrid reactor and up-flow fixed-bed reactor for the Anammox process. In the last stage, N₂O and NO emissions from both partial nitrification and Anammox reactor under various operating conditions were determined. Partial nitrification in the sequencing batch reactor was more efficient, compared to continuous moving bed biofilm reactor. Alkalinity was investigated as a limiting factor for oxidizing more ammonium to nitrite in the PN reactor. The effluent of the MBBR contained 59.7% ammonium, 31.7 % nitrite and 8.5 % nitrate and gaseous products, such as nitrous oxide and nitrogen as initial nitrogen load. Whereas, the SBR could convert more than 45% of the ammonium to nitrite; in fact, the effluent of the SBR reactor contained 45.1% ammonium, 45.1% nitrite and 1.9% nitrate, as initial nitrogen load. Subsequent Anammox treatment, after the MBBR, resulted in 38.8% additional ammonium removal and nitrite removal of 83.1 %. As a result, total ammonia removal in the combined system reached 79.1% and total nitrogen removal was 56.8 %. The Hybrid Anammox reactor removed an average of 55.8% of NH₄-N, versus 48.3% NH₄-N removal in the up-flow fixed-bed reactor. Nitrite removal in the hybrid and up-flow fixed-bed Anammox reactor was 80.8% and 62.5%, respectively. This research indicates that nitrous oxide and nitric oxide emission from partial nitrification at DO being controlled at 2 mg/L were 2.6±0.2% and 0.6±0.3% as nitrogen load, respectively. Relatively low N₂O of 0.15±0.02% was observed from the Anammox reactor, compared to partial nitrification and NO emissions was none detected.

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Tiefenau, Börge Mike. "Is phosphorus limiting the nitrogen removal in constructed wetlands?" Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-26257.

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Two mesocosm studies were performed in a laboratory to figure out the relevance of the phosphorus concentration to the nitrogen removal in wetlands. The main intention was to see if phosphorus is limiting the process of denitrification. In both experiments, plastic beakers (n=20) were filled with inlet water and plant litter material from the ground of a constructed wetland near Halmstad, Sweden.. The litter consisted mainly of dead leaves of Phragmites australis and the water, originating from an agricultural site, had a high concentration of total nitrogen (around 9 mg/L), but a low concentration of phosphorus (around 20 µg/L). The experiment was performed in darkness and in the mesocosms prevailed anaerobic conditions. Half of the beakers were filled with phosphorus enriched water and water samples were obtained at several times and analyzed for nitrate, total nitrogen and total phosphorus to determine the nitrogen removal. In addition the plant material was analyzed for nitrogen and carbon content before and after the experiment with a carbon/nitrogen-analyzer. The mean removal rates of nitrogen were higher in the mesocosms which were treated with additional phosphorus. In a long-term perspective from the second experiment, the mean removal rates are declining faster in the non phosphorus treated beakers. The analysis of the plant litter material could not show if nitrogen was removed from systems through denitrification or just taken up and stored by microorganisms. The experiment was carried out under controlled conditions. The results show that the effect of P on denitrification is not completely understood yet and further research especially on the N uptake by microorganisms and long-term experiments are needed.

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Banjade, Sarita. "Anaerobic / Aerobic Digestion for Enhanced Solids and Nitrogen Removal". Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/36128.

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Anaerobic digestion of wastewater sludge has widely been in application for stabilization of sludge. With the increase in hauling cost and many environmental and health concerns regarding land application of biosolids, digestion processes generating minimized sludge with better effluent characteristics is becoming important for many public and wastewater utilities.

This study was designed to investigate the performance of anaerobic-aerobic-anaerobic digestion of sludge and compare it to anaerobic-aerobic digestion and single stage mesophilic digestion of sludge. Experiments were carried out in three stages: Single-stage mesophilic anaerobic digestion (MAD) 20d SRT; Sequential Anaerobic/Aerobic digestion (Ana/Aer); and Anaerobic/Aerobic/Anaerobic digestion (An/Aer/An). The Anaerobic/Aerobic/Anaerobic digestion of sludge was studied with two options to determine the best option in terms of effluent characteristics. The two sludge withdrawal options were to withdraw effluent from the anaerobic digester (An/Aer/An â A) or withdraw effluent from the aerobic digester (An/Aer/An â B). Different operational parameters, such as COD removal, VS destruction, biogas production, Nitrogen removal, odor removal and dewatering properties of the resulting biosolids were studied and the results were compared among different processes.

From the study, it was found that An/Aer/An â B (wastage from aerobic reactor) provided better effluent characteristics than An/Aer/An â A (wastage from anaerobic reactor), Ana/Aer or conventional MAD. The study also shows that the Anaerobic/Aerobic/Anaerobic (An/Aer/An, with wastage from the aerobic or anaerobic digester) digestion of the sludge can improve the biosolids quality by improving the dewatering capabilities, with lower optimum polymer dose, reduced CST and increased cake solid concentration, and reduce the odor generation from the biosolids.

Both An/Aer/Ana â A and An/Aer/An â B gave 70% VS removal, compared to 50% with single MAD and 62% with only Ana/Aer. COD removal of both An/Aer/An â A and An/Aer/An â B was 70%, while it was 50% and 66% for single MAD and Ana/Aer respectively. In the aerobic reactors of Ana/Aer and An/Aer/An - B, nitrification and denitrification with removal of nitrogen was observed. The An/Aer/An â B system had more ammonia and TKN removal (70%) than Ana/Aer (64%).

The effluent from each stage was analyzed for dewatering ability, cake solid concentration and odor production potential. Compared with a single Ana/Aer system, the extra anaerobic step in An/Aer/An â A and â B reduced polysaccharides in the effluent. The Ana/Aer system released less protein than the conventional MAD system and the addition of the second anaerobic step - especially with system An/Aer/An â B (discharge from aerobic reactor) - greatly reduced protein, resulting in improved dewaterability and less polymer demand. An/Aer/An (both of the options: A and B) had lower CST than single MAD (both 15d and 20d SRT) and Ana/Aer. Compared to Ana/Aer, a reduction of 52% for An/Aer/An â A and 20% for An/Aer/An â B in polymer dose requirement was observed, indicating improved dewatering characteristics. The An/Aer/An â B has higher biosolid cake concentration than MAD or Ana/Aer. The results showed that An/Aer/An (both options: A and B) biosolid had lower odor generation potential than single MAD (15d and 20d SRT) or Ana/Aer. Of all the stages,the An/Aer/An â A and â B system, generated odor which peaked at shorter time and lasted for shorter duration of time.
Master of Science

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Halvarsson, Björn. "Interaction analysis and control of bioreactors for nitrogen removal". Licentiate thesis, Uppsala universitet, Avdelningen för systemteknik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-85853.

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Efficient control of wastewater treatment processes are of great importance. The requirements on the treated water (effluent standards) have to be met at a feasible cost. This motivates the use of advanced control strategies. In this thesis the activated sludge process, commonly found in the biological wastewater treatment step for nitrogen removal, was considered. Multivariable interactions present in this process were analysed. Furthermore, control strategies were suggested and tested in simulation studies. The relative gain array (RGA), Gramian based interaction measures and an interaction measure based on the H2 norm were considered and compared. Properties of the H2 norm based measure were derived. It was found that the Gramian based measures, and particularly the H2 norm based measure, in most of the considered cases were able to properly indicate the interactions. The information was used in the design of multivariable controllers. These were found to be less sensitive to disturbances compared to controllers designed on the basis of information from the RGA. The conditions for cost-efficient operation of the activated sludge process were investigated. Different fee functions for the effluent discharges were considered. It was found that the economic difference between operation in optimal and non-optimal set points may be significant even though the treatment performance was the same. This was illustrated graphically in operational maps. Strategies for efficient control were also discussed. Finally, the importance of proper aeration in the activated sludge process was illustrated. Strategies for control of a variable aeration volume were compared. These performed overall well in terms of treatment efficiency, disturbance rejection and process economy.

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Yan, Qingmei. "Biological nitrogen removal of saline wastewater by ammonium oxidizers". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42182116.

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Hamilton, Ryan K. "Modeling biological nitrogen removal with denitrification enzyme parameter estimation". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0012002.

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Rycewicz-Borecki, Malgorzata. "Stormwater Bioretention: Nitrogen, Phosphorous and Metal Removal by Plants". DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4597.

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Stormwater runoff may contain high levels of pollutants and is regulated by the Federal National Pollution Discharge Elimination System (NPDES). Stormwater bioretention (BR) systems are often used to satisfy these regulations. BR systems collect accumulated runoff that leaches into groundwater. A greenhouse study evaluated nutrient and metal removal among plant species that are typically found growing in BR systems. A field demonstration study assessed citric acid enhanced metal bioaccumulation potential under typical BR system conditions. The greenhouse experiment examined pollutant retention, and bioaccumulation potential for six plant species undergoing three hydraulic and pollutant loads. Results verified there was 98% recovery of total phosphorous over the study period. Biomass increased with higher hydraulic and pollutant loads for all species. Phragmites australis, Carex praegracilis, and Carex microptera took up significantly more total phosphorous and nitrogen mass into shoots than Typha latifolia, Scirpus valid us, and Scirpus acutus. This study also found that 89% of applied metals were removed within the top 27 em of soil in all treatments. Similar results were found regarding copper, lead, and zinc concentrations and bioaccumulation. Carex praegracilis, and Carex microptera exhibited higher metal distribution in plant tissue and exfiltrate, and lower distribution in the soil media than the other species. This indicated species differences in biological and chemical processes taking place within the simulated BRsystems. The field experiment investigated citric acid enhanced metal bioaccumulation potential among three different plant species under representative BR conditions. Citric acid significantly increased metal concentrations in the soil pore water for the planted treatments, but this did not result in increased metal uptake into plant tissue. However, notable differences were found among species, where Carex microptera accumulated more AI, Cr, Cu, and Fe in the above ground tissue than Helianthus maximiliani and Typha /atifolia (except for Cu in Helianthus). These results provide greater insight into the biological and chemical process that affect transport, uptake and translocation of nutrients and metals, and confirm the importance of species selection in BR systems to optimize nutrient and metal retention and recovery from stormwater runoff to minimize subsequent groundwater pollutant loading.

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Jensen, Keith R. "Effects of Integrated Fixed Film Activated Sludge on nitrogen removal in biological nutrient removal systems". Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-01312009-063219/.

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Flynn, Nicola Jane. "Nitrogen interactions between floodwater and floodplain soils". Thesis, Royal Holloway, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311972.

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Codal, Ahmet. "Modeling Of Nitrogen Removal In A Membrane Biological Treatment Process". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12610212/index.pdf.

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Biological nitrogen removal was simulated for a Vacuum Rotating Membrane (VRM) type membrane bioreactor (MBR) operated in METU campus. In order to simulate the biological MBR plant, a dynamic model that describes the process is needed. In this thesis, the Activated Sludge Model No.1 (ASM1), which still is the most widely used model developed by the International Association on Water Quality (IAWQ), has been used to simulate the carbon oxidation, nitrification and denitrification processes occurring in the plant using AQUASIM software package. Once the model was established, sensitivities of the model parameters were analyzed. Then, parameter estimation was carried out for the optimization of the sensitive parameters. As we have several distinct data sets available two parallel modeling study was carried out for the calibration of the model. Finally, the calibrated model by different data sets was validated by using the remaining data sets. The model results were consistent with the measured data especially in terms of MLSS concentration in the system. However model results for the nitrogen removal were not extremely successful
the reason for this might be the inadequate available data on nitrification-denitrification process occurring in the system.

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Chipello, Peter Luke, i Peter Luke Chipello. "Nitrogen removal and transformations during simulated soil aquifer treatment (SAT)". Thesis, The University of Arizona, 1999. http://hdl.handle.net/10150/626907.

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Nitrogen transformations were studied in 1-meter soil columns fed with primary, secondary, or nitrified-secondary effluents. The columns were packed with sand or sandy loam and operated on 7-day wet, 7-day dry cycles. Cumulative total nitrogen (TN) removals during application of secondary effluent or ozonated secondary effluent were 5% for sand and 38% for sandy loam columns. Significant TN removals were achieved using primary/nitrified-secondary effluent blends. Cumulative TN removal was 44% for three cycles of operation using a 50/50 blend of primary and nitrified-secondary effluent in sand. In a sandy loam column, cumulative TN removals were 32%, 54%, and 72% for primary/nitrified-secondary blend ratios of 25/75, 35/65 and 50/50, respectively. Assuming a mechanism of denitrification, the supply of carbon was estimated to be less than a third of what would be required to account for observed TN removals during application of primary/nitrified-secondary blends, suggesting the need to consider other possible nitrogen removal mechanisms.

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21

Gut, Luiza. "Assessment of a partial nitritation/Anammox system for nitrogen removal". Licentiate thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-604.

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Kyambadde, Joseph. "Optimizing processes for biological nitrogen removal in Nakivubo Wetland, Uganda /". Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134.

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Traband, Jason John. "Removal of wastewater nitrogen and phosphorus by an oligohaline marsh". College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/255.

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Thesis (M.S.) -- University of Maryland, College Park, 2003.
Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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24

楊龍元 i Lung-yuen Christopher Yeong. "Removal of wastewater cod and nitrogen using fibrous packing media". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31210636.

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Malovanyy, Andriy. "Anammox-based systems for nitrogen removal from mainstream municipal wastewater". Doctoral thesis, KTH, Mark- och vattenteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202960.

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Nitrogen removal from municipal wastewater with the application of deammonification process offers an operational cost reduction, especially if it is combined with a maximal use of organic content of wastewater for biogas production. In this thesis, two approaches for integration of the deammonification process into the municipal wastewater treatment scheme were studied. The first approach is based on ammonium concentration from municipal wastewater by ion exchange followed by biological removal of ammonium from the concentrated stream by deammonification process. Experiments with synthetic and real municipal wastewater showed that strong acid cation resin is suitable for ammonium concentration due to its high exchange capacity and fast regeneration. Since NaCl was used for regeneration of ion exchange materials, spent regenerant had elevated salinity. The deammonification biomass was adapted to NaCl content of 10-15 g/L by step-wise salinity increase. The technology was tested in batch mode with 99.9 % of ammonium removal from wastewater with ion exchange and up to 95 % of nitrogen removal from spent regenerant by deammonification process. The second studied approach was to apply anammox process to low-concentrated municipal wastewater in a moving bed biofilm reactor (MBBR) and integrated fixed film activated sludge (IFAS) system without a pre-concentration step. After a 5 months period of transition to mainstream wastewater the pilot plant was operated during 22 months and stable performance of one-stage deammonification was proven. Clear advantage of IFAS system was shown. The highest stable nitrogen removal efficiency of 70 % and a nitrogen removal rate of 55 g N/(m3·d) was reached. Moreover, the influence of operation conditions on competition between ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied by literature review, batch tests and continuous pilot plant operation.

QC 20170309

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26

Whichard, David P. "Nitrogen Removal From Dairy Manure Wastewater Using Sequencing Batch Reactors". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34412.

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The purpose of this research was to characterize a flushed dairy manure wastewater and to develop the kinetic and stoichiometric parameters associated with nitrogen removal from the wastewater, as well as to demonstrate experimental and simulated nitrogen removal from the wastewater. The characterization showed that all the wastewaters had carbon to nitrogen ratios large enough for biological nitrogen removal. Analysis of carbon to phosphorus ratios showed that enough carbon is available for phosphorus removal but enough may not be available for both nitrogen and phosphorous removal in anaerobically pretreated wastewater. In addition, kinetic and stoichiometric parameters were determined for the biological nitrogen removal in sequencing batch reactors for the dairy manure wastewater. Results showed that many parameters are similar to those of municipal wastewater treatment systems. This characterization and the derived kinetic and stoichiometric parameters provided some of the information necessary for development of a nitrogen removal process in a sequencing batch reactor. Lab scale treatment of a 1:2 dilution of the anaerobically pretreated wastewater was demonstrated. Treatment was able to achieve between 89 and 93% removal of soluble inorganic nitrogen as well as up to 98% removal of biodegradable soluble and colloidal COD. In addition, a solids removal efficiency of between 79 and 94% was achieved. The lab scale treatment study demonstrated that sequencing batch reactors are capable of achieving high nitrogen removal on wastewaters with the carbon to nitrogen ratios of the dairy manure wastewater. Model simulations of the treatment process were used to develop a sensitivity analysis of the reactor feed configuration as well as the kinetic and stoichiometric parameters. The analysis of the feed configuration demonstrated the advantage of decreasing the amount of feed that is fed in the last feed period so that the effluent nitrate will be minimized. The analysis indicated that the autotrophic growth rate is one of the most important parameters to measure while error in the heterotrophic decay or yield values can lead to miscalculations of oxygen required for treatment.
Master of Science

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27

Guan, Lu. "Nitrogen Removal from Closed Aquaculture System by Bio-electrochemical System". Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/91468.

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Removal of nitrogen elements in culture water is one of the major concerns in recirculating aquaculture system (RAS). Maintaining a low concentration of nitrogen compounds is essential for a good quality of aquaculture production. Due to fish is very sensitive to the toxic ammonium/ammonia, nitrification biofiltration tank is often an integrate part of filtration in RAS to remove ammonium via nitrification. However, nitrate accumulation via nitrification in RAS is often observed during the operation, which is usually solved by replacing with the fresh water into the system. With the concern of water consumption, bio-electrochemical system (BES) is introduced in this study to realize simultaneous nitrate removal for the system while generating the electricity through electron transferring. A microbial fuel cell (MFC) with an anion exchange membrane (AEM) was constructed. The removal of nitrate from aquaculture water generated from RAS was achieved by nitrate migration across the AEM and heterotrophic denitrification in the anode chamber. To further investigate the potential application of BES in RAS, the cathode chamber was incubated with biofilm to do the nitrification while the denitrification processing in the anode chamber. The study gave a total inorganic nitrogen removal efficiency of 38.72% ± 4.99, and a COD removal of 86.09% ± 9.83. The average daily electricity generation was 67.98 A m-3 ± 13.91, and nitrate-nitrogen concentration remained at 21.02 ± 2.62 mg L-1 throughout the experiment. These results of treating aquaculture water indicate that BES has a potential to install within RAS for enhanced nitrogen removal.
MS

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MENG, YUANHANG. "NITROGEN REMOVAL UPGRADE OF TWO PILOT-SCALE WASTEWATER TREATMENT PLANTS". University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1171931949.

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Scott, Daniel. "Biological Nitrogen Removal in a Gravity Flow Biomass Concentrator Reactor". University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1298323356.

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30

Samuelsson, Pär. "Modelling and control of activated sludge processes with nitrogen removal". Licentiate thesis, Uppsala universitet, Avdelningen för systemteknik, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-86006.

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Stricter legislations on nitrogen removal together with increasing wastewater loads have successively increased the need for optimization and control of activated sludge processes. The aim of this thesis is primarily to propose and illustrate methods for modelling and control of activated sludge processes, and thus possibly improve process efficiency. The first part of this thesis describes a JAVA based simulator of the activated sludge process. Its features are discussed, and some control strategies are illustrated. The second part of the thesis presents a simple model based feedforward controller for controlling the nitrate level by using an external carbon source. Several simulation examples are used to illustrate the control law. In the third part, a model based strategy for control of the ammonium level by manipulating the aeration volume in the activated sludge process is presented. The strategy is based on exact linearization combined with some logical programming rules in order to deal with discrete volume changes. The control law is also evaluated in simulations.

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Yeong, Lung-yuen Christopher. "Removal of wastewater cod and nitrogen using fibrous packing media /". [Hong Kong : University of Hong Kong], 1991. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13193429.

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32

Baloch, Muhammad Imran. "Carbon and nitrogen removal in a granular bed baffled reactor". Thesis, Abertay University, 2004. https://rke.abertay.ac.uk/en/studentTheses/bab9fa75-37e0-481b-b442-33a5793515c3.

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One of the primary concerns for the treatment of high strength carbonaceous wastewaters in anaerobic systems is to achieve an optimum growth environment for acidogenesis and methanogenesis. Such wastewaters with high nutrient levels could cause additional problems as anaerobic units are usually designed for the removal of organic matter. In addition, nitrate inhibition to methanogenesis in anaerobic environment could cause further problems during treatment. Therefore, a type of high rate anaerobic system is required which could accommodate nitrogen removal in addition to organic carbon removal, and comply with the increasingly stringent discharge standards adopted by environmental protection agencies worldwide. This research was carried out by developing a new reactor by using a bed of anaerobic granular sludge in an anaerobic baffled reactor, the granular bed baffled reactor (GRABBR). The aims of this study were to investigate the performance of GRABBR in terms of treatment efficiency for carbon and nitrogen removal, long term and shock load stability, occurrence and effectiveness of phase separation, characteristics of granular biomass in different phases, and to examine the physical, microbiological and kinetic parameters of biomass. A 10 litre GRABBR divided into five equal sized compartments was operated under mesophilic (35°C) conditions. The GRABBR system achieved high chemical oxygen demand removal, biomass retention and methane yield under various operational strategies, particularly at high organic loading rates (OLRs), with synthetic glucose and brewery wastewaters. Phase separation between acidogenesis and methanogenesis mainly occurred at high OLRs. The reactor configuration and microbial environment encouraged the acidogenic dominant zone to produce intermediate products suitable for the methanogenic dominant zone. Acidogenesis in the upstream compartments of GRABBR caused breaking and flotation of granular sludge, along with the formation of microbial mass identified as mainly Gram-negative Klebsiella pneumoniae, while downstream methanogenic compartments retained the original granular structure. The reactor was efficiently operated at high OLR with short hydraulic retention time (HRT) on a long-term basis. The system was capable of treating highly varying flow rates. Simultaneous denitrification and methane production was observed in GRABBR during nitrate addition in the acidogenic and methanogenic dominant zones. It is shown that the microbial arrangement in a layered granular structure, containing vast diversity of species with strong association of facultative and methanogenic populations, and phase separation characteristics of the GRABBR, brought about simultaneous denitrification and methane production. No noticeable ammonification was observed with glucose and brewery wastewaters during nitrate reduction. The simpler forms of carbon sources, like acetate and VFA, were found to be a more efficient substrate in terms of carbon and nitrate removal than glucose. The presence of simpler forms of substrate and higher concentrations of methanogenic granules exhibited higher nitrate and carbon removal rates in the methanogenic dominant zone than the acidogenic dominant zone of GRABBR. This study demonstrated that the combination of granular bed, compartmentalisation and plug flow in a single system could achieve ideal anaerobic configuration for wastewater treatment to accomplish carbon and nitrogen removal. The findings of this research suggest that the application of a GRABBR is suitable for the treatment of multiple pollutants of complex or high strength wastewaters, where each phase or compartment acts as a separate specialised treatment unit.

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Peng, Wei. "Digestate application in landfill bioreactors: Nitrogen removal and digestate stabilization". Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3427186.

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Anaerobic digestion (AD) of organic fraction of municipal solid waste (OFMSW) or food waste has aroused attention increasingly as it can achieve both environment and economic benefits. The by-product from AD, the digestate, still rich in putrescible components and nutrients, is mainly considered for reutilization as a bio-fertilizer or a compost after its treatment. However, the limitations exist for digestate agricultural application because of nutrients surplus, fertilization seasons, high cost of long-distance transportation and low market acceptance. Besides, digestate from OFMSW and food waste needs to be disposed as “waste” when it does not comply with the regulation requirements. The chapter 1 of the work is an overview on the digestate characterizations, regulations of agricultural use and application techniques. The concept of Back to Earths Alternatives (BEAs) introduced in the literature review involves that the residues, after appropriate treatment, "should be returned to their non-mobile state as they were before they were extracted from the ground to be used as raw materials ". The specific aim of BEA is to bring elements and materials back into the environment either as soil amendments or functional components for landfills. The novel concept can deal with the two dilemmas of digestate management and achieve the close of material loop. Aim of the Chapter 2 was to develop an alternative option to use digestate to enhance nitrified leachate treatment through a digestate layer in landfill bioreactors. Two identical landfill columns (Ra and Rd) filled with the same solid digestate were set and nitrified leachate was used as influent. Nitrate nitrogen removal efficiency of 94.7% and 72.5% were achieved after 75 days and 132 days, respectively. These results suggest that those solid digestates could be used in landfill bioreactors to remove the nitrogen from old landfill leachate. The study of Chapter 3 aims to evaluate the application of digestate in simulated landfill columns to enhance nitrogen conversion via short-cut nitrogen removal. Two identical simulated landfill reactors filled with solid digestate were setup and partial nitrified leachate was fed through the columns. After 109 days of operation, the average nitrite nitrogen and nitrate nitrogen removal efficiencies were 92.6% and 85.8%, respectively. The high concentrations of nitrite (1004 mg-N/L) did not significantly inhibit methane production during denitrification in the digestate-added landfill columns. Aim of the Chapter 4 was to use a digestate layer in aged refuse bioreactors to enhance the denitrification capacity of aged refuse, stabilize digestate and mitigate the ammonia emission from digestate leaching with leachate recirculation. Six identical landfill columns filled with 0% (R0), 5% (R5), and 15% (R15) of solid digestate above aged refuse, were set and nitrified leachate was periodically fed and recirculated. Nitrate removal rate in R5 and R15 were 3.4 and 10.0 times higher than that of control (no digestate added). The results showed that instead of land use, solid fraction of digestate could be exploited as an inexpensive functional layer embedded in old landfill site to enhance denitrification capacity and achieve digestate stabilization with little ammonia leaching from digestate. In conclusion, solid digestate was effective in reducing the oxidized nitrogen (nitrate or nitrite) content of nitrified leachate or partial nitrified leachate. Meanwhile, the organic matter content of the solid digestate was degraded under anaerobic conditions with low methane emission. Solid digestate with or without further treatment can be utilized as an engineered landfill biocover. Besides, solid digestate could be applied in external reactors to ex-situ treat nitrified leachate. At last, solid digestate can be used as functional layer embedded landfill to removal nitrogen in those old landfills with low denitrification capacities.

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MARAZZI, FRANCESCA ALICE. "Growth of microalgal biomass on supernatant from biosolid dewatering". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2017. http://hdl.handle.net/10281/158195.

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Questa tesi è volta a valutare l’integrazione delle microalghe in impianti di depurazione con il duplice scopo di rimuovere azoto e produrre biomassa da convogliare ai digestori anaerobici. In particolare, questa tesi si concentra sulla identificazione dei acque reflue di tipo agricolo e civile (come effluenti, centrati, digestato, e una miscele di loro) più idonee ad essere usate come substrato per la cultura microalghe. Il capitolo 2 contiene un resoconto che tratta degli attuali approcci per la produzione di biomassa microalgale utilizzando diversi tipi di rifiuti. Il cuore della mia sperimentazione è descritta nei capitoli 3-7; in particolare, il capitolo 3 mostra i risultati di test nei quali il centrato di origine civile è stato usato come substrato per la produzione di biomassa algale. La novità dello studio consiste: (i) nell’uso di centrato tal quale come substrato di crescita, mentre la maggior parte dei dati di letteratura sono stati ottenuti su refluo pretrattato, (ii) nell'uso di un fotobioreattore alimentato in continuo e (iii) nello svolgimento delle prove in condizioni ambientali naturali. Questo lavoro ha dimostrato che le microalghe (Chlorella sp e Scenedesmus sp) sono in grado di crescere facilmente sul centrato e il loro tasso medio di crescita specifico, che varia tra 0,14-0,16 d-1 è comparabile con i dati di letteratura. Anche i test di produzione di biometano (BMP) hanno mostrato buoni risultati: il BMP ottenuto dalla biomassa microalgale è più lento rispetto ai fanghi, ma il suo valore finale è leggermente superiore (208 mLCH4 gVS-1 vs 190 mLCH4 gVS-1). Nel capitolo 4 sono stati studiati diversi reflui agricoli, che potenzialmente potrebbero essere usati come substrato di crescita per le microalghe. Le analisi chimiche e fisiche hanno dimostrato che le frazioni liquide di letame suino potrebbe essere utilizzato a tale scopo. Nel capitolo 5 viene proposto un pre-trattamento con carboni attivi (AC) del centrato di origine suina per facilitare la crescita microalghe. Sono stati testati diversi dosaggi di carbone attivo e il dosaggio di 40 g L-1 e 10 minuti di tempo di adsorbimento sembra essere il più promettente. Nello specifico la riduzione della torbidità del refluo è stata pari all’88%. Gli incoraggianti risultati in scala di laboratorio presentati nel Capitolo 4 e 5 giustificano le successive sperimentazioni su scala pilota, utilizzando reflui di origine agricola come fonte di nutrienti per microalghe. Nel capitolo 6 viene presentato il lavoro in scala pilota, un fotobioreattore è stato installato presso una azienda agricola nel Nord Italia. Durante la sperimentazione, la densità microalghe è rimasta abbastanza costante, intorno al valore medio di 0,55 gTS/l, mentre le efficienze di rimozione dell’azoto totale e di N-NH4+ erano entrambe molto alte (in media 80 e 87%, rispettivamente). L'obiettivo principale del capitolo 7 è volto a trovare la migliore tecnica di separazione della biomassa algale dal substrato di crescita. In questa sezione sono stati testati tre processi di separazione liquido/solido della biomassa microalgale: (i) sedimentazione per gravità; (ii) centrifugazione, (iii) flocculazione. Le principali conclusioni sono riportate nel capitolo 8: l'integrazione delle microalghe negli schemi di trattamento delle acque reflue offre una strategia economicamente fattibile e ambientalmente sostenibile; la crescita microalgale è fortemente influenzata dalle condizioni ambientali; il pretrattamento del digestato, combinato con i processi di strippaggio e adsorbimento con carbone attivo potrebbe migliorare notevolmente l'efficacia della coltivazione delle microalghe; le microalghe potrebbero essere co-digerite con fanghi di scarto senza effetti negativi sul consorzio anaerobico, nonostante le biomassa microalgale abbia alcuni punti critici come la parete cellulare resistente che limita la sua bioconversione.
This thesis deals with the feasibility of including a mixed microalgal community in a real wastewater treatment sequence with the double aim of removing nitrogen and producing biomass to feed the anaerobic digesters. In particular, this thesis focuses on identification of relevant waste streams from agricultural and municipal activities (like effluents, centrates, digestates, and a mixture of them) as a substrate for microalgal culture. Chapter 2 contains a critical review, this manuscript summarizes the current approaches to microalgal biomass production using waste streams, including wastewater, waste or CO2-enriched gas (flue gas and biogas), waste organics (i.e., crude glycerol) and waste heat, as well as the primary common operational challenges and corresponding mitigation strategies involved in culturing approaches. The core of experimentation is described in Chapters 3-7 using wastewater from urban or agriculture activity as a substrate for microalgal culture. In particular, Chapter 3 shows the results of experimentation using municipal centrate to produce biomass to feed the anaerobic digesters removing at the same ammonia nitrogen. The novelty of the study consists in the use of raw centrate from urban wastewater treatment plant as a substrate to grow microalgae, while the majority of literature data were obtained on pre-treated (diluted and/or supplemented and/or furtherly clarified) centrate samples, in the use of a continuously fed PhotoBio Reactor (PBR) operated under natural, uncorrected environmental conditions. This work demonstrates that microalgae (Chlorella sp and Scenedesmus sp) are able to easily grow on the centrate. The average specific growth rate in indoor and outdoor batch tests is satisfactory and comparable with literature data, ranging between 0.14-0.16 d-1. During the continuous test the average biomass production is 50 mgTSS L-1 d-1 and the difference between N-NH4 concentration in the influent and in the effluent demonstrates an important removal. Also BMP tests showed good results: the production of biomethane from algal biomass is slower than from sludge, but its final value is slightly higher than that from waste sludge (208 mLCH4 gVS-1 vs. 190 mLCH4 gVS-1). Wastewaters from agricultural activities are the subject of Chapter 4, chemical and physical analyses showed that the liquid fractions of swine manure and the first effluent could be suitable for algal treatment, while the other samples had unacceptable levels of both solid content and turbidity which would seriously limit light penetration. The papers in Chapter 4 and Chapter 5 report the results obtained in lab-scale tests using the agro wastes which had been shown to be more suitable. In Chapter 5 a new approach is proposed using Activated Carbon (AC) from wood as a pre-treatment to facilitate microalgal growth, without addition of tap water for dilution. The optimal optical density values were obtained with 40 g L-1 of AC dosage and 10 minutes adsorption time, corresponding to 88% of turbidity reduction. Then semi-continuous microalgae culturing were tested using adsorbed and not adsorbed liquid centrate (3 replicates). The encouraging lab scale results presented in Chapter 4 and Chapter 5 justify further pilot-scale experimentation, using agrowastes as the nutrient source for microalgae, presented in Chapter 6. The pilot scale (PBR) was installed at a piggery farm in Northern Italy. During the culturing period, microalgal density remained quite constant, around the average value of 0.55 gTSS/L, and the efficiency of Total Nitrogen and of N-NH4+ removal were both very high (on average 80 and 87%, respectively). The search for the best biomass harvesting technique is the main objective of Chapter 7. In this point, microalgal biomass is processed by three solid/liquid separation processes: gravity settling; centrifugation tests, flocculation tests. The main conclusions are reported in Chapter 8.

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Kallner, Bastviken Sofia. "Nitrogen removal in treatment wetlands : Factors influencing spatial and temporal variations". Doctoral thesis, Linköpings universitet, Ekologi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7564.

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Decreasing the nitrogen transport from land to surrounding seas is a major task throughout the world to limit eutrophication of the coastal areas. Several approaches are currently used, including the establishment of wetlands, to decrease the transport of nitrogen. Wetlands represent ecosystems where the nitrogen removal from water can be efficient given that they are appropriately designed. The aim of this thesis was to investigate and quantify the effect of critical factors that regulate the nitrogen removal in wetlands, and to develop better guidelines for wetland design. Studies were performed at different scales, from microcosms to full scale wetlands, and methods included modelling, mass balance calculations and process studies. A first order rate model was used to simulate the nitrogen transformations in two large wetlands treating wastewater containing both ammonium and nitrate nitrogen. It was found that the dynamics of the main itrogen transformation processes could not be satisfactorily described using this approach. Large wetlands containing vegetation are complex ecosystems, and the process rates vary in both time and space. The great diversity of microenvironments favours different nitrogen processes, and large differences in potential nitrification and denitrification rates were found between different surface structures within a wetland. The results from microcosms measurements showed that the highest potential for nitrification was on surfaces in the water column, while the denitrification capacity was highest in the sediment. For the sediment denitrification capacity, the plant community composition was shown to be of major importance primarily by supplying litter serving as a carbon and energy source, and/or attachment surfaces, for denitrifying bacteria. Denitrification rates may be affected more than three fold by different types of litter and detritus in the sediments. Intact sediment cores from stands of the emergent plants Glyceria maxima and Typha latifolia had higher denitrification potential than sediment cores from stands of the submersed plant Potamogeton pectinatus. However, the quality of the organic material for the denitrifying bacteria was highest in G. maxima and P. pectinatus stands. All sediment cores from the wetland were limited by carbon, and the lower denitrification capacity of the submersed plant, P. pectinatus, was likely due to lower amounts of organic matter. However, in another wetland, intact cores from stands of the submersed plant Elodea canadensis had a higher denitrification capacity than the cores from stands of T. latifolia and Phragmites australis. This was possibly due to a larger biomass, and better quality, of the organic matter from that submersed specie, or to epiphytic biofilms on the living plants. Those microcosms studies showed that both the quality of the organic matter as a substrate for the microbial communities, and the amount of organic material produced were important for the denitrification capacity. In pilot scale wetlands, the composition of the plant community was also a more important factor for high nitrate removal than the differences in hydraulic loads (equivalent of 1 or 3 d retention time), despite the cold climate. The greatest removal was found in wetlands with emergent vegetation dominated by P. australis and G. maxima, rather than in wetlands with submersed vegetation. In brief, the results presented in this thesis emphasize the importance of dense emergent vegetation for high annual nitrate removal in treatment wetlands.

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36

Wójcik, Weronika. "Evaluation of microbiological activity during the deammonification process for nitrogen removal". Thesis, KTH, VA-teknik, Vatten, Avlopp och Avfall, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96300.

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This master thesis is based on own studies. A four-month study was performed at Hammarby Sjostad Research Station, which is located in Stockholm. One-stage deammonification process was evaluated in two different system configurations in pilot plant scale. The theoretical background for this thesis works is presented in the first part and where is presented negative impacts of nitrogen compounds in environment and requirements for purified wastewater in European Union (Sweden and Poland). In the next part of the thesis the nitrogen cycle is described and with focus on biological reactions for nitrogen removal. Especially, nitrification/denitrification and anammox processes are described with special focus on parameters affecting the anammox process performance and its advantages and disadvantages of using this process. Experimental results from the four-month study and evaluation of the microbial activity are described in the last part.

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37

Bastviken, Sofia. "Nitrogen removal in treatment wetlands : factors influencing spatial and temporal variations /". Linköping : Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7564.

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Hallin, Sara. "Dynamics of denitrifying populations in activated sludge processes with nitrogen removal /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5539-1.gif.

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Chen, Wen. "A membrane bioreactor(MBR) for an innovative biological nitrogen removal process". Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557959.

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40

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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41

Hanson, Carter Curtis. "Temporal effect on nitrogen removal in a subsurface flow constructed wetland". Virtual Press, 1996. http://liblink.bsu.edu/uhtbin/catkey/1027117.

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A subsurface flow constructed wetland planted with the common reed (Phragmites australis) and softstem bulrush (Scirpus validus) was built in East Central Indiana. The objective of this study was to determine if temperature had an effect on nitrogen (N) removal from the wetland. The research was conducted from the first week of October 3, 1995 to the first week in December 5, 1995 why the wetland froze. Water samples were taken from 5 samplings sites in the system. Each sample was analyzed for organic-N, ammonia, nitrate, and total-N. In the system statistically significant amounts of organic-N, nitrate, and total-N were removed. Ammonia lever reductions, however, were not significant. Organic-N had a mean removal of 37% (8 mg/1) 'Nitrate had a mean removal of 96% (2.3 mg/1). Total-N removal over the sampling period averaged 30% (12 mg/1). The N results were regressed against air and wastewater temperatures. Wastewater temperature was more important because it had a direct impact can the plants and microbes in the system. Warmer temperatures sustained a higher metabolism for the biota in the system. Air temperature had an indirect impact on efficiency of N removal from the wastewater flowing through the wetland. The primary impact .: f the air temperature was on water temperature which then affected the metabolism of or a nc ns in the wetland cell. Greater removal efficiencies were seen during high temperature periods and lower removal efficiencies were noted when the temperatures were low.
Department of Natural Resources and Environmental Management

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42

Matheson, Fleur Elizabeth. "Nitrogen removal and the fate of nitrate in riparian buffer zones". Thesis, Durham University, 2001. http://etheses.dur.ac.uk/3810/.

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Riparian buffer zones, adjacent to waterways, may protect water quality by intercepting and removing nitrogen in runoff from agricultural land. This research comprised four parts: (1) a field study of nitrogen buffering by differently vegetated riparian zones in a United Kingdom (UK) sheep-grazed pastoral catchment; (2) a field study of surface and subsurface runoff hydrology, and nitrogen flux, in a UK riparian wetland; (3) a laboratory study ((^15)N tracer-isotope dilution) of microbial inorganic nitrogen production and removal processes in the UK riparian wetland soil; and (4) a laboratory microcosm study ((^15)tracer) of nitrate removal processes in bare and plant-inhabited (Glyceria declinata) New Zealand (NZ) riparian wetland soil. Dissolved organic nitrogen and ammonium were generally more important components of subsurface runoff than nitrate in the three UK riparian zones. All riparian zones were poor buffers having minimal effect on the nitrogen concentration of subsurface runoff. In the UK riparian wetland site subsurface (saturated zone) and surface 'preferential flow paths' typically conveyed large quantities of catchment runoff rapidly into, and across the site, and hindered nitrogen buffering. However, under low flow conditions, runoff-riparian soil contact increased and the wetland decreased the catchment nitrogen flux by 27%. In the UK riparian wetland soil most nitrate removal was attributable to denitrification (87- 100%) as opposed to dissimilatory nitrate reduction to ammonium (DNRA) (0-13%) and immobilisation (0-10%). Total ((^14)N+(^15)N) transformation rates for these processes were 1.3-47, 0.5-1.5 and 0.6-2.5 μg N g soil(^-1) hr(^-1) respectively. In the NZ riparian wetland soil Glyceria declinata assimilated 11-15% of nitrate but, more importantly, increased soil oxidation and altered the proportions of nitrate removal attributable to denitrification (from 29% to 61-63%) and DNRA (from 49 to <1%), but not immobilisation (22-26%). Denitrification and, thus, nitrogen buffering might be enhanced, in some riparian zones by increasing the extent of moderately anoxic soil with plants that release oxygen from their roots or with water table management.

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Brooker, Michael R. "The Wetland Dilemma: Nitrogen Removal at the Expense of Methane Generation". The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376418382.

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Clayton, John Andrew. "Denitrification kinetics in biological nitrogen and phosphorus removal activated sludge systems". Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/21139.

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In order to size the anoxic reactors in nutrient (N and P) removal activated sludge plants, it is essential to know the denitrification kinetics that are operative in such systems. To date, denitrification kinetics have been accurately defined only for systems that remove N alone; little research has been performed on denitrification in N and P removal plants.

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45

Chui, Peng-Cheong. "STUDY ON ORGANICS AND NITROGEN REMOVAL USING SUBMERGED FIXED-BED FILTERS". Kyoto University, 1999. http://hdl.handle.net/2433/181847.

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46

Legwaila, Gabatshele Mbona. "Effects of panicle removal and nitrogen on yield of grain sorghum". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06162009-063221/.

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47

Gihring, Thomas M. "Direct determination of nitrogen removal rates and pathways in coastal ecosystems". Tallahassee, Florida : Florida State University, 2009. http://etd.lib.fsu.edu/theses/available/etd-05082009-110340/.

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Thesis (Ph. D.)--Florida State University, 2009.
Advisor: Joel Kostka, Florida State University, College of Arts and Sciences, Dept. of Oceanography. Title and description from dissertation home page (viewed on Oct. 5, 2009). Document formatted into pages; contains xiv, 142 pages. Includes bibliographical references.

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48

Robiglio, Alessio. "Nitrogen removal from municipal wastewater by mainstream Partial Nitritation/Anammox process". Thesis, KTH, Vatten- och miljöteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235919.

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Mainstream Partial Nitritation/Anammox, also known as Mainstream Deammonification, is a promising technology for future wastewater purification that aims to remove nitrogen from wastewater in order to prevent the eutrophication. It is less costly than the traditional nitrification/denitrification process and it heads towards the direction of converting the WWTPs from energy consuming into energy producing facilities. This Master’s thesis is based on a study regarding the nitrogen removal from mainstream wastewater. It was conducted at Hammarby Sjöstadsverk that is a research facility in the area of the Henriksdal Waste Wastewater Treatment Plant in Stockholm. Three parts of the study were developed. The main one had the purpose to evaluate the process performances of a biological pilot-scale IFAS reactor used for Mainstream Deammonification that was operated from October 2017 to March 2018. This evaluation was addressed to comprehend how the pilot-scale reactor works at different operational conditions. The remaining studies analysed the progress of the pilot-scale reactor in relation to different factors and to the settling properties of the activated sludge used in the process. It was found that the process performances improved by changing the aeration pattern from 40 to 50 minutes for non-aeration time and from 20 to 10 minutes for aeration time and by increasing the dissolved oxygen set-point from 0.6 to 1.0 mg/L. The enhancement of the performances consisted in an inhibition of nitrite oxidizing bacteria and rise of the total nitrogen removal efficiency. In addition, anammox biofilm was observed to grow on the carriers and it was observed that the activated sludge did not have good settling properties.

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Redmond, Eric. "Nitrogen removal from wastewater by an aerated subsurface flow constructed wetland". Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/2971.

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The purpose of this research was to assess the ability of subsurface flow wetlands, with aeration and vegetation, to remove nitrogen in cold weather climates. Aeration was shown to enhance the wetland cell's ability to remove not only nitrogen but also CBOD, COD, and phosphorus (retention) more effectively. There was a significant difference (p< 0.05) in both total nitrogen and ammonia effluent concentrations comparing aerated to unaerated wetland cells, while no significance was found comparing planted and unplanted wetland cells. The effluent ammonia concentrations from the aerated wetland cells ranged from 2.7 to 5.7 mg N/L, while for unaerated cells effluent concentration ranged from 22 to 23 mg N/L. The effluent total nitrogen concentrations from the aerated wetland cells ranged from 9.0 to 12 mg N/L, while those from unaerated cells ranged from 23 to 24 mg N/L. The effluent concentrations showed no significant difference (p < 0.05) when comparing results of three temperature ranges. There is a correlation when comparing ammonia mass removal rates to mass loading rates. Ammonia removal in the aerated wetland cells ranged from 82 to 95%, while unaerated cells ranged from 39 to 45%. The hydraulic retention times ranged from 3.13 to 4.33 days and the tanks-in-series ranged from 1.46 to 2.84. Using this information the wetland cells were modeled using both the TIS and the PkC* models. The k values (PkC* model) of the aerated wetlands for ammonia ranged from 131 to 221 m/d, while the unaerated wetland cells had values ranging from 20.4 to 36.7 m/d. The models appear to show a good prediction of the effluent ammonia concentration for the unaerated cells but the aerated cells show the model does not effectively capture the effects of aeration.

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Berge, Nicole. "IN-SITU AMMONIA REMOVAL OF LEACHATE FROM BIOREACTOR LANDFILLS". Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3281.

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A new and promising trend in solid waste management is to operate the landfill as a bioreactor. Bioreactor landfills are controlled systems in which moisture addition and/or air injection are used as enhancements to create a solid waste environment capable of actively degrading the biodegradable organic fraction of the waste. Although there are many advantages associated with bioreactor landfills, some challenges remain. One such challenge is the ammonia-nitrogen concentration found in the leachate. The concentrations of ammonia-nitrogen tend to increase beyond concentrations found in leachate from conventional landfills because recirculating leachate increases the rate of ammonification and results in accumulation of higher levels of ammonia-nitrogen concentrations, even after the organic fraction of the waste is stabilized. Because ammonia-nitrogen persists even after the organic fraction of the waste is stabilized, and because of its toxic nature, it is likely that ammonia-nitrogen will determine when the landfill is biologically stable and when post-closure monitoring may end. Thus an understanding of the fate of nitrogen in bioreactor landfills is critical to a successful and economic operation. Ammonia-nitrogen is typically removed from leachate outside of the landfill. However, additional costs are associated with ex-situ treatment of ammonia, as separate treatment units on site must be maintained or the leachate must be pumped to a publicly owned wastewater treatment facility. Therefore, the development of an in-situ nitrogen removal technique would be an attractive alternative. Several recent in-situ treatment approaches have been explored, but lacked the information necessary for field-scale implementation. The objectives of this study were to develop information necessary to implement in-situ ammonia removal at the field-scale. Research was conducted to evaluate the kinetics of in-situ ammonia removal and to subsequently develop guidance for field-scale implementation. An aerobic reactor and microcosms containing digested municipal solid waste were operated and parameters were measured to determine nitrification kinetics under conditions likely found in bioreactor landfills. The environmental conditions evaluated include: ammonia concentration (500 and 1000mg N/L), temperature (25o, 35o and 45oC), and oxygen concentration in the gas-phase (5, 17 and 100%). Results suggest that in-situ nitrification is feasible and that the potential for simultaneous nitrification and denitrification in field-scale bioreactor landfills is significant due to the presence of both aerobic and anoxic areas. All rate data were fitted to the Monod equation, resulting in an equation that describes the impact of pH, oxygen concentration, ammonia concentration, and temperature on ammonia removal. In order to provide design information for a field-scale study, a simple mass balance model was constructed in FORTRAN to forecast the fate of ammonia injected into a nitrifying portion of a landfill. Based on model results, an economic analysis of the in-situ treatment method was conducted and compared to current ex-situ leachate treatment costs. In-situ nitrification is a cost effective method for removing ammonia-nitrogen when employed in older waste environments. Compared to reported on-site treatment costs, the costs associated with the in-situ ammonia removal process fall within and are on the lower end of the range found in the literature. When compared to treating the leachate off-site, the costs of the in-situ ammonia removal process are always significantly lower. Validation of the laboratory results with a field-scale study is needed.
Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engineering

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