Vita. / Digitized by Kansas Correctional Industries

Effective control of nitrification processes employed at municipal wastewater treatment plants is essential for maintaining process reliability and minimizing environmental impacts and operating costs. While a range of process control strategies are available, they share a dependence on invasive liquid phase monitoring and are based on a periphery understanding of the metabolic status of the processes being controlled. Utilization of off-gas nitrous oxide (N2O) monitoring as a real-time indicator of the process metabolic status is a novel process control concept with the potential to address these concerns. This thesis details the development and evaluation of an off-gas N2O stress response based control technique. Examination of the stress response relationship demonstrated that it met the majority of the criteria of interest for process control. A simple feedback aeration control strategy was developed and evaluated through process simulation to determine the feasibility of implementation, cost effectiveness and associated environmental benefits. The off-gas N2O based control strategy provided better matching between aeration supply and metabolic demand, allowing the process to be maintained at the desired operating setpoints and avert nitrification failure. Performance was demonstrated to be similar to dissolved oxygen based feedback aeration control, although slightly more efficient at reduced dissolved oxygen concentrations. A technical, economic and environmental evaluation indicated that aeration control based on non-invasive off-gas N2O monitoring is technically feasible and has the potential to offer significant environmental and economic benefits including reductions in operating costs and process capital investment, as well as improved effluent compliance and reductions in emissions of gaseous pollutants including greenhouse gases. Overall, while off-gas N2O monitoring based aeration control techniques have the potential to provide significant economic and environmental benefits, a number of research questions remain to be answered. Future work in the form of long-term field trials is required to address these issues and allow quantification of economic and environmental benefits.

Bibliography: leaves 183-202

This thesis describes a laboratory investigation of in-situ treatment of synthetic leachate representative of that generated by a municipal solid waste (MSW) landfill. The overall objective is to evaluate alternative designs and operating procedures for effective leachate collection in conjunction with efforts to accelerate waste stabilization (i.e. leachate recirculation). In the investigation five 15 cm (6) diameter PVC columns were packed with pea gravel and concrete of different sizes; geotextiles were also placed between the packed sections as filter-separators and promoters of bacterial growth. Synthetic leachate was continuously input to the top of the columns and circulated at rates representative of operating field conditions. For each column, effluent was discharged to a nitrification reactor before recirculation. The tests were conducted under anaerobic and unsaturated conditions in the columns. Results indicate about a 97% decrease in COD from the synthetic leachate concentration entering the top of the column, and about 98 % conversion of the ammonia to nitrogen gas. COD depletion and methane production were not significantly inhibited by the denitrification process. Optimum Hydraulic Retention Time (HRT) for the nitrification-denitrification system makes it economically viable for its development at a landfill site. Gas production shows low CO2 values, decreasing the potential of clogging in the Leachate Collection System (LCS) and extending the Landfill Gas (LFG) networks life service by generating a less corrosive environment. The use of concrete as an alternative to the most commonly used natural gravel as leachate collection drains may not be a good option. During the experiment, the leachate that permeated the columns packed with crushed concrete, presented a higher pH than the leachate that permeated the natural stone. At the conclusion of the experiment noticeable weathering was observed when the columns where dismantled. Further studies are recommended until more conclusive evidence as to concrete performance is found. The overall results obtained from the experiment show that in situ passive treatment at landfills is viable.

Intensive swine operations produce large amounts of manure that must be dealt with responsibly. Liquid swine manure (LSM) collected in storage units is applied to cropland as a nutrient source. Maximizing crop utilization of the nitrogen (N) added in manure is important to achieve economic and environmental benefits. The objectives of this research were to evaluate the effect of 1) adding a nitrification inhibitor and 2) using supplemental phosphorus (P) and sulfur (S) fertilizers as means of enhancing crop recovery of LSM-N.<p>Field experiments were conducted at two long-term manure management sites in Saskatchewan; 1) Dixon (Black Chernozem) and 2) Melfort (Dark Grey Luvisol). At the Dixon site, plant and soil samples were collected throughout the 2005 and 2006 growing season, and ammonium-N (NH4+-N) and nitrate-N (NO3--N) concentration in soil, and total N content in plant were measured. Plant root simulator (PRSTM) probes were used to measure NH4+-N and NO3--N supply rates at the Dixon site to determine the effectiveness of a nitrification inhibitor dicyandiamide (DCD) added to LSM. Crop recovery of N applied through LSM application was assessed by measuring seed and straw yield and total N content. The effect of adding supplemental P fertilizer at 6.5 kg P ha-1 to swine manure amended soil on N recovery was also evaluated at the Dixon site. At the S deficient Melfort site, the effect of supplemental S fertilizer added at 40 kg S ha-1 as ammonium sulfate and elemental S was evaluated.<p>The addition of DCD (0.275 mL kg-1) to LSM in 2005 and 2006 at Dixon did not significantly affect the proportion of LSM-N recovered or the seed yield. However, measurements of available NH4+-N and NO3--N concentrations and supply rates at the beginning of the growing season in 2005 indicated that the nitrification inhibitor was effective in keeping more of the LSM-N in the NH4+ form for approximately 14 days after LSM application. <p> The addition of supplemental P fertilizer to plots fertilized with LSM at the Dixon site, generally did not produce any significant increase in crop N recovery or seed yield. However, increase in crop N recovery and seed yield in 100 kg N ha-1 urea treatments indicates that there was insufficient P available in the soils to maximize crop N recovery and seed yield. It appears that LSM is able to provide sufficient amounts of available P when applied annually at rates of 37,000 L ha-1 or higher. <p>At the Melfort site, the addition of supplemental S fertilizer did not significantly affect crop N recovery or seed yield in LSM treatments. Annual applications of the low rate of LSM of 37,000 L ha-1 supplied sufficient amounts of N and S to maximize seed yield and crop N recovery. However, large significant increases in seed yield and crop N recovery with supplemental S fertilizers were observed in the 80 kg N ha-1 urea treatment.<p>The use of a nitrification inhibitor added to LSM was effective at maintaining N in NH4+ form longer; however there was no significant effect on final yield, grain N or %N recovery. This may be due to the low N loss potential on prairies. Supplemental S and P fertilizer may be required with liquid swine manure. Supplemental commercial fertilizers with LSM are dependant on: the crop nutrient requirements, soil nutrient status and manure nutrient composition.

El tema d'estudi d'aquesta tesi és l'eliminació biològica de nitrogen d'aigües amb alta càrrega d'amoníac, més concretament, el procés de nitrificació (l'oxidació de l'amoni a nitrat). Aquesta reacció en dos passos, catalitzada per dos tipus de microorganismes (AOB i NOB), pot patir problemes d'inhibicions per amoníac i àcid nitrós. Això és especialment important quan es tracta aigua amb alta concentració d'amoni i per tant, es necessita un control del procés adequat. Tot i així, aquestes inhibicions es poden utilitzar per a aconseguir nitrificació parcial (l'oxidació de l'amoni a nitrit), la qual combinada amb el procés de desnitrificació, aporta beneficis importants pel què fa a la utilització dels recursos.En aquesta tesi es mostra el desenvolupament i calibratge d'un model matemàtic per a descriure la cinètica i l'estequiometria de la nitrificació considerant les inhibicions mencionades anteriorment i tenint en compte els dos tipus de bacteris nitrificants i també els bacteris heteròtrofs. Es varen dissenyar experiments específics per a l'optimització dels paràmetres del model i amb l'ajuda d'eines d'identificabilitat de paràmetres, aquests experiments es van analitzar i millorar. Les constants d'afinitat pel substrat i els coeficients d'inhibició per substrat es van determinar dues vegades utilitzant biomasses diferents i es van obtenir resultats diferents. Això indicà que aquests paràmetres són variables i depenen de l'aclimatació de la biomassa. Es va utilitzar la tècnica d'hibridació fluorescent in situ (FISH) per a la detecció i quantificació de les fraccions bacterianes. Per a la detecció de la fluorescència es van utilitzar un microscopi d'epifluorescència, un microscopi confocal i un citòmetre de flux. Els resultats obtinguts es van comparar entre ells i es van discutir els seus avantatges i inconvenients tenint en compte la precisió dels resultats, la velocitat de l'anàlisi i la disponibilitat de l'equip. La millor metodologia va resultar ser l'observació del FISH amb el microscopi confocal encara que la citometria de flux no es va poder investigar prou a fons. El model matemàtic desenvolupat i calibrat en aquesta tesi es va utilitzar per a l'optimització de la posada en marxa d'un sistema de nitrificació completa. Es van optimitzar dues estratègies de control que posteriorment es van implementar experimentalment partint d'un inòcul procedent dels llots d'una estació de tractament d'aigües residuals urbanes. El controlador dissenyat es basava en la mesura de la velocitat del consum d'oxigen (OUR) en l'últim reactor del sistema i actuava sobre la càrrega d'entrada. Els resultats obtinguts es van comparar amb els resultats d'una posada en marxa amb control manual i es va demostrar que el control automàtic permet disminuir el temps de posada en marxa i augmentar l'estabilitat del procés. Posteriorment, els resultats experimentals es van simular amb el model matemàtic obtenint un bon ajust. Finalment, el nou model es va utilitzar per a fer prediccions del comportament del sistema a curt i llarg termini. L'enriquiment de la biomassa en microorganismes nitrificants es va comprovar mitjançant el FISH i la microscòpia confocal. La biomassa que es va obtenir després de la última posada en marxa del sistema es va utilitzar per a aconseguir la nitrificació parcial treballant a 25 ºC, 1.1 mg O2 L-1, pH de 8.3 i amb un set point d'OUR apropiat en el control automàtic. La nitrificació parcial es va mantenir de forma estable durant uns 120 dies amb una càrrega mitjana de 0.5 g N g-1 SSV d-1. L'anàlisi microbiològic amb FISH va demostrar que la població de NOB havia estat eliminada del sistema. Posteriorment, el sistema de control es va millorar amb l'adició de dues regles de control expert que van permetre l'operació estable del sistema davant d'importants pertorbacions externes. / Biological nitrogen removal of high-strength ammonium wastewater was studied in this thesis, particularly, the nitrification process (the oxidation of ammonium to nitrate). This two-step reaction, catalyzed by two kinds of bacteria (AOB and NOB), can suffer serious inhibition problems due to ammonia and nitrous acid when dealing with highly concentrated ammonium wastewater and therefore it requires adequate process control. However, these inhibitions can be used to achieve partial nitrification (the oxidation of ammonium to nitrite), which coupled to a denitrifying process leads to significant benefits in terms of use of resources.A mathematical model describing the kinetics and the stoichiometry of the nitrification process was developed and calibrated. It considered the aforementioned inhibitions and took into account both kinds of nitrifying bacteria and also heterotrophic bacteria. Specific experiments were designed for parameter estimation and parameter identifiability tools were used to analyze and improve them. Optimal experimental designs were used to calibrate most of the model parameters and the obtained values were compared with values found in the literature. Affinity constants for substrate and substrate inhibition coefficients were estimated twice using different sludges and, as a result, different values were found indicating that they change depending on the biomass acclimation. This model was coupled to the hydraulic model of the experimental system (pilot plant) and was implemented in Matlab ®. Fluorescence in situ hybridization (FISH) was used for bacterial fractions detection and quantification. Several equipments were used for fluorescence detection: an epifluorescence microscope, a confocal microscope and a flow cytometer. Biomass fractions were determined with each of the equipment and also with simulations. Obtained results were compared and the advantages and disadvantages of the tested methodologies were discussed considering the accuracy of the results, the speed of the analysis and the availability of the equipment. FISH combined with confocal microscopy turned out to be the best technique for nitrifying biomass quantification although flow cytometry could not be extensively investigated.The start-up of a complete nitrification system was optimized by means of mathematical simulation using the previously developed and calibrated method. Two automatic control strategies were optimized and implemented in the experimental system by using sludge from a municipal wastewater treatment plant as inoculum. The controller was based on the measurement of the oxygen uptake rate (OUR) in the last reactor of the system and actuated over the nitrogen loading rate. Results were compared with a start-up performed with manual control and it was demonstrated that automatic control decreased the length of the start-up and increased its stability. Then, experimental results were simulated with the nitrification model. Model predictions agreed well with experimental data. The final model was useful for both long- and short-term prediction. The sludge enrichment in nitrifying bacteria was checked with FISH and confocal microcopy.The nitrifying sludge obtained after the last start-up contained both AOB an NOB and was used to achieve partial nitrification. Some environmental conditions and the automatic control strategy were changed in order to inhibit NOB and wash them out of the system. Partial nitrification with an effluent devoid of nitrate was achieved at 25 ºC, 1.1 mg O2 L-1 and pH of 8.3 using the appropriate OUR set point for the automatic controller. Partial nitrification was run for 120 days with an averaged nitrogen loading rate of 0.5 g N g-1 VSS d-1. FISH analysis demonstrated that NOB were completely washed out. The control strategy was improved by the addition of two expert rules and stable operation was maintained even when external disturbances were provoked. Finally, a model-based study was performed to test the partial nitrification start-up strategy under different conditions and system configurations.

MELiSSA (Micro Ecological Life Support System Alternative) és el sistema desenvolupat per l'Agència Espacial Europea (ESA) i el consorci MELiSSA en el camp del suport de vida durant missions de llarga durada a l'espai. Basat en un ecosistema aquàtic, MELiSSA va ser concebut com una eina per desenvolupar la tecnologia necessària per a un sistema de suport de vida biològic que en un futur ha de permetre la producció d'aliment, aigua i oxigen a partir dels residus orgànics generats per una tripulació. Per assolir aquest objectiu, el concepte MELiSSA compta amb l'activitat combinada de cinc compartiments colonitzats per diferents microorganismes i plantes superiors, interconnectats entre ells. Aquesta tesi es centra en el tercer compartiment del bucle MELiSSA, en el qual l'amoni és convertit a nitrat, que és la font de nitrogen més adequada per al creixement dels cianobacteris i plantes superiors que colonitzen els compartiments fotosintètics. L'oxidació biològica d'amoni a nitrat té lloc en dues etapes successives que porten a terme dos tipus de soques bacterianes. En el projecte MELiSSA aquest procés es porta a terme en una columna de llit fix mitjançant Nitrosomonas europaea i Nitrobacter winogradkyi immobilitzats sobre un suport polimèric, i amb aportació d'aire en el mateix sentit de circulació que el medi líquid. El reactor pilot del tercer compartiment ha estat operant a la planta pilot del projecte MELiSSA durant períodes prolongats de temps abans de l'inici del treball realitzat en aquesta tesi. La principal aportació d'aquesta tesi es troba en l'obtenció de nova informació sobre el funcionament del reactor a través d'un estudi detallat de la biopel·lícula i també mitjançant el desenvolupament d'un model matemàtic que ens permetrà estudiar els efectes de diferents paràmetres d'operació sobre el procés i l'estructura de la biopel·lícula. S'implementaran també els aparells de mesura necessaris per millorar la qualitat de la monitorització de les diferents espècies de nitrogen a la fase líquida. Els coneixements adquirits en la realització d'aquest treball seran utilitzats per portar a terme el re-disseny del reactor per tal de millorar-ne el funcionament dins de la planta pilot del projecte MELiSSA. / MELiSSA (Micro Ecological Life Support System Alternative) is the system developed by the European Space Agency (ESA) and the MELiSSA consortium in the field of life support for long term manned missions in Space. Based on the principle of an aquatic ecosystem, MELiSSA was conceived as a tool to develop the required technology for a future biological life support system. Its final aim is the production of food, fresh water and oxygen from the organic wastes of a crew. To achieve this goal, the MELiSSA concept is based on the use of five interconnected compartments colonised by several microorganisms and higher plants. This thesis is focused on the third compartment of the MELiSSA loop, in which ammonium is converted to nitrate, the most suitable nitrogen source for the growth of the bacteria and higher plants colonising the photosynthetic compartment. The biological oxidation of ammonium to nitrate, which consists of two successive reactions carried out by two different bacterial strains, takes place in a packed bed biofilm reactor. Nitrosomonas europaea and Nitrobacter winogradskyi are immobilised on a polymeric support, with air flowing cocurrently with the feed medium. The pilot-scale reactor of compartment III (CIII) had been in operation in the MELiSSA pilot plant for several years before the start of the present work. The main contributions of this thesis are in increasing the understanding of the reactor performance by studying the nitrifying biofilm in depth, and by developing a mathematical model that allows the effects of different operational parameters on the process and on the biofilm structure, to be studied. Moreover, continuous monitoring of the nitrifying efficiency will be improved by installing the necessary on-line equipment to experimentally measure the concentrations of all the nitrogen species in the liquid phase. The additional knowledge achieved on the reactor performance via this work will finally lead to re-design the reactor hardware for optimal performance in the MELiSSA pilot plant. The knowledge acquired in this thesis was finally used to define the main features of the re-design of the pilot reactor of the MELiSSA compartment III.

This thesis describes a laboratory investigation of in-situ treatment of synthetic leachate representative of that generated by a municipal solid waste (MSW) landfill. The overall objective is to evaluate alternative designs and operating procedures for effective leachate collection in conjunction with efforts to accelerate waste stabilization (i.e. leachate recirculation). In the investigation five 15 cm (6) diameter PVC columns were packed with pea gravel and concrete of different sizes; geotextiles were also placed between the packed sections as filter-separators and promoters of bacterial growth. Synthetic leachate was continuously input to the top of the columns and circulated at rates representative of operating field conditions. For each column, effluent was discharged to a nitrification reactor before recirculation. The tests were conducted under anaerobic and unsaturated conditions in the columns. Results indicate about a 97% decrease in COD from the synthetic leachate concentration entering the top of the column, and about 98 % conversion of the ammonia to nitrogen gas. COD depletion and methane production were not significantly inhibited by the denitrification process. Optimum Hydraulic Retention Time (HRT) for the nitrification-denitrification system makes it economically viable for its development at a landfill site. Gas production shows low CO2 values, decreasing the potential of clogging in the Leachate Collection System (LCS) and extending the Landfill Gas (LFG) networks life service by generating a less corrosive environment. The use of concrete as an alternative to the most commonly used natural gravel as leachate collection drains may not be a good option. During the experiment, the leachate that permeated the columns packed with crushed concrete, presented a higher pH than the leachate that permeated the natural stone. At the conclusion of the experiment noticeable weathering was observed when the columns where dismantled. Further studies are recommended until more conclusive evidence as to concrete performance is found. The overall results obtained from the experiment show that in situ passive treatment at landfills is viable.

Intensive swine operations produce large amounts of manure that must be dealt with responsibly. Liquid swine manure (LSM) collected in storage units is applied to cropland as a nutrient source. Maximizing crop utilization of the nitrogen (N) added in manure is important to achieve economic and environmental benefits. The objectives of this research were to evaluate the effect of 1) adding a nitrification inhibitor and 2) using supplemental phosphorus (P) and sulfur (S) fertilizers as means of enhancing crop recovery of LSM-N.<p>Field experiments were conducted at two long-term manure management sites in Saskatchewan; 1) Dixon (Black Chernozem) and 2) Melfort (Dark Grey Luvisol). At the Dixon site, plant and soil samples were collected throughout the 2005 and 2006 growing season, and ammonium-N (NH4+-N) and nitrate-N (NO3--N) concentration in soil, and total N content in plant were measured. Plant root simulator (PRSTM) probes were used to measure NH4+-N and NO3--N supply rates at the Dixon site to determine the effectiveness of a nitrification inhibitor dicyandiamide (DCD) added to LSM. Crop recovery of N applied through LSM application was assessed by measuring seed and straw yield and total N content. The effect of adding supplemental P fertilizer at 6.5 kg P ha-1 to swine manure amended soil on N recovery was also evaluated at the Dixon site. At the S deficient Melfort site, the effect of supplemental S fertilizer added at 40 kg S ha-1 as ammonium sulfate and elemental S was evaluated.<p>The addition of DCD (0.275 mL kg-1) to LSM in 2005 and 2006 at Dixon did not significantly affect the proportion of LSM-N recovered or the seed yield. However, measurements of available NH4+-N and NO3--N concentrations and supply rates at the beginning of the growing season in 2005 indicated that the nitrification inhibitor was effective in keeping more of the LSM-N in the NH4+ form for approximately 14 days after LSM application. <p> The addition of supplemental P fertilizer to plots fertilized with LSM at the Dixon site, generally did not produce any significant increase in crop N recovery or seed yield. However, increase in crop N recovery and seed yield in 100 kg N ha-1 urea treatments indicates that there was insufficient P available in the soils to maximize crop N recovery and seed yield. It appears that LSM is able to provide sufficient amounts of available P when applied annually at rates of 37,000 L ha-1 or higher. <p>At the Melfort site, the addition of supplemental S fertilizer did not significantly affect crop N recovery or seed yield in LSM treatments. Annual applications of the low rate of LSM of 37,000 L ha-1 supplied sufficient amounts of N and S to maximize seed yield and crop N recovery. However, large significant increases in seed yield and crop N recovery with supplemental S fertilizers were observed in the 80 kg N ha-1 urea treatment.<p>The use of a nitrification inhibitor added to LSM was effective at maintaining N in NH4+ form longer; however there was no significant effect on final yield, grain N or %N recovery. This may be due to the low N loss potential on prairies. Supplemental S and P fertilizer may be required with liquid swine manure. Supplemental commercial fertilizers with LSM are dependant on: the crop nutrient requirements, soil nutrient status and manure nutrient composition.

Due to various components within the landfill sites, the water qualityof landfill leachate, which has high consistency of COD, BOD and nutrients, is unsteady. Using traditional sewage treatment plant to treat leachate should be designed and built to fit the unsteady water quality, which is usually time consuming and high expenditured. Therefore, application of constructed wetland treatment systems as altanatives may solve such kinds of problems According to the experimental results of this study, referring to the effect of cleaning the controlling substances, the SSF (sub-surface flow system) constructed wetland system performed better than the FWS (free-water surface system) one, which was because FWS was usually operated in an opening water areas, which exposured to the air causing stink in the inflow site of influent, and meanwhile caused problems of virus-transmitting mosquitoes. . Thus, it was suggested to use SSF system in treating landfill leachate. In this study, we found that the average removal efficiencies of pollutants in the leachate were high in the constructed wetland systmes (phosphate 73%, total phosphorous 70¢H, total nitrogen 57%, NH3-N 77¢H, COD 43% ). In addition, the BOD in the effluent from the systems could reach the outflow standard guideline in Taiwan (30 mg/L). Hence, using constructed wetland systems to solve those problems arisen from landfill leachate is expandable. We also found that the aquatic plant species of reed (Phragmites australis) that we used in this study could not grow well and was invaded by aphid due to the limitary environment in the landfill site and lack of biodiversity, which could not generate a good natural food chain. On the other hand, it was found that the plant species of evergreen (Dracaena sanderiana) could grow healthily and present high removal efficiencies for pollutants. Since the leachate was lack of biodegradable organic carbon sources used for denitrification, in the final test run of this study, we run an experiment of adding organic carbon sourcecs (fructose and molasses) into the constructed wetland systemis to test its effect on denitrification. The experimental results showed that the addition of organic carbon sources could significantly increase the efficiencies of denitrification to let more nitrate removed from the leachate, especially for molasses, which could increase the denitrification efficiency above 90%.