Three membrane bioreactors, a low flux filter (LFF), a diafilter (DF), and an ion-exchange (IE) membrane bioreactor were used to treat water polluted with 50 ppm-N nitrate. The three systems were compared in terms of removal efficiency of nitrate, operational complexity, and overall quality of the treated water. In the low flux filter (LFF) membrane bioreactor an hemo-dialysis hollow fiber module was used and operated continuously for 29 days with a constant flux of permeate. The performance of the system was constant during the span of the experiment, which demonstrated that when the module was operated under constant low flux of permeate, the membrane filtration process was not affected by fouling. The removal rate of the LFF was 100% since the treated effluent did not contain nitrate or nitrite. The volumetric denitrification rate was 240 g-N day-1 m-3, which is within the range of denitrification rates obtained in tubular membrane modules. The treated effluent contained acetate, the carbon source of the biological process, and other inorganic nutrients, which showed that operating this ultrafiltration module at controlled flux did not improve the retention of these substances in the bioreactor. The same hemo-dialysis hollow fiber module employed in the LFF system was used in the diafilter (DF) membrane bioreactor. In the DF system, however, the membrane module was used as a contactor that separated the treated water and the bioreactor system, which allowed the transfer of solutes through the membrane porous structure and supported the growth of a biofilm on the membrane surface. The nitrate removal rate of the DF system increased from 76% to 91% during the 17 days assay. Unfortunately, this improvement could be attributed to microbial contamination of the water circuit because significant concentrations of the carbon source, acetate, nutrients, and nitrate were found in the treated effluent. The volumetric denitrification rate of the system was 200 g-N day-1 m-3, and the surface denitrification rate was lower than values previously reported for contactor membrane bioreactors. The results hereby presented do not evidence any advantage of operating the Filtral 20 ® membrane module as a contactor instead of as a filter such as in the LFF system. On the other hand, the third system herein presented, the IE membrane bioreactor, demonstrated several advantages of a contactor configuration but with a non-porous ion exchange membrane module in place of the Filtral 20 ®. As in a contactor system, the anion membrane provided a surface for biofilm growth, facilitated the transport of nitrate, and prevented mixing of treated water and bioreactor medium. Compared to the two previous systems, the most remarkable result of the IE was the reduction of secondary pollution in the treated water. The concentrations of phosphate and ethanol were zero and less than 1% of the concentration in the bioreactor, respectively. In addition, the IE system was less complex than the two other systems because the ion exchange membrane is non-porous. Therefore, unlike with porous contactors, it was not necessary to control the flux of treated water that could be lost through the bioreactor. The average surface denitrification rate of the IE system was 7.0 g-N day-1 m-2, which is higher than what had been reported for other contactor denitrification systems. However, because of the low surface to volume ratio of the membrane module that was used, the volumetric denitrification rate of the IE system was low, equivalent to 65 g-N day-1 m-3. / Master of Science

Limitations in the quality of transformation rates used with water quality models such as QUAL2K have led to the need to identify methods that can effectively and accurately determine these rates. During the early stages of method development of a Utah Department of Environmental Quality (Utah DEQ) funded project seeking to identify such methods, it was determined that under certain situations external carbon amendment may be required to successfully determine denitrification rates. The focus of this study was to evaluate the potential impacts that introducing external carbon sources may have on estimating the laboratory denitrification rates resulting from these methods. Ultimately it was shown that, carbon amendment does not negatively impact the comparability of laboratory-generated rates to those that could be measured using in-situ methods. Additionally, it was determined that the Substrate Chemical Product method discussed herein should be used along with a no carbon, glucose, and sodium acetate amended treatments. After analysis of the data, the highest rate should be used if differences caused by carbon amendment can be identified.

Haloarchaea are extremophiles, generally thriving at high temperatures and salt concentrations, thus, with limited access to oxygen. As a strategy to maintain a respiratory metabolism, many halophilic archaea are capable of denitrification. Among them are members of the genus Haloferax, which are abundant in saline/hypersaline environments. Based on the haloarchaeal genomes analysed, the genes involved in denitrification are grouped into three gene clusters (nar, nir-nor, nos) coding for denitrification enzymes NarGHI, NirK, qNor and NosZ. In case of incomplete denitrifiers, some of the genes or clusters are absent. Amon all haloarchaea analysed, three reported denitrifiers, H. mediterranei, H. denitrificans and H. volcanii were characterized with respect to their denitrification phenotype using a semi-automatic incubation system. Out of the species tested, only H. mediterranei was able to consistently reduce all available N-oxyanions to N2, while the other two released significant amounts of NO and N2 O, which affect tropospheric and stratospheric chemistries respectively. Also, H. mediterranei showed a well-orchestrated system of gene expression during denitrification, being Nar and Nos, both transcriptionally activated by hypoxia (and probably nitrate), while Nir and Nor expression require the presence of nitric oxide (and possibly nitrite) as well as Nos. The prevalence and magnitude of hypersaline ecosystems are on the rise due to climate change and anthropogenic activity. Thus, the biology of halophilic denitrifiers is inherently interesting, due to their contribution to the global nitrogen cycle, and potential application in bioremediation.

No description available.

No description available.

The objective of this dissertation was to provide a controlled comparison of identical continuous flow BNR processes both with and without prefermentation in order to provide a stronger, more quantitative, technical basis for design engineers to evaluate the potential benefits of prefermentation to EBPR in treating domestic wastewater. In addition, the even less understood effect of prefermentation on denitrification kinetics and anoxic phosphorus (P) uptake was studied and quantified. Other aspects of BNR performance, which might change due to use of prefermentation, will also be addressed, including anaerobic stabilization. Potential benefits to BNR processes derived from prefermentation are compared and contrasted with the more well-known benefits of primary clarification. Finally, some biokinetic parameters necessary to successfully model both the activated sludge systems and the prefermenter were determined and compared for the prefermented versus the non-prefermented system. Important findings developed during the course of this dissertation regarding the impact of prefermentation upon the performance of activated sludge treatment systems are summarized below: • For a septic COD-limited (TCOD:TP < 40:1) wastewater, prefermentation was found to enhance EPBR by 27.7% at a statistical significance level of alpha=0.05 (95% confidence level). • For septic P-limited (TCOD:TP > 40:1) wastewaters, prefermentation was not found to improve EBPR at a statistical significance level of alpha=0.05 (95% confidence level). • The increased anaerobic P release and aerobic P uptakes due to prefermentation correlated with greater PHA formation and glycogen consumption during anaerobiosis of prefermented influent. • Improvements in biological P removal of septic, non-P limited wastewater occurred even when all additional VFA production exceeded VFA requirements using typical design criteria (e.g. 6 g VFA per 1 g P removal). • Prefermentation increased RBCOD content by an average of 28.8% and VFA content by an average of 18.8%, even for a septic domestic wastewater. • Prefermentation increased specific anoxic denitrification rates for both COD-limited (14.6%) and P-limited (5.4%) influent wastewaters. This increase was statistically significant at alpha=0.05 for COD-limited wastewater, but not for P-limited wastewater.

Hydrogen sulfide (H2S), a major odorous component emitted from construction and demolition debris landfills, has received increasing attention. Besides its unpleasant odor, long-term exposure to a very low concentration of H2S can cause a public health issue. Although cover materials such as soil and compost are recommended to be used routinely to control an odor problem from the landfills, the problem still remains. Autotrophic denitrification may have environmental applications including treatment of water, groundwater, wastewater or gaseous streams contaminated with sulfur and/or nitrogen compounds. However, there have been no studies reported in the literature on H2S removal using autotrophic denitrification from landfills. This study, therefore, investigated the application of autotrophic denitrification incorporated into landfill covers in order to evaluate the feasibility of controlling H2S emissions generated from landfills. Research was investigated by two techniques, microcosm and laboratory-scale column studies. The microcosm experiments were conducted to evaluate the kinetics of autotrophic denitrification in various cover materials with H2S-nitrate as electron donor-acceptor couple. Cover materials including soil, compost and sand were tested and nitrate was added. Based on the microcosm study results, the addition of nitrate into soil and compost can stimulate indigenous autotrophic denitrifying bacteria which are capable of H2S oxidation biologically under anoxic conditions. Results also demonstrated that some amount of H2S can be removed physically and chemically by soil or compost. There was no H2S removal observed in sand microcosms. Rapid H2S oxidation to sulfate was achieved, especially in soil. Zero-order kinetics described the H2S oxidation rate in soil and compost microcosms. The rates of sulfide oxidation under autotrophic denitrification in soil and compost were 2.57 mg H2S/d-g dry soil and 0.17 mg H2S/d-g dry compost, respectively. To further explore H2S removal in a landfill biocover, two sets of column experiments were run. The first set of columns contained seven cm of soil. The autotrophic column was prepared with 1.94 mg KNO3/g dry soil; an identical control column was prepared without nitrate. A gas stream was introduced to the columns with a H2S concentration of 930 ppm. The second set contained seven cm of soil, with both an autotrophic (0.499 mg KNO3/g dry soil) and a control column. Influent H2S concentration was 140 ppm for the second set. Column studies supported the results of microcosm studies; removal of H2S was observed in all columns due to the capacity for soil to absorb H2S, however autotrophic columns removed significantly more. The higher concentration of H2S resulted in partial oxidation to elemental sulfur, while sulfate was found at levels predicted by stoichiometric relationships at the lower concentration. H2S oxidation in the column with higher loading was found to follow zero-order kinetics. The rate of H2S oxidation was 0.46 mg H2S removed/d-g dry soil. Economic comparison of cover systems including autotrophic denitrification, soil amended with lime, fine concrete, and compost covers were analyzed. Based on a case-study landfill area of 0.04 km2, the estimated H2S emissions of 80,900 kg over the 15-year period and costs of active cover system components (ammonium nitrate fertilizer, lime, concrete and compost), autotrophic denitrification cover was determined to be the most cost-effective method for controlling H2S emissions from landfills.

Abstract Investigation of a Commercial Product (BiOWiSH­­TM) for Nitrogen Management Eva Lee BiOWiSH–Aqua, which has the capability of treating nitrogen from wastewater through bioaugmentation, is a commercial product consisting of a blend of microorganisms developed by BiOWiSH Technologies. A study of the treatment of nitrogen compounds (i.e. , , and ) using Biowish–Aqua was conducted using small scale experiments (flask experiments) and large scale experiments (column reactor experiments). In this work, column reactors were created to test Biowish–Aqua’s nitrogen treating capabilities by providing enough depth to simulate the dissolved oxygen gradient that can be observed in a pond. The results show that the optimal growth conditions for both ammonia assimilating and denitrifying bacteria are an anoxic environment with a carbon-to-nitrogen ratio of 2:1. Under this optimal growth environment, Biowish–Aqua was able to assimilate ammonia with a zero order k value of 3.06 ppm/day. Also, under the same conditions, Biowish–Aqua was able to eliminate nitrate ( ) and nitrite ( ) at a rate of 9.58 ppm/day and 5.64 ppm/day respectively. The experiments also suggested that with a C:N ratio of 2:1, Biowish–Aqua did not have an effect in slowing the hydrolysis of urea. Overall, this research suggests that the application of Biowish–Aqua is a feasible nitrogen removing strategy for wastewater with initial presence of ammonia and nitrate between 10 to 20 ppm. Keywords: Ammonia assimilation, Bioaugmentation, BiOWiSH, Denitrification

This study involved the use of soil and suspended growth microcosms to study the variation in groundwater denitrification rates using different substrates. Two gaseous substrates, carbon monoxide and methane, were studied and compared to a common liquid substrate, methanol. Denitrification with carbon monoxide as a substrate was achieved using an acclimated seed of mixed activated sludge and anaerobic digester sludge. Kinetic studies of denitrification using carbon monoxide suggested a strong substrate inhibition effect. The observed maximum denitrification velocity of 0.026 mg N/d-mg VSS occurred at a carbon monoxide partial pressure of 0.10 atmospheres (2.8 mg/ℓ). At higher carbon monoxide partial pressures, denitrification velocities decreased. The denitrification velocities at various carbon monoxide concentrations were described by a modified form of the Haldane substrate inhibition model. The biomass yield using carbon monoxide was 1.1 mg VSS/mg VSS, the maximum specific growth rate was 0.03 mg VSS/d-mg VSS, and the half velocity constant was 26 mg-N/ℓ. Denitrification rates using carbon monoxide as a substrate were much slower than those obtained using methanol, and the cost of carbon monoxide was much higher. Denitrification occurred readily, when methanol was provided as a substrate, in microcosms containing either a clay soil, a sandy soil, or activated sludge. Under the conditions of this study, denitrification was not achieved in clay soil or sandy soil microcosms using methane or carbon monoxide as substrates. Denitrification was not achieved using methane as a substrate with an activated sludge seed. / Ph. D.

Accurately measuring denitrification in stochastic floodplains, particularly the leveed and unleveed reaches of the Mississippi River basin, requires innovative experiments. To replicate hydraulic variability ranging from overland flooding to groundwater exfiltration in floodplain wetlands, I incubated sediment cores collected from four field sites across the Dogtooth Bend of the middle Mississippi River; pairing novel deep injection (Graphic Abstract Fig. A, left) with traditional surface delivery (Graphic Abstract Fig. A, right) of both oxic and anoxic Mississippi River water. In sandy sediments with unconstrained flux of nutrients, denitrification more than doubled across a range from 192 to 429 mg N m-2 day-1 in a linear anoxic-injection hierarchy of anoxic deep > anoxic surface > oxic deep > oxic surface treatments. In contrast, for incubations in diffusion-limited clay sediments, injection type made no difference; however, in anoxic conditions denitrification rates were as high as 435 mg N m-2 day-1 compared to oxic incubations at 187 mg N m-2 day-1. This methodology reveals the magnitude of diverse denitrification rates spanning different hydrologic conditions (Abstract Fig. B) and the mediation of denitrification by sediment type. These findings provide quantified bounds to inform resource management decisions regarding what areas should be selected for protection or hydrologic reconnection to best facilitate nutrient processing services like denitrification under varying hydrologic conditions.