Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 99-112). Also available on the World Wide Web.

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on May 22, 2009. Major professor: Nirupam Pal, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Civil and Environmental Engineering." "March 2009." Includes bibliographical references (p. 88-90). Also available on microfiche.

Thesis (Ph.D.)--Washington State University, December 2005. / Includes bibliographical references.

Inaug.-diss.--Heidelberg. / Lebenslauf. "Literatur": p. [98]-100.

There is an increasing need for tertiary level wastewater treatment in Canada, driven in some cases by both provincial and federal regulation (Canada Gazette, 2012). Tertiary nitrification is the biologically mediated oxidation of nitrogen in the form of ammonia to nitrate following secondary treatment of carbonaceous material (Barnes & Bliss, 1983). The application of tertiary nitrification can prove challenging in the Canadian climate because of the temperature sensitive nature of nitrifiers (Hwang & Oleszkiewicz, 2007). Hence the greater than 1000 lagoon treatment plants currently in operation throughout country are susceptible to the full onslaught of weather effects and as such their nitrification processes become non-existent during the winter months (Delatolla et al., 2011,Hoang et al., 2014). The moving bed biofilm reactor (MBBR) system has been studied and shows promise for continuous nitrification with prolonged exposure to cold temperatures (Hoang et al., 2014). They are marketed as cost effective and low operation intensive upgrade options for existing treatment plants as well as effective stand-alone systems and are currently in operation in many countries worldwide (WEF, 2011). Despite the MBBRs initial development as a nitrification technology, recent research has been focused on COD removal systems. Studies showing that MBBR performance is directly related to surface area loading rates (SALRs) and not carrier type or shape have been performed exclusively on COD removal systems. The influence of MBBR carrier type on system solids production has also been solely studied for COD removal and the principles learnt have been transferred to tertiary nitrification systems without confirmation that they hold true. There is an absence of research on tertiary nitrifying kinetics; the effect of loading and carrier type, the nature of the solids produced and the carrier biofilm characteristics. This study investigated three MBBR carrier types, the K3, M and P Anoxkaldnes carriers in an effort to quantify the effects of carrier type on nitrifying kinetics, biologically – produced solids and the bacterial community at normal and high loading conditions. Four tertiary nitrifying laboratory scale MBBRs were fed with synthetic wastewater and operated at a high loading condition (HLC) with a SALR of 1.89 ± 0.10 g-N/m2•d and a normal loading condition (NLC) with SALR of 0.91 ± 0.1 g-N/m2•d. At both HLC and NLC, results show no difference in the ammonia removal rates obtained by the different carrier types. It was however noticed that stressed operational conditions developed for the P and M carrier at the HLC due to the clogging of carrier pore spaces with biofilm and subsequent reductions in removal efficiency were observed. Despite the fact that larger surface area to volume carriers (such as the M and P) may lead to MBBR designs with smaller footprints and lower operational cost, the study revealed their greater propensity to become clogged under high loading conditions than the smaller surface area carriers (such as the K3 ). In addition the larger surface area carriers demonstrated longer transitional periods from high loading conditions to lower loading conditions. A reduction in effluent total suspended solids (TSS) concentrations and improved solids settleability was observed with the shift from HLC to NLC. These results suggest the avoidance of high loading conditions in tertiary nitrifying MBBR operation. If low loading rates are not achievable then system design may have to consider the incorporation of coagulant use or an advanced solids separation technique to meet effluent solids regulation. Variable pressure scanning electron microscope (VPSEM) images at HLC showed the presence of water mites on the K3 carrier and nematodes and ciliates on the M and P carriers. While NLC images do not show these organisms. VPSEM also measured thicker biofilms during the HLC than the NLC for all carriers. The results demonstrate a difference in the meso-environments and suggest a difference in the micro-environments of the biofilm attached to each carrier. Microbial analysis showed no shifts in the dominant nitrifying species between the loading conditions, as well as no differences in the percent live /dead cell coverage. Nitrosomonas and Nitrospira were identified as the dominant AOB and NOB genera respectively at both the HLC and the NLC. Clear shifts in the microbial populations were observed for specific bacteria; with filamentous bacteria being observed at greater relative abundance at HLC than HLC. The increased relative abundance of filamentous organisms are also associated with the significantly poorer effluent settling characteristics observed at HLC.

Monod-type kinetic models, used in simulating microbial growth in biological treatment systems, suggest significant decreases of substrate utilization at lower temperatures. However, it is documented that performance of fixed film treatment systems are not hindered with declining temperatures. Previous studies at the Moorhead, MN, Wastewater Treatment Facility (WWTF) showed significant impacts of temperature on biofilm growth in its moving bed biofilm reactor (MBBR), and studies noted that at low temperatures more biomass was present. Previously, a series of kinetic bench-scale batch tests was performed to measure ammonium removal in the full-scale system. As part of this research, a diffusion based kinetic model was developed to simulate the bench-scale trials and determine if Monod kinetics and temperature corrections properly model fixed film systems. It was found that Monod kinetics and temperature corrections do apply to fixed film system as long as proper consideration is given to the change in biofilm characteristics.

As in any animal production industry, disease is inevitable; therefore, it is imperative that aquaculturists are able to effectively manage the disease and maintain their high production levels in an effort to bridge the gap between supply and demand in the seafood industry that has been caused in part by global over-fishing. This management responsibility lies not only in understanding the impact of the treatment on the cultured species, but also in understanding the impact of the treatment to the aquaculture system as an ecosystem. Currently, there is a narrow variety of chemicals approved by either the Food and Drug Administration (FDA) or the Environmental Protection Agency (EPA) for the treatment of disease outbreaks and water quality issues in aquaculture. Approved chemotherapeutants include oxytetracycline, Romet-30®, copper, and formalin. Additionally, a number of chemicals, such as Chloramine-T and potassium permanganate, are used off-label for the treatment of aquaculture systems. In this research, these six more commonly used chemotherapeutants were analyzed for their impacts to the nitrifying bacteria in aquaculture systems. It was found that three of the chemotherapeutants: oxytetracycline, Romet-30®, and chelated copper caused inhibition to the nitrifying bacteria at the whole cell level as demonstrated in the results from water quality and specific oxygen uptake rate analyses. The nitrification process resumed once the chemotherapeutant was removed from the system, either by a mandatory water change or by natural degradation. The other three chemicals: formalin, Chloramine-T, and potassium permanganate did not result in any significant inhibition to the nitrification process. Experiments on laboratory-cultured nitrifying bacteria confirmed these findings. These experiments also resulted in the observation that the expression of amoA was upregulated by the copper exposure and inhibited by oxytetracycline and Romet-30®, but began to resume as the antibiotics degraded. Comprehensively, the findings of these analyses demonstrated that, although nitrifiers are well-known to be sensitive to their environment, the ability of nitrifying bacteria to continue their oxidative processes following exposure to chemical stress is inherent to the bacteria themselves rather than simply occurring under the protection of a biofilm community as has been suggested. / Ph. D.

There is a significant need to remove ammonia from municipal wastewater to meet increasingly stringent regulations set by Canada, US, and Europe. Although existing conventional biological wastewater treatment technologies are shown to achieve effective ammonia treatment, they are substantially limited by increased operational intensity and cost. Due to these limitations, other cost-effective biological treatment technologies, such as partial nitritation/anammox (PN/A), have become a more attractive solution for nitrogen removal at wastewater resource recovery facilities (WRRF). A moving bed biofilm reactor system (MBBR) operating under a novel design strategy using elevated total ammonia nitrogen (TAN) loading rate has shown promise to achieve robust partial nitritation and the oxidation of TAN with limited oxidation of nitrite without the need for intense operational measures. However, the novel and promising design strategy using elevated TAN loading rate was applied at higher influent TAN concentrations that are typically greater than concentrations in mainstream municipal wastewater. Therefore, the objective of this dissertation is to investigate and optimize the design and performance of a promising elevated loaded partial nitritation MBBR technology for mainstream, municipal wastewater treatment followed by downstream anammox to complete the design of a robust, stable, energy-efficient, and low operational cost total nitrogen removal PN/A system for mainstream wastewaters. The first specific objective of the dissertation is to isolate the optimal design parameter of a mainstream elevated loaded partial nitritation MBBR system. The results identifies optimal distinct elevated surface area loading rate (SALR), hydraulic retention time (HRT), and airflow rate that achieve stable partial nitritation performance (i.e., optimum total ammonia nitrogen (TAN) removal kinetics and percent NOₓ as nitrite) in a mainstream elevated loaded partial nitritation MBBR system. The study shows that TAN SALR, HRT, and airflow rate significantly affect TAN surface area removal rates (SARR) and percent NOₓ as nitrite and, as such, identifies the optimal design parameters (TAN SALR, HRT and airflow rate) of a mainstream elevated loaded partial nitritation MBBR system. A TAN SALR of 5 g TAN/m²∙d, HRT of 2h and airflow rate of 1.5 L/min are identified to provide stable partial nitritation performance with a TAN SARR of 2.3 ± 0.3 g TAN/m²∙d and a percent of NOx as nitrite of 84.8 ± 1.2% in the mainstream elevated loaded partial nitritation MBBR system. The second specific objective further identifies a new design configuration and the mechanism of nitrite oxidation suppression of the mainstream elevated loaded partial nitritation MBBR technology. The results identifies a unique design strategy using an elevated TAN SALR of 5 g TAN/m²∙d to achieve cost-effective, stable, and elevated rates of partial nitritation in an MBBR system under mainstream conditions. The elevated loaded partial nitritation MBBR system achieves a TAN SARR of 2.01 ± 0.1 g TAN/m²∙d and NO₂⁻-N:NH₄⁺-N stoichiometric ratio of 1.15:1, which is appropriate for downstream anammox treatment. The elevated TAN SALR design strategy promotes nitrite-oxidizing bacteria (NOB) activity suppression rather than a reduction in NOB population as the reason for the suppression of nitrite oxidation in the mainstream elevated loaded partial nitritation MBBR system. NOB activity is limited at an elevated TAN SALR, likely due to thick biofilm embedding the NOB population and competition for dissolved oxygen (DO) with ammonia-oxidizing bacteria for TAN oxidation to nitrite within the biofilm structure, which ultimately limits the uptake of DO by NOB in the system. The third specific objective of this research characterizes the effects of distinct mixing and aeration strategies on the performance of the mainstream elevated loaded partial nitritation MBBR technology. This is addressed through a study investigating and comparing the kinetics, biofilm characteristics, and embedded biomass of three distinct mixing and aeration strategies employed to operate the mainstream elevated loaded partial nitritation MBBR system. The study compares the conventional mixing and aeration condition, continuous aeration with mechanical paddle & aeration, and recirculation pump & aeration utilized to optimize the partial nitritation MBBR system to achieve low DO effluent concentrations for optimal downstream anammox treatment. The results show that maintaining mixing and aeration in the elevated loaded partial nitritation MBBR system with recirculation pump & reduced aeration achieves lower effluent DO concentration and stable partial nitritation with appropriate NO₂⁻-N:NH₄⁺-N stoichiometry ratio of 1.09:1 for subsequent anammox treatment compared to operation with continuous aeration or mechanical paddle & aeration. The fourth specific objective of this research investigates the promising elevated loaded PN/A configured system for nitrogen removal under mainstream conditions. This is achieved through the operation of the elevated loaded partial nitritation MBBR system following the anammox unit as a combined two-stage system for nitrogen removal at mainstream municipal concentration. The elevated loaded partial nitritation MBBR system provides optimal NH₄⁺-N:NO₂⁻-N stoichiometric effluent ratio of 1:1.17, resulting in the successful operation of a downstream anammox unit with a total nitrogen removal rate at 0.22 ± 0.2 g N/m²/d and total nitrogen removal efficiency at 74.1 ± 0.7%. The average NO₂⁻-N to NH₄⁺-N molar removal ratio is 1.05 ± 0.1 from the anammox unit. Also, the anammox bacteria (AnAOB) gene copies are at 3.28 ± 0.7 × 10⁸, a value significantly higher than the AOB and NOB gene copies at 9.17 ± 1.1 × 10⁴ and 6.23 ± 1.0, respectively. This confirms that anammox activity is established and nitrogen removal is primarily through the anammox process. The results and overall system performance demonstrate that the combined two-stage mainstream elevated loaded partial nitritation/anammox MBBR system has shown promise and offers great insights for further advancement of the anammox process at mainstream municipal wastewaters. Finally, the economic evaluation and cost comparative analyses conducted show that compared to the conventional biological nitrification/denitrification process for nitrogen removal, the two-stage elevated loaded PN/A system offers a 57.6% savings on energy cost, 100% savings on chemical cost, and 68.7% savings on the cost of sludge disposal. Therefore, the two-stage elevated loaded PN/A system, in addition to high nitrogen removal efficiency, reduced footprint, and ease of operation, is also economically favorable and reduces the overall operational cost of wastewater treatment system by 61.6%, thus saving up to an average of 3.7 million CAD every year.

Urea is the predominant ammonium-forming nitrogen (N) source applied in delayed-flood rice because of its high N content (46%) and relatively low cost. Nitrogen applied prior to flooding can be lost by multiple mechanisms such as ammonia volatilization or nitrification/denitrification. In recent years, technological advancements have provided alternative enhanced efficiency fertilizer additives with potential to be incorporated in rice production to reduce N losses. Research was conducted at the Mississippi State University Delta Research and Extension Center from 2018 to 2020 to determine the effects of broadcast applications of nitrapyrin at two specific growth stages to enhance fertilizer-N recovery efficiency, determine optimal application methods of nitrapyrin with urea, determine the effects of nitrapyrin mixed with different herbicides for weed control, and to evaluate nitrapyrin efficacy alone and in conjunction with N-(n-butyl) thiophosphoric triamide (NBPT) to reduce ammonia volatilization. In the current research, there was no effect on grain yield responses from the addition of nitrapyrin regardless of soil textures or application timing. Broadcast applications of nitrapyrin did not improve fertilizer-N recovery efficiency regardless of soil texture or application timing. Differences in rice grain yield were not observed with respect to nitrapyrin application method or NBPT combination for clay and silt loam textures. Barnyardgrass control was unaffected with nitrapyrin applied with different herbicides. Lastly, nitrapyrin was ineffective at reducing ammonia volatilization and resulted in a similar trend to urea alone. Efficacy from nitrapyrin plus NBPT was not different from NBPT alone at reducing N losses. Nitrapyrin efficacy can be influenced by soil texture, application timing, or application method. Implementing nitrapyrin as an enhanced efficiency fertilizer additive to mitigate N losses is inconsistent, and rice grain yields will vary based on environmental and soil conditions.

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