Inaug.-diss.--Göttingen. / Lebenslauf.

Thesis (Ph.D.)--University of Delaware, 2005. / Principal faculty advisor: Daniel K. Cha, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

No description available.

The purpose of using chemical nitrification inhibitors is to delay the oxidation of ammoniacal fertilizers during the early part of the growing season in order to minimize N losses prior to the period of maximum crop uptake. Since NH₄⁺ is electrostatically attracted to soil particles, leaching losses would be minimized, and denitrification losses could not occur in the absence of NO₃⁻. Thus, smaller amounts of fertilizer N would be required, resulting in lower inputs of money and energy as well as less potential for environmental pollution. A study (Chapter Two) was initiated in the fall of 1977 to determine if ATC could minimize overwinter losses of fall-applied N. Urea (200 kg N/ha) with or without a 1% coating: of ATC (4-amino-l,2,4-triazole) was banded or broadcast onto a silt soil on November 8, when the soil temperature at 10 cm depth was 1.9°C. The soil was sampled to a depth of 90 cm at approximately one month intervals until April, and NH₄⁺ and NO₃⁻ were determined. In the banded plots, some nitrification occurred prior to January, but from this date unti1 March there was very little change in soil NH₄⁺ levels. Overall, from December to April, there were 70 and 48% decreases in the 0-15 cm plots without and with ATC, respectively. In all the broadcast plots, regardless of ATC treatment, nitrification proceeded steadily throughout the sampling period, with 93 and 85% decreases from the December 0-15 cm NH₄⁺ levels in the non-ATC and ATC plots, respectively. It is concluded that ATC is partially effective in minimizing N losses when applied in the fall as a band with urea, but when broadcast there is no effect on nitrification. Leaching of the water-soluble ATC was the likely cause of its poor effectiveness. Significant leaching of urea from the zone of application was also found to occur during the first month following its application. A laboratory study (Chapter Three) was conducted to determine the influence of the nitrification inhibitors ATC and N-Serve [2-chloro-6-(trichloromethyl)-pyridine] on urea hydrolysis in a silt soil at 2 and 12°C. There was no delay of ureolysis caused by the presence of these chemicals, even at 20 times the recommended application rate. At 2°C the rate of hydrolysis was about half that at 12°C, with 21 and 7 days being required for complete hydrolysis at 2 and 12°C, respectively. These results suggest that leaching of urea may occur following its application to a cold soil during periods of heavy precipitation as was found in the winter nitrification study (Chapter Two). A series of field experiments (Chapter Four) was conducted with silage corn (Zea mays L.) to compare the effectiveness of the nitrification inhibitors ATC and N-Serve in a loamy sand and a silt. Urea was coated with the inhibitors at a rate of 1% of active ingredient per weight of N and applied as a band or broadcast in the spring of 1977 and 1978. Neither inhibitor significantly affected nitrification when applied as a broadcast treatment to either soil. In the silt, both inhibitors were equally effective in delaying nitrification when banded, whereas in the loamy sand ATC was much more effective than N-Serve. The effectiveness of N-Serve persisted much longer in the silt (86 days) than in the loamy sand (23 days). This suggested that volatilization of N-Serve severely limited its effectiveness in the loamy sand. There was no significant improvement in crop yields or N content due to inhibitor treatment in either soil. / Land and Food Systems, Faculty of / Graduate

The new Canadian federal wastewater regulations, which restricts the release of ammonia from treated wastewaters, has resulted in upgrade initiatives at many water resource recovery facilities across the country to reduce the discharge of ammonia into our natural waters. The objective of this dissertation is therefore to investigate and optimize the performance of two attached growth technologies for rural and peri-urban/urban municipal ammonia removal. In particular, the first specific objective of this dissertation is to investigate the performance and microbial response of the BioCord technology as an upgrade system for the post-carbon removal nitrification of rural wastewaters. The second specific objective is to study the start-up of an attached growth anammox technology to enhance current knowledge pertaining to anammox biofilm attachment, growth and maturation. The results pertaining to the first specific objective of this research, a study of the design and optimization of the BioCord technology, demonstrates a recommended design rate for the post-carbon removal, nitrifying BioCord system of a surface area loading rate (SALR) of 1.6 NH4⁺-N/m²·d and up to 1.8 NH4⁺-N/m²·d with steady ammonia-nitrogen removal efficiencies greater than 90% and steady and low solids production rate up to 0.26 g TSS/d. A loss of system stability and biofilm sloughing, identified as fluctuating ammonia removal rates and solids production rates, were observed at elevated SALRs of 2.1 and 2.4 g -N/m²·d. The microbial results indicate that the meso-scale structure of the biofilm and the micro-animal population are directly affected by operational conditions. Enhanced air scouring configuration is shown to be a potential optimization strategy to prevent the clogging of biofilm pores and improve the system stability in terms of solids production rate in the BioCord technology. The results pertaining to the second specific objective of this research, the study of inoculation and carrier modification strategies for the rapid start-up of attached growth anammox technology, demonstrates significantly higher kinetics, faster biofilm growth and greater anammox bacteria enrichment on the silica-functionalized carriers and pre-seeded denitrifying carriers in a system inoculated with detached anammox biofilm mass during the early stages of attachment and growth of start-up. The study suggests that the use of the silica-functionalized and pre-seeded denitrifying carriers along with detached anammox biofilm inoculation has the potential to accelerate the anammox biofilm attachment, growth and maturation.

The wastewater treated at the Hopewell Regional Wastewater Treatment Facility (HRWTF) is very unique both because it is comprised of effluents of seven different industries in the area in addition to the domestic wastewater in the area, and because it reaches high temperatures in the basins, often above 45oC during the summer. Four different bench scale systems consisting of continuously stirred tank reactors (CSTRs) in series were operated during the summer of 1997 to quickly assess the feasibility of nitrifying and denitrifying the total flow at HRWTF down to a final effluent total nitrogen concentration of 10 mg-N/L or less. The four main treatment strategies tested were: aerobic/anoxic treatment of the final effluent of HRWTF at moderate temperatures (approximately 30oC); anaerobic/anoxic/aerobic (A2/O) treatment of the primary effluent of HRWTF at moderate temperatures; treatment of the effluent of one of the industries which had a high ammonia wastewater and which was originally believed to contain nitrification inhibitors; and fully aerobic treatment of the primary effluent of HRWTF at high temperatures (of approximately 40 to 45oC) with an activated sludge gradually acclimated to such temperatures over the course of two months. At the end of the study, a two-week high temperature study was conducted on the system which had been treating the secondary effluent all summer with the same activated sludge which was acclimated only to temperatures around 30oC. The fully aerobic high temperature system which had been nitrifying the primary effluent all summer was converted to a modified Lutzack-Ettinger (MLE) process at the end of the study to test whether the primary effluent could be denitrified as well as nitrified at high temperatures with the sludge acclimated to high temperatures. All four of the main treatment strategies demonstrated that nitrification and denitrification of either the total flow or the high ammonia side stream could be achieved down to the desired total nitrogen concentrations. The high temperature study conducted on the system which had been treating the secondary effluent all summer indicated that the sudden increase from approximately 30oC to approximately 40oC over a twenty-four hour period, similar to the sudden temperature increase which occurs every spring at HRWTF, quickly ends nitrification in a system not acclimated to high temperatures, while denitrification and COD removal is hardly affected by such a temperature change. While the nitrification performance of the gradually acclimated system treating the primary effluent at high temperatures was adequate, problems maintaining a consistent MLVSS or ETSS concentration suggested that the high temperatures seen in the basins at HRWTF are likely to make consistent treatment difficult. As a result of considering both capital cost requirements and quality of treatment, the bench scale testing suggested that the most likely candidates for successful treatment of the total flow down to desired total nitrogen concentrations would involve either the A2/O treatment of the primary effluent of HRWTF, possibly with the addition of a cooling tower, or A2/O treatment of the high ammonia side stream, possibly involving the dilution of the wastewater with one of the other flows sent to HRWTF. It was concluded that pilot scale evaluation of the two options was required for a final design decision, and pilot scale evaluation was being performed when this thesis was completed. / Master of Science

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Nitrification, the chemoautotrophic process via which ammonium-nitrogen (NH₄-N) is converted to nitrate-nitrogen (NO₃-N), is an important nitrogen (N) transformation in stream ecosystems. Experimental addition of dissolved organic carbon (DOC) has been shown to inhibit rates of nitrification, and rates have been stimulated by NH4-N addition. Insights regarding the role of particulate organic matter (POM) in this scenario could further enhance our understanding of linkages between ecosystem carbon (C) and N cycles. Hugh White Creek, a headwater stream located in the southern Appalachian mountains of North Carolina, USA, receives large amounts of allochthonous POM inputs each fall. To address the effects of these inputs on nitrification, I conducted a seasonal survey of organic matter standing stocks and nitrification rates along with experimental manipulation of dissolved C and N supplies in stream sediment microcosms to determine: 1) how rates of nitrification compare across seasons, and 2) to what extent nitrification rates are influenced by seasonal changes in standing stocks and relative abundances of both sedimentary and dissolved forms of C and N. Rates of nitrification were most closely and positively related to rates of ammonification, which, in turn were negatively related to C:N of fine benthic organic matter (FBOM). Uniform additions of C and N throughout the year had different effects on rates of nitrification and ammonification due to their changing relative importance as sediment organic matter stocks were depleted and underwent changes in quality. Slow rates of nitrification for much of the year could be attributed to large quantities of C relative to N in stream sediments. To the extent that changes in OM stocks dictate change in C and N availability, seasonal patterns in OM dynamics represent changes in ecosystem structure relevant to rates of nitrification, emphasizing the importance of terrestrial/aquatic linkages for predicting rates of N transformation in aquatic ecosystems. / Master of Science