Dissolved organic nitrogen (DON) represents a major pool of fixed, reactive nitrogen in marine systems. It is now recognized that this pool can support primary production and the ability of some algal species to exploit DON compounds as sources of Nitrogen (N) may indicate that specific DON components can exert selective pressure on the composition of the phytoplankton community. In this study the ability of monocultures of ecologically-relevant algal species from the English Channel (Emiliania huxleyi, Micromonas pusilla, Alexandrium minutum and Chaetoceros peruvianus) to grow with DON as the only N source was examined using different artificial media. Among the two tested artificial seawater recipes, Aquil* was preferred as it contained lower micronutrient concentrations, and gave better growth results for all used species. In order to constrain the DON uptake to algae alone, a method for bacterial removal was tested using antibiotic additions. Both Slocombe antibiotic mixture (Cefotaxime-Carbenicillin-Kanamycin-AugmentinTM) and Penicillin-Streptomycin-Neomycin used were effective and not toxic to the algae. Incubation with the antibiotic up to 48 hours and a transfer period into antibiotic-free medium after 72 hours proved to be effective. However, the treatment removed bacteria in A. minutum cultures only; further treatment would be required for the other species to be cultured axenically. The ability to use DON was tested for the above mentioned species using the amino acid L-Arginine (ARG) as the sole N source, and growth was compared with nitrate-containing cultures of the same species. All the selected species grew in both NOᴈ‾ and in ARG, reaching lower final densities when incubated with ARG, although these were not significant. This study has shown that E. huxleyi, A. minutum, M. pusilla and C. peruvianus can grow on organic N, either by direct or indirect uptake, and develop comparable biomasses to species using inorganic N. Both C. peruvianus and M. pusilla cultures contained dissolved ammonium at the end of the experimental period, indicating potential indirect use by the algae of organic N converted to inorganic N by bacteria. A. minutum grew in the presence of ARG along with the cosmopolitan E. huxleyi; N-demand estimates, based on the molar concentration of N-ARG consumed, correlated with the final cell density, indicating that the species did not develop on inorganic N produced from ARG mineralisation, but directly on the ON substrate. Since A. minimum has been linked to harmful algal blooms, and E. huxleyi contributes significantly to oceanic CaCOᴈ deposition, their ability to utilise DON has environmental consequences in addition to the oceanic N-budget. Climate change scenarios predict both episodic conditions of elevated rainfall and extended periods of dry conditions leading to variable riverine inputs to coastal areas, altered nitrogen to phosphorus (N:P) ratios, and changes in the inorganic to organic balance of the nutrient pools. Organic N can constitute up to 69 % of the total N pools, respectively, making it crucial, to understand the cycling of this fraction in coastal waters, and how changes in the composition of nutrient pools could impact on marine ecosystem function and health.

Dissolved organic nitrogen (DON) represents a significant portion (25-80%) of total dissolved nitrogen in the final effluent of wastewater treatment plants (WWTPs). DON in treated wastewater, once degraded, causes oxygen depletion and/or eutrophication in receiving waters and should be reduced prior to discharge. Biodegradability, bioavailability, and photodegradability are important characteristics of wastewater derived DON and are subjects of research in this dissertation. Four research tasks were performed. In the first task, laboratory-scale chemostat experiments were conducted to examine whether solids retention time (SRT) could be used to control DON and biodegradable DON (BDON) in treated wastewater. Nine different SRTs from 0.3 to 13 were studied. There was no correlation between effluent DON and SRTs. However, BDONs at SRTs of 0.3 to 4 days were comparable and had a decreasing trend with SRTs after that. These results indicate the benefit of high SRTs in term of producing effluent with less BDON. The second task was a comprehensive year-round data collection to study the fate of DON and BDON through the treatment train of a trickling filter (TF) WWTP. The plant removed substantial amounts of DON (62%) and BDON (76%) mainly through the biological process. However, the discharged concentrations in the effluent were still high enough to be critical for a stringent total nitrogen discharge limit (below 5 mg-N/L). Evolution of bioavailable DON (ABDON) along the treatment trains of activated sludge (AS) and TF WWTPs and relationship between ABDON and BDON were examined in the third task. ABDON exerted from a combination of bacteria and algae inocula was higher than algae inoculated ABDON and bacteria inoculated BDON suggesting the use of algae as a treatment organism along with bacteria to minimize effluent DON. The TF and AS WWTPs removed 88% and 64% of ABDON, respectively. In the last task, photodegradable DON (PDON) in primary wastewater and final effluent from TF and AS WWTPs was studied. PDON and BDON fractions of DON data in the final effluent of TF and AS WWTP samples elucidate that photodegradation is as critically important as biodegradation when mineralization of effluent DON is a concern in receiving waters.

The features of upwelled water are cold, salty and nutrient-rich. However, factors such as the air-sea exchanges of heat affect temperature, and freshwater input from rivers, precipitation and evaporation affect salinity. As biologically important elements are mostly in the dissolved inorganic forms in young upwelled waters, and are mostly in the particulate organic forms in old upwelled waters, the aging status of upwelled waters can be expressed as the relative percentages of biologically important elements in the inorganic and organic forms. Further, nutrients may be consumed by biological productivity. For these reasons, we hereby judge upwelling in the Taiwan Strait (TS) between 2000 and 2002 by the Degree of Nutrient Consumption (DNC, DNCC = and DNCX = ¡AX is nitrogen or phosphorus). The value of DNC is low in young upwelled waters but high in old upwelled waters. In summer, autumn and winter, waters at, or east of, a front in the northeastern Taiwan Strait were affected by the Kuroshio off eastern Taiwan. This front divides the Kuroshio water, the South China Sea (SCS) water that flows through the TS and the Coastal China Current water (in winter). The implications are that not all currents in the Taiwan Strait flow in a northerly direction, even in summer. Because the axis of Kuroshio moved away from eastern Taiwan and upwelling weakened in SCS in 2002, salinity east of the front was fresher, and nutrient and DON were lower in 2002 than 2001. On the other hand, upwelling induced higher DON west of the front. In August, 2002, the water in the southern TS was higher in temperature, more salty, but nutrient and DON were lower than in 2001 because of weakened upwelling in the SCS, and water that intruded into the TS had a higher percentage of Kuorshio. The trend of upwelling, DNCC,P,N was along the west Penghu Channel from bottom to surface. Rates of temperature, salinity and DNCC,P,N variation were greater during 2001 than in 2002, reflecting slower rate of upwelling in 2002.

abstract: Population growth and fresh water depletion challenge drinking water utilities. Surface water quality is impacted significantly by climate variability, human activities, and extreme events like natural disasters. Dissolved organic carbon (DOC) is an important water quality index and the precursor of disinfection by-products (DBPs) that varies with both hydrologic and anthropogenic factors. Granular activated carbon (GAC) is a best available technology for utilities to meet Stage 2 D/DBP rule compliance and to remove contaminants of emerging concern (CECs) (e.g., pharmaceutical, personal care products (PCPs), etc.). Utilities can operate GAC with more efficient and flexible strategies with the understanding of organic occurrence in source water and a model capable predicting DOC occurrence. In this dissertation, it was found that DOC loading significantly correlated with spring runoff and was intensified by dry-duration antecedent to first flush. Dynamic modeling based on reservoir management (e.g., pump-back operation) was established to simulate the DOC transport in the reservoir system. Additionally, summer water recreational activities were found to raise the level of PCPs, especially skin-applied products, in raw waters. GAC was examined in this dissertation for both carbonaceous and emerging nitrogenous DBP (N-DBP) precursors (i.e., dissolved organic nitrogen (DON)) removal. Based on the experimental findings, GAC preferentially removes UV254-absorbing material, and DOC is preferentially removed over DON which may be composed primarily of hydrophilic organic and results in the low affinity for adsorption by GAC. The presence of organic nitrogen can elevate the toxicity of DBPs by forming N-DBPs, and this could be a major drawback for facilities considering installation of a GAC adsorber owing to the poor removal efficiency of DON by GAC. A modeling approach was established for predicting DOC and DON breakthrough during GAC operation. However, installation of GAC adsorber is a burden for utilities with respect to operational and maintenance cost. It is common for utilities to regenerate saturated GAC in order to save the cost of purchasing fresh GAC. The traditional thermal regeneration technology for saturated GAC is an energy intensive process requiring high temperature of incineration. Additionally, small water treatment sites usually ship saturated GAC to specialized facilities for regeneration increasing the already significant carbon footprint of thermal regeneration. An innovative GAC regeneration technique was investigated in this dissertation for the feasibility as on-site water treatment process. Virgin GAC was first saturated by organic contaminant then regenerated in-situ by iron oxide nanocatalysts mixed with hydrogen peroxide. At least 70 % of adsorption capacity of GAC can be regenerated repeatedly for experiments using modeling compound (phenol) or natural organic matter (Suwannee River humic acid). The regeneration efficiency increases with increasing adsorbate concentration. Used-iron nanocatalysts can be recovered repeatedly without significant loss of catalytic ability. This in-situ regeneration technique provides cost and energy efficient solution for water utilities considering GAC installation. Overall, patterns were found for DOC and CEC variations in drinking water sources. Increasing concentrations of bulk (DOC and DON) and/or trace organics challenge GAC operation in utilities that have limited numbers of bed-volume treated before regeneration is required. In-situ regeneration using iron nanocatalysts and hydrogen peroxide provides utilities an alternative energy-efficient operation mode when considering installation of GAC adsorber. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2012

The Deepwater Horizon (DWH) oil spill in the Gulf of Mexico (GoM) in the spring of 2010 introduced 4.4 million of barrels of oil to the ecosystem. Some biodegradation of the oil occurs when microorganisms, particularly bacteria, metabolize the oil as a carbon source. During this process, the microbes also require nutrients for energy. An introduction of oil at this magnitude has the ability to induce large blooms of microbes, which in turn can affect nutrient concentrations. Microbial petroleum degradation decreases nutrient concentrations, whereas the microbial assimilation and decay of organic matter increase nutrient concentrations. This study assessed whether any changes in nitrate, ammonium, and/or phosphate concentrations from historical levels could be attributed to the oil spill as a result of biodegradation, and how those changes can impact the GoM ecosystem. Nutrient samples were collected at discrete depths throughout the water column, in a cross-shelf transect inland from the spill site outside the DeSoto Canyon, in August 2010, February 2011, and May 2011 (four months to one year after the spill). In August 2010, a subsurface oil plume was found at depths of 1000 m to 1200 m. At the same depth of ~1000 m, a significant decrease in nitrate was observed, indicating the biodegradation of oil by heterotrophic bacteria of the aphotic zone, compared to earlier data during August 2000, when no known oils were present. Overall temporal increases in ammonium and dissolved organic nitrogen (DON) were observed both in near-surface waters and at an intermediate depth of ~400 m next to the walls of the DeSoto Canyon, suggesting an incremental die-off of both plankton and benthic organisms during accelerated recycling of nutrients. Continued decreases of phosphate were observed into February 2011, supporting ongoing biodegradation then as well. By May 2011, however, there were more increases in near-surface ammonium concentrations, compared to April 2000, with the implication that continued interseasonal recycled nitrogen accumulations may have been due to a decadal ecological regime shift, after a combination of top-down overfishing, petroleum perturbations, and/or increases of toxic harmful algal blooms (HABs).

Nitrogen (N) is known to be a limiting factor in peatlands and as such, the vegetation present has adapted to living in low N conditions. This makes such ecosystems particularly vulnerable to increases in the deposition of reactive N (Nr), which may result in significant changes to its biodiversity and biogeochemistry. Since the industrial revolution, the amount of anthropogenic Nr globally has increased from ~15 Tg N y-1 in the 1860’s to ~187 Tg N y-1 in 2005, and is estimated to reach ~267 Tg N yr-1 by 2050 (Galloway et al. 2004, Galloway et al. 2008). Consequences include acidification, loss of biodiversity, changes in vegetation, N-saturation, eutrophication, health impacts and the release of greenhouse gases.Objectives of this thesis were (i) to measure key components of the N-budget at Auchencorth Moss, a Scottish moorland, for a two year period (Jan 2009 – Dec 2010) and (ii) to compare current deposition rates with those measured 14/15 years previously. Annual fluxes of N inputs were estimated from measurements of wet only deposition, estimates of N-fixation deposition and from atmospheric deposition modelled from hourly concentrations of N containing gases and aerosols. Exports were estimated from stream measurements and from atmospheric emissions modelled from hourly concentrations. Organic N is often an underreported part of the N-cycle, but the results presented here suggest it is an important part of the N story. An attempt to identify (dissolved organic nitrogen) DON compounds in both precipitation and stream water was made using GC×GC-NCD. Ten unique compounds were detected, of which only five could be identified: pyrrole, benzonitrile, dodecylamine, N-nitrosodipropylamine and decylamine. Pyrrole, benzonitrile and three unknown compounds were present in both precipitation and stream samples. Ammonia (NH3) fluxes were measured over a 7 month period in 2009 using a wet-chemistry gradient system with online analysis and calculated with the aerodynamic gradient method. The results were used to refine a bi-directional dynamic exchange model. Several parameters were updated, including an increased stomatal emission potential from 180 to 350, a reduction of the minimum cuticular resistance (Rw,min) used to calculate Rw from 20 s m-1 to 15 s m-1 and an increase in the leaching rate (Kr¬) from the leaf surfaces from -0.01 to -0.1 s-1. The exchange parameterisations used to estimate HNO3, HONO and the aerosol compounds were taken from the literature and earlier studies at the site.Overall, Auchencorth was found to accumulate N, with deposition exceeding export by -1.61 kg N ha-1 yr-1. The main N deposition was from NH3, followed by wet deposition of ammonium. DON, which is not routinely included in N budgets, contributed 6.5% of total deposition. The largest loss of N was as DON via the stream with N losses of -5.31 kg N ha-1 yr-1 or 71.8% of total export. Between 1995 and 2009/2010, deposition decreased by 0.81 kg N ha-1 yr-1, with the wet deposition of inorganic nitrogen decreasing by 25.2%, but dry deposition increasing by 12.5%. DON, N2O and N-fixation were not included in the comparison as they were not measured in 1995.This thesis has demonstrated that DON is an important parameter in the overall N budget, and should be routinely measured when assessing the N status of ecosystems.

Antihistamines are a group of pharmaceuticals that enter the environment and may affect microorganisms that regulate decomposing of organic matter and the release of carbon and nitrogen from soils. In this study I investigated if the antihistamine fexofenadine decreases the concentration of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) from humus. I used humus from two vegetation types (heath and meadow), and used a batch experiment approach, where humus was mixed with fexofenadine solutions (2000 ng/L and 20 000 ng/L). After ten days in room temperature, the samples with fexofenadine were compared with batches containing pure water solutions (control). I found differences in the concentration of DOC, DON and pH that were dependent on the studied vegetation types. There were higher concentrations of DOC and DON in heath (35.9 mg/L and 2.0 mg/L) than in the more nutrient rich meadow (9.2 mg/L and 0.5 mg/L). The latter vegetation type did also have a higher pH. In contrast to my hypothesis, the concentration of DOC and DON was not significantly affected by the fexofenadine. However, if considering a 90%-level of significance, there were a significant interaction effect where concentration of DOC decreased in meadow and increased it in heath. A possible vegetation specific effect of fexofenadin seems plausible as microbial biomass and activity in the vegetation types are known to differ. My findings cannot exclude that fexofenadine stimulates degradation of DOC in the more microbial active meadow humus, but not in the humus of heath where activities are lower.

Antihistamines are a group of pharmaceuticals that enter the environment and may affect microorganisms that regulate decomposing of organic matter and the release of carbon and nitrogen from soils. In this study I investigated if the antihistamine fexofenadine decreases the concentration of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) from humus. I used humus from two vegetation types (heath and meadow), and used a batch experiment approach, where humus was mixed with fexofenadine solutions (2000 ng/L and 20 000 ng/L). After ten days in room temperature, the samples with fexofenadine were compared with batches containing pure water solutions (control). I found differences in the concentration of DOC, DON and pH that were dependent on the studied vegetation types. There were higher concentrations of DOC and DON in heath (35.9 mg/L and 2.0 mg/L) than in the more nutrient rich meadow (9.2 mg/L and 0.5 mg/L). The latter vegetation type did also have a higher pH. In contrast to my hypothesis, the concentration of DOC and DON was not significantly affected by the fexofenadine. However, if considering a 90%-level of significance, there were a significant interaction effect where concentration of DOC decreased in meadow and increased it in heath. A possible vegetation specific effect of fexofenadin seems plausible as microbial biomass and activity in the vegetation types are known to differ. My findings cannot exclude that fexofenadine stimulates degradation of DOC in the more microbial active meadow humus, but not in the humus of heath where activities are lower.

This study is aimed to provide comprehensive evaluation and mechanistic understanding of the impact of process intensification techniques applied in main and side stream wastewater treatment on biosolids management in terms of anaerobic digestion enhancement, dewaterability improvement, odor mitigation, as well as phosphorus and nitrogen removal. The first part of this study was conducted to understand the effect of anaerobic digester solids retention time (SRT) on odor emission from biosolids. A kinetic model and inhibitory studies showed the emission of methanethiol (MT), a representative odor compound, was primarily determined by the dynamic concurrence of MT production from amino acid and utilization by methanogens in the course of anaerobic digestion. MT emission pattern follows a bell-shape curve with SRT in anaerobic digesters. However, for digested and dewatered biosolids, SRT ranging from 15 to 50 days in anaerobic digesters demonstrated insignificant effect on the odor emission from biosolids. In contrast, the peak odor emission was found to exponentially increase with both shear intensity and polymer dose applied during dewatering. The second part of this study investigated the impact of process intensification practices on sludge dewatering performance. The integration of high-rate activated sludge process and anaerobic digestion elevated the sludge orthophosphate level, leading to struvite scaling and dewaterability deterioration. Superior orthophosphate removal, significant improvement of sludge dewaterability, and favorable economics were achieved through sludge conditioning by cerium chloride. Continuous flow aerobic granulation technology offered significant process intensification of mainstream treatment trains. However, its impact on biosolids management was not studied. This study showed that there was little dewaterability difference between aerobic granular sludge and activated sludge when polymer was not added. However, about 75% polymer saving and improved dewatering performance were observed with polymer addition. When subjected to high shear, a greater dewaterability deterioration was observed for granular sludge than activated sludge. The last part of this study is focused on the impact of anaerobic digestion process intensification through thermal treatment including pre-pasteurization, thermophilic anaerobic digestion, temperature phased anaerobic digestion, and thermal hydrolysis pretreatment. Improved methane production, pathogen reduction, dewatering performance, and odor mitigation were observed with the involvement of these high-temperature processes. However, special cautions and measure should be taken during the start-up of these high rate processes as they are more liable to digester souring. In addition, the in-depth understanding of the mechanism of recalcitrant dissolved organic nitrogen formation during sludge thermal pretreatment was provided. / Doctor of Philosophy / This study is aimed to provide comprehensive evaluation and mechanistic understanding of the impact of process intensification techniques applied in main and side stream wastewater treatment on biosolids management in terms of anaerobic digestion enhancement, dewaterability improvement, odor mitigation, as well as phosphorus and nitrogen removal. The first part of this study was conducted to understand the effect of anaerobic digester solids retention time (SRT) on odor emission from biosolids. A kinetic model and inhibitory studies showed the emission of methanethiol (MT), a representative odor compound, was primarily determined by the dynamic concurrence of MT production from amino acid and utilization by methanogens in the course of anaerobic digestion. MT emission pattern follows a bell-shape curve with SRT in anaerobic digesters. However, for digested and dewatered biosolids, SRT ranging from 15 to 50 days in anaerobic digesters demonstrated insignificant effect on the odor emission from biosolids. In contrast, the peak odor emission was found to exponentially increase with both shear intensity and polymer dose applied during dewatering. The second part of this study investigated the impact of process intensification practices on sludge dewatering performance. The integration of high-rate activated sludge process and anaerobic digestion elevated the sludge orthophosphate level, leading to struvite scaling and dewaterability deterioration. Superior orthophosphate removal, significant improvement of sludge dewaterability, and favorable economics were achieved through sludge conditioning by cerium chloride. Continuous flow aerobic granulation technology offered significant process intensification of mainstream treatment trains. However, its impact on biosolids management was not studied. This study showed that there was little dewaterability difference between aerobic granular sludge and activated sludge when polymer was not added. However, about 75% polymer saving and improved dewatering performance were observed with polymer addition. When subjected to high shear, a greater dewaterability deterioration was observed for granular sludge than activated sludge. The last part of this study is focused on the impact of anaerobic digestion process intensification through thermal treatment including pre-pasteurization, thermophilic anaerobic digestion, temperature phased anaerobic digestion, and thermal hydrolysis pretreatment. Improved methane production, pathogen reduction, dewatering performance, and odor mitigation were observed with the involvement of these high-temperature processes. However, special cautions and measure should be taken during the start-up of these high rate processes as they are more liable to digester souring. In addition, the in-depth understanding of the mechanism of recalcitrant dissolved organic nitrogen formation during sludge thermal pretreatment was provided.

Abstract The South China Sea (SCS) is the largest marginal sea in the world and connects with the East China Sea (ECS) through the Taiwan Strait (TS). This study investigates the distribution and biogeochemical behavior of both particulate and dissolved organic matter in the SCS and the TS based on samples collected on several cruises of the R/V Ocean Researchers I and III. Dissolved inorganic nitrogen and phosphorus (DIN and DIP), particulate organic carbon and nitrogen (POC and PON) as well as dissolved organic nitrogen and phosphorus (DON and DOP) concentrations were determined. Concentrations of DON and DOP in the SCS are in the range of 1.2-9.9 mMN and 0.04-0.21 mMP, respectively. The surface DON concentration is the highest in the northern SCS, whereas it is the lowest in the southern part. The DOP does not show a similar trend. DON and DOP concentrations all decrease with depth but increase slightly near the bottom, perhaps on account of sediment resuspension. Because of the preferential degradation of DOP over DON, the maximum concentration of DOP appears at a shallower depth than that of DON. Approximately 11 % and 2 % of DIN and DIP respectively are attributed to the degradation of DON and DOP above 500 m in the SCS. Concentrations of POC and PON in the SCS are in the range of 1.06-2.84 mMC and 0.07-0.36 mMN, respectively. The distributions of POC and PON show similar patterns with a correlation coefficient of 0.97. The concentrations of these are the highest at the surface layer, decrease with depth, but then increase slightly near the bottom, perhaps again because of resuspension of the bottom sediments. The ratio of PON/POC is 0.138 in the euphotic zone, a value close to the Redfield ratio of 0.15. In the TS and the adjacent coastal zones, the effect of terrestrial input is obvious and results in higher POC, PON, DON and DOP nearshore. Ranges of these concentrations are 0.06-59.6 mMN, 0.01-1.29 mMP, 3.80-57.1 mMC and 0.19-3.4 mMN, respectively. There was an attempt to use the one-dimensional diffusion-advection model to estimate the DIN and DIP production rates and the DON and DOP consumption rates over the depth range of 900-2500 m. These values are, respectively, 0.036, 0.006, 0.021 and 0.002 mmol/kg/yr.