Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 145-151).

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Chlorine dioxide has been used in drinking water treatment for the reduction of trihalomethanes and tastes-and-odors. Recently, chlorine dioxide was implicated as the source of offensive "cat-urine-like" and "kerosene-like" odors in drinking water. The purpose of this project was to determine the cause of odors observed in customers homes at times when chlorine dioxide was being applied to drinking water. Data were obtained through a survey and field sampling at utilities experiencing odor events. Once the cause was determined, potential water-treatment procedures were evaluated in laboratory-scale studies. Results from a survey sent to water utilities throughout the United States showed that customers who recently had installed new carpeting complained of odors more than those who had not. The use of chlorine dioxide caused responses to intensity of certain tastes-and-odors to increase, two of these odors were cat urine and kerosene. Field sampling at two water companies during odor events resulted in the discovery of low-levels of residual chlorine dioxide (0.2-0.7 mg/L) at the tap's of customers. Both the cat-urine- and kerosene-like odors were detected by the research team. To verify a proposed mechanism of odor generation, chlorine dioxide was volatilized in a room with new carpeting. Both odors were produced in amounts great enough to be easily detected by the entire panel. The removal of residual chlorite from drinking water would block a mechanism by which chlorine dioxide may be reformed from reactions between residual chlorite and free chlorine added for distribution system residual maintenance. Chlorite was removed by powdered activated carbon (PAC) enmeshed in alum floc in laboratory-constituted water and Po River water. A high level of PAC (50 mg/L) was required to effect good removal. A simulated floc-blanket clarifier effectively removed high levels of chlorite (>5 mg/L) from drinking water for long periods (12 hours) when PAC in high concentration was enmeshed in the floc. Chlorine dioxide reformed in the distribution system of two water companies. When customers opened water faucets, chlorine dioxide volatilized into the room and reacted with organic compounds present in the household air (e.g. from new carpeting) producing the offensive cat-urine-like and kerosene-like odors. The reformation of chlorine dioxide could be effectively eliminated if residual chlorite could be removed by contact with high levels of PAC enmeshed in an alum floc such as one could produce in a floc-blanket clarifier. / Master of Science

Anaerobic digestion is widely used for stabilization of solids in sewage sludges. Recent changes in the priorities and goals of digestion processes are focusing more attention on the efficiency of these processes. Increasing hauling cost and restrictions for land applications are two factors which are driving the increased attention to digestion efficiency. Noxious odor production from the land applied biosolids is another important issue related to digestion efficiency. Existing anaerobic digestion or aerobic digestion processes failed to provide simultaneous solution to biosolids related problems i.e. simultaneous VS reduction, better dewatering of biosolids and lesser odors from the biosolids. Studies done by Novak et al. (2004) using different activated sludges show that anaerobic-aerobic digestion and aerobic-anaerobic digestion both increase volatile solids reduction compared to a single digestion environment. They proposed that there are 4 VS fractions in sludges: (1) a fraction degradable only under aerobic conditions, (2) a fraction degradable only under anaerobic conditions, (3) a fraction degradable under both anaerobic and aerobic conditions, and (4) a non degradable fraction. It has also been found (Akunna et al., 1993) that anaerobic-aerobic sequential treatment of wastewater can help in achieving substantial nitrogen removal. These results suggest that sequential anaerobic-aerobic digestion can address multiple biosolid related problems. This study was designed to understand the effect of sequential anaerobic-aerobic digestion on the properties of resulting effluent biosolids. The study was carried out in two operation phases and during both phases one digester was maintained at thermophilic conditions and the other at mesophilic temperature conditions. In first operation phase (Phase-I) thermophilic digester was operating at 20 day SRT and mesophilic anaerobic digester was at 10 day SRT. The aerobic digesters following anaerobic digesters were operating at 6 day SRT. In second operation phase (Phase-II), both thermophilic and mesophilic anaerobic digesters were operating at 15 day SRT and both had two aerobic digesters operating in parallel at 3 day and 6 day SRTs. In addition, batch experiments were also conducted to measure the performance of aerobic-anaerobic digestion sequence. Another study was carried out to understand the nitrogen removal mechanism during aerobic digestion of anaerobic digested sludge. The feed sludge was spiked with four different concentrations of nitrate and nitrite. It was observed during the study that aerobic digestion of anaerobic sludge helps in achieving higher Volatile solid reduction (~65% vs ~ 46% for mesophilic digestion and ~52% for thermophilic digestion). This result supports the hypothesis concerning the different fractions in volatile solids. Experimental results also show that the increase in VSR upon increasing anaerobic digestion SRT (more than 15 days) is less than the increase in the VSR due to the same increment of aerobic digestion SRT. Reduction in COD and VFA were also measured to be more than 50% during aerobic digestion. Investigation of nitrogen fate during the sequential anaerobic-aerobic digestion show more than 50% total nitrogen removal. Higher nitrogen removal was in thermophilic anaerobic – aerobic digester combination than that in mesophilic anaerobic–aerobic combination. The most probable reason for the removal was simultaneous nitrification and denitrification. Higher concentration of readily available VFA from thermophilic anaerobic digested sludge provide advantage in denitrification in following aerobic digester. The resulting biosolids produced during sequential digestion process were also analyzed for dewatering properties and odor production. Proteins and polysaccharides concentrations were observed to decrease during aerobic digestion for thermophilic anaerobic - aerobic digestion combination, while in another combinations polysaccharide concentrations increases at aerobic phase with 3 day digestion. The concentration of polysaccharides decreases at higher digestion period of 6 and 9. The result of decrease in polysaccharide and protein was reflected by the reduction in the polymer dose consumption and decrease in the optimum CST for the biosolids resulting from the sequential anaerobic aerobic digestion. Experimental results from odor experiments show that odor production potential of the biosolids decreases with increase in both anaerobic phase SRT and aerobic phase SRT. Thermophilic biosolids produces comparatively low odors but for longer periods, while mesophilic biosolids produces higher magnitude of odors during storage but only for comparative shorter period. Aerobic digestion of anaerobic sludge helps in reducing more than 50% odor production, but freeze-thaw cycle experiment shows that in both anaerobic and sequential anaerobic – aerobic digested sludges have higher potential for odor production. Higher aerobic digestion SRTs (6 days and above) shows more potential of reducing odors, but more experimental work is required to be done. / Master of Science

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Generation of hydrogen sulfide (H2S) is a common phenomenon from wastewater collection, transport, and treatment processes. Impacts of H2S emissions from wastewater include corrosion and reduction in the service life of wastewater infrastructure, odor nuisance in the community, and health impacts on wastewater operations and maintenance personnel (Neilsen, et al. WEFTEC 2006). Conventional odor control studies performed by municipalities to design their individual odor/corrosion control strategies largely depend on establishing a dilution to detection threshold (D/T) ratio and ascertaining the recognition threshold (R/T) for air samples collected from the study area. These conventional odor studies based on grab samples using R/T and D/T technique using a few days of data have a number of limitations and potentially lead to inaccurate conclusions. However, H2S emission studies using continuous air monitoring is expensive and time consuming. The objective of this research is to understand the feasibility of utilizing emission factors as a tool to predict hydrogen sulfide emissions from headworks of four different Jefferson Parish, Louisiana wastewater treatment plants (WWTP). Proposed model(s) developed for predicting H2S emission factors that depend on wastewater parameters should be convenient for the municipalities to use as the data required is monitored routinely. Use of H2S emission models should assist rapid identification of H2S emission hot spots, optimize H2S control strategies, predict potential health risks, prevent community odor nuisance, and ascertain infrastructure corrosion. This dissertation attempts to; i) develop a research methodology, ii) identify instruments required, iii) generate emission factor ranges and compare their sensitivity to wastewater parameters, iv) generate preliminary empirical emission models based on flow treated, population serviced and area served by a treatment plant for each sampling location and v) provide a roadmap for future research opportunities to refine the models generated as part of this dissertation. Key words: emission model, emission factor, emission ranges, hydrogen sulfide, odor control, air quality, wastewater treatment.

Hydrogen Sulfide is a corrosive, odorous, and hazardous gas that can cause issues for wastewater collection systems and treatment plants. When evaluating hydrogen sulfide concentrations it is important to consider the source, odor causing mechanism, and its level of toxicity. In this study, continuous hydrogen sulfide monitoring was performed for 8 locations within the New Orleans East Bank Wastewater Treatment Plant for a span of 5 months. Hot spots within the plant are located and data analysis is performed based on daily and hourly averages of hydrogen sulfide concentrations. The data was configured to show peak hydrogen sulfide concentrations at specific time intervals throughout the day.

One of the factors recognized as affecting the dispersion of landfill odors off-site are complex meteorological conditions. A major issue is lack of consistent means to identify the odors and their intensity. The aim of this research was to investigate the influence of meteorological parameters (temperature, humidity, pressure, wind direction, wind speed, precipitation accumulation and weather conditions) on the frequency of odor complaints from nearby neighborhoods. Methods involved collection of ten years of data on odor complaints and weather conditions to determine if there were commonalities. Sophisticated statistical analyses employed did not reveal any relationships between odor complaints and weather alone. Need for substantial improvement of detailed information is recognized. To help identify the factors that influence odor complaints- a revised odor complaint form, along with operational adjustments, were recommended. An “Odor Threat Assessment Level” is proposed to assist landfill site personnel in managing daily operations, based on weather conditions. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Thesis (MTech (Environmental Management))--Cape Peninsula University of Technology, 2017. / ¹Odour nuisance is increasingly becoming one of the major environmental problems in various countries across the world, especially odour associated with wastewater (Alfonsin et al., 2015; Schlegelmilch et al., 2005; Gostelow et al., 2001). As a result, the management of odour from Wastewater Treatment Works (WWTW) has become one of the environmental challenges besetting these facilities in recent times. The dispersion of odour across the physical boundary of wastewater treatment facilities presents not only negative environmental impacts to the natural environment, but also constitute a nuisance to surrounding populations. The Athlone (WWTW) located in the urban City of Cape Town with high demographics and adjacent to sensitive communities is thus not immune to poor air quality associated with WWTW activities (Walton, 2005). The population growth due to rural-urban migration has further put severe pressure on the facility and thus worsening the odour problem in the area. As a result, complaints have been received by the City Council from the surrounding communities over the last 20 years. In response to these complaints, the management of the WWTW introduced an odour management system with a particular focus on the use of a biotrickling filter coupled with the use of odour masking sprays. This management intervention was adopted in order to control the odour emitted to the atmosphere from the facility (WWTW). While these measures are said to reduce the prevalence of odour to the surrounding environment, it was, however, not clear whether or not such management interventions have reduced odour emitted from the treatment plant. This research was premised on two postulations as an approach to analyse the effect of the odour management plan adopted by the Athlone WWTW’s management and these are: 1) the perceived experience of odour by the adjacent neighbouring communities and, 2) the understanding of the inherent atmospheric dynamics (such as wind velocity, atmospheric stability, inversion layer and ventilation) which influence odour dispersal in the area. The research project argues that these two factors should be taken into account to ensure that the management of odour is sustainable. It is within this background that the research aimed at assessing the management of odour at the Athlone WWTW and to find out, if at all, the inherent local atmospheric conditions in the area and views of the surrounding communities are incorporated into the management of odour from the plant. The methodological design adopted in the study was case study approach. However, the atmospheric data (wind speed and direction) was obtained from the South African Weather Service (SAWS). These variables were analysed qualitatively and experimentally by the use of wind diagrams to provide insight on 2atmospheric stability conditions, surface inversion and topographical properties, and how these phenomenon influences odour dispersion. The study also reviewed previous odour management reports produced by the Althone WWTW management. This type of data was finally supported by data collected from the community by means of a community survey, face-to-face in-depth interviews and qualitative observation. Some major findings from the study revealed that the local weather of Athlone influences the dispersion of odour – facilitating dispersion in the summer through high wind velocities, while impeding dispersion during winter due to the presence of atmospheric stability conditions. Prevailing odours in this community has led to a general feeling of displeasure amongst community members especially since the management of the treatment plan does not include the local community in the decision-making process. In spite of these, the facility’s management approach was found to be more of a response driven nature even though it is ranked as a high-risk facility.