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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

SMALL DECENTRALIZED AUTOTHERMAL THERMOPHILIC AEROBIC DIGESTION FOR PATHOGEN REDUCTION

Mottola-Lugo, Luciana 01 December 2012 (has links)
The current research relates to a system driven by renewable energy and chemical energy contained in the feed, which will eliminate and reduce pathogens found in human excreta. A project in the form of an experiment for demonstration will be designed and built to operate in the local waste water treatment plant. Data will be analyzed and recorded, including fecal coliforms and E.coli levels, chemical oxygen demand (COD) and total solids removal (TS). The effectiveness of the system will depend upon results obtained and weather conditions. The principal objective of the research is to test and demonstrate that the "Small Decentralized ATAD" is successful in removing/eliminating enteric pathogens found in human excreta. Most importantly, the Bill and Melinda Gates Charity Foundation is providing financial support (Grants) for new sanitation ideas to help developing countries overcome diseases, specifically water borne diseases and also diseases related to hygiene and sanitation. Moreover, the "Water, Sanitation & Hygiene: Grand Challenges Explorations" granted a $100,000 Grant to Professor James Blackburn from Southern Illinois University at Carbondale in the Mechanical Engineering and Energy Processes Department. Consequently, the "Decentralized Next Generation for Diarrheal Pathogens" project will be tested using the ATAD (Autothermal Thermophilic Aerobic Digestion) to demonstrate its effectiveness in pathogen reduction and elimination.
2

Effects of Solids Retention Time and Feeding Frequency on Performance and Pathogen Fate in Semi-continuous Mesophilic Anaerobic Digesters

Manser, Nathan Daniel 01 January 2015 (has links)
Anaerobic digestion is a biochemical process in which organic carbon is biodegraded in an oxygen free environment through a microbial consortium. Engineered biological systems used for resource recovery often utilize anaerobic digestion to treat anthropogenic organic wastes by reclaiming the carbon as energy (methane gas) and a soil amendment (biosolids). Small-scale, or household, semi-continuous anaerobic digesters have been used in developed and developing countries for many decades to produce biogas from human and livestock waste, which is used for heating, lighting, and cooking. This application has been shown to improve the quality of life of the user. Although there is great potential for small-scale semi-continuous anaerobic digestion to provide much needed resource recovery functions and quality of life improvements in future development, the manner in which these systems are operated could lead to unintended consequences on human health because human waste often contains resistant pathogens. This paradigm is best demonstrated by soil-transmitted helminths that are known to be highly resilient in mesophilic anaerobic digestion environments and endemic to many developing countries. The idea that soil-transmitted helminths survive mesophilic anaerobic digestion is exacerbated when the biosolids from the digesters are land applied as a soil-amendment because this process fits perfectly into the lifecycle of soil-transmitted helminths that need soil environments to develop into infective larva. This research was divided into three sections to investigate the fate of human pathogens during semi-continuous anaerobic digestion and investigate techniques to enhance their removal. The sections were: 1) an examination into the fate (embryonation, development, inactivation, destruction) of Ascaris suum ova during mesophilic semi-continuous anaerobic digestion, with an emphasis on increased inactivation, 2) an investigation into the performance (volatile solids (VS) removal, E. coli and Salmonella destruction, methane production) of semi-continuous mesophilic anaerobic digesters and the effect of variations to solids retention time (SRT) and feeding frequency, and 3) development and application of mathematical models for pathogen inactivation kinetics and typical semi-continuous reactor residence time distributions to predict the removal efficiency of Ascaris suum ova during semi-continuous anaerobic digestion under different operating conditions. Results of these studies showed that during semi-continuous mesophilic anaerobic digestion variations in feeding frequency did not impact the fate of Ascaris suum ova or Salmonella; however it was observed that better removal of E. coli and higher methane production was achieved at the longer feeding interval (weekly). Additional results indicated that embryonated ova were destroyed faster than unembryonated ova under the experimental conditions, which suggests a potential mechanism to enhance removal of this common pathogen. Since an increased feeding interval proved to be beneficial for digester performance our findings suggest that wastes containing Ascaris suum ova could be stored in an aerated environment, for a period of time that does not negatively impact resource recovery, to lengthen the time between feedings and promote ova embryonation and ensuing destruction during digestion. Modeling results indicate that under mesophilic conditions (35oC) the ova of Ascaris suum could survive for 22 days and will not be completely removed from the effluent under typical feeding frequencies and average SRT were examined. Therefore, the use of anaerobic digestion as a resource recovery technology where soil-transmitted helminths proliferate should be applied with extra operational safeguards or be included as one step of several in a small-scale treatment train.
3

Comparison of Bacterial and Viral Reduction Across Different Wastewater Treatment Processes

Vagadia, Aayushi R. 01 November 2018 (has links)
Today billions of people live without access to basic sanitation facilities, and thousands die every week due to diseases caused by fecal contamination associated with improper sanitation. It has thus become crucial for decision makers to have access to relevant and sufficient data to implement appropriate solutions to these problems. The Global Water Pathogen Project http://www.waterpathogens.org/ is dedicated to providing an up-to-date source of data on pathogen reduction associated with different sanitation technologies that are important if the world is to achieve the Sustainable Development Goals (SDGs) related to health and sanitation provision. In this research, a subset of the Global Water Pathogen Project (GWPP) data is used to access the reduction of bacteria and viruses across different mechanical and natural sanitation technologies. The order of expected removal for bacteria during wastewater treatment was reported as highest for a membrane bioreactor (4.4 log10), waste stabilization pond (2.3 log10), conventional activated sludge (1.43 log10), anaerobic anoxic oxic activated sludge (1.9 log10), trickling filter (1.16 log10), and upflow anaerobic sludge blanket reactor (1.2 log10). Furthermore, the order of expected removal for viruses was reported as highest for a membrane bioreactor (3.3 log10), conventional activated sludge (1.84 log10), anaerobic anoxic oxic activated sludge (1.67 log10), waste stabilization pond (1 log10), upflow anaerobic sludge blanket reactor (0.3 log10) and trickling filter (0.29 log10). It was found that hydraulic retention time (HRT) had a statistically significant relation to the reduction of bacteria in an anaerobic, anoxic oxic treatment system. Similarly, a significant relation was found between the number of waste stabilization ponds in series and the expected reduction of bacteria. HRT was also found to be a significant factor in virus reduction in waste stabilization ponds. Additionally, it was observed that waste stabilization ponds, trickling filters, and UASB reactors could obtain a greater reduction in bacteria (5-7 log10) when combined with additional treatment (e.g., chemical disinfection or use of maturation ponds). Also, mechanized systems, such as activated sludge systems and membrane bioreactors, obtained a greater reduction (2-3 log10) of viruses when compared to a natural system. It was concluded that the selection of the best suitable technology for pathogen reduction depends on environmental, design, and operational factors as well as considering the performance of specific wastewater treatment systems individually as well as when combined with other treatment technologies that may provide added removal of microbial constituents.
4

Designing Smarter Stormwater Systems at Multiple Scales with Transit Time Distribution Theory and Real-Time Control

Parker, Emily Ann 17 June 2021 (has links)
Urban stormwater runoff is both an environmental threat and a valuable water resource. This dissertation explores the use of two stormwater management strategies, namely green stormwater infrastructure and stormwater real-time control (RTC), for capturing and treating urban stormwater runoff. Chapter 2 focuses on clean bed filtration theory and its application to fecal indicator bacteria removal in experimental laboratory-scale biofilters. This analysis is a significant step forward in our understanding of how physicochemical theories can be melded with hydrology, engineering design, and ecology to improve the water quality benefits of green infrastructure. Chapter 3 focuses on the novel application of unsteady transit time distribution (TTD) theory to solute transport in a field-scale biofilter. TTD theory closely reproduces experimental bromide breakthrough concentrations, provided that lateral exchange with the surrounding soil is accounted for. TTD theory also provides insight into how changing distributions of water age in biofilter storage and outflow affect key stormwater management endpoints, such as biofilter pollutant treatment credit. Chapter 4 focuses on stormwater RTC and its potential for improving runoff capture and water supply in areas with Mediterranean climates. We find that the addition of RTC increases the percent of runoff captured, but does not increase the percent of water demand satisfied. Our results suggest that stormwater RTC systems need to be implemented in conjunction with context-specific solutions (such as spreading basins for groundwater recharge) to reliably augment urban water supply in areas with uneven precipitation. Through a combination of modeling and experimental studies at a range of scales, this dissertation lays the foundation for future integration of TTD theory with RTC to improve regional stormwater management. / Doctor of Philosophy / Urban stormwater runoff contains a variety of pollutants. Conventional storm drain systems are designed to move stormwater as quickly as possible away from cities, delivering polluted runoff to local streams, rivers, and the coastal ocean – and discarding a valuable freshwater resource. By contrast, green stormwater infrastructure captures and retains stormwater as close as possible to where the rain falls. Green stormwater infrastructure can also help remove pollutants from stormwater through physical, chemical, and biological treatment processes. This dissertation describes two modeling approaches for understanding and predicting pollutant removal processes in green stormwater infrastructure (Chapters 2 and 3). Chapter 4 explores the implementation of smart stormwater systems, which use automated controllers and sensors to adaptively address stormwater management challenges. Through a combination of modeling and experimental studies at a range of scales, this dissertation lays the foundation for future improvements to regional stormwater management.
5

Wastewater Reuse: Comprehensive Study about Treatment System Efficiency and Potential Public Health Concerns

Park, Eunyoung January 2015 (has links)
No description available.

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