Microbial Inactivation of Municipal Sludge Using E-Beam and Chemical Oxidants
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Municipal biosolids generated from waste water treatment plants should be effectively disinfected before being used for beneficial purposes. Novel sewage sludge treatment technologies ensuring efficient microbial inactivation and sludge stabilization can help in reducing adverse environmental and health impacts. The underlying hypothesis of this study was that electron beam irradiation solely, or in combination with chemical oxidants such as ferrate or chlorine dioxide, will effectively inactivate the microbial loads in municipal biosolids. The specific objectives of the research were to determine the inactivation of selected microbial pathogens and indicator organisms(Salmonella Typhimurium, Escherichia coli, phi X 174, MS2, poliovirus, Bacillus subtilis and Clostridium perfringens spores) using high energy (10 MeV) ebeam irradiation in the presence and absence of ferrate and or chlorine dioxide. Additionally, a quantitative microbial risk assessment (QMRA) exercise was performed to evaluate the risk reduction using e-beam technology. Results indicated that susceptibility of different target organisms to the e-beam irradiation varied considerably, with bacteria being most sensitive and bacterial endospores being most resistant in both aerobically and anaerobically treated sludge. Bacteria as well as poliovirus were susceptible to 200 ppm of ferrate. However, coliphages and endospores could be inactivated, only when ferrate was combined with ebeam. Somatic coliphage were susceptible 30 ppm of chlorine dioxide treatment, where as poliovirus and endospores were resistant to 30 ppm chlorine dioxide treatment. Microbial inactivation by e-beam and chemical oxidants depended upon the sludge matrix (aerobic and anaerobic).QMRA results indicate that the application of e-beam technology to sludge applied to lettuce growing field reduced the risk of food borne outbreaks to below detectable level. Overall, the results highlight the efficiency and stability of e-beam and chemical oxidants in ensuring sludge disinfection and safe nutrient recycling.
Vijayakumaran Nair Sobha, Chandn 1983- (2009). Microbial Inactivation of Municipal Sludge Using E-Beam and Chemical Oxidants. Master's thesis, Texas A&M University. Available electronically from