A pilot-scale study investigating the use of low-pressure, high-intensity UV radiation for disinfection of urban wastewater was conducted. The inactivation of coliform bacteria, wastewater-indigenous enteric viruses, seeded poliovirus, and seeded F-specific coliphage was studied. During the course of the pilot study, infectious human adenoviruses were isolated from 15 of 16 large-volume samples of UVdisinfected secondary-and tertiary-treated wastewater. Half of the tertiarytreated, UV-disinfected effluent samples from which the adenoviruses were isolated had total coliform concentrations that complied with California's Water Recycling Criteria. To determine the relative UV resistance of the adenovirus isolates, purified viruses were seeded into tertiary-treated wastewater and exposed to low-pressure, high-intensity, collimated UV radiation. A dose of approximately 170 mW-s/cm 2 was required to achieve 99.99% inactivation. These findings suggest that UV doses effective at meeting certain wastewater regulations for total coliform bacteria may not provide suitable inactivation of the UV-resistant human adenoviruses. Water Environ. Res., 75, 163 (2003).

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Full-scale operation of anaerobic codigestion of food waste with municipal sludge is viable, but it is still new. There is a lack of readily available scientific information on the quality of raw biogas, as well as on potential emissions from power generation using this biogas. This research developed scientific information with regard to quality and quantity of biogas from anaerobic co-digestion of food waste and municipal wastewater sludge, as well as impacts on air quality from biopower generation using this biogas. The need and performance of conditioning/pretreatment systems for biopower generation were also assessed.

A rapid and efficient treatment method, using periodate (PI) for sonochemical oxidation of persistent and bioaccumulative perfluorooctanoic acid (PFOA) was developed. With an addition of 45 mM PI, 96.5% of PFOA was decomposed with a defluorination efficiency of 95.7% after 120 min of ultrasound (US). The removals of PFOA were augmented with an increase in PI doses. In all the PI+US experimental runs, decomposition efficiencies were essentially similar to those of defluorination, indicating that PFOA was decomposed and mineralized into fluoride ions. Lower solution pHs resulted in an increase in decomposition and defluorination efficiencies of PFOA due to acid-catalyzation. Dissolved oxygen increased the amount of IO4 radicals produced, which consumed the more effective IO3 radicals. Consequently, presence of oxygen inhibited the destruction of PFOA. The PFOA degradation rates with different gases sparging are in the following order: nitrogen>air>oxygen. Effects of anions follow the Hofmeister effects on PFOA degradation (i.e., Br(-)>none ⩾ Cl(-)>SO4(2)(-)). Br(-) could react with OH to yield radical anion Br2(-) that enhances the PFOA degradation. A reaction pathway was also proposed to describe the PI oxidation of PFOA under US irradiation.

Microwave-hydrothermal treatment of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water with persulfate (S 2 O 2 -8 ) has been found effective. However, applications of this process to effectively remediate PFOA pollution require a better understanding on free-radical scavenging reactions that also take place. The objectives of this study were to investigate the effects of pH (pH = 2.5, 6.6, 8.8, and 10.5), chloride concentrations (0.01-0.15 mol$L -1 ), and temperature (60°C, 90°C, and 130°C) on persulfate oxidation of PFOA under microwave irradiation. Maximum PFOA degradation occurred at pH 2.5, while little or no degradation at pH 10.5. Lowering system pH resulted in an increase in PFOA degradation rate. Both high pH and chloride concentrations would result in more scavenging of sulfate free radicals and slow down PFOA degradation. When chloride concentrations were less than 0.04 mol$L -1 at 90°C and 0.06 mol$L -1 at 60°C, presence of chloride ions had insignificant impacts on PFOA degradation. However, beyond these concentration levels, PFOA degradation rates reduced significantly with an increase in chloride concentrations, especially under the higher temperature.

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