9613258 Watts Physicochemical processes that can enhance the biodegradability of biorefractory organic compounds in process water can serve as a basis for waste reduction, toxicity reduction, and water conservation through the recycling. The proposed research investigates coexisting chemical and biological oxidations in hybrid advanced oxidation process (AOP)-biological systems. The AOP is an iron oxyhydroxide-catalyzed Fentonlike reaction in which hydroxyl radicals are generated by heterogeneous catalysis at the mineral surface. Abiotic-biotic systems containing low microbial numbers may be dominated by Fenton-like oxidations. Conversely, systems with high biomass would likely be characterized by fewer Fenton-like oxidations because the hydrogen peroxide would be decomposed by catalase. However, under optimal proportions of abiotic and biotic mechanisms, hydroxyl radicals generated in a microenvironment at the mineral surface would modify biorefractory compounds and subsequent transformation of the oxidation products would then be promoted by a coexisting consortium of aerobic bacteria. Perchloroethylene will be used as a hydroxyl radical probe. 13C- labeled pyruvate will be used to assay microbial metabolism. A series of experiments will investigate interactions of biomass, hydrogen peroxide concentration, iron oxyhydroxide mineral concentration, and phosphate stabilization of hydrogen peroxide in promoting parallel abiotic-biotic oxidations. Transformation reactions will be confirmed by monitoring 14C-labeled perchloroethylene; degradation products will be tracked by gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry of 13C- labeled perchloroethylene to differentiate its products from the mass spectra of natural organic compounds. The results will provide fundamental data that can be applied to on site hybrid abiotic-biotic systems. ***
