Biodegradation and Chemical Oxidation of Recalcitrant Organic Contaminants during Water Reuse
Civil and Environmental Engineering
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Water reuse of municipal wastewater effluent has become a potential solution for water shortages in arid regions that stem from the growth of human populations and effects of global climate change. However, municipal wastewater effluent contains many organic contaminants in trace quantities, which pose potential risks for human health and environmental systems. Pharmaceuticals and personal care products (PPCPs) are one example of trace contaminants that are usually found in treated municipal wastewater. Batch biodegradations studies were performed to measure the degradation of selected PPCPs in water-soil systems. The selected PPCPs analyzed in this study represent major pharmacological classes and personal care products frequently detected in secondary-treated municipal wastewater effluent. Wastewater effluent was collected from Truckee Meadows Water Reclamation Facility (TMWRF) and concentrated to evaluate the effect of organic carbon concentration on PPCP degradation. Biodegradable dissolved organic carbon (BDOC) acts as a main carbon source for microbes and is considered as one of important factors that would affect the biodegradation rates of PPCPs. Wastewater samples containing different concentrations of BDOC were spiked with select PPCPs and concentrations were monitored in two batch trials over a 60 day period. The experiments demonstrated that PPCPs had higher removal rates at low BDOC concentrations. The objective of Mn(VII) studies is to estimate the reaction rate of Permanganate (Mn(VII)) with PPCPs. Mn(VII) is a strong oxidant and was evaluated in this study as another potential degradation method for PPCPs. The reaction rates between Mn(VII) and PPCPs were measured by both spectrophotometric and high performance liquid chromatography (HPLC) methods. Total organic carbon (TOC) in wastewater was competing with PPCPs to react with Mn(VII). PPCPs did exhibit higher removal efficiency using Mn(VII) oxidation as compared to observed biodegradation rates in the batch studies, although the oxidation rate of PPCPs by Mn(VII) in natural water system is still uncertain.