THE FATE OF PHARMECEUTICALS AND PERSONAL CARE PRODUCTS IN A WASTE WATER TREATMENT PLANT: IMPLICATIONS FOR DISCHARGE TO URBAN WATERS

A large suite of pharmaceutical and personal care products (PPCPs) and hormones are known to occur in urban waters. Although environmental concentrations are very low (ng/L level) exposure studies have led to the concern that the levels of pharmaceuticals and personal care products (PPCPs) and hormones discharged into the environment from wastewater treatment plants will negatively impact the surrounding aqueous ecosystems. In this study, the fate and occurrence of 57 PPCPs and hormones were evaluated in a conventional activated sludge basin. The goal of the study was to define the basic constants needed to model the movement of PPCPs through the activated sludge basin. These constants include hydrodynamic dispersivity, intrinsic biodegradation rate constants and sorption coefficients. These constants, combined with the advective velocity, are needed to model the expected residence time of PPCPs within, and the expected discharge levels from, the activated sludge basin. Forty-eight of the PPCPs were detected in the soluble form and 29 were detected sorbed to solids. Measured dispersivity values were 550 m²/hr. Pseudo first order biodegradation rates range from no detectable degradation within 12 hours to t_1/2 = 8 mins (K_bio = 2.92 Lg^-1hr^-1). Several biodegradable PPCPs stopped being degraded at low, yet notable, concentrations. Apparent sorption coefficients were defined, although desorption reactions were found to be slow with respect to the residence time in the basin. The results of this study provide a framework to evaluate the efficacy of conventional activated sludge treatment processes in the prevention of PPCP discharge into the environment.