Evaluation of a model for the removal of pharmaceuticals, personal care products, and hormones from wastewater

Abstract

Current wastewater treatment processes are insufficient at removing many pharmaceutical and personal care products (PPCPs) from wastewater and it is necessary to identify the chemical characteristics that determine their fate. Models that predict the fate of various chemicals lack verification using in situ data, particularly for PPCPs. BIOWIN4 is a quantitative structure-activity relationship (QSAR) model that has been proposed to estimate the removal of PPCPs from wastewater, but data verifying the accuracy of its predictions is limited. In this study, the in situ soluble and suspended solid concentrations were assessed from raw influent, primary effluent, secondary effluent, and final effluent for 54 PPCPs and hormones over six dates. When assessing the removal efficiency across the different stages of the WWTP, the majority of the removal occurred across the secondary treatment process for the majority of the compounds. The primary treatment and disinfection process had limited impacts on the removal of most PPCPs. Sorption to solids was found to influence the removal for compounds with a log octanol-water partitioning coefficient greater than 4.5 across the secondary treatment process. For other compounds, the removal of PPCPs across the secondary treatment process was significantly correlated with the biodegradation predicted by BIOWIN4. Removal efficiencies across the aerobic secondary treatment process were predicted by integrating BIOWIN4 into pseudo-first order kinetics of PPCPs and these predicted values were compared to the in situ data. This study determines that under a certain set of operating conditions, two chemical characteristics - the expected hydrophobic interaction and the modeled biological degradation from BIOWIN4 - were found to predict the removal of highly degradable and recalcitrant PPCPs from a wastewater secondary treatment process.