Diclofenac and carbamazepine removal from domestic wastewater using a Constructed Wetland-Solar Photo-Fenton coupled system

Abstract

The presence of pharmaceutical compounds in aquatic ecosystems may affect both biota and human health because these micropollutants are capable of altering the metabolism and reproduction capacity of the live organisms of the aquatic ecosystems. The main route of entry of these pollutants into the aquatic environment is through Wastewater Treatment Plants (WWTPs) effluents. Compounds such as diclofenac (DCF) and carbamazepine (CBZ) persist, undergoing little or no degradation during treatment. Coupled systems combining biological treatments and Advanced Oxidation Technologies (AOTs) represent an alternative to reduce the risk of the presence of pharmaceuticals in the environment by achieving high removal efficiency at a low cost. This research evaluated the performance of a coupled system integrated by Horizontal Subsurface Flow Constructed Wetland (CW HSSF) and Solar Photo-Fenton at laboratory scale under America tropical conditions for the removal of DCF and CBZ from domestic wastewater at 15 μg L−1, on average. Three Fe2 +/H2O2 ratios (0.1, 0.3, and 0.8) were tested. Concentrations of DCF, CBZ, organic matter (DOC), Total Nitrogen (TN), and in situ variables were measured throughout the experiment.Removal efficiencies up to 92% and 86% were achieved for DCF and CBZ, respectively, using the Fe2+/H2O2 ratio of 0.1. There were no significant differences between the Fe2+/H2O2 ratios used (p < .05), but significantly greater efficiencies were achieved when CW was coupled with solar Photo-Fenton (40% only CW and 92% coupled system). Additionally, the coupled system showed a removal efficiency of organic matter (DOC) and total nitrogen (TN) greater than 61%. The concentration of DOC and TN, pH, solar UV radiation, and peroxide consumption had no significant effect on the removal efficiency of DCF and CBZ.