Occurrence and elimination of pharmaceutical residues in municipal wastewater effluent by electrochemical anodic oxidation

Abstract

Electrochemical advanced oxidation processes (eAOPs) have garnered significant attention as effective methods for eliminating trace organic pollutants from water. However, their practical application in treating actual waste streams has been limited. This study aimed to explore the potential of eAOP for the treatment of real effluents from a sewage treatment facility. Specifically, anodic oxidation using a Boron-doped diamond (BDD) electrode was utilized to treat secondary wastewater effluent (WWE) from a Dutch municipal wastewater treatment plant. To evaluate the occurrence of micropollutants and study their degradation, a suspect screening method involving ultra-high performance liquid chromatography (UHPLC) with tandem quadrupole time-of-flight mass spectrometry (QTOF-MS) was developed, resulting in the detection of 24 organic micropollutants in the WWE. The identity of 10 of these was confirmed with authentic standards, and their concentrations were determined using isotopically labeled standards. Subsequently, the simultaneous removal of these pharmaceuticals from ultrapure water (spiked with 25 μg/L of each drug) and real municipal WWE (actual concentration < 2 μg/L) by anodic oxidation with a BDD electrode was investigated. The effect of applied current and treatment time was examined and optimized, resulting in removal efficiencies >95 % for 9 out of 10 pharmaceuticals in municipal WWE after 20 min treatment at a current density of 24 mA/cm2.