Constructed wetlands operated as bioelectrochemical systems for the removal of organic micropollutants

TL;DR

This study investigates the effectiveness of constructed wetlands operated as bioelectrochemical systems in removing organic micropollutants from real urban wastewater, finding limited significant improvements over conventional systems.

Contribution

It provides experimental data on CW-BES performance with real wastewater, highlighting differences from laboratory results and assessing removal efficiencies of specific pharmaceuticals.

Findings

CW-BES showed slight, non-significant improvements in pollutant removal.

Real wastewater experiments differ from controlled lab results.

No statistically significant enhancement in removal efficiency was observed.

Abstract

The removal of organic micropollutants (OMPs) has been investigated in constructed wetlands (CWs) operated as bioelectrochemical systems (BES). The operation of CWs as BES (CW-BES), either in the form of microbial fuel cells (MFC) or microbial electrolysis cells (MEC), has only been investigated in recent years. The presented experiment used CW meso-scale systems applying a realistic horizontal flow regime and continuous feeding of real urban wastewater spiked with four OMPs (pharmaceuticals), namely carbamazepine (CBZ), diclofenac (DCF), ibuprofen (IBU) and naproxen (NPX). The study evaluated the removal efficiency of conventional CW systems (CW-control) as well as CW systems operated as closed-circuit MFCs (CW-MFCs) and MECs (CW-MECs). Although a few positive trends were identified for the CW-BES compared to the CW-control (higher average CBZ, DCF and NPX removal by 10-17% in CW-MEC and 5% in CW-MFC), these proved to be not statistically significantly different. Mesoscale experiments with real wastewater could thus not confirm earlier positive effects of CW-BES found under strictly controlled laboratory conditions with synthetic wastewaters.