Electro-Wetland Framework for wastewater Treatment: Advancing Energy-Positive environmental solutions

Abstract

Wastewater treatment with concurrent energy recovery plays a pivotal role in achieving sustainable development goals. Among emerging concerns, eutrophication remains a significant environmental threat, primarily driven by excess nutrient discharge into water bodies. Microbial fuel cells (MFCs) offer a promising solution by converting the chemical energy in organic matter directly into electricity. In this context, the present study investigates the integration of MFCs into constructed wetlands (CWs), resulting in Electro-Wetlands (EWs) hybrid systems engineered to achieve simultaneous nutrient removal and bioelectricity generation. Two identical CWs and EWs systems were designed and operated using institutional sewage to comparatively assess treatment efficiency and energy output. The EW units demonstrated enhanced nutrient removal (>90%) compared to CWs (75-85%), along with comparable fecal coliform reduction across both systems over a 60-day operational period. Hydraulic performance remained stable, with average evaporation rates of 0.99 L/day for EWs and 0.98 L/day for CWs, indicating minimal impact due to electrode integration. Electrochemical analysis of the EWs showed a consistent voltage output of 60-90 mV, current densities between 0.03-0.06 mA/cm(2), and power densities ranging from 1.5-3.0 mW/m(2), with peak values reaching 120 mV and 6 mW/m(2), respectively. The novelty of this study lies in the comparative evaluation of conventional CWs and Electro-Wetlands and the demonstration of a simple, cost-effective strategy for upgrading existing CWs to EWs with minimal structural changes. This makes the approach highly scalable and adaptable for decentralized wastewater treatment in institutional or community-based settings. Moreover, the study contributes to understanding the operational mechanism of CWs versus EWs, supporting future design improvements and broader implementation.