Application of upflow constructed wetland microbial fuel cell for treating sewage spiked with reverse osmosis concentrate with the concomitant generation of green electricity

Over the past few decades, wastewater generation in India has increased rapidly owing to the population boom and industrial development, while the treatment capability in India stands only at around 33%. Hence, with the aim of developing sustainable decentralised technologies at a community level, the present study was conducted to showcase the treatment of two common domestic wastewater, namely, sewage and reverse osmosis (RO) concentrate via vertical up-flow constructed wetland microbial fuel cell (CW-MFC). The proposed setup will not only aid in reducing the volumetric load on centralised systems but also can produce utilisable bioelectricity. Two CW-MFCs [CW-MFC-1 (with plants), CW-MFC-2 (without plants)] were operated to observe the wastewater treatability by analysing various physico-chemical and electrochemical parameters. The maximum chemical oxygen demand (COD) removal efficiency of CW-MFC-1 (74.29 ± 2.45%) was approximately 14–18% higher than CW-MFC-2 (65.05 ± 2.00%) because of the presence of Canna indica, which contributed towards enhanced wastewater treatment for CW-MFC-1. Hence, the incorporation of C. indica favourably assisted in ameliorating the performance of CW-MFC-1. Also, the enrichment of the nutrients by supplementing RO concentrate majorly contributed to enhancing the electrochemical performance of both the systems. Moreover, the power densities in both the systems were almost comparable, 0.38 ± 0.05 W/m³ for CW-MFC-1 and 0.33 ± 0.04 W/m³ for CW-MFC-2. Thus, the present investigation exemplifies the successful treatment of RO concentrate mixed with sewage through upflow CW-MFC, which can be further used at the household level as a decentralised wastewater treatment system.