Abstract
Greywater reuse through decentralized and low-cost treatment systems emerges as an opportunity to tackle the existing demand for water. In recent years, constructed wetlands (CW) systems and microbial fuel cells (MFCs) have emerged as attractive technologies for sustainable wastewater treatment. In this study, constructed wetland microbial fuel cells (CW-MFCs) planted with Phragmites australis were tested to evaluate the potential of combining these two systems for synthetic greywater treatment and energy recovery. Open (CW) and closed circuit (CW-MFCs) reactors were operated for 152 days to evaluate the effect of energy recovery on the removal of soluble chemical oxygen demand (sCOD), nutrients and total suspended solids (TSS). Results indicate no significant differences for sCOD and phosphate removal efficiencies. CW-MFCs and CW reactors presented sCOD removal efficiency of 91.7 ± 5.1% and 90 ± 10% and phosphate removal efficiencies of 56.3 ± 4.4% and 61.5 ± 3.5%, respectively. Nitrate removal efficiencies were higher in CW: 99.5 ± 1% versus 86.5 ± 7.1% in CW-MFCs, respectively. Energy generation reached a maximum power density of 33.52 ± 7.87 mW m−3 and 719.57 ± 67.67 mW m−3 at a poised anode potential of −150 mV vs. Ag/AgCl. Thus, our results suggest that the incorporation of MFC systems into constructed wetlands does allow energy recovery while providing effective greywater treatment.
Highlights
Water is a critical resource that is required for food production, energy generation, and industrial processes among other applications
Both constructed wetlands (CW) and CW-microbial fuel cells (MFCs) systems were highly effective in the removal of soluble chemical oxygen demand (sCOD), and significant sCOD
A quick decrease in sCOD levels was observed in both systems during the first six days each cycle
Summary
Water is a critical resource that is required for food production, energy generation, and industrial processes among other applications. Extreme weather due to climate change is projected to affect the availability and quality of water [1]. For this reason, the efficient use and management of water resources, including water reuse, is necessary. Greywater is a promising resource, accounting for. 50–80% of sewage [2], which could be treated for reuse in green areas or used as wash water [3]. Chemical, and biological technologies are used for greywater treatment. Among several biological treatments, constructed wetlands have been considered the most cost-effective and environmentally friendly technology used for this purpose [2]
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