Combination of Microbial Fuel Cells with Microalgae Cultivation for Bioelectricity Generation and Domestic Wastewater Treatment

A microbial fuel cell (MFC) is a device that uses bacteria as catalysts to oxidize organic matters as well as generate electrical current. MFCs are effective in chemical oxygen demand (COD) removal from wastewater; however, MFC alone is not effective in nitrogen and phosphorus removal. Alternatively, microalgae can effectively remove nitrogen and phosphorus from wastewater. To improve treatment efficiency of wastewater, a combined process consisting of MFC and microalgae cultivation was developed, and the effectiveness of the system for wastewater treatment and electricity generation was evaluated. Wastewater was first treated with a single-chamber MFC (SMFC) for removing COD, and partial removal of nitrogen and phosphorus accompanied with electricity generation; then, the treated wastewater was used to cultivate microalgae to further remove the residual phosphorus and nitrogen. The SMFC generated a maximum power density of 268.5 mW/m2 and achieved 67% COD removal; only 34% total phosphorus (TP) and 50% NH4+-N removal were obtained with SMFC alone. Up to 97% TP and 99% NH4+-N removal were achieved with the combined process. These results demonstrated that the combined process was effective for wastewater treatment, resulting in improved TP and NH4+-N removal compared with MFC alone and providing a promising candidate for treating wastewater.