Photosynthetic sediment microbial fuel cell (PSMFC) is a novel approach of sediment microbial fuel cells (SMFC) that provides oxygen as an electron acceptor in cathode without the need for mechanical aeration. An obstacle to these systems is instability and fluctuation in electricity production. In this study, PSMFCs catholytes were treated by adding carbon sources (bicarbonate/acetate) to algal catholyte and controlling pH of suspension using citric acid. These cells were also compared with an SMFC with aeration of cathodic compartment to investigate the effect of algal photosynthesis on production of oxygen for cathodic reactions. Voltage production, cathode potential, and dissolved oxygen were monitored daily and results demonstrated that controlling catholyte pH by citric acid was the most effective way of improving durability and electricity production of PSMFCs. Maximum stable voltage of cells treated with citric acid, acetate, and bicarbonate were 242.3 5.0 mV, 180.313.9 mV and 156.112.8 mV, respectively. In addition, the PSMFC with citric acid treatment was the most durable and remained stable for a longer time without voltage drop (15 days). Dissolved oxygen measurement revealed a significant increase of available oxygen for cathodic reaction by using algal catholyte. These results demonstrate that using microalgae for producing oxygen in cathode can be a helpful way of reducing costs of mechanical aeration for SMFC startup as well as improving SMFC electricity generation.

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