Improved power density and Cr/Pb removal using ozone in a microbial desalination cell

Microbial desalination cells are promising bio-electrochemical technologies for water desalination, treating wastewater and bioelectricity production. In this study, the capability of microbial desalination cell was investigated to remove chromium (Cr(VI)) and lead (Pb(II)), from industrial wastewaters. In addition, we tested the use of ozone as a new electron acceptor in microbial desalination cells to improve the removal efficiency and for bioelectricity generation. Findings were compared with those of another microbial desalination cell operated independently with oxygen: an O-2-microbial desalination cell. Results show that, to remove Cr using ozone, the maximum power density was 812mWcm(-2) and the removal efficiency was 99.2%. By comparison, for Cr when oxygenwas used, the maximum power density and removal efficiencywere lower, 354mWcm(-2), and 91.8%, respectively. For Pb using ozone, the maximum power density was 568mWcm(-2) and the removal efficiency was 98.4%. By comparison, for Pb using oxygen, the maximum power density was lower, of 232mWcm(-2), and the removal efficiency was also lower, of 88.5%. More stable current profiles were observed using ozone. Scanning electron microscopy images indicate that the whole surface of the anode is occupied by a complex dense biofilm. Overall, our findings show that modifying the bio-electrochemical processes with ozone promotes the reactorefficacy in terms of power generation and wastewater treatment.