Benzene Biodegradation under Anaerobic Conditions Coupled with Metal Oxides Reduction

Anaerobic benzene biodegradation was performed in batch experiments using Rhine River sediment as inoculum and amorphous Mn(IV) or Fe(III) as independent final electron acceptors. Benzene (4.5 μmol) was degraded in 80 and 710 days in batch experiments under Mn(IV) and Fe(III) reducing conditions, respectively. Highest benzene degradation rate, 0.07 μmol/day, was obtained under Mn (IV) reducing conditions, with soluble Mn(II) and CO2 recoveries of 71.5% and 93% regarding to the stoichiometric values, respectively. Likewise, benzene biodegradation was performed in a continuous column coupled to the reduction of Mn(IV). Efficiency of benzene biodegradation was up to 97% under steady state operation in a sediment column operated continuously for more than 160 days. The carbon dioxide and Mn(II) recoveries were 88% and 77%, respectively, of the theoretical ratio according to the stoichiometry for benzene biodegradation.