Sulfur oxidation process: A neglected contributor to minimize P release during sediment microbial fuel cell operation

Abstract

• SMFC was an effective approach to minimize P release to overlying water. • SMFC was conducted to study the effect of S oxidation on P release from sediment. • FeS of sediment was decreased and SO 4 2− of pore water was increased in SMFC group. • Sulfur-oxidizing bacteria were dominant in the SMFC group. • S oxidation process was a neglected contributor to minimizing P release with SMFC. In this study, long-term operation (300 days) of sediment microbial fuel cell (SMFC) was conducted to investigate the effect of sulfur oxidation on phosphorus (P) release from sediment. The result described that the released P to the water column of SMFC group was much lower during the whole operated time, suggesting SMFC was an effective approach to inhibit endogenous P release from sediment. FeS in the sediment was decreased in the vicinity of anode and SO 4 2− concentration was accumulated in the pore water from day 160 onward, suggesting the occurrence of FeS oxidation process. At the same time, part of dissolved Fe 2+ was upward-diffused and oxidized to Fe(III) oxides, followed by adsorption P, rendering higher BD-P buildup in the surface sediment (612.50 ± 32.25 μg/g). Further, the potential of sulfur-oxidizing bacteria, Tumebacillus (7.31%) and family Desulfobulbaceae (3.06%), were dominant, confirming bio-sulfur oxidation process in the SMFC group. In conclusion, sulfur oxidation process was a significant contributor to minimize P release from sediment in SMFC.