Impact of partially submersed iron scraps in simultaneously sulfate and nitrate removal using sulfate-reducing bacteria

Abstract In this study, partially submerged iron scraps were allowed to react to the contaminants at the headspace air and liquid interface for pollutants removal in the serum bottle reactors. The experiments were conducted using Box–Behnken design of Response Surface Methodology in anaerobic batch reactors (120 ml) at different concentrations of sulfate (0.5, 1.75, 3 g/L), nitrate (0.25, 0.375, 0.5 g/L) and iron scraps (0, 0.125, 0.250 g/50 ml). The sulfate reducer enriched mixed culture was used for simultaneous removal of SO 4 2 − and NO 3 − . The highest sulfate removal of 49.37 % was achieved at 0 g/50 ml ISs, 3 g/L SO 4 − 2 , and 0.375 g/L NO 3 − . Even at a higher concentration of both SO 4 2 − (3 g/L) and NO 3 − (0.5 g/L), a significant SO 4 2 − removal of 44.65% was achieved at an iron concentration of 125mg/50ml accompanied with NO 3 − conversion. Both the lower and higher concentrations of iron scraps were showing effective interaction at higher SO 4 2 − and NO 3 − levels. The results of the confirmatory experiments with iron scraps of 0.039 g/50 ml with the desirability of 0.92 showed a maximum SO 4 2 − removal of 50.62 % with complete conversion of nitrate.