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 SO42− and NO3−. The highest sulfate removal of 49.37 % was achieved at 0 g/50 ml ISs, 3 g/L SO4−2, and 0.375 g/L NO3−. Even at a higher concentration of both SO42− (3 g/L) and NO3−(0.5 g/L), a significant SO42− removal of 44.65% was achieved at an iron concentration of 125mg/50ml accompanied with NO3− conversion. Both the lower and higher concentrations of iron scraps were showing effective interaction at higher SO42− and NO3− 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 SO42− removal of 50.62 % with complete conversion of nitrate.