Effect of operating parameters on sulfide biotransformation to sulfur

A laboratory-scale bioreactor with polyethylene semi-soft packing was constructed and utilized to determine the efficiency of sulfide biotransformation to sulfur under various operating parameters. Sodium sulfide dissolved in tap water was pumped into the bioreactor as sulfide for biological desulfurization. The sulfide, sulfur and sulfate-S in the effluent and the sulfide purged as gas-phase H2S were determined to investigate the effects of operating parameters, such as pH, DO, hydraulic retention time (HRT), temperature and salinity, on the sulfide oxidation products. The activity of bacteria was highest at pH 7.8–8.2. The maximal sulfide removal load was 7.25 kg/(m3·day), with a 322.07 mg/L influent sulfide concentration and 4.80 mg/L DO. The increase of DO value corresponds to a decrease in the sulfur yield. The reactor had the highest sulfide removal load and sulfur yield at 2.55 mg/L DO. HRT had little effect on desulfurization efficiency when the sulfide removal load was kept constant. The most effective desulfurization temperature was 33°C. The sulfide removal load decreased from 2.85 to 0.51 kg/(m3·day) with increasing salinity from 0.5% to 2.5% (m/m).