Enhanced sulfide removal by gas stripping in a novel reactor for anaerobic wastewater treatment.

Removal of sulfide by gas stripping using biogas produced in an internal phase-separated reactor (IPSR) was evaluated during anaerobic treatment. The IPSR consisted of upper and lower segments with a gas-liquid partitioning (GLP) valve between the sections. Wastewater was fed to the upper segment in the first stage and then to the lower segment in the second stage. The GLP valve separated the liquid phase from the gaseous phase and supplied biogas from the lower segment to the upper segment. The IPSR and a control reactor were fed with synthetic wastewater and operated in parallel under an organic loading rate of 12 kg COD/(m3 day) at 35 °C. The sulfide concentration increased to 400-600 mg S/L, which is above the previously reported 50% inhibition level for methanogenic activity. The IPSR showed higher H2S removal performance than the control reactor and removed approximately twice the H2S as the control reactor at 400 mg S/L, indicating that it can be used for the stable treatment of wastewater containing high concentrations of sulfide.