Sulfur recovery in the sulfide-oxidizing membrane aerated biofilm reactor: experimental investigation and model simulation

The production of sulfur (S) from the biological oxidization of sulfide (S²⁻) by SOB (sulfide-oxidizing bacteria) allows for resource recovery. Past researches have indicated that S recovery from S²⁻ oxidation MABR (the membrane aerated biofilm reactor) was feasible. The process was complicated by the requirement of maintaining appropriate oxygen supply to prevent the produced S from being further oxidized into sulfate ($4_{2-}^{}$) and by the presence of heterotrophic biomass. In this study, a multispecies biofilm model was developed and experimentally validated to gain insight for the S recovery process in MABR. The developed model was capable of predicting the S recovery performance in the MABR. The optimal conditions involved in maintaining the appropriate oxygen flux and the biofilm thickness according to the hydraulic and S²⁻ loading rate. The low anoxic heterotrophic growth rate using $4_{2-}^{}$ and S as electron donors could explain why the impact of heterotrophic growth was insignificant.