Simulation experiment and kinetic investigation on biological sulfide removal process for wastewater treatment in high-sulfur gas reservoir

In this article, beneficial bacteria were employed in a self-designed sequential batch reactor (SBR) to oxidize and remove sulfide in wastewater of high-sulfur gas reservoir for the first time. The technical feasibility of this novel approach using biochemical reaction system was verified, and sensitivity experiments were conducted to evaluate the effects of several key technological parameters on sulfide removal performance. The sulfide removal kinetics were characterized, and corresponding mechanisms were figured out through in-depth analysis of biochemical reaction pathway, enzyme system catalytic characteristic and electron transport model in terms of microbiology and microscopic molecular structure. Results show that there are three major regions during the whole sulfide removal process defined as initial delay period (IDP), rapid desulfurization period (RDP), and final decline period (FDP). Geobacillus N411 is figured out to be an excellent candidate for sulfide removal in complex water environment with high sulfide and salinity load, which opens a completely new approach to effective treatment of wastewater for high-sulfur gas reservoir in natural gas industry . The optimal bacterial solution concentration is 6440 mg/L, slow stirring mode is recommended, the optimal environment temperature is 40 °C, and the optimal influent pH is 7.5. The zero-order kinetic model can describe the sulfide removal process well, and environmental temperature is found to be the most important technological parameter. Biological sulfide removal involves multiple sequential stages, following the oxidation pathway S 2− → S 0 → SO 3 2− → SO 4 2− . Once the technological parameters deviate from the optimal value, the cluster structure of enzyme protein would be disrupted, resulting in weaken or even loss of catalytic ability. • Beneficial bacteria were employed to remove sulfide in wastewater of high-sulfur gas reservoir for the first time. • The technical feasibility of this novel approach using biochemical reaction system was verified. • Sensitivity experiments were conducted and the optimal parameters were figured out. • Kinetic calculation was possessed by exponential model for biological sulfide removal process. • The kinetic analysis brings new microscopic insights into the biochemical reaction mechanism.