Synergism of hydrolytic acidification and sulfate reducing bacteria for acid production and desulfurization in the anaerobic baffled reactor: High sulfate sewage wastewater treatment

High sulfate concentrations in sewage wastewater restricts the application of treatment technologies. In this present study, acid production-sulfate reduction reaction system effectively improved the high concentration sulfate removal from the sewage wastewater. Acid-generating phase in the two-phase anaerobic process was used. After 33 days of low-load start-up, COD removal efficiency in the acid-producing phase reached > 40%. Effluent VFA stable around 1400 mg/L and pH 4.0 ∼ 4.3. Effluent alkalinity was continuously reduced until zero, acidogenic phase started successfully. In acid production-sulfate reduction reactor, when COD/SO42− 3, the hydrolytic acidification bacteria maintained stable hydrolysis acidification ability. Sulfate-reducing bacteria increased the degree of acidification by 10%∼15%. The metabolic rate of acid bacteria reflected the good synergistic effect. When hydraulic retention time was controlled at 8.5 h and influent COD 3000 mg/L, with the decrease of COD/SO42− ratio, effluent sulfate removal efficiency gradually decreased. For COD/SO42− 6, ABR reactor had obvious phase separation characteristics of acid production-sulfate reduction and methanogenic phase. With the decrease of COD/SO42−, SO42− removal affected each compartment (methanogenesis weakened). For COD/SO42− 3, the effluent sulfate removal efficiency decreased with the decrease in HRT. At HRT 8 h, the sulfate removal by ABR reactor mainly occurred in I compartment. As the HRT decreases, the compartment that takes the main sulfate removal gradually moves backwards. When the HRT was 2 h, the sulfate removal occurred mainly in the II and III compartments. This present study can effectively solve the contradictions and drawbacks in the traditional biological desulfurization process and improves the efficiency of biological desulfurization.