Treatment of Molasses-Alcoholic Wastewater via A Two-Stage Anaerobic Process Combined with Biological Desulfurization

Abstract:

The operation performance of a process including two-stage anaerobic digestion combined with biological desulfurization for treating molasses alcohol wastewater was evaluated during the startup and stable operation in this study. The results showed that when the COD and SO42- volume loading rate were improved to 15~21 kg/（m3·d） and 0.8~1.1 kg/（m3·d），the removal rate of COD and SO42- were up to 95%~96% and 86%~90%，respectively，and the content of COD，SO42- and sulfide in effluent were 6 000~6 500，800~850 and 750~800 mg/L，respectively. Especially，the contribution rates to the COD and SO42- remove efficiencies for the first stage and the second stage digestion were 86%，11% and 90%，7%，respectively，while both of them were about 3% in the biological desulfurization. Thus，the treatment efficiency of the first stage digestion was significantly higher than that of the second stage digestion. Furthermore，the sulfide remove rate was relatively low（about 30%） in the biological desulfurization process under high loading rate. Although it was possible to increase dissolved oxygen and relieve the adsorption of sulfur on the ceramic surface by improving aeration strength，the increasing aeration also affected the formation of biofilm and fixation of sulfur bacteria，which led to the loss of microorganisms. Hence，how to ensure mass transferring efficiently among the substrate，sulfur bacteria and oxygen was the key problem to be solved in the further research.