Antimony removal from wastewater by sulfate-reducing bacteria in a bench-scale upflow anaerobic packed-bed reactor

摘要

The objective of this research was to study the precipitation of Sb and the stability of Sb2S3 during treatment of synthetic Sb(V)wastewater by sulfate-reducing bacteria(SRB).We investigated the transformation and precipitation of Sb,as well as the re-dissolution of Sb2S3 under different pH and carbon sources.The results showed that the precipitation of aqueous Sb and the re-dissolution of Sb2S3 depend on the conversion between Sb(Ⅲ)-S(-Ⅱ)complexes and Sb2S3 precipitates.These processes were highly pH-dependent,and a decrease in pH enhanced reduction of Sb(Ⅴ)and precipitation of Sb2S3 were observed.The newly formed Sb2S3 was found to be unstable and could re-dissolve through complexation with H2 S due to the increase in pH.When pH decreased to approximately 6.5,Sb was almost completely transformed into Sb2S3 precipitates,and the Sb2S3 precipitates were relatively stable.Compared with lactate as a carbon source,ethanol resulted in a comparable H2 S yield and a relatively low pH and was,therefore,more conducive to the removal of Sb(Ⅴ).The results of this study suggest that when removing Sb(Ⅴ)in wastewater by SRB,it is important to control the pH at a relatively low level.