Effect of sulfate on anaerobic biodecolorization of azo dyes
硫酸盐在偶氮染料厌氧生物脱色中的作用

The effect of sulfate on anaerobic biodecolorization of Reactive Black 5(RB5) and Direct Yellow 11(DY11) by Rhodopseudomonas palustris W1 was investigated.Results showed that sulfate did not affect the decolorization process,whereas its reduction product,sulfide,greatly stimulated chemical decolorization of both of two dyes in the presence of redox mediators,which can be completed in 3 min.Without external supplement of redox mediators,RB5 decolorization can also be accelerated by sulfide with redox mediators from RB5 degrdation,however,no similar acceleration was observed in DY11 decolorization due to the lack of redox mediators production.Furthermore,elemental sulfur resulting from the oxidation of sulfide was biotransformed to sulfide again to reduce azo dyes repeatedly.