Anaerobic biodegradation of triphenylmethane dyes in a hybrid UASFB reactor for wastewater remediation.

Anaerobic digestions have been proved more successful than aerobic systems for the degradation and destruction of dye-containing wastewaters. The performance of a hybrid up flow anaerobic sludge-filter bed (UASFB) reactor was tested with a synthetic wastewater containing Crystal violet (CV) as a carbon source and sodium acetate as a co-substrate. Continuous feeding of the reactor started with an initial OLR of 0.9 g COD/l-d and then it was increased step wise to 4 g COD l(-1) d(-1), while maintaining constant HRT (24 h). The optimum pH value and temperature for decolorization of crystal violet by this mixed culture species under anaerobic conditions were found to be 8-9 and 30-35°C respectively. N,N-dimethylaminophenol and N,N-bis (dimethylamino) benzophenone (Michler's Ketone) were detected as the degradative metabolites of Crystal Violet. Subsequently, N,N-dimethylaminophenol was further degraded to aniline in the reactor whereas Michler's ketone was not degraded under anaerobic conditions. The UASFB bioreactor was able to remove the CV completely up to a loading rate of 100 mg CV l(-1)d(-1).