Treatment of a textile dye in the anaerobic baffled reactor

Synthetic organic colourants, the majority of which are recalcitrant in nature, are used in many different manufacturing processes. The dyes are released into the environment in industrial effluents and are highly visible even at low concentrations (< 1 mg/l). Decolorisation of the dye CI Reactive Red 141 was investigated in a laboratory-scale anaerobic baffled reactor (ABR). The results of the physical decolorisation tests suggested significant decolorisation due to adsorption to the biomass; however, it is possible that the dye chromophores were reduced due to the low redox potential environment within the test bottles. No dye breakthrough, due to adsorption saturation, was observed during operation of the reactor. COD reduction was consistently > 90 %. Colour reduction averaged 86 %. The biomass showed acclimation to the dye, with increased methanogenic activity with each increase in dye concentration. The reactor operation was stable, even with increases in the dye concentration. This investigation has shown that successful treatment of a highly coloured wastewater is possible in the ABR.