Dye Concentration Influence on Biodecolourisation

The concentration of dye is constantly fluctuating in the effluent of textile finishing process operations. However, the higher concentrations can be lowered by using an equalisation tank. In order to study the effects of various dye concentrations on the ability of microorganisms to decolourise textile finishing wastewater, several batch plots of dye concentration reduction were obtained. An azo dye was used and the inoculum was biomass acclimated to the dye. The study showed dye concentration to be an influential variable in biodecolourisation rate. The decolourisation rate, as given by net dye concentration reduction at 24 hours, increased linearly with dye concentration until a peak was reached beyond which the rate remained almost constant. The concentration at peak level was found to be dependent on the inoculum size. Dye concentration in textile finishing wastewater was calculated to be in the range of 6 to 50 mg/l. For an initial biomass concentration of about 2000 mg/l, this study showed that wastewater containing less than 50 mg/l of the dye should be completely decolourised within 24 hours of batch treatment.