Influence of supplemental nutrient on aerobic decolorization of acid red 14 in activated sludge

Azo dyes are non-biodegradable in the textile effluent under aerobic condition. This study demonstrates that the addition of nutrients leads to degradation of a selected azo dye (AR14), and the major decolorization kinetic pathway of AR14 could be expressed as a pseudo first order kinetic model under the experimental conditions used in this study. An excellent correlation was obtained between the decolorization speed and additional nutrient concentration, as indicated by a coefficient of determination (r2) of 0.9899. At a higher nutrient concentration, the relatively high color removal rate can be reached up to 92.9% in a short time. The degradation ability of azodye could be changed by supplemental nutrient. The destroy of chromophore was the first step of degradation of azo dye under the aerobic conditions, and the intermediates of the dye had significant toxic to the activated sludge, while AR14 of 150 mg/l had slight inhibitory effect on sludge respiration.