Keywords: azo dye, mixed culture, RBC reactors, rotating biological contactor, textile wastewater, factorial design, decolourisation, synthetic wastewater, wastewater treatment, dye concentration, disc rotation speed, ANOVA
Decolourisation of azo dye containing synthetic wastewater in a rotating biological contactor reactor: a factorial design study
The effects of initial dye concentration and disc rotation speed were studied on the performance of a continuously operated rotating biological contactor (RBC) reactor in decolourising an azo dye containing synthetic wastewater, employing the statistically planned 2k full factorial design of experiments. While the initial dye concentration in the study varied between 50 mg/l and 100 mg/l, the disc rotation speed ranged from 5 rpm to 11 rpm. The RBC with a hydraulic retention time of two days showed steady state dye decolourisation efficiency of more than 92% in all the experimental runs. Statistical analyses in the form of Analysis of Variance (ANOVA) and significance test of factors revealed that the main effects of both the factors were highly significant (P < 0.05) on the performance of the RBC and the effect of initial dye concentration was, however, negative and more compared to that of the disc rotation speed.