This study shows that, with the add

This study shows that, with the addition of some materials (including DEC and PAC) into the activated sludge system directly, color can be effectively removed from cotton textile industry wastewater. Other materials (i.e. bentonite, activated clay and Macrosorb) investigated in this study were found to be ineffective for color removal. With 120 mg/L DEC, 100 and 200 mg/L PAC addition into the activated sludge system color removal efficiencies were statistically similar. While the color removal efficiency was 78% for the addition of 120 mg/L DEC, it was 77% for the addition of 200 mg/L PAC. The TSS concentration did not increase with DEC addition. However, a significant increase in TSS concentration was observed for PAC addition. From the statistical analysis, it was concluded that the effluent color was not affected by the influent color and MLSS concentration (for DEC and PAC). However, it was mainly affected by the influent color for bentonite, activated clay and Macrosorb. When DEC and PAC are compared economically, it can be seen that they almost have the same unit prices. The low sludge production is the most important advantage of DEC addition.

In this study, the optimum sludge and hydraulic retention times for removal COD and color in cotton textile industry wastewaters were found to be 30 and 1.6 days. The kinetic constant were determined as Y=0.76 kg MLSS/kg COD, Kd=0.026 1/day, Ks=113.3 mg/L, k=0.423 1/day and μmax=0.32 kg MLSS/kg COD day.