Determination of inert COD from different dyestuff used textile industries

This study was performed to compare the chemical oxygen demand (COD) fractions of textile wastewaters containing reactive and indigo dyestuffs. In the textile wastewater containing reactive dyestuff, inert soluble COD (SI) concentration was found as 94 mg/L and residual soluble microbial products concentration (SP1) was 53 mg/L. This total (SI + SP1) was about 21 ratios of total initial COD (CTO). On the other hand, in the textile wastewater containing indigo dyestuff, SI and SP2 were observed as 160 mg/L and 69 mg/L, respectively, which is about 21 ratios of CTO. The investigation of different dyestuff used wastewaters indicated that indigo dyestuff used textile industry wastewater had higher inert COD content due to the complex structure of the indigo dyestuff. However, the biodegradability characteristics show similarity for both wastewaters. The results also indicated that biological treatment alone cannot be adequate to provide the discharge limits for both wastewaters. (C) 2011 American Institute of Chemical Engineers Environ Prog, 201