Color removal of Remazol ® dyebaths wastewater by UV/H2O2 does not decrease TOC, BOD/COD, and toxicity of the effluent

The present paper aimed at treating the dyebath wastewater of a textile industry by the UV/H2O2 process, mainly to remove color due to reactive Remazol((R)) dyes (Chemical Oxygen Demand [COD]600mg O-2 L-1; Biochemical Oxygen Demand [BOD]220mg O-2 L-1; Total Organic Carbon (TOC)310mg C L-1). Experimental designs were performed to assess the effects of variables (initial pH, temperature, and initial [H2O2]) and optimize treatment conditions. Those were: initial pH=11, temperature (T)=50 degrees C, and initial [H2O2]=3.1x10(-4) mol L-1. The response variables were color removal and residual [H2O2]. After two hours of irradiation, color removals of approximately 80 and 75% for UV/H2O2 and direct photolysis were respectively achieved. BOD/COD ratios, TOC, and COD analyses showed no significant changes. Acute ecotoxicity tests, using lettuce (Lactuca sativa) seeds, showed a slight increase in the ecotoxicity of the treated wastewater, for both processes. So, they are not recommended for treating this kind of wastewater.