Color removal of Remazol[R] dyebaths wastewater by UV/H sub(2)O sub(2) 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/H sub(2)O sub(2) process, mainly to remove color due to reactive Remazol dyes (Chemical Oxygen Demand [COD] 600 mg O sub(2) L super(-1); Biochemical Oxygen Demand [BOD] 220 mg O sub(2) L super(-1); Total Organic Carbon (TOC) 310 mg C L super(-1)). Experimental designs were performed to assess the effects of variables (initial pH, temperature, and initial [H sub(2)O sub(2)] and optimize treatment conditions. Those were: initial pH = 11, temperature (T) = 50 degree C, and initial [H sub(2)O sub(2)] = 3.1 x 10 super(-4) mol L super(-1). The response variables were color removal and residual [H sub(2)O sub(2)]. After two hours of irradiation, color removals of approximately 80 and 75% for UV/H sub(2)O sub(2) 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.