Use of sequencing batch reactors and Fenton's reagent to treat a wastewater from a textile industry

This study investigated the potential of biological treatment as a single process as well as in association with chemical oxidation to treat a textile wastewater. The experimental part incorporated the following three schemes: biological treatment only (stage 1), chemical oxidation prior to biological treatment (stage 2), and biological treatment followed by chemical oxidation (stage 3). Biodegradation was accomplished employing three identical sequencing batch reactors (SBRs), each having a liquid volume of 10L, while chemical treatment involved the addition of Fenton's reagent in the range 25-300 mg/L, in a batch-type operation. Following an acclimation period of approximately 60 days, biological treatment resulted in a high percent reduction in chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), and total phosphorus (TP), and in a moderate decrease in color. The process was found to be independent of the variations in the anoxic time period studied; however, an increase in solids retention time (SRT) improved COD and color removal, although it reduced the nutrient (TKN and TP) removal efficiency. Furthermore, both combined treatment alternatives resulted in enhanced color reduction, in comparison to stage 1. Overall, chemical oxidation prior to biological treatment (stage 2) appears to be the best option regarding the treatment of the textile wastewater used. (C) 2004 Elsevier B.V. All rights reserved.