BIOLOGICAL TREATMENT OF DYE WASTEWATERS USING AN ANAEROBIC-OXIC SYSTEM

Three dye solutions, namely, C.I. Acid Yellow 17, C.I. Basic Blue 3, a nd C.I. Basic Red 2, were treated in an upflow anaerobic sludge blanke t (UASB) reactor followed by a semi-continuous aerobic activated sludg e tank When hydraulic retention time was about 12 hours, no significan t color removal was observed in the aerobic stage. In the anaerobic st age, Acid Yellow 17, Basic Blue 3, and Basic Red 2 were removed by 20% , 72%, and 78%, respectively. To treat wastewater from a dye manufactu ring factory with COD concentration of 1200 mg/l and Color of 500 degr ee (dilution factor), an UASB reactor (4.5 liters) and an activated sl udge tank (5 liters, adjustable), COD and color were removed by more t han 83% and 90% at a COD loading rate of 5.3 kg COD/m(3)-day in the an aerobic stage, and at the hydraulic retention time of 6-10 hours for t he anaerobic stage and 6.5 for the aerobic stage. The anaerobic stage of the A/O system removes both color and GOD. In addition, it also imp roves biodegradability of dyes for further aerobic treatment. Copyrigh t (C) 1996 Elsevier Science Ltd