Studies in treatment of disperse dye waste: membrane–wet oxidation process

An integrated process, membrane–wet oxidation (MEMWO) has been demonstrated to treat the disperse dye bath waste. The dye bath waste stream containing azo class disperse dye CI 79, was studied to demonstrate the process. A nanofiltration membrane (MPT 30) showed >99% color and 97% chemical oxygen demand (COD) rejection of dye compound. The concentrate was then treated by wet oxidation (WO) process. WO of dye was studied in the range of 160–225°C and oxygen partial pressure 0.69–1.38 MPa. A homogeneous copper sulfate was found to be a suitable catalyst to effectively destroy the dye as well as the real waste. While non catalytic WO of dye achieved 75% reduction in COD during 120 min with 99% color destruction, the catalytic WO showed about 90% reduction in COD. The performance of WO of actual waste stream was comparable with that of pure dye molecule.