Advanced treatment of dyehouse effluents by Fe(II) and Mn(II)-catalyzed ozonation and the H2O2/O3 process

Treatment of synthetic dyehouse effluent containing six reactive dyestuffs and their assisting chemicals by O-3/Fe(II), O-3/Mn(II), and O-3/H2O2 advanced oxidation processes was investigated. All oxidation processes were capable of completely decolourizing the wastewater within 30 min. Decolourization proceeded fastest by the O-3/Mn(II) process, whereas the O-3/H2O2 combination was more efficient in the removal of DOC (Dissolved Organic carbon) and UV254nm which were 11 and 53%, respectively, for one hour treatment time. Application of Fe(II)-catalyzed ozonation provided an effective means of removing colour and COD (Chemical Oxygen Demand) by a five- and nine-fold enhancement, respectively, compared with conventional coagulation applied at the same coagulant doses. Formation of toxic oxidation products was not observed during the course of treatment with all investigated advanced oxidation processes.