RESUMO
The secondary effluent of three WWTPs was treated by ozonation to investigate organic biodegradability enhancement. The bulk experimental method was used. Ozone adding dosage was controlled to be 2, 4, 6, 8, 10 mg/L by adjusting the adding time. Results showed, UV254 and SUVA(UV254/DOC)decreased with the increasing of the ozone dosage. When ozone adding dosage was 6 mg/L, UV254 and SUVA decreased about 54.4% and 56.6% respectively; while BOD5/COD, BDOC and BDOC/DOC were improved above 30%, 360% and 360% respectively. It could be concluded that suitable ozonation could improve the biodegradation of the organic substances in the secondary effluent. The organic substance was analyzed by the excitation-emission matrix (EEM) to investigate the variation regularity of organic matter changes of the ozoned and non-ozoned secondary effluent. The main organic substances of the secondary effluent in the plant were aromatic protein like substances and humic substances, ozone could significantly remove these types of organic substance.