Ozonation of refractory chemicals in leachate with hydrogen peroxide

Article type: Research Article

Authors: Peng, Wang | Lau, W C Ivan | Fang, H P Herbert

Affiliations: Department of Environmental Science and Engineering, Harbin150001, China, E-mail: pwang73@yahoo.com | Department of Civil Engineering, The University of Hong Kong , Hong Kong SAR, China

Abstract: Nearly 97% of organic chemicals in Hong Kong leachate could be effectively removed by the UASB(upflow anaerobic sludge blanket) process followed by the Fenton coagulation. The COD of leachate was lowered from an average of 12900 mg/L to 1440 mg/L after the UASB treatment, and was further lowered to 394 mg/L after the Fenton coagulation. The remaining refractory residues could be further removed by ozonation with the addition of H_2O_2. The ozonation for the supernatant of the Fenton coagulation was mosteffective at pH 7-8, with the addition of 300 mg/L of H_2O_2, and 30 min of reaction. The final effluent contained only 85 mg/L of COD and 10 mg/L of BOD_5. On the other hand, direct ozonation of UASB effluent lowered the COD to 905 mg/L and BOD_5 to 103 mg/L.Ozonation improved the biodegradability of the organic residues,and also converted part of organic-N in the leachate into NH_3-N and NO_3^--N.

Keywords: biodegradability, Fenton coagulation, hydrogen-peroxide, leachate, ozonation, UASB

Journal: Journal of Environmental Sciences, vol. 14, no. 4, pp. 495-500, 2002