Effect of Ozonation on Degradation of Organochlorine Compounds in Biosludge of Pulp and Paper Industry

The waste-activated sludge in the pulp and paper industry has been classified as hazardous waste due to the presence of organochlorine compounds. The fate of organochlorine compounds during ozonation of biosludge as well as subsequent treatment in activated sludge process has been studied. Ozonation of biosludge at 45.3 ± 2.1 mg O₃/g dry solid dosage resulted in 23 ± 2 and 26 ± 4% removal of adsorbable organic halides and extractable organic halides compounds, respectively. Out of 12 chlorophenolic compounds identified by USEPA for regulation, 10 compounds were detected in the biosludge and 19–68% removal of the individual compounds was observed during ozonation. High molecular weight chlorinated compounds were decomposed to low molecular weight ones with partial dechlorination. The ozonation followed by biological treatment can remove more than 80% of organochlorine compounds.