Hazardous waste landfill leachate treatment by combined chemical and biological techniques

The efficacies of coagulation, ozonation, Fenton treatment, activated sludge process, Fenton treatment-activated sludge process (CHEM-BIO) and activated sludge process-Fenton treatment (BIO-CHEM) to treat hazardous waste landfill leachate were investigated and compared. The results of the biodegradability test revealed a high content of readily biodegradable organic matter in semicoke landfill leachate, and thus, aerobic biological oxidation was found to be a more reasonable and cost-effective technique for leachate treatment than direct chemical processes (ozonation, Fenton treatment). However, in terms of treatment efficacy, both chemical and biological processes resulted in a high residual organic load, indicating an insufficient leachate quality improvement. The treatment performance of the combined schemes (BIO-CHEM and CHEM-BIO) proved more effective and ensured the removal efficacy percentage met that required by EU legislation as well as the specific target discharge limits of the measured parameters. Accounting for the treatment cost-effectiveness, BIO-CHEM proved to be a more feasible option and could be suggested as the most efficient and practicable technological scheme for hazardous waste landfill leachate treatment.