Aerobic Bio-Treatment of a High-Strength Leachate

The potential adverse environmental effects of landfill leachates have been well documented and their control and treatment is currently the subject of considerable research. This study investigated aerobic biological treatment of a high-strength leachate, without any prior removal of heavy metals or toxic substances. Using high MLVSS concentrations (8000 ppm-16,000 ppm), along with the combination of air and mechanical mixing, to control foaming, digester stability was achieved with sludge ages ranging from 10 days-60 days. With influent COD concentrations between 44,000 ppm and 52,000 ppm, settled effluent COD removal efficiencies greater than 97% were obtained. Increasing the sludge age from 10 days to 20 days, significantly improved the quality of the settled effluent. In addition, the leachate contained such heavy metals as aluminum, cadmium, chromium, copper, lead, nickel, and zinc. Zinc exhibited the highest influent concentration at greater than 200 ppm.