Treatment of Leachate from sanitary landfills has been found to be a much different and more complex problem than the treatment of municipal wastewater. Greater variability in the characteristics and quantities, of the waste, isolation of the landfill site and the need for simple treatment methods are three reasons why leachate treatment needs special consideration. Typical characteristics of this waste are high strength, a low BOD/COD ratio, limited phosphorus and excessive ammonia nitrogen, along with various toxic contaminants.
A number of aerobic and anaerobic methods used to treat leachate are described in this paper and the advantages and shortcomings of each are noted. Supplementary processes including nitrification, nitrogen removal, recirculation and land spraying are also discussed. From experience with these earlier systems it appears that, in the future, more consideration should be given to: equalization of leachate flow, anaerobic rather than aerobic processes, nitrification of the leachate and utilization of landfill gas. Land spraying and recirculation of leachate also warrant wider application.