Step-Feed Technology in SBR to Enhance the Treatment of Landfill Leachate

Municipal solid waste leachate is the liquid leached from a landfill. The annual production of municipal solid wastes in Sri Lanka, is mostly disposed via landfilling or open dumping. The generation of leachate is caused principally by precipitation, percolating through waste deposited in a landfill. Once in contact with decomposing solid waste, the percolating water becomes contaminated and if it then flows out of the waste material, it is termed leachate. This leachate (if not collected and treated) poses dangerous environmental and health risks due to its impact on surface and ground waters. Leachate may contain large amounts of organic matter (biodegradable, but also refractory to biodegradation), where humic-type constituents consist as the important group, as well as ammonia-nitrogen, heavy metals, chlorinated organic and inorganic salts (Renou et al. 2008). It is very costly to clean up when they contaminate the groundwater. Figure 7.1 shows a typical municipal landfill.