Landfill leachate is defined as all water that has been in contact with waste stored in a landfill. It arises primarily as rainwater seeps through the landfill body, but also from the moisture inherent to the waste itself or – in the case of inadequately sealed landfills – groundwater ingression.
The leachate usually contains high concentrations of ammonium, organic matter, toxic compounds and heavy metals. Some of the organic substances decompose naturally in the landfill body
Due to these exothermal processes inside the landfill, the temperature of the leachate is usually higher than typical groundwater in the area. Landfill leachate is usually quite turbid, has a very strong odor and a brownish color.
The composition of landfill leachates differs depending on the type of waste stored, the weather and the holding time in the landfill body. As the landfill holding time increases, so too does the degree of persistent organic pollutants.
After two to five years, the initially aerobic decomposition processes give way to anaerobic processes. Initially, anaerobic decomposition consumes only short-chain fatty acids, and the organic compounds entering the leachate are still reasonably biodegradable. As the landfill holding time increases, anaerobic decomposition progresses to methane production. In addition to a range of soluble nitrogen and Sulphur compounds, sulphates and chlorides, the leachate then contains a high degree of persistent organic pollutants
The formation of leachate threatens the groundwater, soil and environment. For this reason, treatment methods to remove ammonium need to be explored. To treat landfill leachate, an option is to send leachate to a wastewater treatment plant nearby. However, often environmental regulations require leachate to be treated on-site instead of being treated in the municipal wastewater treatment plants.
Considering the high organic content of landfill leachates biological treatment processes are ideally suited. Given the limitations of suspended growth activated sludge systems such as inadequate sludge settle ability and excess sludge production, it is advantageous to use more advanced processes. The solution for many facilities requiring advanced biological treatment, is Moving Bed Biofilm Reactor technology. Using Headworks BIO biofilm carrier technology, MBBR establishes a high-density population of bacteria within a compact biological wastewater treatment process, reliably biodegrading target organics in the wastewater stream for economic reduction prior to compliant discharge. The major advantage of the MBBR is a self-sustaining biological process, eliminating the need to periodically waste sludge and the requirement to supply a dilute return activated sludge. As a result, there is no requirement to supply a return sludge line. Further the operation is simplified due to the self-regulating nature of a fixed film system, substantially reducing the complexity of operator intervention.
Leachate Treatment Plant
