To begin with, let’s start with what landfill leachate is? It is a complex liquid consisting of high levels of biodegradable as well as non-biodegradable substances, including phosphate, organic matter, sulfide, phenols, heavy metals, and ammoniacal nitrogen. Leachate is the result of water in a waste landfill (such as power plant coal combustion residuals) that percolates through the landfill. Leachate treatment must be handled as wastewater that, if not done properly and timely, could result in severe ground and surface water contamination. Several treatment methods have been developed specific to the landfill characteristics to make certain that the risks of leaving untreated leachate are effectively alleviated. However, all these techniques are not very user friendly. Some are quite expensive, complicated, require monitoring and need adaptation to local conditions from start to finish.
In choosing the right leachate treatment system, we should be mindful that ineffective leachate management has the potential to put an operation into regulatory violation resulting in financial sanctions and operation disruptions. We therefore must consider all the substances present in its composition, landfill conditions, characteristics of entering water, concentration and toxicity of contaminants. The wastewater technology that is employed to deal with the situation must serve the objective of an effective leachate collection and removal system (LCRS).
Municipal solid waste leachate contains a high degree of dissolved solids from a wide variety of sources, depending on the composition of the waste material. Leachate from coal combustion residuals (CCR) has a high proportion of fines—dust-sized particles, particularly from fly ash. These particles have the potential to clog LCRS and sump pumps and can cause abrasion that increases maintenance costs as well as limiting the service life of the pump.
For this reason, filtration systems are important in CCR landfills, to keep the fines from entering the LCRS and then the pump.