Landfill Leachate Treatment
In recent years the number of municipal landfills has grown considerably. This is a very welcome development, as one of its aims is to reduce illegal waste dumping and the pollution and health damage it causes. With a delay of a few decades, related developments followed at the landfills: the use of landfill gas as a new source of energy and, as a new environmental requirement, the treatment of leachate.
Rainwater passes through the large, open surface of a landfill practically unhindered (depending on the weather, some of it may evaporate), dissolving a wide range of water-soluble substances on the way. Which substances these are depends simply on what waste has been delivered. Industrial production is not the only source: household waste can also contain chemicals, drug residues, detergents and the like, which may dissolve in the rainwater. Landfills are built with multilayer impermeable liners which, in principle, prevent contamination of the soil and groundwater. However, under extreme conditions (such as the weather) the volume of liquid collecting in the landfill can grow to the point where it hinders normal operation, and it then has to be removed. This liquid can carry extremely high levels of dissolved organic matter, dissolved salts and even metal salts, so its disposal is severely restricted. The degree of contamination depends on the quality of the materials permitted and actually deposited, the landfilling technology, the age of the landfill and many other factors.
The leachate treatment technology depends on the required final quality. The treated water may be discharged to the public sewer or to a natural watercourse, and part of it can be recirculated to keep the landfill moist. These factors, together with other environmental and economic considerations, determine the solution to be built.
Several sub-processes of leachate treatment are the same as those used in industrial wastewater treatment (coagulation-flocculation, phase separation, sludge dewatering, etc.). This lets us put the experience we have gained in that field to good use in landfill leachate treatment in Hungary.
Process flow diagram
The flow diagram shows one possible alternative. Depending on the specific local circumstances, conditions and technical parameters, the actual treatment technology may differ from it.
Main steps of the alternative shown
- collection and pumping of the leachate
- pH adjustment and coagulation by dosing ferric chloride or PAC in a two-stage reactor
- flocculation with polymer solution, phase separation by sedimentation
- sludge collection and dewatering
- sand filtration
- ammonia removal by stripping, biofilter and chlorination
- activated carbon filtration (dechlorination)
- polishing by reverse osmosis (RO) and discharge of the treated water
KÖRTE Környezettechnika Kft., a specialist in industrial wastewater treatment in Hungary, offers its clients a complete, turnkey solution. If you would like to discuss leachate treatment at your landfill, please contact us through one of our available channels.