What is landfill leachate?

Landfill leachate is caused in particular by the infiltration of rainwater or surface water, by the inherent moisture of the stored waste or by the infiltration of groundwater due to inadequate sealing of the landfill. If untreated leachate enters water bodies such as rivers, lakes or seas, this poses a considerable threat to the environment.

What should be considered with landfill leachates?

Landfills usually have an extremely inhomogeneous mixture of substances, which can contain both organic and soluble mineral substances. In addition to the type of waste stored, the composition of the leachate is also determined by the weather conditions and the length of time the landfill has been in operation. A long standing time leads to a large number of water-soluble nitrogen and sulphur compounds, chlorides, sulphates and a high proportion of organic substances that are difficult to biodegrade in the leachate. In some cases, after treatment of the organic substances and nitrogen, the leachate can be discharged to the nearest wastewater treatment plant for further treatment. Sometimes, however, it is necessary to purify the leachate to an effluent quality that meets the limits for direct discharge. The C-deg team is available to advise you on all aspects of leachate treatment at your landfill.

Treatment by reverse osmosis

C-deg uses the reverse osmosis process to reliably purify landfill leachate.

The conventional osmosis process is based on the diffusion of water or another solvent from the side of a lower concentration through a membrane to the side of a higher concentration. This allows the concentration gradient to be balanced, resulting in the so-called osmotic pressure.

If a pressure is subsequently applied which is higher than the osmotic pressure of the solution, a reversal effect results and the solution is pressed through the membrane in the direction of the lower concentration. This separating process allows dissolved solids, molecules and ions to be filtered out of the contaminated leachate. Thus, two phases are created: the thickened concentrate with almost all pollutants from the leachate and the permeate. The permeate is almost pure water that has a direct discharge quality according to the Waste Water Ordinance (AbwV, Annex 51). The ratio of permeate to concentrate is approx. 70 : 30 %. The remaining concentrate can either be returned to the landfill or passed on to authorised specialists for treatment – much more cost-effectively due to the reduced volume.

Reverse osmosis systems from C-deg

The osmotic pressure of a solution depends on the concentration and type of dissolved substances. For this reason, C-deg reverse osmosis systems operate in different pressure ranges depending on the application. For the purification of landfill leachate, up to 60 bar or more are required. Our plants are in operation 365 days a year and 24 hours a day, there is hardly any downtime. Our on-call service provides support, and the plastic membranes are cleaned and replaced regularly.