The treatment of landfill leachate presents a complex environmental challenge, given the variable and highly polluting nature of these liquids. Leachate is produced when rainwater seeps through waste and contains high concentrations of organic pollutants, ammonia, heavy metals and dissolved salts. To tackle this issue effectively, advanced technologies and integrated approaches are employed.

One of the most effective techniques for treating leachate is the use of flat-sheet reverse osmosis membranes. This process enables the selective separation of contaminants, producing a clean permeate and a concentrate for further treatment. Flat-sheet reverse osmosis membranes ensure high removal efficiency, particularly for salts and micropollutants.
However, to optimise the process and extend the service life of the membranes, physico-chemical pre-treatment is often necessary. This may include pH adjustment, flocculation, heavy metal precipitation and filtration, thereby reducing the pollutant load and preventing membrane scaling or fouling.

A particularly critical issue is the high content of ammoniacal nitrogen in leachate. To remove it effectively, stripping towers are used, which separate the ammonia through a desorption process using air or steam. The stripped ammonia can then be absorbed into acidic solutions, such as sulphuric acid, to produce ammonium sulphate, a commercial fertiliser.

This approach not only reduces the environmental impact of leachate, but also enables the recovery of certain by-products. In particular, the ammonium sulphate obtained can be reused in agriculture, thereby closing the nutrient cycle. The integration of advanced separation technologies with resource recovery now represents a sustainable and circular strategy for the management of waste and landfill leachate.