The purpose of this paper is to elaborate a plan for the leachate treatment at the “Zeljkovac” sanitary landfill in Leskovac city. Different processes occur over time  at the landfill. The processes of infiltration and transpiration occur continuously, distributing the humidity and affecting the water balance within the body of the landfill. The landfill body acts as a giant sponge, in which water moves, and from which water can be released - both into groundwater and into the atmosphere in the form of water vapour or as a filtrate at the bottom of the landfill. In this paper, particular attention is given to the kind of waterwhich is actually filtrate from a landfill, often called leachate. The efficiency of the most commonly used methods will be presented, depending on the most prevalent pollutants  in leachate. As there are many methods for treating this kind of wastewater, the reverse osmosis method will be presented as one of the most widely used . The technological process of a reverse osmosis plant will be described, as well as the result that shows the output quality of the leachate after the treatment process. The major finding of this paper reflects a clear justification for using this method to achieve the desired efficiency of leachate treatment.

The paper presents the procedure of examination and characterization of sludge from wastewatertreatment. This procedure includes: sampling, identification with categorization of waste, characterization dependingon the degree of danger, characterization of the subject waste as hazardous waste and determination of theconcentration of hazardous substances, determination of physico-chemical and toxicological characteristics andeffects on human health, determination of the impact on the environment and others procedures in accordance withthe applied methodology and preparation of reports on waste testing. The testing and characterization process beginswith sampling and ends with reporting. The goal of wastewater treatment is to obtain clean water, while sludge isproduced as a by-product. Clean water returns to nature, and sludge goes to treatment and final disposal. Thetreatment can be: sanitary disposal, recycling using composting technology with the aim of obtaining compost orenergy utilization as solid fuel or using anaerobic digestion with the aim of obtaining biogas.

In addition to material recycling, municipal solid waste (MSW) can be treated with so-called, energy recycling or thermal treatment. The basic conditions that need to be met for this are that MSW can justifiably not be treated with priority material recycling and should have a certain acceptable energy potential for thermal treatment. The paper presents the morphological composition of MSW, generated amount on the territory of the City of Leskovac for 2020, with emphasis on the calculation of the energy potential of MSW, on the basis of which a decision should be made whether material or energy recycling (thermal treatment) will be applied.