As reported in recent literature, ultrafiltration is introduced into the technological cycle for total neutralization of landfill leachate. The ultrafiltration may be treated as a filter before the reverse osmosis stage, both in the system of biological treatment [90,93] and in two-stage reverse osmosis . Figure 23 presents the solution concept  of the affiliated method consisting of the following stages:
• biological pretreatment and ultrafiltration;
• reverse osmosis method;
• evaporation of retentate.
In the course of biological treatment, some of the organic compounds undergo biodegradation, whereas the remaining ones, together with nitrogen compounds, are removed in effect by flocculation. The first stage of the process is carried out in the denitrification reactor, in the reactor with activated sludge, and in the ultrafiltration system. The purpose of the ultrafiltration process is to remove the activated sludge from the effluent. It also replaces a drumtype filter, biological reactor and settling tank used in the conventional system for the treatment of effluents by means of the affiliated biological method and reverse osmosis. Organic refractive compounds and inorganic compounds left after the first stage are removed using reverse osmosis. The volumetric permeate capacity in the reverse osmosis is 75-80%, and the permeate may be discharged to surface waters. The retentate undergoes recirculation to the dump or is further utilized using evaporation and drying.
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