PROPERTIES OF SEWAGE SLUDGE RESULTED FROM URBAN WASTEWATER TREATMENT IN THE REPUBLIC OF MOLDOVA

Sewage sludge represents the solid sediments accumulated at the urban wastewater sewage treatment plants through the sewage system. It consists of clay particles, organic substances contained in sewage water, human defections, mineral salts with macro and microelements, heavy metals, pathogenic agents. The quantity of sewage sludge annually produced in the Republic of Moldova is of about 36,000 tons dry mass and of about 2,000 tons with the humidity of 50%. The organic waste materials which originate from urban activity are more known as a source of environment pollution and less as a source of nutritive elements having benefic effects on soil and vegetation. They are varied and have a very complex composition depending on the sector and the activities they originate from. Among the most difficult issues related to the waste materials are their storage, recycling, and usage. A possible solution in order to eliminate them from the given zones and use them purposefully is to introduce them as a component part in the technological systems of soil cultivation in various aspects of agriculture in the conditions of environment protection and maintaining some reasonable prices. The application of sewage sludge on agricultural lands for their reintegration in the matter circuit is a very feasible one [1-3].