Effect of different methods of treatment of municipal sewage sludge on their physicochemical properties and their agricultural utilization

In the study the physicochemical properties of selected municipal sewage sludge were compared using the reports on waste generation from the years 2007–2012 in the Mazovia voivodship. The selection was done on the basis of different methods of sludge processing and the number of equivalent inhabitants (NEJ) supported by sewage. Physical and chemical properties of municipal sewage sludge were significantly dependent on the method of purification and treatment methods. These sludges were characterized by a high content of organic matter and macronutrients. The amount of heavy metals (Pb, Cd, Cr, Cu, Ni, Hg and Zn) were within acceptable standards for municipal sewage sludge used in agriculture. Municipal sewage sludge treated by biological method with higher nutrients removal did not create bacteriological danger and were used in agriculture, generally to the cultivation of all agricultural products. Sewage sludge sanitized with lime and subjected to anaerobic digestion did not meet bacteriological standards, which eliminated their use in agriculture.