Specification of sewage sludge arising from a domestic wastewater treatment plant for agricultural uses

The application of sewage sludge for fertilization purposes and soil amendment is arousing great interest within the scientific community in the last few years especially as the consumption of commercial fertilizers is continuously increasing and most farmers could not bear the additional cost in the rise in fertilizer prices. The objective of this research is to study the specification of sewage sludge from drying beds of Jijel wastewater treatment plant, dewatered by natural evaporation in order to assess its potential for agricultural reuse as a soil amendment. It is a sludge resulting from the secondary treatment of domestic sewage by activated sludge processes (biological treatment). A good characterization of sewage sludge goes through several steps to assess its quality and its compliance with the established requirements and guidelines for agricultural valorization in Algeria. Physicochemical analysis showed that the sewage sludge contains significant quantities of major nutrients (N, P, K) and moderate amounts of secondary nutrients (Ca, Mg, S), It is generally rich in organic matter with an average of 41.2%. The most harmful heavy metals (Cu, Cr, Ni, Pb, Cd, Se, and Hg) found are present in small amounts and still below accepted standards. Some beneficial microelements for plant growth such as Fe, Co, and Mn are detected in varying quantities. For bacteriological characteristics, both of total and fecal coliforms are identified in sewage sludge with 8.1 × 103 and 1.1 × 103 cfu/g, respectively, but we have noticed an absence of Salmonella