Sewage Sludge

Abstract

Sewage sludge (SS), also termed “biosolids”, is a derivative of handling processes carried out for sewage sludge. Sewage sludge is a basin of organic material and nutrients, so it encompasses a possible substrate for selection of probable circumstances. Much water, a high amount of organic matter and the presence of high amounts of pathogenic microorganisms in solids are removed during preliminary sedimentation. The disposal of sewage sludge to agricultural soil is one of the best disposal alternatives. The quality of sewage and nature of processes used for the treatment show the characteristics of sewage sludge. Because there is a presence of various “organic and inorganic plant nutrients” in sewage sludge it may be a best alternative for fertilizer, but due to the presence of various toxic elements its use is often restricted. Amendment of sewage sludge to soil mutates its physico-chemical properties and soil microbial properties. Crop yields in soil amended with sewage sludge are usually higher than that of well-fertilized controls. Metals bioavailability elevates in sewage sludge amended soil at extreme amounts of application for many years. There is a difference in the quality of the primary sludge and secondary sludge as well. Methods of stabilization of sludge treatment and disposal methods are dependent upon its composition. The composition of sewage sludge is highly uneven and it depends upon many aspects such as seasons, the technology behind different wastewater treatment plants and the specificity of pollutant source areas, etc. The aim of this chapter is to review the accessible information on the application of sewage sludge on the fertility of soil and resulting effects on the production of plants.