The Environmental Impact of Biosolids’ Land Application

Abstract

Increasing urbanization and industrialization have resulted in a dramatic increase in the volume of wastes generated worldwide. The treatment of wastewater results in large amounts of municipal treated sewage sludge, or biosolids. Sludge has traditionally been disposed through ocean-dumping, landfilling, or incineration. But due to increasingly stringent environmental regulations, these disposal methods are being phased out. With increasing populations worldwide, biosolids production is likely to continue to increase in a near future. The safe disposal of biosolids is a major environmental challenge. Land application of biosolids is largely considered the best option of disposal because it offers the possibility of recycling plant nutrients, provides organic material, improves soil?s chemical and physical properties and enhances crop yields. The use of biosolids is increasingly being considered as a feasible and technical solution to reverse degraded and less productive lands, and to promote the reestablishment of a vegetative cover. However, benefits have to be carefully weighed against potential deleterious effects related to non-point source pollution, that include increased potentially trace elements (PTE) input, leaching of nitrogen (N) in subsurface drainage and groundwater, contamination of surface water with soluble and particulate phosphorus (P), vector attraction, and reduced air quality by emission of volatile organic compounds, among others. Most countries regulate concentrations of PTE and pathogens in biosolids and mandate maximum permissible loading rates into soil to manage contaminants. Nevertheless, concerns associated with adverse environmental effects due to land application of biosolids continue. This chapter investigates the environmental impact of biosolids land application related to soil properties.