Effects of Sewage Sludge Application in Agriculture on Soil Environment

Land application of sewage sludge is one of the effective disposal alternatives.In this paper,the effects of agricultural application of domestic sewage sludge on soil environment were discussed from the respects of physicochemical properties,heavy metals pollution and organic pollution.Sewage sludge application provides nutrients to improve the soil structure and enhance the soil fertility.There was no significant correlation between the length of application lasting time and the heavy metals concentration in soil,which meant the main factors resulting in increasing heavy metals contents in soil were the quantity of sewage sludge application and the contents of heavy metals in sewage sludge.Normal application of sludge containing organic pollutants in normal contents would not produce organic pollution of groundwater.But there was a danger that some organic pollutants transfer into the food-chain by accumulation of plants and/or animals,which depended on the contents of organic pollutants in sewage sludge and the quantity of sewage sludge application.Pretreatment of sewage sludge before land application to degrade organic pollutants is necessary to improve the safety of sewage sludge land applications.