Land Application of Wastewater Sludge

Book excerpt: Prepared by the Task Committee on Land Application of Sludge of the Committee on Water Pollution Management of the Environmental Engineering Division of ASCE. This report presents research on the land application of wastewater sludge, especially quantitative and qualitative aspects of soil-sludge interaction. Each year, approximately 6.2 million dry metric tons of wastewater sludge are produced by municipal wastewater treatment facilities in the United States. The annual sludge production is expected to reach 12 million dry metric tons by the year 2000. Sludge use and disposal options include incineration, ocean disposal, marketing of processed sludge, landfilling, and land application. Land application of sludge is achieved by spreading the sludge over the ground surface or incorporating it within the topsoil by injection, disking, or plowing. Sludge is applied to agricultural and forest lands for its nutrient value and to disturbed areas for soil amendment and reclamation purposes. At present, land application is the logical alternative because of its environmental and economic advantages over the other methods. Topics include: mechanisms for the removal of nitrogen and phosphorus, the role of trace elements, hydrologic effects of soil-sludge interaction, use of municipal sludge to reclaim mined land, and health effects. The report concludes with recommendations for future research.