%0 Journal Article
%T Land Application of Biosolids in the USA: A Review
%A Qin Lu
%A Zhenli L. He
%A Peter J. Stoffella
%J Applied and Environmental Soil Science
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/201462
%X Land application of biosolids has proven a cost-effective method of waste disposal by beneficially recycling organic matter and nutrients and improving soil quality; however, it may also pose potential threat to the environment and human health. The purpose of this paper is to provide information on recent research progresses and regulation efforts regarding land application of biosolids, including forms and types and nutrient values of biosolids, environmental and health concerns, and related best management practices (BMPs) of biosolids application, with emphasis on its land application in agriculture. More research and regulations are expected to minimize potential risks of biosolids land application, especially its long-term impacts. 1. What Are Biosolids? Fifty years ago, partially treated wastewaters from thousands of US cities were discharged into the nation¡¯s rivers, lakes, and bays. These receiving water bodies became heavily polluted [1]. Since 1950s, federal legislation has been strengthened to control water pollution. Municipal sewage treatment systems or publicly owned treatment works (POTWs) were built, although ocean disposal of residual solids was still permitted. The Federal Water Pollution Control Act Amendments of 1972 (PL 92-500, 1972) placed further restrictions on the discharge of wastewater to waterways and encouraged other disposal methods such as land applications. Recent restrictions on ocean disposal (Ocean Dumping Ban Act, 1988) and cost increase of incineration and landfill make land application an attractive option of disposal. Wastewater usually undergoes two processes in treatment factories. The primary step is a physical screening or settling process to remove sediment but with all the dissolved minerals still in the effluent. The secondary step is a biological process where dissolved biological matter is progressively converted into a solid mass using a cultivated culture of indigenous, water-borne bacteria, thereby large amount of biological oxygen demand (BOD) is removed from the wastewater. A tertiary step, which is a chemical and/or biological process, may also be employed to remove nutrients especially N and P, which are the main concern of eutrophication of waters [2]. After the tertiary step, the effluent may be suitable for discharge into a stream, river, lagoon, or wetland or used for irrigation of public area such as golf courses, greenways, or park or injection to groundwater. To meet the regulatory requirements (40 CFR Part 503, described below) for land application, the wastewater treatment residuals
%U http://www.hindawi.com/journals/aess/2012/201462/