Contemporary practices and findings essential to the development of effective MSWI ash reuse policy in the United States

Municipal solid waste incineration (MSWI) in the United States generates a significant amount (∼6.6 million mtons) of ash annually, yet the utilization of this ash in beneficial use applications is nearly non-existent. In some European and Asian nations, policy regulates the use of MSWI bottom ash in construction with an accepted degree of environmental and human health risk. Both federal and state-level solid waste policy in the United States largely does not address ash reuse. U.S. MSWI industry practices have been adapted to avoid hazardous waste generation and primarily practice ash disposal in monofills. Numerous case studies and laboratory experiments have characterized MSWI ashes with regard to the potential environmental contaminants and have demonstrated the efficacy of bottom ash in specific reuse scenarios. In reviewing these studies, and by analyzing the reuse policy in several nations, the authors identify key aspects of effective MSWI ash reuse. These are discussed within the framework of available data and information, and examples are provided. Moving toward the sustainable management of resources such as MSWI bottom ash will require U.S. state-level policy to address the conditions under which ashes may or may not be reused. Suggestions on practices (often already occurring in many other areas of the world) to facilitate the reuse of MSWI ashes are provided.