Opportunities and challenges with implementing a recycling program for municipal solid waste incineration (MSWI) bottom ash as a construction aggregate: A programmatic review.

The incineration of municipal solid waste (MSW) produces byproducts known as MSW incineration (MSWI) ash. The reuse of MSWI ash as a construction material prevails in several areas of the world, namely Europe and Asia, however, reuse in the United States (US) lags due to regulatory requirements for disposal practices. Developing a recycling program for MSWI ash provides an alternative end-of-life disposal scenario for material currently landfilled and supplements the reliability of mining of natural aggregates. This study provides a programmatic review of the past decade of challenges and opportunities a local government in the US has experienced to implement a recycling program for their MSWI bottom ash (BA) as a construction aggregate in road materials, such as hot mix asphalt, concrete pavement, and road base. The regulatory and practical challenges in the U.S. are presented, including meeting mechanical and environmental performance requirements (e.g., strength and leaching-to-groundwater). The novel approach to overcoming these challenges include blending MSWIBA from two facilities with common aggregates, creating suitable construction materials. Interfacing with local and state agencies, such as the Department of Environmental Protection and Transportation resulted in additional testing to establish the MSWIBA as a beneficial use material and obtain essential approvals for advancing reuse opportunities. This paper synthesizes available data regarding the challenges, opportunities, and implementation of this recycling program by reviewing the experiences of an MSWI facility in the US to provide fundamental guidance to those considering similar applications.Implications: The reuse of municipal solid waste incinerator bottom ash (MSWIBA) lags in the United States (US) due to regulatory limitations and lack of precedence. This manuscript details the steps of a local government in the US to establishing a novel recycling program for their MSWIBA, including performance evaluation, regulatory interfacing, and outreach. This critical review provides a comprehensive document containing appropriate considerations required to implement similar MSWIBA recycling programs in the US and offers lawmakers, policymakers, and MSWI operators knowledge regarding opportunities and challenges associated with pursuing this avenue.