Maximizing Value from Municipal Solid Waste Incineration Ash—Electrochemical and Chemical Methods for Material Recovery

In the United States, over 6.6 million tons of hazardous solid residue known as municipal solid waste incineration (MSWI) ash is generated annually by waste-to-energy (WTE) plants. These plants produce electricity and help reduce landfill volume. However, the ash produced is largely unused and typically disposed of in landfills at a cost. The economic viability of MSWI is further challenged by the decreasing price of renewable electricity. Despite this, MSWI ash holds significant potential for valuable element recovery, with an estimated value of $100-400 per ton.<br/><br/>We propose an innovative approach to recover valuable materials from MSWI ash using electrochemical and chemical processes. By harnessing electricity generated by WTE plants, our method electrolytically produces acid and base streams to facilitate material recovery and refinement. Our sequential process combines electrochemical extraction with chemical precipitation, enabling the successful recovery of elements such as copper, lead, zinc, magnesium, calcium, iron, and aluminum, along with a purified silica by-product. We have demonstrated the recovery of over 90% of the targeted elements with purities exceeding 90%. Our industry-scale techno-economic analysis indicates that this technology can extract the inherent mineral value from MSWI ash, resulting in net positive returns that far surpass the combined benefits of electricity sales and landfill cost savings.