Mapping the Recycling Potential of Bottom Ashes from Waste-to-Energy Plants toward Circular Economy: Evidence from China

The
rapid expansion of waste-to-energy (WtE) facilities underscores
the need for sustainable management of incinerator bottom ash (IBA)
to advance circular economy goals. However, China’s national
potential, economic, and environmental performance in IBA recycling
remain underexplored. This study employs a data-driven machine learning
model to assess the recycling potential and spatial distribution of
various IBA components, based on a survey of 177 WtE plants and 45
IBA recovery facilities. Using life cycle assessment and cost-benefit
analysis with Monte Carlo sampling under the price uncertainties,
we evaluate IBA recycling performance across six environmental impact
categories and two economic indicators. China produces approximately
92.11 Mt of IBA annually, including 0.13 Mt of copper, 0.90 Mt of
aluminum, 3.87 Mt of iron, and 83.85 Mt of aggregates. Recycling IBA
from 1 ton of waste reduces greenhouse gas emissions by 49.34 kg CO2 equivalent, conserves 21.88 kg of fossil fuels, and mitigates
the impacts of mineral extraction and toxicity. Economically, IBA
recycling generates net revenues of 0.94–15.37 USD per ton
of waste, comparable to waste disposal fees, enhancing the financial
sustainability of WtE. This study establishes China’s first
national IBA recycling inventory, emphasizing its role in climate
mitigation, energy savings, and economic viability, and outlining
a pathway for sustainable waste management within a circular economy
framework.