Exploring the coevolution of residents and recyclers in household solid waste recycling: Evolutionary dynamics on a two-layer heterogeneous social network.

China's household solid waste recycling system has long faced the challenge of recycling formalization. This process is affected by the complexity of the interdependence of the recycler and resident decisions. The aim of this study was to gain a better understanding of the coevolution of residents' and recyclers' recycling decisions. To this end, this study applied agent-based modeling and network-based evolutionary game methods to construct evolutionary game models based on a two-layer social network. The two layers of heterogeneous social networks depicted the connections between residents and recyclers, respectively. Residents and recyclers choose either formal or informal recycling strategies within layers according to evolutionary game theory. Waste flows and cash flows underlie the interdependent coevolution between the two layers. Using this model, the effects of resident subsidies, recycler subsidies, and regulatory policies on the coevolution of residents and recyclers were simulated. The results showed that the impact of policies on recycling systems relies on long-term social interaction. The trends in the strategic evolution of residents and recyclers were similar, and emerged from their interdependence and mutual influence. Resident-oriented subsidy incentives can promote formal recycling stably and positively. However, recycler subsidies and regulatory policies have opposite marginal promotion effects, as is reflected by the fact that the evolution of formal recycling is insensitive to high recycler subsidies and sensitive to high-intensity regulatory policies. These findings provide a more comprehensive insight into the development of recycling systems and inform the design of waste management policies.