An Exploration of the Impacts of Compulsory Source-Separated Policy in Improving Household Solid Waste-Sorting in Pilot Megacities, China: A Case Study of Nanjing

Empirical and simulated investigation of the solid waste reverse supply chain: A complex adaptive system perspective

Solid waste is increasing rapidly worldwide. In this study, the solid waste (household waste, construction and demolition waste and industrial waste) management systems are treated as reverse supply chain to analyze the critical operational issues based on complex adaptive system theory. At the single-layer, the complexity of the various nodes at a layer arises from rational decision-making and behavioral heterogeneity. The solid waste generation layer is employed as an example to investigate the complexity of node behavioral decisions. Regression analysis results reveal that both endogenous (Attitude, Subjective norm, and Perceived behavioral control) and exogenous factors (Economic incentive, Government supervision, Technical support) positively influence sorting behavior. The effect of Economic incentive (β=0.327P<0.001) and Attitude (β=0.249P<0.001) on sorting behavior are the largest. In the multi-layer system, different layers communicate with each other through the material and financial flows and have cross-layer impacts. An agent-based model is developed to investigate the multi-layer feedforward influence mechanism of changes in key layers (e.g., sorting rate, disposal rate) and the material and financial flows adaptive adjustment direction of the solid waste reverse supply chain. High rate of participation and accuracy of source sorting can shorten material flow paths and reduce storage and transportation costs. The increase in disposal rate encourages the transition of solid waste from backfill to resource utilization. This study provides a practice reference for solid waste reverse supply chain and related enterprises managers.

Research on the driving path of carbon inclusive system to green behavior of the public: based on procedural grounded theory and multiple intermediary model

As an emerging carbon emission reduction mechanism, the carbon inclusive system (CIS) develops an important effect in promoting public green behavior and has been piloted in some provinces and cities in China. Under this background, this paper deeply analyzes the public's attitude towards CIS and its influencing factors based on the grounded theory and 1120 questionnaires, and comprehensively discusses the action path of CIS on public green behavior by using multiple regression model, bootstrap method, and placebo test. The results show that CIS can promote the public to implement green behavior, and system operation, internal psychology, and government behavior are important factors that affect the incentive effect of CIS. Among them, incentive effect and green willingness play multiple intermediary and chain intermediary roles in the path of CIS on green behaviors. Further heterogeneity analysis shows that the influence path of CIS on green behavior is different among diverse gender groups, incentive choice preference groups, and family types. This study has reference value for improving the design of CIS and constructing diversified incentive mechanism of CIS.

Evolution of community residents' waste classification behavior based on multi-agent simulation

Municipal domestic waste (MDW) management is essential to maintain ecological security. Waste classification is seen as a solution to the urban waste dilemma. However, very few residents in China are currently involved in waste classification. Based on the public goods theory and the hypothesis of rational behavior, with the aid of GIS, this paper develops a multi-agent model to simulate the features and evolution of residents' waste classification behavior in the context of community. By comparing the percentage of those who participate in waste classification in different scenarios, various factors that may influence residents' waste classification behavior are analyzed. The simulation results show that the improvement of convenience facilities and the promotion of awareness-raising activities help enhancing residents' waste classification behavior. An increase in rewards and penalties by the government will promote residents' waste classification behavior, though this promotion is not significant. Adherent enforcers can provide a continuous incentive for residential waste classification behavior. This study provides evidence for the government and communities to develop waste classification policies and motivate residents to participate in waste classification.Implications: Municipal waste seriously restricts the survival and development of cities, and waste disposal has become a problem that plagues government managers in various countries. Waste classification is considered to be an effective way to solve the municipal waste dilemma, but currently China faces the dilemma of low residents' participation in waste classification. Through multi-agent modeling, the interaction and decision-making of urban residents in the process of waste classification are simulated, and introduce GIS to truly restore the daily classification scenes of residents. Explore the dynamic evolution of urban residents' classification behavior and the change of residents' waste classification rate under different situations to find more effective ways to improve the participation rate of residents in waste classification and give targeted and practical countermeasure suggestions. It provides decision-making reference for the formulation of governmental waste classification policies and the design of community behavior programs, and to contribute to the sustainable development of society.

Evolutionary Game Analysis of Government and Residents' Participation in Waste Separation Based on Cumulative Prospect Theory

Government and residents' participation in waste separation is a complex non-cooperative game process, and the evolutionary game can explain the behavior of participating subjects well. Considering that the traditional evolutionary game cannot satisfactorily explain the irrational psychology and risk preference factors of the participating issues, this study combines the prospect theory and evolutionary game, uses the prospect value function to supplement and improve the parameters of the evolutionary game payment matrix, and analyzes the evolutionary stabilization strategy. To verify the theoretical results, simulation experiments and impact analysis were conducted, and meaningful results were obtained: There are two stable evolutionary strategies in the system, namely higher participation benefits for residents and lower participation costs and opportunity costs, and reasonable direct benefit distribution coefficients all help to increase the participation rate of waste separation. This study can provide some scientific suggestions for the government to design and build a waste-separation system.

Influencing Factors on the Household-Waste-Classification Behavior of Urban Residents: A Case Study in Shanghai

As the process of urbanization in China continues to accelerate, the amount of domestic waste generated correspondingly increases and directly affects the living space of residents. This indirectly implies that to reduce the production of municipal solid waste and the need for garbage disposal and recycling, household-waste-classification activities by the residents are of great significance. Using Shanghai as a case study, this study investigated the influencing factors on residents’ household waste classification by conducting a survey. Statistical analysis was then adopted, which is specified below. First, this study proposed research hypotheses related to the influencing factors of residents’ domestic-waste-sorting behavior from three levels: government, society and individuals. Second, the study designed a questionnaire from five perspectives: individual characteristic variables, government, society, residents and classification behavior. Then, SPSS software was used to carry out descriptive statistical, reliability and validity assessments using ANOVA, correlation and regression analyses on the sample data obtained from the questionnaire. The results suggested that the research hypotheses were statistically significant: (1) females and residents with higher education were more likely to participate in domestic waste classification; (2) reward and punishment measures had the most significant impact on residents’ waste-classification behavior; and (3) publicity and education, classification standards, classification facilities, the recycling system, subjective norms, environmental knowledge and environmental attitudes all had a positive effect on residents’ household waste classification. Finally, based on the results of the empirical analysis, this paper provides reference suggestions for the further development of domestic waste classification in Shanghai.

The Impact of Exogenous Aerobic Bacteria on Sustainable Methane Production Associated with Municipal Solid Waste Biodegradation: Revealed by High-Throughput Sequencing

In this work, the impact of exogenous aerobic bacteria mixture (EABM) on municipal solid waste (MSW) is well evaluated in the following aspects: biogas production, leachate analysis, organic waste degradation, EABM population, and the composition of microbial communities. The study was designed and performed as follows: the control bioreactor (R1) was filled up with MSW and the culture medium of EABM and the experimental bioreactor (R2) was filled up with MSW and EABM. The data suggests that the composition of microbial communities (bacterial and methanogenic) in R1 and R2 were similar at day 0, while the addition of EABM in R2 led to a differential abundance of Bacillus cereus, Bacillus subtilis, Staphylococcus saprophyticus, Staphlyoccus xylosus, and Pantoea agglomerans in two bioreactors. The population of exogenous aerobic bacteria in R2 greatly increased during hydrolysis and acidogenesis stages, and subsequently increased the degradation of volatile solid (VS), protein, lipid, and lignin by 59.25%, 25.68%, 60.47%, and 197.62%, respectively, compared to R1. The duration of hydrolysis and acidogenesis in R2 was 33.33% shorter than that in R1. At the end of the study, the accumulative methane yield in R2 (494.4 L) was almost three times more than that in R1 (187.4 L). In addition, the abundance of acetoclasic methanogens increased at acetogenesis and methanogenesis stages in both bioreactors, which indicates that acetoclasic methanogens (especially Methanoseata) could contribute to methane production. This study demonstrates that EABM can accelerate organic waste degradation to promote MSW biodegradation and methane production. Moreover, the operational parameters helped EABM to generate 20.85% more in accumulative methane yield. With a better understanding of how EABM affects MSW and the composition of bacterial community, this study offers a potential practical approach to MSW disposal and cleaner energy generation worldwide.

Storing E-waste in Green Infrastructure to Reduce Perceived Value Loss through Landfill Siting and Landscaping: A Case Study in Nanjing, China

Electronic waste (e-waste) represents a severe global environmental issue due to the fast upgrading and updating of electronic products and the high environmental risk. Current low recycling technology, high economic cost, and weak disposal capability make it difficult for e-waste to be rendered 100% harmless. E-waste disposal requires new site-selection methods and site-saving technology to take into account the loss of public perceived value. This study attempts to improve e-waste disposal through siting and landscaping to reduce perceived value loss. The first step is to determine the minimum distance for landfill siting by surveying the minimum loss of perceived value and to use the geographic information system (GIS) to sketch the suitable landfill site thereafter. To optimize the landfill landscape, a landscape infrastructure and its filling process have been designed to reduce the environmental risk and ensure future reuse potential. The application case showed that the minimum distance is 521 m, which was sensitive to the educational level and occupation of residents. The key to landfill landscaping is the construction of isolation layers and the integration of the landfill and urban landscape. The method described in this paper is characterized by minimizing the perceived loss of value to the public, reducing environmental risks, and preserving the resource value of e-waste. This design could provide an alternative to current electronic waste processing methods.

A Practical Approach to Reduce Greenhouse Gas Emissions from Open Dumps through Infrastructure Restructuring: A Case Study in Nanjing City, China

A new environmental ban has forced the restructure of open dumps in China since 1 July 2011. A technical process was established in this study that is feasible for the upgrade of open dumps through restructuring. The feasibility of restructuring and the benefit of greenhouse gas emission reductions were assessed according to field surveys of five landfills and four dumps in Nanjing. The results showed that the daily processing capacities of the existing landfills have been unable to meet the growth of municipal solid waste (MSW), making restructuring of the landfills imperative. According to an assessment of the technical process, only four sites in Nanjing were suitable for upgrading. Restructuring the Jiaozishan landfill effectively reduced the leachate generation rate by 5.84% under its scale when expanded by 60.7% in 2015. CO2 emissions were reduced by approximately 55,000–86,000 tons per year, in which biogas power generation replaced fossil fuels Fossil fuels accounted for the largest proportion, up to 45,000–60,000 tons. Photovoltaic power generation on the overlying land has not only reduced CO2 emissions to 26,000–30,000 tons per year but has also brought in continuing income from the sale of electricity. The funds are essential for developing countries such as China, which lack long-term financial support for landfill management after closure.