[Spatial Correlation Structure and Influencing Mechanism of Development Level of Zero-waste Cities in China].

Based on the entropy weight TOPSIS method to measure the development level of "zero-waste cities" in China from 2004 to 2021, the social network analysis method and spatial Durbin model were used to explore the spatial correlation network structure and impact mechanism of the development level of "zero-waste cities." The results showed that： ① The development level of "zero-waste cities" was generally on the decline in the whole country and the eastern and central regions. However, it was on the rise in the western regions. ② The spatial correlation of the development level of "zero-waste cities" presented a core-edge structure, with an overall upward trend in network density and a stable state in the overall network. ③ Beijing, Shanghai, Jiangsu, Zhejiang, Fujian, and Guangdong were at the center and dominant position of the network. ④ Beijing, Tianjin, Shanghai, and Jiangsu belonged to the "net benefit" sector； Zhejiang, Fujian, and Guangdong belonged to the "broker" sector； and the other provinces belonged to the "net overflow" sectors. ⑤ The level of urbanization, economic development, technological innovation, foreign investment, environmental regulations, government intervention, and population size had a significant impact on the development level of "zero-waste cities" in local or neighboring provinces, respectively. The research results can provide a reference for the proposal of policies for constructing and coordinating the development of "zero-waste cities" in various regions.

Decreasing Greenhouse Gas Emissions from the Municipal Solid Waste Sector in Chinese Cites.

Municipal solid waste (MSW) management systems play a crucial role in greenhouse gas (GHG) emissions in China. Although the government has implemented many policies to improve the MSW management system, the impact of these improvements on city-level GHG emission reduction remains largely unexplored. This study conducted a comprehensive analysis of both direct and downstream GHG emissions from the MSW sector, encompassing sanitary landfill, dump, incineration, and biological treatment, across 352 Chinese cities from 2001 to 2021 by adopting inventory methods recommended by the Intergovernmental Panel on Climate Change (IPCC). The results reveal that (1) GHG emissions from the MSW sector in China peaked at 70.6 Tg of CO2 equiv in 2018, followed by a significant decline to 47.6 Tg of CO2 equiv in 2021, (2) cities with the highest GHG emission reduction benefits in the MSW sector were historical emission hotspots over the past 2 decades, and (3) with the potential achievement of zero-landfilling policy by 2030, an additional reduction of 203.7 Tg of CO2 equiv is projected, with the emission reduction focus toward cities in South China (21.9%), Northeast China (17.8%), and Southwest China (17.3%). This study highlights that, even without explicit emission reduction targets for the MSW sector, the improvements of this sector have significantly reduced GHG emissions in China.

How does the digital economy affect the provincial "zero-waste city" construction? Evidence from China.

The digital economy is playing a crucial effect in the field of environmental governance. Digital and intelligent management is an essential means to fully realize the "zero-waste city" construction. The present paper investigates the impact of digital economy on China's provincial "zero-waste city" construction. The results indicate that digital economy can contribute to "zero-waste city" construction. The digital economy has a positive nonlinear effect on the construction of "zero-waste city," but the marginal effect is diminishing. The digital economy can facilitate "zero-waste city" construction by improving industrial structure upgrading and green technology innovation. Heterogeneity analysis reveals that digital economy contributes to the construction of "zero-waste city" in the eastern and western regions and high-level environmental regulation regions, while this impact is insignificant in the central region and low-level environmental regulation regions. The digital economy exerts the most significant positive influence on waste resource recycling followed by waste final disposal and then waste reduction at the source. These findings underscore the effect of digital economy in fostering "zero-waste city" construction and promoting sustainable waste management. The present study provides new ideas for the "zero-waste city" construction in emerging developing countries such as China.

Periodic injection of liquefied kitchen and food waste in municipal solid waste: Effects on leachate and gas generation.

With continuous advancements in the zero-waste strategy in China, transportation of fresh municipal solid waste to landfills has ceased in most first-tier cities. Consequently, the production of landfill gas has sharply declined because the supply of organic matter has decreased, rendering power generation facilities idle. However, by incorporating liquefied kitchen and food waste (LKFW), sustainable methane production can be achieved while consuming organic wastewater. In this study, LKFW and water (as a control group) were periodically injected into high and low organic wastes, respectively. The biochemical characteristics of the resulting gas and leachate were analyzed. LKFW used in this research generated 19.5-37.6 L of methane per liter in the post-methane production phase, highlighting the effectiveness of LKFW injection in enhancing the methane-producing capacity of the system. The release of H2S was prominent during both the rapid and post-methane production phases, whereas that of NH3 was prominent in the post-methane production phase. As injection continued, the concentrations of chemical oxygen demand, 5-d biological oxygen demand, total organic carbon, ammonia nitrogen, total nitrogen, and oil in the output leachate decreased and eventually reached levels comparable to those in the water injection cases. After nine rounds of injections, the biologically degradable matter of the two LKFW-injected wastes decreased by 8.2 % and 15.1 %, respectively. This study sheds light on determining the organic load, controlling odor, and assessing the biochemical characteristics of leachate during LKFW injection.

Assessing the policy benefits of constructing "Zero-waste Cities" in China: From the perspective of hazardous waste lifecycle management.

Based on China's quasi-natural experiment of constructing "Zero-waste Cities", this study assessed its policy benefits on hazardous waste lifecycle management. Utilizing the theory of difference-in-differences analysis, the study quantifies the net benefits of the policy in 10 pilot cities using an average treatment effect formula, and the results indicate a reduction of 162,900 tons/year in waste generation, an increase of 2.3 % in utilization and disposal rate, and a decrease of 28,200 tons/year in end-of-pipe storage. By constructing a regression model and employing robustness tests such as changing control variables, substituting the explained variable, re-matching control groups, and random assignment of pilot sites, the study confirms that the significant policy benefits primarily lie in source reduction, with a reduction intensity of approximately 1.73 tons/100 million yuan of industrial GDP. Additionally, by applying the mixed-effects model and mediation-analysis model, the study finds that the policy benefit of source reduction exhibits a lag effect, and during the pilot period, the main approach to achieving the benefit was through enhancing cleaner production in companies rather than adjusting industrial structures in cites.

Evaluating the resource recovery efficiency of garbage removal and disposal in Taiwan.

All countries recognize the importance of enhancing circular resource utilization and promoting zero waste in order to achieve a circular economy. This study focuses on 22 counties (cities) in Taiwan and analyses the relationship between changes in resource recovery efficiency and productivity over an 8-year period (2011-2018) using the super efficiency directional distance function and total factor productivity. The results indicate that the average total efficiency of resource recovery in the 22 counties (cities) is 1.3951, with 17 counties (cities) exceeding 1. The average gross productivity of resource recovery is 1.0417, and only four counties have a gross productivity of less than 1. Despite having more administrative resources, municipalities directly under the central government have a slightly lower average total efficiency of resource recovery (1.1464) than non-municipalities (1.4885). To improve efficiency, the government should allocate resources rationally and upgrade technology. The study's findings can serve as a reference for the 22 counties (cities) in Taiwan and provide guidance for municipal governments worldwide in developing policies related to resource recovery.

The rising phenomenon of circular cities in Japan. Case studies of Kamikatsu, Osaki and Kitakyushu.

Japan has a culture of appreciating nature, but Japan is the 7th biggest waste producer of OECD (Organisation for Economic Co-operation and Development) countries, as it only recycles 19,6 %, deposits 1 % in landfills, and incinerates the rest. Japan also has one of the lowest rates (20 %) of renewable energy of OECD countries, and recently has decided to reactivate nuclear power plants. In contrast, cases of local circular economy initiatives are increasing in Japan. This suggests an opportunity for progress towards more ambitious circular economy goals. Circular Cities (CC) embrace the principles of the circular economy (CE) by managing resources to minimize waste, maximize efficiency, and promote sustainability. The idea of circular cities is taking hold in the country. This work assesses in a top-down approach CC from a general perspective considering the current state of the art, and then, its application to the Japanese scheme to be contrasted within three particular case studies. CC in Japan represents a holistic and sustainable approach that enhances well-being and the economy by using CE principles. It incorporates Japanese cultural attributes and the necessary stakeholders' involvement to maximize closed loops, reduce resource consumption, and establish a regenerative society. The paper recognizes current progress towards circularity in Japan's cities, towns, and villages, even though they may not call themselves "circular cities" per se. The paper proposes a definition for circular cities specifically for Japan. It analyses three case studies: Kamikatsu, Osaki, and Kitakyushu, urban areas with very different circumstances as examples of circular cities, with the final goal to provide recommendations to policymakers to help increase the circular cities phenomenon.

Techno-economic analysis and optimization of near-zero energy and emission neighborhoods using biomass waste.

The present study aims to simulate and design a near-Zero Energy neighborhood in one of the most significant industrial cities for reducing greenhouse gas emissions. For this building, biomass wastes are used for energy production, and also energy storage is provided using a battery pack system. Additionally, the Fanger model is used to assess the passengers' thermal comfort, and information on hot water usage is given. The transient performance of the aforementioned building is tested for one year using TRNSYS software, which was employed for this simulation. Wind turbines are considered electricity generators for this building, and any extra energy generated is stored in a battery pack for usage when the wind speed is insufficient and electricity is needed. Hot water is created using a biomass waste system and is kept in a hot water tank after being burned using a burner. A humidifier is utilized to ventilate the building, and a heat pump provides both the building's heating and cooling needs. The produced hot water is used to supply the residents' hot water. In addition, The Fanger model is considered and used for the assessment of occupants' thermal comfort. Matlab software is a powerful software used for this task. According to the findings, a wind turbine with a 6 kW generation capacity may supply the building's power needs while also charging the batteries beyond their initial capacity, and the building will have zero energy. Additionally, biomass fuel is used to give the building the required water which should be hot. On average, 200 g of biomass and biofuel are used per hour to maintain this temperature.

Introducing a classification framework to urban waste policy: Analysis of sixteen zero-waste cities in China.

Chinese cities are experiencing rapid urban development while facing severe challenges of environmental pollution. China's central government has proposed several policies to reduce urban waste. However, little is known about the adoption of these policies. Here, we raise the question how can circular policies be classified, and how can this classification be applied to cities in China that wish become zero-waste cities? We develop a framework to classify urban waste policies according to: (a) the "5R" principles ("Rethink", "Reduce", "Reuse", "Recycle", and "Recover"), (b) four types of waste (industrial, agricultural, municipal, and hazardous) and (c) six types of policy instruments (legal, economic, network, communication, innovation and projects). We use this framework to analyze urban waste policies implemented by sixteen zero-waste demonstration projects in China. The present study emphasizes combinations of policy instruments, "R" strategy and waste type in the implementation of zero-waste policies. We find that the "Rethink", "Reduce", and "Recycle" principles have been widely implemented by local authorities in contrast to the principles "Reuse" and "Recover". Local governments address waste management by embracing regulations, innovation instruments, and project arrangements, while network-based, economic, or communicative policy instruments are used less often. Based on the results we suggest that local governments embrace a comprehensive approach to the use of the "5R" principles and deploy a diverse portfolio of policy instruments.

Waste to energy: A review of biochar production with emphasis on mathematical modelling and its applications.

United Nations charter to build a sustainable future has paved the way for the introduction of the Sustainability Development Goals (SDGs) at a global forum. In particular, SDG 11 is aligned with the idea of developing cities and communities that provide quality human life, by attaining net-zero discharge and self-sustainability. In line with the efforts of the global community, biochar has emerged as a viable solution due to its ability to convert waste into value. Finding applications in a spectrum of domains, biochar is being studied for use as an adsorbent, a co-catalyst to promote industrial-grade reactions and as a feed for fuel cells. Moreover, the inclusion of biochar as a soil enhancement material advocates the implementation of closed-loop nutrient cycles. Hence, it is imperative to have a proper understanding of the biomass characteristics, the hydrothermal treatment and the process parameters to be adopted for the production of char in order to identify biomass feedstock based on the application. The current work provides insight into the key factors and conditions employed for the production of biochar based on the plethora of applications. In order build a basic framework to aid in the production of char, the development of a statistical correlation was undertaken to determine the feed and optimum process parameters for the production of biochar based on its applications.

Nitrogen management in farming systems under the use of agricultural wastes and circular economy.

Population growth leads to an increase in the demand for energy, water, and food as cities grow and urbanize. However, the Earth's limited resources are unable to meet these rising demands. Modern farming practices increase productivity, but waste resources and consume too much energy. Agricultural activities occupy 50 % of all habitable land. After a rise of 80 % in 2021, fertilizer prices have increased by nearly 30 % in 2022, representing a significant cost for farmers. Sustainable and organic farming has the potential to reduce the use of inorganic fertilizers and increase the utilization of organic residues as a nitrogen (N) source for plant nutrition. Agricultural management typically prioritizes nutrient cycling and supply for crop growth, whereas the mineralization of added biomass regulates crop nutrient supply and CO2 emissions. To reduce overconsumption of natural resources and environmental damage, the current economic model of "take-make-use-dispose" must be replaced by "prevention-reuse-remake-recycle". The circular economy model is promising for preserving natural resources and providing sustainable, restorative, and regenerative farming. Technosols and organic wastes can improve food security, ecosystem services, the availability of arable land, and human health. This study intends to investigate the nitrogen nutrition provided by organic wastes to agricultural systems, reviewing the current state of knowledge and demonstrating how common organic wastes can be utilized to promote sustainable farming management. Nine waste residues were selected to promote sustainability in farming based on circular economy and zero waste criteria. Using standard methods, their water content, organic matter, total organic carbon, Kjeldahl nitrogen, and ammonium levels were determined, along with their potential to improve soil fertility via N supply and technosol formulation. 10 % to 15 % of organic waste was mineralized and analysed during a six-month cultivation cycle. Through the results, the combination of organic and inorganic fertilization to increase crop yield is recommended, as is the search for realistic and practical methods of dealing with massive amounts of organic residues within the context of a circular economy.

Decarbonization in waste recycling industry using digitalization to promote net-zero emissions and its implications on sustainability.

Digitalization and sustainability have been considered as critical elements in tackling a growing problem of solid waste in the framework of circular economy (CE). Although digitalization can enhance time-efficiency and/or cost-efficiency, their end-results do not always lead to sustainability. So far, the literatures still lack of a holistic view in understanding the development trends and key roles of digitalization in waste recycling industry to benefit stakeholders and to protect the environment. To bridge this knowledge gap, this work systematically investigates how leveraging digitalization in waste recycling industry could address these research questions: (1) What are the key problems of solid waste recycling? (2) How the trends of digitalization in waste management could benefit a CE? (3) How digitalization could strengthen waste recycling industry in a post-pandemic era? While digitalization boosts material flows in a CE, it is evident that utilizing digital solutions to strengthen waste recycling business could reinforce a resource-efficient, low-carbon, and a CE. In the Industry 4.0 era, digitalization can add 15% (about USD 15.7 trillion) to global economy by 2030. As digitalization grows, making the waste sector shift to a CE could save between 30% and 35% of municipalities' waste management budget. With digitalization, a cost reduction of 3.6% and a revenue increase of 4.1% are projected annually. This would contribute to USD 493 billion in an increasing revenue yearly in the next decade. As digitalization enables tasks to be completed shortly with less manpower, this could save USD 421 billion annually for the next decade. With respect to environmental impacts, digitalization in the waste sector could reduce global CO2 emissions by 15% by 2030 through technological solutions. Overall, this work suggests that digitalization in the waste sector contributes net-zero emission to a digital economy, while transitioning to a sustainable world as its social impacts.

Comparative analysis of the contribution of municipal waste management policies to GHG reductions in China.

Waste generation and disposal have been a global issue for decades. The total global greenhouse gas (GHG) emissions in 2019 were 49,758 MtCO2e with waste disposal accounting for 3.2%. With rapid urbanization trends, municipal solid waste (MSW) has become a global challenge which needs to be addressed. A large fraction of MSW such as food wastes, e-waste among others still ends up with unregulated dumps or openly burned in low-income countries. As a response, China initiated the 'zero-waste' pilot program which has been running since 2019. To investigate the potential contribution of MSW management to GHG reductions, this study selected four 'zero-waste' cities in China, namely Shenzhen, Panjin, Xining and Tongling, as case studies to assess the impacts of different MSW management policies on GHG reductions from 2015 to 2019. Results demonstrated that Shenzhen city achieved progress in reducing GHGs, which decreased by more than 40% between 2015 and 2019. This study provides policy recommendations and waste management approaches and practices to optimize MSW management and reduction of GHGs.

How does the "Zero-waste City" strategy contribute to carbon footprint reduction in China?

The "Zero-waste City" program and carbon peak plan are currently vital environmental strategies in China. Solid waste management systems are closely related to greenhouse gas emissions, and "Zero-waste City" programs are highlighted because of their great potential for carbon footprint reduction and pollution mitigation. However, a knowledge gap remains in terms of quantifying the carbon footprint when implementing "Zero-waste City" programs. Here, we developed a methodology for accounting for the carbon footprint of a solid waste management system, and Ningbo city, which is one of the first demonstration "Zero-waste Cities" in China, was chosen as the study case. The material flow and carbon footprint of construction and demolition waste, industrial waste, hazardous waste, sludge, and municipal solid waste were analyzed. The results show that the carbon footprint of the solid waste management system in Ningbo city was -1679.9 Gg CO2_eq in 2018, which can be divided into 3472.5, 1131.3, and -6283.8 Gg CO2_eq by Scopes 1, 2, and 3, respectively. According to the scenario analysis, the SWMS in Ningbo city can achieve a carbon footprint reduction potential of at least 5771.5 Gg CO2_eq by 2025, by implementing the "Zero-waste City" strategy. This suggests that waste minimization, construction and demolition waste recycling, and municipal solid waste recycling are the most effective measures for carbon footprint reduction.

The waste ban in China: what happened next? Assessing the impact of new policies on the waste management sector in China.

The 2017 ban on the waste import and new policies for the waste management sector in mainland China had wide-spread impact. After decades of poor environmental and public health impacts from the sector, a study is needed which focuses on policies updates and waste management. This provides a direction for the survival of local waste management industries and consider similarities with the ban promulgated in China on the restriction of waste import from other countries. We review the waste management situation in China before national legislation prevented the import of waste, highlight the status of landfill mining in China, and review the dynamics of domestic policies before and after the promulgation of the ban in China. The impact of the COVID19 pandemic on the waste management system is starting to emerge, providing both challenges and opportunities for the sector in China. We see the impact of the ban on the range of imported waste and domestically generated materials. The ban results in price increases for domestic recycling that forces companies to introduce more formal recycling processes and to drive the consumption behaviours to more reasonable and environmentally friendly options. The driver in China is to reduce pollution in the environment and improve health, but a negative impact has been from increased landfill mining which has impeded the original aim of the waste ban and requires further technological development. The dynamic of domestic policies in China shows higher level of activity of updates and revisions or introduction of new policies from 2015 onwards and the concept of 'zero waste cities' brings new hope for improvement of the Chinese waste management system. The pandemic also suggests an important step to establish sustainable management systems despite evidence of increased "fly-tipping". The rebound of the waste ban may have stimulated in the short term negative impacts on local environments both in China and internationally.

Win-Win: Anthropogenic circularity for metal criticality and carbon neutrality.

Resource depletion and environmental degradation have fueled a burgeoning discipline of anthropogenic circularity since the 2010s. It generally consists of waste reuse, remanufacturing, recycling, and recovery. Circular economy and "zero-waste" cities are sweeping the globe in their current practices to address the world's grand concerns linked to resources, the environment, and industry. Meanwhile, metal criticality and carbon neutrality, which have become increasingly popular in recent years, denote the material's feature and state, respectively. The goal of this article is to determine how circularity, criticality, and neutrality are related. Upscale anthropogenic circularity has the potential to expand the metal supply and, as a result, reduce metal criticality. China barely accomplished 15 % of its potential emission reduction by recycling iron, copper, and aluminum. Anthropogenic circularity has a lot of room to achieve a win-win objective, which is to reduce metal criticality while also achieving carbon neutrality in a near closed-loop cycle. Major barriers or challenges for conducting anthropogenic circularity are deriving from the inadequacy of life-cycle insight governance and the emergence of anthropogenic circularity discipline. Material flow analysis and life cycle assessment are the central methodologies to identify the hidden problems. Mineral processing and smelting, as well as end-of-life management, are indicated as critical priority areas for enhancing anthropogenic circularity. Electronic Supplementary Material: Supplementary material is available in the online version of this article at 10.1007/s11783-023-1623-2 and is accessible for authorized users.

How publications and patents are contributing to the development of municipal solid waste management: Viewing the UN Sustainable Development Goals as ground zero.

Academia and industry have strengthened each other under the guidelines of regulatory institutions to contribute theoretical knowledge and practical solutions for society, which can be presented in a combination of publishing research and filing patents. In the case of municipal solid waste management (MSWM), a great transformation from a linear to a circular view has been in process. In this study, we investigated the role of the United Nations Sustainable Development Goals (SDGs) in MSWM-related development and transformation. The authors examined the contributions of academic and industrial spheres to MSWM in the past 70 years by examining Web of Science's Core Collection and Derwent Innovations Index. The results showed that SDGs not only accelerated the research on MSWM but also pulled MSWM-related knowledge and innovation to new fronts that focus on sustainable and circular methods. Based on the current findings, we derived implications for academia, industry, and policymakers.

Assessment of maternal services in China based on WHO's comprehensive evaluation model.

BACKGROUND: To understand the trend of equalization in maternal services and to guide policy-makers regarding resource allocation and public health policy in China. METHODS: Twelve indicators, including maternal services needs, utilization, and resource allocation, were collected from China Health Statistical Year Book 2010 and 2020. WHO's comprehensive evaluation model and the non-integral Rank Sum Ratio (RSR) method were used to analyze, rank, and categorize maternal services of 31 provinces (cities, autonomous regions) in China. RESULTS: All provinces (cities, autonomous regions) are grouped into relative balance areas, low input areas, resource shortage areas, overutilization areas, and resource waste areas. In 2019, there were 18 provinces (cities, autonomous regions) in the relative balanced area, and more than one-half had achieved equal development. Compared to 2009, the resource shortage area decreased from three to zero, and the resource waste area increased from four to six. Among the provinces (cities, autonomous regions) with a type change compared with 2009, eight changed to a relative balance areas, and four showed an improvement. CONCLUSION: Under the policy guidance of promoting the equalization of public health services, maternal services are gradually realized. However, several provinces (cities, autonomous regions) still have problems such as the mismatch between resource input and health needs, resource waste, over-utilization, etc. Therefore, specific policies should be formulated according to the actual types to promote the transformation into equalization regions.

Municipal solid waste management for reaching net-zero emissions in ASEAN tourism twin cities: A case study of Nan and Luang Prabang.

Waste generation rates have increased with rapid population and economic growth worldwide, especially in tourism cities. Nan Province and Luang Prabang (LPB) are twin cities that have been popular tourist destinations. The impact of unmanaged waste threatens the socioeconomic environment in both places. Three waste management scenarios were developed to achieve net-zero greenhouse gas (GHG) emissions from the municipal solid waste (MSW) sector in Nan and LPB by 2030. Sensitivity and benefit-cost (B/C) analyses were performed, and alternative scenarios were proposed. With the use of available waste management technology, all developed scenarios in both locations could achieve net-zero emissions within the difference contexts of the city such as waste composition. From this study, on-site waste sorting is the key for waste management to achieve net-zero emissions. Sensitivity analysis revealed that, with an average carbon price of 28.42 USD/tCO2e, all scenarios in Nan and LPB were feasible, except for scenario 2 (off-site waste sorting) in LPB. This study found that it would be challenging but achievable to reach the net-zero emissions target. The challenge includes the increased on-site waste separation rate and raising public awareness concerning municipal solid waste management as well as its importance for effective waste management. These developed scenarios show a pathway for the waste sector to achieve net-zero emissions by 2030 with available waste management technology in Nan and Luang Prabang, and the possibilities for other locations facing similar situations.

A Study on the Willingness of Industrial Ecological Transformation from China's Zero Waste Cities Perspective.

Based on the practice of a circular economy, China officially put forward the goal of building a "Zero Waste City" in 2018 and has formulated a series of measures to promote energy savings and emissions reduction in various sectors among which industry has received key attention due to its long-term high energy consumption and high pollution. The growth of an urban economy cannot be supported by industry, but the high energy consumption and high pollution of industry have become the keys to urban environmental management, and the need for ecological transformation of industry is very urgent. Based on the construction background of zero waste cities in China, this study analyzes the transformation factors of industrial producers' willingness to make ecological transformation. The factors that influence industrial producers to make ecological transformation are perception of participation, perception of cost, perception of identity, and perception of government intervention. These factors have a positive moderating effect on the adoption of transformation strategies by industrial producers among which the perception of government involvement also plays a mediating role and has an important influence on the promotion of active ecological transformation by industrial producers.