Sludge management poses a great challenge to China's urbanization process as the number of wastewater treatment plants increases and the discharge standards are strengthened. China's sludge ...production rate is still low compared with developed countries but is undergoing a rapid growth due to increasing urbanization. Sludge management requires a systematic solution which integrates environmental effectiveness, social acceptability, and economic affordability based on a life cycle approach. In this study, we assess the environmental and economic performance of hydrothermal-pyrolysis technology (HPT), an emerging technology for sludge disposal. Climate change, human toxicity, costs, beneficial use of sludge and land occupation are used as indicators to compare HPT with conventional disposal methods, including incineration with two water contents, landfill, and compost. A particle swarm optimization (PSO) model based on the LCA results (PSO-LCA) was built to find a sustainable sludge management system in Xiamen. HPT was the most favorable scenario for sludge disposal overall, but given capacity restrictions and a trade-off between indicators, the optimal disposal proportion was for landfill to account for 9.3% of total sludge disposal, incineration with water content of 80% to account for 35.9%, HPT to account for 28.9% and compost to account for the remaining 25.9%. As further dewatering contributes a significant fraction to human toxicity effects and economic performance, the amount of dewatering should be selected based on the subsequent disposal process. The PSO-LCA method provides scientific evidence to inform decision makers to find a sustainable sludge management plan in accordance with wastewater features and socioeconomic conditions in Chinese cities.
•Environmental and economic performances of HPT are examined.•HPT has the lowest consumption of land resources, a relatively small environmental impact and high economic benefits.•HPT was found to be the most attractive method in comparison to landfill, incineration and composting.•The dewatering method should be determined by the subsequent disposal process.•The optimal proportion of sludge disposal in urban areas was proposed based on multiple indicators.
Water scarcity and pollution are grand challenges to sustainability. We developed a high-resolution wastewater input–output model for a Chinese city, Xiamen, incorporating detailed information on the ...treatment and quality of wastewater and sludge. We estimated consumption-based wastewater and sludge footprints of products (W2F and SF, respectively). Significant differences were found between the amounts of direct discharge (scope 1) and W2F (scopes 1–3), indicating the need to consider W2F in making plans for future wastewater management strategies. Reflecting its high organic content, food-related consumption was found to be a significant contributor to sludge generation. Scenario analyses were conducted to assess the effects of a shift from the traditional Chinese diet to the European diet and the anticipated industrial growth. Attempts were also made to establish links between the direct wastewater discharge of households and the final consumption of food items through human excretion, or the postconsumption footprints. It was found that the postconsumption W2F outweighed the preconsumption W2F for five out of nine food items, while the postconsumption SF outweighed the preconsumption SF in all cases except one. This research provides a scientific basis to identify the economy-wide fate of wastewater and sludge and to frame a policy for sustainable wastewater and sludge management.
Urban waste management is a complex social-ecological system that requires broader stakeholder participation and widespread environmental awareness. However, further investigation is required to ...identify interdependencies among different stakeholders and improve their interactions within the system. This research took Xiamen, a Chinese city, as a case study, which was one of 8 Chinese pilot cities that implemented waste separation in 2000 and one of the 46 key cities participating in a new separation policy since 2017. We used stakeholder analysis (SA), social network analysis (SNA) and ecological network analysis (ENA) to identify the characteristics of different stakeholders, their network structure, and the beneficiaries and contributors to the urban waste separation management (UWSM) system. The research conducted a comparison of resident’s participation before and after the new waste separation policy, as well as a comparison among different stakeholders in the new policy. The results showed that all stakeholders had a high level of satisfaction in 2017, but that satisfaction levels decreased with distance from the downtown area. Residents were more willing to participate in waste separation in 2017 than in 2012. Based on their powers and interests, stakeholders were divided into 4 categories that had different network centrality. The ecological relationships between stakeholders were mainly exploitative and competitive which may cause potential inefficiency; powerful stakeholders did not benefit the whole system and the least powerful stakeholder was the largest contributor. The combined application of these methods were complementary to help diagnose information flow problems in the socio-ecological system. Policy implications to further promote mutualism in UWSM are discussed.
Following the announcement of the China's 2020 national target for the reduction of the intensity of carbon dioxide emissions per unit of GDP by 40–45% compared with 2005 levels, Chinese provincial ...governments prepared to restructure provincial energy policy and plan their contribution to realizing the State reduction target.
Focusing on Fujian and Anhui provinces as case studies, this paper reviews two contrasting policies as a means for meeting the national reduction target. That of the coastal province of Fujian proposes to do so largely through the development of nuclear power, whilst the coal-rich province of Anhui proposes to do so through its energy consumption rate rising at a lower rate than that of the rise in GDP. In both cases renewable energy makes up a small proportion of their proposed 2020 energy structures. The conclusion discusses in depth concerns about nuclear power policy, energy efficiency, energy consumption strategy and problems in developing renewable energy.
► We review two contrasting policies as a means for meeting the national reduction target of carbon emission in two provinces. ► Scenario review of energy structure in Fujian and Anhui Provinces to 2020. ► We discuss concerns about nuclear power policy, energy efficiency, energy consumption strategy and problems in developing renewable energy.
•LCA analysis shows remanufacturing of loading machine at dealers achieves the best environment and economic benefits.•The system boundary is expanded to compare remanufacturing and original ...scenarios.•Uncertainty over climate change effects resulting from delivery distances is evaluated.•A life distribution model is built to implement a long term dynamic simulation of loading machine scrapping.•Carbon reduction is predicted over a 25-year period.
Remanufacturing is the industrial process of returning used or worn-out products to a new functional state and has been developed in China within the framework of the circular economy. Due to the recent mass production and use of construction machinery in China, there will be a huge remanufacturing potential in coming years. In this paper we take the loading machine as a case study, and use life cycle analysis to compare the environmental impacts and cost of a manufactured loading machine (S1) with its remanufactured counterparts under two return-back scenarios: remanufacturing at the original factory (S2) and at regional dealers (S3). A life distribution model was used to estimate loading machine scrappage. The results showed that climate change effects in S1, S2 and S3 were 4.4 t, 1.3 t, 0.92 t CO2-eq respectively. The financial cost in S2 and S3 was 48% and 35% respectively of the cost in S1. S3 achieves an efficient closed-loop and had the best environment and economic benefits. Carbon reduction resulting from remanufacturing is expected to peak in 2020 and 2039, and if the recycling rate is increased from 25% to 60%, the maximum CO2-eq reduction will increase by 351 million tons. Remanufacturing should play a vital role in urban carbon reduction strategies, and enterprises are capable of implementing remanufacturing through technical innovation. The quantitative environmental and economic analysis also enables remanufacturers and consumers in the market to make informed decisions.
1,1,1-Trichloroethane (1,1,1-TCA) is a typical organochloride solvent in groundwater that poses threats to human health and the environment due to its carcinogenesis and bioaccumulation. In this ...study, a novel composite with nanoscale zero-valent iron (nZVI) supported by polycaprolac-tone (PCL)-modified biochar (nZVI@PBC) was synthesized via solution intercalation and liquid-phase reduction to address the 1,1,1-TCA pollution problem in groundwater. The synergy effect and improvement mechanism of 1,1,1-TCA removal from simulated groundwater in the presence of nZVI@PBC coupling with
CN32 were investigated. The results were as follows: (1) The composite surface was rough and porous, and PCL and nZVI were loaded uniformly onto the biochar surface as micro-particles and nanoparticles, respectively; (2) the optimal mass ratio of PCL, biochar, and nZVI was 1:7:2, and the optimal composite dosage was 1.0% (w/v); (3) under the optimal conditions, nZVI@PBC + CN32 exhibited excellent removal performance for 1,1,1-TCA, with a removal rate of 82.98% within 360 h, while the maximum removal rate was only 41.44% in the nZVI + CN32 treatment; (4) the abundance of CN32 and the concentration of adsorbed Fe(II) in the nZVI@PBC + CN32 treatment were significantly higher than that in control treatments, while the total organic carbon (TOC) concentration first increased and then decreased during the culture process; (5) the major improvement mechanisms include the nZVI-mediated chemical reductive dechlorination and the CN32-mediated microbial dissimilatory iron reduction. In conclusion, the nZVI@PBC composite coupling with CN32 can be a potential technique to apply for 1,1,1-TCA removal in groundwater.
The relationship between social stratification and municipal solid waste generation remains uncertain under current rapid urbanization. Based on a multi-object spatial sampling technique, we selected ...191 households in a rapidly urbanizing area of Xiamen, China. The selected communities were classified into three types: work-unit, transitional, and commercial communities in the context of housing policy reform in China. Field survey data were used to characterize household waste generation patterns considering community stratification. Our results revealed a disparity in waste generation profiles among different households. The three community types differed with respect to family income, living area, religious affiliation, and homeowner occupation. Income, family structure, and lifestyle caused significant differences in waste generation among work-unit, transitional, and commercial communities, respectively. Urban waste generation patterns are expected to evolve due to accelerating urbanization and associated community transition. A multi-scale integrated analysis of societal and ecosystem metabolism approach was applied to waste metabolism linking it to particular socioeconomic conditions that influence material flows and their evolution. Waste metabolism, both pace and density, was highest for family structure driven patterns, followed by lifestyle and income driven. The results will guide community-specific management policies in rapidly urbanizing areas.
China's National Plan on Implementation of the 2030 Agenda for Sustainable Development identified the upgrading of urban shantytowns, urban villages, and dilapidated houses as an important initiative ...to implement the Sustainable Development Goal (SDG) 11.1. However, informal housing being used as temporary housing by low-income families (especially in megacities) has resulted in informal settlements that are usually densely populated, dilapidated, and disorganized. Identifying targets based on deep learning and single very high-resolution images remains a challenging task. Here, we used multi-source geographic information data and machine-learning methods to identify and compare the distribution of densely populated‒informal settlements (DPISs) and measured population ratios within the urban areas of three Chinese first-tier cities: Beijing, Shanghai, and Guangzhou. Our results indicate that DPISs occupy 1.98%, 0.67%, and 3.95% of the total area in these study regions, with population densities of 42,800 people/km
2
, 7,100 people/km
2
, and 20,800 people/km
2
, respectively. Further, significant variability existed in the distribution of DPISs, population ratios, and composition of the study areas. DPISs reflected the rapid urbanization process in China and the planning of the city, which can be used as an indicator of sustainable urban development in China.
Localizing SDGs indicators to study areas and incorporating regional variations and specific characteristics enhanced the understanding of their role in regional sustainable development.
DPISs were introduced in this study; the similarities and differences were made between DPIS and SDG indicators.
Contrasting distribution patterns of DPISs in Beijing, Shanghai, and Guangzhou revealed distinct regional disparities and urban development dynamics.
Integration of multi-source remote sensing data enabled comprehensive analysis of complex features and spatial patterns of DPISs.
Exploration of the intricate relationship between DPISs and urbanization unveiled challenges and potential opportunities for inclusive urban development.
Waste management is an evolutionary system, but few studies have explored how and why public willingness to participate in waste separation changes, or explored possible paths to increase residents’ ...willingness to participate. This paper took Shanghai as a case study of a city that has experienced recent environmental policy change to embrace an evolutionary feedback perspective. The results showed that after the policy implementation, resident’s satisfaction with waste management increased by only 5.3%, and participation willingness actually decreased by 5.4%. A Geodetector model showed that both separation attitude and knowledge are highly important both before and after policy implementation. Residents’ satisfaction with community waste management showed the largest increase soon after the policy implementation while the importance of time occupied by waste separation dropped significantly. Policy simulation by a system dynamics model showed that the community-driven scenario was able to achieve 95% participation 2 years earlier than baseline scenario. Improving community satisfaction by improving waste management infrastructure can offset the adverse effects of an increased number of waste categories. The study helps to quantify the interaction between institutional change and public participation and find effective measures to maintain public participation in environmentally-friendly behaviors.
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•Resident’s participation willingness decreased by 5.4% after policy implementation.•Factors influencing participation willingness changed after policy implementation.•Community-driven scenario promoted resident’s participation in 2 years earlier.•Increasing the number of waste categories reduced participation willingness.•Increasing satisfaction offset the effect of increasing number of waste categories.
► We present a spatial planning framework to identify the appropriate developing areas of biomass energy at regional level. ► The methodology performs detailed technical, economic and priority ...analysis of each supply area in the study area. ► The methodology can support the local authorities to define and implement a strategy for future biomass energy development.
Effective spatial planning is crucial for cost-effectively and sustainably developing biomass energy resources due to the diffuse nature of biomass and high transportation cost. Using the spatial analysis technology, economic models and scenario analysis, this paper presents a spatial planning framework to identify the appropriate developing areas of biomass energy at regional level. The methodology is applied in a case study of Fujian Province, China. Firstly, spatial distribution of two kinds of biomass resources and the technical potential, i.e. the amount of power generation from agricultural and forestry residues in each supply area, were estimated by incorporating the spatial data and the statistical data. The results indicate that total technical potential of agricultural and forestry residues is estimated at 25.13TWhy−1, equivalent to approximately 19% of total electricity consumption in Fujian in 2010. In the second step, the economic analysis assesses the cost of biomass generation for each supply area on the basis of current market conditions. Ranking of the supply areas is then performed by using the priority development index (PDI), which can measure the priority of each biomass supply area by combining several influencing indicators. Finally, the selection of supply areas for power plants can be carried out according to its order in PDI until the total planed capacity in the region is met. The priority of the subregions and the corresponding cost of biomass generation for different planning scenarios can be explicitly visualized. The methodology can be applied to a wide area and can support the local authorities to define and implement a strategy for future biomass energy development.
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