Role of rural solid waste management in non-point source pollution control of Dianchi Lake catchments, China

In recent years, with control of the main municipal and industrial point pollution sources and implementation of cleaning for some inner pollution sources in the water body, the discharge of point source pollution decreased gradually, while non-point source pollution has become increasingly distressing in Dianchi Lake catchments. As one of the major targets in non-point source pollution control, an integrated solid waste controlling strategy combined with a technological solution and management system was proposed and implemented based on the waste disposal situation and characteristics of rural solid waste in the demonstration area. As the key technology in rural solid waste treatment, both centralized plant-scale composting and a dispersed farmer-operated waste treating system showed promise in rendering timely benefits in efficiency, large handling capacity, high quality of the end product, as well as good economic return. Problems encountered during multi-substrates co-composting such as pathogens, high moisture content, asynchronism in the decomposition of different substrates, and low quality of the end product can all be tackled. 92.5% of solid waste was collected in the demonstration area, while the treating and recycling ratio reached 87.9%, which prevented 32.2 t nitrogen and 3.9 t phosphorus per year from entering the water body of Dianchi Lake after implementation of the project.     

城市生活垃圾处理技术现状与管理对策

近年来,我国城市生活垃圾产生量每年以约10%的速度迅猛增长,而城市生活垃圾处理能力发展相对滞后。客观评述城市生活垃圾常用的填埋、焚烧、堆肥3种处理技术的优缺点和在国内的应用现状,并针对城市生活垃圾在收运、处理以及管理等环节中存在的突出问题,提出了明确的建议与措施：首先,完善相关法规政策,实施分类收集,加强源头控制;其次,创新管理体制,推行市场化运作机制,政府加强政策引导和监督;再次,按照＂谁污染,谁付费＂的原则,建立健全垃圾收费体系;最后,充分利用各种媒介,加大宣传力度,提高公众环保意识。同时,还探讨了城市生活垃圾处理技术发展的趋势。焚烧处理将是今后一段时期我国最有发展潜力的技术,气化熔融焚烧技术是一种高效资源化、污染物接近零排放的新型焚烧技术;生物反应器填埋技术可减少渗滤液处理量、降低垃圾处理成本,具有广阔的发展前景;堆肥技术可作为焚烧或填埋之前的预处理手段;城市生活垃圾综合处理集多种处理技术的优点于一体,在节约处理成本,提高经济效益的同时,实现了垃圾的减量化、资源化、无害化,是未来我国生活垃圾处理的优先发展方向。     

Industrial solid waste flow analysis of eco-industrial parks: implications for sustainable waste management in China

Sustainable waste management in the industrial ecology perspective brings enormous challenges to the existing methodology of waste analysis at the industrial park (IP) scale. In this study, a four-step method was proposed for industrial solid waste (ISW) flow analysis of eco-industrial parks (EIPs) and applied to two IPs in eastern China. According to a park-wide census of 619 industrial enterprises and 105 questionnaires by a survey from 2006 to 2008, the results indicated that: 1) at the enterprise scale, more than 60% of enterprises were small-ISW-generation enterprises which encountered great difficulties on effective waste management; 2) at the IP scale, though the two IPs have set up their own environmental management systems and passed the ISO 14001 certification, the efficiencies of the ISW management systems have yet to be improved in the industrial ecology perspective; and 3) at the regional scale, more than 97% of ISW flowed within the provincial region, indicating that the provincial governments prevented the wastes from flowing into their own “back yard”. Effective waste management should be placed in a broader perspective. Approaches to sustainable waste management may include wastes exchange, efficient waste and information flow, virtual EIP, waste minimization clubs and regionalization of waste management.     

Municipal solid waste management in Dalian: practices and challenges

The fast growing of urban areas in developing countries has brought serious problems on municipal solid waste (MSW) management. It will be rational to adopt an integrated approach to deal with such a challenge so that the overall eco-efficiency of MSW management could be improved. To better examine how attributes of integrated MSW management are being interpreted and put into practice, and to explore what changes should be made to improve the application of integrated MSW management, we employ a case study method so that lessons learned could be used to inform initiatives in other cities and the potential solution may offer feasible strategies. The case study city is Dalian, a typical seaport city with fast growing rate in economy. The outcomes of this case study show us that fragmented management structure, ineffective and inefficient enforcement of relevant regulations, backward technologies, limited financial resources and lack of public participation are main barriers for the implementation of integrated MSW management. Consequently, in order to overcome these barriers, we propose an integrated management framework on MSW management, aiming to maximize the overall eco-efficiency of MSW management.     

Carbon discharge through municipal solid waste in Haikou,China

With rapid urban development, municipal solid waste (MSW) has become a pressing issue. Estimation of carbon discharge through municipal solid waste provides a way to assess environmental load of solid waste from the viewpoint of the carbon cycle. With few studies on carbon research and provides insights into human impacts on the carbon cycle. Based on a comprehensive fieldwork investigation of a typical Chinese tourist city – Haikou City, Hainan Island – the characteristics of MSW carbon discharge and human activities that influenced it were analysed. The results indicated that, in 2001, the total carbon discharge from 261.9 Gg of MSW was 105.1 GgC per year, and 174.6 kgC per capita per annum. Carbon is discharged in the form of food scraps (24%), plastics (20%), wood (17%), fabrics (14%), paper (13%), and dust and stone (12%). If landfill received all the waste, 4.7% of MSW carbon would be transformed into methane, with a value of 4.9 GgC. Between 1991 and 1999, Haikou's per capita MSW carbon discharge increased by 59.9%, and total MSW carbon discharge increased by 124.9%. MSW carbon discharge in Haikou is significantly affected by the growth of residential expenditure and urbanisation. Local characteristics of tourism also influence Haikou's MSW carbon discharge, not only in terms of its yearly variation, but also its monthly variation. Integrating data on carbon discharge with carbon consumption will provide a systematic view of the carbon metabolism in urban ecosystems, and further insights into the generation of urban environmental pollution.     

State-of-the-art applications of machine learning in the life cycle of solid waste management

● State-of-the-art applications of machine learning (ML) in solid waste (SW) is presented. ● Changes of research field over time, space, and hot topics were analyzed. ● Detailed application seniors of ML on the life cycle of SW were summarized. ● Perspectives towards future development of ML in the field of SW were discussed. Due to the superiority of machine learning (ML) data processing, it is widely used in research of solid waste (SW). This study analyzed the research and developmental progress of the applications of ML in the life cycle of SW. Statistical analyses were undertaken on the literature published between 1985 and 2021 in the Science Citation Index Expanded and Social Sciences Citation Index to provide an overview of the progress. Based on the articles considered, a rapid upward trend from 1985 to 2021 was found and international cooperatives were found to have strengthened. The three topics of ML, namely, SW categories, ML algorithms, and specific applications, as applied to the life cycle of SW were discussed. ML has been applied during the entire SW process, thereby affecting its life cycle. ML was used to predict the generation and characteristics of SW, optimize its collection and transportation, and model the processing of its energy utilization. Finally, the current challenges of applying ML to SW and future perspectives were discussed. The goal is to achieve high economic and environmental benefits and carbon reduction during the life cycle of SW. ML plays an important role in the modernization and intellectualization of SW management. It is hoped that this work would be helpful to provide a constructive overview towards the state-of-the-art development of SW disposal.     

Repercussions of COVID-19 pandemic on solid waste generation and management strategies

• Implication of COVID-19 on medical waste and MSW generation is studied. • Challenges and effective strategy of solid waste generation is reviewed. • 2.9 million tons of COVID-19 related medical waste has been generated until Sep. 22. • The pandemic has postponed policies related to the reduction of plastic use. • Blockade resulted in a significant drop in waste generation in some regions. It has been over ten months since the beginning of the 2019 coronavirus disease (COVID-2019), and its impact on solid waste management, especially medical waste, is becoming clearer. This study systematically reviews the potential influences of the COVID-19 pandemic on medical waste, personal protection equipment waste and municipal solid waste (MSW), and discusses the corresponding measures and policies of solid waste management in typical countries. The results show that the generation of medical waste from the pandemic increased significantly, with 18%‒425% growth. It is estimated that the daily output of COVID-19 medical waste increased from 200 t/d on Feb. 22 to over 29000 t/d at the end of September 2020 throughout the world. The use of personal protective equipment will continue to grow in the long-term, while the blockade and isolation measures greatly reduced the volume of commercial waste, especially for tourist cities, and part of this waste was transferred to household waste. Residents’ attitudes and behavior toward food waste have changed due to the COVID-19 pandemic. In response to the pandemic, international organizations and several countries have issued new policies and guidelines and adjusted their management strategies for medical waste and MSW treatment. The pandemic has brought specific challenges to the disposal capacity of medical waste worldwide. It has also brought about the stagnation of policies related to the reduction of plastic products and waste recycling. This study will provide some useful information for managers and governmental officials on effective solid waste management during and after the COVID-19 pandemic.     

Assessment of key parameters in municipal solid waste management: a prerequisite for sustainability

Municipal solid waste management was studied for 1 year in a representative urban area of Lahore city for environmental sustainability. The effects of financial status of the household and the seasonal variations on generation rate and compositions of municipal solid waste (MSW) were determined. MSW generation rate and the economic status of the households were positively correlated (p < 0.05). Seasonal variations observed were significant only for organics (p = 0.001), plastics (p = 0.008) and food waste fractions (p = 0.009) in MSW. Response surface regression model developed and analysed by Minitab-15® showed that the interaction of season and different economic zones of the town on the MSW generation rate was non-significant (p = 0.334). Elemental and heating value analyses of the mixed organic fractions in kitchen waste had carbon 47.93%, hydrogen 6.20%, nitrogen 2.24%, sulphur 0.23%, oxygen 39.01%, and C and N ratio 27.78. Findings concluded that food waste was 56% of total MSW with 71.03% moisture content and a modest heating value of 5566 J/g. Existing temporary storage capacity of MSW is 51% of the total MSW generated considering the weighted MSW generation rate of 0.57 kg/person/day calculated in this study. Composting could be a possible final disposal option due to high moisture and organic content and can be studied in future research. Development of a transfer station, introduction of home composting programmes and awareness towards proper segregation and reduction of waste at the household level is suggested to attain sustainability in the MSW management system.     

Development and prospects of municipal solid waste (MSW) incineration in China

With the lack of space for new landfills, municipal solid waste (MSW) incineration is playing an increasingly important role in municipal solid waste management in China. The literatures on certain aspects of incineration plants in China are reviewed in this paper, including the development and status of the application of MSW incineration technologies, the treatment of leachate from stored MSW, air pollution control technologies, and the status of the fly-ash control method. Energy policy and its promotion of MSW-to-energy conversion are also elucidated.     

An interval joint-probabilistic programming method for solid waste management: a case study for the city of Tianjin, China

Currently, environmental protection and resources conservation continue to be challenges faced by solid-waste managers in China. These challenges are being further compounded by rapid socioeconomic devel- opment and population growth associated with increased waste generation rates and decreased waste disposal capacities. In response to these challenges, an interval joint-probabilistic mixed-integer programming （IJMP） method is developed for supporting long-term planning of waste management activities in the city of Tianjin, which is one of the largest municipalities in the northern part of China. In the IJMP, joint probabilistic constraints are introduced into an interval-parameter mixed-integer programming framework, such that uncertainties presented in terms of interval values and random variables can be reflected. Moreover, a number of violation levels for the waste-management-capacity constraints are examined, which can facilitate in-depth analyses of tradeoffs among economic objective and system-failure risk. The results indicate that reasonable solutions have been generated. They are valuable for supporting the adjustment of the city＇s existing waste-management practices and the long- term planning of the city＇s waste-management facilities.     

A steam dried municipal solid waste gasification and melting process

Considering high-moisture municipal solid waste (MSW) of China, a steam dried MSW gasification and melting process was proposed, the feasibility was tested, and the mass and energy balance was analyzed. Preliminary experiments were conducted using a fixed-bed drying apparatus, a 200 kg per day fluidized-bed gasifier, and a swirl melting furnace. Moisture percentage was reduced from 50% to 20% roughly when MSW was dried by slightly superheated steam of 150°C?C350°C within 40 min. When the temperature was less than 250°C, no incondensable gas was produced during the drying process. The gasifier ran at 550°C?C700°Cwith an air equivalence ratio (ER) of 0.2?C0.4. The temperature of the swirl melting furnace reached about 1240°C when the gasification ER was 0.3 and the total ER was 1.1. At these conditions, the fly ash concentration in the flue gas was 1.7 g·(Nm³)^?1, which meant over 95% fly ash was trapped in the furnace and discharged as slag. 85% of Ni and Cr were bound in the slag, as well as 60% of Cu. The mass and energy balance analysis indicates that the boiler heat efficiency of an industrial MSW incineration plant reaches 86.97% when MSW is dried by steam of 200°C. The boiler heat efficiency is sensitive to three important parameters, including the temperature of preheated MSW, the moisture percentage of dried MS Wand the fly ash percentage in the total ash.     

有机固体废弃物在持续农业中的资源化利用

有机固体废弃物产生量巨大且成分复杂,其对环境的污染已越来越多地引起人们的关注.它含有大量营养成分和有机质,在农业生产上除可以满足作物生长对养分的需要外,其丰富的有机质含量还可以改善土壤的物理化学性状,培肥土壤,有利于农业的可持续发展.有机固体废弃物的农业资源化处理利用是最积极有效的措施之一.     

Ecofriendly approach of urban solid waste management: a case study of Jalgaon city, Maharashtra

In India, the traditional methods are used for urban solid waste management. These practices are associated with degradation of the urban environment Hence, an environmentally sound garbage management system is required for the urban waste management. The concept of waste minimization needs to be adopted in such systems. It is possible to implement certain corrective measures at collection, storage, transport and disposal of urban solid waste to minimize the adverse impacts on the environment The present investigations are emphasized on generation, characterzation and ecofriendly disposal of solid waste generated in Jalgaon city, Maharashtra. In the present study the waste generation at source was studied in the various income groups of the city. The per capita waste generation was studied by sampling the waste directly from the source of generation. The study reveals that the waste generation is large in the high-income group followed by middle and low-income group public. Further the physicochemical characterization of the waste was also studied. The data generated will help to develop environmentally sound and economically feasible solid waste management system for Ihe city.     

Assessment of pollution of potentially harmful elements in soils surrounding a municipal solid waste incinerator,China

We assessed the contamination levels of Mn, Zn, Cr, Cu, Ni, Pb, As and Hg and the risks posed by these potentially harmful elements in top-soils around a municipal solid waste incinerator (MSWI).We collected 20 soil samples, with an average pH of 8.1, and another fly ash sample emitted from the MSWI to investigate the concentrations of these elements in soils. We determined the concentrations of these elements by inductively coupled plasma–optical emission spectrometer (ICP-OES), except for Hg, which we measured by AF-610B atomic fluorescence spectrometer (AFS). We assessed the risks of these elements through the use of geoaccumulation index (I _geo), potential ecological risk index (RI), hazard quotient (HQ _i ) and cancer risk (Risk _i ). The results showed that concentrations of potentially harmful elements in soil were influenced by the wind direction, and the concentrations of most elements were higher in the area northwest of the MSWI, compared with the area southeast of the incinerator, with the exception of As; these results were in accordance with those results acquired from our contour maps. According to the I _geo values, some soil samples were clearly polluted by Hg emissions. However, the health risk assessment indicated that the concentrations of Hg and other elements in soil did not pose non-carcinogenic risks to the local populations. This was also the case for the carcinogenic risks posed by As, Cr, and Ni. The carcinogenic risk posed by As was higher, in the range 6.49 × 10^–6–9.58 × 10^–6, but this was still considered to be an acceptable level of risk.

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垃圾填埋场渗滤液回流处理技术研究进展

垃圾渗滤液回流处理后，CODcr去除率最高达95％，在半好氧状态下NH3-N质量浓度降低至10mg/L几以下，渗滤液水质得到改善；渗滤液回流增加了湿度，使有机物的降解速率加快；渗滤液同流处产甲烷速率是不回流处产甲烷速率的2倍多：渗滤液回流处的总沉降幅度可达填埋场深度的20％，而不回流处仅为8％。回流处理技术分为直接回流至垃圾层、表面喷灌或浇灌至填埋场表面、地表下回流或内层回流技术。在填埋场处于产酸阶段早期，回流的渗滤液量宜少不宜多：在产气阶段则可逐渐增加。应将稳定化程度高的垃圾层区(产甲烷区)排出的渗滤液回流至新填人的垃圾层(产酸区)，将新垃圾层所产生的渗滤液回流至老的稳定化区。通过控制垃圾的组成、回流的时间、渗滤液的pH值等手段可改善回流处理效果。     

Performance evaluation of circulating fluidized bed incineration of municipal solid waste by multivariate outlier detection in China

This first nationwide survey was conducted to evaluate the overall performance of the circulating fluidized bed (CFB) incineration of municipal solid waste (MSW) in 2014-2015 in China. Total 23 CFB incineration power plants were evaluated. The data for monthly average flue gas emission of particles, CO, NO _x , SO₂ and HCl were collected over 12 consecutive months. The data were analyzed to assess the overall performance of CFB incineration by applying the Mahalanobis distance as a multivariate outlier detection method. Although the flue gas emission parameters had met the Chinese national emission standards, there were 11 total outliers (abnormal behavior) detected in 6 out of 23 CFB incineration power plants from the perspective of the MSWincineration performance. The results demonstrate that it is more important for a better performance of CFBs to reduce the frequencies of the MSW load changes, rather than the magnitudes of the MSW load changes, particularly reducing the frequencies in the range of 10% and more of the load changes, under the same and stable conditions. Furthermore, the overloading occurs more often than the underloading during the operation of the CFB incineration power plants in China. The frequent overloading is 0% to 30% of the designed capacity. To achieve the stable performance of CFBs in practice, an appropriately designed MSW storage capacity is suggested to build in a plant to buffer and reduce the frequency of the load changes.

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A strategy for wildlife management in depopulating rural areas of Japan

Former ranges of wild animals have been reestablished in many developed countries. However, this reestablishment has led to increasing human–wildlife conflict in agroforest ecosystems. In Japan, human–wildlife conflict, such as crop raiding by and ecological impacts of wild ungulates and primates, is a serious problem in depopulated rural areas due to these animal range expansions and increased abundances. Japan's human population is predicted to decline by 24% by 2050, and approximately 20% of agricultural settlements will become completely depopulated. In this scenario, anthropogenic pressures on wildlife (e.g., hunting and habitat alteration) will continue to decrease and human–wildlife conflict will increase due to increasing wildlife recovery. Japan's local governments plan to slow range recovery, prevent species reestablishment, or remove recolonizing large mammals through lethal control. This strategy, however, is not cost-effective, and workforce shortages in depopulated communities make it infeasible. Moreover, the suppression of wildlife prevents the recovery of ecological functions and thus would degrade regional biodiversity. The declining pressure on wildlife that accompanies human depopulation will prevent the restoration of any past states of human–wildlife interaction. We suggest human-used areas in rural landscapes be aggregated in compact cities and that in transition zones between human settlements and depopulated lands that land-sharing approaches be applied. Concentrating management efforts in compact cities may effectively decrease human–wildlife conflict, rather than intensifying human pressures. Reforestation of depopulated lands may lead to recovery of wildlife habitats, their ecosystem functions, and regional biodiversity due to minimization of negative anthropogenic effects (land-sparing approach). Balancing resolution of human–wildlife conflict and ecological rewilding could become a new, challenging task for regional wildlife managers.     

塑料废弃物污染的综合治理研究进展

近年来,随着经济的发展,废旧塑料大幅增加,塑料废弃物所造成污染已经成为了破坏环境的主要因素之一.塑料废弃物污染即所谓的白色污染,主要是由废旧塑料高分子的不可降解性和添加剂的毒害性引起的.文章在对白色污染产生的背景及其污染危害的基础上,讨论了治理白色污染的治理的两个方面,一方面对可降解塑料和对废旧塑料的回收再生两个主要的技术研究开发方向进行了综述和展望,详细介绍了光降解塑料、光-生物双降解塑料和生物降解塑料的研发进展,并对填埋、焚烧和再生三种塑料废弃物的处理方法进行了详细的分析;另一方面就立足循环经济理论,加强政策法规的运用,同时加强宣传教育等方面的问题进行了讨论,并提出了相应的对策.     

Removal of odors and VOCs in municipal solid waste comprehensive treatment plants using a novel three-stage integrated biofilter: Performance and bioaerosol emissions

• TSIBF was composed of ABRS, FRS and HBRS. • THIBF can effectively remove various odors, VOCs and bioaerosols. • Different reaction segments in TSIBF can remove different types of odors and VOCs. • TSIBF can reduce the emission of bioaerosols through enhanced interception. A novel three-stage integrated biofilter (TSIBF) composed of acidophilic bacteria reaction segment (ABRS), fungal reaction segment (FRS) and heterotrophic bacteria reaction segment (HBRS) was constructed for the treatment of odors and volatile organic compounds (VOCs)from municipal solid waste (MSW) comprehensive treatment plants. The performance, counts of predominant microorganisms, and bioaerosol emissions of a full-scale TSIBF system were studied. High and stable removal efficiencies of hydrogen sulfide, ammonia and VOCs could be achieved with the TSIBF system, and the emissions of culturable heterotrophic bacteria, fungi and acidophilic sulfur bacteria were relatively low. The removal efficiencies of different odors and VOCs, emissions of culturable microorganisms, and types of predominant microorganisms were different in the ABRS, FRS and HBRS due to the differences in reaction conditions and mass transfer in each segment. The emissions of bioaerosols from the TSIBF depended on the capture of microorganisms and their volatilization from the packing. The rational segmentation, filling of high-density packings and the accumulation of the predominant functional microorganisms in each segment enhanced the capture effect of the bioaerosols, thus reducing the emissions of microorganisms from the bioreactor.     

Preliminary techno-economic analysis of three typical decentralized composting technologies treating rural kitchen waste: a case study in China

● Decentralized composting (DC) is a profitable KW treating technology. ● SAC and BEC were economically attractive in rural area, while HDC was unprofitable. ● KW handling subsidy plays a vital role in making DC profitable. ● SAC and BEC have great potential in promoting rural KW treatment. This study was designed to evaluate whether the decentralized rural kitchen waste (KW) composting technologies used in China can be widely applied. To this end, we completed a techno-economic analysis of three typical types of KW compositing, namely solar-assisted (SAC), bio-enhanced (BEC), and heat-dewatering composting (HDC). These evaluations revealed that all three technologies produce composting products that meet China’s organic fertilizer standard and that both SAC and BEC are economically self-sustaining and generate net profits (18824.94 and 17791.52 US$/a) and positive net present values (32133.11 and 25035.93 US$). Subsequent sensitivity analysis demonstrated that the KW-handling subsidy plays a critical role in making decentralized composting economically attractive. Based on these analyses, we believe that reducing the coverage area of SAC, reducing the operating cost of BEC and HDC, upgrading composting products, and strengthening secondary pollution control would aid in supporting the technological improvement of these processes. Moreover, providing appropriate subsidies and promulgating specific standards and policies for KW fertilizer are key strategies for decentralized rural KW composting management.