Solid Waste In China Research Articles

Research progress on high-value utilization technology of sludge solid waste in China

Research progress on high-value utilization technology of sludge solid waste in China

Experimental study on the utilization of Fly ash solid waste in tunnel shotcrete materials

AbstractFly ash has emerged as a prominent solid waste in China, leading to various environmental concerns and posing a threat to the health of living organisms, including humans. To enhance the industrial applicability of this waste material, a novel approach has been proposed wherein sand is replaced with fly ash as the primary raw material for wall grouting of coal mine roadways. To address the issue of low compressive strength and to improve the properties of fly ash shotcrete materials, a method employing an alkali activator to stimulate the chemical activity of fly ash has been put forward. The long‐term effectiveness of the shotcrete material has been evaluated using compressive strength testing and scanning electron microscopy testing methods. The impact of replacing sand with fly ash on the compressive strength of shotcrete and the activation effect of sodium sulfate (Na2SO4), NaOH, and Na2SiO3 on fly ash shotcrete have been studied. The results indicate that the compressive strength of fly ash shotcrete shows optimal improvement when the content of Na2SO4 is 3%. The ideal ratio of cement to fly ash is 1:3. Therefore, incorporating an appropriate amount of alkaline activator could effectively address the compressive strength issues of fly ash shotcrete materials.

Oil-based drilling cutting pyrolysis residues- phosphogypsum foamed ceramics: Basic properties, microsintering mechanism and heavy metals solidification

Oil-based drilling cutting pyrolysis residues(ODPR) and phosphogypsum(PG) are typical types of industrial solid waste in China, characterized by low utilization rate and high output. The large amount of untreated accumulation will release heavy metals(HMs) and other pollutants, posing risks to the environment. Therefore, there is an urgent need to develop a high value-added building material product that can reduce environmental hazards while improving utilization rate. Based on this background, this study uses ODPR and PG as raw materials to explore their potential applications in the field of foamed ceramics. Research has shown that different sintering processes have a significant impact on the appearance and performance of products. By adjusting the preparation process, foamed ceramic products with excellent performance can be prepared. When the sintering temperature is 925℃, the foaming agent dosage is 3 %, and the raw material ratio ODPR:PG:Borax=35:45:20, a foamed ceramic product with a porosity of 60.95 %, water absorption rate of 3.4 %, compressive strength of 4.8 MPa, thermal conductivity of 0.8016 W/(m·k), and acid and alkali resistance of 98.57 % and 99.44 % can be prepared. The product meets the relevant requirements of “Fired heat preservation brick and block (GB/T 26538)” and “ General Specification for porous ceramic products (GB/T 16533)”. The HMs content test showed that the Ni and Pb contents in the pre-sintered blanks were the highest, at 0.6308 mg/kg and 0.3182 mg/kg, respectively. However, after high-temperature calcination, the solidification rate of HMs could reach up to 98.93 %, and the leaching amount was significantly reduced. The three further evaluation methods indicate that HMs in the pre-sintered blanks and foamed ceramic products do not pose significant ecological risks. The research results provide a green inorganic insulation material in the field of solid waste control and building materials.

Construction of a New Emergency Management System for Potentially Viral/Viral Municipal Solid Waste in China: Based on the "Beam-Column Structure" Framework Model

Emergency management of municipal solid waste during public health emergencies is crucial for curbing the spread of viruses and controlling environmental pollution. Most existing solid waste management systems, are designed with a top-down approach, covering multiple industries and sectors. However, these systems often fail to effectively manage potentially viral solid waste in household waste, which impedes effective solid waste management during public health emergencies and increases the risk of viral outbreaks. For example, during the COVID-19 outbreak, negligent management of potentially viral solid waste may result in the formation of a potential transmission chain of COVID-19 virus. Improper waste management may contaminate natural vectors such as water, soil and air, thereby increasing the pathways of human contact with infected vectors and promoting the risk of transmission of viral diseases such as dengue, Zika and hepatitis A. In this study, the applicability and limitations of the Chinese public emergency management system in the disposal of Potentially Viral/Viral Municipal Solid Waste (PVMSW) were analyzed in the breakout of public health crises. To address the need for precise risk control, efficient collaboration among key stakeholders, functional integration crossing multiple management organizations and flexible responses to complex situations, we proposed a PVMSW emergency management system based on a "Beam-Column Structure" model. This system consists of four modules: main traction, organizational leadership, functional articulation and demand matching. Each module is supported by the corresponding safeguards, including multi-level subject responsibilities, multi-scenario organization and implementation, multi-chain process connection and multi-demand control methods. The PVMSW emergency management system proposed in this study contributes to extending the framework of existing waste management protocols and enhancing the timely collection, transportation and disposal of PVMSW in public health crises. It offers valuable insights and guidance on the practices for improving risk awareness and management capacity in China's solid waste emergency response.

Investigation of the activator system for coal gangue and its optimal utilization in composite cementitious materials

The extensive accumulation of coal-derived solid wastes in China has become a significant environmental challenge. Utilizing these wastes as resources is considered an effective approach. This study investigated activation systems for coal gangue to determine the optimal dosage for incorporation into cementitious materials. The effects of types and dosages of admixtures on the mechanical properties were examined. The results showed that augmenting the coal gangue content within a certain range enhanced the compressive strength of the composite cementitious materials. However, exceeding 20 wt.% led to a decline in compressive strength. The addition of coal gangue led to an increase in porosity. Furthermore, the addition of 4% lime and 4% gypsum resulted in enhanced properties. The performance of the resultant optimal cementitious material surpasses that of P·O 32.5 cement, making it a viable replacement in construction sector and contributing to the realization of resource recycling and ecological civilization construction goals.

Research on the impact mechanism of changes in the production of medical solid waste in China before and after COVID-19.

The changes of medical solid waste (MSW) output in recent years have had a significant impact on the spread of the virus. There is a high-risk transmission of MSW in various stages such as storage, transportation, and treatment during the COVID-19. To cope with the risks brought by the epidemic, normalized prevention consumes a large amount of protective clothing, medical masks, goggles, packaging bags, and other related medical supplies. There is a significant uncertainty in the amount of MSW output that poses a risk of COVID-19 infection in the event of an emergency, which increases the difficulty of collecting and handling epidemic prevention MSW. The analysis of MSW data from 2000 to 2022 found a stable growth trend before 2019. However, the MSW data was a sudden increase trend from 2020 to 2022, and the COVID-19 in China was characterized by an initial stage, an outbreak stage, and a stable growth stage. The range of MSW output during the epidemic was (1.19-1.75) × 106 t a-1. The amount of MSW was approximately 1.19 × 106 t a-1 during the normalized epidemic period, and its treatment cost was as high as 3.57 × 109 yuan (RMB)·a-1. The distribution of MSW output was uneven due to factors such as climate conditions, population data, and local economy. This study has important reference value for epidemic medical material reserves and MSW treatment.

Effect of long-term dry-wet circulations on the Solidification/stabilization of Municipal solid waste incineration fly ash using a novel cementitious material.

Solidification/stabilization (S/S) is a typical technique to immobilize toxic heavy metals in Municipal solid waste incineration fly ash (MSWI FA). This study utilized blast furnace slag, steel slag, desulfurization gypsum, and phosphoric acid sludge to develop a novel metallurgical slag based cementing material (MSCM). Its S/S effects of MSWI FA and long-term S/S effectiveness under dry-wet circulations (DWC) were evaluated and compared with ordinary Portland cement (OPC). The MSCM-FA block with 25 wt.% MSCM content achieved 28-day compressive strength of 9.38MPa, indicating its high hydration reactivity. The leaching concentrations of Pb, Zn and Cd were just 51.4, 1895.8 and 36.1 μg/L, respectively, well below the limit standard of Municipal solid wastes in China (GB 16889-2008). After 30 times' DWC, leaching concentrations of Pb, Zn and Cd for MSCM-FA blocks increased up to 130.7, 9107.4 and 156.8 μg/L, respectively, but considerably lower than those for OPC-FA blocks (689, 11,870.6 and 185.2 μg/L, respectively). The XRD and chemical speciation analysis revealed the desorption of Pb, Zn and Cd attached to surface of C-S-H crystalline structure during the DWC. The XPS and SEM-EDS analysis confirmed the formation of Pb-O-Si and Zn-O-Si bonds via isomorphous replacement of C-A-S-H in binder-FA blocks. Ettringite crystalline structure in OPC-FA block was severely destructed during the DWC, resulting in the reduced contents of PbSO4 and CaZn2Si2O7·H2O and the higher leachability of Pb2+ and Zn2+.

Factors influencing residents’ waste management behavior: A case study in Beijing, China

With the continuous increase of the total amount of municipal solid waste in China, waste management has become an urgent matter. To address this challenge, the Chinese government recently launched a new waste management system. Previous studies have confirmed the effectiveness of incorporating intrinsic motivation factor into the theory of planned behavior for predicting green behavior, however, the interaction between variables in the model has not been fully explored in the Chinese context. Therefore, this study extended the theory of planned behavior with moral norms to evaluate the household waste management behavior of Beijing residents. With 342 residents as samples, hierarchical multiple regression was used for analysis. The empirical result showed that all determinants in the extended model positively predict behaviors. Moral norms were the most important determinants of behavior, followed by subjective norms, and then perceived behavioral control and attitude. In addition, moral norms played a mediating role in the influence of attitudes and subjective norms on behavior. These findings will help expand and improve understanding of the key factors affecting residential waste management, make reasonable recommendations for environmental protection and sustainable development.

Present situation of comprehensive utilization of coal-based solid waste

At present, the annual discharge of coal-based solid waste in China has exceeded 800 million tons, but the mainstream treatment methods are still simple treatment methods such as goaf backfilling and openpit stacking. The massive stacking of coal-based solid waste is not only a serious waste of resources itself, but also brings a series of problems such as environmental pollution. Under the “Carbon Peak” and “Carbon Neutrality” strategy in China, in order to achieve green and rapid development of the coal industry, it is necessary to solve the problem of coal-based solid waste treatment and achieve green and comprehensive utilization of coal-based solid waste. Taking coal gangue, gasification slag and fly ash as representative coal-based solid waste, the present situation of coal-based solid waste production in China and the basic properties of coal-based solid waste are introduced. The utilization status and application characteristics of coal-based solid waste in cement concrete, roadbed materials, soil improvement and so on are focused on, and the resource utilization potential of coal-based solid waste is analyzed and summarized. Then the application prospect of coal-based solid waste in high-value utilization in the future is analyzed and prospected.

Construction of Testing Standards System for Comprehensive Utilization of Bulk Industrial Solid Waste

According to the general steps of comprehensive utilization of each type of bulk industrial solid waste, including fly ash, coal gangue, tailings, smelting slag, industrial by-product gypsum, and red mud, we construct the testing standards system for comprehensive utilization of bulk industrial solid waste in China. The standards system, according to the lifecycle stage of "raw materials - pre-treatment - processing - forming products - using products", can be divided into 5 standard subsystems, namely a subsystem of physical property testing standards for raw materials, a subsystem of chemical property testing standards, a subsystem of process testing standards, a subsystem of the product quality performance testing standards and a subsystem of the environmental impact testing standards. The standards system provide top-level guidance for the implementation and development of comprehensive utilization testing methods for bulk industrial solid waste.

Process design and optimization on self-sustaining pyrolysis and carbonization of ultra-low calorific value coal gangue

In the process of coal mining, washing and utilization, a huge amount of coal gangue (CG) is produced, which has become the largest solid waste in China. Large accumulation of CG is not only occupying the land area, but also leading to severe environment pollution. Therefore, the disposal of CG is extremely urgent in China. In this paper, a novelty process of CG pyrolysis is proposed, which can achieve self-sustaining treatment of CG. Based on the analysis results of pyrolysis experiments, the process simulation is established by Aspen plus software. By comparing the effects of CG type and pyrolysis temperature on the system, the stability and flexibility of the system is analyzed. The experiments results show that, with the increase of pyrolysis temperature, the oil and gases yields of CG pyrolysis increases. The simulation results show that under the same process conditions, the economy of the system strongly depends on the quality of CG, and the method proposed in this paper is more economical to treat ultra-low calorific value CG. The pyrolysis temperature also significantly affects the energy self-balance of the system, and the recommended pyrolysis temperature is about 600 ℃ for industry process.

What establishes citizens' household intention and behavior regarding municipal solid waste separation? A case study in Jiangsu province

Management of municipal solid waste in China requires special attention because China has become the world's largest producer of municipal solid waste, and the overall volume of municipal solid waste produced is still increasing. Recently, local and central Chinese authorities have significantly enhanced municipal solid waste treatment. Therefore, this current study aims to extend the theory of interpersonal behavior with perceived benefits to assess citizens' household municipal solid waste separation intention and behavior in Jiangsu province. This study will help widen and improve the comprehension of the key factors affecting citizens' household municipal solid waste separation. Utilizing data from 615 sampled citizens in Jiangsu, analysis was conducted using partial least squares structural equation modeling. Empirical evidence revealed that affect, attitude, and social factors positively influence citizens' household municipal solid waste separation intentions. Perceived benefits also positively impact citizens' household municipal solid waste separation intentions via attitude. Facilitating conditions influence citizens' household municipal solid waste separation intentions and behaviors. The study also found that facilitating conditions negatively moderated the association between intention and behavior in Jiangsu Province. Habits significantly and positively influenced and moderated citizens' household municipal solid waste separation intentions and behaviors. These findings provide great insights and contributions to pro-environmental research and can be applied to various provinces that value household municipal solid waste separation in China.

Microbial diversity and potential health risks of household municipal solid waste in China: A case study in winter during outbreak of COVID-19

Microbial (bacteria and fungi) community structures and their distributions in urban household municipal solid waste (HMSW) were characterized in a sampling campaign in 38 cities of China covering 5 climatic zones. All samples were collected from garbage containers in residential communities during the Winter of 2022, from January 11 to 26. A total of 247 bacterial genera belonging to 22 phyla were identified among the samples. Firmicutes (44.3 %), Bacteroidetes (33.77 %) and Proteobacteria (21.54 %) were the top 3 dominant phyla, and Arcicella (33.11 %) and Leuconostoc (21.87 %) were the dominant genera. Meanwhile, 124 fungal genera from 7 fungal phyla were detected. Ascomycota was the most dominant phylum, with an average relative abundance of 77.31 %. Hanseniaspora (24.03 %), Debaryomyces (13.47 %), Candida (12.18) were the top 3 dominant fungal genera. Alpha-diversity analysis showed that the species richness and diversity of bacterial and fungal communities of HMSW samples belonging to different climatic zones did not differ significantly. Nonmetric multidimensional scaling (NMDS) analysis confirmed that climatic had an effect on microbial communities but did not show a significant correlation. In addition, the distribution of microbial community in different samples from the same climate zone varied considerably, suggesting the HMSW source play important role in shaping microbial community composition. Considering that residential HMSW is relatively fresh, we speculates that the original microorganisms residing in different components of HMSW are key influencing factor for the community, while the reshaping force driven by environmental conditions are relatively weak. In addition, the study identified 13 bacterial and 16 fungal pathogens with Pseudomonas putida (0.25 %) and Sclerotinia sclerotiorum (2.12 %) as the most abundant potential pathogenic bacteria and fungi, respectively. These findings provide valuable information for characterizing microbial features and potential risks of HMSW in its management system.

Metagenomics insights into the effect of co-landfill of incineration fly ash and refuse for bacterial community succession and metabolism pathway of VFAs production

With the development of incineration technologies, incineration has become the most common treatment method of municipal solid waste in China. However, stabilized fly ash may enter landfills during the transition from landfill to incineration, which caused uncertain impact on landfill waste stabilization. Two simulated co-landfill columns were constructed based on different co-landfill methods (layer co-landfill and mixed co-landfill) to investigate the effect of stabilized fly ash co-landfilled municipal solid waste for bacterial community succession and change in metabolic pathways during hydrolysis-acidogenesis stage. The mixed co-landfill method resulted in higher degree of organic matter degradation, and the concentrations of volatile fatty acids (VFA) and chemical oxygen demand (COD) in leachate were higher. The dominant phyla were Firmicutes in the layered co-landfill column and Bacteroidetes in mixed co-landfill column. The dominant genera for the total bacterial composition and VFA production were different, Pseudomonas and Propionibacterium, Proteiniphilum and unclassified Bacteroides were the dominant genera responsible for VFA generation in the layered and mixed co-landfill columns. The genes for butyrate production were enriched in the layered co-landfill column, whereas those related to acetate production were enriched in mixed co-landfill column. However, the layered co-landfill inhibited the microbial metabolic activity at the end of the co-landfill process.

Effects of fuel-staged gasification on mechanism of steam gasification of coal gangue and corn straw

Coal gangue (CG) and corn straw (CS) are regarded as the bulk of solid wastes in China due to their high annual yield, inefficient utilization, and low added value. In this work, the comparison experiments between fuel-staged gasification and conventional co-gasification for CG and CS were conducted in a new type of three-way reactor. The effects of volatiles and AAEMs in CS on fuel-staged gasification were analyzed by investigating CS ratio in the primary bed. And the influence of diffusion resistance was studied by adjusting CG ratio in the secondary bed. The results showed that the thermal interactions of CG and CS in primary bed were considered as the oxidation of C–C and CC structures of CG by C–O–C and C–OH bonds of CS to form CO. Meanwhile, the breaking of O–CO and lactone groups could generate a significant amount of CO2 to accelerate the Boudouard reaction of primary char. In addition, calcium minerals in CS could combine with CG minerals into anorthite, which would promote the transverse fracture and longitudinal stacking of primary residue char. Besides, steam reforming of volatiles/tar and ring-opening reactions of residue char were both controlled by the diffusion resistance derived from secondary CG. The conclusions would provide some theoretical bases and engineering foundations for the industrial applications of fuel-staged gasification, such as the design of fuel-staged gasifier and the selection of two-staged fuel.

The temporal and spatial characteristics and influencing factors of CO2 emissions from municipal solid waste in China

Understanding the temporal and spatial characteristics of carbon dioxide (CO2) emissions from municipal solid waste (MSW) and a quantitative evaluation of the contribution rate of the factors influencing the changes in CO2 emissions are important for pollution and emission reduction and the realization of the "double carbon" goal. This study analyzed the spatial and temporal evolution of waste generation and treatment based on panel data from 31 Chinese provinces over the past 15years and then applied the logarithmic mean Divisia index (LMDI) model to study the driving factors of CO2 emissions from MSW. China's MSW production and CO2 emissions displayed a rising trend, and the overall CO2 emissions showed a geographical pattern of being high in the east and low in the west. Carbon emission intensity, economic output, urbanization level, and population size were positive factors that increased CO2 emissions. The most important factors driving CO2 emissions were carbon emission intensity and economic output, with cumulative contribution rates of 55.29% and 47.91%, respectively. Solid waste emission intensity was a negative factor in reducing CO2 emissions, with a cumulative contribution rate of -24.52%. These results have important implications for the design of policies to reduce CO2 emissions from MSW.

Evaluation of Biomass Solid Waste as Raw Material for Preparation of Asphalt Mixture

At present, the resource utilization of solid waste in China is facing prominent problems such as high production intensity, insufficient utilization, and low added value of products. The preparation of biomass composites from biomass solid waste and plastic solid waste reduces not only environmental pollution and energy consumption but also promotes the high-value utilization of solid waste. So, the characterization and preparation experiments of samples with two different biomass are carried out. The wheat straw fiber and corn straw fiber were added into the bio-asphalt mixture with the content of 0.1%, 0.2%, 0.3%, and 0.4%, respectively, with the content of 9% and 12% bio-heavy oil. The physical properties and rheological properties of asphalt were analyzed and evaluated by three indexes and a dynamic shear rheological test. Through the rutting test and immersion Marshall test, high-temperature performance and biological asphalt mixture’s water stability were evaluated. The results show that straw fiber can improve bio-asphalt mixture’s road performance, especially the performance of high-temperature rutting. When the fiber content of bio-asphalt with 9% bio-heavy oil content is 0.3%, the physical properties and rheological properties of bio-asphalt are the best. Corn straw fiber’s influence on bio-asphalt mixture was better than that of wheat straw fiber.

Changes and Future Issues in Policies for the Classification of Municipal Solid Waste in China

Changes and Future Issues in Policies for the Classification of Municipal Solid Waste in China

Energy recovery from solid wastes in China and a Green-BRI mechanism for advancing sustainable waste management of the global South

Energy recovery from solid wastes in China and a Green-BRI mechanism for advancing sustainable waste management of the global South

Quantitative analysis of CO2 uptake by alkaline solid wastes in China

About two-thirds of global CO2 emissions from the energy and industry sectors are generated in China, accounting for approximately 30% of total global CO2 emissions. These carbon-intensive processes usually produce a large amount of so-called alkaline solid wastes e.g. blast furnace slag (BFS), which have shown great potential to serve as CO2 absorbers. In this regard, the climate impacts of these human activities should be re-evaluated by considering the carbon offsetting effects. While recent studies have been focusing on accelerated carbonation of such ‘waste’ from a technical perspective, the natural carbonation of these solid residues has not been comprehensively investigated. In this research, combining experimental data, we established an analytical carbon sink accounting model to estimate the CO2 uptake of 7 types of alkaline solid wastes produced in China between 1930 and 2020 using material flow analysis (MFA), life-cycle assessment (LCA), and Monte Carlo methods. The results show that China's alkaline solid wastes from the identified industrial and agroforestry processes in 2020 absorbed 64.27 Mt CO2 (35.91–111.01, 95% CI), offsetting 2.2% of the CO2 emissions from Chinese industrial production. Cumulatively, 1099.51 Mt CO2 had been sequestered by natural carbonation, since 1930. The majority of CO2 uptake is attributed to coal combustion ash (CCA) and biomass ash (BA), which accounted for 35.9% and 26.3% of the total uptake combined respectively. All types of solid wastes exhibited rapidly increasing sequestration from 1930 to 2020 apart from yellow phosphorous slag (YPS) and oil shale ash (OSA), with substantial interannual variability. Our results indicate that the natural carbonation of such ‘waste’ can reduce the carbon footprint of the corresponding industrial and agroforestry processes, and make the case for further research of their full potential.