Solid Waste Recycling Research Articles

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.

Recycling of ferronickel slag tailing in cementitious materials: Activation and performance

As an industrial by-product containing pozzolanic components, recycled ferronickel slag (FNS) has the potential to be supplementary cementitious materials (SCMs) to reduce the massive carbon footprint of the cement industry, however, the main limitation of ferronickel slag as SCMs is the low hydration rate at an early age. In this study, the pozzolanic activity property results indicate that if the proportion is more than 10 %, FSN can hardly participate in the cement hydration reaction during the early stage, even the mechanical strength of FNS-mortar decreases obviously with the higher proportion of ferronickel slag. Therefore, mechanical grinding and steam curing at an early age are applied to promote the reaction activity of the recycled ferronickel slag tailing in this study. Compared with standard curing, the compressive strength of hardened FNS-cement paste with steam curing at 60 °C or 80 °C increased by 8.2 % or 33.8 %, and the connected porosity decreased by 18.9 % or 17.3 %. And MgO in the ferronickel slag exists as Mg2SiO4 in raw materials and enters the C-S-H gel with the formation of M-S-H gel during the secondary hydration stage. This study provides a theoretical basis for solid waste-based concrete and promotes the recycling, conservation, and resources of solid waste in building materials.

A Green Economy Approach to Solid Waste Management in Minna, Nigeria

This study is based on solid waste recycling activities in Minna, Nigeria. The objectives of the study are to take inventory of recycling outlets, to examine the recycling inputs and the products produced by the recyclers, to assess the operating environment of the recycling cluster and to investigate the livelihood opportunities that recycling generates. The result shows that the recycling cluster occupies an area of 0.64 hectares that accommodates 141 recycling outlets with about 40% of the outlets occupying below the standard shop size of 7.2m2. The recycling outlets use 18 types of recovered materials to reproduce 27 varieties of products. Each recycling outlet engages about 3.4 persons and offers training to an average of 6 persons each. In general, the sector contributes to creation of employment, income generation, skill development, asset building and social capital formation.

Experimental study on physical and mechanical properties of foamed lightweight soil for underwater backfilling

In this paper, foam lightweight soil was prepared from river sand and cinder from thermal power plants as raw materials. Combined with the requirements of embankment pouring and backfilling, the strength development, compressive strength, softening coefficient, water absorption, and other physical and mechanical properties of two different aggregate foam lightweight soils were compared. The applicability of foam light soil with river sand and cinder as aggregate in pouring and backfilling of hydraulic structures is analyzed and studied, which provides application and reference for related engineering and solid waste recycling.

Quantitative Carbon Changes of Selected Organic Fractions during the Aerobic Biological Recycling of Biodegradable Municipal Solid Waste (MSW) as a Potential Soil Environment Improving Amendment—A Case Study

The aim of the investigation was to determine the quantitative changes of selected organic compounds during composting of municipal solid wastes (MSWs). The object of the study was a differently matured compost produced according the to open pile/windrow semi-dynamic technology from selectively collected biodegradable municipal solid waste. During the experiment, the temperature and moisture of the composted wastes were monitored. In the collected samples—taken from differently matured compost—the total organic carbon (TOC) and total nitrogen (TN) were determined. The organic matter fractionation method described by Stevenson and Adani et al. was adopted, which allows to determine the carbon content of the following groups of organic compounds: hydrophobic (HSC), hydrophilic (WEOC), acidophilic (CAC), cellulose (CCEL), core-HA (ligno-humic, CALK) and residual carbon (non-hydrolysing, CR). The TOC and TN content, as well as the origin and quality of the starting materials, allow the product tested to be classified for fertiliser purposes. The most intense changes were observed during the thermophilic composting phase. In spite of the optimal technological conditions of the process, the predominance of the CR and CCEL fraction was observed, and the share of humic compounds did not exceed 30% TOC. The investigated compost met legal, ecological and economic criteria for products of biological recycling, thus can be used as a good organic amendment to improve the soil organic matter balance, stimulate the soil biodiversity and carbon sequestration.

Study on Shear Characteristics and Failure Mechanism of Inclined Layered Backfill in Mining Solid Waste Utilization

To eliminate the massive accumulation of tailings and promote the recycling of mine solid waste to develop green mining, a two-layered cemented paste backfill (CPB) with layering angles of 5°, 10°, 15°, 20° and 25° and complete CPB were prepared to conduct direct shear experiments; thus, the effect of the layering angle on their shear mechanical properties can be investigated. Meanwhile, the particle flow analysis program PFC 2D was used to simulate the micro-crack propagation law and reveal the damage mechanism. The results showed that the layered structure weakens the integrity of CPB and significantly reduces its shear strength, cohesion and internal friction angle. When the layered angle increased from 20° to 25°, the shear strength under normal stress of 100 kPa was decreased by 35.13% and cohesion by 43.43%. As the layered angle increased from 5° to 25°, the internal friction angle decreased first and then increased and reached the minimum when the layered angle was 15°. With the increase in the layered angle, the layered CPB gradually generated tension cracks along the layered surface, and the number of cracks gradually increased. The failure mode of each specimen is mainly a shear crack through the shear surface failure, crack expansion in the middle of shear surface on the upper and lower sides of the spindle-shaped failure and an inverted Z-shaped conjugate shear failure. This research can provide a substantial reference in the design and application of layered CPB in underground mines.

The impact of the application of environmental management system on the solid waste recycling system to achieve sustainability

The impact of the application of environmental management system on the solid waste recycling system to achieve sustainability

Recycling of hazardous and industrial solid waste as raw materials for preparing novel high-temperature-resistant sulfoaluminate-magnesia aluminum spinel cement

Secondary aluminum dross from aluminum smelter plants is a hazardous waste with no effective method for realizing its disposal and utilization safely. This research evaluated the potential of preparing novel high-temperature-resistant sulfoaluminate-magnesia aluminum spinel (SAC-MA) cement using secondary aluminum dross, carbide slag, magnesite tailings and desulfurization gypsum as the raw materials for the replacement of natural resources. Furthermore, the leaching toxicity of unroasted and preroasted secondary aluminum dross was analyzed. The mineral phase and microstructure of clinkers and hydration products were also considered and their effect on the mechanical properties and microstructure of the high-temperature-resistant SAC-MA samples was researched. The experimental results showed that roasting detoxification was effective in realizing the safe disposal of secondary aluminum dross and magnesia aluminum spinel, dicalcium silicate and Fe→Al substitutional ye'elimite formed in the SAC-MA clinker after the sintering using hazardous and industrial solid waste. Improved high temperature resistance of SAC was also observed. High temperature induced the decomposition of ettringite and led to its structural relaxation. Surprisingly, the existence of magnesia aluminum spinel made the structure of ettringite smaller and decreased the decomposition degree of ettringite, as well as improving the high temperature resistance of SAC. Changes in the main skeletal structures of ettringite and AH3 gel were not noticeable, which still had good stability at 200 °C for the SAC-MA sample. However, ettringite gradually became amorphous at 200 °C for the SAC sample. These results strongly indicated that using hazardous waste, including secondary aluminum dross, as raw materials for preparing SAC-MA was far superior to SAC with regards to high temperature resistance. This study contributed a novel example of converting hazardous and industrial solid waste into high value-added materials and may open a new approach for synthesizing high temperature-resistant SAC-MA cement from low-cost feedstocks.

The Fuzzy DEA-Based Manufacturing Service Efficiency Evaluation and Ranking Approach for a Parallel Two-Stage Structure of a Complex Product System on the Example of Solid Waste Recycling

Accurate production efficiency evaluation can assist enterprises in adjusting production strategies, improving production efficiency, and, thereby, weakening environmental impacts. However, the current studies on production efficiency evaluation do not accurately consider interactions inside the production system in parallel production processes. Based on the concept of the manufacturing service, this paper describes the production process of a complex product system (CoPS) with a manufacturing service chain. An efficiency calculation model based on the triangular intuitionistic fuzzy number–solid waste recycling–super-efficiency data envelopment analysis (TIFN-SWR-SDEA) is proposed under the consideration of the internal parallel structure of the production system on the example of solid waste recycling. Additionally, the technique for order preference by similarity to ideal solution (TOPSIS) method and the entropy weight method were combined to determine the proportion of solid waste recycling, and an improved proposed index rank (PIR) method was employed to rank the efficiency interval results. Finally, the effectiveness and superiority of the method were verified by comparative analysis. The results show that the overall efficiency of the CoPS production system can be improved by using green manufacturing technology, increasing the recycling of renewable resources, using clean energy, and improving the utilization rate of materials in the production process.

Can Circular Economy Legislation Promote Pollution Reduction? Evidence from Urban Mining Pilot Cities in China

Major economies, such as the United States, European Union (EU), Japan, and China have enacted Circular Economy Promotion Laws (CEPLs) to promote the development of the recycling industry. The Urban Mining Pilot Policy (UMPP) is an essential provision of the CEPL in China, which promotes a circular economy and environmentally friendly industries and society. In China, the Urban Mining Pilot City (UMPC) program facilitates the addressing of the negative environmental impacts of industrial and urban waste, and conservation of scarce primary resources, which are necessary for sustainable industrialization and urban sustainability in developing countries. In the present study, a time-varying difference-in-difference analysis of city-level panel data was conducted to investigate the impact of the UMPC program on pollution reduction in China. The results indicated that the UMPC program has improved municipal waste management efficiency and environmental quality significantly, with robust results across various models and datasets. Additionally, the mediation test showed the positive impacts of the UMPC program are mainly associated with the economy-of-scale effects. Finally, the UMPP had geographical and social-economic heterogeneous effects. To the best of our knowledge, this is the first study to quantify the impact of the UMPC program on recyclable solid waste management and pollution reduction in urban China, with potential contributions to resource and environmental economics.

Effects of alkali-treated plant wastewater on the properties and microstructures of alkali-activated composites

Naturally available plants such as fiber, straw, sawdust, and wood used as reinforcing additives in building materials require an alkali treatment to reduce the moisture sensitivity of additives and to interlock matrix and additive. However, the discharge of alkali-treated plant wastewater (ATPW) is extremely detrimental to the environment. The purpose of this study is to evaluate the effects of recycled ATPW from NaOH-treated sisal leaves, poplar leaves, poplar stems, and corn stems on the characteristics and microstructures of alkali-activated composite materials (AACMs) made from solid wastes. The ATPWs were produced by soaking green and dead plants for 24 h in a 15% NaOH solution. The AACMs were manufactured using ATPW as an alkaline activator and a mixture of slag powder, red mud, fly ash, and steel slag as a binder. The fresh and hardened properties, such as electrical conductivity (EC), fluidity, flexural strength, compressive strength, and density, were examined along with drying shrinkage resistance. Furthermore, SEM, EDS, CT, and FTIR techniques were used to observe and evaluate the pore distributions, morphologies, and products. The results demonstrate that the effects of ATPWs produced from dead sisal leaves were remarkable on the properties and microstructures of AACMs. The sample (DSL) with ATPW exhibits an increase of 43.08% in fluidity and a drop of 50.00% in EC, 44.30% in density, 34.25% in dry shrinkage, 84.44% in flexural strength, and 88.50% in compressive strength, relative to the control without ATPW. Moreover, AACMs physically sequester the organic components of ATPW during the early stage of hardening. The ATPW serves as a unique physical foaming agent in AACMs. The results provide original data on the dual recycling of industrial wastewater and solid waste to promote clean operations.

Performance optimization and characterization of loess-slag-based geopolymer composite: A new sustainable green material for backfill

• Cemented backfill preparation with loess and slag. • Effect of loess percentage on workability of the cemented backfill. • Effects of loess percentage and curing time on failure modes. • Coupling effects of loess percentage and curing time on strength and microstructure. • The optimum ratio for loess to slag of the cemented backfill. Recycling idle materials and industrial solid wastes to prepare cemented backfill is one of the best ways to achieve green mining. In this study, we synthesized a loess-slag-based geopolymer composite (LSGC) by utilizing loess and slag (ground granulated blast-furnace slag) as cementing materials, sodium silicate as an alkaline activator, and recycled waste sandstone as aggregates. Through the tests of uniaxial compression, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), the workability and setting time, uniaxial compressive strength (UCS), and the microstructure characteristics with the coupling effect of curing time ( t ) and loess percentage (LP), as well as the best loess slag ratio were finally determined. The results indicate that the increase in LP can enhance the workability and the setting time of LSGC paste. The UCS of LSGC increases with curing time, with the greatest rise occurring during the first three days, and it is negatively correlated with LP. The loess gel in LSGC is sodium-aluminate-silicate-hydrate (N-A-S-H), while the slag gel is calcium-(aluminate)-silicate-hydrate (C-(A)-S-H). Finally, it is revealed that 1:1 is the optimum ratio for loess to slag. At this ratio, the workability and setting time of LSGC are qualified, the 28-day UCS is about 14.61 MPa, and the microstructure is dense and stable. This study is of great significance in promoting the recycling of idle materials and industrial solid wastes as well as green backfill mining.

Municipal Solid Waste Estimation and Management—Challenges and Lessons From Regional Studies of West Bengal (India)

Solid waste management is a multidimensional challenge, especially in developing countries like India. This paper presents the findings of a study carried out in thirty-two urban local bodies of West Bengal to determine the solid waste generation rate and waste composition based on field surveys covering 5,000 households. The services delivered for solid waste management, the institutional arrangements and the constraints in meeting the prescribed standards have been studied. The level of satisfaction of the citizens and related socio-economic factors were also covered under the study. The collected data was analysed to relate waste generation, composition, segregation and community participation. This study also aimed to contribute to a better understanding of household waste management behaviour by examining solid waste management practices and attitudes. Results from this study will provide inputs to the environmental and waste management planners in their decisions on solid waste segregation and recycling activities in the municipalities and municipal corporations.

Determinants of the Willingness to Pay for Solid Waste Recycling among Households in Ilemela, Tanzania

This study aimed to investigate the determinants of willingness to pay for solid wastes recycling among households in Ilemela District, Mwanza-Tanzania. The study design was a cross-sectional survey design which was conducted among households residing in Ilemela District. A multistage sampling technique was useful for selecting representative samples from every ward. Structured questionnaires were used to obtain data from study participants. Data was analyzed using descriptive statistics, logistic regression was used in analyzing the factors influencing household’s willingness to pay for solid waste recycling and ordinary least square regression was used to estimate the effect of socio-economic factors on the amount households were willing to pay for solid wastes in Ilemela District. The findings of the study show that majority of households were not willing to pay for solid waste recycling in Ilemela District, Mwanza region.The willingness to pay for solid waste recycling was associated with age of the household head, marital status, and education. Information dissemination and logarithm of household’s income while the effect of socio-economic factors on amount households were willing to pay for solid waste recycling was associated with the marital status (married households), households’ years of education, information dissemination on solid waste recycling and logarithm of income was statistically significant in influencing the amount households are willing to pay for solid waste recycling. The study recommends that the government and other interested stakeholders on solid waste management should invest more on education and awareness about importance of waste management to the mass using different mechanisms.

Waste-to-Energy Generation: Complex Efficiency Analysis of Modern Technologies

Recycling of Municipal Solid Waste (MSW) is a significant challenge all over the world. Waste-to-Energy generation solves the problem of MSW recycling and produces power for urban territories. In this study, the researchers implemented complex economic and ecological efficiency analyses of modern Waste-to-Energy technologies. The fundamental challenge of modern Waste-to-Energy generations is finding the balance between economics, ecology, and productivity. Thus, to assess the effectiveness of various thermal technologies, statistics from enterprises were used. The Balanced Scorecard (BSC) method was implemented to calculate an integral effectiveness of a particular Waste-to-Energy technological approach. Environmental and economic analysess of thermal MSW disposal technologies was carried out by selecting the data from at least 146 functioning plants in Canada, China, Finland, France, Germany, Italy, Japan, the Netherlands, Sweden, and Thailand. The research results confirm that gasification technology was the most promising and the most environmentally and cost effective. Incineration Moving Grate technology was the least effective and attractive Waste-to-Energy technology according to the results of the environmental and economic efficiency assessments. The research results can be used for urban planning in waste recycling projects and the new energy national and municipal agenda. The research results can also be useful for municipal strategic energy and sustainable plans and programs.

Carbon-calcium composite conversion of calcium carbide-acetylene system: On the imperative roles of carbon capture and solid waste recycling

As an important national basic industry in China, the production of calcium carbide faced with huge pressure on energy conservation and emission reduction because of the CO2 emission and solid waste carbide slag. Therefore, it is necessary to realize the recycling of carbon and calcium in the production process of calcium carbide. A novel system of carbon-calcium compound conversion for calcium carbide-acetylene production was proposed in this work, which combines two-stage carbon capture and calcium carbide waste slag reuse processes to achieve CO2 enrichment and calcium cycle. Based on the simulation data, the proposed system was comprehensively evaluated by material conversion, exergy and exergoeconomic analyses. It was found that the improved process performed better with an effective C, H, Ca atomic conversion rate for carbide furnace of 85.41% and CO2 capture efficiency of 90.35%, compared with the referenced process of 64.51% and 0, respectively. The exergoeconomic analysis results suggested that more focus should be put on carbide furnace, acetylene reactor, re-carbonization furnace, gasifier and calciner since they are the top five of capital investments and exergy destruction. Besides, the carbide furnace, acetylene reactor, re-carbonization furnace and gasifier have relatively lower exergoeconomic factor (fk) values of 1.00%, 0.93%, 2.27% and 3.07%, respectively, indicating that exergy destruction costs of these components can be decreased with the improvement of system thermodynamic and equipment performance. Furthermore, the calcium looping process formed based on the improved oxy-thermal method (OTM) process, using the captured CO2 to mineralize carbide slag to form another calcification cycle for the production of calcium carbide-acetylene, has a higher exergy efficiency of 48.97% than the referenced process of 47.85%, and also achieves the lowest carbon emissions and the obvious reduction in CaO input. Results revealed that the proposed calcium looping system with high-efficiency, low-carbon and clean for calcium carbide-acetylene production, could be a promising process for carbon emission reduction in practical applications.

Investigation of Knowledge, Attitude, and Practice of Women in Solid Waste Recycling in Kashan

Introduction: Recycling is one of the main elements of comprehensive waste management. This study aims to investigate the knowledge, attitude, and practice of women towards solid waste recycling in Kashan.
 Methods: In this descriptive study, 368 women were selected from households by random sampling. The data were analyzed using SPSS software version 22 with descriptive statistics and analytical tests at a significance level of 0.05.
 Results: The scores of knowledge, attitude, and practice of women were 4.1±83.74, 14.3±75.54, and 4.1±45.29, respectively. The results showed that 37.2% of women in Kashan had good knowledge, 43.1% had good attitude, and 57.2% had good performance towards solid waste recycling. A significant difference was observed between the level of performance among different educational groups in terms of attitude and knowledge, between the level of knowledge of individuals and occupational groups, and between the level of knowledge of people in terms of marital status, and between different groups of owners and tenants in terms of knowledge.
 Conclusion: It seems that the performance of women in Kashan was at an acceptable level compared to others participants in other studies.

EVALUATION OF HOUSEHOLDS‘ PRACTICES TOWARDS SOLID WASTE MANAGEMENT

Solid waste is the organic and inorganic waste materials such as product packaging, furniture,clothing, bottles, kitchen refuse, paper, paint cans, batteries, etc. Management of solid waste; is theprocess of collection, treatment, and recycling of solid waste in a sustainable manner to avoid theadverse effect on the environment. In Sudan waste management is poor and solid wastes aredumped along roadsides and into open areas, endangering health and attracting vermin. Thisdescriptive cross-sectional community-based study with the aim to assess the practices of thehouseholds towards the management of house refuse was conducted in Al-Ozozab, Khartoum,2019. Four hundred households were selected by multi stage sampling techniques from thecommunity and data were collected by questionnaire and observation checklist. Most types (83.3%)of containers used for the waste store were plastic bags. All (100%) of the respondents cover the wastecontainer. Almost all the respondents wash their hands with water and soaps after cleaning. 50.7%of respondents hear about hazardous domestic waste from TV and (19.3%) from radio. More thanhalf (53.3%) of the houses‘ level of cleanliness was very good. Factors such as age, marital status,education level, family size, and monthly income significantly influence waste managementpractice. It can be concluded that the household has good level of practice towards solid wastemanagement.

Solid Waste Management And Recycling Practices Among PPR Sri Pantai Residents: A Move Towards Sustainability

Solid Waste Management And Recycling Practices Among PPR Sri Pantai Residents: A Move Towards Sustainability

Solid waste generation from the hotel industry in the coastal tourism cities of Vietnam

While the tourism and hospitality sectors in Vietnam have been rapidly developing, the increasing consumption of natural resources and production of associated waste, especially in coastal and island sites, threaten these marine areas with pollution. This study provides data on solid waste from 10 hotels in three coastal provinces of Vietnam, namely, Hai Phong, Quang Nam and Phu Yen. The results indicated significant percentages and volumes of organic waste especially from large-scale hotels with in-house food services like restaurants and bars. The proportions of organic and recyclable solid waste from all three surveyed cities ranged between 35-84% and 10-27%, respectively. Plastic waste accounted for a relatively high proportion of solid waste ranging from 27 to 60% total solid waste by volume and from 7 to 30% by weight. In particular, PET plastic made up the highest proportion of solid waste in Cat Ba town (52.41%) and Tuy Hoa city (39.81%) while single-layer plastic accounted for the highest proportion (29.55%) in Hoi An city. Plastic waste from food packaging, related to the cultural habits of guests that bring instant food items during their stay, was identified as an important issue, which reflects a valuable but presently wasted potential resource. These quantities of hotel solid waste can be recovered and provide additional environmental and health benefits to the community by not being dumped, landfilled, or openly burned.