Municipal Solid Waste Treatment Research Articles

Physical Chemistry Supports Circular Economy: Toward a Viable Use of Products from the Pyrolysis of a Refuse-Derived Fuel and Granulated Scrap Tire Rubber as Bitumen Additives

The production and maintenance of road pavements consume resources and produce wastes that are disposed of in landfills. To make more sustainable this activity, we have envisioned a method based on a circular use of residues (oil and char) from municipal solid waste pyrolysis as useful additives for producing improved asphalts and for recycling old asphalts to generate new ones, reducing at the same time the consumption of resources for the production of new road pavements and the disposal of wastes to landfills. This work aims to show the feasibility of the integration of two processes (thermal treatment of municipal solid waste on one side, and that of road pavement production on the other side) where the products deriving from waste pyrolysis become added-value materials to improve the quality of road pavements. In this contribution, we presented the effect of pyrolysis product addition on asphalt binder (bitumen) preparation and aging. Solid and liquid products, deriving from the pyrolysis of two kinds of wastes (refused derived fuel (RDF) and granulated rubber tyre waste), have been used for the preparation of asphalt binder samples. Rheological tests have been performed to determine the mechanical properties of neat asphalt binder (bitumen) and those enriched with pyrolysis derived products. Measurements to evaluate possible anti-aging effects have been also performed. The collected results indicate that char addition strengthens the overall bitumen intermolecular structure while bio-oil addition exerts a rejuvenating activity.

Characteristics of Municipal Solid Waste in Some Urban Agglomeration in the Past Five Years

The treatment and disposal of municipal solid waste has increasingly become a common concern around the world, and the characteristics of municipal solid waste(MSW) are an important basis for the selection of terminal treatment methods. In this study, more than 400 MSW samples from over 30 cities across China were collected, and the basic physical and chemical properties, such as the physical composition, pollutant content, and calorific value, were analyzed. Shenzhen was taken as an example to analyze the influence of time and waste sorting measures on the physical and chemical characteristics of MSW. The correlation model between MSW composition and calorific value was established using partial least squares(PLS) regression, and the model was verified. The results showed that with per capita GDP increasing by 10,000 yuan, per capita MSW production and the low calorific value of MSW increased by 0.1 kg·(person·d)-1 and 373.8 kJ·kg-1, respectively. However, when per capita GDP was less than 60,000 yuan, the correlation between per capita GDP and per capita MSW production was relatively poor. Kitchen waste was still the most abundant component of MSW, and the content of most samples was between 40% and 60%. The combustible content of rubber/plastic and paper was relatively high, between 20%-30% and 10%-20%, respectively. The inorganic content did not usually exceed 5%, and the moisture content of the MSW was between 50% and 60%. After the implementation of waste classification in 2019, the content of kitchen waste in MSW had been significantly reduced, the content of rubber/plastic had increased, and other components had not changed much. Additionally, the calorific value of waste had been improved to a certain extent. The pollution element contents in MSW, S Cl, and N were all below 1%, and the average value was:N>Cl>S. The contents of Hg, As, Cr, Cd, and Pb in MSW samples did not change significantly with the composition and sampling time, and the content of Pb and Cr in MSW was affected by the environmental background value. The model analysis revealed that rubber/plastics and moisture content were the main variables that affected the calorific value of MSW. The deviation between the measured value and the predicted value was less than 20% for 85.96% of the samples. The model established in this study can meet the needs of the prediction of the calorific value of MSW.

Efficient recovery and characterization of humic acids from municipal and manure composts: A comparative study

The recovery of humic acids from low-quality compost obtained in municipal solid waste treatment plants provides opportunities for its valorization. This study compares the recovery and properties of the humic acids obtained from municipal mixed waste compost (MMWC) and manure compost. The effects of temperature, time, and KOH concentration on the ratio of humic acids in the extracted liquid and the content of organic carbon of the precipitates were investigated by response surface methodology. Optimal conditions were 30 °C and 24 h for both composts, with a KOH concentration of 0.53 M for MMWC and 0.25 M for manure compost. The manure compost provided a liquid extract richer in humic acids than MMWC (76.6 % vs. 33.7 %), but the precipitates presented similar organic carbon contents (38.1 % vs. 42.4 %). Regarding composition, both humic acids presented higher organic carbon and nitrogen contents than the composts used as feedstock. The extraction and further precipitation of humic acids reduced the concentration of heavy metals. Humic acids from manure compost have a slightly higher average molecular weight (2650 Da) than those from MMWC (1980 Da), while both present similar C/N ratios and degree of aromaticity. Most contaminants of emerging concern present in the original composts were not detected in the humic acids. Thus, it was demonstrated that MMWC constitutes an attractive source of humic acids with properties similar to those obtained from a high-quality compost and, therefore, with potential economic value.

Prediction of carbon emissions from municipal solid waste treatment in 31 provinces and cities in China under the shared socio-economic pathways

In order to reduce greenhouse gas (GHG) emissions from the municipal solid waste (MSW) sector, it is essential to describe its greenhouse gas emission patterns and propose appropriate mitigation measures. Therefore, this study predicts the greenhouse gas emissions of urban domestic waste treatment by combining the Intergovernmental Panel on Climate Change (IPCC), shared socio-economic pathways and in-depth learning model. Under the hypothetical policy scenario and the shared socio-economic pathways (SSPs), the greenhouse gas emissions from municipal solid waste treatment in 31 provinces and cities in China by 2030 are analyzed. Combined with the model comparison results, the bidirectional long and short-term memory neural network model has better prediction accuracy than the other models, with an average mean absolute percentage error of 9.68% for 31 provinces and cities, indicating good applicability. Scenario analysis shows that greenhouse gas emissions from municipal solid waste disposal can be significantly reduced only after the implementation of municipal solid waste classification. Scenario 3 (S3) of waste segregation will produce the most GHG emissions, and switching to Scenario 5 (S5) of waste segregation will produce significantly less GHG emissions. Finally, the paper makes policy recommendations on the priority areas of urban domestic waste classification, waste source classification and recycling, and the structure of urban municipal solid waste treatment.

The Urban-Industrial metabolism: contribution of waste recycling to the circular economy objectives within the construction sector

The construction and buildings sector is facing an urgent need to reduce GHG emissions and ensure efficient resource utilization while minimizing waste in order to comply with climate change policies and circular economy initiatives. Alkali-activated materials, as an alternative binder to CO2-intensive conventional cement, show potential in utilizing waste streams from urban environments in their production technology, thereby reducing CO2 emissions. This study examines two waste streams generated in Switzerland: incineration ashes from municipal solid waste treatment facilities and mineral wool waste from building stock renovation and demolition activities. Geospatial analysis is combined with LCA methods to assess optimal scenarios for waste recycling, utilizing a multi-objective optimization framework based on mixed integer linear programming. The objectives are to minimize the environmental impacts and costs associated with alternative supply chain networks, thereby identifying optimal locations for waste pre-treatment and concrete manufacturing. The proposed scenarios demonstrate reductions of 56% in global warming potential and 29% in costs when compared to the business-as-usual scenario of conventional cement concrete use and waste landfilling. Results show that recycling of urban waste streams in alternative concrete can reduce GHG emissions of industry and heavy transportation sectors by 0.46 mt. CO2 eq. by year 2030, equivalent to 23% and 4% of the Swiss carbon budget reduction targets for these sectors.

Greenhouse gas emissions mitigation potential of municipal solid waste management: A case study of 13 prefecture-level cities in Jiangsu Province, China

Municipal solid waste (MSW) treatment is one of the main anthropogenic sources of greenhouse gases (GHGs). To mitigate the GHG emissions of the MSW sector, it is crucial to describe their emissions evolutions and mechanisms and propose localized mitigation measures on that basis. The logarithmic mean Divisia index model is used to identify the driving forces of MSW-related GHG emissions and explore the mitigation potential. Jiangsu, a typical province in China with 13 prefecture-level cities, is selected as the case study. The results showed that GHG emissions from Jiangsu's MSW treatment has increased by nearly 2.5 Mt in the last 20 years, as incineration replaces landfills. Economic development was the dominant positive driving force, and MSW generation intensity was the dominant negative driving force. Scenario analysis revealed that the carbon peak of MSW management could appear if MSW source separation and recycling (SSR) were implemented, reducing GHG accumulation emissions by approximately 0.3–0.4 Gt during 2022–2060. Referencing the SSR of the Shanghai pattern will generate the greatest mitigation potential of GHG emissions among the different scenario designs. Finally, policy recommendations for priority cities, consideration of population and economic factors, optimization of MSW treatment structures and improvements to SSR are proposed, which could help local- and national-level decision makers in China and other countries design policy guides to promote carbon neutrality, while simultaneously linking current research areas to waste management practices as well as promoting practices in environment and sustainability.

Feasibility Analysis of Municipal Solid Waste Incineration for Harmless Treatment of Potentially Virulent Waste

The outbreak of major health emergencies, such as the COVID-19 pandemic, has posed numerous challenges to waste management. Environmentally sound treatment of such epidemic-related municipal solid waste (MSW) plays a vital role in interrupting virus transmission. In this study, the furnace type, incineration process and control parameters of an MSW incinerator were comparatively analyzed with those of a medical waste incinerator and hazardous waste incinerator according to China’s MSW incineration pollution control standards. In addition, changes in flue gas emissions data before, during and after the outbreak of the pandemic were empirically analyzed. The study revealed the following: (1) the feasibility of MSW incinerators to meet the harmless disposal of potentially viral municipal solid waste (PVMSW); (2) the priority order of incinerator types for MSW incinerators in the disposal of potentially virulent waste was grate furnace incinerator > fluidized bed incinerator > cement kiln; and (3) when MSW incinerators treated PVMSW, the emissions of dioxin compounds in the flue gas fluctuated between 0.00052 and 0.031 ng TEQ/m3, HCl emissions fluctuated between 1.6 and 23.742 mg/m3, CO emissions fluctuated between 0.18 and 59.15 mg/m3, heavy metal emissions fluctuated between 0.000008 and 0.855 mg/m3, and particulate matter emissions fluctuated between 0.64 and 12.13 mg/m3. All emissions met the flue gas emission standards. This study verified the feasibility of using MSW incinerators to treat PVMSW during a sudden major pandemic and provided a theoretical basis for the environmentally sound collaborative treatment of PVMSW and a reference for the emergency management and sustainable development of MSW.

Admissibility Grid to Support the Decision for the Preferential Routing of Portuguese Endogenous Waste Biomass for the Production of Biogas, Advanced Biofuels, Electricity and Heat

A methodology was developed to assess the allocation of different types of endogenous waste biomass to eight technologies for producing electricity, heat, biogas and advanced biofuels. It was based on the identification of key physicochemical parameters for each conversion process and the definition of limit values for each parameter, applied to two different matrices of waste biomass. This enabled the creation of one Admissibility Grid with target values per type of waste biomass and conversion technology, applicable to a decision process in the routing to energy production. The construction of the grid was based on the evaluation of 24 types of waste biomass, corresponding to 48 sets of samples tested, for which a detailed physicochemical characterization and an admissibility assessment were made. The samples were collected from Municipal Solid Waste treatment facilities, sewage sludges, agro-industrial companies, poultry farms, and pulp and paper industries. The conversion technologies and energy products considered were (trans)esterification to fatty acid methyl esters, anaerobic digestion to methane, fermentation to bioethanol, dark fermentation to biohydrogen, combustion to electricity and heat, gasification to syngas, and pyrolysis and hydrothermal liquefaction to bio-oils. The validation of the Admissibility Grid was based on the determination of conversion rates and product yields over 23 case studies that were selected according to the best combinations of waste biomass type versus technological solution and energy product.

Numerical investigation of the effect of the location of an immersed tube in a fluidized bed on heat transfer of surface-to-bed

The study of heat transfer characteristics within an external heat exchanger (EHE) in circulating fluidized bed (CFB) boilers for the treatment of municipal solid waste (MSW) is of great significance for improving energy utilization. An Eulerian-Eulerian approach coupled with the kinetic theory of granular flow (KTGF) was used in this work and the effect of the immersed tube location on hydrodynamics and heat transfer characteristics in a gas-solid fluidized bed was investigated. The model accuracy was validated by the reference result. It was shown that the tube location has a significant effect on heat transfer of surface-to-bed, with increasing height of the tube from 0.2 m to 0.5 m, the average heat transfer coefficient (HTC) of the immersed surface decreased from 302 to 274 W/(m2K). Meanwhile, the specific process of particle renewal on the tube surface and the impact of the particle renewal mechanism on heat transfer were investigated.

Impact of the New Electricity Remuneration Scheme on the Waste-to-Energy Recovery Activity in Portugal

The remuneration scheme for the electricity produced by Waste-to-Energy (WtE) recovery plants has changed recently in Portugal according to 2020 legislation. The new model, linking the electricity remuneration from WtE plants to the spot electricity prices, is expected to bring greater uncertainty in the waste activity, which is a novelty for the sector. In Portugal, Valorsul is the municipal waste treatment entity responsible for the recovery and treatment of municipal solid waste (MSW) produced in 19 municipalities in the Lisbon area. This paper highlights the impact of the new Portuguese electricity remuneration scheme for electricity from waste on Valorsul’s WtE plant. For this purpose, the new remuneration scheme is modeled and simulated based on electricity spot market price scenarios, which are compared with the base case scenario of the former remuneration scheme. Considering different electricity prices for the electricity produced by the WtE plant, the present study anticipates the consequences of the gate-fee of such regulatory changes. Results show that any price changes in the electricity remuneration scheme are offset by equivalent changes in the waste gate-fee. Consequently, the change in the remuneration of the electricity from the WtE plant is, in fact, neutral for the Valorsul accounts and lower revenues from the electricity generation activity of the WtE will negatively impact the gate-fee prices paid by the waste users.

Use of life cycle assessment for estimating impacts of waste-to-energy technologies in solid waste management systems: the case of Buenos Aires, Argentina.

Analysing municipal solid waste (MSW) management scenarios is relevant for planning future policies and actions toward a circular economy. Life cycle assessment (LCA) is appropriate for evaluating technologies of MSW treatment and their environmental impacts. However, in developing countries, advanced assessments are difficult to introduce due to the lack of technical knowledge, data and financial support. This research aims to assess the main potentialities of the introduction of waste-to-energy (WtE) systems in a developing Argentinean urban area considering the existing regulations about MSW recycling goals. The study was conducted with WRATE software and the proposed scenarios were current management, grate incineration of raw MSW and incineration of solid recovered fuel (SRF). In addition, a sensitivity analysis on the energy matrix was included. It was found that the production of SRF allows increasing the energy generation from waste by 200% and reducing the environmental impact of about 10% regarding the current MSW management system. Acidification Potential and Abiotic Depletion Potential were sensitive to changes in electricity mix. Results showed that if MSW reduction goals are achieved, changes in MSW composition will affect the performance of WtE plants and, in some cases, they will be not technically feasible. The outcomes of this study can be of interest for developing countries stakeholders and practitioners interested in LCA and sustainable MSW management.

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.

From air to airway: Dynamics and risk of inhalable bacteria in municipal solid waste treatment systems

Municipal solid waste treatment (MSWT) system emits a cocktail of microorganisms that jeopardize environmental and public health. However, the dynamics and risks of airborne microbiota associated with MSWT are poorly understood. Here, we analyzed the bacterial community of inhalable air particulates (PM10, n = 71) and the potentially exposed on-site workers’ throat swabs (n = 30) along with waste treatment chain in Shanghai, the largest city of China. Overall, the airborne bacteria varied largely in composition and abundance during the treatment (P < 0.05), especially in winter. Compared to the air conditions, MSWT-sources that contributed to 15 ∼ 70% of airborne bacteria more heavily influenced the PM10-laden bacterial communities (PLS-SEM, β = 0.40, P < 0.05). Moreover, our year-span analysis found PM10 as an important media spreading pathogens (104 ∼ 108 copies/day) into on-site workers. The machine-learning identified Lactobacillus and Streptococcus as pharynx-niched featured biomarker in summer and Rhodococcus and Capnocytophaga in winter (RandomForest, ntree = 500, mtry = 10, cross = 10, OOB = 0%), which closely related to their airborne counterparts (Procrustes test, P < 0.05), suggesting that MSWT a dynamic hotspot of airborne bacteria with the pronounced inhalable risks to the neighboring communities.

Achieving energy self-sufficiency in wastewater treatment plants by integrating municipal solid waste treatment: A process design study in Spain

Water-energy nexus is a highlighted topic nowadays, particularly, the energy consumption in wastewater treatment plants (WWTPs) is becoming an important issue. WWTPs typically consume more energy than the one that can be obtained from the biogas produced from sludge anaerobic digestion. In this work, a process-level analysis is presented to study the feasibility of integrating wastewater and municipal solid waste (MSW) treatment to achieve the energetically self-sustainable operation of a WWTP. The influence of the climate of different regions across the Iberian Peninsula on the energy requirements has also been evaluated. Mesophilic and thermophilic digestion are compared in Salamanca as a case base, and the optimal digestion temperature is also evaluated, finding a value of 30∘C. Moreover, in all cities considered, it is necessary for MSW to provide between 37% and 40% of the facility energy consumption corresponding to around 0.19 kg of MSW per kg of sludge, with a small difference between cities. From an economic point of view, an investment between 0.09 and 0.16 €/kg of sewage sludge is required for the integrated process. Therefore, this techno-economic assessment demonstrates the feasibility of integrating these two treatments for a fully self-sufficient and sustainable process.

Estimation of Greenhouse Gas Emission from Organic Fraction of Municipal Solid Waste Treatment

Estimation of Greenhouse Gas Emission from Organic Fraction of Municipal Solid Waste Treatment

Global trends in municipal solid waste treatment technologies through the lens of sustainable energy development opportunity

Global trends in municipal solid waste treatment technologies through the lens of sustainable energy development opportunity

High potential of coupling the source-separation and incineration promotion to reduce costs based on city-level cost-benefit analysis of municipal solid waste management strategies in China

To screen the optimum strategy of municipal solid waste (MSW) management toward the goal “zero-waste city” in China, in this study, a tailored system including six indicators of waste of land resource, greenhouse gas emissions, human toxicity, energy recovery, biomass recovery, and paper/plastic recovery were developed and total costs were quantified based on city-level cost-benefit analysis considering the city socioeconomic characteristics. Results show that the systemic change scenario which couples the MSW source-separation, incineration promotion, and biosolid land application has the best performance in total net cost reduction by US$154 billion during 2021–2030, of which US$80 billion is external cost. Due to the change in external cost of land resources, the marginal cost of MSW treatment varies significantly with city groups, with megalopolises being 3 times as other city groups. The high external cost of land resources further underscores the importance of reducing the final landfilled waste mass for megalopolises.

Multi-criteria group decision-making method in disposal of municipal solid waste based on cubic Pythagorean fuzzy EDAS approach with incomplete weight information

Municipal solid waste management (MSWM) has always been a typical issue in India. The rapid population growth, impetuous adoption of modern lifestyle, and fast urbanization resulted in India’s swift generation of complicated municipal solid waste (MSW). Consequently, municipalities of different cities in India face various difficulties in MSW collection, treatment and disposal methodology. Inefficient or poorly managed MSW causes numerous troubles, including air pollution, soil fouling, contamination in drinking water and health hazard, and it also impacts socio-economic deterioration. MSWM technique selection is based on several criteria, which are generally imprecise, uncertain, and vague. This paper uses the cubic Pythagorean fuzzy number to comprise the fuzzy characteristics of the criteria value concerning the five alternatives (Thermochemical methods in MSW treatment and disposal). The best MSW treatment and disposal method is selected amongst the five alternatives under the novel multi-criteria group decision-making (MCGDM) approach, the cubic Pythagorean fuzzy EDAS (Evaluation based on Distance from Average Solution) in the Indian context. The weight information of the criteria has yet to be wholly known. A non-linear optimization scheme is proposed to determine the criteria weights that are partially known to maximize the generalized total distance measure between alternatives corresponding to all criteria. The present method is explained with a case study. Finally, a comparative analysis is drawn between the present and some existing methods, showing that the present method is consistent and robust enough to apply in practice.

Spatiotemporal patterns and drivers of carbon emissions from municipal solid waste treatment in China

Reducing carbon emissions from municipal solid waste (MSW) treatment is non-negligible for China to meet its “carbon peaking and carbon neutrality” targets. It is critical to objectively evaluate the spatiotemporal patterns and drivers of carbon emissions from MSW treatment. This study estimates the carbon emissions from MSW treatment across 30 Chinese provinces from 2011 to 2020. The joint approach LMDI-PDA model is further used to refine the impact of policy on carbon emission changes from technical and efficiency perspectives, while considering the socio-economic factors. The results showed that carbon emissions from MSW treatment grew significantly until peaking at 202.05Mt CO2e in 2017 and then stabilized, finally dropping to 165.10 Mt CO2e in 2020 due to the impact of COVID-19. Compared with the “12th Five-Year Plan” period, the MSW emissions intensity declined significantly during the “13th Five-Year Plan” period, indicating the effective implementation of waste emission control measures. Furthermore, the slowdown in the growth of national emissions was primarily driven by technological advances in waste treatment. Technical efficiency change effect, MSW generation intensity effect, economic scale effect, and population scale effect impeded national emissions decline. Since the performance of various drivers varied greatly in different provinces, a cluster analysis was conducted to provide policy recommendations in provinces with similar characteristics. Both the methods and results of this study can provide better decision-making support for national and provincial carbon emissions control policies targeting MSW treatment.

Municipal solid waste treatment complex in small towns. Case study: San Andrés de Machaca.

The project to conceptualize the Urban Solid Waste Treatment Complex in the town of San Andrés de Machaca, has been designed to give final disposal to common solid waste and hospital waste generated in the urban area and part of the rural area, in addition to taking advantage of organic waste through the generation of compost, additionally contemplates the recovery of part of the potentially recyclable materials, which will be carried out in a recycling plant that will be located inside the complex. The proposed and requested design is intended not as a final disposal site, but rather as a complex that integrates all the units in order to take advantage of solid waste, so that in the long term the common waste cell reduces the waste it receives. and thereby increase its useful life.