Solid Waste Treatment Technologies Research Articles

New insight into the spatio-temporal patterns of functional groups of hotspot inside the composting aggregates by synchrotron-based FTIR in hyperthermophilic composting

Hyperthermophilic composting (HTC) is a recently developed and highly promising organic fraction of municipal solid waste (OFMSW) treatment technology. Investigation of organic matter (OM) dynamics in compost particle is thus crucial for the understanding of humification of HTC process. Herein, this work aimed to study the chemical and structural changes of OM at the molecular level during HTC of OFMSW using EEM and SR-FTIR analyses. Additionally, two-dimensional correlation spectroscopy (2D-COS) was also utilized to probe and identify the changes in chemical constituents and functional groups of organic compounds on the surface of compost particles during different composting periods. Results show that SR-FTIR can detect fine-scale (~μm) changes in functional groups from the edges to the interior of compost particles during different composting periods by mapping the particles in situ. In the hyperthermophilic stage (day 9), the extracted μ-FTIR spectrum reveals a distinct boundary between anaerobic and aerobic regions within the compost particle, with a thickness of anaerobic zone (1460 cm−1) of approximately 30 μm inside the particle's core. This provides direct evidence of anaerobic trends at compost microscales level within compost particles. 2D-COS analysis indicated that organic functional groups gradually agglomerated in the order of 1330 > 2930 > 3320 > 1600 > 1030 > 895 cm−1 to the core skeleton of cellulose degradation residues, forming compost aggregates with well physicochemical properties. Overall, the first combination of SR-FTIR and EEM provides complementary explanations for the humification mechanism of HTC, potentially introducing a novel methodology for investigating the environmental behaviors and fates of various organic contaminants associated with OM during the in-situ composting biochemical process.

Prediction and Feed-In Tariffs of Municipal Solid Waste Generation in Beijing: Based on a GRA-BiLSTM Model

To cope with the increasing energy demand of people and solve the problem of a “Garbage Siege”, most cities have begun to adopt waste power generation (WTE). Compared to other WTE technologies, incineration has proven to be the most efficient technology for municipal solid waste (MSW) treatment. Therefore, to further explore the economic feasibility of MSW incineration plant construction, this study established a multi-factor prediction of MSW generation based on the GRA-BiLSTM model. By fully considering the relationship between the change in feed-in tariff (FIT) and the building of an incineration plant in Beijing, the economic feasibility of building an incineration plant is discussed based on the three scenarios set. The experimental results showed that (1) the combined model based on the GRA-BiLSTM showed good applicability for predicting MSW generation in Beijing, with MAE, MAPE, RMSE, and R2 values of 12.47, 5.97%, 18.5580, and 0.8950, respectively. (2) Based on the three scenarios set, the incineration power generation of Beijing MSW will show varying degrees of growth in 2022–2035. In order to meet future development, Beijing needs to build seven new incinerators, and the incineration rate should reach 100%. (3) According to setting different feed-in tariffs, based on the economic feasibility analysis, it is found that the feed-in tariff of MSW incineration for power generation in Beijing should be no less than $0.522/kWh. The government should encourage the construction of incineration plants and give policy support to enterprises that build incineration plants.

Energy, exergy and exergo-economic analysis of a novel HT-PEMFC based cogeneration system integrated with plasma gasification of food waste

Landfill and incineration of food waste would result in a significant waste of resources. Plasma gasification, as a novel solid waste treatment technology with cleaner product, is suitable for this perishable kitchen waste with high water and oil content. In present research, a food waste plasma gasification driven HT-PEMFC cogeneration system is proposed. Based on the established models, a comprehensive study is conducted from the perspective of energy, exergy and exergo-economy. Effects of key operational parameters on critical performance indicators are investigated. Results show that current density imposes an obvious effect on the cogeneration efficiency, this efficiency is obtained as 0.523–0.457 at low current density varying from 0.1 to 0.4 A/cm2. Exergy analysis results indicate that the plasma gasifier and the stack have the largest exergy destructions, accounting for 62.1 % and 32.2 % of the total, respectively. Gasification temperature has a great effect on the system exergy efficiency which is 0.603–0.384 when this temperature increases from 1000 K to 1300 K. Current density also has an obvious effect on the exergo-economic performance, the exergy cost per unit is obtained as 46.1–51.8 $/GJ when current density varies from 0.2 to 0.4 A/cm2. The optimization results are obtained as cogeneration efficiency of 0.4636, exergy efficiency of 0.6125 and exergy cost per unit of 24.58 $/GJ. This research provides a novel solution for substantial treatment of food waste, and guidelines for sustainable development of efficient and clean utilization technology of municipal solid waste.

Application of microbial agents in organic solid waste composting: a review.

The rapid growth of organic solid waste has recently exacerbated environmental pollution problems, and its improper treatment has led to the loss of a large number of biomass resources. Here, we expound the advantages of microbial agents composting compared with conventional organic solid waste treatment technology, and review the important role of microbial agents composting in organic solid waste composting from the aspects of screening and identification, optimization of conditions, mechanism of action, combination with other technologies and ultra-high-temperature and ultra-low-temperature microbial composting. We discuss the value of microorganisms with different growth conditions in organic solid waste composting, and put forward a seasonal multi-temperature composite microbial composting technology. Provide new ideas for the all-round treatment of microbial agents in organic solid waste in the future. © 2024 Society of Chemical Industry.

Whether biorefinery is a promising way to support waste source separation? From the life cycle perspective

Since the implementation of the waste separation policy, the disposal of source-separated food waste (FW) has been more strictly required. Traditional source-separated FW treatment technologies, such as anaerobic digestion (AD) and aerobic composting (AC), suffer from low resource utilization efficiency and poor economic benefits. It is one of the main limiting factors for the promotion of waste separation. Life cycle assessment (LCA) was conducted for five municipal solid waste (MSW) treatment technologies, compared their environmental impacts, and analyzed the impact of waste separation ratios to determine whether biorefinery is a promising way to support waste source separation. The results showed that black soldier fly (BSF) treatment had the lowest net global warming potential (GWP) of all technologies, reduced by 40.8 % relative to the non-source-separated treatment. Ethanol production had the second-lowest net environmental impact potential because bioethanol replaces fossil fuel to avoid the emission of pollutants from its combustion. When two biorefinery technologies with excellent efficiency to avoid environmental impact are used to treat source-separated FW, the increase in the percentage of waste separation will help reduce the environmental impact of MSW treatment. The application of biorefinery technologies is considered a viable option for source-separated FW treatment. AC should not be widely promoted because it showed the worst net environmental benefits, and waste separation will elevate the environmental impact of its treatment process.

Numerical Study of Resistance Loss and Erosive Wear during Pipe Transport of Paste Slurry

Cemented paste backfill (CPB) as a solid waste treatment technology that prepares tailings as aggregate into a highly concentrated slurry to be transported to the underground mining area, is now widely used in mines. However, the pipeline resistance loss and erosion wear during CPB slurry transportation considering the coupling effect of inlet velocities, viscosities, and particle sizes have not yet been well evaluated and analyzed. Hence, the CFD-based three-dimensional network simulation of CPB slurry flow in an L-shaped pipe at different combinations of the three parameters was developed using COMSOL Multiphysics software. The results showed that the pipe resistance loss was most affected by the inlet velocity and viscosity, with the minimum pipe resistance loss occurring at an inlet velocity of 1.5 m/s, a viscosity of 2.0 Pa·s, and a particle size of 150 μm. In particular, pipe erosion wear was severest at the bend and was positively correlated with inlet velocity and particle size, and negatively correlated with slurry viscosity, with maximum pipe erosion wear occurring at an inlet velocity of 3.5 m/s, a viscosity of 3.0 Pa·s, and a particle size of 2000 μm. The findings would be important for the design of the CPB pipeline transportation, which will improve the safety and economic level of a mine.

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

Development of Sustainability Assessment Criteria in Selection of Municipal Solid Waste Treatment Technology in Developing Countries: A Case of Ho Chi Minh City, Vietnam

Municipal solid waste (MSW) management is a significant problem for developing countries due to lack of sufficient infrastructure, poor management capacity, and low level of waste treatment technology. This study proposes three main groups of criteria, i.e., social, economic, and environmental, that can be used as an effective tool to assess the sustainability of MSW treatment technologies, considering Ho Chi Minh City, Vietnam as a case study. The sustainability assessment criteria consist of a list of indicators which consider potential waste treatment plants. The indicators and technologies then undertake a selection process from identifying assessment goals and key aspects to data collection and consultation of experts. The findings from the previous phase will be used to select the most preferred waste technology through AHP and normalization approaches. As a result, 12 selected indicators are as follows: investment cost, treatment cost, operation and maintenance costs, revenue/benefits, job creation, community consensus, support policy, community health, air pollution, water pollution, greenhouse gas emissions, and land quota. Among three MSW facilities selected, i.e., landfill, compost, and waste-to-energy incineration, waste-to-energy is determined as the best alternative solution for Ho Chi Minh City in a given context of approximate 70% of landfilling being applied. The selection process and indicators found can guide decision-makers and policy on selecting MSW treatment technologies in developing countries. Additionally, Ho Chi Minh City’s governors benefit from finding the most appropriate waste technology. A technology adoption roadmap and its implementation plan should be thought thoroughly to address challenges in MSW management in the city.

Comprehensive Evaluation of Hazardous Solid Waste Treatment and Disposal Technologies by a New Integrated AHP&MARCOS Approach

Hazardous waste management (HWM) deals with processing waste materials, and improper handling of this procedure might considerably harm human health and environment. It is crucial to employ the most appropriate treatment and disposal techniques while handling with waste materials as part of hazardous waste management so that potential problems can be minimized accordingly. Therefore, the weights of the criteria playing vital roles in solid waste management were determined by using AHP&MARCOS method, which is an integrated MCDM technique, and the most appropriate techniques to be employed in solid waste treatment and disposal were selected. The implementation took place in three phases; the first phase included brainstorming and literature review and the determination of the important criteria in the waste management (4 main and 12 sub-criteria) as well as the treatment (3) and disposal (7) methods to be employed; i.e, the alternatives. In addition, a decision-making group of 15 people was formed so that they could share their opinions based on their knowledge and experiences via the decision matrices while evaluating the alternatives according to the predetermined criteria. In the second phase, the decision matrices constructed based on the expert opinions were taken into consideration while determining weights/priorities of waste management criteria by employing AHP method. In the third phase, treatment and disposal methods were listed by using the decision matrices filled according to expert opinions, the weight values and the criteria. The criteria weights obtained by using AHP method revealed that “operation cost” was the criteria with the highest weight of importance while determining solid waste treatment/disposal methods. Similarly, among the obtained alternatives, the best solid waste treatment technique was found to be “physical treatment” and the best solid disposal technique “plasma arc”. The present study is different from similar studies in the literature since the selection of treatment and disposal method was performed separately for all hazardous solid wastes (healthcare waste, municipality solid waste, etc.) for the first time. Moreover, the obtained results were evaluated by undertaking comprehensive analyses (sensitivity and comparison). The findings obtained in the present study are expected to make valuable contributions to the literature.

Selection of plastic solid waste treatment technology based on cumulative prospect theory and fuzzy DEMATEL.

Under the global implementation of a low-carbon economy, the treatment of municipal plastic solid waste (PSW) has become an important task to be solved urgently. In the actual decision-making process of PSW treatment, the evaluation information is usually fuzzy, and the decision-makers (DMs) are bounded rational. For selecting the most appropriate PSW treatment technology, we propose a multi-criteria decision-making (MCDM) method based on cumulative prospect theory and fuzzy decision-making trail and evaluation laboratory (DEMATEL). Firstly, we construct the criteria system of PSW treatment that consists of 9 sub-criteria from the perspectives of environment, economy, society, and technology. Then, considering the interdependences and interactions between these evaluation criteria and allowing multiple stakeholders to participate in decision-making, we propose a fuzzy DEMATEL method to deal with the fuzziness of evaluation in the decision-making process and determine the weights of the evaluation criteria. Subsequently, taking into account the different opinions of different stakeholders and psychological factors such as risk preference and loss aversion of stakeholders, we aggregate the evaluation information of different stakeholders and develop the PSW treatment alternatives to rank the orders by using the proposed multi-actor cumulative prospect theory (CPT) method. We study seven alternative processes for PSW treatment by the developed model, including landfill, recycling, pyrolysis, incineration, and the combination of landfilling and recycling, landfill and incineration, and recycling and pyrolysis. According to the ranking results, we find the combination of recycling and incineration is the best treatment alternative. We take the seven PSW treatment technologies in Shanghai as the case study to verify the effectiveness and feasibility of the proposed method. Through the sensitivity analysis and comparison analysis with fuzzy similarity to ideal solution (FTOPSIS) method and an acronym in Portuguese of the interactive and multi-criteria decision-making (TODIM) method, we illustrate the effectiveness and superiority of the proposed method. This research provides significant references for the PSW treatment technology selection problems under uncertain environments and extends the methods in the decision-making field.

Comparison and selection of municipal solid waste treatment technologies in Tibet plateau area

The treatment of municipal solid waste has different impacts on the society, economy and environment of a region. It is extremely important to select a municipal solid waste disposal method suitable for the Tibetan Plateau. In the study, social, technical, economic, environmental and municipal solid waste characteristics are selected as comprehensive analysis indicators, and then combined with analytical hierarchy process and technique for order preference by similarity to an ideal solution methods for comprehensive analysis. The results show that the population size, population growth, population density and other indicators account for a large weight, and have a greater impact on the selection of municipal solid waste treatment methods. Through the final analysis, it is believed that the incineration treatment method is better than the landfill treatment method in the Tibetan plateau area.

Selection of a Suitable Waste to Energy Technology for Greater Beirut Area Using the Analytic Hierarchy Process

Waste to Energy (WtE) is becoming an interesting option for many countries as an effective waste management solution. The goal of this study is the selection of a suitable WtE technology for the treatment of municipal solid waste in Greater Beirut Area (GBA). In adopting a potential WtE technology for solid waste treatment in GBA, the protection of the environment and citizens health is mandatory, but it is also evident the pressing need for economically feasible new electrical energy sources. For a well and an efficient functioning of a WtE plant, an appropriate supply chain system of municipal solid waste should be guaranteed. The selection of a suitable WtE technology is a complex decision and to achieve the stated objective the Analytic Hierarchy Process (AHP) method was employed and experts in the waste management sector were consulted to formulate the model. AHP analysis was performed using SpiceLogic software. Results indicate that Composting is the best choice with a global score of 0.33, followed by Anaerobic Digestion which acquired 0.21 and Incineration ranked as the third preferred technology obtaining 0.14. A sensitivity analysis was conducted to ensure the results consistency, assessing the reliability of the experts’ judgments.

Exploring Key Components of Municipal Solid Waste in Prediction of Moisture Content in Different Functional Areas Using Artificial Neural Network

Moisture content is a very important parameter for municipal solid waste (MSW) treatment technology selection and design. However, the moisture content of MSW collected from different urban areas is influenced by its physical composition in these areas. The aim of this study was to analyze the key components of MSW for predicting moisture content in different functional areas via the development of an artificial neural network (ANN) model. The dataset used in this study was collected in Shanghai from 2007 to 2019. Considering the influence of functional areas, the model obtained the performance with MAE of 2.67, RMSE of 3.29, and R2 of 0.83, and an eight-fold cross validation showed acceptable results. The inter-quartile range (IQR) and isolation forest were compared to detect and remove outliers. In descending order, the moisture content was ranked as commercial/residential > office > cleaning areas. Based on a parameter exclusion method, kitchen, rubber, and plastic wastes show the greatest influence on moisture content in residential and commercial areas. In cleaning and office areas, paper, wood and bamboo waste products were the most important components. The determination of key components in different functional areas is of benefit for reducing the workload of moisture content estimation.

In-situ removal of odorous NH3 and H2S by loess modified with biologically stabilized leachate

The loess regions distribute widely in Northwestern China, North America and Eastern Europe. For these regions, landfill is a suitable technology for solid waste treatment. However, as a landfill cover material, loess is not very effective in controlling the emission of malodorous gases. The present study modified loess with biologically stabilized leachate, and investigated the capacities and mechanisms of the modified loess to remove odorous NH3 and H2S. The removal rates of NH3 and H2S at different acclimation time, targeted gas concentrations and temperatures were measured. It was found that the NH3 removal rate of the modified loess was up to 0.08 μmol/(g·hr), which was 1.8 times that of the virgin loess. The H2S removal rate of the modified loess was up to 1.74 μmol/(g·hr), which was 1.25 times that of the virgin loess. The half-meter loess layer modified by biologically stabilized leachate achieved nearly 100% removal of H2S. The improvement of NH3 and H2S removal ability was mainly due to the enrichment of relevant microorganisms. This work proposed a novel method for in-situ control of malodorous pollutants in landfills in the loess regions, and proved that the in-situ removal of NH3 and H2S using the loess modified with biologically stabilized leachate is feasible and cost-effective.

Characterization and comparison of gasification and incineration fly ashes generated from municipal solid waste in Singapore

Slagging-gasification has received increasing attention as a municipal solid waste treatment technology. Compared with incineration, slagging-gasification can produce valuable syngas and generates by-products that can be easier reusable in different applications in some cases. Among these by-products, the gasification fly ash (GFA) is the only hazardous solid residue to be landfilled. To explore its potential recycling methods and maximize its recycling efficiency, the detailed physicochemical properties of GFA are crucial. This study conducted a comprehensive characterization of six GFA samples and the results were compared with one incineration fly ash (IFA) sample and available data of IFA collected in Singapore in literature. X-ray fluorescence (XRF), and microwave acid digestion (MAD) followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectroscopy (ICP-MS) were carried out to determine the physicochemical composition of ashes. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were applied to identify their mineralogical composition. The hazard of the material was assessed through one-stage batch leaching tests. The results showed that the GFAs and IFA were both mainly composed of calcium compounds and chloride salts. However, GFA contained higher amounts of heavy metals especially lead (Pb) and zinc (Zn) than IFA. Zn contents in tested GFA samples were in a range of 1.4–3.0%, indicating the potential to recover Zn. The Ca(OH)2 content in GFA samples was up to 24.1%, which could be recovered as a low-grade lime. Based on the characteristics of GFA, a reusing method combining civil engineering utilization and resource recovery was suggested.

Energy and economic evaluation of MSW incineration and gasification in Brazil

Ever-increasing waste generation from the world population, along with the demand for renewable energy sources, are two topics gaining prominence in global conversations. Energy recovery of municipal solid wastes stands out as a possible solution for both problems. Thus, the present study aims to analyze the use of gasifiers and incinerators as technology for municipal solid waste treatment and energy generation from economic and energetic perspectives. The study was carried out in three municipalities in different regions of Brazil with distinct characteristics: Itajubá, Campinas and Campo Grande. The calculations were performed considering each city's waste production values and gravimetric composition. For each, two different waste flow scenarios were considered: the first adopted constant power and waste treatment values, while the second used values that varied year to year. The results obtained showed that the second scenario had greater energy potential than the first; however, its generation costs are higher, due to the greater flow of waste. Regarding the types of technology, gasification resulted in lower generation costs in Itajubá, while incineration was more attractive for Campinas and Campo Grande. This distinction can be explained by the different levels of organic matter in the cities involved. The use of both types of technology did not prove to be economically viable for any of the cities and conditions analyzed, thus demonstrating the need for government incentives for their viability.

Gas, Water and Solid Waste Treatment Technology

The increasing trends in gas pollution, water pollution, and solid waste pollution have an adverse impact on human health and ecological habitats [...]

Multi-criteria analysis of municipal solid waste treatment technologies to support decision-making in Kisumu, Kenya

The directive to close the dumpsite in Kisumu, Kenya has made the search for alternative solid waste treatment and disposal technologies urgent. The aim of this research is to support the decision-making process by analyzing multiple socioeconomic and environmental parameters of salient solid waste treatment options. We used multi-criteria analysis to assess and compare anaerobic digestion, sanitary landfill, bioreactor landfill, and incineration. Informed by field observations and interviews, the chosen assessment criteria were economic costs, electricity generation, GHG emissions, land footprint, air pollution, soil and water contamination, and compatibility with recycling efforts. A literature review yielded quantitative and qualitative data that supported the analysis and the ranking of solutions according to performance in each criterion. Our analysis shows that anaerobic digestion is a suitable solution for Kisumu, due to its reduced environmental impacts, production of electricity and fertilizer, suitability to treat the large organic waste stream generated in the city, and compatibility with independent recycling activities. Landfilling represents a cheap solution; however, previous failed initiatives indicate that finding available land close to main waste generators is a challenge. Incineration is costly and requires advanced air quality control equipment and high combustibility of incoming waste, which is not the case for Kisumu, where over 60% of waste stream is organic/wet. Our results and recommendations are targeted for the Kisumu case, but they can be relevant for researchers and policymakers elsewhere, especially in low- and middle-income cities facing similar challenges.

Hyperthermophilic Composting Technology for Organic Solid Waste Treatment: Recent Research Advances and Trends

Organic solid waste is considered a renewable resource that can be converted by various technologies into valuable products. Conventional thermophilic composting (TC), a well-studied and mature technology, can be applied to organic solid waste treatment to achieve waste reduction, mineralization, and humification simultaneously. However, poor efficiency, a long processing period, as well as low compost quality have always limited its wide application. In order to overcome these shortages, hyperthermophilic composting (HTC) has been recently put forward. This paper reviews the basic principle, process flow, operation parameters, research advances, and application status of HTC. Compared with the TC process, the shorter composting period and higher temperature and treatment efficiency, as well as more desirable compost quality, can be achieved during HTC by inoculating the waste with hyperthermophilic microbes. Additionally, HTC can reduce greenhouse gas emission, increase the removal rate of microplastics and antibiotic residues, and achieve in-situ remediation of heavy metal-polluted soils, which greatly improve its application potential for organic solid waste treatment. This paper also proposes the limitations and future prospects of HTC technology for a wider application. As a result, this review advances our understanding of the HTC process, which promotes its further investigation and application.

Research progress of plasma gasification technology for solid waste treatment

The rapid development of social economy leads the output of solid waste to increase rapidly. The traditional treatment methods, such as landfilling, incineration and composting, are not only inefficient, but also have many limitations, such as secondary pollution and waste of resources. Therefore, it is urgent to explore new solid waste treatment technology. Due to its high efficiency, environmental protection and high energy conversion, the plasma gasification technology has been applied to the harmless treatment of solid waste. This article introduces the background and significance of plasma gasification technology in solid waste treatment, and summarizes the application of plasma gasification technology to different solid waste treatments, the technical level and research progress of plasma gasification of solid waste in the world are described in detail, and the existing problems in the current application of plasma gasification of solid waste are emphatically analyzed. It is pointed out that plasma gasification technology is an effective way to treat solid waste.