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The leaves of 'khat' (Catha edulis Forsk), a plant widely grown in Ethiopia are chewed by local people for their stimulant action. Its branches and part of the leaves are thrown as solid waste. The objectives of this study was to characterize fuel briquette made from this waste disposed in Hawassa city, Ethiopia. First, charcoal fines were prepared from the khat branches and the leaves. The charcoal fines were then mixed with 20% of clay as a binder. It was followed by molding the mixture in a press machine to produce Branch Charcoal Briquette (BCB) and Leaves Charcoal Briquette (LCB). The experimental results showed the Carbonized Branch Briquette Charcoal (CBBC) has an average calorific values of 19,890 kJ/kg and its other performance parameters are also within the acceptable range. Hence, the city's khat residue can be easily processed into CBBC to substitute yearly 480 ton of charcoal and reduce roughly 1,020 tons of carbon dioxide emission to the environment. The Carbonized Leaves Briquette Charcoal (CLBC) did not gave satisfactory results. Hence, it had been recommended to be studied further., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: All authors certifies that the work is original, has never been published, and is not presently being considered for publication anywhere else. We confirm that each of the mentioned authors has read and approved the work, and that no other individuals have met the requirements to be included as authors. We also reaffirm that we have all endorsed the authors’ indicated order in the work. We are aware that the only point of contact for the Editorial process is the Corresponding Author. He is in charge of keeping the other authors informed about their work, submitting edits, and approving proofs in the end., (Copyright: © 2024 Gebreyes et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

This study is an inventory analysis and environmental life cycle assessment of hotel food waste management that seeks to inform efforts towards the development of bio circular economy in Zimbabwe. An audit of food waste generation and an inventory analysis of the prevailing food waste management practices at three selected hotels was undertaken. The greenhouse gas emissions from the prevailing disposal of food waste at dumpsites and the proposed biological treatment of food waste were evaluated using the Tier 1 FOD method and Tier 1 method of biological treatment using the 2019 refined 2006 Intergovernmental Panel on Climate Change guidelines. Environmental life cycle assessment was also conducted for the open dumping, composting, and anaerobic digestion. The average food waste generation within the Zimbabwean hospitality industry was estimated at 1.63 kg/guest/day, with a minimum and maximum of 1.01 and 2.25 kg/guest/day, respectively. Source-separated food waste is currently being collected indiscriminately by municipal waste collection trucks for final disposal at the official landfills or dumpsites. This calls for the need for an offtake system of the source-separated food waste in the form of composting or anaerobic digestion. Study results showed that the disposal of food waste at solid waste disposal sites contributes to the highest greenhouse gas emissions, followed by composting with a 75% reduction in greenhouse emissions. Anaerobic digestion brings about a maximum reduction in greenhouse emissions of 97%. Environmental life cycle assessment results also show that anaerobic digestion is the best method leading to net negative environmental impacts., Competing Interests: Declarations Competing interest The authors declare no competing interests., (© 2024. The Author(s).)

Leachate from municipal solid waste landfills poses a significant threat to aquatic ecosystems due to poor management practices. This study evaluated thirty leachate samples from Iranian metropolises using the Leachate Pollution Index (LPI). Various parameters, including BOD₅, COD, TDS, pH, EC, heavy metals, turbidity, PAHs, phthalates, and humic acid, were analysed. The BOD₅ levels ranged from 350 to 20,000 mg/L, and the COD levels ranged from 2,000 to 90,000 mg/L. The TDS content varied between 14.7 and 67 g/L, while the turbidity ranged from 15 to 186 NTU. Heavy metals were present but within standard limits. The phthalate concentrations ranged from 6 to 150.8 mg/L, and the humic acid concentrations ranged from 135 to 2,200 mg/L. Naphthalene was the most frequent hydrocarbon detected. The LPIs were less than 30 for all the samples, with the highest in Ahvaz and the lowest in the treated samples from Tehran. This study highlights the presence of persistent organic and hazardous contaminants in Iran's municipal landfills, emphasizing the need for effective leachate treatment and improved waste management practices. Enhanced final disposal methods, increased waste recovery, and improved solid residue separation are crucial for preventing further leachate production and environmental contamination., (© 2024. The Author(s).)

To maximize energy recovery in waste-to-energy (WTE) systems, the High Heating Value (HHV) of municipal solid waste (MSW) must be accurately estimated. To forecast the HHV of MSW, this study proposes a unique method that combines an Artificial Neural Network (ANN) model with Latin Hypercube Sampling (LHS), with a focus on Solan City, Himachal Pradesh, India. In the present study, the elemental characteristics of waste have been used to deal with uncertainty and to find the suitable parameters responsible for the HHV of the MSW. Initially, Latin Hypercube Sampling (LHS) has been used to deal with uncertainty in the elemental composition of MSW, which includes carbon (C), hydrogen (H), nitrogen (N), sulfur (S), and oxygen (O) content. This elemental composition has been used as input parameters to the ANN model for predicting the HHV of MSW. The network 5-28-5-1 offered a minimum MAPE value of 2.18%, MSE, RMSE and R 2 values are 0.012, 0.107 and 0.767, respectively. Thereafter, a synaptic weight approach was used to find the most significant parameters responsible for HHV in MSW. It was observed that carbon is the most suitable parameter for HHV of MSW. By dealing with the uncertainty in MSW characteristics, the integration of LHS strengthens the robustness of the model. The results offer an accurate and economical approach for HHV estimation, which will be useful for improving the MSW management and WTE conversion procedures., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Effective solid waste management is a critical environmental challenge, particularly in rapidly growing Global South countries like Nigeria. This issue is exacerbated by burgeoning populations, lax waste regulations, and the widespread practice of open dumping. The deterioration of soil quality and alteration of water quality are major consequences of open waste dumping, posing significant environmental and public health risks. This study aims to assess the environmental risk and pollution status of soil and water resources near major dumpsites in Lagos. It aims to offer insights that can inform targeted interventions and policy measures not only in Lagos but also in comparable urban settings worldwide. Results indicated that important soil parameters, including TN (11.89-13.83 mg/kg), pH (6.45-7.35), sulfate (36.71-39.49 mg/kg), phosphate (9.31-14.39 mg/kg), and electrical conductivity (342-566 µS/cm), were significantly affected by the dumpsites. Additionally, concentrations of heavy metals varied, with some exceeding permissible limits set by international standards, highlighting the environmental challenges posed by improper waste disposal in urban settings like Lagos. The analyzed parameters for water were mostly within acceptable limits, indicating a lesser impact of the waste dump on water resources. Water samples from boreholes and hand-dug wells near three dumpsites showed that pH, TDS, and heavy metal concentrations were mostly within WHO limits, with borehole water deemed safe for drinking and hand-dug wells suitable for cleaning. To alleviate the environmental impacts of open dumpsites, it is recommended to implement effective waste segregation, recycling programs, controlled landfilling, and investment in waste treatment technologies, along with regular water quality monitoring to prevent further pollution and protect public health. While these measures offer opportunities, they also face significant challenges due to financial and land constraints. Therefore, strong public awareness, infrastructure investment, and government commitment are essential, along with coordinated efforts among the government, private sector, and communities., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Co-disposal of hexabromocyclododecane (HBCD)-containing waste during municipal solid waste incineration (MSWI) was conducted, achieving a destruction efficiency exceeding 99.999%. Simultaneous determination of HBCD, polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) at multiple stages of a MSWI plant was performed. This aimed to clarify their concentration and congener variations along the flue, with the goal of elucidating their formation mechanisms and control. This study confirmed that HBCD was present in daily MSW, and that PBDEs and PBDD/Fs can be unintentionally produced. The average mass emission factors of HBCD, PBDEs, and PBDD/Fs from stack gas were 6.4 ± 5.0, 98.8 ± 4.6, and 2.8 ± 1.7 μg t -1 , respectively. HBCD and PBDEs were much higher in slag, raising concerns about the secondary release of brominated pollutants during the reprocessing or reuse of incinerator slag. The concentrations of PBDEs and PBDD/Fs increased after the air pollution control devices, largely due to the "memory effect", with regenerated PBDD/Fs being mainly high-brominated homologs. The disposal of HBCD increased PBDEs concentration and altered PBDD/F homolog distribution. Possible formation pathways of PBDEs and PBDD/Fs from HBCD were proposed. HBCD could degraded into brominated short-chain hydrocarbons and aromatic fragments, which may promote the formation of PBDEs and PBDD/Fs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Municipal solid waste (MSW) management is a major concern for Bangladesh, given its high population density and increasing waste production rate. Conventional waste management methods, such as landfilling, result in high carbon emissions for the environment. With over 70% of MSW being organic, hydrothermal carbonization (HTC) has emerged as a promising technology for recovering energy and nutrients from such heterogeneous waste streams. This study aimed to compare the environmental effects of HTC coupled with electricity generation (HTC-EG) from MSW with traditional landfilling using life cycle assessment in the context of Bangladesh. The HTC-EG scenario showed lower environmental impacts in three out of five impact categories, specifically reducing climate change, freshwater ecotoxicity, and photochemical ozone formation. For a functional unit of 6000-ton MSW, HTC-EG reduces the climate change impact by 7.7 × 10 6  kg CO 2 eq. Additionally, HTC-EG has 46.77% less impact on freshwater ecotoxicity compared to landfilling and reduces the photochemical ozone formation impact by 1.86 × 10 4 NMVOC eq. However, the HTC-EG scenario leads to increased particulate matter formation and marine water eutrophication due to SO 2 , SO 3 , and PM2.5 emissions during hydrochar combustion and nitrate release from the liquid stream of the HTC reactor, respectively. Addressing these challenges through appropriate post-processing of flue gas from hydrochar combustion and HTC liquid streams could make HTC-EG a viable alternative to landfilling for MSW management in Bangladesh., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Sorting out plastic waste (PW) from municipal solid waste (MSW) by material type is crucial for reutilization and pollution reduction. However, current automatic separation methods are costly and inefficient, necessitating an advanced sorting process to ensure high feedstock purity. This study introduces a Swin Transformer-based model for effectively detecting PW in real-world MSW streams, leveraging both morphological and material properties. And, a dataset comprising 3560 optical images and infrared spectra data was created to support this task. This vision-based system can localize and classify PW into five categories: polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polystyrene (PS). Performance evaluations reveal an accuracy rate of 99.75% and a mean Average Precision (mAP 50 ) exceeding 91%. Compared to popular convolutional neural network (CNN)-based models, this well-trained Swin Transformer-based model offers enhanced convenience and performance in five-category PW detection task, maintaining a mAP 50 over 80% in the real-life deployment. The model's effectiveness is further supported by visualization of detection results on MSW streams and principal component analysis of classification scores. These results demonstrate the system's significant effectiveness in both lab-scale and real-life conditions, aligning with global regulations and strategies that promote innovative technologies for plastic recycling, thereby contributing to the development of a sustainable circular economy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The biological stability of solid waste is one of the main problems related to the environmental impact of landfills and their long-term emission potential. Current European legislation (European Landfill Directive, EC/99/31) introduced the need to reduce biodegradable organic compounds deposited in landfills; however, it set neither official parameters nor methods to define the stability of such a waste. In Spain, biodegradability is generally evaluated using the biological oxygen demand/chemical oxygen demand (BOD 5 /COD) ratio, measuring it on the leachate, thus not considering the non-soluble fraction and therefore creating false negatives. To solve this problem, the biodegradability of hazardous industrial waste has been determined by measuring its respirometric activity (AT 4 ). Our results show that the measure of the AT 4 is independent of the enrichment with a microbial inoculum, and a sample size no higher than 20 g could be a reasonable value for a sensitive biodegradability determination. The highest respirometric index is obtained in waste with pH values between 6.5 and 10.5. Furthermore, respirometric biodegradability values are independent of traditional parameters of organic matter characterization such as BOD 5 /COD ratio, volatile content, and total and dissolved organic carbon. Consequently, the AT 4 parameter provides new information on the composition and stability of organic matter in hazardous industrial waste. Its incorporation into pre-disposal waste characterization protocols allows to identify waste that exceeds recommended biodegradability thresholds. This approach ensures that only waste meeting specified biodegradability standards is deposited, avoiding landfill emissions and related environmental impacts, and thereby improving the overall effectiveness and sustainability of waste management practices., (© 2024 The Author(s). Journal of Environmental Quality published by Wiley Periodicals LLC on behalf of American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.)

Municipal solid waste (MSW) is a major anthropogenic contributor to climate change due to the substantial quantities of greenhouse gas (GHG) emitted by landfills and incineration. Circular waste management has shown promise in reducing GHG emissions; however, it is still in its early stages and requires further optimization. In this study, support vector machine models were developed to determine the compositional dynamics of MSW, which were then integrated to examine the interactions among composition, disposal routes, and GHG emissions. The results from analyzing large-scale transitions from traditional to circular waste management practices showed that GHG mitigation potential will be significantly enhanced as the coverage of circular waste management increases from 35% in 2025 to 100% in 2035 in China. However, these reductions will eventually decrease as waste quantities decline in response to population shrinkage. The results reveal both the GHG mitigation potential and limitations of the circular waste management mode, assisting policymakers and researchers in maximizing its mitigation potential., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Plastic waste has become a major contributor to global environmental pollution. Some of the environmental impacts of plastic waste include littering, the formation of plastic debris in oceans and the contamination of freshwater and terrestrial habitats. Policymakers face great challenges in mitigating plastic waste. Indonesia is considered the second largest contributor of plastic waste in the world. However, existing policies have not addressed this issue. Policies, such as bans on single-use plastic bags and fees on plastic bags, have recently been implemented in some pilot cities, but the results remain unclear. Thus, this study proposes feasible policies to mitigate plastic waste in Indonesia using system dynamics. Specifically, this study seeks to develop a dynamic model of plastic waste mitigation and to propose a policy scenario for plastic waste mitigation. The proposed policies consist of a plastic bag ban, a plastic bag fee, a recycling centre and extended producer responsibility (EPR). The analysis demonstrates that an effective mixed policy instrument for reducing plastic waste depends on the plastic waste type. Regarding plastic bottles, the effective mixed policy is a combination of a recycling centre and EPR. For plastic bags, the effective mixed policies include the following combinations: a plastic bag fee and plastic bag ban, a plastic bag fee and recycling centre and a plastic bag ban and recycling centre., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

To evaluate the potential of compost based on municipal solid waste (MSW) and 20% legume pruning under a pyrolysis process, generated products, including solids (biochar), liquids (bio-oil), and gases (non-condensable gases), through experimentation in a pilot plant with a fluidized bed reactor at 450°C and gas chromatography/mass spectrometry have been analysed. In addition, the compost kinetic behaviour by thermogravimetric analysis (TGA), using the Flynn-Wall-Ozawa (FWO) method, has been investigated. Four different reaction zones, associated with lignocellulosic materials (hemicellulose, cellulose, and lignin) with a first step for water evaporation, in TGA curve have been observed. A biochar with low stability and aromaticity, considering high and low O/C and H/C ratios, respectively, has been obtained. The obtained pyrolytic liquids contain a high concentration of phenolic compounds because of a significant presence of lignins and other high molecular weight compounds in the original material. Moreover, the generated non-condensable gases consist mainly of short-chain compounds, such as alcohols, aldehydes, and alkenes produced from hemicellulose, cellulose, and proteins., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) has shown to be a viable alternative since it allows energy recovery in the form of methane and generates a residue (digestate) that can be applied effectively as a soil improver or fertiliser. The potential for methane production and the digestates' characteristics depend on the substrate characteristics and the process variables such as temperature, solids retention time, and organic load. This study dealt with OFMSW anaerobic digestion under different organic loading rates and temperatures and the characteristics of the resulting digestates. Three semi-continuous reactors were operated at 20, 35, and 55°C and fed daily with ground, fresh OFMSW from Mexico City. The inoculum was temperature-adapted UASB granular sludge. The main results indicate that the anaerobic digestion was adequate, as the pH values were slightly alkaline, which is sufficient for methanization, and the alkalinity was not a limiting factor. Potassium and PO 4 -P increased with the organic load, and Kjeldahl nitrogen decreased. At 20°C, total organic carbon (TOC) increased substantially with the organic load; at 35°C, it remained without significant changes; and at 55°C, TOC slightly decreased with the organic load. The C/N ratio changed accordingly to TOC variations. At 20°C, the residual biogas potential increased with the organic load; at 35 and 55°C, it decreased with increasing organic load; the residual biogas potential increased with residual fatty acids concentrations. To comply with international standards for agricultural use, the digestates need only dewatering and supplementing with PO 4 -P.

This study is a critical review of municipal solid waste (MSW) hydraulic conductivity that includes investigation of the influence of vertical stress, dry unit weight and degradation. A total of 56 studies were compiled that included laboratory-, pilot- and landfill-scale hydraulic conductivity experiments. Compacting waste and increasing vertical stress reduce MSW hydraulic conductivity via reshaping the pore networks throughout the waste matrix, reducing the void ratio and increasing tortuosity. However, the magnitude of reduction in hydraulic conductivity is dependent on stress, waste composition and decomposition. Solid waste decomposition can have opposing effects on hydraulic conductivity. Some studies have indicated that an increase in MSW decomposition results in particle size reduction and settlement that reduces the void ratio and decreases hydraulic conductivity. Conversely, some studies indicate that waste decomposition reduces the solid mass, which increases the void ratio and creates larger flow paths that increase hydraulic conductivity. The data compilation, observations and key findings from this study are beneficial for solid waste practitioners to improve design, analysis and operation of MSW landfills., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Discharge from unrestricted tobacco products with filters (TPF) causes environmental damage. To reduce TPF litter quantities, Directive (EU) 2019/904 requires TPF producers to proportionally contribute to the costs of discarding their products in public waste collection systems, including litter waste ones. An appropriate output-based cost model requires assessing TPF quantities in relevant waste streams. Currently, there is no comprehensive data available on TPF quantities in municipal solid waste (MSW). Therefore, a case study was conducted to quantify TPF in MSW. This study aimed to determine TPF quantities (1) in residual waste from four German district types and (2) in waste from public collection systems for three settlement structures within Trier City. Relevant waste streams from public collection systems, namely waste from public waste receptacles, street-cleaning waste and sinkhole residues, were identified. For both sampling campaigns, consideration was given to extrapolating the results to a larger scale. The results showed that the average specific TPF quantities in residual waste were 277.7, 271.8, 193.3 and 204.5 gi - 1 a - 1 in the selected city district, urban district, densely populated rural district and sparsely populated rural district, respectively. Extrapolation of these results to Germany yielded a specific TPF quantity in residual waste of 250.3 gi -1 a -1 . The average specific TPF quantities in waste from public waste receptacles, street-cleaning waste and sinkhole residues were 12.2, 47.4 and 9.9 gi -1 a - 1 , respectively. The results could contribute to cost model development based on Directive (EU) 2019/904., Competing Interests: Declaration of conflicting interestsThe authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: This publication was prepared using data from contract research. pbo was commissioned to carry out an open-ended and objective scientific study on the subject of ‘Tobacco filters in municipal waste’ based on the guidelines of scientific practice. The contract research was commissioned by the Association of the Tobacco Industry and Novelty Products (Bundesverband der Tabakwirtschaft und neuartiger Erzeugnisse (BVTE)), the German Cigarette Association (Deutscher Zigarettenverband (DZV)), Philip Morris GmbH (PMG), the Association of the Cigarette Paper Processing Industry (Verband der Zigarettenpapier verarbeitenden Industrie (VZI)) and the Association of the Cigar Industry (Bundesverband der Zigarrenindustrie (BdZ)) to the Institute for Tobacco Research (Institut für Tabakforschung GmbH (IfT)) as project sponsor. In this context, pbo was commissioned by the Institute for Tobacco Research (Institut für Tabakforschung GmbH (IfT)). The Chair of Anthropogenic Material Cycles (ANTS) was commissioned via a subcontract from PBO.

The present study assessed the impact of municipal solid waste dump on the degradation of soil around Orji dump site. A total of 15 soil samples were collected for this study. Twelve soil samples were collected around the dump site at 0 m, 10 m, and 20 m distance and three from Imo State University (IMSU) research farm as control. The samples were collected from the east, west, north, and south of the dump site. The samples were subjected to laboratory analyses. The mean results obtained indicate that the values of the dump site soil parameters analyzed ranged from 86.67 to 89.00% (sand), 4.33 to 5.67% (silt), 7.00 to 7.67% (clay), 6.80 to 7.50 (pH), 4.33 to 7.00 dS m -1 electric conductivity (EC), 0.0028 to 0.0045 mg kg -1 (salinity), 2.36 to 3.76% soil organic matter (SOM), 24.13 to 38.93 cmolc kg -1 cation exchange capacity (CEC), 4.50 to 9.57 cmolc kg -1 calcium (Ca), and 1.0 to 2.25 cmolc kg -1 magnesium (Mg). At the control, mean values were 81.24% (sand), 6.39% (silt), 12.45% (clay), 5.69 (pH), 0.47 dS m -1 (EC), 0.0005 mg kg -1 (salinity), 1.99% (SOM), 5.08 cmolc kg -1 (CEC), 2.17 cmolc kg -1 (Ca), and 1.67 cmolc kg -1 (Mg). These values showed substantial enrichment. Correlations indicate that EC, salinity, and CEC majorly determined the availability of most of the parameters analyzed. Soil degradation index (SDI) was used to determine degradation around the dump site. It ranged from 2.546.61% (0 m) to 1573.50% (10 m) and 1.603.73% (20 m). Thus, distance affected the rate of soil degradation in all directions away from the dump site., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Food-waste solid residue is the remaining solid after food waste treatment, with high yield, high solid content, high protein and fiber content. Effective pretreatment is necessary to improve the efficiency of hydrolysis and acidification for anaerobic digestion of food-waste solid residue. In this study, fluorescence spectroscopy coupled with parallel factor analysis were used to insight into the mechanism of food-waste solid residue during three pretreatments (alkali, thermal and alkali-thermal). Pretreatments increased the solubility of lignocellulosic substrate and destroyed structure of starch, while lignocellulosic analogs were effectively cracked, changing the composition and improving the degradability. Soluble chemical oxygen demand, soluble protein and soluble polysaccharide concentrations were increased by 144.60%, 350.57% and 138.72% after pretreatment under the condition of 120 °C + 2% CaO, respectively. Three-dimensional fluorescence spectra showed the region of maximum fluorescence intensity under alkali-thermal pretreatments, indicating chemical bonds (such as OC-C) were easier broken and the solubility of organic substances were increased. Three main fluorescence components were obtained by parallel factor analysis, which were humic acid-like, lignocellulose-like and protein-like, respectively, while the lignocellulose-like had the maximum Fmax value. The fluorescence intensity of samples under alkali-thermal pretreatment varied in the range from 59.48 × 10 5 to 13.18 × 10 6 , which was an increase of 174.27%-507.74% over the control (21.68 × 10 5 ), indicating that alkali-thermal pretreatment observably accelerated the breaking of chemical bonds, and thus promoted the dissolution of organic matter. This study deeply revealed the mechanism of alkali-thermal pretreatment of food-waste solid residue, which is of great significance for efficient resource utilization of food waste and food-waste solid residue., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Legacy waste dumpsites have been a significant environmental concern in India for many years. These dumpsites are characterized by the uncontrolled disposal of Municipal Solid Waste (MSW) and have led to various types of pollution and disease outbreaks. As India faces the challenges of rapid urbanization and increased waste generation and with over 3000 legacy waste dumpsites in the country, the need to address these legacy waste dumpsites has become paramount. As we continue to struggle extensively for waste management as well as space, landfill mining has been recognized as a promising way of recovering resources in our country by employing various technological and engineering advancements to extract valuable materials and energy from legacy waste streams. Unlike existing waste management approaches, this review explores the application of a novel Recovery Potential Index (RPI) for legacy waste dumpsites in India, which evaluates the feasibility of waste treatment facilities based on waste compositions and recovered material quantities. Depending on the RPI, recovered fine fractions can be sold as city compost or used as fill material, while recyclable, combustible, and inert fractions could be directed towards appropriate recycling or landfill uses. Unscientific and uncontrolled landfill mining practices could lead to unanticipated impacts on the nearby environment in the form of heavy contamination, thereby presenting this practice as a challenge in addition to the immense opportunities it provides., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The incineration of municipal solid waste (MSW) produces byproducts known as MSW incineration (MSWI) ash. The reuse of MSWI ash as a construction material prevails in several areas of the world, namely Europe and Asia, however, reuse in the United States (US) lags due to regulatory requirements for disposal practices. Developing a recycling program for MSWI ash provides an alternative end-of-life disposal scenario for material currently landfilled and supplements the reliability of mining of natural aggregates. This study provides a programmatic review of the past decade of challenges and opportunities a local government in the US has experienced to implement a recycling program for their MSWI bottom ash (BA) as a construction aggregate in road materials, such as hot mix asphalt, concrete pavement, and road base. The regulatory and practical challenges in the U.S. are presented, including meeting mechanical and environmental performance requirements (e.g., strength and leaching-to-groundwater). The novel approach to overcoming these challenges include blending MSWIBA from two facilities with common aggregates, creating suitable construction materials. Interfacing with local and state agencies, such as the Department of Environmental Protection and Transportation resulted in additional testing to establish the MSWIBA as a beneficial use material and obtain essential approvals for advancing reuse opportunities. This paper synthesizes available data regarding the challenges, opportunities, and implementation of this recycling program by reviewing the experiences of an MSWI facility in the US to provide fundamental guidance to those considering similar applications. Implications: The reuse of municipal solid waste incinerator bottom ash (MSWIBA) lags in the United States (US) due to regulatory limitations and lack of precedence. This manuscript details the steps of a local government in the US to establishing a novel recycling program for their MSWIBA, including performance evaluation, regulatory interfacing, and outreach. This critical review provides a comprehensive document containing appropriate considerations required to implement similar MSWIBA recycling programs in the US and offers lawmakers, policymakers, and MSWI operators knowledge regarding opportunities and challenges associated with pursuing this avenue.

The municipal solid waste (MSW) management is significantly contributing to global greenhouse gas (GHG) emissions. Analyzing the emission pattern of GHGs from MSW is essential for formulating appropriate carbon mitigation policies. Based on IPCC Models, GHG emissions from MSW were calculated in Chinese provinces from 2004 to 2021 by landfilling and incineration operations, separately. Landfilling and incineration generated approximately 1271 MtCO 2 -eq and 198 MtCO 2 -eq from 2004 to 2021, respectively. GHG emissions from landfilling increased from 2004 to 2020 and declined in 2021, while GHG emissions from incineration demonstrated an increasing trend with three distinct growth stages. A panel regression model was then employed to identify the key factors influencing GHG emissions. GDP and population are positively related to GHG emissions from landfills, while PCCE is negatively related to GHG emissions from landfills. GDP and PCCE have a positive impact on GHG emissions from incineration, while population showed no significant impact. Multi-expression programming was used to develop an explicit model, forecasting GHG emissions from MSW by 2030. From 2022 to 2024, GHG emissions from landfills will quickly decrease, while GHG emissions from incineration will rapidly increase. Subsequently, the GHG emission rate of incineration will slow down, and GHGs from landfilling will slowly decrease due to no MSW for landfill disposal. The methods and results provide insightful information for policy-makers and waste management sector., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Numbers do matter; the Intergovernmental Panel on Climate Change (IPCC)'s 2010 data that the waste sector is responsible for just 3% of global greenhouse gas (GHG) emissions has led to the misperception that solid waste management (SWM) has little to contribute to climate mitigation. Global efforts to control methane emissions and divert organic waste from landfills had already reduced direct emissions. But end-of-pipe SWM has also been evolving into more circular waste and resource management, with indirect GHG savings from the 3Rs (reduce, reuse, recycle) which IPCC accounts for elsewhere in the economy. The evidence compiled here on both direct emissions and indirect savings demonstrates with high confidence that better waste and resource management can make a significant contribution to climate mitigation, and must form a core part of every country's nationally determined contribution. Even the most advanced countries can still achieve much from the 3Rs. In the Global South, the challenge of extending waste collection to all and stopping open dumping and burning (sustainable development goal 11.6.1), essential to improve public health, can be turned into a huge opportunity. Moving early to divert waste from landfill by separation at source and collecting clean organic and dry recycling fractions, will mitigate global GHG emissions, slash ocean plastics and create decent livelihoods. But this can only happen with targeted climate, plastics and extended producer responsibility finance; and help to local communities to help themselves., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

This study tackles the growing global concern about municipal waste management, particularly in cities like the Grand Guayaquil Metropolitan Area (GGA). Through realistic field studies on in situ household waste generation and geographic information system (GIS) tools, this work offers a framework to predict the quantities and types of recyclable household waste for any metropolitan area in Latin America. Over 4 weeks, students collected, sorted and weighed recyclable waste types, including plastic, paper, metal, glass and fabric, from 776 sampled household of the GGA. ArcGIS survey tool identified household locations and allowed to survey different socio-demographic features. With the help of ArcGIS interpolation method, the total household waste generation for GGA was predicted, and the classification of the different types of recyclable waste was also spatially distributed for the study area. The report identified notable trends in plastic waste, specifically polyethylene terephthalate waste's steady prevalence and 42% growth rate, emphasizing the importance of enhanced recycling techniques. Spatial density maps showed a heterogeneous waste distribution across the GGA, emphasizing locations with higher waste output. This study demonstrates that improving recyclable waste collection can be accomplished with a moderately cheap expenditure by collaborating with academia to overcome knowledge gaps. This strategy provides opportunities to mitigate the environmental impacts of poor waste management., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The optimization of alternative materials in concrete production continues to garner considerable attention in order to meet sustainability goals and supplement natural materials. Portland limestone cement (PLC) and municipal solid waste incineration (MSWI) bottom ash (BA) have been proposed separately as green cement and coarse aggregate supplement in low-strength concrete production, creating sustainable products and alternative disposal scenario for a waste material. This study discusses the impact of advanced ash processing techniques on aggregates and presents the performance of concrete incorporating both of these products with PLC for the first time. Two sources of MSWI BA were investigated, one as-produced (TMR) and one processed with novel advanced metals recovery (AMR). The AMR process reduced total Al content in ash compared to TMR (20,500 vs 17,000 mg/kg), though not aluminum oxide content, as the AMR process targets metallic aluminum. A composition study on both aggregates supports a reduction in ferrous and non-ferrous metals following the AMR process. All control and test mixes met 28-day compressive strength requirements (17 Mpa). Both AMR and TMR MSWI BA-amended concretes yielded compressive strengths below control specimens (no ash) ranging from 17 to 23 MPa, with little to no difference observed dependent on MSWI BA processing. The life-cycle discussion supports benefits deriving from supplementing naturally mined materials and recovering ferrous and nonferrous metals with the AMR process., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Timothy G. Townsend, Christopher C. Ferraro, Kate D. Weiksnar, Ethan J. Marks, Margaret J. Deaderick, Isabella Mejia-Ruiz report financial support was provided by Solid Waste Authority of Palm Beach County. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Municipal solid waste (MSW) management is a critical concern in megacities that depend heavily on external material and energy inputs but lack space for waste disposal. MSW treatment is a significant contributor to carbon emissions. The implementation of source classification improved the overall MSW management system and enhanced resource recovery from MSW. However, the precise contribution of source classification to carbon emissions reduction remains unclear. This study aimed to analyze the carbon emissions evolution in the MSW management of Shenzhen, a prototypical megacity in China, using data from 2006 to 2020 and employing carbon footprint assessment methodologies. The results demonstrated that source classification reduced the carbon emissions from 0.19-0.25 to 0.14-0.18 t CO 2 -eq/t MSW when considering the contribution of the urban environmental sanitation management department. The entire MSW management system becomes a carbon sink when considering recyclables collected by commercial enterprises. Although the source classification complicated the collection and transportation of MSW, the carbon offset effect of recycling food waste and recyclables was more significant than that of carbon emissions from collection and transport. Moreover, the landfill gas recovery rate critically influenced the carbon emissions of landfill-based MSW management systems. In contrast, the recovery of plastics was crucial for determining carbon emissions from incineration-based MSW management systems., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Huan Li reports financial support was provided by National Key R&D Program of China. Huan Li reports financial support was provided by Shenzhen Science and Technology Innovation Committee., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The widespread use of plastic mulch film (PMF) has led to significant environmental pollution, with PMF residues dispersed and mixed with straw and soil, posing challenges for recycling. Here, we proposed the mobile pyrolysis facility for the cotton straw and mulch film mixture (CMM) to mitigate the collection, storage, and transportation costs, while the application of co-pyrolysis technology for CMM conversion could improve the added value of products. Additionally, centralized combustion power generation and centralized pyrolysis systems were also established to evaluate and compare their sustainability from economic and environmental perspectives. Results showed that mobile pyrolysis has better economic performance than the centralized scenarios, due to its high internal rate of return (31 %) and significant net present value (29.21 M USD). Meanwhile, the mobile pyrolysis facility achieved a GWP of -1.298 kgCO 2 -eq/kg, reducing emissions by 70.79 % and 38.82 % compared to the two centralized scenarios. In conclusion, mobile pyrolysis technology provides a promising solution for PMF residue recycling because of its economically competitive approach with a lower carbon footprint., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Jiahua Zhu reports financial support was provided by National Natural Science Foundation of China. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper]., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The significant production of municipal solid waste incineration fly ash (MSWI FA) underscores the importance of developing efficient solidification materials. This study employed MgO and CaO for immobilizing MSWI FA (with a 70% fly ash incorporation), and the immobilization effect was compared with that of Portland cement (PC). Experimental findings revealed that MgO exhibited the most effective stabilization for heavy metals (Cd, Cu, Pb, and Zn) compared to CaO and PC. XRD, FTIR, TG, and SEM analysis indicated that the principal hydration products in MSWI FA binders solidified with MgO, CaO, and PC were Mg(OH) 2 , CaCO 3 , and C-S-H gel, respectively. Mg(OH) 2 efficiently immobilized heavy metals through chemical complexation and surface adsorption mechanisms. The MgO-treated MSWI FA demonstrated the highest residual fractions and the lowest easily leachable fractions. Moreover, the leaching characteristics of heavy metals were significantly influenced by the pH level, so MgO-treated MSWI FA with a leachate pH of 9.18 achieved the precipitation and stabilization of most heavy metals. In summary, this study provided an effective material selection for MSWI FA immobilization and presented a novel strategy for MSWI FA management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Non-governmental organizations (NGOs) play a critical role in addressing solid waste management (SWM) challenges in remote mountain communities, including the ecologically fragile Himalayan region. This study evaluates the impact of Healing Himalayas, an NGO, in Rakchham village, Himachal Pradesh, India. The objectives were to evaluate the effectiveness of Healing Himalayas' decentralized SWM model in promoting stakeholder engagement and resource recovery, assess the role of collaborations between local authorities and the NGO in financing waste management practices, investigate the influence of tourism and seasonal variations on solid waste generation patterns and waste management practices in Rakchham, and material recovery facilities, followed by glass (36.7%), paper/cardboard (18.4%) and metal (4.1%). A fee-based system involving the local village council funded waste operations. Waste generation exhibited significant seasonal fluctuations, with tourism influxes driving increased volumes. Healing Himalayas' initiatives promoted community participation, with over 15 awareness workshops conducted. Key challenges included limited financial resources, inadequate infrastructure, lack of advanced treatment facilities and need for context-specific solutions like efficient wet waste management in cold climates. The study highlights Healing Himalayas' decentralized model's success in fostering stakeholder engagement, behavioural change and resource recovery. The findings inform effective strategies for NGO-led waste management initiatives tailored to remote Himalayan communities., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Increasing municipal solid waste (MSW) production poses challenges for sustainable urban development. Modern energy-from-waste (EfW) facilities incinerate MSW, reducing mass and recovering energy. In the UK, MSW incineration bottom ash (MSW IBA) is primarily reused in civil engineering applications. This study characterizes UK-produced MSW IBA, examining its pH-dependent leaching behaviour and response to environmental lixiviants. Results show predominant components include a melt phase, primary glass and fine ash aggregations, and a chemical composition dominated by SiO 2 (30-50 %), CaO (∼15 %), Fe 2 O 3 (∼10 %), and Al 2 O 3 (∼8%). X-ray absorption near edge structure (XANES) analysis shows that Zn and Cu are most likely oxygen-bound (adsorbed to oxy-hydroxides and as oxides) with some sulphur bound. Polychlorinated biphenyls (PCBs) and polychlorinated dibenzodioxins/furans (PCDD/Fs) are well below regulatory limits, and polycyclic aromatic hydrocarbons (PAHs) were undetectable. Leaching tests indicate trace elements mobilize at pHs ≤ 6. With a natural pH of 11.3 and high buffering capacity, significant acid inputs to the MSW IBA are required to reach this pH, which are improbable in the environment. Wood chip additions increase leachate's dissolved organic carbon (DOC) and reduce pH, but had minimal impact on metal-leaching behaviour. Synthetic plant exudate solutions minimally affect metal leaching at realistic concentrations, only enhancing leaching at ≥ 1500 mg l -1 DOC. This work supports MSW IBA's low-risk in specified civil engineering applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The recent over production of municipal solid waste (MSW) poses a significant threat to both the ecosystem and human health. Utilizing MSW for agricultural purposes has emerged as a promising strategy to reduce solid waste disposal while simultaneously increasing soil fertility. To explore this potential solution further, an experiment was designed to assess the impact of varying concentrations of MSW (25%, 50%, and 75%) on the proximate composition of 15 different vegetable species. The experiment, conducted between 2018 and 2019, involved treating soil with different levels of solid waste and analyzing the proximate components, such as crude protein, dry matter, crude fiber, crude fat, and moisture content, in the 15 selected crops. The results indicate that the application of 25% MSW significantly increased the levels of crude protein, crude fiber, dry matter, and fat in Spinacia oleracea, Solanum tuberosum, Solanum melongena, and Abelmoschus esculentus. Conversely, the addition of 75% MSW notably elevated the moisture and ash content in Cucumis sativus. Correlation and scatter matrix analyses were conducted to elucidate the relationships between the protein, fiber, dry matter, ash, and fat contents. Principal component analysis and clustering confirmed the substantial impact of Treatment_1 (25% MSW) and Treatment_3 (75% MSW) on the proximate composition of the aforementioned vegetables, leading to their categorization into distinct groups. Our study highlights the efficacy of using 25% MSW to enhance the proximate composition and nutritional value of vegetables. Nonetheless, further research is warranted to investigate the mineral, antioxidant, vitamin, and heavy metal contents in the soil over an extended period of MSW application., (© 2024. The Author(s).)

A key question in anaerobic microbial ecology is how microbial communities develop over different stages of waste decomposition and whether these changes are specific to waste types. We destructively sampled over time 26 replicate bioreactors cultivated on fruit/vegetable waste (FVW) and meat waste (MW) based on pre-defined waste components and composition. To characterize community shifts, we examined 16S rRNA genes from both the leachate and solid fractions of the waste. Waste decomposition occurred faster in FVW than MW, as accumulation of ammonia in MW reactors led to inhibition of methanogenesis. We identified population succession during different stages of waste decomposition and linked specific populations to different waste types. Community analyses revealed underrepresentation of methanogens in the leachate fractions, emphasizing the importance of consistent and representative sampling when characterizing microbial communities in solid waste., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Francis de los Reyes reports financial support was provided by Environmental Research and Education Foundation. Morton Barlaz reports a relationship with Environmental Research and Education Foundation that includes: board membership. Co-author Morton Barlaz is Emeritus Editor of Waste Management. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.]., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

As part of its commitment to the United Nations Framework Convention on Climate Change, the U.S. annually develops a national estimate of methane emissions from municipal solid waste (MSW) landfills by aggregating activity data from each facility. Since 2010, the U.S. has reported a 20 % decrease in MSW landfill emissions despite a 21 % increase in tons disposed. Operator-submitted data were investigated to understand the causes of this decline. In the U.S., operators of landfills with a gas collection and control system (GCCS) calculate their facility's emissions via two separate approaches - (1) first-order decay (FOD) and (2) collection efficiency assumption (CEA) - and select either result to feed into the annual inventory. The FOD model predicts methane generation proportional to waste disposal and that approach calculated a 19 % increase in total methane generated from 2010 to 2022, whereas generation via the CEA approach decreased by 8.9 %. The amount of measured methane collected has increased 7.5 % for the same years. Discrepancies between the two models' generated methane, assumed gas collection efficiencies, and oxidized methane compound into substantive differences in national estimates. Operators more frequently select the CEA method, which results in decreased national estimates. If only the FOD method was used, U.S. MSW landfill emissions would be 1.3-1.7 times greater than current estimates which is similar to recent extrapolations from remote sensing campaigns in the U.S. Both models contain parameters with large inherent uncertainty. Without measurement methods that continuously quantify both point-source and diffuse emissions, an assessment of either equation's accuracy cannot be made., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Plastic mismanagement and its subsequent pollution by rapid economic development and urbanisation pose significant challenges for modern world society. Notwithstanding one of the main sources for macro plastic leakage into the ocean from land, precise assessment of plastic pollution origins from Southeast Asia is yet to be clearly examined. In order to make informed decisions and prioritise areas of improvement it is required to better understand the waste leakage dynamics at the local level. In this work, the Waste Flow Diagram (WFD) was applied to understand the sources and fates of plastics leaking from the solid waste management system for the case of Tuy Hoa City, Phu Yen, Vietnam. The study shows scenarios of leakage into the aquatic environment ranging from 0.8 to 2.7 kg/cap/year, which originates mainly from the collection system. Targeted improvements to this stage of the service could reduce leakages and the overall environmental impacts of mismanaged plastic waste. The results of this study show the necessity and importance of having up to date and reliable data to better inform stakeholders and service planning, facilitating efficient action against plastic pollution. As the first peer-reviewed scientific article critically applying the WFD, this work highlights the steps and challenges of the methodology and critically analyses different methodological pathways., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Passive methane oxidation biosystems (PMOBs) are developed as an innovative and cost-effective solution to reduce methane (CH 4 ) emissions from municipal solid waste landfills. A PMOB consists of a methane oxidation layer (MOL) and an underlying gas distribution layer (GDL). The length of unrestricted gas migration (LUGM) has been recently proposed as the design criterion for PMOBs where the LUGM is calculated as the horizontal length along the MOL-GDL interface with the volumetric gas content (θ a ) exceeding the threshold volumetric gas content (θ a,occ ). This paper examined water and gas migration within three PMOBs with different MOL-GDL interfaces subject to precipitation and evaporation using verified numerical models. The results show that the use of a single-phase flow model underestimates the LUGM values of the PMOB for heavy precipitation events, and a two-phase flow model should be used to calculate both the LUGM and the total gas mass flow rate into the MOL when designing PMOBs. Both zig-zag and trapezoidal MOL-GDL interfaces can redistribute the gas mass flow rate at the MOL-GDL interface, while the trapezoidal MOL-GDL interface slightly outperforms the zig-zag MOL-GDL interface for enhancing the total gas mass flow rate into the MOL when comparing with the planar MOL-GDL interface. The zig-zag and trapezoidal MOL-GDL interfaces allow gas migration in the upper part of each PMOB segment even when the lower part of each PMOB segment was filled with water, and thus have a potential to minimize hotspot formation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Climate impacts of landfill gas emissions were investigated for 20- and 100-year time horizons to identify the effects of atmospheric lifetimes of short- and long-lived drivers. Direct and indirect climate impacts were determined for methane and 79 trace species. The impacts were quantified using global warming potential, GWP (direct and indirect); atmospheric degradation (direct); tropospheric ozone forming potential (indirect); secondary aerosol forming potential (indirect) and stratospheric ozone depleting potential (indirect). Effects of cover characteristics, landfill operational conditions, and season on emissions were assessed. Analysis was conducted at five operating municipal solid waste landfills in California, which collectively contained 13% of the waste in place in the state. Climate impacts were determined to be primarily due to direct emissions (99.5 to 115%) with indirect emissions contributing -15 to 0.5%. Methane emissions were 35 to 99% of the total emissions and the remainder mainly greenhouse gases (hydro)chlorofluorocarbons (up to 42% of total emissions) and nitrous oxide. Cover types affected emissions, where the highest emissions were generally from intermediate covers with the largest relative landfill surface areas. Landfill-specific direct emissions varied between 683 and 103,411 and between 381 and 37,925 Mg CO 2 -eq./yr for 20- and 100-yr time horizons, respectively. Total emissions (direct + indirect) were 680 to 103,600 (20-yr) and were 374 to 38,108 (100-yr) Mg CO 2 -eq./yr. Analysis time horizon significantly affected emissions. The 20-yr direct and total emissions were consistently higher than the 100-yr emissions by up to 2.5 times. Detailed analysis of time-dependent climate effects can inform strategies to mitigate climate change impacts of landfill gas emissions., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Derek C. Manheim reports financial support was provided by California Air Resources Board. Derek C. Manheim reports financial support was provided by CalRecycle]., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Rapid expansion in urban areas has engendered a superfluity of municipal solid waste (MSW) stemming from contemporary civilization, encompassing commercial sectors and human undertakings. Kerbside waste, a type of MSW, has the potential for recycling and reuse at the end of its first life cycle, but is often limited to a linear cycle. This study aimed to assess the life cycle costs of different separation and recycling methods for handling kerbside waste. A new life cycle cost model, drawing from the circular economy's value retention process (VRP) model, has been created and applied to assess the continuous recycling of kerbside glass. The study investigates two key separation techniques, kerbside recycling mixed bin recycling (KRMB) kerbside glass recycling separate bin (KGRSB) and analyses their impact on the life cycle cost of the recycling process. Additionally, the research explores two approaches of recycling and downcycling: closed-loop recycling, which pertains to the recycling of glass containers, and open-looped recycling, which involves the use of recycled glass in asphalt. The results showed when use annually collected waste as the functional unit, the KRMB model incurred lower costs compared to the KGRSB model due to its lower production output. However, when evaluated over a 1-ton production of glass container and asphalt, the KGRSB method demonstrated superior cost performance with a 40-50% reduction compared to the KRMB method. The open-loop recycling method (asphalt) incurred a higher cost compared to the closed-loop recycling method due to its larger production volume over a 21-year period., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Selecting suitable Megacity Solid Waste Disposal (MSWD) sites is a challenging task in densely populated deltas of developing countries, exacerbated by limited public awareness about waste management. One of the major environmental concerns in Dhaka City, the world's densest megacity, is the presence of dumps close to surface water bodies resources. This study employed the Geographic Information System (GIS)-Analytic Hierarchy Process (AHP) framework to integrate geomorphological (slope and flow accumulation), geological (lithological and lineament), hydrogeological (depth to groundwater table and surface waterbody), socioeconomic (Land use land cover, distance to settlement, road, and airport), and climatological (wind direction) determinants, coupled by land-use and hydro-environmental analyses, to map optimal dumps (MSWD O) sites. The resulting preliminary (MSWD P ) map revealed 15 potential landfill areas, covering approximately 5237 hectares (ha). Combining statistical analysis of restricted areas (settlements, water bodies, land use) with AHP-based ratings, the MSWD O map revealed two optimal locations (2285 ha). Additionally, the hydro-environmental analysis confirmed the unsuitability of northern sites due to shallow groundwater (< 5.43 m) and thin clay, leaving 11 options excluded. Sites 12 (Zone A, 2255 ha) and 15 (Zone B, 30 ha), with deeper groundwater tables and thicker clay layers, emerged as optimal choices for minimizing environmental risks and ensuring effective long-term waste disposal. This study successfully integrates remote sensing, geospatial data, and GIS-AHP modeling to facilitate the development of sustainable landfill strategies in similar South Asian delta megacities. Such an approach provides valuable insights for policymakers to implement cost-effective and sustainable waste management plans, potentially minimizing the environmental risks to achieve Sustainable Development Goals (SDGs) 6, 11, 13, and 15., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Co-combustion of industrial and municipal solid wastes has emerged as the most promising disposal technology, yet its effect on unknown contaminants generation remains rarely revealed due to waste complexity. Hence, six batches of large-scale engineering experiments were designed in an incinerator of 650 t/d, which overcame the inauthenticity and deviation of laboratory tests. 953-1772 non-targeted compounds were screened in fly ash. Targeting the impact of co-combustion, a pseudo-component matrix model was innovatively integrated to quantitatively extract nine components from complex wastes grouped into biomass and plastic. Thus, the influence was evaluated across eight dimensions, covering molecular characteristics and toxicity. The effect of co-combustion with biomass pseudo-components was insignificant. However, co-combustion with high ratios of plastic pseudo-components induced higher potential risks, significantly promoting the formation of unsaturated hydrocarbons, highly unsaturated compounds (DBE≥15), and cyclic compounds by 19 %- 49 %, 17 %- 31 %, and 7 %- 27 %, respectively. Especially, blending with high ratios of PET plastic pseudo-components produced more species of contaminants. Unique 2 Level I toxicants, bromomethyl benzene and benzofuran-2-carbaldehyde, as well as 4 Level II toxicants, were locked, receiving no concern in previous combustion. The results highlighted risks during high proportion plastics co-combustion, which can help pollution reduction by tuning source wastes to enable healthy co-combustion., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Solid waste refers to the material that is discarded because of human activity. In developing countries like Ethiopia, rapid urbanization leads to the production of large amounts of solid waste in towns. As a consequence, it causes severe problems to human health, aesthetics, and the environment, particularly in Dangila Town. Therefore, this study aimed to assess household solid waste characteristics, quantity, and management practices. Data was collected for seven days in January 2020 from 73 households, which were divided into three income groups. Observations, interviews, field measurements, sorting, and open-ended questionnaires were used as data collection tools. The research showed that food waste and ash and dust were the most dominant fractions, comprising 41.04% and 26.18%, respectively. It was also revealed that 77.88%, 12.74%, and 9.38% of household solid waste was decomposable, recyclable, and disposable waste, respectively. Furthermore, the waste components showed a significant statistical difference among income groups, except for the metal and miscellaneous groups. The quantification result indicated that the per capita household generation rate was 0.26 kg/day. The management practice assessment found that most households did not practice integrated solid waste management options. They disposed of waste indiscriminately, leading to environmental pollution. The results of this study suggest that the municipality needs to create awareness among households regarding proper solid waste management practices. It is crucial to apply appropriate solid waste management mechanisms and establish a well-organized institution that will collect solid waste in the town and achieve a circular economy., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Food-waste biochar holds significant potential as a bio-solid fuel for achieving carbon neutrality; however, its high content of sodium (Na), potassium (K), calcium (Ca), chlorine (Cl), and nitrogen, inhibits its potential use. This study explored the effects of post-treatment with ascorbic, acetic, citric, and iminodiacetic acids on the properties of food-waste biochar and volatile ionic substances to establish a foundation for assessing both the environmental impact and practical use of food waste. Post-treatment with organic acids achieved 92% Cl-removal efficiency and induced deformation of the functional groups of food-waste biochar surfaces, leading to the re-adsorption of alkali and alkaline earth metals. This re-adsorption of alkali metal ions showed a distinct correlation with NO x mitigation. The amount of re-adsorbed Na and K varied based on the types of organic acids, resulting in different NO x emission reduction effects. Iminodiacetic acid was particularly effective in alleviating Ca and PO 4 volatilization, whereas citric acid exhibited the highest Ca elution performance, and the Ca-contained leachate is a potential source of CO 2 storage through indirect mineral carbonation. Acetic acid is the most feasible alternative, considering both economic and environmental aspects. The findings suggest that the post-treatment of food-waste biochar effectively mitigates air pollutants during combustion and is beneficial for sustainable biosolid fuel production and bio-waste management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Incineration is an effective method for reducing and safely treating municipal solid waste. However, microplastics (MPs) inevitably remain in the bottom ash, potentially introducing new pollution risks during subsequent treatment processes. This study conducted an analysis of the accumulation and release potential of MPs in bottom ash samples collected from 4 municipal solid waste incineration plants in Zhejiang, China. The results showed that the abundance of MPs ranged from 20 to 118 items g -1 . Remarkably, MPs were found to accumulate predominantly in smaller bottom ash particles below 4.75 mm accounted for up to 70% of the total MPs. Most MPs in the bottom ash were under 100 μm in size, with a majority exceeding 50% being less than 50 μm, typically manifesting as shafts and fibers. In scenarios of secondary crushing, the abundance of MPs increased gradually with the degree of bottom ash crushing. When bottom ash was crushed to a particle size of less than 0.6 mm, the abundance of MPs reached up to 87-901 items g -1 , which is 5-10 times higher than the original bottom ash. It is estimated that the annual release of MPs may reach up to 4.05 × 10 16 particles. Re-incinerating thoroughly crushed bottom ash at 600 °C successfully decomposed the MPs. Mechanical stress can significantly increase the risk of MPs releasing in bottom ash. This risk can be eliminated by using secondary incineration to achieve complete MPs decomposition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

With the increasing demand for Li, the recovery of Li from solid waste, such as Li-containing Al electrolytes, is receiving growing attention. However, Li-containing Al electrolytes often contain large amounts of F, leading to environmental pollution. Herein, a new method for preparing water-soluble Li salt from waste Li-containing Al electrolytes with high F and Na contents is proposed based on CaO roasting and water leaching. The effects of different roasting and leaching conditions on the Li leaching efficiency and reaction pathway were systematically investigated. Under the optimum processing conditions, the Li leaching efficiency reached 98%, while those of Na and F were 98.41% and 0.24%, respectively. Phase evolution analysis showed that the addition of CaO promoted the conversion of LiF and Na 2 LiAlF 6 to Li 2 O, whereas F entered the slag phase as CaF 2 , which could be reused as a raw material for steel refinement. Overall, this study proposes an efficient and environmentally friendly method for the treatment and resource utilization of waste Al electrolytes with high F and Na contents., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

A combined process of coagulation pretreatment and three-stage membrane aeration biofilm reactor (MABR) system was successfully applied for the first time to treat actual municipal solid waste leachate (MSWL), which was characterized by high concentrations of toxic hard-to-degrade organics and salinity. The results showed that 9.8%-21.3% of organics could be removed from actual MSWL by coagulation with polymeric aluminum chloride (PAC). Three-stage MABR contributed 95.6% of the chemical oxygen demand (COD) removal, with the influent COD concentration ranging from 6000 to 7000 mg/L. At the same time, the removal efficiencies of total nitrogen (TN) and ammonia (NH 4 + -N) could reach to 84.3% and 79.9% without the addition of external carbon source, respectively. The nitrifying/denitrifying bacteria were enriched in the biofilm including Thiobacillus, Azoarcus and Methyloversatilis, which supported the MABR with high nitrogen removal efficiency and significantly toxic tolerance. Principal component analysis (PCA) and the Pearson correlation coefficients (r) illustrated that aeration pressure is a crucial operational parameter, exhibiting a strong correlation between the MABR performance and microbial communities. This work demonstrates that MABR is an effective and low-energy option for simultaneous removal of carbon and nitrogen in the treatment of MSWL., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Biodegradable plastics, either fossil- or biobased, are often promoted due to their biodegradability and acclaimed environmental friendliness. However, as demonstrated by previous literature, considerable confusion exists about the appropriate source separation and waste management of these plastics. Present study investigated this confusion based on manual sorting analyses of waste sampled from packaging waste ( P ), biowaste ( B ) and residual waste ( R ) in an urban area of Austria. The results were evaluated relative to near-infrared sensor-based sorting trials conducted in a German urban area. Although existing literature has focused on waste composition analyses (mostly in stand-alone studies) of the three waste streams, the present study focused on identifying the specific types of biodegradable plastic items found in each of these streams. Supermarket carrier bags ( P  = 90, B  = 14, R  = 33) and dustbin bags ( P  = 2, B  = 46, R  = 6) were found in all three waste streams in the Austrian urban area. Similarly, in the German urban area dustbin bags ( P  = 1, B  = 106, R  = 3) were the common items. The results indicate that certain bioplastic items were present in more than one bin; thus, hinting that consumers are not necessarily aware of how-to source-separate the biodegradable plastics. This suggests that neither consumers nor current waste management systems are fully 'adapted' to bioplastics, and the management of these plastics' waste is currently not optimal., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

In the context of Circular Economy, the significance of municipal solid waste management systems (MSWMSs) has increased, as well as the need for comprehensive assessment tools of their sustainability. In the Life Cycle Thinking (LCT) framework, the Life Cycle Sustainability Assessment (LCSA), which is a methodology aiming to evaluate the environmental, economic, and social burdens throughout the various phases of waste management, has raised great interest. The paper describes the state-of-the-art of the implementation of LCT tools, with high regard to LCSA, for the evaluation of MSWMSs through their life cycle, with a deep focus on the use of both midpoint and endpoint categories. Drawing insights from an analysis of 69 case studies, the paper identifies the most frequently applied midpoint and endpoint categories for the sustainability assessment of MSWMSs. These categories are exposed in terms of their significance and applicability to specific waste management scenarios, providing valuable guidance for experts and researchers seeking to employ LCSA in MSWMSs assessments. Additionally, the paper outlines the limits associated with the implementation of LCSA, thereby highlighting areas for further research and improvement. In contrast to other reviews in this field, this paper uniquely focuses on the implementation of LCSA in the specific context provided by MSWMSs. By disseminating such insights, the paper aspires to foster the widespread adoption of LCSA by experts and researchers, ultimately advancing the sustainability discourse in municipal solid waste management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Rapid global urbanization and economic growth have significantly increased solid waste volumes, with hazardous waste posing substantial health and environmental risks. Co-processing strategies for industrial solid and hazardous waste as alternative fuels highlight the importance of integrated waste management for energy and material recovery. This study identifies and characterizes solid and hazardous industrial wastes with high calorific values from various industrial processes at Nirma Industries Limited. Nine types of combustible industrial wastes were analyzed: discarded containers (W1), plastic waste (W2), spent ion exchange resins from RO plants (W3), sludge from effluent treatment in soap plants (W4), glycerine foot from soap plants (W5), rock wool puff material (W6), fiber-reinforced plastic waste (W7), spent activated carbon (W8), and spent cartridges from reverse osmosis plants (W9). Physical characterization, proximate and ultimate analysis, heavy metal concentration evaluation, and thermogravimetric analysis were conducted to assess their properties, revealing high calorific values exceeding 2500 kcal/kg. Notably, W1 and W2 exhibited the highest calorific values (∼10,870 kcal/kg), followed by W6 and W8 (∼6000 kcal/kg) and W9 (∼8727 kcal/kg). Safe heavy metal levels are safe, and high calorific values support the prospects of energy recovery and economic and environmental benefits, reducing landfill reliance and enhancing sustainable waste management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Technological advances have led to the generation of novel streams of solid wastes, comprising materials previously excluded from traditional waste considerations. The absence of proper handling and management policies for these Emerging Solid Waste Streams (ESWSs) poses a great cause of concern. Proper estimation of current and future quantities is necessary for efficient policy making. This study, through a systematic literature review, analyses forecasting models for four major ESWSs: PV waste, e-waste, battery waste, and biomedical waste. A total of 40 modelling methodologies which successfully forecast the quantities of these ESWSs are identified and analyzed in this review. These highly heterogeneous models are classified into several crucial categories based on the modelling method, independent variable, geographical scale and data type involved. This categorization proves to be pivotal in the selection of an appropriate forecasting model. Around 40 modelling methods and 100+ independent variables, crucial for a successful forecast are identified and categorized. This study also focuses on the uncertainty involved in input data, a factor contributing to inaccurate predictions. It further entails identifying and analysing potential data sources, examining the rationale behind their selection, and providing recommendations for choosing suitable data sources. Beyond analysis, potential future areas of research and gaps involved in the field of forecasting ESWSs have also been highlighted. Serving as a valuable guide for beginners, the research also proposes a methodology to navigate the intricacies of forecasting ESWSs, contributing to both our understanding of forecasting models and the development of robust waste management policies in the evolving technological landscape., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Sensor-based material flow monitoring allows for continuously high output qualities, through quality management and process control. The implementation in the waste management sector, however, is inhibited by the heterogeneity of waste and throughput fluctuations. In this study, challenges and possibilities of using different types of sensors in a lightweight packaging waste sorting plant are investigated. Three external sensors have been mounted on different positions in an Austrian sorting plant: one Light Detection and Ranging (LiDAR) sensor for monitoring the volume flow and two near-infrared (NIR) sensors for measuring the pixel-based material composition and occupation density. Additionally, the data of an existing sensor-based sorter (SBS) were evaluated. To predict the newly introduced parameter material-specific occupation density (MSOD) of multi-coloured polyethylene terephthalate (PET) preconcentrate, different machine learning models were evaluated. The results indicate that using SBS data for both monitoring of throughput fluctuations caused by different bag opener settings as well as monitoring the material composition is feasible, if the pre-set teach-in is suitable. The ridge regression model based on SBS was comparable (RMSE = 3.59 px%, R ² = 0.57) to the one based on NIR and LiDAR (RMSE = 3.1 px%, R ² = 0.68). The demonstrated feasibility of the implementation at plant scale highlights the opportunities of sensor-based material flow monitoring for the waste management sector and paves the way towards a more circular plastics economy., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Municipal solid waste (MSW) characterization plays a pivotal role in devising effective waste management strategies conducive to fostering a circular economy. This study presents composition analysis across twenty-four subcategories sourced from residential, commercial, and industrial sectors in Kuwait. The study is conducted in accordance with the Standard Test Method for Determination of the Composition of Unprocessed Municipal Solid Waste (ASTM D5231). The results indicate that organic waste comprises 45.3%, followed by paper waste (19.9%) and plastics (19.8%). The remaining waste comprises glass waste (3.5%), diapers (2.7%), textiles (2.6%) and other waste. Paper waste (19.9%) consists mainly of mixed paper (12.1%), cardboard (3.7%), newspaper (3.3%), printer printouts (0.6%) and other office paper (0.2%). Plastic waste (19.8%) consists mainly of film (11.2%), PET (3.1%), HDPE (1.1%) and other mixed plastics (4.4%). Residential and mixed areas have the highest proportion of organic waste. Commercial areas produce the highest proportion of wastepaper (22.4%) and textiles (3.7%). Industrial areas produce the highest proportion of plastic waste (29.1%), most of which is film (17.3%). The study also provides an overview of the MSW management system in the country, an overview over the legislative framework, and forecasts of future waste generation rates with comparison to historical baselines. Implications : The precise and up-to-date characterization of municipal solid waste is imperative for scholarly journal submissions, as it establishes a foundational understanding of waste composition, aiding researchers and policymakers in the development of effective waste management strategies, resource recovery initiatives, and sustainable solutions to address the evolving challenges in waste management systems.This study provides detailed composition analysis for twenty-four municipal solid waste (MSW) subcategories collected across different sources: residential, commercial, industrial, and mixed areas. Time series forecasting is applied to predict MSW generation based on historical data obtained through the local municipality over the past decade. Factorial analysis is applied to investigate changes across source areas, and a hypothesis test is used to compare the current MSW composition against previous baselines. The results demonstrated significant variation across most waste categories. The plastic waste proportion has increased by 48.5% compared to 2013 data, despite awareness campaigns. Paper waste has also increased in proportion from 6.8% to 16.2%; this increase is associated with the mixed paper subcategory, which is mostly used for packaging. The composition data provided in this study are necessary for long-term monitoring, strategy assessment, and legislation associated with waste reduction and remediation.

The Fossetto landfill has operated in the municipality of Monsummano Terme (Tuscany, Italy) since 1988, being considered a state-of-the-art landfill for 35 years. Initially, Fossetto acted as a conventional sanitary landfill for mixed municipal solid waste. With changes in regulations and technology, the Fossetto landfill was gradually equipped with a biogas recovery and valorisation system, a mechanical-biological treatment (MBT) plant in 2003 and a reverse osmosis leachate treatment plant, so the concentrated leachate has been recirculated back into the landfill body since 2006. Long-term biogas monitoring, enables the calculation of the efficiency of biogas recovery using a rather simplified methodology, which was assessed as being approximately 40% over the prior ten-years period. This value was lower than expected, confirming the results of previous studies and indicating the need of attributes. Applying the USEPA LandGEM model showed that the adoption of MBT substantially reduced biogas generation yields and rates by up to approximately 90% which was facilitated by the adoption of landfill leachate recirculation transforming the conventional landfill into a bioreactor. Detailed fugitive emission monitoring has allowed the evaluation of the impact of the cover type (final or temporary) and the emissions hotspots. From these results, possible remedial actions have been suggested including the more frequent monitoring of the fugitive emissions using simple and cost-effective methods (e.g., UAVs). Approximately 50% of fugitive emissions can be attributed to emissions hotspots, which reduce biogas recovery and the efficiency of temporary covers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)