Municipal Solid Waste Research Articles

Toward sustainable waste-to-energy solutions: risk allocation and technological innovations in public-private partnerships

ABSTRACT The energy challenge and environmental degradation are currently two of the biggest obstacles to sustainable global growth. Due to emerging countries’ rapid industrialization and population increase, people have been migrating from rural to urban areas. One of the primary causes of environmental deterioration in Egypt is the country’s hundreds of tons of municipal solid waste generated every day, as well as the country’s struggles with waste management and energy production. Waste-to-energy (WTE) programs show promise as a remedy. However, given the inherent complexity and unpredictability of these endeavors, a careful examination of risk allocation methods is important, especially in the context of public-private partnerships. The present paper intends to identify important risk considerations, evaluate their allocation methodologies, and distribute insights for stakeholders and policymakers involved in WTE projects in Egypt through an extensive assessment of the literature and case studies subsequently in practice. In order to reduce the risks associated with Waste-to-Energy (WTE) projects in Egypt, the current paper considers eight categories: land accessibility, availability, and site risks; social risks; environmental and human health concerns; design risks; construction risks; operation risks; financial market risks; and collaboration risks.

Drivers of change behind the spatial distribution and fate of typical trace organic pollutants in fresh waste leachate across China

There have been growing concerns regarding the health and environmental impacts of trace organic pollutants (TOPs). However, fresh leachate from municipal solid waste (MSW) has been overlooked as a potential reservoir of TOPs. Therefore, we investigated 90 legacy and emerging TOPs in fresh leachate from 14 provinces and municipalities in China. Additionally, the fate and final discharge impacts of TOPs in 14 leachate treatment systems were analyzed. The results revealed that the detection rate of 90 TOPs was over 50 % in all samples. Notably, polychlorinated biphenyls, banned for 40 years, were frequently detected in fresh leachate. The concentration of pseudo-persistent TOPs (105–107 ng/L) is significantly higher than that of persistent TOPs (102–104 ng/L). Spatial distribution patterns of TOPs in fresh leachate suggest that economy, population, climate, and policies impact TOPs discharge from MSW. For example, economically developed and densely populated areas displayed higher TOPs concentrations, whereas warmer climates facilitate TOPs leaching from MSW. We confirmed that waste classification policies were a key driver of the decline in multiple TOPs in leachate. Mass balance analysis shows that the final effluent and sludge from current dominant leachate treatment systems contain refractory TOPs, especially perfluoroalkyl acids, which must be prioritized for control. This paper was the first comprehensive investigation of multiple TOPs in fresh leachate at a large geographic scale. The factors affecting the occurrence, spatial distribution, and fate of TOPs in fresh leachate were revealed. It provides a valuable reference for the establishment of policies for the management of TOPs in MSW and the associated leachate.

Kajian Tekno Ekonomi Terkait Konversi Limbah Biomassa Refuse Derived Fuel (RDF) Menjadi Listrik Melalui Metode Gasifikasi Tiga Tingkat dan Mesin Diesel Dual Fuel di Pulau Batam

The increasing energy demand has led to a decrease in the availability of fossil fuels, making it necessary to seek renewable alternative energy sources. One of the alternative energy solutions that is currently being widely developed is biomass. Biomass can be converted into renewable energy through a process called gasification. Gasification is the conversion process of solid fuels, often referred to as Municipal Solid Waste (MSW), which can be processed into Biomass Refuse Derived Fuel (RDF) for the three-stage gasification process to produce syngas. Syngas can then be used as fuel for diesel engines to generate electricity in a “Waste to Electric” system. This study utilizes a diesel engine with a dual-fuel system. The objective of operating the diesel engine with a dual-fuel system is to determine the impact of using syngas, obtained from the gasification of RDF pellets, in a diesel engine with a dual-fuel system. The dual-fuel diesel system operates using two types of fuel: diesel fuel and gas fuel. The gas fuel used is syngas resulting from the gasification of RDF biomass pellets. During the gasification process, variations in the air ratio will be adjusted in the pyrolysis, oxidation, and reduction zones with air ratio comparisons of 0:10:0, 1:8:1, 2:7:1, and 1:7:2. The syngas produced from the gasification process will be used as fuel for the dual-fuel diesel engine. The performance characterization of the dual-fuel diesel engine will be conducted by testing the engine at 5000 rpm with load variations from 500 watts to 5000 watts in 500-watt increments, and by varying the mass flow rate of the syngas by adjusting the syngas valve opening. This study aims to demonstrate that RDF has promising potential as a renewable electricity source. The three-stage gasification process has proven effective in converting RDF into high-quality syngas. The dual-fuel diesel engine can operate stably and produce electricity with lower emissions compared to conventional diesel engines. The utilization of RDF biomass waste for power generation through three-stage gasification and dual-fuel diesel engines offers a sustainable solution to waste management issues and provides environmentally friendly electricity on Batam Island.

Organic Fraction Municipal Solid Waste Compost and Horse Bean Green Manure Improve Sustainability of a Top-Quality Tobacco Cropping System: The Beneficial Effects on Soil and Plants

Organic Fraction Municipal Solid Waste Compost and Horse Bean Green Manure Improve Sustainability of a Top-Quality Tobacco Cropping System: The Beneficial Effects on Soil and Plants

Influence of mandatory waste classification on environmental and economic impacts of residual waste treatment in Xiamen, China.

Mandatory waste classification has been widely considered as an effective solution for reducing the production and treatment amount of municipal solid waste. However, there is limited evidence regarding whether and how waste classification can affect the composition of residual waste (RW) and its environmental economic impacts. Here, an accounting method recommended by the Intergovernmental Panel on Climate Change, field surveys and cost-benefit analysis was utilized to investigate the changes in RW composition, environmental impacts and economic benefits under the waste classification policies implementation in Xiamen, China. This study found that: (1) The implementation of waste classification policies led to a significant increase in recyclable content from 17% to 51% and a decrease in organic content from 56% to 32%. (2) Waste classification effectively reduces greenhouse gas emissions from landfilling and incineration by an additional 0.34 tCO2-eq t-1 RW. (3) The introduction of mechanical recycling achieves a saving of 0.47 tCO2-eq t-1 RW at 40% recycling efficiency, a 4.5-fold increase compared to business as usual (BAU). (4) The operational benefits (900 yuan t-1 RW) from the recyclables sorting system offset the total expenses of investment, operation and waste disposal. The study successfully demonstrated that RW source-classified management can optimize the structure of waste composition, reduce environmental emissions and offer detailed guidance for the development of solid waste management systems in other cities in China.

Results of the cyclic triaxial testing on mechanically-biologically treated waste.

Accurate assessment of the dynamic strength characteristics of mechanically-biologically treated (MBT) waste is crucial for the construction and safe operation of landfill sites. Herein, samples of MBT waste from the Hangzhou Tianziling landfill were collected and subjected to consolidated undrained cyclic triaxial tests under four confinement levels and six cyclic stress ratios (CSRs). Under cyclic loading, the MBT waste exhibited a critical CSR. If the CSR exceeds the critical value, the MBT waste specimen rapidly undergoes deformation and failure. Dynamic strength of MBT waste decreases with an increase in the number of cyclic vibrations and increases with an increase in confining pressure. Considering the influence of cyclic vibrations and confining pressure, a formula for dynamic strength in terms of cyclic vibrations and confining pressure has been established. The dynamic shear strength parameter ranges for MBT waste were obtained under different seismic magnitudes. We compared the dynamic and static shear strength parameters of MBT waste and municipal solid waste. These study findings can serve as a reference for the dynamic stability analysis of MBT waste landfills.

Municipal Solid Waste Management and Health Risks: Application of Solid Waste Safety Plan in Novi Sad, Serbia

Inadequate solid waste management (SWM) can cause environmental contamination and health risks. Minimizing the health risks from SWM practices requires the identification of linkages between potential sources of exposure, environmental transport pathways, and adverse health outcomes. A safety planning approach can represent an innovative tool for reducing such risks. In previous research, we introduced the solid waste safety plan (SWSP) concept, only focusing on the health risk ranking assessment matrix. Here, we demonstrate the application of the SWSP framework in a case study of the municipal landfill of Novi Sad, Serbia. We identify potential hazards and assessed the likelihood and severity for them, using a combination of quantitative and semi-quantitative approaches to estimate risk levels for each identified hazard. Hazards deemed high and very high risks for the community and workers include groundwater contamination from leachate, airborne contaminants from combustion and non-combustion processes, and worker injuries associated with waste combustion. Control measures for each are identified, together with a corresponding cost analysis. Adding a final top cover to the landfill and introducing a collection, transport, and treatment system for the biogas would address hazards presenting high health risks but are also among the highest costs. While we demonstrate the approach and utility of an SWSP in a research context, future work is needed to assess the use of the SWSP by local communities or SWM utilities.

Application prospect of MSWI FA in the field of construction engineering

This study aims to investigate the feasibility of partially substituting municipal solid waste incineration fly ash (MSWI FA) in the field of construction engineering for ordinary Portland cement, in response to the resource scarcity and environmental issues associated with conventional silicate cement. It is found that MSWI FA has high potential in replacing cement, through the analysis of macro-properties, electron microscopy, Structural, and leaching characteristics of heavy metals. The compressive strengths of 3 days and 28 days are 7.15 MPa and 21.83 MPa, respectively, meeting the requirements for various construction applications including backfilling in mining voids, highway subgrades, backfilling behind shield tunnel walls, and grouting reinforcement in soft soil layers. Furthermore, the common leaching concentrations of heavy metals are significantly lower than the landfill standards, suggesting that environmental concerns may no longer be a deterrent to the utilization of MSWI FA. In terms of its comprehensive performance, it can have broad development space in the field of construction in the future.

Black soldier fly larvae efficiently bioconvert the organic fraction of municipal solid waste thanks to the functional plasticity of their midgut

Abstract The saprophagous larvae of Hermetia illucens show promising potential as effective agents for bioconverting organic waste and by-products into valuable biomass. Their capability to efficiently transform organic substrates, varying in nutrient content, origin, texture, and moisture, is strictly correlated with the morphofunctional complexity of their digestive system and the associated microbiota. In addition, post-ingestion mechanisms are set in motion to regulate the midgut activity depending on the feeding substrate, thus ensuring the nutritional requirements of the larvae. This study aims to assess the capability of H. illucens larvae to grow and biotransform the organic fraction of municipal solid waste (OFMSW). In particular, the larvae were reared on substrates mimicking the OFMSW with different nutrient content, and their growth and bioconversion performance, as well as the quality of larval and pupal biomass were evaluated. Our results demonstrate that the nutritional composition of the rearing substrates had minimal impact on the efficiency of the bioconversion process and on the protein, lipid, and chitin content of the insect biomass. This was due to a fine transcriptional regulation of genes encoding enzymes involved in protein, polysaccharide, and lipid digestion in midgut cells. As a consequence, larvae reared on OFMSW with the lowest protein, starch, and lipid content exhibited a significant increase in protease, amylase, and lipase activities. Overall, this study highlights the value of H. illucens larvae in valorising the OFMSW, demonstrating that variations in its composition do not significantly affect the quality of the bioconversion process. These findings hold significant practical implications as current strategies for OFMSW treatment remain unsatisfactory and innovative approaches are needed to enhance bio-waste recycling and reduce the environmental impact of waste management.

Occupational health problems among waste collectors in a metropolitan city: a cross-sectional study

Waste collectors are often exposed to various occupational problems. This study aims to assess occupational health problems of waste collectors and personal protective equipment use in Kathmandu Metropolitan City. A cross-sectional study was conducted in 2022 among 158 household waste collectors. Data was collected using a self-constructed questionnaire through face-to-face interviews from April to September 2022. Twelve wards were randomly chosen among all thirty-two wards, and all workers from the selected wards were included in the study. Data entry was done in Epi-data, and analysis was in the SPSS version 25. The chi-square test measured the association between demographic and occupational diseases. Occupational diseases such as musculoskeletal disorders (65.2%), physical injuries (61%), gastrointestinal tract infections (18.4%), and skin allergies (32.9%) were reported. Almost all workers used masks and gloves. Sociodemographic factors such as age and musculoskeletal disorder (MSD) showed significant association (p-value=0.001). Additionally, variables like sex showed a significant association with occupational health problems, such as disease faced by waste collectors (P-value of 0.049). Similarly, other variables like educational status and using separate clothing at work (p-value 0.004), changing clothes daily (p-value, <0.01), work experience and bathing daily after work (p=0.01), and changing clothes (p=0.003) also showed a significant association. Our study showed that almost all workers experienced occupational diseases. These findings highlighted the need to emphasize occupational health within municipal solid waste management to develop a safer and healthier work environment for waste collectors.

Composting as a Sustainable Solution for Organic Solid Waste Management: Current Practices and Potential Improvements

With increases in global population and urbanization, the production of Municipal Solid Waste (MSW) is growing rapidly, thus contributing to social and environmental concerns for sustainable waste management. This study addresses the research gap in optimizing composting, hypothesizing that integrating best practices and recent innovations can enhance the efficiency of the process. Data were collected through a systematic review of existing literature using Google Scholar and Scopus databases. The review provides an overview of municipal organic waste composting, outlining its processes, benefits, and challenges with the aim of identifying key area of further improvement and possibilities of adopting recent technological innovations. The analysis emphasized that technological advances in composting, as microbial inoculants or in-vessel composting have greatly improved the efficiency and quality of the resulting compost. However, several challenges remain, including managing contaminants such as heavy metals and microplastics, ensuring the compost quality and safety and addressing socioeconomic barriers that prevent widespread adoption. Moreover, process optimization, environmental and economic evaluation, as well as political and public involvement are essential to unlock the whole potential of composting systems.

Preparation of porous plate from municipal solid waste incineration fly ash and its application in a biofilm batch reactor

AbstractThe reutilization of municipal solid waste incineration (MSWI) fly ash is a prominent area of research. This study focused on creating fly ash porous plate filler (FAPPF) by using techniques, such as water extraction, milling, component adjustment, and sintering. The produced FAPPF was then used to cultivate a biofilm for wastewater treatment. The key parameters included a two‐stage water extraction process with a 5:1 liquid‐to‐solid ratio; milling for 1, 2, and 4 h; component adjustment using waste glass powder, milled fly ash, palygorskite powder, and peanut shell powder at a 7:1:1:1 mass ratio; and sintering temperatures ranging from 700 to 1000°C. For the biofilm cultivation and treatment, this study employed semisimulated sewage in a sequencing biofilm batch reactor system. The results revealed the FAPPF had no heavy metal leaching, with a porosity of 48.53%–54.68%. Approximately 90% of its composition was derived from waste materials. Furthermore, scanning electron microscopy microanalysis revealed an internally stable liquid‐phase sintering structure. Finally, a mature biofilm developed in 21 days, achieving maximum removal rates of 95.48% for chemical oxygen demand and 78.4% for ammonia nitrogen. This article confirms the sustainable recycling potential of MSWI fly ash.

Photosynthetic Activities, Phytohormones, and Secondary Metabolites Induction in Plants by Prevailing Compost Residue.

Compost residue enriches soil health with the potential to enhance plant metabolism and hormonal balance, but has not yet been studied. A study was performed to determine how prevailing compost residue induces tomato (Solanum lycopersicum 'Scotia') plant morpho-physiology, phytohormones, and secondary metabolites. Plants were grown in soils with a previous history of annual (AN) and biennial (BI) compost amendments. The controls were soil without compost (C) amendment and municipal solid waste compost (MSWC) alone. The MSWC- and AN-plants had similar and significantly (p < 0.05) highest growth and photosynthetic activities compared to the BI- or C-plants. Total phenolics and lipid peroxidase activity were significantly (p < 0.001) high in BI-plants, while hydrogen peroxide and antioxidant capacity were significantly (p < 0.001) high in AN-plants. MSWC-plants recorded the highest cis-abscisic acid, followed by AN-, and then BI- and C-plants. Cis-zeatin, trans-zeatin, and isopentenyladenine ribosides were detected in the MSWC- and AN-plants but not in the BI- or C-plants. Furthermore, gibberellins GA53, GA19, and GA8 were high in the MSWC-plants, but only GA8 was detected in the AN plants and none in the others. Besides, MSWC plants exhibited the highest content of 1-aminocyclopropane-1-carboxylic acid. Conjugated salicylic acid was highest in the BI-plants, while jasmonic acid-isoleucine was highest in MSWC-plants and C plants. In conclusion, prevailing compost chemical residues upregulate plant growth, phytohormones, and metabolic compounds that can potentially increase plant growth and abiotic stress defense. Future work should investigate the flow of these compounds in plants under abiotic stress.

Odor control technologies for municipal solid waste mechanical biological treatment plant: a review

Odor control technologies for municipal solid waste mechanical biological treatment plant: a review

A Hybrid Energy System Based on Externally Fired Micro Gas Turbines, Waste Heat Recovery and Gasification Systems: An Energetic and Exergetic Performance Analysis

The opportunities related to the adoption of synthetic gaseous fuels derived from solid biomass are limited by the issues caused by the peculiarities of the syngas. The aim of this paper is to analyze several possible layouts of hybrid energy systems, in which the main thermal source is the organic fraction of municipal solid wastes. The case of a small community of about 1000 persons is analyzed in this paper. The examined layouts coupled an externally fired micro gas turbine with a waste heat recovery system based on both an Organic Rankine Cycle and supercritical CO2 gas turbines. A thermodynamic analysis has been carried out through the use of the commercial software Thermoflex 31, considering the losses of each component and the non-ideal behavior of the fluids. The results of the numerical analysis highlight that the introduction of a waste heat recovery system leads to an increase of at least 16% in the available net power, while a cascade hybrid energy grid can lead to a power enhancement of about 29%, with a considerable increase also in the energetic and exergetic global efficiencies.

The Material and Energy Conversion Potential from Municipal Waste in Padang City: Business Chance and Future Prospective

Padang City, the capital city of West Sumatra Province, is expected to grow and reach a population of 1 million by 2035. However, this growth also means an increase in municipal solid waste, projected to be about 256,000 tons annually. At the same time, there is potential for waste-to-energy conversion in Padang City due to the demand for renewable energy and business opportunities. This study is based on existing literature and data, which were analyzed using a statistical approach and municipal solid waste management calculations. The study conducted scenarios that show potential energy conversions. The first scenario involves converting solid waste to gas and using it directly as biogas. The second scenario involves converting biogas from solid waste to electricity and distributing it for household use. The last scenario consists of using small and medium-sized biodigesters to convert gas into electricity, which will then be used as a charging station for electric vehicles (EVs). The first scenario can generate the most significant profit, while the third scenario suits small and medium businesses. However, each scenario has its pros and cons. Still, it's crucial to consider regulation issues, government support, and public awareness of the environmental problems to implement these waste-to-energy conversion practices on-site successfully.

Evaluating the Performance of Modified Geo-Synthetic Clay Liners

Waste products from human activity must always be controlled. Reusing some garbage is possible. But a lot of rubbish that could be more useful needs to be disposed of to protect the environment. Landfilling is one popular form of disposal. The most frequent issues with landfills are groundwater contamination and environmental deterioration, brought on by rainfall and leachate generated during the breakdown of organic materials. A landfill's liner is crucial to stop leachate migration and groundwater contamination. Since their development in 1986, Geo-Synthetic Clay Liners (GCLs) have gained popularity as a barrier solution for municipal solid waste landfills. In this study, fly ash and Kaolinite, two waste materials, are combined with bentonite in different percentages 10–30% and 50%, respectively to evaluate their potential usage as liner materials. Bentonite, in combination, is anticipated to function as a low permeability, self-healing, hydraulic barrier due to these swelling qualities.

A Recurrent Stochastic Configuration Network for Dynamic System Modeling and Its Application

In order to model nonlinear dynamic systems quickly and accurately, a recurrent stochastic configuration network (RSCN) with universal approximation ability is proposed in this paper. The method consists of network parameter learning and network structure determination. The network parameter learning strategy consists of input weights and the biases of hidden nodes generated randomly through a supervision mechanism, while the output weights of hidden nodes are determined by solving the least-squares problem. The network structure is determined incrementally by the training error of a single-layer recurrent neural network. The effectiveness of RSCN is tested and evaluated by using three nonlinear dynamic functions and historical data from a municipal solid waste incineration (MSWI) process. The experimental results show that the proposed method can improve modeling accuracy and reduce training time, which is valuable for applications in the field of industrial process modeling.

Enhancing sustainability of urban waste management through data envelopment analysis for municipal solid waste composting in Tehran, Iran

The critical necessity of decreasing energy consumption and environmental effects is vital in various facets of urban life, particularly in urban waste management. This research aimed to evaluate the energy flow, CExD, and Life Cycle of a composting system for Municipal Solid Waste (MSW) in Tehran province, Iran. The initial phase entailed assessing the energy flow and effectiveness of the composting system, while the subsequent phase focused on enhancing energy efficiency through the application of Data Envelopment Analysis (DEA) to determine an optimal energy consumption strategy for conserving energy and reducing environmental impacts in Tehran's MSW composting system. Over a 90-day period, the analysis of energy usage revealed an energy input and output of 417.30 GJ (8500 t MSW)−1, with 227.02 GJ (8500 t MSW)−1 linked to transportation and 190.28 GJ (8500 t MSW)−1 related to composting activities. The overall energy consumption in the composting system was determined to be 6424.77 GJ (8500 t MSW)−1. By applying DEA optimization, energy savings of 14.45 GJ (8500 t MSW)−1 were accomplished in the composting process, with a significant reduction in electricity usage contributing to these savings. The environmental impact of the energy consumption patterns identified by DEA was notably lower compared to current energy practices. The most notable decrease in impact was observed in the Photochemical Oxidation category. By following the energy usage pattern recommended by DEA, the Global Warming Potential impact reduced by 500 kg CO2 eq. per 8500 t MSW. Additionally, the optimization of energy use through DEA led to a decrease in fossil energy resource depletion by around 4 GJ (8500 t MSW)−1 in the composting process.

Assessment of Municipal Solid Waste Management Scenarios in Metro Manila Using the Long-Range Energy Alternatives Planning-Integrated Benefit Calculator (LEAP-IBC) System

Short-lived climate pollutants (SLCPs) and municipal solid wastes (MSWs) have been found to be viable sources of clean energy. This study integrates the Intergovernmental Panel on Climate Change (IPCC) guidelines for methane flow rate estimation in the software Long-Range Energy Alternatives Planning-Integrated Benefit Calculator (LEAP-IBC) system to estimate and project the methane emissions coming from the waste generated by Metro Manila, disposed in sanitary landfills. It aims to analyze the environmental impacts of the emissions coming from the non-energy sector using the IBC feature of LEAP and by developing two scenarios with 2010 and 2050 as the base and end years: the baseline and methane recovery scenario, where the latter represents the solid waste management undertaken to counter the emissions. Under the baseline, 97.30 million metric tonnes of methane emissions are expected to be produced and are predicted to continuously increase. In the same scenario, the cities of Quezon, Manila, and Caloocan account for the biggest methane emissions. On the other hand, in the methane recovery scenario, the methane emissions are expected to have a decline of 36% from 127.036 to 81.303 million metric tonnes by 2025, 52% from 135.358 to 64.972 million metric tonnes by 2030, and 54% from 150.554 to 69.254 million metric tonnes by 2040. For the 40-year projection of the study under the 100-year global warming potential analysis, a total of 10,249 million metric tonnes of CO2 equivalent is avoided in the methane recovery compared to the BAU, and a maximum of 0.019 °C temperature increase can also be avoided. Moreover, electricity costs without LFG technology increase from 2.21 trillion to 8.75 trillion, while costs with LFG technology also rise but remain consistently lower, ranging from 2.20 trillion to 8.74 trillion. This consistent reduction in electricity costs underscores the long-term value and importance of adopting LFG technology, even as its relative savings impact diminishes over time. Finally, the fixed effects and random effects panel data regression analysis reinforces and asserts that the solid waste management is really improved by means of the methane recovery technology, leading the methane emissions to decrease.