Economic and environmental review of Waste-to-Energy systems for municipal solid waste management in medium and small municipalities

Life Cycle Sustainability Assessment of municipal solid waste management systems: a review

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.

Regulatory compliance of PCDD/F emissions by a municipal solid waste incinerator. A case study in Sant Adrià de Besòs, Catalonia, Spain

Despite incineration is an important emission source of toxic pollutants, such as heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), it is still one of the most widely used methods for the management of municipal solid waste. The current paper summarizes the results of a 20-year follow-up study of the emissions of PCDD/Fs by a municipal solid waste incinerator (MSWI) in Sant Adrià de Besòs (Catalonia, Spain). Samples of ambient air, soils and herbage were periodically collected near the facility and the content of PCDD/Fs was analyzed. In the last (2017) survey, mean levels in soil were 3.60 ng WHO-TEQ/kg (range: 0.40-10.6), being considerably higher than the mean concentrations of PCDD/Fs in soil samples collected near other MSWIs in Catalonia. Moreover, air PCDD/F concentrations were even higher than those found in a previous (2014) survey, as they increased from 0.026 to 0.044 pg WHO-TEQ/m3. Ultimately, the PCDD/F exposure would be associated to a cancer risk (2.5 × 10-6) for the population living in the surrounding area. Globally, this information indicates that the MSWI of Sant Adrià de Besòs could have had a negative impact on the environment and potentially on public health, being an example of a possible inappropriate management for years. The application of Best Available Techniques to minimize the emission of PCDD/Fs and other chemicals is critical.

Techno-environmental analysis to valorize the secondary energy resources from refuse-derived fuel-based waste to energy plant

The present study quantifies the environmental and sustainability impacts associated with municipal solid waste management (MSWM) in India which plays a vital environmental issue in recent times. The upsurge in population has resulted in massive waste generation, leading to a concerning rise in the level of greenhouse gas (GHG) emissions. Therefore, the sustainable management of MSW has been discussed and highlights the conversion of MSW into refuse-derived fuel (RDF) to identify its potential for generating electricity in waste-to-energy (WtE) plants. The life cycle assessment (LCA) study has been done to identify and compare the environmental impacts associated with different scenarios (SC) as SC1: landfilling without energy recovery, SC2: open burning and SC3: processing of RDF in WtE plant by considering the nine impact categories from the inventory data obtained over a period of 12 consecutive months (Jan 2021-Jan 2022). The results exhibited that the global warming potential caused by emissions of GHG are in the order of SC1 (1188 kg CO2 eq) > SC2 (752 kg CO2 eq) > SC3 (332 kg CO2 eq), respectively from 1 t of MSW. It is concluded that the WtE plant can help in the reduction of environmental issues, strengthening the capacity of electricity generation and improving the aesthetic view of the city which is socially acceptable as well. Thus, WtE technology can help in achieving sustainable development goal 12 to regenerate the sustainable secondary resources for the twenty-first century and minimize global climate change.

Landfill bacteriology: Role in waste bioprocessing elevated landfill gaseselimination and heat management

This study delves into the critical role of microbial ecosystems in landfills, which are pivotal for handling municipal solid waste (MSW). Within these landfills, a complex interplay of several microorganisms (aerobic/anaerobic bacteria, archaea or methanotrophs), drives the conversion of complex substrates into simplified compounds and complete mineralization into the water, inorganic salts, and gases, including biofuel methane gas. These landfills have dominant biotic and abiotic environments where various bacterial, archaeal, and fungal groups evolve and interact to decompose substrate by enabling hydrolytic, fermentative, and methanogenic processes. Each landfill consists of diverse bio-geochemical environments with complex microbial populations, ranging from deeply underground anaerobic methanogenic systems to near-surface aerobic systems. These kinds of landfill generate leachates which in turn emerged as a significant risk to the surrounding because generated leachates are rich in toxic organic/inorganic components, heavy metals, minerals, ammonia and xenobiotics. In addition to this, microbial communities in a landfill ecosystem could not be accurately identified using lab microbial-culturing methods alone because most of the landfill's microorganisms cannot grow on a culture medium. Due to these reasons, research on landfills microbiome has flourished which has been characterized by a change from a culture-dependent approach to a more sophisticated use of molecular techniques like Sanger Sequencing and Next-Generation Sequencing (NGS). These sequencing techniques have completely revolutionized the identification and analysis of these diverse microbial communities. This review underscores the significance of microbial functions in waste decomposition, gas management, and heat control in landfills. It further explores how modern sequencing technologies have transformed our approach to studying these complex ecosystems, offering deeper insights into their taxonomic composition and functionality.

A Critical Review of Data Science Applications in Resource Recovery and Carbon Capture from Organic Waste

Municipal and agricultural organic waste can be treated to recover energy, nutrients, and carbon through resource recovery and carbon capture (RRCC) technologies such as anaerobic digestion, struvite precipitation, and pyrolysis. Data science could benefit such technologies by improving their efficiency through data-driven process modeling along with reducing environmental and economic burdens via life cycle assessment (LCA) and techno-economic analysis (TEA), respectively. We critically reviewed 616 peer-reviewed articles on the use of data science in RRCC published during 2002-2022. Although applications of machine learning (ML) methods have drastically increased over time for modeling RRCC technologies, the reviewed studies exhibited significant knowledge gaps at various model development stages. In terms of sustainability, an increasing number of studies included LCA with TEA to quantify both environmental and economic impacts of RRCC. Integration of ML methods with LCA and TEA has the potential to cost-effectively investigate the trade-off between efficiency and sustainability of RRCC, although the literature lacked such integration of techniques. Therefore, we propose an integrated data science framework to inform efficient and sustainable RRCC from organic waste based on the review. Overall, the findings from this review can inform practitioners about the effective utilization of various data science methods for real-world implementation of RRCC technologies.

Municipal solid waste treatment for bioenergy and resource production: Potential technologies, techno-economic-environmental aspects and implications of membrane-based recovery

World estimated municipal solid waste generating at an alarming rate and its disposal is a severe concern of today's world. It is equivalent to 0.79 kg/d per person footprint and causing climate change; health hazards and other environmental issues which need attention on an urgent basis. Waste to energy (WTE) considers as an alternative renewable energy potential to recover energy from waste and reduce the global waste problems. WTE reduced the burden on fossil fuels for energy generation, waste volumes, environmental, and greenhouse gases emissions. This critical review aims to evaluate the source of solid waste generation and the possible routes of waste management such as biological landfill and thermal treatment (Incineration, pyrolysis, and gasification). Moreover, a comparative evaluation of different technologies was reviewed in terms of economic and environmental aspects along with their limitations and advantages. Critical literature revealed that gasification seemed to be the efficient route and environmentally sustainable. In addition, a framework for the gasification process, gasifier types, and selection of gasifiers for MSW was presented. The country-wise solutions recommendation was proposed for solid waste management with the least impact on the environment. Furthermore, key issues and potential perspectives that require urgent attention to facilitate global penetration are highlighted. Finally, practical implications of membrane and comparison membrane-based separation technology with other conventional technologies to recover bioenergy and resources were discussed. It is expected that this study will lead towards practical solution for future advancement in terms of economic and environmental concerns, and also provide economic feasibility and practical implications for global penetration.

A review on biological methodologies in municipal solid waste management and landfilling: Resource and energy recovery

Rapid industrialization and urbanization growth combined with increased population has aggravated the issue of municipal solid waste generation. MSW has been accounted for contributing tremendously to the improvement of sustainable sources and safe environment. Biological processing of MSW followed by biogas and biomethane generation is one of the innumerable sustainable energy source choices. In the treatment of MSW, biological treatment has some attractive benefits such as reduced volume in the waste material, adjustment of the waste, economic aspects, obliteration of microorganisms in the waste material, and creation of biogas for energy use. In the anaerobic process the utilizable product is energy recovery. The current review discusses about the system for approaching conversion of MSW to energy and waste derived circular bioeconomy to address the zero waste society and sustainable development goals. Biological treatment process adopted with aerobic and anaerobic processes. In the aerobic process the utilizable product is compost. These techniques are used to convert MSW into a reasonable hotspot for resource and energy recovery that produces biogas, biofuel and bioelectricity and different results in without risk and harmless to the ecosystem. This review examines the suitability of biological treatment technologies for energy production, giving modern data about it. It likewise covers difficulties and points of view in this field of exploration.

Life cycle assessment of waste-to-hydrogen systems for fuel cell electric buses in Glasgow, Scotland

Waste-to-hydrogen (WtH) technologies are proposed as a dual-purpose method for simultaneous non-fossil-fuel based hydrogen production and sustainable waste management. This work applied the life cycle assessment approach to evaluate the carbon saving potential of two main WtH technologies (gasification and fermentation) in comparison to the conventional hydrogen production method of steam methane reforming (SMR) powering fuel cell electric buses in Glasgow. It was shown that WtH technologies could reduce CO₂-eq emissions per kg H₂ by 50-69% as compared to SMR. Gasification treating municipal solid waste and waste wood had global warming potentials of 4.99 and 4.11 kg CO₂-eq/kg H₂ respectively, which were lower than dark fermentation treating wet waste at 6.6 kg CO₂-eq/kg H₂ and combined dark and photo fermentation at 6.4 kg CO₂-eq/kg H₂. The distance emissions of WtH-based fuel cell electric bus scenarios were 0.33-0.44 kg CO₂-eq/km as compared to 0.89 kg CO₂-eq/km for the SMR-based scenario.

Techno-economic and environmental assessments for sustainable bio-methanol production as landfill gas valorization

With the regular increase in global solid waste, landfilling is intensively used for waste disposal. However, landfill gas (LFG) produced as a byproduct during waste decomposition in the landfills is a serious problem since it leads to damage to the eco-systems. Accordingly, it has been highlighted to convert LFG into other value-added chemicals. In this study, LFG utilization was studied in terms of conversion into methanol (MeOH) by considering different scenarios of LFG utilization. Techno-economic analysis and environmental assessment were performed to identify the economic feasibility and environmental impact of each case. From the economic analysis, bio-MeOH production costs of 879.16, 724.52, and 1,130.74 $ ton^-1 for case 1, 2, and 3 was estimated with the economic infeasibility, while substantial cost reduction through projected cost analysis can lead to economic competitiveness (449.52 $ ton^-1 for case 2 and 595.76 $ ton^-1 for case 3). In sequence, the quantitative environmental impacts in terms of climate change impact were 2.360, 0.835, and 0.605 kg CO₂-eq kg MeOH^-1 for cases 1, 2, and 3, respectively. Based on the results of two analyses, a multi-criteria decision analysis was conducted to investigate the acceptable case of bio-MeOH production in the economic and environmental aspects. It can be concluded that the most feasible case depends on decision-makers if only economic and environmental criteria were considered. Therefore, dry reforming and membrane separation of LFG have considerable potential for bio-MeOH production in terms of LFG utilization for high weighting of economic and environmental aspects, respectively.

Electricity Generation from Municipal Solid Waste in Nigeria: A Prospective LCA Study

Diverse opportunities and environmental impacts could occur from a potential move towards waste-to-energy (WtE) systems for electricity generation from municipal solid waste (MSW) in Lagos and Abuja, Nigeria. Given this, the purpose of this study is to use life cycle assessment (LCA) as a primary analytical approach in order to undertake a comparative analysis from an environmental impact perspective of different WtE scenarios, along with diesel backup generators (DBGs) and grid electricity. A functional unit of 1 kilowatt-hour of electricity produced was used in assessing the following environmental impact categories: abiotic depletion (fossil fuels) potential (ADP), global warming potential (GWP 100a), human toxicity potential (HTP), photochemical oxidation potential (POCP), acidification potential (AP), and eutrophication potential (EP). The overall result indicated that anaerobic digestion (AD) had the highest energy generated per one tonne of MSW processed for both Lagos (683 kWh/t) and Abuja (667 kWh/t), while landfill gas to energy (LFGTE) had the lowest for both (Lagos 171 kWh/t, Abuja 135 kWh/t). AD also had the lowest environmental impacts amongst the four WtE systems for both cities based on all the impact categories except for POCP. In contrast, LFGTE had the highest impact in all the categories except ADP and HTP. Extending the analysis to include diesel-based generators (DBG) and grid electricity saw the DBGs having the highest impact overall in ADP (14.1 MJ), HTP (0.0732 Kg, 1.4 DB eq), AP (0.0129 Kg SO2 eq), and EP (0.00313 Kg PO4 eq) and grid electricity having the lowest impact in GWP (0.497 Kg CO2 eq), AP (0.000296 Kg SO2 eq), and EP (0.000061 Kg PO4 eq). It was concluded that additional electricity supply from AD to the grid, with its potential to reduce the reliance on DBGs (worst scenario overall), would be a positive action in environmental impact terms.

Integrated AHP-TOPSIS under a Fuzzy Environment for the Selection of Waste-To-Energy Technologies in Ghana: A Performance Analysis and Socio-Enviro-Economic Feasibility Study

Energy recovery from waste presents a promising alternative for several countries, including Ghana, which has struggled with unsustainable waste treatment methods and an inadequate power supply for several decades. The current study adopts a comprehensive multi-criteria decision-making approach for the selection of an optimal waste-to-energy (WtE) technology for implementation in Ghana. Four WtE technologies are evaluated against twelve selection criteria. An integrated AHP-fuzzy TOPSIS method is applied to estimate the criteria’s weights and rank the WtE alternatives. From the AHP results, technical criteria obtained the highest priority weight, while social criteria emerged as the least important in the selection process. The overall ranking order of WtE technologies obtained by fuzzy TOPSIS is as follows: anaerobic digestion > gasification > pyrolysis > plasma gasification. The sensitivity analysis indicates highly consistent and sturdy results regarding the optimal selection. This study recommends adopting a hybrid system of anaerobic digestion and gasification technologies, as this offers a well-balanced system under all of the evaluation criteria compared to the standalone systems. The results of the current study may help the government of Ghana and other prospective investors select a suitable WtE technology, and could serve as an index system for future WtE research in Ghana.

Urban biowaste integrated management based on synergy mechanism and multi-objective optimization: A case study in Suzhou, China

Urban biowaste is the organic fraction of municipal solid waste (MSW) and is a predominant waste type in low- and middle-income countries. Urban biowaste is the main cause of pollution and produces odor and leachate, and it could also serve as a source of energy and nutrient elements. Therefore, urban biowaste management should actuate minimal pollution, maximized resource utilization, and economic feasibility, which makes it a multi-objective problem. With increasing requirements for the classified management of MSW, the complexity of urban biowaste management is increasing, and it is necessary to consider the synergy mechanism between different wastes and technologies from a systematic perspective. We constructed urban biowaste management integrated model (UBMIM) to support urban biowaste management system design and policy formation. Firstly, a dynamic quantitative simulation of the numerical matching and influence conduction was conducted based on technology system synergy mechanism. Secondly, a multi-objective evaluation of the technology system was conducted based on material flow analysis, life cycle assessment, and project economic benefit assessment. On this basis, a multi-objective optimization algorithm was used for technology selection under high-dimensional objectives, and the long-term risks were identified and policy recommendations were made based on an uncertainty analysis algorithm. As a case study for the application research of the model, Suzhou, China, was selected, and integrated technology solutions and policy suggestions were provided for 2020 and 2025. The optimized solution can improve the system's efficiency of energy-saving and emission reduction by 14.5%-400.9% while reducing operating costs and new investments.

Study on Preparation of Polymer-Modified Bentonite and Sand Mixtures Based on Osmotic Pressure Principle

Polymer-modified bentonite and sand mixtures (PMBS) are widely used in the engineering field due to their low cost and low permeability. In this study, different ionic types of polyacrylamides were used to modify bentonite to improve its swelling properties and impermeability. The physicochemical properties of polymer-modified bentonite were characterized by X-ray diffraction, particle size distribution, IR spectroscopy, SEM, and free swell index (FSI) to further demonstrate the successful organic modification of bentonite. To investigate the impermeability mechanism of PMBS from the perspective of osmotic pressure, the colloidal osmotic pressure of bentonite and hydraulic conductivity were compared. The results showed that anionic polyacrylamide (APAM) had the most obvious improvement on the swelling properties of bentonite, and 3% APAM increased the FSI of bentonite from 15 mL/2 g to 41 mL/2 g. With the increase in polymer dosage, the colloidal osmotic pressure of bentonite increased and the hydraulic conductivity of PMBS decreased significantly. The interior of PMBS is equivalent to a highly concentrated bentonite–sand–water system. When the colloidal osmotic pressure in the restricted space is higher than the external hydraulic pressure, it will prevent infiltration from occurring. When the external hydraulic pressure exceeds the high concentration of bentonite colloid osmotic pressure, the hydraulic conductivity may increase rapidly. Therefore, the impermeability of PMBS depends on the colloidal osmotic pressure of bentonite. Finally, it was confirmed that PMBS had a self-healing capacity by simulating damage to PMBS.

Public Expenses and Investment in Environmental Protection and Its Impact on Waste Management

The growing environmental problems with a global impact on the quality of the environment require increasing attention from all countries and the urgent adoption and implementation of established measures to protect the environment. The presented contribution points to the necessity of financial resources in the process of improving the environment. It aims to analyze public expenditures and investments spent on the environment in the European Union and the Slovak Republic, and to identify the main environmental areas to which funds flow. The aim is to assess the effectiveness of the funds spent in relation to selected indicators focused on waste management. After the analysis of the state and development of public expenditures and investments and the analysis of the methods of municipal waste management, the contribution results in the search for dependence between public expenditures and the materially and energetically recovered amount of municipal waste.

Nonlinear impact of municipal solid waste recycling and energy efficiency on environmental performance and economic growth: evidence from non-parametric causality-in-quantiles

Waste recycling significantly contributes to reducing carbon emissions and other greenhouse gases, leading to enhanced environmental performance and safeguards natural resources. Therefore, this study examines municipal solid waste recycling and energy efficiency's impact on the environmental performance and economic well-being of the USA. Some studies have emphasized the usefulness of MSW and its indicators, but most of them are survey-based and illustrate the scientific process of disposing of waste. Hence, the study intends to analyze the connection among considered variables using the recently developed and advanced estimation procedure of nonparametric causality in quantile approach by analyzing the quarterly dataset for 1990(Q1) till 2018(Q4). Through this technique, we have examined the causal relationships in different quantiles. The causality-in-quantile outcome indicates the acceptance of the null hypothesis in different quantiles, especially at low and high tail quantiles, while at some quantiles, the null hypothesis rejection is highlighted. This study suggests valuable implications for future studies, government, environmentalists, and policymakers.

Environmental sustainability of an integrate anaerobic digestion-composting treatment of food waste: Analysis of an Italian plant in the circular bioeconomy strategy

In light of the adoption of recent global policies and strategies for a more sustainable food waste management system and a greater control of environmental impacts, this study describes a circular bioeconomy plant model, currently operating in South Italy, for treatment and enhancement of organic fraction of municipal solid waste. The key basis for plant activity is dry anaerobic digestion of separately collected organic fraction of municipal solid waste (SC-OFMSW) followed by digestate composting process. Biomethane for use in the transport sector is obtained by biogas cleaning and upgrading, while high-quality compost for organic farming is produced by digestate composting. Plant activities are completed by the transformation of part of the produced waste into refuse derived fuel (RDF) to be allocated to waste-to-energy plants and the treatment of odour emissions which allows the recovery of ammonium sulphate as a fertilizer. A rooftop photovoltaic system supplies most of electric energy needed by the plant. For plant activities relative to 2020, carbon footprint was equal to -112 kg CO₂eq. for Mg of organic waste, while depletion of fossil resources was estimated at -89.6 kg oil eq. Mg^-1 of waste. Primary energy demand of food waste treatment system was -2.66 GJ Mg^-1 of input waste. Replacement of natural gas with biomethane for transport sector provided the greatest improvement contribution for all the examined categories.

Waste to energy spatial suitability analysis using hybrid multi-criteria machine learning approach

Municipal solid waste is typically managed in developing countries through various disposal methods, such as sanitary landfills or dumpsites. Alternatively, waste to energy (WTE) systems have been recently adopted to provide sustainable waste management and diversify the energy mix. The abundance of remotely sensed datasets and derivatives, along with the rapid development of artificial intelligence, can offer an effective solution for WTE site selection. In this study, an analytical hierarchy process (AHP)-based framework supported by multiple machine learning algorithms (gradient boosted tree (GBT), decision tree (DT), and support vector machines (SVMs)) was established to explore the optimum location for WTE facilities. Various social, legal, environmental, economic, morphological, and land cover parameters were considered under 11 thematic geospatial raster layers. The proposed framework was applied to the 1.5-million-capita city of Sharjah, United Arab Emirates. A novel approach was developed to incorporate Gaussian dispersion modeling for the expected air pollution emissions from a WTE facility. The results showed that the accuracy performance sequence of the algorithms was 94.6, 93.9, and 91.8% for GBT, DT, and SVM, respectively. It was found that the distance from existing landfills had the most critical impact on the optimum location of the WTE facility, followed by the distance from coastline and elevation. The AHP consistency check revealed an acceptable overall criteria consistency index and the ratio of 0.0344 and 0.019, respectively. The results showed that 16.6% of Sharjah was considered extremely highly suitable areas. This research supports decision-makers in developing local guidelines for siting WTE facilities and determining the most suitable locations for such projects.

Advances of waste management practices in India and China along with bibliometric assessment of their research outcomes

This paper presents the progress made by India and China in the field of waste management and its disposal since l996 to 2020. To access it, bibliometric analysis has been carried out using SCOPUS linked SCImago electronic database. Different bibliometric indicators such as documents, citable documents, external and self-citations, and external and self-citations per document along with their annual corresponding growth (ACG) have been calculated in order to explore the progresses made in both the countries. China has contributed 16.3% and India 4.3% to the total documents produced worldwide during 1996-2020 in waste management with the average ACG of 26.42% and 15.37%, respectively, during the same time span. Also, the average ACG for self-citations of published research documents is more than that of external citations for both the countries. In addition to that, the average self-citation magnitude reported for China (28,475) is more than that of India (5223), whereas this trend reverses in the case of average external citation per document with values 16.9 and 28.94, respectively. Moreover, the waste management practices being followed in both countries have also been compared and also presented so that it could be beneficial for the country which is relatively not good in the same.

Energy, environmental, resource recovery, and economic dimensions of municipal solid waste management paths in Mexico city

Growing municipal solid waste (MSW) generation is a source of environmental, economic, and social concerns, especially in developing world megacities where poor MSW practices prevail. Mexico City (CDMX), one of the world's largest megacities, daily produces ∼ 13,073 Mg of MSW whose management poses a tremendous challenge to local authorities and calls for additional research to conceive sound MSW strategies. This study evaluates the fossil energy use, GHG emissions, resource recovery, and economic cost dimensions of current and five alternative MSW paths in CDMX to compare their performance and identify more sustainable MSW practices for the megacity. Impacts and benefits from the MSW paths were modeled using 2018 MSW generation data, information supplied by local authorities, and literature values. Current MSW path consumes ∼ 387 MJ_fossil, generates ∼ 501 kg-CO₂e, and costs ∼ 57 USD₂₀₁₈ per Mg of MSW managed while it only valorizes < 33% of total MSW mostly via informal truck-picking. The alternative MSW paths considerably reduce GHG emissions (∼129-360 kg-CO₂e/Mg) and enhance MSW valorization (∼47-88%) though, they entail higher fossil energy consumption (447-582 MJ_fossil/Mg) and, in general, higher cost expenditures (43-208 USD₂₀₁₈/Mg). Heavy reliance on landfilling, large GHG emissions, and low MSW valorization make current MSW path in CDMX unsustainable. Incineration-based MSW paths perform better in most aspects evaluated but their high costs seem prohibitive. Results suggest MSW paths featuring open windrow composting, mechanical-biological pre-treatment, material recovery facilities, and refuse-derived fuel production may be more appropriate to improve the sustainability of CDMX MSW management.

Comparative life cycle analysis of municipal waste management systems: Kırklareli/Turkey case study

Waste-to-energy approaches are becoming increasingly important around the world, and municipal solid waste (MSW) as a renewable and sustainable energy source is of great importance to be considered in preventing climate change. On the other hand, since uncontrolled MSW is a threat to the environment and human health, sustainable municipal solid waste management should be evaluated to reduce negative environmental impacts. In this study, various municipal solid waste management options having energy production were selected and analysed by using SimaPro 9.0.0.49 to determine the most environmentally friendly waste management system. One-ton MSW in Kırklareli/Turkey was chosen as the functional unit. Environmental impacts were calculated via the CLM-IA method; impact groups were abiotic depletion, abiotic depletion (fossil fuels), global warming, ozone layer depletion, human toxicity, freshwater, marine and terrestrial ecotoxicities, photochemical oxidation, acidification and eutrophication. The first results indicated that energy recovery reduces the environmental impacts and future waste management plant of Kırklareli (material separation for recycling, biomethanisation and landfilling) is the best option within the scope of the environment at present.

Optimization of bio-oil production from microwave co-pyrolysis of food waste and low-density polyethylene with response surface methodology

The applicability of waste to energy conversion technique is facing many issues because of current waste management practices. Focusing on the segregation issue of low-density polyethylene (LDPE) from food waste (FW), microwave (MW) co-pyrolysis of FW and LDPE was investigated in this study. Multifactor optimization of the operating parameters, viz., residence time, LDPE in feed and temperature, was done with response surface methodology to achieve maximum bio-oil yield with a low total acid number (TAN). Bio-oil yield and TAN varied from 17 to 42 wt% and 16-45 mg KOH/g respectively, in various experimental runs. The optimum conditions for maximum bio-oil yield with minimum TAN were residence time -7 s, LDPE in the feed-13% and temperature - 550 °C. A quadratic model was developed to predict bio-oil yield and TAN as a function of operating parameters with an error <8.1 %. Addition of LDPE improved the bio-oil yield (by 20 %). The bio-oil also exhibited reduction in moisture content and TAN (30% and 62 %) and increase in pH and higher heating value (HHV) (40 % and 44 %). Sugars (3.09 wt%), alkanes (1.64 wt%), acids (1.07 wt%), alcohols (0.85 wt%), phenols (0.59 wt%), furans (0.58 wt%) and ketones (0.55 wt%) were the major identified compounds in the bio-oil. Thus, the high HHV and chemical composition of bio-oil indicate its potential use in boilers, engines, turbines, transportation fuels and as a renewable feed for chemical synthesis. The main mechanism for bio-oil quality improvement was the synergetic effect of FW hydrocarbon and hydrocarbon radical (^•HC) and hydrogen radical (^•H) of LDPE. The energy consumption analysis showed an energy requirement of 13.11 kWh/kg for bio-oil production.

A system dynamics-based scenario analysis of residential solid waste management in Kisumu, Kenya

The problem of solid waste management presents an issue of increasing importance in many low-income settings, including the progressively urbanised context of Kenya. Kisumu County is one such setting with an estimated 500 t of waste generated per day and with less than half of it regularly collected. The open burning and natural decay of solid waste is an important source of greenhouse gas (GHG) emissions and atmospheric pollutants with adverse health consequences. In this paper, we use system dynamics modelling to investigate the expected impact on GHG and PM_2.5 emissions of (i) a waste-to-biogas initiative and (ii) a regulatory ban on the open burning of waste in landfill. We use life tables to estimate the impact on mortality of the reduction in PM_2.5 exposure. Our results indicate that combining these two interventions can generate over 1.1 million tonnes of cumulative savings in GHG emissions by 2035, of which the largest contribution (42%) results from the biogas produced replacing unclean fuels in household cooking. Combining the two interventions is expected to reduce PM_2.5 emissions from the waste and residential sectors by over 30% compared to our baseline scenario by 2035, resulting in at least around 1150 cumulative life years saved over 2021–2035. The contribution and novelty of this study lies in the quantification of a potential waste-to-biogas scenario and its environmental and health impact in Kisumu for the first time.

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We present a system dynamics study of solid waste management in Kisumu, Kenya.

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Scenarios involve a waste-to-biogas initiative and a ban on open burning in landfill.

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Combined scenario generates 1.1m tonnes cumulative GHG savings by 2035.

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Largest contribution (42%) is from biogas substituting traditional cooking fuels.

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Combined scenario may save 1,150 cumulative life years by 2035, plus ~220 more p.a.

Life cycle assessment of sewage sludge treatment and disposal based on nutrient and energy recovery: A review

With the acceleration of urbanization, the production of urban sludge is increasing rapidly. To minimize resource input and waste output, it is crucial to execute analyses of environmental impact and assessments of sustainability on different technical strategies involving sludge disposal based on Life Cycle Assessment (LCA), which is a great potential mean of environmental management adopted internationally in the 21st century. This review aims to compare the environmental sustainability of existing sludge management schemes with a purpose of nutrient recovery and energy saving, respectively, and also to include the substitution benefits of alternative sludge products. Simultaneously, LCA research regarding the emerging sludge management technologies and sludge recycling (cement, adsorbent, bricks) is analyzed. Additionally, the key aspects of the LCA process are worth noting in the context of the current limitations reviewed here. It is worth emphasizing that no technical remediation method can reduce all environmental damage simultaneously, and these schemes are typically more applicable to the assumed local conditions. Future LCA research should pay more attention to the toxic effects of different sludge treatment methods, evaluate the technical ways of adding pretreatment technology to the 'front end' of the sludge treatment process, and further explore how to markedly reduce environmental damage in order to maximize energy and nutrient recovery from the LCA perspective.

Multi-objective optimization to improve energy, economic and, environmental life cycle assessment in waste-to-energy plant

This paper presents a multi-objective optimization (MOO) of waste-to-energy (WtE) to investigate optimized solutions for thermal, economic, and environmental objectives. These objectives are represented by net efficiency, total cost in treating waste, and environmental impact. Integration of the environmental objective is conducted using life cycle assessment (LCA) with endpoint single score method covering direct combustion, reagent production and infrastructure, ash management, and energy recovery. Initial net efficiency of the plant was 16.27% whereas the cost and environmental impacts were 75.63 €/ton-waste and -1.21 × 10⁸ Pt/ton-waste, respectively. A non-dominated sorting genetic algorithm (NSGA-II) is applied to maximize efficiency, minimize cost, and minimize environmental impact. Highest improvement for single objective is about 13.4%, 10.3%, and 14.8% for thermal, economic, and environmental, respectively. These improvements cannot be made at once since the objectives are conflicting. These findings highlight the significance role of decision makers in assigning weight to each objective function to obtain the optimal solution. The study also reveals different influence among decision variable, waste input, and marginal energy sources. Finally, this paper underlines the versatility of using MOO to improve WtE performance regarding the thermal, economic, and environmental aspects without requiring additional investment.

A Life Cycle Analysis Approach for the Evaluation of Municipal Solid Waste Management Practices: The Case Study of the Region of Central Macedonia, Greece

Municipal Solid Waste (MSW) management has been a major problem of modern cities for many years. Thus, the development of optimal waste management strategies has been a priority for the European Commission, especially in the transition toward a circular economy. In this paper, an analysis of different MSW treatment methods that can be effectively implemented in the Region of Central Macedonia (RCM) is provided, and their comparison from an environmental point of view is performed. The assessment is based on real data indicated in the recently updated Greek National Waste Management Plan, whereas the different scenarios developed include landfilling without energy recovery, landfilling with energy recovery, recycling and secondary materials recovery, mechanical-biological treatment, bio-waste composting and anaerobic digestion with energy recovery, and incineration with energy recovery. The obtained results illustrate that efficient waste streams sorting is of vital importance for the effective implementation of an integrated waste management system toward the sustainable management of MSW.

Turning waste management into a carbon neutral activity: Practical demonstration in a medium-sized European city

A Life Cycle Assessment (LCA) with focus on carbon footprint, followed by Life Cycle Costing (LCC) of municipal solid waste (MSW) management were conducted in a residential area of a medium-sized European city of 80,000 inhabitants. The initial results showed high environmental impacts and lack of economic sustainability, due to the high amounts of waste landfilled, the low extent of separate collection, low performance of mechanical-biological treatment as well as absence from alternatives to landfilling of non-recyclable materials. Taking this result as a baseline scenario, three improvement.s were tested with the aim of turning the carbon footprint of the local MSW management system into a neutral value: (i) increased separate collection of recyclables, (ii) enhanced biogas production and (iii) refuse-derived fuel (RDF) production. Successively adding the improvements, three alternative improved scenarios were defined, until reaching a negative carbon footprint, meaning that an optimised system would avoid GHG emissions. The proposed changes were sufficient to achieve carbon neutrality, as well as reduce overall environmental impacts, but were not enough for achieving economic sustainability due to the great influence of collection costs, especially for separate collection. It was concluded that by using an adequate combination of several treatment options and increasing the separate collection of recyclable materials it is possible to turn MSW management into a carbon neutral activity as well as improve its economic balance.

Economic and environmental life cycle assessment of organic waste treatment by means of incineration and biogasification. Is source segregation of biowaste justified in Germany?

In the realm of the German scope, four different waste treatment options for the Organic Fraction of Municipal Solid Waste (OFMSW) were evaluated against the environmental and economic background: (i) anaerobic digestion followed by composting, (ii) incineration of OFMSW, (iii) incineration of separately pre-dried OFMSW and (iv) a cascaded treatment system, which couples anaerobic digestion with incineration (i.e. incineration of digestate). Environmental life cycle assessment (eLCA) and a calculation of the levelized costs of exergy (LCOE) were performed to map the sustainability aspects of the different product systems. Within a hybrid approach, consisting of literature data evaluation, theoretical modelling, the conduct of lab-scaled experiments and a substrate analysis, a comprehensive assessment was compiled. Within the eLCA, the main drivers of the total environmental impact were the categories global warming potential (GWP) and the fossil depletion potential (FDP). (i) Anaerobic digestion followed by composting and (ii) incineration were hereby characterized by the fewest environmental impacts. With regards to the base case, the GWP was calculated to ~500 g CO₂-Eq/kWh exergy for these options. The FDP was <0.05 kg oil-Eq/kWh exergy for anaerobic digestion and ~0.075 kg oil-Eq/kWh exergy for incineration. The other examined treatment options were characterized by a significantly higher GWP and FDP. The economic assessment showed median LCOE of 27 ct/kWh exergy for anaerobic digestion followed by composting and thus outcompeted incineration (median: 55 ct/kWh Exergy). Separate pre-drying prior to incineration increased the economic burdens marginally. Anaerobic digestion followed by incineration showed the highest economic expenses (89 ct/kWh exergy). In conclusion, anaerobic digestion followed by composting was marked by an overall preferential environmental and economic constellation and source segregation is thereof justified and should further be maintained.

Technical description and performance evaluation of different packaging plastic waste management's systems in a circular economy perspective

The plastic waste disposal strongly raised in importance in the recent past and it is approaching a critical situation worldwide, so requiring putting in practice the criteria of circular economy by avoiding meaningless policy responses against the plastic materials. The world of plastic materials includes a wide range of goods in all the sectors of our life: packaging, construction, biomedicals, etc. The answer to the plastic waste disposal is build an industrial network characterized by reliability, flexibility, sustainability, utility in the industrial cycle and ability to provide useful products to the market. The traditional processes including recycling and energy recovery fulfil only a part of these conditions and need to be assessed in correlation to their real effect on the circular economy such as the uses of the obtained products in the anthroposphere's life cycle, the burdens generated by the processes itself, etc. Among the possible processes that can be more sustainable if compared with the traditional ones, in a real circular economy perspective, those based on thermochemical exploitation of products obtained by plastics are discussed and assessed. The results show that it is possible to transform an expensive and non-resolving plastic waste management system in an industrial network having an intrinsic economic sustainability and, overall, a well-defined role in the economic chain of plastics. The results show that an integration between the present system with the production of petrochemical products, including oil/gasoline/syngas/…, strongly improve the economic performance of the overall waste system, allowing a larger savings of not-renewable resources, a limited greenhouse burden, a release in the market of valuable products instead of poor quality materials and the minimization of waste destined to be landfilled.

Decision-Making Process in the Circular Economy: A Case Study on University Food Waste-to-Energy Actions in Latin America

Economies have begun to shift from linear to circular, adopting, among others, waste-to-energy approaches. Waste management is known to be a paramount challenge, and food waste (FW) in particular, has gained the interest of several actors due to its potential impacts and energy recovery opportunities. However, the selection of alternative valorization scenarios can pose several queries in certain contexts. This paper evaluates four FW valorization scenarios based on anaerobic digestion and composting, in comparison to landfilling, by applying a consistent decision-making framework through a combination of linear programming, Life Cycle Thinking (LCT), and Analytic Hierarchy Process (AHP). The evaluation was built upon a case study of five universities in Costa Rica and portrayed the trade-offs between environmental impacts and cost categories from the scenarios and their side flows. Results indicate that the landfill scenario entails higher Global Warming Potential and Fresh Water Eutrophication impacts than the valorization scenarios; however, other impact categories and costs are affected. Centralized recovery facilities can increase the Global Warming Potential and the Land Use compared to semi-centralized ones. Experts provided insights, regarding the ease of adoption of composting, in contrast to the potential of energy sources substitution and economic savings from anaerobic digestion.

Comparative environmental and economic life cycle assessment of high solids anaerobic co-digestion for biosolids and organic waste management

High-Solids Anaerobic co-Digestion (HS-AcD) of sewage sludge (biosolids) with the organic fraction of municipal solid waste is a promising waste management alternative due to high methane yields, lower reactor volume requirements, lower energy inputs, and less leachate production than liquid anaerobic digestion. This study evaluated the environmental and economic burdens and benefits of HS-AcD of biosolids, Food Waste (FW), and Yard Waste (YW) using Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) methods using Hillsborough County, Florida in the U.S. as a case study. Results for HS-AcD were compared with incineration, composting, and landfilling, with and without landfill gas use. The results showed that HS-AcD of a mixture of biosolids, FW, and YW had the lowest environmental impacts in all categories analyzed (global warming potential, acidification, eutrophication, and ecotoxicity). In terms of economics, HS-AcD had the lowest life cycle cost, with or without considering land acquisition. The results show that HS-AcD is the best choice to manage biosolids and the organic waste in Hillsborough County in terms of both environmental and economic sustainability.

Economic analysis of a shared municipal solid waste management facility in a metropolitan region

Municipal solid waste (MSW) management in dense urban areas is a challenge for municipalities, especially in developing countries, which commonly have deficient waste management. For example, the metropolitan region of Goiás State, Brazil, has 19 municipalities that dispose of about 72.5% of total MSW in unlicensed MSW final disposal facilities. Therefore, this study analysed the investment and operating costs, and revenues of a municipal solid waste management facility, projected for 20 years, shared among these 19 municipalities. The economic viability analysis, has shown that, regardless of the management facility type, MSW collection and transport are the most expensive cost components, accounting for about 60% of MSW management operating costs. For an Internal Rate of Return of 0%, anaerobic digestion is 11% more expensive (in total) than using community composting. For 2040 (last year), the monthly MSW management tariffs will vary between 3.5 and 10.8 R$·inhabitant^-1·month^-1, depending on the municipality. So, as the unit price of biowaste treatments lowers with waste quantities, for the municipalities with large biowaste quantities, anaerobic digestion becomes recommended for its economic attractiveness. This study can serve as a model for other municipalities in Brazil and elsewhere, helping public decision makers to establish a strategy for MSW management.

Analyses for Synthesis Gas from Municipal Solid Waste Gasification under Medium Temperatures

Municipal solid waste (MSW) gasification could be a novel method that shows the various advantages over traditional MSW treatments in China. Other research concluded that MSW gasification was operating by the assistant heat, and the gasification may occur under medium temperature. So, this study is aimed to investigate MSW gasification and pyrolysis behavior and analyze the syngas evolution and reaction mechanism. The MSW samples were collected in daily life and the experiments were carried out in a fixed tubular reactor below 650 °C. The effects of medium temperature and oxygen content on syngas quality were elucidated in depth. The results have shown that temperature can promote the syngas quality in the range of 550–650 °C, because the increasing temperature strengthens the reaction rate. The oxygen content should be controlled in a certain range, or oxidation reactions will be more prominent during gasification. The optimal gasification condition in this study was obtained at 650 °C and an oxygen concentration of 1.25%, the combustible gas yield and the lower heating value (LHV) of syngas of this condition were 0.296 L/g and 10.98 kJ/L, respectively. This study provides insights for MSW gasification under medium temperature, and a practical gasification system can be designed under a certain condition.

Review on Indian Municipal Solid Waste Management practices for reduction of environmental impacts to achieve sustainable development goals

Open dumping is a common practice for MSW disposal in most of the Indian cities, apart from the metro-cities. This practice poses significant environmental and health risks due to toxic and greenhouse gases (GHGs) emission through direct combustion and/or decay of wastes. Therefore, integrated solid waste management (ISWM) using different methods viz., incineration, composting, anaerobic digestions, refuse derived fuel, material recovery facility and sanitary landfilling, is much needed. Accordingly, three waste management case scenarios were studied for year 2001-2051 by keeping weightage of sustainable development goals 2030 of India. Case I depicts Indian present scenario of waste management where 164-735 tonnes/year of wastes would be generated for year 2001-2051. Further, 60% of waste can be treated in case II that help in reducing the land requirement up to 40% from estimated conditions of 2031 i.e., 83.8 × 10⁷ m³. The case III is most ideal waste management condition for year 2031 to reduce 80% waste hence landfill requirement would minimize up to 16.76 × 10⁷ m³ where population is at controlled conditions. This article concludes the formal handling and treatment of ISWM would minimize the landfilling, where LCA can be an antidote to achieve sustainable development goals.

Microbiology of municipal solid waste landfills: a review of microbial dynamics and ecological influences in waste bioprocessing

Municipal solid waste landfills are widely used as a waste management tool and landfill microbiology is at the core of waste degradation in these ecosystems. This review investigates the microbiology of municipal solid waste landfills, focusing on the current state of knowledge pertaining to microbial diversity and functions facilitating in situ waste bioprocessing, as well as ecological factors influencing microbial dynamics in landfills. Bioprocessing of waste in municipal landfills emanates from substrate metabolism and co-metabolism by several syntrophic microorganisms, resulting in partial transformation of complex substrates into simpler polymeric compounds and complete mineralisation into inorganic salts, water and gases including the biofuel gas methane. The substrate decomposition is characterised by evolution and interactions of different bacterial, archaeal and fungal groups due to prevailing biotic and abiotic conditions in the landfills, allowing for hydrolytic, fermentative, acetogenic and methanogenic processes to occur. Application of metagenomics studies based on high throughput Next Generation Sequencing technique has advanced research on profiling of the microbial communities in municipal solid waste landfills. However, functional diversity and bioprocess dynamics, as well as key factors influencing the in situ bioprocesses involved in landfill waste degradation; the very elements that are key in determining the efficiency of municipal landfills as tools of waste management, remain ambiguous. Such gaps also hinder progressive understanding of fundamentals that underlie technology development based on waste biodegradation, and exploration of municipal waste as a bioresource.

Vulnerability assessment of areas allocated for municipal solid waste disposal systems: a case study of sanitary landfill and incineration

This study was conducted to assess the vulnerability of areas allocated for sanitary landfill in Nakhon Ratchasima and for incineration in Phuket, Thailand, and to investigate the factors contributing to their vulnerability. Analysis was conducted to develop a vulnerability index using a composite index approach and the Intergovernmental Panel on Climate Change (IPCC) framework approach, while correlation and t tests were applied to identify the relationships and differences between the two systems. Additionally, vulnerability indices were developed using the IPCC vulnerability definition. The results suggested that the vulnerability of the areas allocated for sanitary landfill and incineration were not significantly different. The factor that had the greatest impact on the vulnerability of the sanitary landfill was nuisance, while sub-component correlation analysis revealed that cadmium in groundwater was significantly negatively correlated with vulnerability (r = - 0.958, p < 0.05). Furthermore, the factor that had the greatest effect on vulnerability from incineration was leachate. Similarly, correlation analysis suggested that the chemical oxygen demand in leachate and solid waste residues was significantly positively correlated with vulnerability (r = 0.981, 0.975 respectively, p < .05). It is hoped that these findings can be used to establish measures for preventing environmental problems, as well as to prioritize and identify issues that need to be resolved urgently, and to help policy makers select appropriate systems for different regions of Thailand.

Metals in biological tissues of the population living near a hazardous waste incinerator in Catalonia, Spain: Two decades of follow-up

During the period 1996-1998, a hazardous waste incinerator (HWI) was built in Constantí (Tarragona County, Catalonia, Spain). Because of the potential adverse effects of toxic emissions, mainly metals and dioxins and furans, waste incinerators in general have been an important cause of concern for the public opinion. For that reason, to assess its environmental impact on the surroundings, as well as the potential human health risks of the HWI, environmental and biological monitoring studies have been carried out since 1996-1998, when the baseline concentrations were established. This article summarizes all the results corresponding to metals in biological tissues of the population living near the HWI, two decades after the construction of the facility. In 1996-1998, the baseline concentrations of a number of elements (As, Be, Cd, Cr, Hg, Mn, Ni, Pb, Sn, Tl and V) were determined in samples of hair, blood and autopsy tissues (bone, brain, liver, lung and kidney) of subjects living in the area. In successive 5-year periods, new surveys were conducted to periodically measure the levels of metals in the same biological tissues. The daily dietary intake of these metals was also estimated for the population of the area. The results of this surveillance program do no suggest additional adverse health risks of metals for the population living near the HWI. However, special attention should be paid to Cr, due not only to the increases of this element observed in most analyzed biological tissues, but also in its dietary intake.

Mitigation of CO2e Emissions from the Municipal Solid Waste Sector in the Kingdom of Bahrain

Mitigating climate change to limit the global temperature increase (relative to pre-industrial temperatures) to 2 °C is receiving considerable attention around the world. Here, historical and future carbon dioxide equivalent (CO2e) emissions from municipal solid waste (MSW) in Bahrain were calculated using the revised Intergovernmental Panel on Climate Change (IPCC) 1996 and IPCC 2006 methods. The extent to which waste-to-energy (WtE) technologies can contribute to climate change mitigation was assessed by performing a multicriteria analysis. The results indicated that CO2e emissions from MSW in Bahrain have been increasing since the Askar landfill was constructed in 1986. Emission recalculations indicated that CO2e emissions from MSW contribute 6.2% of total emissions in Bahrain rather than the 11.6% reported in the second national communication. Methane emissions from MSW in 2030 are predicted to be 22–63 Gg. The WtE technologies anaerobic digestion and landfill gas recovery gave the best and gasification the worst multicriteria analysis model results. A database of WtE plants around the world should be compiled to allow decisions around the world to be based on best practices. The potential for maximizing energy recovery and decreasing costs needs to be investigated to allow WtE plants to compete better with renewable and nonrenewable energy sources.

Waste Management Analysis in Developing Countries through Unsupervised Classification of Mixed Data

The increase in global population and the improvement of living standards in developing countries has resulted in higher solid waste generation. Solid waste management increasingly represents a challenge, but it might also be an opportunity for the municipal authorities of these countries. To this end, the awareness of a variety of factors related to waste management and an efficacious in-depth analysis of them might prove to be particularly significant. For this purpose, and since data are both qualitative and quantitative, a cluster analysis specific for mixed data has been implemented on the dataset. The analysis allows us to distinguish two well-defined groups. The first one is poorer, less developed, and urbanized, with a consequent lower life expectancy of inhabitants. Consequently, it registers lower waste generation and lower C O 2 emissions. Surprisingly, it is more engaged in recycling and in awareness campaigns related to it. Since the cluster discrimination between the two groups is well defined, the second cluster registers the opposite tendency for all the analyzed variables. In conclusion, this kind of analysis offers a potential pathway for academics to work with policy-makers in moving toward the realization of waste management policies tailored to the local context.

Generating electrical energy through urban solid waste in Brazil: An economic and energy comparative analysis

The search for alternative energy sources and increasing concerns over the generation of municipal solid waste are two widely discussed themes in contemporary academic literature. A possible alternative for solving both of these problems is through electrical energy generation through the use of this waste material. Although this practice is encouraged by the Brazilian National Solid Waste Policy, energy production through such methods still requires improvement. Given these considerations, this study aims to evaluate the generation of electric energy from solid waste in three different systems (biogas from sanitary landfills; methanization of organic fraction in anaerobic digesters; and combustion in incinerators) through economic and energy analysis. Economic analysis was performed with the parameters Net Present Value and Levelized Cost of Electricity. Economic viability was only seen in the cases which considered landfill biogas energy recovery, demonstrating a need for incentives and support policies to enable technologies that are environmentally more advantageous than landfills.

An Investigation of the Feasibility of the Organic Municipal Solid Waste Processing by Coking

In the context of transition to a circular economy, one of the strategic priorities is the development of technological innovations aimed at waste processing. In this study, the foundations have been developed for a low-temperature, environmentally safe method for efficient processing of organic municipal solid waste, which may be further applied for processing both municipal and industrial waste organics in order to obtain liquid products. The maximum yield of liquid products is ensured when conducting the coking of a mixture of organic waste with long residuum in the temperature range of 400–420 °C, with a heating rate of 5–70 °C/min, and with an optimal heating time to the coking temperature of 80 min. Recommendations on the use of the waste recycling products are given. The proposed process is consistent with the principles of circular economy and does not require external energy costs because the energy needed for the process is generated by burning the gas produced during the waste coking. The process does not produce emissions into the environment and, in combination with standard refining processes, can be used to obtain commercial petroleum products.

Valorisation of the organic fraction of municipal solid waste

The appropriate selection of treatment or final disposal for municipal solid waste generated by a population depends on multiple characteristics; decision-making becomes a challenge for those responsible for its integral management. Therefore, the objective of this research was to evaluate multi-scenarios of valorisation of the organic fraction of municipal solid waste. The methodology used included a sample of 421 houses to determine the generation and composition of the aforementioned municipal solid waste; this data served as input to be able to design four treatment and final disposal scenarios: current situation, composting, anaerobic digestion and landfill. The parameters of humidity, biochemical methane potential and biogas were used. In addition, organic fraction variability and treatment cost were considered. Data analysis included design of experiments with the uncertainty coefficient and predictive equations. The results showed that composting was the scenario that presented the highest coefficient of determination and therefore it would be the best choice to fit the particular conditions of the localities. It is concluded that this applied methodology can be used as a tool in the decision-making process regarding the valorisation of the organic fraction of municipal solid waste and can be replicated at a national and international level.

Financial feasibility of waste to energy strategies in the United Arab Emirates

The present research explores the financial feasibility of alternative waste management strategies, based on waste to energy, in the United Arab Emirates. The integrated strategies assessed in this study were primarily based on anaerobic digestion (AD) or incineration. The economics of both strategies were evaluated based on various revenue and cost streams, as well as multiple financial parameters over a 20-year period. Carbon credits were estimated based on the projected carbon emission reductions from each strategy. Realistic public participation and recovery rates for waste separation and recycling were applied. It was found that the incineration strategy is profitable with a net present value of 181 million USD, compared to -127 million USD for the AD strategy. The incineration strategy was more financially favorable in terms of the payback period, internal rate of return and profitability index, mainly due to the larger amount of processed waste. On the other hand, the AD was substantially affected by the landfilling cost of the produced digestate as well as the low participation rate in the proposed food waste separation program. The levelized cost of electricity for incineration and AD was 0.096 and 0.101 USD/kWh, respectively. The incineration and AD strategies were found to breakeven at a minimum of 52.4 and 31.2 million tons of processed waste, respectively. Certain legislative and social modifications made the AD strategy financially feasible. The sensitivity analysis showed that the net present values of both strategies were strongly affected by the variations in capital investments, landfilling costs, and electricity tariff.

Thermophilic Co-Digestion of the Organic Fraction of Municipal Solid Wastes-The Influence of Food Industry Wastes Addition on Biogas Production in Full-Scale Operation

Anaerobic digestion (AD) has been used widely as a form of energy recovery by biogas production from the organic fraction of municipal solid wastes (OFMSW). The aim of this study was to evaluate the effect of the introduction of co-substrates (restaurant wastes, corn whole stillage, effluents from the cleaning of chocolate transportation tanks) on the thermophilic anaerobic digestion process of the mechanically separated organic fraction of municipal solid wastes in a full-scale mechanical-biological treatment (MBT) plant. Based on the results, it can be seen that co-digestion might bring benefits and process efficiency improvement, compared to mono-substrate digestion. The 15% addition of effluents from the cleaning of chocolate transportation tanks resulted in an increase in biogas yield by 31.6%, followed by a 68.5 kWh electricity production possibility. The introduction of 10% corn stillage as the feedstock resulted in a biogas yield increase by 27.0%. The 5% addition of restaurant wastes contributed to a biogas yield increase by 21.8%. The introduction of additional raw materials, in fixed proportions in relation to the basic substrate, increases biogas yield compared to substrates with a lower content of organic matter. In regard to substrates with high organic loads, such as restaurant waste, it allows them to be digested. Therefore, determining the proportion of different feedstocks to achieve the highest efficiency with stability is necessary.

The steam gasification reactivity and kinetics of municipal solid waste chars derived from rapid pyrolysis

Municipal solid waste treatment has been and will continue to be a major issue facing countries worldwide, and gasification has recently gained more attention as an efficient and clean technology. The steam gasification characteristics and kinetics of five different municipal solid waste chars had been investigated by the method of isothermal thermogravimetric analysis. The results showed that the gasification reactivity increased with gasification temperature. Effect of H/C and O/C ratios, ash composition and particle pore structure of chars on gasification reactivity were studied, which illustrated that the H/C and O/C ratios and ash composition had great influence on gasification reactivity and the pore structure cannot explain well in this study. A homogeneous model, unreacted shrinking core model and random pore model were employed to describe the kinetic behavior of different chars, and the kinetic parameters were also obtained. Finally, through the evaluation of the three kinetic models by comparing the experimental data with the fitted results, the random pore model was determined to perform best. This study should, therefore, be of some value to solid waste gasification industrialization.

Analysis and forecasting of municipal solid waste in Nankana City using geo-spatial techniques

The objective of this study was to analyze and forecast municipal solid waste (MSW) in Nankana City (NC), District Nankana, Province of Punjab, Pakistan. The study is based on primary data acquired through a questionnaire, Global Positioning System (GPS), and direct waste sampling and analysis. Inverse distance weighting (IDW) technique was applied to geo-visualize the spatial trend of MSW generation. Analysis revealed that the total MSW generated was 12,419,636 kg/annum (12,419.64 t) or 34,026.4 kg/day (34.03 t), or 0.46 kg/capita/day (kg/cap/day). The average wastes generated per day by studied households, clinics, hospitals, and hotels were 3, 7.5, 20, and 15 kg, respectively. The residential sector was the top producer with 95.5% (32,511 kg/day) followed by commercial sector 1.9% (665 kg/day). On average, high-income and low-income households were generating waste of 4.2 kg/household/day (kg/hh/day) and 1.7 kg/hh/day, respectively. Similarly, large-size families were generating more (4.4 kg/hh/day) waste than small-size families (1.8 kg/hh/day). The physical constituents of MSW generated in the study area with a population of about 70,000 included paper (7%); compostable matter (61%); plastics (9%); fine earth, ashes, ceramics, and stones (20.4%); and others (2.6%).The spatial trend of MSW generation varies; city center has a high rate of generation and towards periphery generation lowers. Based on the current population growth and MSW generation rate, NC is expected to generate 2.8 times more waste by the year 2050.This is imperative to develop a proper solid waste management plan to reduce the risk of environmental degradation and protect human health. This study provides insights into MSW generation rate, physical composition, and forecasting which are vital in its management strategies.

Comparative analysis of waste-to-energy alternatives for a low-capacity power plant in Brazil

The Brazilian National Solid Waste Policy has been implemented with some difficulty, especially in convincing the different actors of society about the importance of conscious awareness among every citizen and businesses concerning adequate solid waste disposal and recycling. Technologies for recovering energy from municipal solid waste were considered in National Solid Waste Policy (NSWP), given that their technical and environmental viability is ensured, being the landfill biogas burning in internal combustion engines and solid waste incineration suggested options. In the present work, an analysis of current technologies and a collection of basic data on electricity generation using biogas from waste/liquid effluents is presented, as well as an assessment of the installation of a facility that harnesses biogas from waste or liquid effluents for producing electricity. Two combined cycle concepts were evaluated with capacity in the range 4-11 MW, gas turbine burning landfill biogas and an incinerator that burns solid waste hybrid cycle, and a solid waste gasification system to burn syngas in gas turbines. A comparative analysis of them demonstrated that the cycle with gasification from solid waste has proved to be technically more appealing than the hybrid cycle integrated with incineration because of its greater efficiency and considering the initially defined guidelines for electricity generation. The economic analysis does not reveal significant attractive values; however, this is not a significant penalty to the project given the fact that this is a pilot low-capacity facility, which is intended to be constructed to demonstrate appropriate technologies of energy recovery from solid waste.