Waste Disposal & Sustainable Energy最新文献

Sub-Saharan Africa is witnessing a proliferation of photovoltaic (PV) waste due to the increasing number of solar PV power plants. PV waste (panels, batteries, electrical cables, mounting structures, and inverters) consists of elements such as mercury, cadmium, chromium, lead, copper, aluminum, fluorinated compounds, and plastics that are toxic to human health and the environment if a proper management system is not available. Although many studies worldwide have focused on PV waste management, very few have been conducted in sub-Saharan Africa. This study aims to investigate the current PV waste management system in Burkina Faso, determine stakeholder profiles, and propose strategies to enhance the existing system. Documentary research, interviews, questionnaires, and field visits were used in the methodology. The survey showed that young people, mainly under 30 years of age and with a primary education, dominate (70%) in terms of PV waste collection and repair activities, while the more technical recycling and export activities are carried out mainly (88%) by stakeholders older than 40 years and with a secondary education (60%). Among the older stakeholders, 100% are aware of the hazardous nature of PV waste, whereas 36% are young people. From an environmental perspective, the main source of contamination observed is the release of lead-rich sulfuric acids into water and soil during the collection and repair phases. During the recycling of batteries and electrical cables, toxic fumes are emitted into the air, and recycling residues rich in toxic substances are landfilled. To reduce risks to human health and the environment when managing PV waste, the introduction of legislation, the multiplication of collection points and appropriate infrastructures, the training and awareness-raising of stakeholders, and the extended responsibility of manufacturers are recommended. Studies on the economic feasibility of setting up formal management structures are needed to complete this work.

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The moisture content (MC) of municipal sludge is the key factor affecting sludge treatment and disposal technologies, while the vast majority of existing measurement methods are off-line and time-consuming. To realize rapid online detection for the MC of sludge, a detection method based on the microwave reflection principle is proposed: experiments are carried out and the MC computation model of the sludge is derived using the resonant frequency and the permittivity ((varepsilon^{prime})). The results reveal that the detection accuracy of granular sludge with a thickness of 10 mm is higher. The theoretical model between the MC and the real part of (varepsilon^{prime}) is developed, and the relationship between the resonant frequency and (varepsilon^{prime}) is expressed by a cubic polynomial. The average error and the root mean square error (RMSE) of sludge are 2.06% and 2.49%, respectively. The prediction model for the MC of sludge is also given, and the determination coefficient and RMSE are 0.981 and 2.06%, respectively.

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This article has the general objective of estimating the efficiency of urban solid waste management in 940 Brazilian municipalities through Data Envelopment Analysis (DEA) technique and has specific objectives: (i) to estimate efficiency scores; (ii) to compare the performance between different groups of municipalities; and (iii) to analyze the profile of efficient municipalities from the perspective of the guidelines of Law 12,305/2010 and socio-economic and environmental indicators. The technique used was DEA with output-oriented and variable scale to return modeling. The results showed higher efficiency scores in the municipalities with populations above 500,000 inhabitants. The score variation ranged from 0.5 (municipalities with populations <10,000 inhabitants) to 0.9 (municipalities with more than 500,000 inhabitants). Of the sample set, only 12.34% of the municipalities were considered efficient, and when analyzing the efficient group, it was found that adherence to legislation was not a major factor in achieving efficiency.

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The European Union (EU) and the United States (US) determine municipal solid waste (MSW) statistics differently. The EU applies a site-specific methodology that directly measures waste whereas the US employs a materials flow methodology that estimates MSW statistics indirectly based on production and recovery data from industries. This study dissects the materials flow methodology and presents quantitative materials flow Sankey diagrams for the primary MSW materials to highlight data gaps that can be addressed to improve the methodology’s accuracy. Private industry plastics data were applied to the materials flow methodology, and the results were within 10% of the plastics statistics reported by the US Environmental Protection Agency (US EPA). Drawbacks to the methodologies include EU measurement inaccuracies due to double-counting and not accounting for residual waste in the US. The latter may partially explain why landfilling tonnages reported by the US EPA were approximately 60% less than the tonnages reported by the Waste to Energy Research and Technology Council (WTERT) in its national MSW survey that applied the EU methodology in the US. Unlike the EU, there is no US national policy that requires states to measure and report state-level waste data to the US EPA. Future improvements in US MSW statistics rely heavily on the implementation of national policies to homogenize the measurement and collection of waste data from states.

Electricity generated through coal-based Thermal Power Plants (TPPs) has played a pivotal role in shaping modern civilization, revolutionizing industries, and improving the quality of life for billions of people worldwide. These TPPs contribute to about 37%–40% of the global energy requirements. Energy production, in turn, has a direct impact on the economy of any country. Apart from this boon to humankind, these TPPs combusting coal as their primary fuel also have specific environmental impacts, the major ones being water, air, and soil pollution due to unscientific disposal of high-quantity fly ash produced yearly. If we can put this ash to good use, it may assist us in mitigating the pollution caused by it. Although there are many conventional uses of fly ash, such as a pozzolanic material in the cement industry, more pathways need to be discovered to balance the high generation quantities with consumption. Therefore, a detailed description of its use in potential geoliner applications is presented in this article. A geoliner or a landfill liner acts as a virtually impenetrable layer to mitigate the leachate penetration into the underneath subsoil and groundwater, thus preventing contamination. There are presently some studies that support the use of only fly ash in such applications. Nevertheless, the properties of the geoliners using it are not so good to significantly mitigate environmental degradation owing to its high permeability and low densification tendency. The bentonite conventionally used has limited deposits and is mined intensively for its use as a natural sealant. Their deposits must also be conserved, and an alternative material that may serve similar application benefits, like bentonite, must be selected. The desired aim can be fulfilled if we blend this combustion residue with other suitable materials (such as kaolinite clay) with low permeability. Thus, the article focuses on the possibilities of blending fly ash with different clays for geoliner construction to improve the individual properties of fly ash. This will contribute to developing a scope for future scientific research in deploying these blends in natural membrane materials for various industries. Different types of geoliners that are designed to contain the disposed-off waste are also explained in detail. Additionally, a glimpse of the global fly ash market is put forward to depict its importance for various industries in this technologically advancing world. This article profoundly observes an overall environmental management aspect regarding waste utilization.

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Population growth, waste generation, and massive waste mismanagement have led to environmental catastrophe. Management of municipal solid waste (MSW) requires an efficient and sustainable integrated system. The integrated thermal processing of MSW is one of the best waste management techniques. In this study, energy analysis of MSW is carried out based on the material and energy balance of 2000 kg wet MSW, which contains 50% leachate. Once the leachate is removed, the dry MSW is sent for carbon content enhancement in carbonization to produce MSW-based char. Thereafter, the combustion of MSW-based char provided high heat and syngas to be used in a hydrothermal process for MSW leachate treatment. The result shows that the char fuel of MSW produces a sufficient amount of energy, 13501.29 MJ (84.55%), in the form of synthetic gas by-product, which has a big potential as an energy source. The novelty of the proposed integrated thermal system is to produce 84.55% synthetic gas by-product, which is used for electricity production, cooking, food, and heat energy for industrial purposes. The proposed applications of this paper offer insightful information for policymaking regarding novel MSW techniques, which are economical, energy-efficient, and environmentally friendly. Thus, it increases the effectiveness of MSW utilization.

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Food waste generation is a pressing issue that requires urgent attention and concerted efforts worldwide. The staggering amount of food wasted each year not only wastes valuable resources but also exacerbates environmental, economic, and social challenges. Food Waste Management (FWM) consists of a complex array of criteria and sub-criteria, and treatments which seems interdependent. There is a need to evaluate the FWM with the help of important criteria and sub-criteria and treatments to address this challenge. In this study, we identified four important criteria, 21 sub-criteria, and four alternatives of FWM for the case of Malaysia using the integrated approach of literature review and expert opinions. Further, we employed the approach of Modified Fuzzy Improved Analytical Hierarchy Process (IAHP) to corroborate the interrelationships among the identified criteria and sub-criteria, and their associated treatments. This study undertakes linear normalization methods to transform data into comparable numerical values and the Geometric Mean method to handle uncertainty in human judgments. Moreover, the Centroid method is employed to convert fuzzy weights into crisp sets for ease of interpretation. The results indicate that environmental is the most essential criterion, followed by social, economic, and technical. In addition, air and water pollution is identified as the most critical sub-criteria. Black Soldier Fly is discovered as the most sustainable FWM treatment, since it performs the best while meeting all the criteria and sub-criteria assessed. Sensitivity analysis demonstrates that the outputs from the proposed method are robust and reliable. The finding suggests a proper and robust approach to help decision-makers select suitable FWM treatments to tackle various criteria and alternatives especially when handling inconsistent and uncertain judgments during evaluation.

Five common single plastics and nine different household, commercial and industrial waste plastics were processed using a three-stage (i) pyrolysis, (ii) catalytic steam reforming and (iii) water gas shift reaction system to produce hydrogen. Pyrolysis of plastics produces a range of different hydrocarbon species which are subsequently catalytically steam reformed to produce H₂ and CO and then undergo water gas shift reaction to produce further H₂. The process mimics the commercial process for hydrogen production from natural gas. Processing of the single polyalkene plastics (high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP)) produced similar H₂ yields between 115 mmol and 120 mmol per gram plastic. Even though PS produced an aromatic product slate from the pyrolysis stage, further stages of reforming and water gas shift reaction produced a gas yield and composition similar to that of the polyalkene plastics (115 mmol H₂ per gram plastic). PET gave significantly lower H₂ yield (41 mmol per gram plastic) due to the formation of mainly CO, CO₂ and organic acids from the pyrolysis stage which were not conducive to further reforming and water gas shift reaction. A mixture of the single plastics typical of that found in municipal solid waste produced a H₂ yield of 102 mmol per gram plastic. Knowing the gas yields and composition from the single plastics enabled an estimation of the yields from a simulated waste plastic mixture and a ‘real-world’ waste plastic mixture to be determined. The different household, commercial and industrial waste plastic mixtures produced H₂ yields between 70 mmol and 107 mmol per gram plastic. The H₂ yield and gas composition from the single waste plastics gave an indication of the type of plastics in the mixed waste plastic samples.

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The atomization characteristics play a key role in the highly efficient combustion of pyrolysis oil derived from waste tires. In this study, the fuel properties of tire pyrolysis oil (TPO) were initially studied, and then a high-speed camera and a phase Doppler particle analyzer were employed to characterize the atomization feature of TPO. The influence of pressure and nozzle orifice diameter on atomization characteristics such as spray angle, droplet velocity, and droplet size distribution was investigated. The results showed that TPO had a high calorific value of about 43.6 MJ/kg and a low viscosity of 3.84×10^–6 m²/s at 40 °C, which made it have the potential to be used as an alternative fuel. Higher pressure expanded the spray angle and extended the spray in both the axial and radial directions. With increasing pressure, spray angle and droplet velocity raised, and the increase in crushing effect of air reduced the Sauter mean diameter (SMD) of the droplets. To obtain proper atomization quality for combustion, the pressure is expected to be higher than 1.25 MPa. With increasing nozzle orifice diameter, droplet velocity increased, and the SMD of the droplets increased as well due to weakened crushing effect of the orifice. Therefore, the pressure must be increased to maintain the atomization quality when using a nozzle with a larger orifice. Due to the lower viscosity, the velocity and particle size distribution of TPO droplets after atomization were smaller than those of diesel droplets. The extremely small carbon black contained in TPO also contributed to the breaking of droplets and played a certain role in the size reduction of the oil droplets, but it may cause the risk of nozzle blockage. In summary, TPO showed great atomization characteristics for alternative fuel applications.

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Scientific studies have focused on environmentally friendly solutions as effective as the reuse of crop products owing to plastic-waste problems in recent years. This issue is the main driving force for upcoming academic research attempts in waste valorization-related studies. Herein, we integrated an aqua-waste, mussel shell (MS), as a bioadditive form into green thermoplastic polyurethane (TPU) green composites. Tuning of the MS surface was performed to achieve strong adhesion between composite phases. The surface functionalities of MS powders were evaluated via infrared spectroscopy and scanning electron microscopy (SEM) images. Composite samples were prepared by melt-compounding followed by injection molding techniques. It was confirmed by morphological analysis that relatively better adhesion between the phases was achieved for composites involving surface-modified MS compared to unmodified MS. Tensile strength and Young’s modulus of surface-modified MS-filled composites were found to be higher than those of unmodified MS, whereas the elongation at break shifted to lower values with MS inclusions. The shore hardness of TPU was remarkably improved after being incorporated with silane-treated MS (AS-MS). Stearic acid-treated MS (ST-MS) additions resulted in an enhancement in the thermal stability of the composites. Thermo-mechanical analysis showed that the storage moduli of composites were higher than those of unfilled TPU. ST-MS additions led to an increase in the characteristic glass transition temperature of TPU. Melt flow index (MFI) of neat TPU was highly improved after MS loading regardless of modification type. According to the wear test, surface modification of MS displayed a positive effect on the wear resistance of TPU. As the water absorption data of the composites were evaluated, the TPU/AS-MS composite yielded the lowest water absorption. The silane layer on MS inclusion promoted water repellency of composites due to the hydrophobicity of silane. The results of the biodegradation investigation demonstrated that adding unmodified and/or modified MS to the TPU matrix increased the biodegradation rate. The test results at the end of a 7-week period of biodegradation with a soft-rot fungus implied that the composite materials were more biodegradable than pure TPU. Silane modification of MS exhibited better performance in terms of the characterized properties of TPU-based composites.

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