ABSTRACT
Plastic waste pollution has grown exponentially since the 1950s. This situation was exacerbated when the volume of personal protective equipment (PPE)-based plastic waste surged after the COVID-19 pandemic. Plastic waste management such as landfills and incineration have adverse effects on the environment and human health due to the leaching of hazardous chemicals and the emission of toxic gases. Modern solutions such as biodegradable plastics and green brick technology are expensive and not well developed to valorize the current accumulation of plastic waste. This has led to the emergence of thermal degradation processes, which is faster and more realistic to solve the PPE-based plastic waste buildup. Pyrolysis and gasification systems to valorize plastic waste into hydrocarbons and fuels are discussed and compared with examples respectively. Scoping review approach is employed to conduct this study. To further increase the value of the final product of plastic waste management, the integrated pyrolysis system to upcycle plastic waste to carbon nanomaterials (CNMs) and the factors affecting the production of non-condensable gases are critically reviewed. The importance of feedstock composition, catalyst type, pyrolysis operating condition (including gas condition and temperature profiles) based on various studies is discussed. The potential and limitation of an integrated pyrolysis system are assessed from kinetic analysis, economic analysis and life-cycle assessment. This review is expected to contribute to the industrial-scale development of sustainable upcycling of plastic waste and enhance the production of desirable gas components for CNM synthesis for environmental sustainability.
ABSTRACT
The COVID-19 pandemic has created a new type of waste (surgical mask waste "WMs") that presents a major challenge now and in the future, given the strong possibilities of similar epidemics to reoccur. In order to find an effective industrial solution to the millions of WMs produced daily, this research aims to develop a new eco-friendly strategy to convert WMs into H-2-CH4-rich syngas, carbon nanoparticles (CNPs), and benzene-rich tar using an updraft gasifier system. The experiments started with the preparation of WM granules using shredding followed by granulation processes. Subsequently, the granules were processed in a lab-scale reactor with a capacity of 0.9-1 kg/h and consisted of a continuous WM feed system, a gasifier, a sampling system for syngas and tar, a ceramic filtration unit for separating the CNPs against the synthesis gas, and a burner. The gasification experiments were performed in ambient air with different air-fuel equivalence ratios (ER: 0.21, 0.25, and 0.29) and temperatures (700 degrees C, 800 degrees C, and 900 degrees C) to determine the optimal conditions that yield the maximum amount of H-2-CH4-rich syngas and CNPs with less impurities. The chemical composition and morphology of the obtained gasification products (syngas, tar, and CNPs) were observed using GC-FID, FTIR, and SEM. The results showed that the maximum production of syngas (4.29 +/- 0.16 kg/h with HHV of 3804 kJ/kg) and CNPs (0.14 +/- 0.011 kg/h) accompanied by a moderate tar rate (0.123 +/- 0.009 kg/h with HHV of 41,139.88 kJ/kg) could be obtained at 900 degrees C and ER = 0.29, while the highest H-2 (16.93 +/- 1.7 vol.%) and CH4 (10.44 +/- 0.85 vol.%) contents in syngas product were synthesized at 900 degrees C and ER = 0.19. Benzene and toluene were the major GC-FID compounds in the formulated tar product with abundance up to 25.6% and 11%, respectively. Meanwhile, gasification conditions of 900 degrees C and ER = 0.24 allowed the best morphology to be formulated for spherical-shaped CNPs with a diameter of less than 200 nm.
ABSTRACT
During the COVID-19 pandemic, more than 24 billion pieces of surgical mask waste (WM) were generated in the EU region, with an acute shortage of their management and recycling. Pyrolysis and gasification are among the most promising treatments that were proposed to dispose of WMs and convert them into pyrolysis oil and hydrogen-rich syngas. This work aimed to investigate the techno-economic analysis (TEA) of both treatments in order to assess the feasibility of scaling up. The TEA was carried out using a discounted cash flow model and its data were collected from practical experiments conducted using a fluidised bed pyrolysis reactor and bubbling fluidised bed gasifier system with a capacity of 0.2 kg/h and 1 kg/h, respectively, then upscaling to one tonne/h. The technological evaluation was made based on the optimal conditions that could produce the maximum amount of pyrolysis oil (42.3%) and hydrogen-rich syngas (89.7%). These treatments were also compared to the incineration of WMs as a commercial solution. The discounted payback, simple payback, net present value (NPV), production cost, and internal rate of return (IRR) were the main indicators used in the economic feasibility analysis. Sensitivity analysis was performed using SimLab software with the help of Monte Carlo simulations. The results showed that the production cost of the main variables was estimated at 45.4 EUR/t (gate fee), 71.7 EUR/MWh (electricity), 30.5 EUR/MWh (heat), 356 EUR/t (oil), 221 EUR/t (gaseous), 237 EUR/t (char), and 257 EUR/t (syngas). Meanwhile, the IRR results showed that gasification (12.51%) and incineration (7.56%) have better economic performance, while pyrolysis can produce less revenue (1.73%). Based on the TEA results, it is highly recommended to use the gasification process to treat WMs, yielding higher revenue. [ FROM AUTHOR] Copyright of Energies (19961073) is the property of MDPI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)
ABSTRACT
Although circular economy (CE) principles set material circularity, resource efficiency and waste recycling as priority targets to guarantee the sustainable development of future generations, the thermochemical valorisation of municipal solid waste (MSW) still plays a fundamental role in the transition towards the final CE targets. As a matter of fact, the waste-to-energy (WtE) sector allows recovering energy from waste, reducing the pressure on MSW landfills and their related potential environmental impacts;however, recovering material for further uses is not excluded in WtE options. Significant improvements have been achieved in the air pollution control of exhaust gases from direct and indirect MSW combustion during the last decades. The efforts focussed on reducing dioxin emissions especially, and this has let other substances emerge as priority pollutants (e.g., heavy metals). In addition, the location of WtE facilities in certain geographical contexts is still potentially critical from the point of view of human exposure and the related health risk;moreover, the public acceptance of WtE plants is still limited, in spite of their recent role in fighting SARS-CoV-2 risks from waste management. The purpose of the present paper is to underline the importance of implementing correct and complete health risk assessment procedures tailored to the exposed population living in the area of influence of a WtE plant. The paper will present two case studies regarding the projects of two WtE plants in a mountainous region, highlighting the critical issues that arose during the environmental impact assessment procedures. The paper will finally suggest possible options to improve the health risk assessment procedure and alternative measures to reduce the expected impacts of the WtE sector on the environment and human exposure. © 2022 WIT Press.
ABSTRACT
Elevated medical waste has urged the improvement of sustainable medical waste treatments. A bibliometric analysis is initially conducted to investigate scientific development of medical waste management to pinpoint the publication trends, influential articles, journals and countries and study hotspots. Publications on medical waste and its management sharply increased since 2020. The most influential article was written by Klemeš et al., and "Waste Management and Research” is the most productive journal. India, China, the United Kingdom, Iran and Italy have published the most works. The research spotlights have switched from "human” and "sustainable development” in 2019 to "COVID-19” and "circular economy” in 2021. Since government acts essentially in handling medical waste and controlling disease transmission, rule implementations among the abovementioned countries are summarized to seek gaps between scientific advancement and regulatory frameworks. For accomplishing a circular economy, waste-to-energy technologies (incineration, gasification, pyrolysis, plasma-based treatments, carbonization, hydrogenation, liquefaction, biomethanation, fermentation and esterification) are comprehensively reviewed. Incineration, gasification, pyrolysis and carbonization are relatively feasible methods, their characteristics and limitations are further compared. By holistically reviewing current status of medical waste research, the focal points involved in management at the policy and technical level have been highlighted to find proper routes for medical waste valorization. © 2023 by the authors.
ABSTRACT
The outbreak of COVID virus resulted not only in massive human deaths but also created huge waste disposal issues. Proper disposal of COVID waste is necessary. The conversion of these wastes into value‐added products such as syngas is beneficial to overcome energy scarcity issues. The Indian high ash coal (HAC) is nonreactive, and the co‐utilisation of HAC with these plastic wastes is advantageous to produce high‐quality syngas. In the present study, thermal treatment of overall gowns (OG) used during COVID by pyrolysis and gasification process was carried out under inert and reactive conditions with and without HAC at various operating temperatures. During pyrolysis, oil with a yield of 17% was produced under N2 conditions at 900°C, whereas a reduced oxygen content in the oil was observed (absence of C–O) under CO2 conditions. The co‐gasification of OG with high ash coal in the fuel mixture resulted in the heating value of syngas as high as 8.56 MJ nm−3. The calorific value of the syngas increases by 51.8% when OG content in the fuel mixture is increased to 20% because hydrocarbon content in syngas increases by 8.73 times. Thermogravimetric analysis showed that by adding OG, gasification initiated 35°C earlier as compared to HAC. The solid residue obtained by co‐gasification contains calcium in the form of CaO and CaCO3 due to COVID‐19 waste. The global warming potential of the syngas generated is reduced by 32% with the addition of OG to 20%. [ABSTRACT FROM AUTHOR] Copyright of Asia-Pacific Journal of Chemical Engineering is the property of John Wiley & Sons, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
ABSTRACT
Due to the COVID-19 pandemic, large amounts of medical wastes have been produced and their disposal has resulted in environmental and human health problems. This medical waste may include face masks, gloves, face shields, goggles, coverall suits, and other related wastes, such as hand sanitizer and disinfectant containers. To address this issue, the effect was investigated of gasification process parameters (type of COVID-19 medical mask based on the polypropylene ratio, pressure, steam ratio, and temperature) on hydrogen syngas and cold gas efficiency. The gasification model was developed using process modeling based on the Aspen Plus software. Response surface methodology with a 3k statistical factorial design was used to optimize the process aiming for the highest hydrogen yield and cold gas efficiency. Analysis of variance showed that both the steam ratio and temperature were significant parameters regarding the hydrogen yield and cold gas efficiency. Proposed models were constructed with very high accuracy based on their coefficient of determination (R2) values being greater than 0.97. The optimum conditions were: 65 % polypropylene in the mixture, a pressure of 1 bar, a steam ratio of 0.38, and a temperature of 900 °C, producing a maximum hydrogen yield of 40.61 % and cold gas efficiency of 81.43 %. These results supported the efficacy of the primary design for steam gasification using a mixture of plastic wastes as feedstock. The hydrogen could be utilized in chemical applications, whereas the efficiency could be used as a basis for further development of the process. © 2022 THE AUTHORS
ABSTRACT
Energy crisis and increasing rigorous management standards pose significant challenges for solid waste management worldwide. Several emerging diseases such as COVID-19 aggravated the already complex solid waste management crisis, especially sewage sludge and food waste streams, because of the increasingly large production year by year. As mature waste disposal technologies, landfills, incineration, composting, and some other methods are widespread for solid wastes management. This paper reviews recent advances in key sewage sludge disposal technologies. These include incineration, anaerobic digestion, and valuable products oriented-conversion. Food waste disposal technologies comprised of thermal treatment, fermentation, value-added product conversion, and composting have also been described. The hot topic and dominant research foci of each area are summarized, simultaneously compared with conventional technologies in terms of organic matter degradation or conversion performance, energy generation, and renewable resources production. Future perspectives of each technology that include issues not well understood and predicted challenges are discussed with a positive effect on the full-scale implementation of the discussed disposal methods. © 2022 Elsevier Ltd
ABSTRACT
Thermal plasma treatment is considered as a suitable alternative for treatment of highly-hazardous wastes such as industrial, radioactive and medical wastes. Therefore, a Plasma-Gasification-Melting (PGM) system for treatment of Chemical and Pharmaceutical Wastes (CPW) with a capacity of 1 ton/day is developed using a melting and gasification furnace equipped with two non-transferred thermal plasma torches. In this article, the whole method of chemical and pharmaceutical waste disposal is presented along with exhaust gas analysis, and slag and energy balance approach for improving the relevant technology process. It is successfully demonstrated that the thermal plasma process converts chemical and pharmaceutical wastes into harmless slag. Also, the associated emission level of air pollutants is shown to be very low. The produced synthetic gas can be used as a source of energy. (11.7 Nm3 / hr for CO and 16.4 Nm3 / hr for H2). The total power consumption of the system is 120 kW including 90 kW for thermal plasma torch and 30 kW for utilities with natural gas flow rate of 1.3 Nm3 /hr. © 2022, Islamic Azad University. All rights reserved.
ABSTRACT
Globally, the demand for masks has increased due to the COVID-19 pandemic, resulting in 490,201 tons of waste masks disposed of per month. Since masks are used in places with a high risk of virus infection, waste masks retain the risk of virus contamination. In this study, a 1 kg/h lab-scale (diameter: 0.114 m, height: 1 m) bubbling fluidized bed gasifier was used for steam gasification (temperature: 800 °C, steam/carbon (S/C) ratio: 1.5) of waste masks. The use of a downstream reactor with activated carbon (AC) for tar cracking and the enhancement of hydrogen production was examined. Steam gasification with AC produces syngas with H2, CO, CH4, and CO2 content of 38.89, 6.40, 21.69, and 7.34 vol%, respectively. The lower heating value of the product gas was 29.66 MJ/Nm3 and the cold gas efficiency was 74.55 %. This study showed that steam gasification can be used for the utilization of waste masks and the production of hydrogen-rich gas for further applications.
ABSTRACT
In the European Union (EU), the dominant technology for high-temperature thermal treatment of residual Municipal Solid Waste (i.e., the unsorted waste where source separation is performed) is the moving grate incineration. The process of combustion in this sector has been optimised thanks to the introduction of stringent criteria of operation both in the combustion chamber and in the treatment of the generated off-gas. However, the costs of treatment can be sustainable only if the tariff to be applied for the service is coherent with the average value found in the sector. The literature demonstrates that, under a capacity threshold, the grate system is out of market, thus limiting the implementation of small decentralised plants. This paper discusses the potential benefits of small-scale and decentralised thermo-chemical treatment plants replacing a single large-scale one. In addition, the present article analyses the consequences of the results of a recent survey that zoomed in on the availability of small-scale gasifiers for implementing such a strategy. The results of this analysis show that small-scale gasification is preferable to other technologies (e.g., incineration and pyrolysis) in terms of scale effect and flexibility/modularity. Compared to other thermal treatments, the local environmental impact could be reduced by converting syngas into fuels or chemicals rather than burning it for direct energy recovery. The paper also shows that small-scale gasification is able to respond to different needs in both EU and non-EU countries, like the management of progressively lower amounts of residual waste requiring treatment/management of uncontrolled dump sites.
ABSTRACT
Due to the COVID-19 pandemic, large amounts of medical wastes have been produced and their disposal has resulted in environmental and human health problems. This medical waste may include face masks, gloves, face shields, goggles, coverall suits, and other related wastes, such as hand sanitizer and disinfectant containers. To address this issue, the effect was investigated of gasification process parameters (type of COVID-19 medical mask based on the polypropylene ratio, pressure, steam ratio, and temperature) on hydrogen syngas and cold gas efficiency. The gasification model was developed using process modeling based on the Aspen Plus software. Response surface methodology with a 3k statistical factorial design was used to optimize the process aiming for the highest hydrogen yield and cold gas efficiency. Analysis of variance showed that both the steam ratio and temperature were significant parameters regarding the hydrogen yield and cold gas efficiency. Proposed models were constructed with very high accuracy based on their coefficient of determination (R2) values being greater than 0.97. The optimum conditions were: 65% polypropylene in the mixture, a pressure of 1 bar, a steam ratio of 0.38, and a temperature of 900 °C, producing a maximum hydrogen yield of 40.61% and cold gas efficiency of 81.43%. These results supported the efficacy of the primary design for steam gasification using a mixture of plastic wastes as feedstock. The hydrogen could be utilized in chemical applications, whereas the efficiency could be used as a basis for further development of the process.
ABSTRACT
Carbon-fiber-reinforced polymers (CFRPs) are increasingly used in a variety of applications demanding a unique combination of mechanical properties and lightweight characteristics such as automotive and aerospace, wind turbines, and sport and leisure equipment. This growing use, however, has not yet been accompanied by the setting of an adequate recycling industry, with landfilling still being the main management route for related waste and end-of-life products. Considering the fossil-based nature of carbon fibers, the development of recovery and recycling technologies is hence prioritized to address the environmental sustainability challenges in a bid to approach mitigating the climate emergency and achieving circularity in materials’ life cycles. To this aim, we scaled up and tested a novel semi-industrial pilot plant to pyrolysis and subsequent oxidation of uncured prepreg offcuts and cured waste of CFRPs manufacturing. The environmental performance of the process proposed has been evaluated by means of a life cycle assessment to estimate the associated carbon footprint and cumulative energy demand according to three scenarios. The scale-up of the process has been performed by investigating the influence of the main parameters to improve the quality of the recovered fibers and the setting of preferable operating conditions. The pyro-gasification process attested to a reduction of 40 kgCO2eq per kg of recycled CFs, compared to virgin CFs. If the pyro-gasification process was implemented in the current manufacturing of CFRPs, the estimated reduction of the carbon footprint, depending on the composite breakdown, would result in 12% and 15%. This reduction may theoretically increase up to 59–73% when cutting and trimming waste-optimized remanufacturing is combined with circular economy strategies based on the ideal recycling of CFRPs at end-of-life.
ABSTRACT
Microwave-driven plasma gasification technology has the potential to produce clean energy from municipal and industrial solid wastes. It can generate temperatures above 2000 K (as high as 30,000 K) in a reactor, leading to complete combustion and reduction of toxic byproducts. Characterizing complex processes inside such a system is however challenging. In previous studies, simulations using computational fluid dynamics (CFD) produced reproducible results, but the simulations are tedious and involve assumptions. In this study, we propose machine-learning models that can be used in tandem with CFD, to accelerate high-fidelity fluid simulation, improve turbulence modeling, and enhance reduced-order models. A two-dimensional microwave-driven plasma gasification reactor was developed in ANSYS (Ansys, Canonsburg, PA, USA) Fluent (a CFD tool), to create 644 (geometry and temperature) datasets for training six machine-learning (ML) models. When fed with just geometry datasets, these ML models were able to predict the proportion of the reactor area with temperature above 2000 K. This temperature level is considered a benchmark to prevent formation of undesirable byproducts. The ML model that achieved highest prediction accuracy was the feed forward neural network;the mean absolute error was 0.011. This novel machine-learning model can enable future optimization of experimental microwave plasma gasification systems for application in waste-to-energy.
ABSTRACT
The recent COVID-19 pandemic, which has hit the world, is third in the last two decades. The safety and precaution measures have led to the generation of a colossal pile of biomedical waste, including plastic waste, due to the usage of personal protective equipment kits and safety equipment that is not easily manageable. The environment and health and safety concerns for humans require biomedical waste to be treated with an outstanding treatment process that can help humanity manage it by adhering to strict environmental norms prescribed. The plasma gasification technology is the most beneficial and efficient technology for treating biomedical waste. The byproducts generated can be utilized further as valuable inputs in other industries, thus strengthening the circular economy concept. In this research paper, the applicability of plasma gasification for the treatment of biomedical waste in the present scenario has been reviewed. The feasibility and applicability of the technology in handling biomedical waste have been reviewed via various research articles in this study. Also, further steps have been suggested for the Indian scenario to make this technology commercially viable in the long run.
ABSTRACT
Usage of plastics in the form of personal protective equipment, medical devices, and common packages has increased alarmingly during these pandemic times. Though they have served as an excellent protection source in minimizing the coronavirus disease (COVID-19) spreading, they have still emerged as major environmental pollutants nowadays. These non-degradable COVID-19 plastic wastes (CPW) were treated through incineration and landfilling process, which may lead to either the release of harmful gases or contaminating the surrounding environment. Further, they can cause numerous health hazards to the human and animal populations. These plastic wastes can be efficiently managed through thermochemical processes like pyrolysis or gasification, which assist in degrading the plastic waste and also effectively convert them into useful energy-yielding products. The pyrolysis process promotes the formation of liquid fuels and chemicals, whereas gasification leads to syngas and hydrogen fuel production. These energy-yielding products can help to compensate for the fossil fuels depletion in the near future. There are many insights explained in terms of the types of reactors and influential factors that can be adopted for the pyrolysis and gasification process, to produce high efficient energy products from the wastes. In addition, advanced technologies including co-gasification and two-stage gasification were also reviewed.
ABSTRACT
This study proposes a method to valorize hazardous waste such as used COVID-19 face mask via catalytic gasification over Ni-loaded ZSM-5 type zeolites. The 25% Ni was found as an optimal loading on ZSM-5 in terms of H2 production. Among different zeolites (ZSM-5(30), ZSM-5(80), ZSM-5(280), mesoporous (m)-ZSM-5(30), and HY(30)), 25% Ni/m-ZSM-5(30) led to the highest H2 selectivity (45.04 vol%), most likely because of the highest Ni dispersion on the m-ZSM-5(30) surface, high porosity, and acid site density of the m-ZSM-5(30). The content of N-containing species (e.g., caprolactum and nitriles) in the gasification product was also reduced, when steam was used as gasifying agent, which is the source of potentially hazardous air pollutants (e.g., NOx). The increase in the SiO2/Al2O3 ratio resulted in lower tar conversion and lower H2 generation. At comparable conditions, steam gasification of the mask led to ~15 vol% higher H2 selectivity than air gasification. Overall, the Ni-loaded zeolite catalyst can not only suppress the formation of hazardous substances but also enhance the production of hydrogen from the hazardous waste material such as COVID-19 mask waste.
ABSTRACT
In terms of infection control in hospitals, especially the Covid-19 pandemic that we are living in, it has revealed the necessity of proper disposal of medical waste. The increasing amount of medical waste with the pandemic is straining the capacity of incineration facilities or storage areas. Converting this waste to energy with gasification technologies instead of incineration is also important for sustainability. This study investigates the gasification characteristics of the medical waste in a novel updraft plasma gasifier with numerical simulations in the presence of the plasma reactions. Three different medical waste samples, chosen according to the carbon content and five different equivalence ratios (ER) ranging from 0.1 to 0.5 are considered in the simulations to compare the effects of different chemical compositions and waste feeding rates on hydrogen (H2) content and syngas production. The outlet properties of a 10 kW microwave air plasma generator are used to define the plasma inlet in the numerical model and the air flow rate is held constant for all cases. Results showed that the maximum H2 production can be obtained with ER = 0.1 for all waste samples.