Waste Disposal & Sustainable Energy最新文献

Guimarães is a middle sized city and municipality located in northern Portugal. The municipality has committed to reducing the annual amount of undifferentiated municipal solid waste (MSW) from 371 kg/capita in 2021 to 120 kg/capita by 2030 under the Zero Waste Cities Certification process. In the municipality of Guimarães, one of the constant fractions of MSW composition is textile waste (TW), which the revised EU Waste Framework Directive requires separate collection by 1 January 2025. Therefore, two indicators of TW generation were analysed to identify waste collection routes with a high level of textile waste generation for the priority implementation of separate collection: TW composition in the undifferentiated MSW stream and TW generation per capita. Basic statistical analysis methods were used to process the source data of TW composition in the undifferentiated MSW stream. Cluster analysis was applied to the data set on TW generation per capita, considering the area typology (urban, rural or mixed) of collection routes. It was considered that 39% of the industrial sector of Guimarães consists of textile and clothing production and represents small- and medium-sized enterprises, which can affect TW generation in the undifferentiated MSW stream. Causal-comparative research was used to define the correlation between TW generation per capita and the economic activity of the textile and clothing industry in the municipality. As a result, applying a multi-disciplinary approach, a project of the Textile Waste Generation Map was presented.

Excessive exploitation, negligence, non-degradable nature, and physical and chemical properties of plastic waste have resulted in a massive pollution load into the environment. Consequently, plastic entres the food chain and can cause serious health issues in aquatic animals and humans. The present review summarizes currently reported techniques and approaches for the removal of plastic waste. Many techniques, such as adsorption, coagulation, photocatalysis, and microbial degradation, and approaches like reduction, reuse and recycling are potentially in trend and differ from each other in their efficiency and interaction mechanism. Moreover, substantial advantages and challenges associated with these techniques and approaches are highlighted to develop an understanding of the selection of possible ways for a sustainable future. Nevertheless, in addition to the reduction of plastic waste from the ecosystem, many alternative opportunities have also been explored to cash plastic waste. These fields include the synthesis of adsorbents for the removal of pollutants from aqueous and gaseous stream, their utility in clothing, waste to energy and fuel and in construction (road making). Substantial evidence can be observed in the reduction of plastic pollution from various ecosystems. In addition, it is important to develop an understanding of factors that need to be emphasized while considering alternative approaches and opportunities to cash plastic waste (like adsorbent, clothing, waste to energy and fuel). The thrust of this review is to provide readers with a comprehensive overview of the development status of techniques and approaches to overcome the global issue of plastic pollution and the outlook on the exploitation of this waste as resources.

Agricultural wastes are environmental hazards, as these wastes can catch fire, resulting in the loss of human and animal lives and properties. Alternatively, the wastes are dumped in large spaces, which are already limited. Cementitious composites are quasi-brittle and develop cracks at the micro and nano level, which affect their strength, durability, and esthetics. Transforming agricultural wastes to biochar and using it as fibers in cementitious materials for crack arresting and enhancing fracture toughness is an environment-friendly approach. In this research, nano to microscale carbonaceous inert fibers (biochar) of millet and maize were prepared through pyrolysis followed by ball milling. The X-ray spectroscopy (EDX) revealed that 82.08% and 86.89% of the carbon content was retained in millet and maize, respectively. The scanning electron microscope (SEM) confirmed the presence of angular, flaky, and needle-like particles in the carbonaceous inerts, which may enhance the strength and the fracture response of the cementitious materials. These inerts were added individually to mortar specimens at dosage levels of 0, 0.025%, 0.05%, 0.08%, 0.2% and 1% by mass of cement. The dispersion of the synthesized nano inerts was ensured by UV–VIS spectroscopy. The compressive strength, flexural strength, porosity, and fracture toughness of cement mortar were evaluated. The carbonized nano intrusions reduced the porosity and density of the mortar specimens. The minimum porosity was noted with 1% and 0.08% dosages of millet and maize, respectively, whereas the minimum density was observed at 1% dosage for both. An increase in compressive and flexural strengths was also noticed. The compressive strength increased by 32% and 28% with 0.2% and 0.5% millet and maize, respectively. An increase of 168% and 114% in fracture toughness was noticed at optimized dosages of 0.5% and 1% of maize and millet, respectively. It is concluded that the addition of carbonaceous inert fibers of millet and maize resulted in light-weight porous mortars with enhanced strength and fracture toughness. The fracture toughness increases with dosage as the nanoparticles enhance the tortuosity.

The dual  bag filter (DBF) system is a new polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) emission control technology that has more efficient (PCDD/Fs) removal performance,  a higher activated carbon utilization rate and less activated carbon consumption compared with the traditional single bag filter system. Moreover, few studies have been relevant to the mechanism of the PCDD/Fs removal process in the DBF system, and the selection of operating conditions of the DBF system lacks an academic basis. This study established a PCDD/Fs removal efficiency model of activated carbon injection combined bag filter (ACI+DBF) system for hazardous waste incineration flue gas and predicted  the crucial effect factors. New adsorption coefficients k₁=532,145 Nm³/(mol s) and k₂=45 Nm³/(mol s), and the relationship expression between the number of available adsorption positions of recycled AC (A_AC′) and cycle times (n) are proposed in the model. The results verify that the model error was below 5%. In addition, the PCDD/Fs removal efficiency model predicts that in a certain range, the PCDD/Fs removal efficiency increases with increasing activated carbon injection concentration. The best cycle number of activated carbon was less than 3, and the ratio of circulating activated carbon to fresh activated carbon in second bag filter (SBF) should be controlled at 7–8.

Gasification technology can effectively realize energy recovery from municipal solid waste (MSW) to reduce its negative impact on the environment. However, ammonia, as a pollutant derived from MSW gasification, needs to be treated because its emission is considered harmful to mankind. This work aims to decompose the NH₃ pollutant from MSW gasification by an in-situ catalytic method. The MSW sample is composed of rice, paper, polystyrene granules, rubber gloves, textile and wood chips. Ni–M (M=Co, Fe, Zn) bimetallic catalysts supported on sewage sludge-derived biochar (SSC) were prepared by co-impregnation method and further characterized by X-ray diffraction, N₂ isothermal adsorption, scanning electron microscopy, transmission electron microscopy and NH₃ temperature programmed desorption. Prior to the experiments, the catalysts were first homogeneously mixed with the MSW sample, and then in-situ catalytic tests were conducted in a horizontal fixed-bed reactor. The effect of the second metal (Co, Fe, Zn) on the catalytic performance was compared to screen the best Ni-M dual. It was found that the Ni–Co/SSC catalyst had the best activity toward NH₃ decomposition, whose decomposition rate reached 40.21% at 650 °C. The best catalytic performance of Ni–Co/SSC can be explained by its smaller Ni particle size that facilitates the dispersion of active sites as well as the addition of Co reducing the energy barrier for the associative decomposition of NH species during the NH₃ decomposition process. Besides, the activity of Ni–Co/SSC increased from 450 °C to 700 °C as the NH₃ decomposition reaction was endothermic.

Many growing cities of Sub-Saharan Africa (SSA) are marred by the inefficient collection, management, disposal and reuse of organic waste. The purpose of this study was to review and compare the energy recovery potential as well as bio-fertilizer perspective, from the organic waste volumes generated in SSA countries. Based on computations made with a literature review, we find that the amount of organic wastes varies across countries translating to differences in the energy and bio-fertilizer production potentials across countries. Organic wastes generated in SSA can potentially generate about 133 million GWh of energy per year. The organic waste to bio-fertilizer production potentials range from 11.08 million tons to 306.26 million tons annually. Ghana has the highest energy and bio-fertilizer potential among the SSA countries with a total per capita of 630 MWh/year and 306.26 million tons, respectively. The challenges and technical considerations for energy and bio-fertilizer approaches in the management of organic waste in SSA have also been discussed. This study is of help to the readers and strategic decision makers in understanding the contribution of bioenergy and bio-fertilizer to achieving sustainable development goals, namely, 7 (Affordable and Clean Energy) and 13 (Climate Action) in SSA.

There is a great demand for high performance rapid repair mortar (RRM) because of the wide use of cement concrete. Solid-waste-based sulfoaluminate cement (WSAC) is very suitable as a green cementitious material for repair materials because of its characteristics of high early-age strength and short setting time. However, the influence and optimization of various factors of WSAC-based RRM, such as water-to-RRM ratio, binder-to-sand ratio and additives, as well as the further solid waste replacement of aggregate, remain to be studied. This paper comprehensively studied the influence of the above factors on the performance of WSAC-based RRM and obtained a green high-performance RRM by optimizing these factors. The experimental results showed that the early and late strength of the obtained RRM is excellent, and the setting time and fluidity are appropriate, which reflected good mechanical properties and construction performance. Ordinary Portland cement (OPC) doping could not improve RRM strength. It was feasible to prepare RRM with gold tailing sand replacing part of the quartz sand. This paper provides data and a theoretical basis for the preparation of high-performance RRM based on solid waste, expanding the high value utilization of solid waste, which is conducive to the development of a low carbon society.

Renewable fuels have many advantages over fossil fuels because they are biodegradable and sustainable, and help mitigate social and environmental problems. The objective of the present study is to evaluate the performance, combustion, and emission characteristics of a compression–ignition engine using hydrogen compressed natural gas (HCNG)-enriched Kusum seed biodiesel blend (KSOBD20). The flow rate of HCNG was set at 5 L/min, 10 L/min, and 15 L/min, and the injection pressure was varied in the range of 180 bar to 240 bar. Brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC) were improved when HCNG was added to the KSOBD20. Combustion characteristics, namely, cylinder pressure (CP) and net heat release rate (NHRR), were also improved. Emissions of carbon monoxide (CO), hydrocarbons (HC), and smoke were also reduced, with the exception of nitrogen oxides (NO_x). The higher injection pressure (240 bar) had a positive effect on the operating characteristics. At an injection pressure of 240 bar, for KSOB20 + 15 L/min HCNG, the highest BTE and the lowest BSFC were found to be 32.09% and 0.227 kg/kWh, respectively. Also, the CP and NHRR were 69.34 bar and 66.04 J/°. CO, HC, and smoke levels were finally reduced to 0.013%, 47 × 10⁻⁶ and 9%, respectively, with NO_x levels at 1623 × 10⁻⁶. For optimum results in terms of engine characteristics, the fuel combination KSOBD20 + 15 L/min HCNG at FIP 240 bar is recommended.

The only proven alternative for the recovery of value from materials that cannot be recycled is waste to energy (WTE). The first part of the paper provides evidence as to the advantages of WTE over landfilling and examines the role of WTE in the urban environment. The second part of the paper is a holistic analysis of the legislative instruments used in China, that have led to the construction of nearly 400 plants from 2005 to 2019. The Chinese government was instrumental in the development of Public and Private Partnerships (PPPs), in form of Build-Operate-Transfer (BOT), or Build-Own-Operate (BOO) models with a lifetime of 20 years to 30 years. The government accepts most of the investment risk by participating in the equity structure, providing strong tax and policy incentives, and becoming fully engaged in public education and acceptance of new WTE projects. The construction and operation of these plants by the private sector had to comply with the governmental performance standards in order to receive incentives, such as an appreciable credit over the price of electricity received by coal-fired plants. The last part of this paper examines how the elements of the Chinese renewable energy and waste management laws, may be transposed to federal and state legislation for potential application in countries of the Belt and Road Initiative (BRI) region.

Iron plaque is a Fe-containing oxide film produced by the oxidation of Fe(II) in the rice root system under the combined action of oxygen infiltration and other microorganisms. Owing to its special surface structure and physio-chemical properties, the iron plaque has a strong absorption capacity for a variety of heavy metal ions. This study aimed to first investigate the effects of Fe species on the geochemical fractionation of Tl in typical paddy soil systems affected by industrial activities, followed by pot culture experiments to probe the effects of Fe species on the uptake and translocation of Tl in rice plants. The results of field work preliminarily showed that iron at different valences affected the conversion of the Tl geochemical fraction in the soil. Oxidizable Tl exerted significant positive correlation relationships with Fe²⁺ and negative correlation relationships with Fe³⁺, while reducible Tl only displayed a positive correlation with Fe³⁺. Further analysis by pot culture experiments revealed that the contents of Fe were significantly positively correlated with Tl contents in Fe plaque (R² = 0.529). In contrast, the water-soluble Tl contents in the soil were significantly negatively correlated with the contents of Fe (R² = – 0. 90, p < 0.05). It suggests that the iron plaque promoted the absorption and fixation of Tl on the root surface of rice plants, causing Tl to accumulate in the iron plaque. Besides, the Tl content in the Fe plaque on the root surface of rice plants was greater than that in the above-ground tissues, which indicates that most Fe plaque exerts a certain degree of inhibition on Tl migration into the above-ground tissues of rice plants. All these findings indicate that Fe film is also an important carrier of Tl transfer in the soil–rice plant system, which provides new scientific support for the remediation of typical Tl-contaminated rice fields.