Waste Disposal & Sustainable Energy最新文献

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.

Raw biochar can be enriched with nutrients from digestates through adsorption producing nutrient-enriched biochar. The nutrient-enriched biochar can be used as a soil amendment to support sustainable agriculture. This study assessed the effect of adsorbent dose and contact time on the jackfruit waste biochar adsorption of essential nutrients of nitrogen, phosphors and potassium from the digestate. Response surface methodology (RSM) using central composite design (CCD) was utilized to optimize the adsorbent dose and contact time during the adsorption process. An adsorbent dose of 20–70 mg/g and contact time range of 48–120 h were used in this study. The optimal adsorbent dose and contact time were found to be 20 mg/g and 114.6 h, respectively. The corresponding optimum nitrogen, phosphorus and potassium adsorbed were 17.44, 20.94, and 21.36 mg/g, respectively. Models for the prediction of these values for nitrogen, phosphorus and potassium had R² values of 0.9801, 0.9804 and 0.9843, respectively, and non-significant lack of fit (p<0.05). This indicates the suitability of the models in predicting the adsorption conditions of adsorbent dose and contact time to produce high-quality nutrient-enriched biochar.

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Developing applications for the by-products obtained from waste processing is vital for resource recovery. The synthesis of ZnCl₂-activated biochar with high electrocatalytic activity was carried out by the microwave-assisted pyrolysis of pineapple peel and subsequent chemical activation process. Activated biochar is employed in the electrochemical sensing of nitrite by drop casting in a glassy carbon electrode (GCE). The activated biochar exhibited a stacked carbon sheet, 254 m² g⁻¹ Brunauer, Emmett and Teller (BET) surface area, 0.076 cm³ g⁻¹ pore volume, 189.53 m² g⁻¹ micropore area and oxygen-containing functional groups. The electrochemical impedance spectroscopy of the modified GCE showed a reduced charge transfer resistance of  61%. This is crucial to determine the electrochemical properties of biochar. The sensor showed a significant current response and an excellent limit of detection of 0.97 µmol L⁻¹. The modified-activated biochar electrochemical sensor demonstrated high selectivity, reproducibility (RSD=2.4%), and stability (RSD=2.6%).

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In the context of circular economy, it is known that once waste is generated, it should be subject to proper treatment for recovering material or energy before being disposed. Many countries worldwide, especially developing countries such as Brazil, have been struggling to effectively apply sustainable waste management in municipalities and still rely on dumpsites and unsuitable landfills. Misinformation, a weak legal framework, lack of financial resources and poor infra-structure as well as pressure from organizations profiting from the expansion of landfills are some factors contributing to the preservation of the negative status quo: the “landfill culture”. Material recovery, i.e., recycling and composting, is applied to less than 5% of Brazilian municipal waste, while 95% is disposed of in landfills or dumpsites. In this context, ABREN WtERT (Waste-to-Energy Research and Technology Council) Brazil was created in 2019 as the first permanent organization formed to promote the development of energy and material recovery from waste focused on the waste-to-energy (WTE) market. In this paper, the strategy proposed and implemented by the organization towards changing the status quo in Brazil through an integrated sustainable waste management approach is described. The proposed strategy integrates the concepts of Sustainability and Circular Economy for minimizing landfill disposal (avoiding methane emissions) and maximizing material/energy recovery. Among others, the approach focuses on changing the public opinion regarding thermal treatment facilities, mainly incinerators, which has been wrongly linked to pollution, excessive public expenditures and considered a harm to the recycling industry. The activities performed by ABREN include engaging public and private institutions, enhancing education, leading the publication of research and business studies, gathering industry members and academy experts, as well as creating strategic alliances with players around the globe. As a result, within a few years, major outcomes were achieved in Brazil, such as: (i) changes in the legal framework, (ii) launching of a specific public auction category for sponsoring electricity production from WTE facilities, and (iii) establishment of official targets for municipalities to decrease landfill disposal and increase recycling/biological treatment and energy recovery from thermal treatment. Among the national goals, it should be highlighted the target regarding the increase from zero to 994 MW of electricity production from municipal solid waste, which will require building dozens of new WTE facilities. Global outcomes are expected as well since Brazil is the seventh largest country of the globe and the most influential in Latin America. International and national business deals should thrive due to the need of operational skills and technology imports, and the avoidance of carbon emissions will positively reflect the world climate. In parallel, there is also