查看更多>>摘要：A systematic thermodynamics-based framework was applied to recycle waste low and high-calcium coal combustion Fly Ash (FA) into synthetic lightweight aggregates (LWA) through sintering. The process to successfully manufacture synthetic LWA was investigated, which requires a delicate balance among three phenomena: (i) sufficient liquid phase formation during sintering, (ii) appropriate viscosity for the liquid-solid phase, and (iii) sufficient amount of gas emission to form pores in the LWA. Thermodynamics modeling was used to quantify the formation of the liquid phase during sintering while the fluxing agent and the temperature change. The UrbainKalmanovitch, Browning, and Krieger-Dougherty models were used to quantify the viscosity of the liquid and liquid-solid phase, respectively. A lower bound of 100 Pass for the viscosity was found to ensure spherical shape of the LWA. Using thermogravimetric analysis, it was shown that the LWA had a notable gas release potential, owing to the presence of anhydrite and hematite, which could create gas-filled pores in the LWA macro microstructure. X-ray computed tomography (X-CT) observation revealed the formation of a porous structure for the produced LWA where high calcium FA LWA generally had larger pores compared with low calcium FA LWA. By correlating the X-CT and scanning electron microscopy (SEM) observations and thermodynamic modeling results, it was found that a minimum of 40% liquid phase content (% by mass) is necessary for the formation of gas-filled pores in FA-LWA.
查看更多>>摘要：The migration and transformation of hazardous metals in copper smelting slags (CSS) threats the environment. However, the unclear relationship between phases and heavy metals in CSS hinders the development of harmless technology. In this work, we investigated the mineralogical composition of CSS and the corresponding heavy metal distribution, and explored the relationship between mineral phases and bound heavy metals. Fayalite (47.4%) was identified as the main phase in CSS by XRD refinement along with other phases of hedenbergite (38.7%), magnetite (11.0%) and iron (2.9%). Heavy metals mainly distributed in fayalite and less in hedenbergite and other phases. The specific sequential extraction showed fayalite was difficult to extract since 89.7% arsenic, 85.0% lead and 76.9% copper were tightly bound with these minerals. It meant that fayalite had a much stronger binding ability with heavy metals than that of other phases. Fayalite could transform into magnetite during alkali disaggregation resulting in the changing of heavy metal binding from strong to weak. This work is an approximation to break through the bottleneck of phase identification and binding relationship of heavy metals in CSS, and provides novel approaches and theoretical evidence for the CSS and similar smelting slags harmfulness treatment.
Lakho, Fida HussainQureshi, AsifIgodt, WouterLe, Hong Quan...
15页
查看更多>>摘要：Decentralized (waste) water treatment technologies (DWTS) are suitable for rural areas that are not connected to conventional (municipal) treatment systems due to the longer transport distances. However, the sustainability of DWTS is still debatable. Therefore, the main goal of this study was to use the Life Cycle Assessment tool to perform the life cycle impact assessment of two different decentralized water treatment systems operated in Belgium. The first one was a mobile constructed wetland treating grey water (Scenario 1) at music festivals, coupled to a membrane based drinking water production system (100 m(3) of potable water production out of 400 m(3) of wastewater generation per festival). The second one was a vertical flow constructed wetland treating black water (Scenario 2) at a restaurant (135 visitors/day), also coupled to a membrane system. Comparison was performed with conventional alternatives (PET bottled water supply and a public drinking water supply, respectively). In most impact categories, Scenarios 1 and 2 had roughly an order of magnitude lower impact than their conventional alternatives. Sensitivity analysis was also performed. In scenario 1, the distance travelled for both the mobile constructed wetland and the PET bottles was varied. In Scenario 2 the distance of the restaurant from a drinking water supply and a sewerage system was varied. These results were also encouraging, showing that the DWTS are still environmentally feasible compared to their conventional alternatives at the shortest distance studied (Scenario 1: 175 km and Scenario 2:75 m). Therefore, DWTS can be considered environmentally beneficial under certain conditions.
查看更多>>摘要：Cities worldwide are stepping up efforts to reshape their infrastructure to ensure a carbon-neutral and sustainable future, leading to the rapid electrification of transportation systems. The electricity demand of this sector, particularly that of high-speed railways, is increasing. Application of the existing infrastructures of railway stations and available land along rail lines for photovoltaic (PV) electricity generation has the potential to power high-speed bullet trains with renewable energy and supply surplus electricity to surrounding users. In this work, a methodology based on a geographic information system was established to evaluate the PV potential along rail lines and on the roofs of train stations. The Beijing-Shanghai high-speed railway (HSR) was used as a case study. Its total PV potential reached 5.65 GW (of which the station potential accounted for 264 MW, approximately 4.68%, of the total potential), with a lifelong generation capacity of 155 TWh, which corresponds to approximately 12% of the total new installed capacity of China in 2020. Although electricity prices and solar resources differed along the railway line, all PV systems were profitable. Moreover, a comparison between the electricity consumption and generation shows that the PV-PHSR system can cover most of the electricity demand of the Beijing-Shanghai HSR without a storage system. This concept can be further expanded to other rail lines and stations. Within the context of global carbon peaks and carbon neutrality, the integration of PV and railway systems should be promoted.
查看更多>>摘要：Reprocessing and valorization of secondary resources is a possible solution to alleviate the supply-demand disparity for critical materials. The current study investigated the recovery of P and enrichment of REEs from Florida waste clay (WC). Clays, dolomite, and quartz are the main associated gangue minerals, while apatite is the predominant P-bearing mineral, and monazite and xenotime are the rare earth minerals in this WC. A 1.5-in. diam. hydro-cyclone unit was initially employed for the removal of clays. Froth flotation was then examined for the separation of values from the cyclone underflow. Various depressants and surface modifying agents were assessed for both direct and reverse flotation separations. Results showed that the direct flotation does not offer a solution for the selective recovery of P from WC. Despite their documented affinity for apatite and rare earths, hydmxamic acid collectors do not produce a selective separation. A single-stage reverse cationic process provides a more economically viable route due to its capability to avoid the loss of REEs. Test results of the single-stage reverse cationic process indicated that the P2O5 grade was increased to 21 wt.% from an initial grade of similar to 8 wt.% with a corresponding recovery of approximately 80%. The REE content was elevated from an initial value of 307.1 ppm to 800 ppm, with an 80% recovery resulting from the same process. The removal of clays, silicates, and carbonates up to a point to meet the medium-grade phosphate ore specifications also facilitates the subsequent recovery of REEs using chemical separation.
查看更多>>摘要：Microalgae-based wastewater treatment systems are one of the most promising processes to address critical challenges in both climate change and wastewater treatment. The growth of microalgae in wastewater creates feedstock for renewable energy. The wastewater medium provides the essential nutrients for the growth of microalgae, while the treated water can be recycled to reduce the cost of microalgae cultivation. It is therefore worth investigating the factors and optimal conditions of microalgal growth in wastewater systems. Using Scenedesmus quadricauda as the algal species and considering that microalgae are mostly exposed to turbulence, a self-designed oscillating grid device was used to investigate the separate effect of turbulent pulsation. Four hydraulic conditions with different turbulent intensities (turbulent dissipation rates of 0, 1.69 x 10(-3) , 1.40 x 10(-2) , 8.32 x 10(-2) m(2)s(-3)) were combined with agricultural phytohormones (a mixture of gibberellin acid, indole-3-acetic acid and brassinolide) to investigate the effects on biomass accumulation, photosynthetic properties, nutrient removal efficiency, and recycling characteristics from S. quadricauda. Results showed that moderate turbulent intensities and mixed phytohormones provided optimal operating conditions to meet nutrient removal and recycling performance. Biomass concentration and lipid yield increased by 24.78% and 70.00% respectively compared to the stationary group. The highest removal rates of 77.49% and 65.17% were achieved for ammonia nitrogen and phosphate treatments, respectively. Further, the optimum microalgal species, the appropriate nutrient profiles of wastewater and the economic value of microalgae were discussed.
查看更多>>摘要：Using social media effectively to promote green advertising is crucial for building a company's sustainability image. It is important to apply appropriate social media promotion in sustainability context to consider different factors that might be overlooked by researchers and practitioners, including the selection of celebrities in the promotion process and the way information is shared. In this paper, we address the question of how companies can achieve better customer perception regarding brand and celebrity promotion of sustainability in social media. Based on a context of plastic waste reduction propaganda, a scenario-based experiment design was employed to analyze data collected from 330 consumers. According to the results of experiments, marketers have been suggested to ensure the level of congruence between celebrity and product is high, and social media messages should be organic to achieve greater customer perceived altruism toward brands and celebrities. An analysis of structural equation models also indicates that the perceived altruism of celebrity mediates the relationship between perceived altruism of brand and intention to share information from social media. By examining the relationships between customer perceptions toward various actors of social media communication, this study contributes to the literature of marketing advertisement in the sustainability context.
查看更多>>摘要：China's carbon neutrality target before 2060 requires a significant CO2 emissions reduction for the power industry. The application of carbon capture, utilization and storage (CCUS) technology in coal-fired power plants (CFPPs) can significantly reduce the CO2 emissions while avoiding stranded assets loss; however, its contribution to carbon neutrality remains unclear. Based on a CCUS source-sink matching analysis, this paper investigates the role of CO2 emissions reduction of existing CFPPs in realizing China's carbon neutrality. This research yielded several important findings. (1) During 2020-2060, China's existing 584 CFPPs (670 GW) will totally lock in associated CO2 emissions of 60.87 Gt CO2, and have the CCUS retrofitting potential of 136-560 GW, contributing to the cumulative CO2 emissions reduction of 5.46-38.48 Gt depending on different deployment time (2025, 2030, and 2035) and maximum transport distance (100 km, 250 km, and 800 km); (2) The best window for retrofitting China's existing CFPPs is quite short and will soon be closed, because the cumulative mitigation potential will drop by 3.76-17.14 Gt (over 40%) if the deployment time is delayed by 10 years from 2025; (3) The geographical consistency of matched CFPPs and storage sites provides great opportunities for the development of CCUS clusters in Bohai Bay Basin, South Huabei Basin, Subei Basin, Songliao Basin, and Junggar Basin; (4) Jiangsu, Henan, Anhui, Hebei, Xinjiang, Heilongjiang, and Tianjin are identified as the highest priority for large-scale CCUS deployment considering that they have low-cost opportunities for CO2 transportation; (5) CFPPs in Heilongjiang, Shanxi and Jilin are more sensitive to the injection rate capacity of nearby storage sites; (6) 300 km are highly suggested to be the upper limit of transport distance especially for those CFPPs targeting deep saline aquifers (DSA) sites. This study provides low-cost CCUS opportunities for provinces and even power plants, as well as support government policymaking, especially in the appropriate length of onshore pipelines and the locations of CCUS hubs.
查看更多>>摘要：Growing public interest in environmental, social, and governance issues requires all organizations to address the United Nations Sustainable Development Goals (SDGs). Because the metals industry has been less likely to report engagement with the SDGs than other sectors, exploring its relationship with the SDGs is essential in accelerating its engagement with these goals. This study examines the relationship between the metals industry and the SDGs by analyzing reports of 61 metal companies. The analysis adopts the number of activities associated with SDGs as a proxy indicator in measuring the intensity of association between the company and 17 SDGs. The results show that the metals industry places most focus on SDGs 8, 3, and 12, but its activities are less associated with SDGs 14, 2, and 1 on the whole. Furthermore, this relationship with the SDGs shows different trends among metal producers: the steel industry places great weight on SDG 12 and less on SDGs 1 and 2, whereas the copper industry recognizes the relevance to SDGs 1 and 2. This is attributed to the different positions of the production companies in the supply chain because current SDG reporting seems to be strongly affected by the circumstances and stakeholders they face directly. For further commitment to the SDGs, these findings recommend that metal producers consider the values and benefits that the metals provide throughout the value chain. This study is of value in increasing knowledge about the metal industry's strengths and weaknesses within the SDG framework and suggests future involvement.
NSTL
Elsevier