查看更多>>摘要：Globally, governments have increased their commitment to mitigate greenhouse gas (GHG) emissions. At the same time, the compostable bioplastic market is growing rapidly as many single-use petrochemical plastics are being banned internationally. A prospective consequential life cycle assessment approach was conducted to quantify the environmental envelopes of compostable bioplastic production for the bioplastic value chains to operate within the bounds of climate neutrality. Four indicative feedstocks of (i) lignocellulosic biomass from forestry, (ii) maize biomass, (iii) food waste digestate, and (iv) food waste were evaluated for potential bioplastic production. Upstream and end-of-life emissions for these feedstocks equated to GHG balances of -16.3 to +23.5, 0.3 to 1.0, 1.0 to 4.8, and -0.1 to +0.4 kg CO2 eq. per kg bioplastic, respectively. The scenarios demonstrated that indirect land-use change could have a considerable negative impact on the environmental performance of maize-based plastic, but a positive impact, via terrestrial carbon sequestration, for lignocellulosic-derived plastic (unless increased feedstock demand drives deforestation). Appropriate use of residues and sidestreams is critical to the environmental performance of bioplastics. Efficient utilisation of residues may require decentralisation of bio-plastic production and implementation of biorefinery and circular economy concepts.
查看更多>>摘要：While material use is a vital part of human well-being and development, it is also associated with serious environmental impacts. This is cause for concern as there has been little evidence of decoupling between well-being and material use in national economies. Therefore, a detailed understanding of material use and its im-plications on socioeconomic metabolism (SEM) is required. This paper provides insights into the dynamics of material use and economic growth by quantifying the so-cioeconomic flows associated with the structural changes that affected the Portuguese economy between 1995 and 2017. We first identify different development periods based on material flow analysis and the corresponding economic structural changes. Their impacts on the socioeconomic metabolism are quantified through the analysis of monetary and physical input-output tables. Our detailed analysis has shed light on the role of each sector in material consumption across all sectors with which their activities are intertwined. We found that the Portuguese SEM went through 5 different periods in which the construction and services sectors contributed the most to the changes in the SEM. We found that, for example, despite being a high-productivity sector per se, the development of the services sector may require the support of the construction sector through the creation of infrastructures, and this affects the potential decou-pling of material use and economic growth. Understanding these dynamics is key for the creation of policies and initiatives that will lead to a more sustainable economic development and constitutes the main focus of this paper.
查看更多>>摘要：In this study, a separation process for the selective precipitation of titanium, magnesium, and aluminum from the steelmaking slag leach liquor is developed. This process involves hydroxide precipitation using a single precipitant (NaOH) to selectively recover these elements in a sulfate system without the use of other precipitants, stabilizing agents, or oxidizing/reducing agents. The systematic investigation is carried out to study the effect of several operating parameters, namely precipitation pH level, reaction temperature, stabilization time, and precipitant reagent type, on the metal recovery and product purity. After the process optimization, 83% titanium precipitate purity with 85% recovery alongside > 90% magnesium and aluminum precipitate purity with 100% recovery are achieved. The quantification and characterization of the product solids and liquors are carried out to ensure the feasibility and profitability of the developed process. For the industrial-scale operation, the mass balance of the process at a large scale is estimated. The developed process proves to be a promising technique to produce several value-added solid products including TiO2 , Al(OH)(3) , and Mg(OH)(2) from the steelmaking slag leach liquor and in turn, help close the material's life cycle.
Sanclemente Crespo, MateoVan Ginkel Gonzalez, MartaTalens Peiro, Laura
9页
查看更多>>摘要：As electric mobility gains prominence, the demand for electric vehicle batteries is rapidly rising. Although the amount of these batteries reaching their end of life is presently negligible, studies to quantify their flows and stocks will progressively gain importance as they have a high potential for reuse and contain some economic valuable materials. This study aims at forecasting the number of batteries due to be collected yearly from 2020 to 2050 in Catalonia (Northeast Spain). Product flow analyses are developed considering two different future electric vehicle sales, and two lifespan scenarios for batteries, assuming they follow a Weibull lifetime probability distribution. The volume of batteries reaching their first-use end of life will not reach significance until 2050, however strategies to optimise their use can be placed earlier to get prepared to the coming influxes. If future electric vehicle sales are to meet the Spanish Climate Change Law, influxes of batteries can increase up to 25-fold in 2030 and 72-fold in 2040. Under the extended battery service scenarios, the storage capacity is estimated to be 4 to 5 times larger than in scenarios where batteries are recycled earlier. The potential supply of secondary materials from end of life batteries will increase up to 80% of cobalt, copper and nickel, and 60% of lithium in 2050. The results urge to place proper management strategies for batteries in the coming years to help optimising their use and their potential recovery.
查看更多>>摘要：Copper slag, a byproduct of the production of copper metal, is difficult to be reused as supplementary cementitious material in the ordinary Portland cement due to the low content of active amorphous alumino-silicate and the high content of crystalline phases. This study proposes a high value-added utilization approach of copper slag to enhance the early performance of magnesium potassium phosphate cement (MPC). MPC is an expensive rapid repair material with excellent early mechanical property. The experimental results show that the addition of 40% copper slag lead to more than 30% growth of the 1 day's compressive strength of MPC mortar. The crystalline phases in copper slag, especially the fayalite (Fe2SiO4), could react and strongly increase the content of hydrates in MPC system. The reaction products of copper slag in MPC are mixtures of magnesium silicate hydrate (MSH), vivianite (Fe-3(PO4)(2)center dot 8H(2)O) and Fe-hydrotalcite (Mg4Fe2(OH)(14)center dot 3H(2)O). The novel approach proposed in this study to reuse copper slag as a reinforcing agent of MPC not only consumes solid waste but also improves the performance and reduces the cost of high-end rapid repair materials of concrete.
查看更多>>摘要：Recent times have witnessed an increasing number of countries and private firms pledging carbon neutrality by mid-century. Whilst representing a significant improvement in intentions to tackle climate change, such pledges lack substance and structure. For instance, individual pledges lack coordination and aggregation among peers, while strategies and measures to achieve ambitious targets are largely absent. Moreover, current disagreements obstructing progress in international climate change negotiations further undermine the reliability of carbon neutrality objectives. Effective international policies are needed to foster aggregate mitigation ambitions and the creation of adequate supporting mechanisms. This theoretical paper describes a governance innovation aimed at overcoming such shortfalls and disagreements through a unifying yet customizable pathway towards carbon neutrality. It does so by first outlining a political governance framework based on a climate club interpretation of Article 6 of the Paris Agreement. Secondly, it proposes carbon emission mitigation effort sharing on a per capita basis to ensure efficiency, equity and political feasibility. Thirdly, this paper describes how the supply of certified mitigations of carbon emissions required to satisfy effort sharing-based demand can be assetized as carbon credits by operationalizing Article 6 as a joint certification mechanism. The resulting governance architecture for managing demand and supply of mitigations shifts efforts to tackle climate change from a 'problem-driven' cost approach to 'opportunity-driven' value creation pathways towards carbon neutrality.
查看更多>>摘要：With cities' intertwined challenges of garbage siege and climate change, it is imperative to explore the greenhouse gas (GHG) emissions from municipal solid waste (MSW) treatment and the determinants of the emissions change. However, related quantitative analysis with high spatial resolution in China has been lacking, which hinder tailored policymaking. To fill the gap, this study develops a long time-series inventory of GHG emissions (including CH4, CO2 and N2O) from MSW for 294 Chinese prefecture-level cities. The temporal and spatial logarithmic mean divisia index (LMDI) model is further used to reveal the drivers behind the emissions change and difference. Results showed that domestic GHG emissions from MSW treatment increased from 39.24 Mt CO(2)e in 2006 to 128.81 Mt CO(2)e in 2019, 63.41%-88.95% of which were CH4 emissions accounting for 8.13%-10.22% of China's total CH4 emissions. First-tier cities and new first-tier cities (6.44%) contributed 35.44% to the national emissions in 2019. Furthermore, the national increased emissions were primarily driven by economic output (66.09%), while the MSW treatment intensity per GDP caused emissions reduction by 5.23%. The spatial decomposition verified that the population size was the dominant driving factor for differences between the national average and city-level emissions. Improvements in MSW treatment structure may be the effective abatement strategy for cities in Northwestern China (e.g., Yinchuan, Xining and Lanzhou). These findings could provide insights into the GHG emission mitigation of cities' MSW sector for a future carbon-neutral society.
查看更多>>摘要：Conversion of pervious natural ground into impermeable pavement systems has caused severe environmental impacts such as urban heat islands, increased infrastructure-related greenhouse gas (GHG) emissions and energy consumption, and runoff generation / flashfloods during rainfall events. These phenomena can be addressed with the use of pervious concrete pavement (PCP) systems, which have gained acceptance as sustainable alternatives to conventional materials. However, implementation of PCP technology is limited to low-volume roads, side-walks, and parking lots attributed to low strength and the need for high quality control during construction compared to traditional pavements along with limited understanding on the end-of-life significance due to the green PCP product. Therefore, the major objective of this research was to develop a pavement system with superior structural and hydrological performance characteristics over traditional PCP, while also quantifying the energy consumed, amount of GHG produced, and costs associated with its design and construction. Thus, a Pervious All-Road All-weather Multilayered pavement (PARAMpave) was conceptualized and designed that comprised a 300 mm square paver block created with a 60 mm lower structural layer overlaid with a 30 mm water-draining surface wearing course pervious concrete layer. The major properties of PARAMpave products included porosity ranging from 17% to 24%, permeability varying from 0.77 cm/s to 1.33 cm/s, and flexural strength between 4.83 MPa and 6.13 MPa, indicating their improved structural and hydrological performance compared to traditional designs. Further, a cradle-to-gate lifecycle approach was utilized to perform a comparative evaluation between PARAMpave and Portland cement concrete (PCC) paver blocks. The PARA-Mpave products consumed lower energy (8.22% to 8.51%) and emitted lower GHGs (8.23% to 8.43%) compared to PCC blocks of similar dimensions. Additionally, PARAMpave blocks were about 10% cheaper and almost 10% lighter than a PCC paver block. The reduction in GHG emissions, energy consumption, and capital costs indicate that PARAMpave blocks are a sustainable class of roadway products. Also, the strength and permeability mag-nitudes of PARAMpave indicate that they have high potential for applications in different road classes and diversified weather conditions.
查看更多>>摘要：The growing demand of portable as well as wearable electric devices necessitates the fabrication of energy storage devices (ESDs) in the form of flexible and wearable without sacrificing too much of their performance. In this work, a simple and efficient approach with one step recovery process of copper oxide nanoparticles (CuO NPs) from discarded printed circuit boards is reported. Further, the as-recovered CuO NPs were used as electrode material for supercapacitors (SCs). Many spectral as well as analytical techniques were used to confirm the formation of CuO NPs. The electrochemical techniques including cyclic voltammetry (CV), Galvanostatic Charge Discharge measurements (GCD) were performed to measure the specific capacitance (C-sp) of the as-fabricated electrode. As a result, the as-fabricated CuO NPs electrode delivered C-sp of 408 F g(-1) and capacitance retention of 93.1% after 3000 GCD cycles. The enhanced capacitive performance of the as-recovered CuO NPs mainly depends on the distinct structural features and abundant redox sites with high electrical conductivity. Hence, the proposed work is found to be an excellent method to recover CuO NPs and the fabrication of SCs.
Bohm, KristinHatley, Gregory A.Robinson, Brett H.Gutierrez-Gines, Maria J....
11页
查看更多>>摘要：Annually, over 30 million dry tonnes of biosolids are produced worldwide, most of which are disposed into landfills or discharged into waterbodies, exacerbating eutrophication and water-borne diseases. Bioconversion of biosolids using Black Soldier Fly larvae (BSFL) can produce high-value biomass (protein, lipids, and chitin) while reducing the volume of waste that requires disposal. We aimed to determine the bioconversion performance of BSFL on different types of biosolids and biosolids blends and analysed the bioaccumulation of heavy metals in the larvae. BSFL converted all substrates into larvae biomass of similar protein content (31-37%). However, larvae growth and substrate reduction were significantly lower for unblended biosolids compared to wheat bran. Blending of biosolids with other organic waste such as food waste or wheat bran improved larvae performance (< 40% substrate reduction after 20 days; < 149 kg larvae/ tonne dry substrate) and fat content (< 31%). Despite initial high concentrations in biosolids (< 8700 mg/ kg), heavy metals were largely partitioned into the residues instead of the mature BSFL, resulting in low bioaccumulation of those elements in BSFL (< 180 mg/ kg). These concentrations were even below limits of international guidelines for animal feed. Therefore, this study demonstrated that BSF-based bioconversion can be an innovative and sustainable waste management and resource recovery technology to rapidly reduce the volumes of biosolids while transforming it into high-value biomass of low heavy metal concentrations.
NSTL
Elsevier