Abiotic Depletion Potential Research Articles

Process design and mechanism analysis of reactive distillation coupled with extractive distillation to produce an environmentally friendly gasoline additive

Ethyl tert-butyl ether is a high-octane gasoline blending component with excellent performance and has important industrial application value. When ethanol and isobutylene react to form ethyl tertiary butyl ether, there is an azeotrope system of ethyl tertiary butyl ether and ethanol. The efficient production of ethyl tert-butyl ether and the precise separation of the ethyl tert-butyl ether/ethanol azeotrope are the keys to the entire process. In this work, reactive extractive distillation process and reactive extractive dividing-wall process were designed to achieve high-quality production and separation of ethyl tert-butyl ether. By analyzing the relative volatility of the solvents and combining molecular dynamics simulation and quantum chemical calculations, ethylene glycol was selected as the extractant for the separation of ethyl tert-butyl ether/ethanol. Based on the total annual cost as the objective function, three different ethyl tert-butyl ether production and separation processes were optimized and obtained the best process parameters. Finally, the whole process was analyzed from the aspects of economy, environment and exergy loss efficiency. Compared with common process, the total annual cost of reactive extractive dividing-wall process was reduced by 14.56%. The global warming potential, acidification potential and abiotic depletion potential of the reactive extractive dividing-wall process were 28.38%, 29.03%, and 28.36% lower than those of common process respectively. The exergy loss efficiency of reactive extractive dividing-wall process was reduced by 10.9%. The results showed that reactive extractive dividing-wall process has obvious economic advantages and environmental benefits and the actual production of ethyl tert-butyl ether and the separation of ethyl tert-butyl ether/ethanol azeotrope system have certain guiding significance.

Proposal of Major Environmental Impact Categories of Construction Materials Based on Life Cycle Impact Assessments.

The “Korean New Deal” policy in South Korea emphasizes the necessity of a substantial and timely response to global climate change. In addition to carbon emissions, construction materials have various environmental impacts that necessitate serious considerations. Therefore, this study aimed to identify the major environmental impact categories of construction materials that reflect their diverse environmental impact characteristics using life cycle assessment. To this end, eight environmental impact categories were assessed for seven major construction materials. The contributions of all construction materials to these environmental impact categories were then analyzed to derive major environmental impact categories with contributions ≥95% or higher for each construction material. Consequently, global warming potential and abiotic depletion potential were derived as major environmental impact categories for all seven construction materials. In the case of ready-mixed concrete and cement, the photochemical oxidant creation potential was also found to be an environmental impact category that needs to be considered further. Thus, a study that defines environmental impacts must be considered in conjunction with the carbon emissions of building materials, and presenting the criteria for evaluating the defined environmental impacts is essential.

Temporally explicit abiotic depletion potential (TADP) for mineral resource use based on future demand projections

PurposeAssessing the potential impacts (characterization) of mineral resource use in life cycle impact assessment (LCIA) has long been debated. One of the most crucial challenges in the characterization models for mineral resource use is the consideration of the changing demand and availability of in-use stocks in the future, which is relevant to the global population and economy growth as well as the increasing low-carbon technologies. We propose an extended characterization model to assess the potential impacts for arbitrary time horizons, considering future demand changes and the availability of in-use stock: temporally explicit abiotic depletion potential (TADP).MethodsThe TADP was developed based on abiotic depletion potential (ADP), which is a widely used characterization model for mineral resource use. While the ADP assesses the potential impacts of mineral resource use based on a natural stock estimate and the current extraction rate, the TADP adopts an average extraction rate for arbitrary time horizons. The average extraction rate was estimated using material flow analysis considering future demand changes and recycling under the five shared socioeconomic pathways (SSPs). TADPs were calculated for six common metals: aluminum, copper, iron, lead, nickel, and zinc.Results and discussionAs a result of calculating TADPs for the term by 2050 (TADP2050), compared to iron, all other metals showed larger values of characterization factors for all SSPs than the original ADPs. The TADP2050 of copper exhibited the largest difference with ADP among the six metals (approximately 1.9 times), which is mainly attributed to future demand growth. On the other hand, for the longer time perspective, the TADP2100 of lead and zinc exhibited larger differences with ADP than copper (approximately 2.8 times for zinc), which is mainly due to a relatively shorter lifetime for lead and a lower recycling rate for zinc. This suggests that the relative significance of the characterization factors of metals varies depending on the temporal perspective.ConclusionsWith the proposed characterization model, the potential impacts of mineral resource use can be assessed reflecting future situations for the selected time horizons. The results demonstrate that the consideration of future situations greatly influences the relative significance of the potential impacts of using different mineral resources in the results of LCIA studies. By expanding the coverage of mineral resources and future scenario analysis to other relevant factors, the TADP model can improve the robustness of the assessment and further support decision-making towards sustainable resource management.

Bioenergy from anaerobic digestion plants: Energy and environmental assessment of a wide sample of Italian plants

This study assesses the energy and environmental performances of electricity produced from Italian anaerobic digestion coupled with combined heat and power plants. The Life Cycle Assessment methodology is applied to a set of plants characterised by different power sizes (from 100 to 999 kW) and feedstock compositions (variable rates of agricultural products and by-products). Then, the average eco-profile of the produced electricity is compared with electricity produced by the national grid and photovoltaic panels.The analysis allows detection of the combinations of size and feedstock with the lowest impacts. They correspond to small and medium plants mainly fed by organic by-products.In addition, compared to electricity from the grid, the average biogas electricity is characterised by the lowest contribution in impacts categories, such as abiotic depletion potential and ozone layer depletion potential, while largest in acidification and eutrophication. Focusing on global warming potential and cumulative energy demand fossil, the impacts of average biogas electricity (155 kgCO2eq/MWh and 172 MJ/MWh) are about 35 % and 38 % of that generated by the grid. Furthermore, it could generate 47 % less of the impact in the abiotic depletion elements category of the solar system.To enhance the farms' environmental and economic sustainability and balance the electric grid, these outcomes point out that biogas electricity produced from the agriculture and livestock sector can contribute to the decarbonisation and self-sufficiency of European countries.The results strictly depend on the operative conditions and can aid policymakers at the global level in improving the energy supply security and sustainability. Further, they provide reliable information to stakeholders to select the most sustainable solution, according to the feedstock type, power supply, and management.

Life-cycle assessment approach for municipal solid waste management system of Delhi city

The life-cycle assessment (LCA) approach with route optimization technique was adopted in the present study to evaluate environmental and economic aspects associated with the prevalent waste management system in Delhi city. With an objective of cost minimization and abating environmental hazards from waste transportation systems, ArcGIS was used to identify the most appropriate route for waste transportation. The study was conducted considering four landfills located at Bawana, Bhalswa, Ghazipur and Okhla present in Delhi city. Landfilling, composting, anaerobic digestion, and recycling methods were analyzed for global warming potential (GWP), eutrophication potential (EP), acidification potential, abiotic resource depletion potential and photochemical oxidation potential parameters using LCA software GaBiPro. The results from the LCA studies for the municipal solid waste management system of Delhi city revealed that transportation emissions and landfilling negatively impact the environment. The effect of recycling rate on the landfilling, composting, anaerobic digestion was also studied using sensitivity analysis. Results of sensitivity analysis depicted that recycling of waste is inversely related to the impact categories. Overall, the results exhibited a detrimental effect of landfilling on the environment in terms of GWP and EP. Further, considering the geospatial analysis, two waste recycling stations are proposed in the vicinity of existing waste management plants to reduce the time and cost of waste transport from the landfills to the waste management plants.

Environmental Performance and Operational Analysis of a Sewage Sludge Fermentation Solid Oxidation Fuel Cell System Using Fe<sub>2</sub>O<sub>3</sub> and Kanuma Clay

This study discussed the performance of an integrated indirect gasification solid oxidation fuel cell (IIG-SOFC) in consideration of LCA thinking. Generally, hydrogen sulfide (H2S) in gasified biomass causes cell voltage in a stack to decline over time. Although the biomass resource such as sewage sludge are carbon-neutral, a decline in SOFC performance creates environmental disadvantage of global warming potential (GWP); as such, it is necessary to remove H2S via adsorption, and typically, ferric oxide (Fe2O3) is used for desulfurization. However, Fe2O3 imposes a considerable environmental burden of abiotic depletion potential (ADP). Kanuma clay (Kc) which is a natural sorbent was proposed as a viable substitute in our previous study, but Kc is characterized by a low adsorption capacity. As such, limitations associated with the adsorption column size and frequency with which adsorbents should be changed mean that utilizing a large amount of Kc does not necessarily result in a high desulfurization rate. Therefore, we investigated the optimal performance of IIG-SOFC utilizing Kc using exergy analysis and LCA. As a result, the maximum exergy efficiency was 28.2%. Likewise, the smallest GWP and ADP was achieved at a desulfurization rate of 100%, Kc usage ratio of 4.5%, and adsorption temperature of 120 °C.

Major Building Materials in Terms of Environmental Impact Evaluation of School Buildings in South Korea

This study aimed to analyze the major building materials in terms of environmental impact evaluation of school buildings in South Korea. Three existing school buildings were selected as the analysis targets, and building materials were analyzed in terms of cumulative weight and six environmental impact categories (global warming potential, abiotic depletion potential, acidification potential, eutrophication potential, ozone-layer depletion potential, and photochemical oxidation potential). The materials were analyzed from an environmental perspective after integrating the six environmental impact categories into the environmental costs. From the analysis, nine major building materials, including ready-mixed concrete, concrete bricks, aggregate, rebar, cement, stone, glass, insulating materials, and wood, were selected for the school buildings. These analysis results can be used as a streamlined evaluation of the environmental impacts of school buildings. It is thought that the simplified life cycle assessment will help make decisions considering environmental characteristics in the early stage of the construction project. Additionally, it will be possible to make LCA efficient in terms of time and cost, one of the largest constraints of the existing building LCA, and effective reduction in the environmental load.

Life cycle assessment of biocemented sands using enzyme induced carbonate precipitation (EICP) for soil stabilization applications

Integrating sustainability goals into the selection of suitable soil stabilization techniques is a global trend. Several bio-inspired and bio-mediated soil stabilization techniques have been recently investigated as sustainable alternatives for traditional techniques known for their high carbon footprint. Enzyme Induced Carbonate Precipitation (EICP) is an emerging bio-inspired soil stabilization technology that is based on the hydrolysis of urea to precipitate carbonates that cement sand particles. A life cycle assessment (LCA) study was conducted to compare the use of traditional soil stabilization using Portland cement (PC) with bio-cementation via EICP over a range of environmental impacts. The LCA results revealed that EICP soil treatment has nearly 90% less abiotic depletion potential and 3% less global warming potential compared to PC in soil stabilization. In contrast, EICP in soil stabilization has higher acidification and eutrophication potentials compared to PC due to byproducts during the hydrolysis process. The sensitivity analysis of EICP emissions showed that reducing and controlling the EICP process emissions and using waste non-fate milk has resulted in significantly fewer impacts compared to the EICP baseline scenario. Moreover, a comparative analysis was conducted between EICP, PC, and Microbial Induced Carbonate Precipitation (MICP) to study the effect of treated soil compressive strength on the LCA findings. The analysis suggested that EICP is potentially a better environmental option, in terms of its carbon footprint, at lower compressive strength of the treated soils.

Implementing Artificial Intelligence Techniques to Predict Environmental Impacts: Case of Construction Products

Nowadays, product designers, manufacturers, and consumers consider the environmental impacts of products, processes, and services in their decision-making process. Life Cycle Assessment (LCA) is a tool that assesses the environmental impacts over a product’s life cycle. Conducting a life cycle assessment (LCA) requires meticulous data sourcing and collection and is often time-consuming for both practitioner and verifier. However, predicting the environmental impacts of products and services can help stakeholders and decision-makers identify the hotspots. Our work proposes using Artificial Intelligence (AI) techniques to predict the environmental performance of a product or service to assist LCA practitioners and verifiers. This approach uses data from environmental product declarations of construction products. The data is processed utilizing natural language processing (NLP) which is then trained to random forest algorithm, an ensemble tree-based machine learning method. Finally, we trained the model with information on the product and their environmental impacts using seven impact category values and verified the results using a testing dataset (20% of EPD data). Our results demonstrate that the model was able to predict the values of impact categories: global warming potential, abiotic depletion potential for fossil resources, acidification potential, and photochemical ozone creation potential with an accuracy (measured using R2 metrics, a measure to score the correlation of predicted values to real value) of 81%, 77%, 68%, and 70%, respectively. Our method demonstrates the capability to predict environmental performance with a defined variability by learning from the results of the previous LCA studies. The model’s performance also depends on the amount of data available for training. However, this approach does not replace a detailed LCA but is rather a quick prediction and assistance to LCA practitioners and verifiers in realizing an LCA.

Diagnosing the environmental impacts of typical fatliquors in leather manufacture from life cycle assessment perspective

The environmental impacts of typical fatliquors were diagnosed by the life cycle assessment of industrial production and use (post-tanning) processes. Life cycle impact assessment and sensitivity analysis showed that fatliquor and fatliquoring operation were the major contributors to the environmental impacts of post-tanning because a large amount of fatliquors was consumed during fatliquoring operation. The environmental impacts of fatliquors decreased in the following order: chlorinated paraffin (CP) > sulfonated rape oil (SNR) > sulfated rape oil (SR) > phosphated rape oil (PR) > oxidized–sulfited rape oil (OSR). Sulfuric acid, fuming sulfuric acid, and chlorine used for fatliquor modification gave the main contribution to most impact categories for SR, SNR, and CP production, whereas rape oil contributed the most for PR and OSR production. OSR use process reduced the primary energy demand, abiotic depletion potential, and global warming potential by 38.5%, 56.0%, and 48.5%, respectively, compared with CP use process. These results suggested that biomass-derived fatliquors, especially oxidized–sulfited and phosphate modified fatiliquors, helped reduce the environmental burdens in leather manufacturing.Graphical

Life Cycle Assessment of Existing and Alternative Options for Municipal Solid Waste Management in Saint Petersburg and the Leningrad Region, Russia

A waste reform was recently introduced in Russia to divert waste from landfills. To help advance the reform, this paper presents a life cycle assessment of the municipal solid waste management system in Russia’s second largest city—Saint Petersburg—and its neighboring Leningrad region. Five scenarios were evaluated: the current state of the system (S0), its expected post-reform state in 2024 (S1), and its state improved by increased landfill gas collection (S2), by increased waste incineration (S3), and by separate collection of waste (S4). The environmental impact was assessed in terms of climate change, acidification, eutrophication, and abiotic resource depletion (fossil fuels). The results showed an overall reduction in the environmental impact of the waste management system across all impact categories and all scenarios studied. The largest reduction in all impact categories (except abiotic resource depletion) was achieved through source separation of municipal solid waste. Particularly, global warming potential was reduced from 0.328 kg CO2-eq./kg waste generated in S0 to 0.010 kg CO2-eq./kg waste in S4. Regarding abiotic resource depletion potential (fossil fuels), the incineration scenario is the most beneficial, since it reduces the impact by 573%.

Potential trade-off between water consumption and water quality: life cycle assessment of nonaqueous solvent dyeing

Fashion industry consumes over 60% of global fibers and attracts increasing attentions due to its environmentally polluting supply chain. In addition to natural fibers cultivation, wet processes of textile manufacturing are also important contributors to water-related impacts due to their large freshwater consumption and the production of chemicals containing wastewater. Despite of efforts made in improving efficiency of water use and wastewater treatment in textile industry, innovative ‘water-free’ technologies, such as nonaqueous dyeing technology using organic solvent, have been developed and demonstrated to reduce water consumption significantly. However, the potential impact on water quality by organic solvents induced in supply chain of this emerging technology remains unassessed, posing an unknown risk of its promotion. Hence, in the present study, a comprehensive life cycle assessment is applied to evaluate its full environmental impacts, including those on ecosystem and human health caused by decamethylcyclopentasiloxane (D5) as the solvent used. Further, the nonaqueous dyeing system is compared with traditional aqueous dyeing technology from both environmental and economic perspectives. Results indicate that nonaqueous dyeing system is advanced in most of environment categories except for abiotic depletion potential (ADP) and Ecotoxicity. However, scenarios analysis reveal that these findings are influenced by the loss fraction of D5 during the solvent recovery process. It is suggested that the loss fraction should be controlled below 2% o.w.f. for the nonaqueous dyeing technology to be advanced throughout all environmental categories. Nonaqueous D5 dyeing could reduce water consumption by 61.30%-79.95% and greenhouse gas emissions by 43.70% compared to the traditional system, delivering a promising contribution to China's 2060 carbon neutrality ambition. Sensitivity and uncertainty analyses are also conducted to investigate the effects of the key parameters (incl. inventory data and USEtox model inputs) and demonstrate the robustness of our assessment.

Process design and optimization of the efficient production of butyl acrylate by reactive azeotropic distillation/pervaporation using different feed ratios

Present industrial development has a great demand for butyl acrylate, an important basic chemical. Efficient synthesis and separation processes are very important for the clean manufacturing of butyl acrylate. In this work, two processes for the preparation of butyl acrylate by reactive distillation coupled with azeotropic distillation (RD-AD) or pervaporation (RD-PV) were proposed. By changing the ratio of reactants, the economic performance of the two processes under different specifications of butyl acrylate was analyzed, and the environmental impact of the two processes in the production process were analyzed. First, the process design using different purity specifications was completed focusing on the reaction kinetics. Then, based on the sequential iterative algorithm, process optimization was carried out with the minimum total annual cost (TAC) as the objective function, and the process with optimal operating conditions was obtained. Finally, TAC and the global warming potential (GWP), acidification potential (AP), abiotic depletion potential (ADP) and human toxic potential (HTP) were used to assess the economic and environmental performance of the proposed processes. The results showed that the RD-AD process had better economic performance, whereas the RD-PV process had better environmental performance. According to the results, the parameters that influenced the TAC for products with different purities were obtained. The TAC of the RD-AD process was 41.39% lower than that of the RD-PV process, and GWP, AP, and ADP of the RD-PV process were respectively 12.67%, 13.68%, and 13.07% lower than those of the RD-AD process.

Life cycle assessment and cost analysis for copper hydrometallurgy industry in China

Understanding the environmental and economic impacts of copper hydrometallurgy throughout the whole life cycle is necessary for sustainable development of the copper industry. In this study, the environmental impacts and economic costs throughout the two major copper hydrometallurgical routes in China, including heap leaching and heap-agitation leaching, are analyzed and compared using the life cycle assessment (LCA) and life cycle cost (LCC) technique. The life cycle inventory compiled from the annual statistics of the Muliashi Copper Mine, and the data regarding energy and materials process are based on the GaBi databases. The environmental impacts are quantified into 12 indicators. The results show that compared with heap leaching route, heap-agitation leaching route reduces 36.8% of abiotic depletion potential (ADP elements), but increases over half of cumulative energy demand (CED), marine aquatic ecotoxicity potential (MAETP) and human toxicity potential (HTP). Furthermore, the stage of electrowinning and agitation leaching contributes the largest environmental impact to heap leaching and heap-agitation leaching route, respectively. This is mainly due to huge consumption of electricity and sulfuric acid. The analysis of economic cost reveals that heap leaching route needs internal cost of $3225/t Cu and external cost of $426/t Cu. Compared with heap leaching route, heap-agitation leaching route increased the internal and external cost by 18.9% and 54.2%, respectively. But the economic return from heap-agitation leaching is double that from heap leaching. Together, these results indicate heap-agitation leaching has a larger environmental impact and higher economic benefit than heap leaching, which is helpful for the government to design ecological compensation policies in the balance between ecological environment and economic development.

Comparative life cycle assessment of LFP and NCM batteries including the secondary use and different recycling technologies

Lithium iron phosphate (LFP) batteries and lithium nickel cobalt manganese oxide (NCM) batteries are the most widely used power lithium-ion batteries (LIBs) in electric vehicles (EVs) currently. The future trend is to reuse LIBs retired from EVs for other applications, such as energy storage systems (ESS). However, the environmental performance of LIBs during the entire life cycle, from the cradle to the grave, has not been extensively discussed. In this study, life cycle assessment (LCA) was used to quantify and compare the environmental impacts of LFP and NCM batteries. Apart from the phases of production, the first use in EVs, and recycling, the repurposing of retired LIBs and their secondary use in the ESS were also included in the system boundary. Also, the environmental impacts of various recycling processes were evaluated. The LCA results suggested that the NCM battery had better comprehensive environmental performance than the LFP one but shorter service life over the whole life cycle. In China, the first and secondary use phases contributed most to the environmental impacts with electricity mostly generated from fossil fuels. The LIB production phase was relevant to all assessed impact categories and contributed more than 50% to Abiotic Depletion Potential (ADP elements) particularly. The environmental loads could be mitigated through the recovery of metals and other materials. And, hydrometallurgy was recommended for recycling waste LIBs by better environmental advantages than pyrometallurgy and direct physical recycling. Sensitivity analysis revealed that by optimizing the charge-discharge efficiency of LIBs, particularly LFP batteries, all environmental burdens could be considerably decreased. Therefore, improving the electrochemical performance of LIBs and increasing the use proportion of clean energy were crucial to reduce the environmental impacts over their entire life cycle.

Comparative Life-Cycle Assessment of Liquefied Natural Gas and Diesel Tractor-Trailer in China

Many countries, especially China, have extensively promoted liquefied natural gas (LNG) to replace diesel in heavy-duty vehicles for to achieve sustainable transport aims, including carbon peaks and neutrality. We developed a life-cycle calculation model for environmental load differences covering vehicle and fuel cycles to comprehensively compare the LNG tractor-trailer and its diesel counterpart in China on a full suite of environmental impacts. We found that the LNG tractor-trailer consumes less aluminum but more iron and energy; emits less nitrogen oxide, sulfur oxide, nonmethane volatile organic compounds, and particulate matter but more greenhouse gases (GHG) and carbon monoxide (CO); and causes less abiotic depletion potential, acidification potential, and human toxicity potential impacts but more global warming potential (GWP) and photooxidant creation potential (POCP) impacts. Poor fuel economy was found to largely drive the higher life-cycle GHG and CO emissions and GWP and POCP impacts of the LNG tractor-trailer. Switching to the LNG tractor-trailer could reduce carbon dioxide by 52.73%, GWP impact by 44.60% and POCP impact by 49.23% if it attains parity fuel economy with its diesel counterpart. Policymakers should modify the regulations on fuel tax and vehicle access, which discourage improvement in LNG engine efficiency and adopt incentive polices to develop the technologies.

Energy analysis and life cycle assessment of a thermal energy storage unit involving conventional or recycled storage materials and devoted to industrial waste heat valorisation

Any system intending to improve the environmental performances of a process should be assessed by a Life Cycle Assessment. This work draws up the environmental profile of the heat provided by a storage system recovering industrial waste heat at high temperature (500 °C) through 5 selected indicators: Cumulative Energy Demand, Global Warming Potential, abiotic depletion potential, particle matter and freshwater eutrophication. The calculated indicators were compared to those of the fossil fuel substituted by the recovered heat, that is to say natural gas, and proved to be reduced. Then, the environmental payback times were calculated; and an energetic profitability evaluation by the Energy Returned on Investment expanded on the profile. Besides, the influence of operating conditions variations was investigated through a parametric study. An optimal number of cycles to provide the same amount of energy may be defined, as a compromise between the abiotic resource depletion potential reduction with smaller tanks performing more cycles and the energy returned on investment deteriorated with the operational energy consumption increased due to higher pressure drop with smaller tank diameter. The most rewarding environmental performances concerned the Cumulative Energy Demand, Global Warming Potential indicators of the provided heat, about 1.2 kgCO2-eq and 65 MJ-eq per kWh (payback time lower than 3 months), and the Energy Returned on Investment that doubled compared to natural gas, e.g. reached a value of 55. The positive effect of using recycled storage materials on the resource depletion indicator were enlightened, notably when the operating conditions strayed from the reference case.

Techno-economic evaluation and life cycle assessment of a biorefinery using winery waste streams for the production of succinic acid and value-added co-products

This study presents techno-economic evaluation and life cycle assessment of a novel biorefinery using the three main waste streams generated by wineries for the production of bio-based succinic acid (SA), crude phenolic-rich extract, grape-seed oil, calcium tartrate and crude tannin-rich extract. Process design has been employed for the estimation of material and energy balances and the sizing of unit operations. The Minimum Selling Price of succinic acid production within a winery waste biorefinery ranges from $1.23–2.76/kgSA depending on the market price and the potential end-uses of the extracted fractions. The Global Warming Potential and the Abiotic Depletion Potential of winery waste valorisation through the proposed biorefinery are 1.47 kg CO2-eq per kg dry waste and 25.2 MJ per kg dry waste, respectively. Biorefining of winery waste could lead to the development of a sustainable and novel bioeconomy business model with new market opportunities and efficient waste management.

Environmental Impacts and Benefits of the End-of-Life of Building Materials: Database to Support Decision Making and Contribute to Circularity

This paper outlines a methodology for structuring a generic database of environmental impacts on the end-of-life phase of buildings, which can be used at the national level, in accordance with European standards. A number of different options are also considered for managing construction and demolition waste (CDW), as well as for promoting the circularity of materials in construction. The database structure has been developed for use by the main stakeholders who decide the disposal scenario for the main CDW flows, assess waste management plans, and identify the corresponding environmental aspects. The impact categories considered in this paper are global warming potential (GWP) and the abiotic depletion potential of fossil fuels (ADP (f.f.)). This lifecycle assessment (LCA) database further facilitates the identification of important information, such as possible treatments for CDW, or suppliers of recycled materials for use in new construction. Two demolition case studies were used to confirm the benefits of the proposed database. Two demolition scenarios are assessed—traditional and selective—in order to demonstrate the advantage of selective demolition in waste management. The results obtained from the environmental assessment of CDW flows demonstrate that the proposed database can be an important and useful tool for decision making about the end-of-life of construction materials, as it is designed to maximize their reuse and recycling. An innovative online platform can be created based on this database, contributing to the reduction of the environmental impacts associated with the end-of-life phase of buildings.

Sustainable utilization of waste carbon black in alkali-activated mortar production

This article investigates the potential utilization of waste carbon black (WCB) resulting from the aluminum industry as a by-product material in the fly ash-based geopolymer composites production. Experimental study was conducted to evaluate the effect of WCB on the performance of the geopolymer. Different contents of WCB including 5%, 10%, 15%, 20%, 30%, and 40%,by weight of the fly ash, have been incorporated in the geopolymer mix as either additives or fly ash replacement. Life cycle assessment (LCA) has also been conducted to evaluate the landfills utilization and the environmental impact of the WCB incorporation. The experimental results reflected that the WCB could be used as additives in small quantities (5% of fly ash weight) to the geopolymer mix without negatively affecting its performance. Adding 5% of WCB insignificantly enhanced the compressive strength of the geopolymer by 5%, increased its workability and density by 3% and 4%, respectively, and did not affect its excellent thermal stability. Scanning electron microscopic (SEM) imaging showed more unreacted fly ash particles combined with more voids and cracks within the microstructure of the geopolymer with high WCB content. Finally, incorporating WCB in the geopolymer production improved the utilization of landfills use and reduced the global warming potential, acidification potential, eutrophication potential and abiotic depletion potential.