Based on a road reconstruction case study, the advantages and disadvantages of two alternative road pavement rehabilitation techniques, a hypothetically defined comparable traditional approach and an ...actually used cold-in-place-recycling approach, both of which enable a comparable extension of road service life of about 20 years, were investigated by means of Life Cycle Assessment. The results showed that the considered environmental impacts of the traditional approach exceeded those of the cold-in-place-recycling approach: by only 1% with regard to Global Warming, by 18% with regard to Acidification, by 15% with regard to the Abiotic Depletion of Fossil Fuels, and by 16% with regard to primary energy consumption. In the case of the traditional approach, the use of larger amounts of natural aggregate and the transportation of materials significantly contributed to emissions and the consumption of fossil fuels and energy, whereas the cold-in-place-recycling approach was sensitive to the use of cement, whose production results in relatively high emissions, especially of greenhouse gasses. In the case of the traditional approach, sensitivity analyses were carried out with regard to the use of aggregate from a quarry instead of a gravel pit, and to the delivery distance of material hauled away from the distressed road during rehabilitation works (extending the one-way delivery distances from 20 to 100 km). It was found that, if aggregate from a quarry is used instead of from a gravel pit, then the various environmental impacts of the traditional approach would exceed those of the cold-in-place-recycling approach by factors which range between 1.3 and 1.7. Increasing the transportation distance of hauled-away materials from 20 km to 100 km, the impacts of the traditional approach would exceed the impacts of the cold-in-place-recycling approach by a factor of 1.4 (Global Warming) and 1.6 (Acidification and Abiotic Depletion of Fossil Fuels). A further sensitivity analysis was carried out in the case of the cold-in-place-recycling approach, with regard to the use of Portland cements containing different amounts of clinker. It was found that the use of cements with a higher clinker content results in an increase in the Global Warming impact to a level significantly higher than that of the traditional approach.
•Environmental benefit of recycling versus conventional scenario was confirmed.•However, carbon footprints of two compared scenarios are similar.•Recycling scenario is very sensitive to the type of Portland cement.
Secondary raw materials (SRMs) tend to be a valuable replacement for finite virgin materials especially since construction works (i.e., building and civil engineering work such as road construction) ...require vast quantities of raw materials. Using SRM originating from recycling a broad range of inorganic waste materials (e.g., mining waste, different industrial wastes, construction, and demolition waste) has been recognized as a promising, generally more cost-efficient, and environmentally friendly alternative to the exploitation of natural resources. Despite the benefits of using SRM, several challenges need to be addressed before using SRM even more. One of them is the long-term durability and little-known response of construction works built using such alternative materials. In this paper, we present the activities to establish a fully functioning digital twin (DT) of a road constructed using SRM. The first part of the paper is devoted to the theoretical justification of efforts and ways of establishing the monitoring systems, followed by a DT case study where an integrated data environment synthesizing a Building Information Model and monitored data is presented. Although the paper builds upon a small scale, the case study is methodologically designed to allow parallels to be drawn with much larger construction projects.
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•Different types of nZVI were used for the remediation of effluent water from SBWTP.•Remediation depends on the reactivity of nZVI, iron load, mixing and settling times.•In-house nZVI ...effectively disinfected effluent water, but contaminated it with B.•Ammonium N was formed from organic N and by the reduction of nitrates and nitrites.•Nanofer25 slurry the most effective removal of elements and inactivated pathogens.
Nanoremediation procedures are usually designed so that only one contaminant or similar class of contaminants is being considered. In the present work, a holistic approach was applied towards processes which simultaneously occur after the treatment of real effluent water from a small biological wastewater treatment plant (SBWTP) with different nanoscale zero-valent iron (nZVI) particles. Three different types of nZVI particles were tested: in-house nZVI, commercially available Nanofer STAR and Nanofer25 slurry, which differ in reactivity and their methods of synthesis. In order to optimise the conditions for the efficient removal of selected elements, nitrogen species, and pathogenic bacteria (Coliform bacteria, Escherichia coli, Intestinal Enterococci and Clostridium perfringens), effluent water samples were treated with different iron loads from each of the investigated nZVI at various mixing and settling times.
The results demonstrated that in-house nZVI, which is the most reactive of the nanoparticles tested, most effectively removed metals and inactivated pathogenic bacteria. However, the application of in-house nZVI is restricted, as it contaminates the remediated water with B, which originated from the reagents used in its synthesis. To a certain extent, all of the investigated types of nZVI reduced nitrates and nitrites to ammonium cations. The additional formation of ammonium nitrogen was the result of the interactions of the nZVI with the organic nitrogen present in the effluent water. At an optimised iron load, mixing time, and settling time, the most efficient removal of elements and disinfection of pathogens was achieved when Nanofer25 slurry was applied.
Fine particulate matter (PM2.5), a detrimental urban air pollutant primarily emitted by traffic and biomass burning, poses disproportionately significant health risks at relatively limited exposure ...during commuting. Previous studies have mainly focused on fixed locations when assessing PM2.5 exposure, while neglecting pedestrians and cyclists, who often experience higher pollution levels. In response, this research aimed to independently validate the effectiveness of bicycle-mounted low-cost sensors (LCS) adopted by citizens, evaluate temporal and spatial PM2.5 exposure, and assess associated health risks in Ljubljana, Slovenia. The LCS quality assurance results, verified by co-location field tests by air quality monitoring stations (AQMS), showed comparable outcomes with an average percentage difference of 21.29 %, attributed to humidity-induced nucleation effects. The colder months exhibited the highest air pollution levels (μ = 32.31 μg/m3) due to frequent thermal inversions and weak wind circulation, hindering vertical air mixing and the adequate dispersion of pollutants. Additionally, PM2.5 levels in all sampling periods were lowest in the afternoon (μ = 12.09 μg/m3) and highest during the night (μ = 61.00 μg/m3) when the planetary boundary layer thins, leading to the trapping of pollutants near the surface, thus significantly affecting diurnal and seasonal patterns. Analysis of exposure factors revealed that cyclists were approximately three times more exposed than pedestrians. However, the toxicological risk assessment indicated a minimal potential risk of PM2.5 exposure. The collaborative integration of data from official AQMS and LCS can enhance evidence-based policy-making processes and facilitates the realignment of effective regulatory frameworks to reduce urban air pollution.
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•PM2.5 poses significant health risks at limited exposure during commuting.•Air quality monitoring stations and citizens' initiatives data integration enhances air pollution assessment.•Air quality monitoring stations co-location validation of low-cost sensors results yielded comparable outcomes.•PM2.5 increased in cold months due to thermal inversions hindering pollutant dispersion.•Cyclist had three times higher PM2.5 exposure than pedestrians.
Temperature control is the primary concern during the design and construction process of mass concrete structures. As the concrete production has an enormous negative environmental impact, the ...development of green mass concretes will eventually become as important as the thermal characteristics. Therefore, this paper investigates the use of Electric Arc Furnace (EAF) steel slag aggregate for the partial replacement of the natural aggregate in the production of mass concrete. The impact of EAF steel aggregate on mass concrete workability, strength, and thermal behaviour was analysed. In addition, a cradle-to-gate LCA study was conducted to evaluate the environmental footprint and sustainability potential of the tested mass concrete mixtures. The study results suggest that the use of EAF steel slag aggregate in combination with a low-heat cement with a high content of blast furnace slag can significantly lower the temperature, reduce the environmental impact, and increase the sustainability potential of mass concrete, while at the same time providing sufficient workability and compressive strength. The study results indicate that EAF steel slag can be upcycled into an aggregate for the production of green mass concrete mixtures.
Anion-exchange high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used for simultaneous speciation of chromate, molybdate and arsenate. The ...repeatability of measurement tested for multielemental standard solution of chromate, molybdate and arsenate (50 ng mL
of Cr, Mo and As, pH 12) was ± 0.9%, ± 4.9% and ± 4.1%, respectively. Limits of quantification (LOQs) were low (0.53 ng mL
for chromate and arsenate and 1.03 ng mL
for molybdate, expressed as elemental concentrations). A wide linear concentration range (from LOQs to 500 ng mL
) was obtained. The performances of this method enabled simultaneous speciation analysis in samples of water from lysimeters, in which three geotechnical composites, made of recycled waste, were installed in parallel in compacted and uncompacted, 20 times less dense form. The release of toxic chemical species of elements into lysimetric waters from each composite was studied. The results revealed that the degree of compaction and the composition of composites both have a significant influence on leaching of chromate, molybdate and arsenate. The study proved that multielemental speciation analysis is fast and cost-effective method for investigations of environmental impacts of materials, made from recycled waste, and can be used in other similar applications.
Three innovative conservation materials were investigated by means of life cycle assessment (a calcium acetoacetate consolidant for carbonate surfaces, a TEOS-based consolidant for silicate ...substrates, and a photocatalytic suspension). So far not much attention has been paid to materials for the conservation of the built cultural heritage, with regard to their environmental performance. The main aim of this study was to assess the environmental footprint of the above-mentioned conservation materials which arises throughout their life cycle. In this way comparative data are made available for other future LCA studies on consolidants and photocatalytic suspensions. The most heavily polluting processes (i.e. “hotspots”) in the life cycle of the investigated conservation materials were identified, and, where possible, solutions for the further optimization of their environmental performance were proposed. In the case of life cycle of the two above-mentioned consolidants, the majority of emissions can be attributed to the synthesis of the constituent materials which are used to make the final products. Ethyl polysilicate is the largest contributor to the environmental footprint of the TEOS-based consolidant. On the other hand, in the life cycle of the calcium acetoacetate consolidant most of the environmental burdens are contributed by the synthesis of acetone-dicarboxylic acid. Around 0.47 kg of CO2 equivalent emissions affecting global warming are released to the air during the life cycle of 1 L of calcium acetoacetate (considering solely the upstream and core processes), whereas this value is higher in the case of the life cycle of the TEOS-based consolidant, i.e. 3.77 kg of CO2 equivalent emissions. In the case of the life cycle of the investigated photocatalytic suspension, although 1 L of this suspension is responsible for the release of only 0.1 kg of CO2 equivalent emissions over its life cycle (excluding the case-specific downstream processes) the heaviest environmental impact is caused by the production of packaging material (e.g. plastic buckets and other types of plastic containers). Taking into account the above-mentioned facts, there are not many possibilities for the reduction of the environmental burdens of the two investigated consolidants by the environmental optimization of the processes involved in the core and downstream stages of their life cycles. In the life cycle of the photocatalytic suspension, the environmental burdens related to greenhouse gas emissions could be reduced by more than 10% if a cleaner form of electricity production were to be adopted. A further aim of this paper is to promote sustainability in the field of management of the immovable cultural heritage. Although the described conservation materials have only a minor environmental effect in the field of the management of the immovable cultural heritage, the significance of sustainability is presented to conservators on a practical example.
•In life cycle of the consolidants, hotspot refers to synthesis of constituents.•1 L of a TEOS-based consolidant is responsible for release of 3.8 kg of CO2 equiv.•1 L of a calcium acetoacetate is responsible for release of 0.5 kg of CO2 equiv.•In life cycle of a photocatalytic suspension, hotspot refers to a bucket production.•1 L of a photocatalytic suspension is responsible for release of 0.12 kg of CO2 equiv.
Significant criteria for choosing materials (consolidants and protective coatings) for the conservation of the built cultural heritage were gathered from the literature and by consultation with ...experts working on the preservation of cultural heritage. Ten criteria were chosen from these, and a questionnaire was prepared and sent to stakeholders in the cultural heritage conservation domain in order to evaluate, score and rank the importance of the proposed criteria. Based on the results obtained a decision support tool was developed, aimed at conservators and other stakeholders, to help them to make sustainable decisions with regard to the selection of conservation materials for treatment of the built cultural heritage. Performance characteristics and health and safety were identified to be the most important criteria. A preliminary decision can be made based on these two criteria, however, reversibility, minimum intervention and re-treatability are also of very high importance and additional information about these characteristics of the material are required to support decisions. Information about environmental performance, peer recommendation, the application techniques, the price and availability of the materials, which are also integrated in decision support tools, can help conservators and stakeholders to reach a final decision on interventions. The study also provides feedback for the manufacturers of conservation materials. For the users of material, it is very important that the manufacturers clearly identify key characteristics (i.e. criteria) on the product, including those related with environmental performance of the materials.
Light eutrophication in show caves and other light-deprived humid environments can support visible growth of microbial mats, with photoautotrophs as the dominant group of organisms. Photosynthetic ...pigments of aerophytic cyanobacteria and eukaroytic algae impose a greenish patina upon surfaces to which -- with other community members -- they adhere strongly. Diverse eukaryotic algae, fungi, flagellates and amoebozoans were also identified within the community. These "human induced diversity hotspots" in caves are responsible for the biodeterioration of colonized surfaces that is a common result of the synergistic effects of phototrophs and heterotrophs. When sites become colonized by higher plants, such as mosses, liverworts and ferns in species succession, irreversible biodeterioration impact on rocks and speleothems becomes an even more urgent issue. Historical inscriptions and rock-art paintings are particularly sensitive to biodeterioration. Lampenflora also affects components of the cave fauna, which not only graze upon it, but also facilitate its dispersal to other parts of the caves. It can be considered a direct indicator for light eutrophication and of the available energy within the cave ecosystem.
Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of ...immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites.
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