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.
The ever-growing worldwide demand for fired clay brick has resulted in the shortage of clay in many parts of the world. Therefore, there is a need to look for more sustainable alternative materials ...for the brick manufacturing. This study has investigated the potential use of the untreated Drava River sediment as a substitute material for clay in the production of fired bricks, with the research being conducted at both laboratory and industrial level. At the laboratory level, brick specimens were prepared by mixing clay with different river sediment proportions (ranging from 10 to 50 wt%) and were fired at 950 °C, with microstructural and various physical–mechanical properties being analyzed. Elevated carbonate content in Drava river sediment results in higher weight loss during firing at temperatures up to 950 °C, comparing to firing pure brick-making clay. Consequently, the addition of sediment increases porosity of fired bricks, which results in lowering of their mechanical properties. Results reveal that the compressive strength of the pure clay sample was 79.5 MPa, while the compressive strength of the sample with the addition of river sediment from 10 wt% to 50 wt% decreased from 73.9 MPa to 26.2 MPa, respectively. Despite the lower compressive strength, the 26.2 MPa is still above the limit value of 10 MPa specified in the standard EN 772–1 1. At the industrial level, hollow clay bricks were prepared with 20 wt% of the river sediment and fired in a tunnel kiln. Inclusion of the river sediment also decreased compressive strength from 38 MPa for pure mixture to 26 MPa for 20 wt% of the sediment addition, confirming usability of Drava sediment in brick production. In addition, LCA study has been conducted to evaluate the environmental impacts associated with the industrial production of classic bricks and bricks with the addition of the river sediment. The obtained results have shown that the bricks made with the addition of the Drava River sediment are sustainable and environmentally friendly and meet all the requirements specified in the relevant regulatory standard.
•Due to their properties river sediments can serve as raw material for clay based sector.•Laboratory investigation confirmed potential replacement of virgin clay with sediment in the amount of up to 30 mass %.•Industrial pilot production with 20 mass % of replacement resulted with clay bricks which meet the requirements of EN 771–1.•LCA analysis has shown the benefits of such replacement.
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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.
Alkali-activated foams (AAFs) are inorganic porous materials that can be obtained at temperatures well below 100°C with the use of inorganic wastes as aluminosilicate precursors. In this case, fly ...ash derived from a Slovenian power plant has been investigated. Despite the environmental benefits
, due to saving of energy and virgin materials, when using waste materials, it is of extreme importance to also evaluate the potential leaching of heavy metal cations from the alkali-activated foams. This article presents an environmental study of a porous geopolymer derived from this particular fly ash, with respect to the leachability of potentially hazardous elements, its environmental toxicity as determined by biological testing, and the environmental impact of its production. In particular, attention was focused to investigate whether or not 1,000°C-fired alkali-activated fly ash and metakaolin-based foams, cured at 70°C, are environmentally friendlier options compared to unfired ones, and attempts to explain the rationale of the results were done. Eventually, the firing process at 1,000°C, apart from improving technical performance, could reinforce heavy metal cation entrapment within the aluminosilicate matrix. Since technical performance was also modified by addition of different types of activators (K-based or Na-based), as well as by partial replacement of fly ash with metakaolin, a life cycle assessment (LCA) analysis was performed to quantify the effect of these additions and processes (curing at 70°C and firing at 1,000°C) in terms of global warming potential. Selected samples were also evaluated in terms of leaching of potentially deleterious elements as well as for the immobilization effect of firing. The leaching test indicated that none of the alkali-activated material is classified as hazardous, not even the as-received fly ash as component of new AAF. All of the alkali-activated foams do meet the requirements for an inertness. The highest impact on bacterial colonies was found in samples that did not undergo firing procedures, i.e., those that were cured at 70°C, which induced the reduction of bacterial
viability. The second family of bacteria tested,
, appeared more resistant to the alkaline environment (pH = 10-12) generated by the unfired AAMs. Cell viability recorded the lowest value for unfired alkali-activated materials produced from fly ash and K-based activators. Its reticulation is only partial, with the leachate solution appearing to be characterized with the most alkaline pH and with the highest ionic conductivity, i.e., highest number of soluble ions. By LCA, it has been shown that 1) changing K-based activators to Na-based activators increases environmental impact of the alkali-activated foams by 1%-4% in terms of most of the impact categories (taking into account the production stage). However, in terms of impact on abiotic depletion of elements and impact on ozone layer depletion, the increase is relatively more significant (11% and 18%, respectively); 2) replacing some parts of fly ash with metakaolin also results in relatively higher environmental footprint (increase of around 1%-4%, while the impact on abiotic depletion of elements increases by 14%); and finally, 3) firing at 1,000°C contributes significantly to the environmental footprint of alkali-activated foams. In such a case, the footprint increases by around one third, compared to the footprint of alkali-activated foams produced at 70°C. A combination of LCA and leaching/toxicity behavior analysis presents relevant combinations, which can provide information about long-term environmental impact of newly developed waste-based materials.
The purpose of this study was to develop a compatible repair mortar for two lithotypes of Peračica tuff (Slovenia): fine-grained and coarse-grained. Mineralogical–petrographic characterization of ...tuff was carried out via optical microscopy and X-ray powder diffraction, and the relevant physical–mechanical properties of tuff and repair mortars were determined: capillary water absorption, water absorption at atmospheric pressure, open porosity, compressive strength and resistance to salt crystallization. A repair mortar was prepared by mixing crushed Peračica tuff and quartz sand, with different grain size and mass ratios, and ethyl silicate (KSE 500 STE, Remmers) as a binder. The results showed that with an appropriate combination of crushed tuff, quartz sand and ethyl silicate, a compatible repair mortars can be obtained for both lithotypes.
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.
Purpose
In this study, the environmental performance of three newly developed materials for the conservation of built Cultural Heritage is preliminary evaluated by means of life cycle assessment ...(LCA). Although LCA has been adopted since many years in many fields, including the construction industry, still it is barely used the field of the Cultural Heritage conservation. Therefore, this paper aims to put a step forward to a wider use of the method for a more sustainable conservation of built heritage.
Methods
Cradle-to-gate approach was applied, which includes activities beginning with production of constituent and ancillary materials and concluding with the manufacturing of the product and its packaging. The functional unit was the production of 1 kg of the consolidant stored in a canister and ready to use. Ecoinvent database was used for the life cycle inventory of chemicals. This database was also taken into account to evaluate impacts related with energy (electricity) needs during manufacturing of the consolidants and production of polyethylene canisters (packaging material). The IMPACT 2002+ method was used to select the impact categories.
Results and discussion
The consolidants under investigation are calcium acetoacetate and two calcium alkoxides (calcium ethoxide and calcium isopropoxide). In the case of calcium acetoacetate consolidant, the highest environmental impact is related to the use of acetone dicarboxylic acid as raw material. Manufacturing process of the final product is not an energy-demanding process; hence, it is regarded as relatively clean from the environmental point of view. In the case of calcium ethoxide and calcium isopropoxide nanosuspensions, the innovative materials just recently developed for conservation purpose, manufacturing has been performed and optimized at a kg/lab scale; therefore, the results must be considered provisional. The two calcium alkoxides nanosuspensions show a relatively high environmental footprint that reflect the high consumption of ancillary materials, i.e. solid CO
2
used to cool down the reaction and liquid ammonia as catalyst, currently released in the atmosphere.
Conclusions
The environmental footprint of calcium acetoacetate is relatively low showing that 1 kg of the consolidant is associated to 0.32 kg of CO
2
equivalent emissions. In the case of two calcium alkoxides nanosuspensions, the global warming impact amounts to 198 kg (calcium ethoxide, 1 kg) and 132 kg (calcium isopropoxide, 1 kg) of CO
2
equivalent emissions. Given the planned optimization of the industrial production currently under investigation, the environmental footprint of the two calcium alkoxides nanosuspensions is expected to reduce between 60 and 85%.
Review of: The EIT Urban Mobility Knowledge and Innovation Community: More pleasant and sustainable living in European cities through innovative mobility solutions. EIT Urban Mobility (2021) EIT ...urban mobility strategic agenda 2021–2027. Barcelona. Reviewed by: Anja Ilenič, Alenka Mauko Pranjić, Darko Kokot, Ana Mladenovič, Mateja Košir.
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