Comparative Life Cycle Assessment of possible methods for the treatment of contaminated soil at an environmentally degraded site

Environmental impact assessment of the electrokinetic adsorption barriers to remove different herbicides from agricultural soils

In this study, the sustainability of the electrokinetic remediation soil flushing (EKSFs) process integrated without and with adsorption barriers (EKABs) have been evaluated for the treatment of four soils contaminated with Atrazine, Oxyfluorfen, Chlorosulfuron and 2,4-D. To this purpose, the environmental effects of both procedures (EKSFs and EKABs) have been determined through a life cycle assessment (LCA). SimaPro 9.3.0.3 was used as software tool and Ecoinvent 3.3 as data base to carry out the inventory of the equipment of each remediation setup based on experimental measurements. The environmental burden was quantified using the AWARE, USEtox, IPPC, and ReCiPe methods into 3 Endpoint impact categories (and damage to human health, ecosystem and resources) and 7 Midpoints impact categories (water footprint, global warming potential, ozone depletion, human toxicity (cancer and human non-cancer), freshwater ecotoxicity and terrestrial ecotoxicity). In general terms, the energy applied to treatment (using the Spanish energy mix) was the parameter with the greatest influence on the carbon footprint, ozone layer depletion and water footprint accounting for around 70 % of the overall impact contribution. On the other hand, from the point of view of human toxicity and freshwater ecotoxicity of soil treatments with 32 mg kg-1 of the different pesticides, the EKSF treatment is recommended for soils with Chlorosulfuron. In this case, the carbon footprint and water footprint reached values around 0.36 kg of CO2 and 114 L of water per kg of dry soil, respectively. Finally, a sensitivity analysis was performed assuming different scenarios.

Validation of the recycled backfill material for the landslide stabilization at a railway line

In mountain areas landslides many times endanger safety of transport infrastructures, and these must be stabilized with retaining wall structures. In this paper the validation of a new composite as a backfill material for landslide stabilization with a large scale demo retaining wall is presented. The new composite was made from residues of paper industry, which uses for its production deinking process. New composite was validated with the laboratory tests, construction of small demo sites and at the end with a large demo retaining wall structure with a length of 50 m. It was concluded that the paper sludge ash and the paper sludge are in proportion 70:30, compacted on the optimal water content and maximum dry density, reached sufficient uniaxial compressive and shear strength. However, the composite's hydration processes required the definition of an optimal time between the composite mixing and installation. In 2019, the retaining wall structure from the new composite was successfully built. The large demo structure is an example of the knowledge transfer from the laboratory to the construction site, in which composite and installing technology could be verified.

Recent developments and prospects of sustainable remediation treatments for major contaminants in soil: A review

Rapid industrialisation and urbanisation are contributing to the entry of emerging contaminants into the environment, posing a significant threat to soil health and quality. Therefore, several remediation technologies have been investigated and tested at a field scale to address the issue. However, these remediation technologies face challenges related to cost-effectiveness, environmental concerns, secondary pollution due to the generation of by-products, long-term pollution leaching risks, and social acceptance. Overcoming these constraints necessitates the implementation of sustainable remediation methodologies that prioritise approaches with minimal environmental ramifications and the most substantial net social and economic advantages. Hence, this review delves into diverse contaminants that threaten soil health and quality. Moreover, it outlines the research imperatives for advancing innovative remediation techniques and effective management strategies to tackle this concern. The review discusses a remediation treatment train approach that encourages resource recovery, strengthens the circular economy, and employs a Life Cycle Assessment (LCA) framework to assess the environmental impacts of different remediation strategies. Additionally, the study explores mechanisms to integrate sustainability principles into soil remediation practices. It underscores the necessity for a comprehensive and systematic approach that takes into account the economic, social, and environmental consequences of remediation methodologies in the development of sustainable solutions.

Real-time emission characteristics, health risks, and olfactory effects of VOCs released from soil disturbance during the remediation of an abandoned chemical pesticide industrial site

Volatile organic compounds (VOCs) released along with soil disturbance during the remediation of abandoned industrial sites have attracted great attention due to their possible toxicity and odour. However, the real-time emission characteristics of these VOCs and their subsequent effects on health and olfaction are less understood. In this study, the gaseous VOCs released from soil disturbance by excavators and drilling rigs at an abandoned chemical pesticide plant were monitored online with a laboratory-built single photoionization time-of-flight mass spectrometer (SPI-TOFMS). Twelve main VOCs with total mean concentrations ranging from 2350 to 3410 μg m-3 were observed, with dichloromethane (DCM) having a significant contribution. The total concentrations of the remaining 11 VOCs increased substantially during soil disturbance, with the total mean concentrations increasing from 18.65-39.05 to 37.95-297.94 μg m-3 and those of peak concentrations increasing from 28.46-58.97 to 88.38-839.13 μg m-3. This increase in VOC concentrations during soil disturbance leads to an enhanced heath risk for on-site workers. The distinctive difference between the mean and peak concentrations of VOCs indicates the importance of using mean and peak concentrations, respectively, for risk and olfactory evaluation due to the rapid response of the human nose to odours. As a result, the cumulative noncarcinogenic risk at the relatively high pollutant plot was higher than the occupational safety limit, while the total carcinogenic risks at all monitored scenarios exceeded the acceptable limit. Among the VOCs investigated, DCM and trichloroethylene (TCE) were determined to be crucial pollutants for both noncarcinogenic and carcinogenic risks of VOCs. With regard to olfactory effects, organic sulphides, including dimethyl disulphide (DMDS), dimethyl sulphide (DMS), and dimethyl trisulphide (DMTS) were identified as dominant odour contributors (78.28-92.11%) during soil disturbance.

An analysis of design strategies for circular economy through life cycle assessment

The goal of pursuing the circular economy (CE) is spreading more and more in industry, also driven by the introduction of new regulations, considerably affecting product design. However, a quantitative and rigorous evaluation of the environmental impacts of the results obtained by different design strategies used to implementing CE is missing in the literature. Those available only evaluate certain aspects of the life cycle of few products, belonging to specific application fields, in a qualitative way or they refer only to the global warming potential. This study provides a quantitative assessment of the environmental impacts reductions arising from the application of some common design strategies for implementing different CE options (e.g. reuse, waste to energy, remanufacturing), by using some standard indicators. The results were obtained by manually analysing 156 selected case studies of comparative life cycle assessment (LCA), extracted from 136 scientific articles. In them, the environmental impacts of design solutions for CE are compared with those of other solutions were wastes are not exploited. The obtained results have been used to evaluate the different design strategies for CE and to hierarchize them based on environmental sustainability of the solutions associated with them. In addition, an economic evaluation of the strategies, based on the life cycle costing methodology and exploiting the data available in the same articles, was also provided. Among the main achievements, it was found that the hierarchy of the CE options, pursued by the design strategies, to improve environmental sustainability is different from that provided by other studies. In addition, the environmental benefits associated with the different CE options strictly depend by the applied design strategies and the considered products.

Can the green energies improve the sustainability of electrochemically-assisted soil remediation processes?

The green powering of electrochemically-assisted soil remediation processes had been strongly discouraged. Low remediation efficiencies have been reported as a consequence of the reversibility of the transport processes when no power is applied to the electrodes, due to the intermittent powering of renewable sources. However, it has been missed a deeper evaluation from the environmental point of view. This work goes further and seeks to quantify, using life cycle assessment tools, the environmental impacts related to the electro-kinetic treatments powered by different sources: grid (Spanish energy mix), photovoltaic and wind sources. The global warming potential and the ozone depletion showed higher environmental impacts in case of using green energies, associated with the manufacturing of the energy production devices. In contrast to that, results pointed out the lowest water consumption for the treatment powered with solar panels. The huge water requirements to produce energy, considering a Spanish energy mix, drop the sustainability of this powering strategy in terms of water footprint. Regarding toxicities, the pollutant toxicity was highly got rid of after 15 days of treatment, regardless the powering source used. Nevertheless, the manufacturing of energy and green energy production devices has a huge impact into the toxicity of the remediation treatments, increasing massively the total toxicity of the process, being this effect less prominent by the electro-kinetic treatment solar powered. In view of the overall environmental impact assessed, according to mid and endpoint impact categories, it can be claimed that, despite the high energy requirements and affectation to the global warming potential, the use of solar power is a more sustainable alternative to remediate polluted soils by electrochemical techniques.

Using Recycled Material from the Paper Industry as a Backfill Material for Retaining Walls near Railway Lines

The construction industry uses a large amount of natural virgin material for different geotechnical structures. In Europe alone, 11 million tonnes of solid waste is generated per year as a result of the production of almost 100 million tonnes of paper. The objective of this research is to develop a new geotechnical composite from residues of the deinking paper industry and to present its practical application, e.g., as a backfill material behind a retaining structure. After different mixtures were tested in a laboratory, the technology was validated by building a pilot retaining wall structure in a landslide region near a railway line. It was confirmed that a composite with 30% deinking sludge and 70% deinking sludge ash had a high enough strength but experienced some deformations before failure. Special attention was paid to the impact of transport, which, due to the time lag between the mixing and installation of the composite, significantly reduced its strength. The pilot retaining wall structure promotes the use of recycled materials with a sustainable design, while adhering to government-mandated measures.

Application of life cycle assessment as a tool for evaluating the sustainability of contaminated sites remediation: A systematic and bibliographic analysis

As the discussion surrounding sustainable remediation has advanced, numerous tools have been developed to evaluate the sustainability of remediation technologies, including life cycle assessment (LCA). In the present study, a systematic and bibliometric analysis of scientific articles indexed in the databases of Scopus and the Web of Science in the field of LCA was performed, particularly studies relating to the remediation of contaminated sites from a sustainability perspective. We selected a bibliographic portfolio (BP) of papers related to sustainable remediation using LCA. Then, we performed a bibliometric analysis of the selected BP, presenting theoretical development, highlighting the authors, journals, and countries associated with these publications. Finally, we conducted a thematic synthesis and reviewed the prospects for future research. The BP was composed of 44 papers from 2007 to 2018. In 2018 there was the highest number of publications, corresponding to 27% of the total BP. The results showed that developed countries have generated the largest number of publications, whereas developing countries had lower representation in the BP. However, China stands out as the second country with the highest number of publications. The thematic analysis showed that most articles have aimed to assess the environmental impacts of remediation techniques. However, several publications have performed a broader analysis considering the economic and social pillars of sustainability through using LCA in conjunction with other tools. The study also highlights the main application of LCA in decision-making on the remediation processes in the context of sustainable remediation. The present research study makes several new contributions, providing academics and practitioners with an overview of the implementation of LCA in the field of sustainable remediation of contaminated sites through sorting published data according to scientific indexes and bibliometrics, describing the main research approaches, and highlighting prospects for new research.