Projects / Programmes
Green and sustainable remediation of contaminated soils for urban land use
| Code |
Science |
Field |
Subfield |
| 4.03.00 |
Biotechnical sciences |
Plant production |
|
| Code |
Science |
Field |
| B410 |
Biomedical sciences |
Soil science, agricultural hydrology |
| Code |
Science |
Field |
| 4.01 |
Agricultural and Veterinary Sciences |
Agriculture, Forestry and Fisheries |
Urban agriculture, contaminated garden soil, remediation, soil revitalization
Researchers (10)
Organisations (2)
Abstract
Soil contamination, caused by the large amounts of man-made pollutants and chemicals that are being anchored into agricultural and urban soils every day, is becoming a major problem. Soils are the basis for more than 90% of worldwide food production. Growing demand for food and accelerating soil degradation driven by climate changes will increase the need to use abandoned contaminated land such are former landmine sites and urban areas for food production. Already urban allotment gardens are being offered by local governments to encourage low income and senior citizens to produce their own food. In the United Kingdom, 87% of households tend a domestic garden. Many cities in Europe formed from an industrial nucleus and have inherited a long industrial history and an associated legacy of urban soil contamination. In particular toxic metals (commonly referred as heavy metals) are the main causes of concern as they are non-degradable and persists in the soil.
All around the world urban agriculture, even on contaminated soil, is booming fulfilling diverse functions including food production, community building and reducing socio-economic tensions. However, crop samples from inner city and other urban vegetable gardens are frequently reported to exceed safety standards for toxic metals concentration in food crops. Exceedingly high levels of Pb were measured in more than half of crop samples from Berlin (Germany). Effective soil remediation measures are therefore urgently needed.
Recently we demonstrated the technical and economic feasibility of the novel chelant-based soil washing technology for remediation of toxic metal contaminated soils. In this novel technology the chelant (ethylenediamine tetraacetate, EDTA) and process water recycling relies on a combination of substitution/ precipitation reactions in an imposed pH gradient for EDTA recovery, and on electrochemical polishing of process waters for total water recycle in a closed loop. Multi-metal (Pb, Zn and Cd,) contaminated soil from Meza Valley, Slovenia was used as a model. However, before accepted novel technology need to be evaluated for widely different types of urban and peri-urban soils and variety of metal and semi-metal contaminants. Even though EDTA-remediated soil effectively lowers the human health risk could soil deprived of micronutrients and most of the microbial life due to stringent chemical extractions be suitable for plant cultivation and agricultural use? What measures are needed for revitalization to restore health and reclaim EDTA-remediated soil as a fertile and safe plant substrate? Can EDTA soil washing qualify as green and sustainable remediation method? We will address these issues using a multi-disciplinary approach:
1.) We will remediate (in laboratory and pilot scale) pedologically diverse garden soils from urban locations in Slovenia with different contamination history. Remediation technology will be further developed for As removal, Life Cycle Analysis will be performed.
2.) Effective means of revitalization will be applied to restore health and reclaim EDTA-remediated soil as a fertile and safe plant substrate.
3.) Dynamics of release and accessibility of residual emissions (toxic metals and chelant) in remediated soils will be assessed and risk-management options developed.
4.) Plant (crops, vegetables, grasses, ornamental plants and flowers) performance on remediated soil will be investigated and evaluated against legislative limits (i.e. for safe food).
5.) Remediation technology will be probed against concepts of green and sustainable remediation practices and benchmarked by comparative assessment of the alternative remediation measures.
Results of the project proposed will provide comprehensive information concerning the conditions under which the novel soil remediation technology will be effective. It will show the idea of soil reclamation as an important factor in the concept of sustainable city.
Significance for science
Project results demonstrated the feasibility of novel soil washing technology based on chelating agent EDTA. Novel technology recycles EDTA and all process waters in a closed process loop; there are no wastewaters generated and no potentially toxic emissions from remediated soil. Small amount of solid wastes is potentially reusable in a curricular economy as a raw material. This however will require additional studies. Technology enables removal and permanent reduction of toxicity of potentially toxic metals such are Pb, Zn and Cd and immobilisation of oxy-anion forming toxic elements such is As. The uptake of toxic elements from remediated soil into the plant biomass is significantly reduced. Remediation is feasible for soils with different properties without major intervention on the soil properties, quality and functioning. On July 2011 European Commission (EC) released a paper (Science for Environment Policy, EC, 2011) where the lack of reports and evaluations of soil remediation technologies is addressed. The deficiency in soil remediation technologies is one of the reasons why the EC did not adopt the Soil Framework Directive (COM (2006) 232). This might be attributed to scattered information regarding the application and performance of innovative technologies, lack of knowledge and lack of confidence. Project results fill this gap by providing comprehensive information concerning the conditions under which the novel technology is effective, showing the advantage of soil washing technology compared to conventional options particularly by consideration of sustainability issues in the assessment of remediation effect and safe (urban) gardens, and by showing the idea of soil reclamation as an important concept in a sustainable city.
Significance for the country
Under the pressure of civil movements and non-governmental organizations the parliament of Slovenian Republic recently adopted legislature to proclaim the wider area of city Celje as environmentally degraded because of the problems with contaminated soils. The industrial area of Meza valley and cities of Jesenice nad Litija are facing very similar problems. Hot spots of Pb contamination can be found in urban areas with the past intensive traffic for example in Domžale and Ljubljana. Availability of efficient soil remediation technologies and reclamation of contaminated land is a powerful tool to revitalize these largely urban degraded areas. Innovative technologies have to prove their applicability at the lab, pilot, and demonstration scales. The project partner Envit Ltd is a leading partner in Life+ project ReSoil. In this scope a demonstrational soil remediation facility was constructed in city of Prevalje in Meza Valley. The plant operates based on patented technology developed in part in this project. Very few innovative, sustainable remediation technologies received recognition at the European market, while in practice, conventional non-sustainable soil remediation technologies (i.e. “dig and dump”) still prevail. The main barriers to the uptake of alternative soil remediation technologies are cost, lack of confidence in their effectiveness and a lack of general understanding. The results of the project will rises the confidence in novel soil washing technology.
Most important scientific results
Annual report
2014,
2015,
final report
Most important socioeconomically and culturally relevant results
Annual report
2014,
2015,
final report
