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Projects / Programmes source: ARIS

Remediacija s kovinami onesnaženih tal v Mežiški dolini z uporabo ligandov in elektrokemijskih naprednih oksidacijskih procesov (Slovene)

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Research activity

Code Science Field Subfield
1.08.00  Natural sciences and mathematics  Control and care of the environment   

Code Science Field
1.05  Natural Sciences  Earth and related Environmental sciences 
Evaluation (rules)
source: COBISS
Evaluation of bibliographic research performance indicators according to ARIS methodology
Citations Citations for bibliographic records in COBIB.SI that are linked to records in citation databases
source: WoS source: Scopus source: COBISS
Researchers (9)
no. Code Name and surname Research area Role Period No. of publications
1.  31478  Maša Čarf  Biology  Technical associate  2009  20 
2.  29418  PhD Maja Čič  Control and care of the environment  Junior researcher  2009 - 2012  43 
3.  11155  PhD Damjana Drobne  Biology  Researcher  2011 - 2012  861 
4.  25506  PhD Neža Finžgar  Plant production  Junior researcher  2009 - 2010  86 
5.  08259  PhD Domen Leštan  Plant production  Head  2009 - 2012  408 
6.  17780  Viljem Šijanec    Technical associate  2011 - 2012  0 
7.  26538  PhD Metka Udovič  Plant production  Researcher  2009 - 2010  57 
8.  31993  PhD David Voglar  Control and care of the environment  Junior researcher  2011 - 2012  19 
9.  31120  PhD Grega Ernest Voglar  Control and care of the environment  Researcher  2009 - 2010  41 
Organisations (1)
no. Code Research organisation City Registration number No. of publications
1.  0481  University of Ljubljana, Biotechnical Faculty  Ljubljana  1626914  66,279 
Significance for science
There are more than 1.8 million contaminated sites in western central and south-eastern Europe, of which 240,000 are in need of remedial treatment. The proper remediation and management of toxic metals contaminated soil has been a widespread and costly issue. The selection of appropriate remediation technology depends on the contamination and soil type and final use of the reclaimed land. Soil washing with an aqueous solution of chelating agents, usually ethylenediaminetetraacetate (EDTA), is considered to be a remedial option with a potentially low impact on soil quality. Demonstrated on a laboratory level, but not available commercially, there have been several proposals of how to recycle spent EDTA from the used washing solution. Toxic metals can be separated from EDTA with Na2S under alkaline conditions, resulting in almost complete recovery of metals through precipitation in the form of insoluble metal sulphides. Zero-valent bimetallic mixtures (Mg0-Pd0, Mg0-Ag0) can also be used to precipitate metals from the solution, while liberating EDTA in alkaline pH. Electrolytic recovery of toxic metals and EDTA from washing solution in a two-chamber electrolytic cell separated with a cation exchange membrane to prevent EDTA anodic oxidation has been reported. EDTA can also be recycled by substituting toxic metals with Fe3+ under acidic conditions, followed by precipitation of the released metals with phosphate at near neutral pH. Fe3+ ions are then precipitated as hydroxides at high pH using NaOH, thus liberating the EDTA. In addition to EDTA recycling, the generation of large amounts of waste water after soil washing, which needs treatment before safe disposal, has long remained an unsolved problem. In this project we proposed and tested in laboratory and in a pilot scale an electrochemical process where toxic metals and EDTA are separated in an electrolytic cell under alkaline conditions using a sacrificial Al anode. Al substitutes the toxic metal in complex with EDTA and the released metals are removed by electro-precipitation/coagulation. The remaining EDTA and metals in the waste solution were removed using an electrochemical advanced oxidation process to yield clean process water. Most studies on EDTA-based soil washing focus on the effectiveness of toxic metal removal. However, the bio-availability of metals still remaining in the washed soil and the effect of the remediation process on soil properties and functioning as a plant and microbial (consequently soil fauna) substrate are the factors that finally decide the success or failure of soil washing and other remediation technologies. There was no scientific literature on the effect of EDTA-soil washing on soil properties. For the first time results of this project indicate that remediation using novel soil-washing technology while successfully reduced (eco)toxicity of contaminated soils largely preserved pedological, physico-chemical and biological soil properties and soil functioning as a plant and microbial substrate.
Significance for the country
Soil pollution with toxic metals, for example with lead (Pb) is ubiquitous environmental problem worldwide. In Slovenia critical concentrations of toxic metals in soil were measured in Meza Valley, in wider Celje and Litija districts, along highways and areas with high traffic density such are urban centers. Soils are the final depository of toxic metals and become themselves, after cassation of industrial, agronomical and pollution from traffic, the source of pollution posing health hazard to human populations which are in closed contact or exposed to contaminated soil. In Slovenia one of the most affected locations is Meza Valley, historically contaminated from Pb mining and smelting industry which commenced in 1665 and continued until 1994. Until the second half of 19. century mines and smelters were small and scattered through the Valley. In 1893 new centralised smelting plant was build in the city of Zerjav and Pb production peaked with 27763 tons in year 1977. First systems of filters to decrease dust emissions were installed in 1923 and were further improved in years 1954, 1964 and finally in 1978 after which the daily quantity of released dust was reduced from 5000 to 70 kg. Soils from Meza Valley are now the most significant source of secondary contamination by Pb and also of Zn and Cd. Indeed, experimental evidences are pointing toward significant correlation of Pb blood level in of 3-years old children and concentration of Pb in house dust and soil around their residences. Alarmed by data on elevated Pb concentration in blood of small children Slovenian government in 2007 initialized Meza Valley restoration program which encompassed risk awareness education of local population, improvement of hygiene standards in kinder-gardens, road asphalting and dust control, and limited capping of contaminated areas with 5-10 cm layer of non-polluted soil. The later measure was disputed since at least 40-60 cm layer of new soil was reported to be efficient. Despite accepted measures results of annual surveys of Pb blood concentration indicated that the number of children with levels higher than 100 ng L-1, stipulated by Slovenian legislation as hazardous did not decline nor change significantly during the 6-year period of restoration program. In parallel with Meza Valley site restoration program Slovenian Research Agency has been funding projects aiming to develop efficient remediation technology for permanent removal of Pb and co-contaminating metals from Meza soils. Several approaches were tested: phytoextraction and chemically-induced phytoextraction with different plants and soil extraction with acid were proved not to be efficient and the later has also distinctly negative impact on soil properties. Soils form Meza Valley predominantly contain high content of organic mater, clay and silt therefore physical separation (i.e. in hydrocyclones) of contaminated fines from relatively non-contaminated bulk soil is also not feasible. On the other hand results of the current project provided experimental evidence that soil washing using chelating agent ethylenediamine tetraacetate (EDTA) efficiently removed toxic metals from soil and permanently reduced bioaccessibility and bioavailability of residual toxic metals in Meza soils. Results of the current project also confirmed quite minor effect of the proposed remediation technology on properties and health of soil as a plant substrate. Finally, results of the pilot-scale testing proved technical and economic viability of the novel technology. The novel remediation technology provides for permanent solution of soil contamination in Meza Valley and should be included into ongoing Meza Valley restoration program as the most urgent and vital component.
Most important scientific results Annual report 2009, 2010, 2011, final report, complete report on dLib.si
Most important socioeconomically and culturally relevant results Annual report 2009, 2010, 2011, final report, complete report on dLib.si
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