Demonstration and application of remediation practices and technologies on the uranium tailings of Kadzhi Say technogenic area
Tech Area / Field
- CHE-POL/Polymer Chemistry/Chemistry
- CHE-SAS/Safety and Security/Chemistry
- ENV-RED/Remediation and Decontamination/Environment
3 Approved without Funding
National Academy of Sciences of Kyrgyzstan / Institute of Chemistry and Chemical Technology, Kyrgyzstan, Bishkek
- University of Tsukuba, Japan, Tsukuba
Project summaryThe goal of this project is to test the approaches and technology developed in frame of completed by our team ISTC projects (KR-964, KR-1316, KR-993.2, KR-2093; KR-2092) and available to determine the key characteristics of the tools and methods that could be included in regional decontamination toolkit. It will intend, wherever possible, to determine quantitative features that allow trade-off between different approaches to be determined - efficiency of decontamination, time required, costs and special equipment/specialist manpower needs, operational safety, environmental impact, waste management requirements and public acceptance. We will focus on technogenic area of Kyrgyzstan: the former uranium-producing province - Kadzhi-Say.
In Kadzhi-Say area the total radiation dose is about 200-300 mR/h on average of which 25-40 mR/h resulted from external radiation. This natural background varies considerably as a result of local geology and altitude. The contaminated areas within the technogenic zones clearly have radiation levels well above background (Project KR-2092). The critical features of this place are:
· the inventory of radionuclides released as a function of time;
· the area is highly exposed to the erosion due to its location in the lower catchment area of a highly technogenically eroded watershed;
· highly degraded soils with fragmented bushes and grasses are featuring the current state of local ecosystem. Sandy winds are usually spreading out the material of uranium tailing’s cover to the East and West from the site, while extensive water erosion through temporary drains are exporting contaminated materials northward down to the direction of the Lake of Issyk- Kul.
It will intend that the experience gained will contribute towards developing a more integrated methodology for subsequent work to be performed during scale decontamination.
Project participants have extensive work experience on the establishment of ecologically safe technologies for remediation of xenobiotic polluted soils e.g., ISTC projects #KR-964, #KR-993.2, #KR-1316, #KR-2092, #KR-2093.
The obtained results in frame of KR-964 project demonstrated clearly that humic preparations applied as detoxifying agents towards copper were able to detoxify soil polluted with that heavy metal even after two vegetation seasons after soil treatment with humics. On the other hand, detoxifying ability of humics was shown to be determined by both their binding ability towards metal and own mitigating activity. Finally, obtained results were evident for that humic preparations did not influence on copper mobility in soil.
Both the fundamental research data and practical application of polymeric binders, i.e. non-stoichimetric interpolyelctrolyte complexes (NIPECs) obtained in frame of KR-2093 demonstrated that NIPECs are effectively bound to soil particles and cannot be washed away with rainfall, or artificial irrigation, or water from melted snow. Additionally, NIPECs are able to bind effectively a majority of toxic metals due to incorporation of metals inside hydrophobic NIPEC fragments generated by mutually neutralized cationic and anionic units. As a result, thermodynamically stable structures are formed with a central metal ion surrounded by functional groups of both polyelectrolytes.
Based on the conducted experiments in frame of KR-993.2, a collection of natural humic substances and microorganisms isolated from the rhizosphere of weed - couch-grass Elytrigia repens that produce novel, natural metabolites (PGPR, plant growth promoting rhizobacteria) that actively promote plant growth have been elaborated. Currently, phytoremediation technologies are not used in Kyrgyzstan. A key point during the development of phytoremediation technology includes the introduction of a suitable plant species that is adapted and capable to grow in heavily polluted sites, in particularly couch-grass The technology has the potential to be profitable due to the inherent climatic characteristics of the Republic. The Kyrgyz climate allows for a long vegetative period of plants and goes from March till November, thus favoring optimal conditions for soil microflora development.
However, all technology has been tested to date only on a laboratory scale. But, the scientific merit of the results obtained in frame of indicated projects provides unambiguous arguments for the success of its innovative part. The new technologies are proposed, they are well backed up by the laboratory synthetic data, the chemical and biological tests of the quality of the product synthesized under laboratory conditions are conducted and proved its high efficiency. This indicates that the project results are ready for launching innovative part of the research that includes scaling up of the developed technology, production, and field testing of the product. Full-scale realization of the innovative part of the projects is a prerequisite for further commercialization of the developed technologies which provide for sustainability of the projects - a final and main goal of ISTC.
Developed techniques will be trialed, such as the application of special decontamination adsorbents (e.g. humics-based), polymer complexes including humics, phytoremediation based on symbiotic preparations including rhizosphere microorganisms and humics. Many of the different techniques will be tested side by side on the same surfaces, in order to directly compare the decontamination effectiveness of different methodologies.
The decontamination pilot project will provide a good basis for developing recommendations on how to assure decontamination efficiency and worker safety whilst additionally constraining costs, subsequent waste management and environmental impacts. The decontamination project will thus be play a key role in the drafting of guidelines and manuals that can be used as a source of reference for the contractors performing decontamination.