Summary
Wastewaters from the Wismut GmbH plant on the Helmsdorf site have a characteristic feature: as a result of soda alkali treatment, the principle pollutant, uranium, is present in the form of a “carbonate complex”. No directly applicable passive treatment methods for waters of this composition have been available hitherto.
The key focus of this project was the development and selection of appropriate materials for the in-situ separation of uranium, arsenic and radium, together with the modelling of separation behaviour in reactive walls and the dimensioning of a reactive wall for a pilot plant.
Results:
- For the separation of radium and arsenic, reactive materials have been selected or developed which provide cost-effective solutions for the treatment of groundwater and surface waters (“Hedulat”: geopolymer-bonded barium sulphate; “Ferrosorp”: iron hydroxide granulate).
- Nonvalent iron (sponge iron) and granulated industrial peat will only be effective for the passive separation of uranium.
- Where sponge iron is used, the efficiency of separation will be inversely proportional to the uranium concentration in the water to be treated.
- The capacity of granulated industrial peat is rapidly exhausted, thereby necessitating the frequent replacement of the reactive material.
- A model has been developed for the description of separation behaviour which satisfies all technical requirements.
- Costs for the in-situ treatment of contaminated groundwater using permeable reactive walls range from 1 to 7 Euros/m3. Costs are dependent upon the uranium and bicarbonate concentrations.
