Methods for storage and disposal of residues from wastewater treatment of former uranium mining and milling facilities in Germany

In connection with the flooding of uranium mines in Saxony and Thuringia, there are contaminated pit waters that must be purified before discharge into surface waters. The expected duration of the water purification process until concentrations of natural radionuclides, various heavy metals and arsenic are low enough to allow direct discharge into surface waters amounts to decades . To prevent or minimize the leaching of the contaminants from the sludge of the water treatment in the long term, the contaminants are either transformed into chemical compounds of low solubility or affixed within ion exchange resins. Due to the accumulation of those contaminants during the water processing procedure, the residua must be disposed of for reasons of radiation protection and waste management. A final storage of the residua in accord with nuclear regulatory stipulations is unnecessary because of the contamination levels and also because of the mining origin. The method of residua-storage chosen to be best suited to a particular site has to be based on costs-to-benefit analyses, giving due consideration to the different aspects e.g. radiation and environmental protection, long term safety, form of immobilization, site specific conditions. These methods will be described and illustrated using specific examples of applications. (author)