Abstract
The volume reduction of radioactive sludges is one of the most important problems involved in the large scale treatment of weakly contaminated liquid wastes through flocculation. A small plant has been constructed at the Radiation Center of Osaka Pref. in March of 1962, which is the first attempt in Japan that adopts the freezing treatment for concentrating radioactive sludges. The volume reduction characteristic of this plant has been investigated. This plant can handle 125l of sludge per day and can reduce the final volume of the concentrated sludge to about 1/5, 000, 1/2, 000 and 1/4, 000 of the volume of the original waste water to be decontaminated, for bentonite-Konan Floc sludge, calcium phosphate sludge and ferric hydroxide sludge, respectively, in the case that the separation by settling is applied as the treatment after thawing. Appreciably higher volume reduction ratio can be obtained when the vacuum filtration is applied after thawing. In the beaker-experiments which were carried out before the present investigation, it was found that the addition of some polymer as agent is effective in improving the volume reduction or in shortening the settling time after thawing. This finding has been applied for the large scale treatment by this plant and good results as expected have been obtained.
