A double-bed process for the removal of cationic fission products from milk

Abstract

SummaryA process for the removal of cationic fission products from milk is described in which no prior acidification is necessary. The milk is treated at 40°C by 2 beds of suitably charged cation exchange resins, one of which is of the carboxylic acid type and the other of the sulphonic acid type. On the first bed all the metallic cations of the milk are replaced by K+and H+, and on the second the ioniccomposition is restored. During processing the pH is reduced from 6·8 to approximately 6·2 and is restored to 6·8 by the addition of alkali metal carbonates to the milk after treatment.On a pilot plant of capacity 1600 1 (30 resin bed volumes) per 5-h day it was found that the radiochemical efficiency was approximately 80% for85Sr and 97% for137Cs.The process caused some losses of vitamins, especially of thiamine, and an increase in the lead, copper and iron contents all of which, however, were at an acceptable level. Other changes in chemical composition were negligible and enzymic clotting time remained unchanged. Flavour and appearance of the product were satisfactory and it was satisfactorily both roller- and spray-dried. The process is discussed with reference to an earlier method in which prior acidification is necessary. It is concluded that the double-bed process is somewhat more efficient for the removal of fission products and that a full-scale plant would be little or no more expensive to erect and only slightly more expensive to operate.