A PILOT PLANT FOR REMOVAL OF CATIONIC FISSION PRODUCTS FROM MILK .2. EFFICIENCY OF PROCESS AND COMPOSITION OF PRODUCT

AS previously described, the process consists essentially of the passage of milk at pH 5·2–5·25 through an ion exchange resin charged with a suitable mixture of the ions of Ca, K, Na and Mg. When citric acid was used for reduction of the pH and 30 resin bed volumes (r.b.v.) were treated, the concentration of residual 85Sr was reduced to 2–4% whether it had been introduced in vivo or in vitro. There was no evidence that repeated use of the resin bed resulted in diminished radiochemical efficiency. About the same efficiency of removal of 133Ba was obtained but this efficiency was achieved with 137Cs only if not more than 15 r.b.v. were treated. If 30 r.b.v. were treated the concentration of residual 137Cs was as much as 30%. When hydrochloric acid was substituted for citric acid the residual concentration of 85Sr was 11%. Analyses of milks processed after adjustment of pH with either citric or hydrochloric acid showed the products to be satisfactory. The only important constituent lost was thiamine. Concentrations of heavy metals remained well below maximum values. Although the flavour of milk was detectably changed by the treatment it was still acceptable. The results are discussed in relation to the problem of achieving maximum decontamination and to the design of a large scale plant. © 1968, Proprietors of Journal of Dairy Research. All rights reserved.