THE REMOVAL OF METALLIC IONS BY FOAMING AGENTS AND SUSPENSIONS: LABORATORY AND ENGINEERING STUDIES. Annual Report, July 1, 1962 to June 30, 1963

A two-stage process, consisting of a head-end scavenging precipitation to reduce the Ca/sup 2+/ and Mg/sup 2+/ concentrations followed by a countercurrent foam separation column, for removing Sr/sup 2+/ and Cs/sup +/ from low-activity, high-volume waste solutions was successfully demonstrated in small scale equipment. Radioactive Sr was removed to the extent that its concentration in the effiuent from the process was well below the maximum permissible concentration for water. It was found that 90% or more of the Cs can be removed by addition of grundite clay to the head-end precipitator. Important factors involved in this demonstration include ratio of height to diameter of sludge bed (which can be less than 1); precipitant, the most satisfactory being NaOH and Na/ sub 2/CO/sub 3/, each at a concentration of 0.005M in the water; flow rate in the sludge bed, which was increased to 26.5 gal ft/sup -2/ hr/sup -1/ to date; surfactant and its concentration in the foam column; effect of pH and the extent of Ca/sup 2+/ and Na/sup +/ interference in removal of Sr/sup 2+/ and Cs/sup +/ by foaming; and several foam column parameters, including liquid throughput rate, which was increased to 120 gal ft/sup -2/ hr/sup -1/,more » gas to liquid flow ratio, and Sr decontamination factor, which varied from approximates 3 to approximates 5000 in these experiments. Of the nine most promising surfactants for this process, most experiments were performed with- sodium dodecylbenzene suifonate (as Siponate DS-10 or Trepolate F-95), or Tergitol 7, By measuring the dependence of the foam density on the linear foam rate a relation between distribution factor, feed throughput rate, and volume reduction, applicable when the decontamination is 100 or more, was established. Other mathematical studies were used to show the variation of the maximum decontamination factor with the ratio of gas flow rate to feed flow rate and bubble diameter (G/F. D). (auth)« less