SummaryDetritiation of contaminated water is an essential part of nuclear power production. Most promising methods used for this process are based on catalyzed hydrogen isotope exchange reactions. It is proposed herein to replace the platinum catalysts which are currently used in industry with immobilized hydrogenase. Whole bacterial cells of Alcaligenes eutrophus immobilized in calcium alginate or K-carrageenan gels were found to be efficient catalysts of the reaction of hydrogen-tritium (H-T) exchange in both a batch tank reactor and in a column. The dependence of the reaction rate on the amount of immobilized cells in the system, and on the concentration of the cells in the matrix, indicate that enzymatic H-T exchange is not controlled by diffusion. Immobilized A . eutrophus cells are enzymatically active over a wide range of pH, with a broad maximum from pH 6.0 to 8.0, and are quite resistant to inhibitors of hydrogenases such as Oz and CO. Upon increasing the temperature from 4 to 37"C, the rate of hydrogenase-catalyzed H-T exchange increases by a factor of 5. From the standpoint of catalytic efticiency, 1 g of PtO, is approximately equivalent to 10 g of cells (wet weight). In contrast to platinum-based catalysts, bacterial hydrogenases I) are potentially inexpensive; 2) can be readily available in bulk quantities; 3) are maximally active in liquid water.

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