Tritium Elimination System Using Tritium Gas Oxidizing Bacteria

Hydrogen-oxidizing bacteria and their applications in resource recovery and pollutant removal

Hydrogen oxidizing bacteria (HOB), a type of chemoautotroph, are a group of bacteria from different genera that share the ability to oxidize H₂ and fix CO₂ to provide energy and synthesize cellular material. Recently, HOB have received growing attention due to their potential for CO₂ capture and waste recovery. This review provides a comprehensive overview of the biological characteristics of HOB and their application in resource recovery and pollutant removal. Firstly, the enzymes, genes and corresponding regulation systems responsible for the key metabolic processes of HOB are discussed in detail. Then, the enrichment and cultivation methods including the coupled water splitting-biosynthetic system cultivation, mixed cultivation and two-stage cultivation strategies for HOB are summarized, which is the critical prerequisite for their application. On the basis, recent advances of HOB application in the recovery of high-value products and the removal of pollutants are presented. Finally, the key points for future investigation are proposed that more attention should be paid to the main limitations in the large-scale industrial application of HOB, including the mass transfer rate of the gases, the safety of the production processes and products, and the commercial value of the products.

Experimental investigation on feasible bioreactor using mechanism of hydrogen oxidation of natural soil for detritiation system

A passive reactor for tritium oxidation at room temperature has been widely studied in nuclear engineering especially for a detritiation system (DS) of a tritium process facility taking possible extraordinary situation severely into consideration. We have focused on bacterial oxidation of tritium by hydrogen-oxidizing bacteria in natural soil to realize the passive oxidation reactor. The purpose of this study was to examine the feasibility of a bioreactor with hydrogen-oxidizing bacteria in soil from a point of view of engineering. The efficiency of the bioreactor was evaluated by kinetics. The bioreactor packed with natural soil shows a relative high conversion rate of tritium under the saturated moisture condition at room temperature, which is obviously superior to that of a Pt/Al2O3 catalyst generally used for tritium oxidation in the existing tritium handling facilities. The order of reaction for tritium oxidation with soil was the pseudo-first order as assessed with Michaelis-Menten kinetics model. Our engineering suggestion to increase the reaction rate is the intentional addition of hydrogen at a small concentration in the feed gas on condition that the oxidation of tritium with soil is expressed by the Michaelis-Menten kinetics model.