Tritium recovery system by use of tritium gas oxidizing bacteria

一般来说，包括贵金属和金属氧化物的金属催化剂被开发并用于连接到氚处理实验室排气管的氚气回收系统。除了价格昂贵的问题外，还需要进行一些加热和冷却的预处理。本研究旨在利用氚气氧化细菌，发展一种生物反应器，以应用于事故中氚气回收系统。从从不同土壤中分离得到的具有氚气氧化活性（氢化酶）的细菌中，筛选出几株具有较高活性的土壤放线菌，并对其生长条件（包括培养基、培养条件和保存条件）进行了研究。从分离自鸟取沙丘土壤和意大利森林土壤的两株菌中筛选出最适合用于氚气氧化生物反应器的菌株。将这些菌株固定在聚丙烯褶裥滤膜上，用ISP 4琼脂培养基，在30℃下培养10天，制成生物反应器。以鸟取沙丘土分离物为原料制成的生物反应器在30 ℃下保存2个月，其氚气氧化活性基本保持不变，冷藏150天后仍保持约2/3的活性。对氚回收系统中生物反应器在不同气流条件下的容量进行了试验研究，其容量主要取决于气流条件。

In general, metal catalysts including noble metals and metal oxides are developed and used for tritium gas recovery system attached to exhaust pipes of tritium handling laboratories. Some pretreatments of heating and dehumidification are needed for their use except high-priced problem. This study intended the development of a bio-reactor for tritium gas recovery system in an accident by use of tritium gas oxidizing bacteria. Among the bacteria with tritium gas oxidation activity (hydrogenase) isolated from various soils, we chose several soil actinomycete strains with high activity and investigated growth conditions including growth medium, incubation and preservation conditions for their expression of high hydrogenase activity. Two strains, one isolated from Tottori sand dune soil and the other from forest soil from Italy, were chosen as most suitable strains among tested for a bio-reactor of tritium gas oxidation. Bio-reactors were made by fixing these strains on polypropylene pleats filter with ISP4 agar medium and culturing for 10 days at 30℃, respectively. Tritium gas oxidation activity of the bio-reactor made from the isolate from Tottori sand dune soil was almost constantly kept during 2 month's preservation at 3O℃ and about two-thirds of the activity was still kept after 150 days in cold storage. The capacity tests of a bio-reactor in tritium recovery system were examined under different air flow conditions and its capacity primarily depended on flow conditions.