Development of a Recycling Purification Method for Heavy Water Media After Microbial Cultivation

Abstract

Heavy water (D₂O) is an indispensable material not only in chemical research for studies of isotope effects but also in biology and drug discovery, where it is extensively utilized for applications such as microbial cultivation. However, the rising cost of D₂O has made its large-scale procurement increasingly challenging. Consequently, the development of technologies for the purification and recycling of used heavy water has garnered considerable attention. Heavy water from chemical research typically contains relatively simple impurities and can be purified effectively. In contrast, D₂O used as a microbial culture medium becomes contaminated with a wide variety of metabolic byproducts, making it difficult to achieve sufficient purity with conventional methods that combine activated carbon treatment and distillation. Furthermore, subsequent enrichment of purified D₂O via electrolysis demands exceptionally high purity with minimal impurities. In this study, we developed a highly efficient purification method incorporating Fenton oxidation and the formation of charged borate complexes. This process yielded high-purity heavy water with an electrical conductivity lower than that of standard tap water in Japan.