A Review of Manganese-Oxidizing Bacteria (MnOB): Applications, Future Concerns, and Challenges.

Groundwater serving as a drinking water resource usually contains manganese ions (Mn) that exceed drinking standards. Based on the Mn biogeochemical cycle at the hydrosphere scale, bioprocesses consisting of aeration, biofiltration, and disinfection are well known as a cost-effective and environmentally friendly ecotechnology for removing Mn. The design of aeration and biofiltration units, which are critical components, is significantly influenced by coexisting iron and ammonia in groundwater; however, there is no unified standard for optimizing bioprocess operation. In addition to the groundwater purification, it was also found that manganese-oxidizing bacteria (MnOB)-derived biogenic Mn oxides (bioMnO), a by-product, have a low crystallinity and a relatively high specific surface area; the MnOB supplied with Mn can be developed for contaminated water remediation. As a result, according to previous studies, this paper summarized and provided operational suggestions for the removal of Mn from groundwater. This review also anticipated challenges and future concerns, as well as opportunities for bioMnO applications. These could improve our understanding of the MnOB group and its practical applications.