Selenate removal from waste water

摘要

A method and apparatus for removing selenate from waste water through the use of selenate respiring microorganisms under substantially anoxic conditions is described. The method includes a first zone for removing nitrate by assimilation into biomass. The first zone is maintained under aerobic conditions and is separated from a second zone where selenate is respired to elemental selenium by selenate respiring microorganisms under anoxic conditions. Biomass produced in the first zone may be processed to provide nutrients and electron acceptors for the maintenance of selenate respiring microorganisms when selenate becomes growth limiting. An optional sulfate reduction zone is provided in the method and apparatus where hydrogen sulfide is produced. The hydrogen sulfide so produced is circulated to the second zone and may be used to reduce residual selenite to elemental selenium.