The removal of selenate to low ppb levels from flue gas desulfurization brine using the H2-based membrane biofilm reactor (MBfR)

The H2-based membrane biofilm reactor (MBfR) was shown to consistently remove nitrate, nitrite, and selenate at high efficiencies from flue-gas desulfurization brine. Selenate was removed to <50 ppb which is the National Pollutant Discharge Elimination System (NPDES) criteria for the brine to be released into the environment. When selenate was removed to <50 ppb, nitrate and nitrite were still present in the mg/L range which suggests that selenate is able to be secondarily reduced to low levels when nitrate and nitrite serve as the main electron acceptors for bacterial growth. SO 4 2 - was not removed and therefore did not compete with nitrate and selenate reduction for the available H2.