Simultaneous Removal of Selected Oxidized Contaminants from Groundwater with a Hydrogen based Membrane Biofilm Reactor

Abstract:

A hydrogen based membrane biofilm reactor (MBfR) was applied for simultaneous biodegradation of selected oxidized contaminants in groundwater including nitrate (NO-3N), sulfate (SO2-4), bromate (BrO-3), chromate (Cr(Ⅵ)) and para chloronitrobenzene (pCNB). The autohydrogentrophic bacteria lived on the membrane surface bioreduced nitrate to N2, sulfate to sulfide (S2-/HM2S), bromate to bromide ion (Br-), Cr(Ⅵ) to Cr(Ⅲ) and pCNB to pCAN and AN with hydrogen as electron donor. Removal and/or toxicity decrease of these oxidized contaminates was achieved through biological reduction. After biofilm enrichment and 32 d continuous running, the reactor reached a steady state for removing oxidized contaminates with a nearly complete removal for nitrate and bromate, 19.8% for sulfate, 85.6% for chromate, and 86.1% for pCNB, under the hydrogen pressure at 0.06 MPa and hydraulic retention time at 4.67 h. The results show that the MBfR technology can be effective for removal of oxidized contaminates and of a potential application in the treatment of groundwater.