title: Denitrification of drinking water in a two-stage membrane bioreactor by using immobilized biomass.
abstract: Nitrate removal from polluted groundwater was investigated in a two-stage anoxic/oxic biofilm membrane bioreactor. The process was carried out with ethanol as a carbon source (corresponding C/N ratio of 1.4-2.5) and commercially available Biocontact-N biocarriers (Nisshinbo, Japan) to enable immobilization of highly efficient and long-lasting microbiota. At a residence time of the liquid phase equal to 2.5h, nitrate conversions higher than 99% were obtained without the formation of nitrite and ammonium ions. The concentration of total organic carbon in the reactor discharge was very similar to the content of organic matter in tap water. The biocarriers minimized the occurrence of suspended filamentous bacteria, and the utilization of increased shear force facilitated collisions of floating biocarrier particles with the outer membrane surface, preventing membrane fouling and resulting in stable operation of the system for 40 days.
authors.affiliation: HTZ Velenje, IP, doo, Partizanska cesta 78, SI-3320 Velenje, Slovenia.
authors.forename: Matjaž
authors.initials: M
authors.lastname: Ravnjak
authors.forename: Janez
authors.initials: J
authors.lastname: Vrtovšek
authors.forename: Albin
authors.initials: A
authors.lastname: Pintar
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D018914:Cells, Immobilized; D058440:Denitrification / Q000502:physiology; D060766:Drinking Water / Q000382:microbiology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D000431:Ethanol / Q000378:metabolism; D008567:Membranes, Artificial; D009566:Nitrates / Q000302:isolation & purification / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification / Q000378:metabolism; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; D008567:Membranes, Artificial; D009566:Nitrates; D014874:Water Pollutants, Chemical; D000431:Ethanol