title: Recovery of partial nitrification in a down-flow hanging sponge reactor by salt shock loading.
abstract: Partial nitrification of ammonium-containing artificial wastewater was achieved using a down-flow hanging sponge (DHS) reactor with a hydraulic retention time (HRT) of 2 h by adjusting the influent salinity to 25 g Cl L(-1) with NaCl. The effect of HRT on partial nitrification was examined by varying HRT from 1 to 4 h. Extending HRT from 2 to 4 h had the effect of decreasing nitrite production and increasing nitrates. Since partial nitrification was not completely recovered after returning the HRT to 2 h, we examined the effect of salt shock loading on the recovery of partial nitrification. Salt shock loading with 150 gCl L(-1) for 72 h resulted in the fraction of NO2-N to total inorganic nitrogen in the effluent reaching 83.0% as much as 83 days after returning the salinity to the original level. Thus, despite the time required for the restoration of partial nitrification, the effectiveness of salt shock loading to achieve this aim was verified.
authors.affiliation: a Department of Civil Engineering , Tohoku University, Aramaki, Aoba-ku , Sendai , Miyagi , Japan.
authors.forename: Miri
authors.initials: M
authors.lastname: Matsubayashi
authors.affiliation: b New Industry Creation Hatchery Center, Tohoku University, Aramaki, Aoba-ku , Sendai , Miyagi , Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Harada
authors.affiliation: c Kisarazu College, National Institute of Technology , Kisarazu , Chiba , Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Okubo
authors.affiliation: c Kisarazu College, National Institute of Technology , Kisarazu , Chiba , Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Uemura
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry; D000818:Animals; D058465:Nitrification; D009573:Nitrites / Q000737:chemistry; D011161:Porifera / Q000737:chemistry*; D054712:Salinity; D012965:Sodium Chloride / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D064751:Ammonium Compounds; D009573:Nitrites; D012965:Sodium Chloride; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: DHS; partial nitrification; recovery; salinity; salt shock loading