title: Development of a down-flow hanging sponge reactor for the treatment of low strength sewage.
abstract: The process performance of a down-flow hanging sponge (DHS) reactor for treating low strength sewage (biochemical oxygen demand (BOD) 20-50 mg/L) was investigated in Bangkok, Thailand. The hydraulic retention time (HRT) was set at 4 h during the start-up period and was reduced to 1.5 h in a stepwise manner. Throughout the 300-day operational period, the DHS reactor shows high performance with respect to the removal of total suspended solid (>90% total suspended solid removal efficiency). No clogging of sponge media was observed in response to the self-digestion phenomena of the biofilm. At a HRT of 1.5 h, the BOD removal efficiency was sufficiently high (about 85%). The pathogen Escherichia coli and other coliform bacteria were removed almost completely as well (removal was 99.4% and 98.1%, respectively). Regarding the retained sludge activity measurement, the nitrite oxidation rate was higher than the ammonium oxidation rate (0.031 and 0.022 gram of nitrogen per gram of volatile suspended solids per day, respectively). In the 300 days of operation, the amount of excess sludge production was negligible. Thus, no sludge treatment system is required. Introduction of the DHS system in developing countries is recommended because this system requires a relatively small area, and has low electricity consumption and operation costs.
authors.affiliation: Department of Environmental Engineering, Faculty of Engineering, King Mongkut's University of Technology Thonburi, 126 Prachauthid Road, Bangmod, Thungkhru, Bangkok 10140, Thailand E-mail: wilasinee.yoo@kmutt.ac.th.
authors.forename: Wilasinee
authors.initials: W
authors.lastname: Yoochatchaval
authors.affiliation: Center for Regional Environmental Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Onodera
authors.affiliation: Department of Civil Engineering, Gifu National College of Technology, 2236-2 Kamimakuwa, Motosu-city, Gifu 501-0495, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Sumino
authors.affiliation: Department of Environmental System Engineering, Nagaoka University of Technology, 1603-1 Kamitomiokamachi, Nagaoka, Niigata 940-2137, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Center for Regional Environmental Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Mizuochi
authors.affiliation: Center for Regional Environmental Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Okadera
authors.affiliation: Center for Regional Environmental Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Syutsubo
mesh_terms: D000818:Animals; D001419:Bacteria / Q000302:isolation & purification; D018441:Biofilms; D019149:Bioreactors; D009584:Nitrogen / Q000032:analysis; D011161:Porifera; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*; D014873:Water Pollutants / Q000302:isolation & purification
chemical_list: D012722:Sewage; D014873:Water Pollutants; D009584:Nitrogen