title: Evaluation of the resilience of a full-scale down-flow hanging sponge reactor to long-term outages at a sewage treatment plant in India.
abstract: Resilience to process outages is an essential requirement for sustainable wastewater treatment systems in developing countries. In this study, we evaluated the ability of a full-scale down-flow hanging sponge (DHS) reactor to recover after a 10-day outage. The DHS tested in this study uses polyurethane sponge as packing material. This full-scale DHS reactor has been tested over a period of about 4 years in India with a flow rate of 500 m(3)/day. Water was not supplied to the DHS reactor that was subjected to the 10-day outage; however, the biomass did not dry out because the sponge was able to retain enough water. Soon after the reactor was restarted, a small quantity of biomass, amounting to only 0.1% of the total retained biomass, was eluted. The DHS effluent achieved satisfactory removal of suspended solids, chemical oxygen demand, and ammonium nitrogen within 90, 45, and 90 min, respectively. Conversely, fecal coliforms in the DHS effluent did not reach satisfactory levels within 540 min; instead, the normal levels of fecal coliforms were achieved within 3 days. Overall, the tests demonstrated that the DHS reactor was sufficiently robust to withstand long-term outages and achieved steady state soon after restart. This reinforces the suitability of this technology for developing countries.
authors.affiliation: Department of Regional Environmental Research Center, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. Electronic address: onodera.takashi@nies.go.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Onodera
authors.affiliation: Department of Civil and Environmental Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takayama
authors.affiliation: Department of Social and Environmental Engineering, Hiroshima University, 1-4-1 Kagamiyama Higashi, Hiroshima 739-8527, Japan. Electronic address: ecoakiyo@hiroshima-u.ac.jp.
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Ohashi
authors.affiliation: Department of Civil and Environmental Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan. Electronic address: ecoya@vos.nagaokaut.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Social and Environmental Engineering, Hiroshima University, 1-4-1 Kagamiyama Higashi, Hiroshima 739-8527, Japan; Department of Civil and Environmental Engineering, National Institute of Technology, Kisarazu College, 2-11-1 Kiyomidaihigashi, Kisarazu, Chiba 292-0041, Japan. Electronic address: uemura@wangan.c.kisarazu.ac.jp.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Uemura
authors.affiliation: New Industry Creation Hatchery Center, Tohoku University, 6-6-04 Aoba, Aramakiaza, Aoba-ku, Sendai, Miyagi 980-8579, Japan. Electronic address: hideki.harada.e3@tohoku.ac.jp.
authors.forename: Hideki
authors.initials: H
authors.lastname: Harada
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000818:Animals; D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D004867:Equipment Design; D005243:Feces / Q000382:microbiology; D007194:India; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D011140:Polyurethanes; D012722:Sewage / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000295:instrumentation* / Q000379:methods; D062065:Wastewater
chemical_list: D000641:Ammonia; D009584:Nitrogen; D011140:Polyurethanes; D012722:Sewage; D062065:Wastewater
keywords: Developing countries; Down-flow hanging sponge (DHS); Process outage; Starvation conditions; Sustainable wastewater treatment