Protection of biomass from snail overgrazing in a trickling filter using sponge media as a biomass carrier: down-flow hanging sponge system.
This study investigated down-flow hanging sponge (DHS) technology as a promising trickling filter (TF) using sponge media as a biomass carrier with an emphasis on protection of the biomass against macrofauna overgrazing. A pilot-scale DHS reactor fed with low-strength municipal sewage was operated under ambient temperature conditions for 1 year at a sewage treatment plant in Bangkok, Thailand. The results showed that snails (macrofauna) were present on the surface of the sponge media, but could not enter into it, because the sponge media with smaller pores physically protected the biomass from the snails. As a result, the sponge media maintained a dense biomass, with an average value of 22.3 gVSS/L sponge (58.1 gTSS/L sponge) on day 370. The snails could graze biomass on the surface of the sponge media. The DHS reactor process performance was also successful. The DHS reactor requires neither chemical treatments nor specific operations such as flooding for snail control. Overall, the results of this study indicate that the DHS reactor is able to protect biomass from snail overgrazing.
Center for Regional Environmental Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan E-mail: onodera.takashi@nies.go.jp.
Takashi
T
Onodera
Center for Regional Environmental Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan E-mail: onodera.takashi@nies.go.jp.
Kazuaki
K
Syutsubo
Department of Environmental Engineering, Faculty of Engineering, King Mongkut's University of Technology Thonburi (KMUTT), 126 Pracha Uthit Road, Bang Mod, Thung Khru, Bangkok 10140, Thailand.
Wilasinee
W
Yoochatchaval
Department of Civil Engineering, Gifu National College of Technology (GNCT), 2236-2 Kamimakuwa, Motosu, Gifu 501-0495, Japan.
Haruhiko
H
Sumino
Center for Regional Environmental Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan E-mail: onodera.takashi@nies.go.jp.
Motoyuki
M
Mizuochi
Department of Civil and Environmental Engineering, Tohoku University, 6-6-06 Aoba, Aramakiaza, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
Hideki
H
Harada
D000818:Animals; D018533:Biomass; D019149:Bioreactors; D005374:Filtration / Q000295:instrumentation*; D012722:Sewage; D012908:Snails / Q000502:physiology*; D013785:Thailand
D012722:Sewage