Effects of aeration and internal recycle flow on nitrous oxide emissions from a modified Ludzak-Ettinger process fed with glycerol.
Nitrous oxide (N2O) is emitted from a modified Ludzak-Ettinger (MLE) process, as a primary activated sludge system, which requires mitigation. The effects of aeration rates and internal recycle flow (IRF) ratios on N2O emission were investigated in an MLE process fed with glycerol. Reducing the aeration rate from 1.5 to 0.5 L/min increased gaseous the N2O concentration from the aerobic tank and the dissolved N2O concentration in the anoxic tank by 54.4 and 53.4 %, respectively. During the period of higher aeration, the N2O-N conversion ratio was 0.9 % and the potential N2O reducers were predominantly Rhodobacter, which accounted for 21.8 % of the total population. Increasing the IRF ratio from 3.6 to 7.2 decreased the N2O emission rate from the aerobic tank and the dissolved N2O concentration in the anoxic tank by 56 and 48 %, respectively. This study suggests effective N2O mitigation strategies for MLE systems.
Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo, 184-8588, Japan.|Research Fellow of Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan.
Kang
K
Song
Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo, 184-8588, Japan.
Toshikazu
T
Suenaga
Department of Systems Engineering and Management, Air Force Institute of Technology, Wright-Patterson Air Force Base, Dayton, OH, 45433, USA.
Willie F
WF
Harper
National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, 305-8568, Japan.
Tomoyuki
T
Hori
Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo, 184-8588, Japan.
Shohei
S
Riya
Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo, 184-8588, Japan.
Masaaki
M
Hosomi
Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo, 184-8588, Japan. akte@cc.tuat.ac.jp.
Akihiko
A
Terada
D000332:Aerobiosis; D000693:Anaerobiosis; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D005990:Glycerol / Q000737:chemistry*; D009609:Nitrous Oxide / Q000032:analysis*; D059027:Recycling; D016992:Rhodobacter / Q000254:growth & development; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology*
D012722:Sewage; D009609:Nitrous Oxide; D005990:Glycerol
Aeration rate; Glycerol; Internal recycle flow ratio; Microbial community structure; Modified Ludzak–Ettinger processes; N2O-reducing bacteria; Nitrous oxide