Proceedings of CWMD International Conference 2019
September 19-21, 2019, Kumamoto University, Japan

Nitrogen removal and anammox-bacterial community in continuous
reactors inoculated with mixed biomass composed of marine- andfreshwater- anammox bacteria under different culture conditions
Yasunori KAWAGOSHI1, Yuki YAMASHITA2, Hiroaki ITO1, Takehide HAMA1, Luong Van DUC1,Tsuguhiro WATANABE1
1 Center for Water Cycle, Marine Enviroment and Disastar Management, Kumamoto University
2 Kyushukensetsu Consultant Co., Ltd
E-mail: goshi@kumamoto-u.ac.jp
Keywords: anaerobic ammonium oxidation (anammox), marine-anammox bacteria, freshwateranammox bacteria, nitrogen removal, bacterial community
Abstract
Anaerobic ammonium oxidation (anammox) is relatively-new nitrogen oxidation-reduction reaction
discovered in 1995. In anammox, ammonium is oxidized by nitrite under anaerobic condition and both
nitrogen compounds are converted to nitrogen gas. Anammox is catalyzed by anammox bacteria which
are anaerobic autotroph and has been considered to be one of the most important metabolic pathway innitrogen cycle of nature. Commonly, the reaction rate of anammox is considered higher thanconventional nitrification-denitrification reaction and anammox bacteria require no carbon source or
oxygen for their growth. Thus anammox has been expected as a promising reaction to apply to nitrogen
removal technology in wastewater treatment process from the perspective of cost saving. Anammox
bacteria have been detected in various water environments including freshwater and ocean, and divided
broadly into five genera at present. Among five genera of anammox bacteria, four genera are freshwaterderived anammox bacteria (FAB) and only one genus is marine-derived anammox bacteria (MAB). It
has been known that their optimal growth conditions such as temperature and salinity are different, butthere are still unknown in distinction of characteristics between them. Based on this sort of knowledge,
we have attempted to develop a new anammox reactor by combining FAB and MAB in order to achieverobust and flexible nitrogen-removal performance under wide range of operation condition. In this study,
we cultured mixed anammox biomass composed of FAB and MAB in continuous fixed-bed reactors
under three different culture conditions (marine-condition, freshwater-condition, and average-condition)
to reveal nitrogen removal performance and the transition of anammox-bacterial community. As a result,stable nitrogen removal efficiency was observed in every reactor within one month. However, thebehavior of nitrogen removal performance was different in each reactor. The reactor under freshwaterculture condition (FReactor) showed better nitrogen removal performance than the other reactors andachieved 0.35 kgN/m3/d of nitrogen removal rate within 24days after the beginning of operation. On theother hand, maximum-nitrogen removal rates were 0.12 kgN/m3/d and 0.16 kgN/m3/d in the reactors
under average-condition (AReactor) and marine-condition (MReactor), respectively. Result of bacterial
community analysis indicated that only FAB in FReactor and only MAB in MReactor were respectivelydetected. Besides, only MAB was detected in even AReactor contrary to our expectation.