title: A novel open-type biosensor for the in-situ monitoring of biochemical oxygen demand in an aerobic environment.
abstract: Biochemical oxygen demand (BOD) is a widely used index of water-quality assessment. Since bioelectrochemical BOD biosensors require anaerobic conditions for anodic reactions, they are not directly used in aerobic environments such as aeration tanks. Normally, the BOD biosensors are closed-type, where the anode is packed inside a closed chamber to avoid exposure to oxygen. In this study, a novel bioelectrochemical open-type biosensor was designed for in-situ monitoring of BOD during intermittent aeration. The open-type anode, without any protection against exposure to oxygen, was directly inserted into an intermittently aerated tank filled with livestock wastewater. Anodic potential was controlled using a potentiostat. Interestingly, this novel biosensor generated similar levels of current under both aerating and non-aerating conditions, and showed a logarithmic correlation (R2> 0.9) of current with BOD concentrations up to 250 mg/L. Suspended solids in the wastewater attached to and covered the whole anode, presumably leading to the production of anaerobic conditions inside the covered anode via biological oxygen removal. Exoelectrogenic anaerobes (Geobacter spp.) were detected inside the covered anode using the 16S-rRNA gene. This biosensor will have various practical applications, such as the automatic control of aeration intensity and the in-situ monitoring of natural water environments.
authors.affiliation: Division of Animal Environment and Waste Management Research, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), 2 Ikenodai, Tsukuba 305-0901, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: Animal Husbandry Research Institute of the Kumamoto Prefectural Agricultural Research Center, 3801 Sakae, Koshi 861-1113, Japan.
authors.forename: Natsuki
authors.initials: N
authors.lastname: Ookawa
authors.affiliation: Division of Animal Environment and Waste Management Research, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), 2 Ikenodai, Tsukuba 305-0901, Japan.
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Ishida
authors.affiliation: Advanced Genomics Breeding Section, Institute of Crop Science, NARO, 1-2 Owashi, Tsukuba 305-8634, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kanamori
authors.affiliation: Advanced Genomics Breeding Section, Institute of Crop Science, NARO, 1-2 Owashi, Tsukuba 305-8634, Japan.
authors.forename: Harumi
authors.initials: H
authors.lastname: Sasaki
authors.affiliation: Advanced Genomics Breeding Section, Institute of Crop Science, NARO, 1-2 Owashi, Tsukuba 305-8634, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Katayose
authors.affiliation: Division of Animal Environment and Waste Management Research, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization (NARO), 2 Ikenodai, Tsukuba 305-0901, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yokoyama