title: Development of a BR-UASB-DHS system for natural rubber processing wastewater treatment.
abstract: Natural rubber processing wastewater contains high concentrations of organic compounds, nitrogen, and other contaminants. In this study, a treatment system composed of a baffled reactor (BR), an upflow anaerobic sludge blanket (UASB) reactor, and a downflow hanging sponge (DHS) reactor was used to treat natural rubber processing wastewater in Vietnam. The BR showed good total suspended solids (TSS) removal of 47.6%, as well as acidification of wastewater. The UASB reactor achieved a high chemical oxygen demand (COD) removal efficiency of 92.7 ± 2.3% and energy recovery in the form of methane with an organic loading rate of 12.2 ± 6.6 kg-COD m-3day-1. The DHS reactor showed high performance in residual organic matter removal from UASB effluent. In total, the system achieved high-level total COD removal of 98.6% ± 1.2% and TSS removal of 98.0% ± 1.4%. Massive parallel 16S rRNA gene sequencing of the retained sludge in the UASB reactor showed the predominant microbial phyla to be Bacteroidetes, Firmicutes, Proteobacteria, WWE1, and Euryarchaeota. Uncultured bacteria belonging to the phylum Bacteroidetes and Phylum WWE1 were predominant in the UASB reactor. This microbial assemblage utilizes the organic compounds contained in natural rubber processing wastewater. In addition, the methane-producing archaea Methanosaeta sp. and Methanolinea sp. were detected.
authors.affiliation: a Department of Environmental Systems Engineering , Nagaoka University of Technology , Nagaoka , Niigata , Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Watari
authors.affiliation: b Department of Biotechnology , Hanoi University of Science and Technology , Hanoi , Vietnam.
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Thanh
authors.affiliation: a Department of Environmental Systems Engineering , Nagaoka University of Technology , Nagaoka , Niigata , Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Tsuruoka
authors.affiliation: c Department of Civil and Environmental Engineering , National Institute of Technology, Kure College , Kure , Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tanikawa
authors.affiliation: a Department of Environmental Systems Engineering , Nagaoka University of Technology , Nagaoka , Niigata , Japan.
authors.forename: Kyohei
authors.initials: K
authors.lastname: Kuroda
authors.affiliation: b Department of Biotechnology , Hanoi University of Science and Technology , Hanoi , Vietnam.
authors.forename: Nguyen Lan
authors.initials: NL
authors.lastname: Huong
authors.affiliation: d Department of Chemical Engineering , Hanoi University of Science and Technology , Hanoi , Vietnam.
authors.forename: Nguyen Minh
authors.initials: NM
authors.lastname: Tan
authors.affiliation: e School for Environmental Science and Technology , Hanoi University of Science and Technology , Hanoi , Vietnam.
authors.forename: Huynh Trung
authors.initials: HT
authors.lastname: Hai
authors.affiliation: a Department of Environmental Systems Engineering , Nagaoka University of Technology , Nagaoka , Niigata , Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Hatamoto
authors.affiliation: f Center for Regional Environmental Research , National Institute for Environmental Studies , Tsukuba , Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Syutsubo
authors.affiliation: g Department of Bioengineering , Nagaoka University of Technology , Nagaoka , Niigata , Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: a Department of Environmental Systems Engineering , Nagaoka University of Technology , Nagaoka , Niigata , Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamaguchi
keywords: Downflow hanging sponge; baffled reactor; microbial community analysis; natural rubber; upflow anaerobic sludge blanket