Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Continuous flow and batch experiments were carried out under mesophilic conditions (35 degrees C) to determine the effects of gradual increases in cation concentrations on specific methane producing activity (MPA) and microbial community structure in an upflow anaerobic sludge blanket (UASB) reactor fed with molasses wastewater for 300 days. The cation inhibition assay based on MPA as a function of potassium concentration was performed using the retained sludge. The 50% inhibitory concentration for potassium was 600 mM for H-2/CO2 substrate, 300 mM for acetate, and 280 mM for propionate, and inhibition levels were clearly proportional to potassium concentration. The tolerance of retained sludge to potassium inhibition was not clearly changed from low to high saline conditions (day 59, 111, and 201). The 16S rRNA gene sequencing analysis revealed that Methanobacterium and Methanosaeta were the dominant archaea, and the archaeal community was not obviously changed at the genus level during operation. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cej.2017.05.081

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Other Link： http://orcid.org/0000-0001-5426-814X

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN  

In this study, we performed a comprehensive analysis of microbial community compositions in leachate and leachate treatment system (14 processes) during dry and rainy seasons (from February to September and from October to January, respectively), at Khanh Son landfill site, Danang City, Vietnam. In this study, raw leachate in dry and rainy seasons was predominated by Arcobacter, Clostridia, Thermotogales, Methanobacteriaceae, and Methanosaeta. During the two seasons, the system had different microbial community compositions. Orders Methanobacteriales, Clostridiales, MBA08 (order-level clone cluster), and Thermotogales predominated the influent, anaerobic pond, and anoxic pond during the dry season, while Campylobacterales and Pseudomonadales orders were predominant in the anaerobic/anoxic systems during the rainy season. In the facultative pond, aerated ponds, sediment tanks, and polishing ponds, predominant orders during the dry season included Actinomycetales, "Saprospirales", Flavobacteriales, Rhizobiales, Rhodospirillales, Burkholderiales, and Alteromonadales; during the rainy season: Sphingobacteriales, Ricicettsiales, Sphingomonadales, and Pseudomonadales. In the final post treatment (polishing ponds with vegetation), significant removal of organic matter, total nitrogen, and colour occurred, while nitrogen-fixing and root-associated or related organisms predominated. This suggested that the vegetation in the ponds was essential to achieve the sufficient leachate treatment. (C) 2016, The Society for Biotechnology, Japan. All rights reserved.

DOI： 10.1016/j.jbiosc.2016.06.003

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Other Link： http://orcid.org/0000-0001-5426-814X

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC MICROBIOLOGY  

Ammonia oxidation regulates the balance of reduced and oxidized nitrogen pools in nature. Although ammonia-oxidizing archaea have been recently recognized to often outnumber ammonia-oxidizing bacteria in various environments, the contribution of ammonia-oxidizing archaea is still uncertain due to difficulties in the in situ quantification of ammonia oxidation activity. Nitrogen and oxygen isotope ratios of nitrite (delta N-15(NO2-) and delta O-18(NO2-), respectively) are geochemical tracers for evaluating the sources and the in situ rate of nitrite turnover determined from the activities of nitrification and denitrification; however, the isotope ratios of nitrite from archaeal ammonia oxidation have been characterized only for a few marine species. We first report the isotope effects of ammonia oxidation at 70 degrees C by thermophilic Thaumarchaeota populations composed almost entirely of "Candidatus Nitrosocaldus." The nitrogen isotope effect of ammonia oxidation varied with ambient pH (25 parts per thousand to 32 parts per thousand) and strongly suggests the oxidation of ammonia, not ammonium. The delta O-18 value of nitrite produced from ammonia oxidation varied with the delta O-18 value of water in the medium but was lower than the isotopic equilibrium value in water. Because experiments have shown that the half-life of abiotic oxygen isotope exchange between nitrite and water is longer than 33 h at 70 degrees C and pH >= 6.6, the rate of ammonia oxidation by thermophilic Thaumarchaeota could be estimated using delta O-18(NO2-) in geothermal environments, where the biological nitrite turnover is likely faster than 33 h. This study extended the range of application of nitrite isotopes as a geochemical clock of the ammonia oxidation activity to high-temperature environments.
IMPORTANCE
Because ammonia oxidation is generally the rate-limiting step in nitrification that regulates the balance of reduced and oxidized nitrogen pools in nature, it is important to understand the biological and environmental factors underlying the regulation of the rate of ammonia oxidation. The discovery of ammonia-oxidizing archaea (AOA) in marine and terrestrial environments has transformed the concept that ammonia oxidation is operated only by bacterial species, suggesting that AOA play a significant role in the global nitrogen cycle. However, the archaeal contribution to ammonia oxidation in the global biosphere is not yet completely understood. This study successfully identified key factors controlling nitrogen and oxygen isotopic ratios of nitrite produced from thermophilic Thaumarchaeota and elucidated the applicability and its limit of nitrite isotopes as a geochemical clock of ammonia oxidation rate in nature. Oxygen isotope analysis in this study also provided new biochemical information on archaeal ammonia oxidation.

DOI： 10.1128/AEM.00250-16

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Other Link： http://orcid.org/0000-0001-5426-814X

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Molasses wastewater contains high levels of organic compounds, cations, and anions, causing operational problems for anaerobic biological treatment. To establish a high organic loading treatment system for industrial molasses wastewater, this study designed a combined system comprising an acidification tank, a thermophilic multi-stage (MS)-upflow anaerobic sludge blanket (UASB) reactor, mesophilic UASB reactor, and down-flow hanging sponge reactor. The average total chemical oxygen demand (COD) and biochemical oxygen demand removal rates were 85% +/- 3% and 95% +/- 2%, respectively, at an organic loading rate of 42 kgCOD(cr) m(-3) d(-1) in the MS-UASB reactor. By installation of the acidification tank, the MS- UASB reactor achieved low H-2-partial pressure. The abundance of syntrophs such as fatty acid-degrading bacteria increased in the MS- UASB and 2nd-UASB reactors. Thus, the acidification tank contributed to maintaining a favorable environment for syntrophic associations. This study provides new information regarding microbial community composition in a molasses wastewater treatment system. (C) 2015 Published by Elsevier Ltd.

DOI： 10.1016/j.biortech.2015.07.070

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Microbial systems are widely used to treat different types of wastewater from domestic, agricultural, and industrial sources. Community composition is an important factor in determining the successful performance of microbial treatment systems; however, a variety of uncultured and unknown lineages exist in sludge that requires identification and characterization. The present study examined the archaeal community composition in methanogenic, denitrifying, and nitrogen-/phosphate-removing wastewater treatment sludge by Archaea-specific 16S rRNA gene sequencing analysis using Illumina sequencing technology. Phylotypes belonging to Euryarchaeota, including methanogens, were most abundant in all samples except for nitrogen-/phosphate-removing wastewater treatment sludge. High levels of Deep Sea Hydrothermal Vent Group 6 (DHVEG-6), WSA2, Terrestrial Miscellaneous Euryarchaeotal Group, and Miscellaneous Crenarchaeotic Group were also detected. Interestingly, DHVEG-6 was dominant in nitrogen-/phosphate-removing wastewater treatment sludge, indicating that unclear lineages of Archaea still exist in the anaerobic wastewater treatment sludges. These results reveal a previously unknown diversity of Archaea in sludge that can potentially be exploited for the development of more efficient wastewater treatment strategies.

DOI： 10.1007/s00248-014-0525-z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IWA PUBLISHING  

The anaerobic-anoxic sequence batch reactor (A(2)SBR) was applied to achieve nitrogen and phosphorus removal in an energy-saving sewage treatment system involving an up-flow anaerobic sludge blanket combined with a down-flow hanging sponge reactor to treat municipal sewage. After sludge acclimation, the A(2)SBR showed satisfactory denitrification and phosphorus removal performance with total phosphate and nitrate concentrations of the effluent of 8.4 +/- 3.4 mg-N L-1 and 0.9 +/- 0.6 mg-P L-1, respectively. 16S rRNA gene sequence and fluorescence in situ hybridization analyses revealed that 'Candidatus Accumulibacter phosphatis' was the dominant phosphate-accumulating micro-organism. Although a competitive bacterium for polyphosphate-accumulating organisms, 'Ca. Competibacter phosphatis', was not detected, Dechloromonas spp. were abundant. The ppk1 gene sequence analysis showed that the type II lineage of 'Ca. Accumulibacter' was dominant. The results suggest that denitrification and phosphorus removal in the A(2)SBR could be achieved by cooperative activity of 'Ca. Accumulibacter' and nitrate-reducing bacteria.

DOI： 10.2166/wst.2015.016

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Other Link： http://orcid.org/0000-0001-5426-814X

Language：Japanese   Publisher：Japan Society of Civil Engineers  

 We investigated performance of the combined system consisted of a thermophilic (55°C) multi-staged upflow anaerobic sludge blanket (MS-UASB) reactor and a mesophilic (35-40°C) UASB reactor for a high strength molasses wastewater treatment. In MS-UASB reactor at OLR of 42 kgCOD_cr·m^-3·d^-1, the average removal rates of COD_cr and BOD as the combined system were archived up to 82% and 90%, respectively. By microbial community analysis, high levels of genera Thermacetogenium and Methanothermobacter were observed in the granular sludges retained on MS-UASB reactor. It indicates that electron flow for methane production was depended on the way combined acetate oxidizing hydrogen production and hydrogen utilizing methane production.

DOI： 10.2208/jscejer.70.III_151

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Event date： 2021.3

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Event date： 2015.8.1

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Event date： 2014.11

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Language：English   Presentation type：Oral presentation (invited, special)  

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