Japanese Journal of Water Treatment Biology
Online ISSN : 1881-0438
Print ISSN : 0910-6758
ISSN-L : 0910-6758
Volume 45, Issue 4
Displaying 1-5 of 5 articles from this issue
ORIGINALS
  • YUSUKE WATANABE, SEN QIAO, XIAOCHEN XU, JIALI YANG, TAKASHI NISHIYAMA, ...
    Article type: ORIGINALS
    2009 Volume 45 Issue 4 Pages 153-163
    Published: 2009
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    Biofringe (BF) carrier material creates swimming motion due to velocity of downflow wastewater, a characteristic of swim-bed technology, and provides a high degree of substrate-biomass contact. In this study, BF fiber material was packed in a plug-flow activated sludge reactor, to investigate its feasibility in improving the sludge settleability and enhancing the pollutant degradation performance of the activated sludge process. High SBOD5, SCOD, and ammonium removal efficiencies of 99.1%, 96.5% and 83.6%, respectively were obtained at volumetric loading rate of 4.5 kg–SCOD/m3/d. SVI values below 50 ml/g and high settling velocities demonstrated satisfactory settling characteristics of the biomass, which were attributed to the increase in the size of the biomass flocs as a result of use of BF carrier material. Relatively low viscosity of mixed liquor also facilitated sludge settling performance as no sludge bulking problems were encountered throughout the experimental period. Existence of a large amount of protozoa and metazoa observed through microscopic examination was considered to contribute to the low sludge yield compared to conventional activated sludge. Microbial analysis demonstrated microbial community shift between the seed sludge and the sludge sample after 378 days of operation with proteobacteria to be predominant. The results demonstrated that use of swim-bed technology enhanced treatment performance and provided process stability to the conventional activated sludge process.
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  • YASUO TANAKA, NOBUTAKA TESHIMA, HIDEAKI SHINOZAKI, ATUSHI YATAGAI, HIR ...
    Article type: ORIGINALS
    2009 Volume 45 Issue 4 Pages 165-175
    Published: 2009
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    In order to remove nitrogen and phosphorus contained in secondary treated swine wastewater, performance of two steps fixed bed reactor process was examined, which consisted of autotrophic denitrification reactor filled with S0-CaCO3-medium (3-5 mm in diameter) and a phosphate absorption reactor filled with autoclaved-light-weight-concrete (ALC)-medium (5-8 mm in diameter). The former medium had coating layer of sulfur-CaCO3 mixture around perlite particle nuclei. The latter medium was byproduct of autoclaved light weight concrete production. Removal rate of NOx-N by the denitrification reactor increased rapidly during initial about 5 days, and maintained over 95% removal rate until about 30 days with NOx-N loading rate of about 1.5 kg/nominal m3・day and nominal HRT of about 9 hours. Consumption of sulfur in the medium was estimated about 2.0 kg for 1 kg nitrogen removal. Phosphate removal rate by ALC medium increased to about 86% during initial 5 days, and this high removal activity continued until about 50 days with nominal HRT of about 9 hours. The phosphate absorbing activity of used ALC medium was recovered by washing in tap water for 5 minutes with stirring. The phosphate removal reactor had also neutralization effect of acidified effluent from denitrification reactor. Both the denitrification reactor and the phosphate removal reactor had some activity of reducing true color of wastewater. Total reduction rate of true color by the two processes was about 30~40%. These results suggest that simple and stable water quality improvement of secondary treated swine wastewater would be possible by combining the two processes.
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  • YUKI KAMIMOTO, KOUJI TSUSHIMA, YOSHIAKI KISO, TOSHIRO YAMADA, YOUNG JU ...
    Article type: ORIGINALS
    2009 Volume 45 Issue 4 Pages 177-184
    Published: 2009
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    N, N-Dimethylformamide (DMF) is ranked as the largest discharged organic material in PRTR (2007). Nitrogen removal is an important subject for biological DMF treatment processes. In this work, the performances of nitrogen removal for DMF, N-methylformamide (MF) and formamide (FA) were examined under acidic conditions with bench-scale mesh-filtration bioreactors, because the mesh filtration was conducted successfully under acidic condition. The reactors were operated at HRT=10 days and at 0.0192 kg-N?(m3?d)–1 of volumetric nitrogen loading rate. The pH was not controlled and, therefore, the mixed liquors in the reactors were kept at around pH=3. The removals of total organic carbon (TOC) were more than 95%, but nitrogen removals were affected by the substrate: Kj-N removals were 95% for DMF and 70% for MF and FA; total nitrogen removals were 55% for DMF, 20% for MF and 10% for FA. In the process fed DMF as a substrate, the production of N2O was observed even under oxic condition. Nitrate reduction was observed even at pH=3, but the nitrate reduction performance decreased rather under neutral pH condition. However, the reduction from N2O to N2 was suppressed under wide range of pH conditions.
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  • HIROFUMI TSUTSUI, SATOSHI SODA, SATOSHI TAKEDA, HIDETAKA OHTSUKI, DAIS ...
    Article type: ORIGINALS
    2009 Volume 45 Issue 4 Pages 185-191
    Published: 2009
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    Conjugation of a self-transmissible, broad-host-range, mercury resistant plasmid pJP4 harbored in Escherichia coli HB101 into activated sludge bacteria was investigated. Filter mating experiments were performed on the nutrient agar plate with E. coli HB101 (pJP4) and the activated sludge bacteria as the donor and the recipients for conjugation, respectively. Transfer frequencies were 2.0×10–1 – 5.8×10–1 per donor and 2.2×10–1 per potential recipient. Most of the transconjugants were inferentially identified as Burkholderia cepacia and Sphingomonas paucimobilis, which are common bacteria in the activated sludge process. Some transconjugants showed higher resistance to HgCl2 (up to 100 mg/l) than the original host of pJP4, Cupriavidus necator JMP134 (50 mg/l).
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NOTE
  • YOSHIMASA AMANO, YUSUKE SAKAI, TAKUMI SEKIYA, XIN QIAN, YOKO FUJIMURA, ...
    Article type: NOTES
    2009 Volume 45 Issue 4 Pages 193-200
    Published: 2009
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    In Lake Teganuma, the shift of dominant species from blue-green algae (Microcystis aeruginosa [M. aeruginosa]) to diatoms (Cyclotella sp.) has been observed since 2000 as a result of the discharge of Tone River water into Lake Teganuma through the North-chiba Water Conveyance Channel. In this study, the influence of phosphorus fluctuation under relatively high silicon concentration, reflecting the condition in Lake Teganuma after 2000, on the shift of dominant species was experimentally examined through individual monoculture and competitive biculture experiments. The results from monoculture experiment showed that the half-saturation constant and uptake rate of phosphorus for M. aeruginosa was respectively lower and faster than that for Cyclotella sp., representing that M. aeruginosa possesses much higher growth potential than Cyclotella sp. under the phosphorus limited condition. The outcome of competitive biculture experiment obviously reflected these results, i.e., dominance of M. aeruginosa with a proportion of 99 % in total cell. Therefore, phosphorus fluctuation under the high silicon concentration could be interpreted as a minor factor for the shift of dominant species, from M. aeruginosa to Cyclotella sp. as observed in Lake Teganuma.
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