Japanese Journal of Water Treatment Biology
Online ISSN : 1881-0438
Print ISSN : 0910-6758
ISSN-L : 0910-6758
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Volume 51, Issue 3
Displaying 1-3 of 3 articles from this issue
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ORIGINALS
  • Removal Mechanism of Organic Matter in Conventional Activated Sludge Process
    KAZUHISA MIMURA, HIROSHI DEGUCHI, MINGXING LIU
    Article type: ORIGINALS
    2015 Volume 51 Issue 3 Pages 49-59
    Published: 2015
    Released on J-STAGE: March 10, 2018
    DOIhttps://doi.org/10.2521/jswtb.51.49
    JOURNAL FREE ACCESS
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    The removal mechanism of organic matter in conventional activated sludge process was made clear by deep investigation upon oxygen consumption of organic matter and OUR of activated sludge. It was found that the removal of organic matter in 8 hours was due to the shift of organic matter from liquid phase into sludge （floc）. This explanation was based on following two findings. One was that the period for organic matter being aerobically decomposed was almost the same 10 days as the period to expected endogenous respiration of activated sludge. Another was that the colony count of heterotrophic bacteria in sewage was almost the same order of 107/ml as in activated sludge.The behaviour of organic matter in sludge was able to be described by the characteristic of its oxygen consumption. Then, it was demonstrated that organic matter into aeration tank was almost the same amount as the shifted and accumulated one in activated sludge by this description. Moreover, it was expected that the accumulated organic matter in activated sludge had become easy to be bio-decomposed.
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  • Greenhouse Gases Control and Water Purification Performance in a Johkasou System under Energy Saving Operation
    YUZURU KIMOCHI, KOJI JONO, HIROSHI YAMAZAKI, KAIQIN XU, YUHEI INAMORI
    Article type: ORIGINALS
    2015 Volume 51 Issue 3 Pages 61-68
    Published: 2015
    Released on J-STAGE: March 10, 2018
    DOIhttps://doi.org/10.2521/jswtb.51.61
    JOURNAL FREE ACCESS
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    Greenhouse Gases (GHGs) control and water treatment performance in a Johkasou system with energy saving operation were examined. Bench-scale Johkasou equipments consisted of one anaerobic and four oxic tanks were set up in a thermostatic room at 20 ℃. Following results were obtained: DO concentration could be maintained even in cutting off the aeration (operation) to 1/2 with shorter on/off cycle as 2－hr on / 2－hr off. It was also found that, under such operational condition, there was almost no bad influence of “operation off” on nitrogen and BOD removal. Moreover, on/off operation with shorter cycle could reduce the emission rates of N2O and CH4 greatly as compared with those of the continuous operation. From these results, total GHGs emission calculated for CO2 conversion values with shorter on/off cycle operation achieved below 20% of that of the continuous operation. Although more researches will be needed in order to apply these results to pilot-scale or full-scale wastewater treatment, especially from the viewpoint of water temperature and so on, some possibilities of keeping up with good water treatment performance and control of GHGs with energy saving operation have been achieved.
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NOTES
  • Degradation of formaldehyde by Aspergillus oryzae
    ATSUSHI MINEMURA, RYUICHI KITAMURA, MOTOAKI SANO, SATOSHI OSAWA
    Article type: NOTES
    2015 Volume 51 Issue 3 Pages 69-73
    Published: 2015
    Released on J-STAGE: March 10, 2018
    DOIhttps://doi.org/10.2521/jswtb.51.69
    JOURNAL FREE ACCESS
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    We examined the capacity of Aspergillus oryzae, which is used in the production of traditional fermented foods, to degrade formaldehyde under various conditions. Degradation of formaldehyde was performed using A. oryzae mycelia, which were produced from spore suspensions containing 1.0 × 106 spores ml－1. A. oryzae actively degraded formaldehyde when cultivated in Czapek-Dox (CD) medium containing 50 and 100 mg l－1 formaldehyde, however, formaldehyde degradation was not sustained after an initial decrease in CD medium containing 200 and 300 mg l－1 formaldehyde. In CD medium containing 100 mg l－1 formaldehyde, A. oryzae degraded 89% and 100% of formaldehyde within 24 and 48 h, respectively. In addition, A. oryzae was able to repeatedly degrade formaldehyde added to culture medium at 100 mg l－1. Taken together, these findings suggest that A. oryzae mycelia have a high capacity for the degradation of formaldehyde in liquid samples.
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