Japanese Journal of Water Treatment Biology
Online ISSN : 1881-0438
Print ISSN : 0910-6758
ISSN-L : 0910-6758
Volume 44, Issue 1
Displaying 1-6 of 6 articles from this issue
ORIGINALS
  • TSUYOSHI ICHINARI, AKITAKA OHTSUBO, TETSUNORI OZAWA, KOHJI HASEGAWA, K ...
    Article type: ORIGINALS
    2008 Volume 44 Issue 1 Pages 1-9
    Published: 2008
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    In small-scale domestic wastewater treatment facilities (Johkasou), it is an important subject to reduce the excess sludge withdrawn from the system, because many of human excrement treatment plants have insufficient capacity for receiving the sludge. In this study, we focused on the performance of aerobic digestion for raw sludge (RS) stored in an inflow tank of Johkasou and a mixture of RS and garbage (GMS) under continuous aeration (CA) and intermittent aeration (IA) conditions. The volume of the reactor was 10 l and the treatment was conducted at 10 days of hydraulic retention time (HRT). The sludge obtained from the mixed liquor in the reactor was separated one to three-days interval by a centrifugal separator and returned to the reactor, and the supernatant was withdrawn as an effluent. After the operation, RS or GMS was fed into the reactors. The MLSS in the reactors increased gradually until around 150 days of the experimental period and kept stable concentrations after then (total experimental period: 229 days). The average sludge decomposition ratios for RS were 72.8% under CA condition and 67.8% under IA condition. The average sludge decomposition ratios for GMS were lower than those for RS: 64.7% under CA condition and 53.3% under IA condition. In the case of IA condition, both total nitrogen (TN) removals for RS and for GMS were ca. 95%. When RS was treated under CA condition, pH of the effluent decreased to 5.2, but almost complete nitrification was observed.
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  • MD SHAFIQUZZAMAN, IORI MISHIMA, JUN NAKAJIMA
    Article type: ORIGINALS
    2008 Volume 44 Issue 1 Pages 11-20
    Published: 2008
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    Arsenic removal from ground water by iron oxidizer (Leptothrix spp) was investigated in this study. Batch and column studies were conducted with initial 500 μg/l and 5 mg/l of arsenic and iron, respectively. Batch results showed that 60 % and 51 % As(III) was removed during biological and physicochemical Fe(II) oxidation respectively whereas 96 % As(V) was removed in both cases. On the other hand, 50 % removal of As(V) was observed by adsorption on the iron hydroxides that had been produced after 24 hrs mixing, while As(III) was not adsorbed. It seemed that As(III) were oxidized during biological Fe(II) oxidation and iron oxidizing bacteria itself didn’t oxidize As(III) to As(V). Overall As(III) removal efficiency was investigated in a biological sand bed column. Residual arsenic concentrations in the column effluent were always less than 50 μg/l at the flow rate of 7.2 and 3.6 l/d. Phosphorus was also removed very effectively. The sludge analysis showed that the biological iron and arsenic oxidation and their subsequent adsorption were taken place mainly at the top of the column bed. This cost effective technology could be applied to treatment of heavily arsenic and iron contaminated ground water.
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  • MASAFUMI TATEDA, LE DUC TRUNG, HUYNH THI MINH HANG, MICHIHIKO IKE, MAS ...
    Article type: ORIGINALS
    2008 Volume 44 Issue 1 Pages 21-28
    Published: 2008
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    Experiments were performed with sewage sludge using a 600 l in-vessel aerated static pile composting system during a two-year period. Fifteen batch runs were operated to determine the distributions of temperature throughout the composting pile in order to assess the proportion of the pile that were exposed to effective and ineffective temperature conditions during composting. Effects and interactions of several main factors such as aeration and moisture content on the evolutions of the process temperature were investigated. Aeration and heat evaporation led to high rates of moisture removal from the composting pile. Rapid reduction of moisture seemed to result in a significant reduction in biodegradation rate, thereby causing low temperature zones in the composting pile. This study proved that aeration rate and initial moisture content had a great influence on composting performance.
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  • YOSUKE YAMAOKA, KENJI TAKENO, NAPAVARN NOPARATNARAPORN, KEN SASAKI
    Article type: ORIGINALS
    2008 Volume 44 Issue 1 Pages 29-39
    Published: 2008
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    Oil degradation in synthetic sewage wastewater was investigated using a photosynthetic bacterium, Rhodobacter sphaeroides S (S strain). When a pure culture of S strain was prepared with glutamate-malate medium (GM medium) containing a salad oil, about 60 % of the oil was degraded under aerobic-dark conditions at 6 days, while oil degradation was relatively small under anaerobic-light conditions. Lipase hydryzed tri-glycerides to glycerol and fatty acids were observed extracellularly in the aerobic-dark culture. Lipase was produced when the S strain grew up with favorable substrates such as glutamate-malate and glucose in the medium. The lipase activity was quite lower than that of Pseudmonus and Bacillus lipase activities. High cell density enhanced oil degradation rather than lipase production in the liquid. S strain well utilized C12 to C18 fatty acids and glycerol as carbon sources respectively.
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  • YUSUKE JIMBO, KUNIHIRO OKANO, MOTOO UTSUMI, NORIO SUGIURA
    Article type: ORIGINALS
    2008 Volume 44 Issue 1 Pages 41-48
    Published: 2008
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    Toxic Microcystis sp. have been widely recognized as the most common bloom-forming cyanobacteria worldwide. In this study, initial screening method of detection of microcystin-producing Microcystis sp. with simplification, rapidness and sensitiveness was developed, using whole-cell PCR (polymerase chain reaction) and competitive PCR. When whole-cell PCR was carried out on axenic microcystin-producing Microcystis sp., the amplification products were the same size as the products obtained from traditional PCR performed on DNA extracted from Microcystis sp.; and the method was effective in selectively identifying the amplification products from toxic strains. Using the whole-cell method, the target sequence (microcystin synthase gene) could be amplified at least twice as rapidly without DNA extraction, and detection of toxic Microcystis sp. by whole-cell PCR of the target DNA sequence took 1/3 the time required for high-performance liquid chromatography (HPLC) detection of the toxic microcystin. Moreover, the method proved to be sensitive enough to detect toxic cyanobacteria in a sample with less than 10,000 Microcystis cells per ml (about 60 cells per PCR reaction). It was also possible to detect toxic cyanobacteria at in-situ levels as well as in axenic Microcystis strains. Moreover, microcystin-producing Microcystis sp. could be quantified simply by competitive whole-PCR.
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  • NAOSHI FUJIMOTO, YUTA SAKUUCHI, AKIHIRO OHNISHI, MASAHARU SUZUKI, NORI ...
    Article type: NOTES
    2008 Volume 44 Issue 1 Pages 49-55
    Published: 2008
    Released on J-STAGE: March 10, 2018
    JOURNAL FREE ACCESS
    The flagellate protozoan Monas guttula was cultured in a suspension of cyanobacterium Microcystis viridis with or without ceramic granular media and glass beads to clarify the effect of granular media on the growth of M. guttula. The specific growth rate of M. guttula increased with the addition of granular media and glass beads, and M. viridis decreased rapidly. Upon addition of 40 g glass beads to 100 ml of M. viridis suspension, the specific growth rate increased 20-30%; moreover, the maximum density of M. guttula was over three-fold that of cultures lacking glass beads. These results indicate that granular media and glass beads promote the growth of M. guttula.
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