Journal of Japan Society on Water Environment
Online ISSN : 1881-3690
Print ISSN : 0916-8958
ISSN-L : 0916-8958
Volume 18, Issue 4
Displaying 1-7 of 7 articles from this issue
ORIGINALS
  • Takehiko FUKUSHIMA, Kazuo MATSUSHIGE, R.S.J. WEISBURD
    1995 Volume 18 Issue 4 Pages 279-289
    Published: April 10, 1995
    Released on J-STAGE: January 22, 2008
    JOURNAL FREE ACCESS
    Free water and incubation methods were applied in order to estimate the net rates of primary production, respiration and gas exchange across the air-water interface using continuously measured dissolved oxygen (DO) and pH data for both outdoor ponds and transparent closed and open boxes (20 cm × 20 cm × 20 cm) suspended in the ponds. The rates of primary production and respiration determined with the closed box agreed well with values obtained in parallel incubations by the standard light bottle method. Gas exchange coefficients were calculated by comparison of the differences in the net rates of change of DO and dissolved inorganic carbon between the closed box and the open box. These gas exchange coefficients varied with wind velocities and those for CO2 were about one order of magnitude larger than those for O2 due to chemical enhancement of CO2 gas exchange. Diurnal changes in the stoichiometry of productivity and the effects of temperature on respiration in the open water of the experimental ponds were estimated and discussed.
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  • Hiroko OHASH, Changyuan TANG, Shizuo SHINDO
    1995 Volume 18 Issue 4 Pages 290-296
    Published: April 10, 1995
    Released on J-STAGE: January 22, 2008
    JOURNAL FREE ACCESS
    In natural environment, clay liner has been payed attention to its ability as minimizing the potential for groundwater contamination at waste disposal site. This study describes the distribution of TCE between clays and NaCl solutions in various concentration by column and batch experiments. Clay used were smectite, kaoline and their mixtures. TCE sorption isotherm show that the partition coefficients (Kd) of smectite and smectite-rich clays are approximately 3-8 times larger than those of kaoline and kaoline-rich clays. The present results suggest that clays, especially smectite, may be one of effective natural materials available for liner.
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  • Eijiro TAKASHIMA, Hiroaki TANAKA, Eiichi NAKAMURA
    1995 Volume 18 Issue 4 Pages 297-306
    Published: April 10, 1995
    Released on J-STAGE: January 22, 2008
    JOURNAL FREE ACCESS
    The Ohhori and Ohtsu Rivers are the two major rivers flowing into Lake Teganuma. To gain an understanding of SS, BOD, COD, nitrogen and phosphorus loads flowing into the lake, pollutant loadings were observed at downstream points of the two rivers. According to the runoff characteristics of the observed pollutant loadings, pollutant load could be separated into “dry weather load” and “wet weather load”. The wet weather load is caused by direct runoff of rainfall and could be represented by a regression equation using depth of runoff, antecedent precipitation factor and peak rainfall intensity as independent variables. As a result of annual pollutant load estimation, the ratio of annual wet weather load to annual total (dry+wet) was about 70 percent for SS, about 30 percent for BOD and COD, and 10-20 percent for T-N and T-P. Moreover, the ratios between dissolved and particulate constituents in dry and wet weather loads for COD, T-N and T-P were clarified. Furthermore, the runoff characteristics of constituents of T-N, i.e., nitrite, nitrate and so on, were investigated.
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  • Mitsumasa MURAKAMI, Tadatsugu YOSHIKI, Yoshiki URAKAMI
    1995 Volume 18 Issue 4 Pages 307-314
    Published: April 10, 1995
    Released on J-STAGE: January 22, 2008
    JOURNAL FREE ACCESS
    A system with a submerged biofilter was employed for purifing pond water. The slime on the biofilm has a high ability of adsorption of pollutants when BOD loading is below one tenth of the ordinary. The circulating number, the ratio of the flow rate to the pond volume, is important for total purifing system. The number is 1-2d-1 under the conditions in which the flow of the pond is complete mixing type, the specific growth rate of algae is 0.5-1d-1, and the removal ratio of SS is 0.5.
    The experimental biofilter bed for the pond water of 450m3 was 0.45m width with a depth of 0.6m. The bed packed with the media of 22mm pitch corrugated plates was elongated about 80m to introduce the adsorption ability and to deduce the excess sludge and was not aerated. The result showed that the quality of the pond water maintained BOD 1mg·l-1, SS 0.9mg·l-1, and transparency > 100cm. The removal ratio of SS on the bed was about 60%.
    This is an energy saving system because the filtering head of the bed is lower than that of filters such as a sand filter or a filter cloth.
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  • Chung Hwan KIM, Masaaki HOSOMI, Mitsumasa OKADA, Akihiko MURAKAMI
    1995 Volume 18 Issue 4 Pages 315-323
    Published: April 10, 1995
    Released on J-STAGE: January 22, 2008
    JOURNAL FREE ACCESS
    The effects of clay on the fouling due to algogenic organic matter in the cross-flow ultrafiltration (MWCO 50,000, polysulfone, 100 kPa) were evaluated by algal cells, intercellular organic matter (IOM), extracellular organic matter (EOM) and anaerobic and aerobic decomposition products of algae in the presence of clay. The algae selected in this study were Microcystis aeruginosa, Chlorella pyrenoidosa and Melosira granulate. Algae was taken by plankton nets in Lake Tsukui in order to obtain anaerobic and aerobic decomposition of algae products. The kaolin was used as clay in this study. The flux of dispersions containing algal cells decreased with an increase in the cells number of algae, but increased with coexistence of kaolin. The flux of dispersions containing EOM and microbial decomposition products decreased with the increase of the fraction of organic matter having molecular weight more than molecular weight cut-off (MWCO) of membrane.
    The flux of dispersions containing these organic substances with coexistence of kaolin decreased with the increase of the amount of kaolin, but they had nothing to do with their molecular weight distribution. The flux of dispersions containing IOM was not affected by the coexistence of kaolin.
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  • Kazuhito ARAI, Hiroshi NAGAOKA
    1995 Volume 18 Issue 4 Pages 324-331
    Published: April 10, 1995
    Released on J-STAGE: January 22, 2008
    JOURNAL FREE ACCESS
    Membrane separation was applied to wastewater treatment in an activated sludge process directly submerging hollow fiber membrane modules in an aeration tank. Advantages of the process are ; 1) no suspended solids in treated water, 2) low energy requirement, and 3) compactness in the total system. The objective of this study in to develop optimum form of the membrane module and the operation cycle for the direct-submerging membrane separation activated sludge process. Five different types of end-free hollow fiber modules were prepared and the effect of intermittent operation cycle was investigated. New indexes for the evaluation of membrane modules were proposed.
    The conclusions of this research are as follows :
    1) One-end free hollow fiber membrane modules were quite effective for the direct-submerging membrane separation activated sludge.
    2) The characteristic of filtration was influenced by length and thickness of hollow fiber.
    3) Long and thick fiber membrane module maintained high flux of filtration, while thin this fiber membrane module showed low flux volume, which was caused by the intertwinement of the fibers.
    4) According to evaluation indexes (Permeate flow rate efficiency coefficient and particle volume removal time), short intermittent operation cycle (1min-1min) and long cycle (6hours -6hours) showed almost similar characteristics of filtration.
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NOTE
  • Takehiko FUKUSHIMA, Akio IMAI, Kazuo MATSUSHIGE, Morihiro AIZAKI, Je-c ...
    1995 Volume 18 Issue 4 Pages 332-337
    Published: April 10, 1995
    Released on J-STAGE: January 22, 2008
    JOURNAL FREE ACCESS
    Aquatic dissolved organic matter (DOM) sampled from lakes and rivers was fractionated by Sep-Pack mini-cartridges (PS-2 : polystyrene nonionic resins and tC18 : ODS reverse-phase resins) and the characteristics were discussed with the results of bio-degradability tests. Our experiments showed that trapped organic matter had very low bio-degradability./ The trapped rate increased with incubation time during the degradation tests./ The trapped percentages of DOM were nearly the same as the proportions of refractory DOM in the samples obtained from various waters./ These cartridges could trap more than 70% of fulvic acids extracted from L. Kasumigaura's water. Therefore, we suggest that the trapped rate of DOM by such mini-cartridges gives a useful index of bio-degradability of aquatic DOM.
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