著者

住友 恒 金子 光美

出版者

Japan Society of Civil Engineers

雑誌

衛生工学研究論文集 (ISSN:09134069)

巻号頁・発行日

vol.19, pp.128-135, 1983 (Released:2010-03-17)

参考文献数

7

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For the purpose of leveling up safty in water supply, the quantification of virus concentration in water resource is required, and one of the most important basic data required for the quantification or the quantitative prediction is the decay constant of viruse in natural water. Therefore, the natural decay or inactivation of Coxsackie-B virus is observed and measured in a cirulative channel (diameter 40cm, width 10cm, depth 20cm) in a laboratory. The experimental conditions are controlled in temperature and sunlight. The former is by a regulative heater and the latter is by a window shutter. The results are summarized in the following forms as κθ=κ20 (1.175) (θ-20), κ20=1.41 (in sunlight condition) and κ'θ=κ'20 (1.143) (θ-20), k'20 =0.87 (in dark condition), where kθ is the decay constant (1/day) in the first order reaction under the temperature θ(°C). The mechanism of the inactivation is also briefly discussed in this paper.

著者

細見 正明 岡田 光正 須藤 隆一

出版者

Japan Society of Civil Engineers

雑誌

衛生工学研究論文集 (ISSN:09134069)

巻号頁・発行日

vol.24, pp.151-166, 1988 (Released:2010-03-17)

参考文献数

30

被引用文献数

1

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An ecological model of Lake Yunoko, a dimictic lake, was developed to obtain quantitative information on the nutrient cycle in Lake Yunoko, particularly the sediment-waterinteractions and to assess various programs for eutrophication control. A multi-component dynamic model for nutrients in the bottom sediment-water system was incorporated into the model, one dimensional water temperature-water quality-ecological model. Good agreement between the model calculations and observed nutrients, chlorophyll-a, and dissolved oxygen concentrations in the water and nutrients concentrations in the bottom sediment was noted. The agreement between the model calculations and the measured nutrient flux from bottom sediment during the summer stagnation period was good. The effectiveness of eutrophication control programson chlorophyll-a concentration in the surface water and dissolved oxygen concentration in the bottom water was assessed using the calibrated model. Sediment dredging decreased nutrient flux from bottom sediment. As a result, chlorophyll-a concentrations in the surface water at autumncirculation period decreased in comparison with those of the control simulation. However, sediment dredging had not an effect on the depression of nutrient release flux after 4 years as compared with the control simulation. The depletion of dissolved oxygen in the bottom water during the summer stagnation period was scarcely restored by dredging only. Artificial circulation increased dissolved oxgen in the bottom water more than 5.2 mg 1-1 throughout the year, whereas chlorophyll-a concentration in the surface water scarcely decreased compared with the control simulation.In the case of 50 percent reduction of external phosphorus loading from the wastewater treatment facility, the annual average chlorophyll-a concentration in the surface water decreased to 79 percentof that of the control simulation for the 4 th year.

著者

鈴木 穣 宮原 茂 竹石 和夫

出版者

Japan Society of Civil Engineers

雑誌

衛生工学研究論文集 (ISSN:09134069)

巻号頁・発行日

vol.27, pp.65-74, 1990-12-20 (Released:2010-03-17)

参考文献数

8

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An oxygen supply method to wastewater using gas permeable film in the form of tube was investigated for the purpose of reducing energy consumption for supplying oxygen. Oxygen transfer rate was measured in the case with or without biofilm, which proved the high rate of oxygen transfer with nitrifying biofilm supplied with ammonium substrate. Simultaneous nitrification and denitrification occurred, when the tube with nitrifying biofilm was applied to the treatment of wastewater, resulting in the high rate of organic matter removal. However, periodic sloughing of denitrifying biofilm which formed on the nitrifying biofilm was needed to keep the oxygen transfer rate high. Energy comsumptiom of the process using this tube was calculated to be less than 40% of that of the activated sluge process.