JaLCDOI 10.18926/fest/11439
FullText URL 012_071_076.pdf
Author Chen W.| Yoshida R.| Kawara, Osami|
Abstract The Asahi River Dam reservoir is one of the important fresh water resources in Okayama, Japan, and its eutrophication has been noted since the 1980s. Therefore, aeration has been applied to control the growth of phytoplankton. In this study, we discussed the effect of aeration and water-intake depth on the water quality distribution in the reservoir, based on numerical simulation and observation. The principal conclusions were as follows:(1) The numerical simulation models applied here reproduced observations fairly well. (2) Water intake from the surfacce layer reduced the concentration of chlorophyll a in the surface layers. Water intake from the middle or bottom layer improved the deficit of dissolved oxygen in the bottom layers. (3) Aeration together with water intake from the middle or bottom layer improved the deficit of dissolved oxygen in the bottom layers.
Keywords the Asahi River Dam Reservoir numerical simulation eutrophication water intake depth dissolved oxygen chlorophylla
Publication Title 岡山大学環境理工学部研究報告
Published Date 2007-03-15
Volume volume12
Issue issue1
Start Page 71
End Page 76
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002314056
JaLCDOI 10.18926/fest/11525
Title Alternative A Study on Influence of Current Velocity on Phytoplankton
FullText URL 007_045_053.pdf
Author Li, Jinsong| Kawara, Osami| Ono, Yosiro|
Abstract The main problems caused by eutrophication result from the increase of phytoplankton. Therefore, controlling the increase of phytoplankton is the most important. In this study, we discuss the influence of current velocity on the growth of phytoplankton based on the field experiments and laboratory experiments. The laboratory experiments for the influence of current velocity on the growth have been conducted using circular channels, and the field experiments were conducted using a shallow pond. The results of the experiments show current velocity inhibits the growth of phytoplankton.
Keywords Eutrophication growth of phytoplankton influence of current velocity experiment
Publication Title 岡山大学環境理工学部研究報告
Published Date 2002-03-22
Volume volume7
Issue issue1
Start Page 45
End Page 53
ISSN 1341-9099
language 日本語
File Version publisher
NAID 120002313529
JaLCDOI 10.18926/15420
FullText URL Mem_Fac_Eng_OU_26_1_61.pdf
Author Kawara, Osami| Danno Hideki| Kunimatsu Takao|
Abstract Lake Biwa is the largest lake in Japan, and one of the most important fresh water resources. The Hino River is the fourth largest river among the rivers which flow into Lake Biwa. The eutrophication of the lake has been warned since the 1960s. In order to improve the water quality of the lake, to decrease the loads through rivers is inevitable. Therefore, it is needed to predict the effects of measures to control pollutant loads and the influence of development in the basin on the loads from rivers before developing the basin and taking measures. This paper deals mainly with the model of water quality management for the Hino River and the effects of the development in the basin on the water quality. The model was formulated considering loads from forests, rice paddy fields, households, housing land, industrial factories. Using this model, a calculation system by a microcomputer was developed and the influence of urbanization of the basin was discussed.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1991-11-30
Volume volume26
Issue issue1
Start Page 61
End Page 73
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307182
JaLCDOI 10.18926/15711
FullText URL Mem_Sch_Eng_OU_11_2_37.pdf
Author Kawara Osami|
Abstract In this paper, we compare ozone with chlorine regarding following respects; (1)Disinfection efficiency (2)Oxidation power (3)Effects of secondary effluents treated by ozone or chlorine on aerobic microorganisms. Both ozone and chlorine are powerfull oxidizing agents. However,those are greatly different from each other in effects of treatment. Ozone is superior to chlorine in oxidation of organics, perfection of disinfection and effects on aerobic microorganisms. On the other hand, chlorine is superior in disinfection of Coliform group bacteria. Based on these results,it may be concluded that chlorination will be effective in disinfection of effluents which do not contain so much contaminants. However in case of rather highly cotaminated effluents, ozonation will be suitable.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1977-01-25
Volume volume11
Issue issue2
Start Page 37
End Page 49
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307819
JaLCDOI 10.18926/15747
FullText URL Mem_Sch_Eng_OU_14_1_139.pdf
Author Kawara Osami|
Abstract In this paper, ozonation of organic substances which are found in wastewater is discussed regarding following respects; (1)removal ratios of COD(Cr) and TOC, (2)removal properties, and (3)oxidation products. The main results are summarized as follows. (l)Ozonation quickly removes proteins and amino acids, but mildly polysaccharides and n-saturated carboxylic acids. (2)The initial removal of COD(Cr) or TOC is quite rapid, but, as the reaction continues, it slows down so drasti-cally that one may suspect that it has completed. (3)Starch and albumine are decomposed to the smaller molecular compounds. (4)The COD(Cr) /TOC ratio of each substance which is chosen in this study decreases. This means that ozonation results in the formation of oxygenated fragments of the original molecule-occurs by bond fission or partial oxidation. (5)Proteins are indispensable components in frothing because they are surface active. They are removed by not only oxidation but also foaming, however, the removal by foaming is not so large.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1979-12-01
Volume volume14
Issue issue1
Start Page 139
End Page 150
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307712
JaLCDOI 10.18926/15784
FullText URL Mem_Sch_Eng_OU_15_2_147.pdf
Author Nago Hiroshi| Kawara Osami|
Abstract In this paper, characteristics of hydraulics and water quality in Kojima Bay are discussed based on field observations. The main results obtained are as follows. (1) The variation of flow rate in Kojima Bay has periods for 30 minutes to 2 hours. This characteristic is represented by a two-dimensional numerical simulation fairly well. (2) The local distributions of salinity and suspended solids show increase in the direction to the mouth of Kojima Bay. On the other hand, the distribution of COD(Mn) is nearly uniform in the whole area of the bay. Salinity appears to be influenced by river discharge sensitively but suspended solids does not. (3) The vertical distributions of salinity and suspended solids are similar. There are similar points between the cross-sectional average of water quality and surface water quality. (4) The surface water quality seems to be influenced by the variation of velocity.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1981-03-30
Volume volume15
Issue issue2
Start Page 147
End Page 164
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002308021
JaLCDOI 10.18926/15838
FullText URL Mem_Sch_Eng_OU_21_2_9.pdf
Author Kawara Osami| Nasu Kiyotaka|
Abstract This study dealt with the characteristics of hydrodynamics of Kojima Lake and the influence of a regional sewage treatment system in construction on the lake. Clockwise and anticlockwise circulations are caused by seasonal winds in summer and winter, respectively. The distribution of a conservative material continuously discharged off the shore of the sewage treatment plant is scarcely affected by seasonal winds and river discharges. The sewage treatment system improves the water quality of the lake except T-N.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1987-03-05
Volume volume21
Issue issue2
Start Page 9
End Page 19
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307442
JaLCDOI 10.18926/19585
FullText URL Mem_Fac_Eng_OU_29_1_23.pdf
Author Kawara, Osami| Fukumoto Kohji|
Abstract In this study we investigated the water quality of surface runoff and groundwater runoff from the basins of the Yodo River and the Asahi River based on that separated by a numerical filter. The water quality of the surface runoff is greatly different from the groundwater runoff. The tendency of concentration change in accordance with river discharges is different from each other. The water qtiality of groundwater runoff changes with river discharges clockwise in many cases. The differences of COD and SS originating from those of population and industrial activities in each basin are found in the lower SS concentrations of the surface runoff and the COD cencentrations of the groundwater runoff. The nutrients and chlorine ion were investigated, too.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1994-11-30
Volume volume29
Issue issue1
Start Page 23
End Page 34
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309068
Author Kawara, Osami|
Published Date 2004-11
Publication Title 環境制御
Volume volume26
Content Type Others
Author Kawara, Osami|
Published Date 2003-08
Publication Title 環境制御
Volume volume25
Content Type Others
Author Kawara, Osami|
Published Date 2001-08
Publication Title 環境制御
Volume volume23
Content Type Others
Author Kawara, Osami|
Published Date 2000-09
Publication Title 環境制御
Volume volume22
Content Type Departmental Bulletin Paper
Author Mohri, Shino| Ono, Yoshiro| Kawara, Osami|
Published Date 2000-09
Publication Title 環境制御
Volume volume22
Content Type Departmental Bulletin Paper
Author Kawara, Osami|
Published Date 1997-07
Publication Title 環境制御
Volume volume19
Content Type Others