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An Experimental Study of the Effect of Channel Surface Roughness on the Reaeration Rate Coefficient WILLIE P. ISAACS, Professor PRICHA CHULAVACHANA, Student RAYMOND BOGART, Student Department of Civil Engineering New Mexico State University Las Cruces, New Mexico INTRODUCTION The DO required for the stabilization of organic matter in a natural stream is available from the sources that exist in the river and the waste at the point of discharge; that available by means of reaeration and that produced by the photosynthetic activity of the green plants. Reaeration is usually the most important factor in the supply of DO. Streeter and Phelps considered that atmospheric reaeration was the only source of oxygen for many polluted rivers; and that the only withdrawal was by micro-organism's exertion of BOD. They proposed the "Sag Equation" as follows: klLa -kit *->* -M V = ~=- [10 1 -10 l ] +D 10 l k2-kj Where k2 is the reaeration coefficient to the logarithm base ten, k i is the BOD rate constant, , La is the ultimate first stage BOD, and Da is the oxygen deficit at time zero. The values of La and Da may be measured but ki and k2 are difficult to estimate. The value of k i is a characteristic of the waste and is usually assumed to be equal to the BOD rate constant exerted under laboratory conditions. However, k2 is a function of conditions in the receiving water. A simple and reliable method of estimating k2 under all conditions does not presently exist, its development being hindered by a lack of understanding of the true mechanism of the kinetics of gas transfer into water. In 1967, Isaacs (1), using his unique experimental apparatus as an idealized simulated stream, found the reaeration rate constant, k2, to be directly proportional to average stream velocity, and inversely proportional to the average stream depth raised to the 3/2 power. The equation for defining this model is as follows: D 1'2 Um k2-0-06339(9T7vr6li^ in which, Dm is the molecular diffusivity of oxygen into water, 3 is the kinetic viscosity of water, V is the average stream velocity, H is the mean depth of flow, and g is the gravitational constant. Atmospheric reaeration was defined by this equation over a wide range of steady uniform flow conditions in a channel of rectangular cross-section. A single -1464-
Object Description
Purdue Identification Number | ETRIWC1969101 |
Title | Experimental study of the effect of channel surface roughness on the reaeration rate coefficient |
Author |
Isaacs, W. P. (Willie P.) Chulavachana, Pricha Bogart, Raymond |
Date of Original | 1969 |
Conference Title | Proceedings of the 24th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,16392 |
Extent of Original | p. 1464-1476 |
Series | Engineering extension series no. 135 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-05-21 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 1464 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | An Experimental Study of the Effect of Channel Surface Roughness on the Reaeration Rate Coefficient WILLIE P. ISAACS, Professor PRICHA CHULAVACHANA, Student RAYMOND BOGART, Student Department of Civil Engineering New Mexico State University Las Cruces, New Mexico INTRODUCTION The DO required for the stabilization of organic matter in a natural stream is available from the sources that exist in the river and the waste at the point of discharge; that available by means of reaeration and that produced by the photosynthetic activity of the green plants. Reaeration is usually the most important factor in the supply of DO. Streeter and Phelps considered that atmospheric reaeration was the only source of oxygen for many polluted rivers; and that the only withdrawal was by micro-organism's exertion of BOD. They proposed the "Sag Equation" as follows: klLa -kit *->* -M V = ~=- [10 1 -10 l ] +D 10 l k2-kj Where k2 is the reaeration coefficient to the logarithm base ten, k i is the BOD rate constant, , La is the ultimate first stage BOD, and Da is the oxygen deficit at time zero. The values of La and Da may be measured but ki and k2 are difficult to estimate. The value of k i is a characteristic of the waste and is usually assumed to be equal to the BOD rate constant exerted under laboratory conditions. However, k2 is a function of conditions in the receiving water. A simple and reliable method of estimating k2 under all conditions does not presently exist, its development being hindered by a lack of understanding of the true mechanism of the kinetics of gas transfer into water. In 1967, Isaacs (1), using his unique experimental apparatus as an idealized simulated stream, found the reaeration rate constant, k2, to be directly proportional to average stream velocity, and inversely proportional to the average stream depth raised to the 3/2 power. The equation for defining this model is as follows: D 1'2 Um k2-0-06339(9T7vr6li^ in which, Dm is the molecular diffusivity of oxygen into water, 3 is the kinetic viscosity of water, V is the average stream velocity, H is the mean depth of flow, and g is the gravitational constant. Atmospheric reaeration was defined by this equation over a wide range of steady uniform flow conditions in a channel of rectangular cross-section. A single -1464- |
Resolution | 300 ppi |
Color Depth | 8 bit |
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