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Methods for Operators of Wastewater Treatment Plants to Determine BOD Parameters OWEN SLETTEN, Public Health Engineer Division of Environmental Engineering Nebraska State Department of Health Lincoln, Nebraska INTRODUCTION The rate of biochemical oxidation of organic matter is a parameter of great interest and importance to the sanitary engineer, and as the writer shall endeavor to prove, also the the operators of the wastewater treatment plant. Streeter and Phelps (1) introduced the concept that the rate of biochemical oxidation is proportional to the concentration of unoxidized substance, measured in terms of oxidizability. This is a first-order reaction, which may be written y = L(l-10"'ct), where y is the BOD at time t, and L corresponds to the theoretical ultimate BOD. Many methods for calculation of BOD parameters have been developed by other investigators, such as Young and Clark, (2) Theriault, (3) Thomas, (4) Fair, (5) Wiegand, (6) Fujimoto, (7) Moore, (8) Sheehy, (9) and Navone (10). This investigator presents procedures which are quite unlike those developed by these scientists but hopefully of practical use even to the wastewater treatment plant operator who is not well grounded in mathematics. The 5-day BOD is a widely-used parameter to assess wastes in water and sewage but it is the contention of the writer that the velocity of it's reaction, commonly termed the "k" parameter, is the really significant element. It is his thesis that routine determination of the k parameter can be effectively used by sewage plant operators as one of the ways of measuring efficiency of treatment of sewage or wastewater. The k parameter is a measure of the rate of progression of the biochemical oxidation. A high k rate is held to mean a rapid rate of waste decomposition. If this idea is valid, the operator should try to achieve a high k rate, since this is an indication of efficient treatment. In short, he should modify or control the operation of the treatment facility to get as high a k rate as possible. THE NATURE OF THE BOD REACTION Ideally, the BOD curve plotted on semilog graph paper, produces a smooth asymptotic line, the lower end of which approaches but never reaches the y-axis at time zero, while the upper end gradually approaches an imaginary line, parallel with the x-axis, which is equivalent to "L", the ultimate BOD. Figure 1 illustrates such an asymptotic curve, where L is equivalent to 100 mg/1, k is 0.12, and Ty2 (half-life) is 2.50 days. Half-life is the length in days, at any time during the BOD progression, required for half of the remaining waste to be oxidized. For example, if a given waste is 50 percent "destroyed" in the biochemical 740
Object Description
Purdue Identification Number | ETRIWC197168 |
Title | Methods for operators of wastewater treatment plants to determine BOD parameters |
Author | Sletten, Owen |
Date of Original | 1971 |
Conference Title | Proceedings of the 26th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,19214 |
Extent of Original | p. 740-752 |
Series | Engineering extension series no. 140 |
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 | 2009-06-25 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 740 |
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 | Methods for Operators of Wastewater Treatment Plants to Determine BOD Parameters OWEN SLETTEN, Public Health Engineer Division of Environmental Engineering Nebraska State Department of Health Lincoln, Nebraska INTRODUCTION The rate of biochemical oxidation of organic matter is a parameter of great interest and importance to the sanitary engineer, and as the writer shall endeavor to prove, also the the operators of the wastewater treatment plant. Streeter and Phelps (1) introduced the concept that the rate of biochemical oxidation is proportional to the concentration of unoxidized substance, measured in terms of oxidizability. This is a first-order reaction, which may be written y = L(l-10"'ct), where y is the BOD at time t, and L corresponds to the theoretical ultimate BOD. Many methods for calculation of BOD parameters have been developed by other investigators, such as Young and Clark, (2) Theriault, (3) Thomas, (4) Fair, (5) Wiegand, (6) Fujimoto, (7) Moore, (8) Sheehy, (9) and Navone (10). This investigator presents procedures which are quite unlike those developed by these scientists but hopefully of practical use even to the wastewater treatment plant operator who is not well grounded in mathematics. The 5-day BOD is a widely-used parameter to assess wastes in water and sewage but it is the contention of the writer that the velocity of it's reaction, commonly termed the "k" parameter, is the really significant element. It is his thesis that routine determination of the k parameter can be effectively used by sewage plant operators as one of the ways of measuring efficiency of treatment of sewage or wastewater. The k parameter is a measure of the rate of progression of the biochemical oxidation. A high k rate is held to mean a rapid rate of waste decomposition. If this idea is valid, the operator should try to achieve a high k rate, since this is an indication of efficient treatment. In short, he should modify or control the operation of the treatment facility to get as high a k rate as possible. THE NATURE OF THE BOD REACTION Ideally, the BOD curve plotted on semilog graph paper, produces a smooth asymptotic line, the lower end of which approaches but never reaches the y-axis at time zero, while the upper end gradually approaches an imaginary line, parallel with the x-axis, which is equivalent to "L", the ultimate BOD. Figure 1 illustrates such an asymptotic curve, where L is equivalent to 100 mg/1, k is 0.12, and Ty2 (half-life) is 2.50 days. Half-life is the length in days, at any time during the BOD progression, required for half of the remaining waste to be oxidized. For example, if a given waste is 50 percent "destroyed" in the biochemical 740 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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