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Model of the Completely-Mixed Activated Sludge Process TOM D. REYNOLDS, Assistant Professor Civil Engineering Department Texas A & M University College Station, Texas f. T. YANG, Graduate Research Assistant Civil Engineering Department University of Texas Austin, Texas INTRODUCTION The purpose of this research was to develop a mathematical model for the complete-mixed activated sludge process with recycle and separate sludge wastage and to develop methods for determining the required design parameters. The scope included mathematical analyses, the testing of a simulated industrial waste in the laboratory for the design parameters and an application of the parameters to hypothetical design problems. The activated sludge process has been used for many years for the treatment of domestic and industrial wastes. The original system, the conventional activated sludge process, has undergone several modifications to overcome operational difficulties and give better and more economical treatments. Some of these modifications are the tapered aeration, step aeration, biosorptionand completely- mixed processes. The completely-mixed process has been largely confined to tne industrial waste treatment plants and small domestic treatment plants, although in recent years it has been increasingly popular as a moderate to large size domestic waste treatment facility. The completely-mixed activated sludge system has many advantages over the other modifications of the activated sludge process. Some of these inherent advantages are: 1) maximum equalization of the Oo uptake rate: 2) maximum damping of shock loads applied to the plant; 3) maximum neutralization of C02 produced during respiration; 4) reduction in the toxicity of a toxic material when the toxic material is biodegradable and is present in low concentrations; and 5) provision of relatively constant environmental conditions for the biological mass. The completely-mixed process gives the optimum environmental conditions for microbial action and gives a greater flexibility in operation than the other activated sludge processes. Because of the previously mentioned advantages it is ideally suited for the treatment of industrial wastes. Wastes high in oxygen demand may be effectively treated since the oxygen uptake rate is uniformly distributed throughout the aeration tank. The other activated sludge processes have high oxygen requirements at the point where the waste enters the aeration tank and thus it may prove difficult to furnish air in sufficient quantities required for stabilizations. Also, in the completely-mixed system a shock load isimmediately mixed with the aeration tank contents and distributed throughout the aeration tank thus its toxicity is minimized. Flow diagrams of the three types of completely-mixed system are shown in - 696 -
Object Description
Purdue Identification Number | ETRIWC196658 |
Title | Model of the completely-mixed activated sludge process |
Author |
Reynolds, Tom D. Yang, J. T. |
Date of Original | 1966 |
Conference Title | Proceedings of the 21st Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,12965 |
Extent of Original | p. 696-713 |
Series |
Engineering extension series no. 121 Engineering bulletin v. 50, no. 2 |
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 | 2009-05-20 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 696 |
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 | Model of the Completely-Mixed Activated Sludge Process TOM D. REYNOLDS, Assistant Professor Civil Engineering Department Texas A & M University College Station, Texas f. T. YANG, Graduate Research Assistant Civil Engineering Department University of Texas Austin, Texas INTRODUCTION The purpose of this research was to develop a mathematical model for the complete-mixed activated sludge process with recycle and separate sludge wastage and to develop methods for determining the required design parameters. The scope included mathematical analyses, the testing of a simulated industrial waste in the laboratory for the design parameters and an application of the parameters to hypothetical design problems. The activated sludge process has been used for many years for the treatment of domestic and industrial wastes. The original system, the conventional activated sludge process, has undergone several modifications to overcome operational difficulties and give better and more economical treatments. Some of these modifications are the tapered aeration, step aeration, biosorptionand completely- mixed processes. The completely-mixed process has been largely confined to tne industrial waste treatment plants and small domestic treatment plants, although in recent years it has been increasingly popular as a moderate to large size domestic waste treatment facility. The completely-mixed activated sludge system has many advantages over the other modifications of the activated sludge process. Some of these inherent advantages are: 1) maximum equalization of the Oo uptake rate: 2) maximum damping of shock loads applied to the plant; 3) maximum neutralization of C02 produced during respiration; 4) reduction in the toxicity of a toxic material when the toxic material is biodegradable and is present in low concentrations; and 5) provision of relatively constant environmental conditions for the biological mass. The completely-mixed process gives the optimum environmental conditions for microbial action and gives a greater flexibility in operation than the other activated sludge processes. Because of the previously mentioned advantages it is ideally suited for the treatment of industrial wastes. Wastes high in oxygen demand may be effectively treated since the oxygen uptake rate is uniformly distributed throughout the aeration tank. The other activated sludge processes have high oxygen requirements at the point where the waste enters the aeration tank and thus it may prove difficult to furnish air in sufficient quantities required for stabilizations. Also, in the completely-mixed system a shock load isimmediately mixed with the aeration tank contents and distributed throughout the aeration tank thus its toxicity is minimized. Flow diagrams of the three types of completely-mixed system are shown in - 696 - |
Resolution | 300 ppi |
Color Depth | 8 bit |
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