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A Laboratory Study of Mixing Conditions in Small Aeration Vessels W. F. MILBURY, Graduate Student W. O. PIPES, Associate Professor of Engineering The Technological Institute Northwestern University Evanston, Illinois R. B. GRIEVES, Assistant Professor of Civil Engineering Illinois Institute of Technology Chicago, Illinois INTRODUCTION Since its inception, the activated sludge process has drawn the attention of investigators who were interested in understanding the mechanisms by which the process operated. In recent years there have been several attempts to describe and evaluate the mixing regime which exists in the aeration portion of the system. The quantitation of the time distribution of oxidizable substrate and "active" suspended solids in the system will contribute significantly to the definition and understanding of the efficiency of this waste treatment process. Last year we presented a paper introducing a mathmetical model describing the effect of the hydraulic regime upon the activated sludge process (1). This model combined equations describing the mixing pattern and biological growth kinetics to produce overall system performance equations. In that paper eight different mixing configurations were considered involving combinations such as complete mixing, plug flow, short-circuiting, stagnant zones, and recycle. In this paper some laboratory studies of mixing conditions in small aeration vessels conducted for experimental verification of this mixing model are reported. Because our biological studies of this model are still in progress, only verification of the hydraulic portion of the mixing model is presented. First a brief review of the hydraulic model is presented, then the experimental methods and equipment are discussed, and finally the experimental results verifying the model are reported and commented upon. HYDRAULIC MODEL The mixing regime is described in this hydraulic model by a volume apportionment method which theoretically divides the aeration tank into several volumes with different mixing patterns. Cholette and Cloutier (2) have presented relationships which consider an "effective" volume of complete mixing, stagnant zone, and short-circuit and plug flow. The actual quantitation of a continuous flow system by this method of hydraulic description is performed by creating a step-change in concentration of some inert component of the feed. Then the change in concentration of this substance in the effluent is observed with time. The nature of the effluent response curve can then be used to characterize the degree of mixing in the system according to this method of hydraulic analysis. The theoretical results which would be obtained from a tracer analysis performed by this method are presented in Figure 1. The vessel of volume, v, initially has a uniform tracer concentration, c0, the same as that of the feed, 927
Object Description
Purdue Identification Number | ETRIWC196471 |
Title | Laboratory study of mixing conditions in small aeration vessels |
Author |
Milbury, W. F. Pipes, Wesley O. Grieves, R. B., 1935- |
Date of Original | 1964 |
Conference Title | Proceedings of the nineteenth Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,11114 |
Extent of Original | p. 927-939 |
Series |
Engineering extension series no. 117 Engineering bulletin v. 49, no. 1(a)-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 | 2009-05-19 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 927 |
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 | A Laboratory Study of Mixing Conditions in Small Aeration Vessels W. F. MILBURY, Graduate Student W. O. PIPES, Associate Professor of Engineering The Technological Institute Northwestern University Evanston, Illinois R. B. GRIEVES, Assistant Professor of Civil Engineering Illinois Institute of Technology Chicago, Illinois INTRODUCTION Since its inception, the activated sludge process has drawn the attention of investigators who were interested in understanding the mechanisms by which the process operated. In recent years there have been several attempts to describe and evaluate the mixing regime which exists in the aeration portion of the system. The quantitation of the time distribution of oxidizable substrate and "active" suspended solids in the system will contribute significantly to the definition and understanding of the efficiency of this waste treatment process. Last year we presented a paper introducing a mathmetical model describing the effect of the hydraulic regime upon the activated sludge process (1). This model combined equations describing the mixing pattern and biological growth kinetics to produce overall system performance equations. In that paper eight different mixing configurations were considered involving combinations such as complete mixing, plug flow, short-circuiting, stagnant zones, and recycle. In this paper some laboratory studies of mixing conditions in small aeration vessels conducted for experimental verification of this mixing model are reported. Because our biological studies of this model are still in progress, only verification of the hydraulic portion of the mixing model is presented. First a brief review of the hydraulic model is presented, then the experimental methods and equipment are discussed, and finally the experimental results verifying the model are reported and commented upon. HYDRAULIC MODEL The mixing regime is described in this hydraulic model by a volume apportionment method which theoretically divides the aeration tank into several volumes with different mixing patterns. Cholette and Cloutier (2) have presented relationships which consider an "effective" volume of complete mixing, stagnant zone, and short-circuit and plug flow. The actual quantitation of a continuous flow system by this method of hydraulic description is performed by creating a step-change in concentration of some inert component of the feed. Then the change in concentration of this substance in the effluent is observed with time. The nature of the effluent response curve can then be used to characterize the degree of mixing in the system according to this method of hydraulic analysis. The theoretical results which would be obtained from a tracer analysis performed by this method are presented in Figure 1. The vessel of volume, v, initially has a uniform tracer concentration, c0, the same as that of the feed, 927 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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