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Section Four WASTE TREATMENT PROCESSES D. ANAEROBIC BIOLOGICAL 44 FUNDAMENTAL PRINCIPLES OF THE ANAEROBIC SEQUENCING BATCH REACTOR PROCESS Shihwu Sung, Graduate Research Assistant Richard R. Dague, Professor of Environmental Engineering Department of Civil Engineering Iowa State University Ames, Iowa 50011 INTRODUCTION The first high-rate anaerobic process was developed as a result of studies by Fullen in 1953,' Schroepfer et al. in 1955,2 Steffen in 1958,} and Schroepfer and Ziemke in 1959.4,s The process was analogous to the aerobic activated sludge and was called the "anaerobic contact process". Several other high-rate anaerobic processes have been developed and are being applied throughout the world. These include the anaerobic filter,6"8 the upflow anaerobic sludge blanket,9"" and the fluidized-bed process. Speece listed and described these processes in detail.12 In the 1960s, Dague" conducted laboratory studies on methods of increasing the microbial population in anaerobic reactors. The studies involved batch feeding, internal solids separation, and supernatant wasting. The process was called "anaerobic activated sludge."14 The anaerobic activated sludge process was capable of achieving long solids retention times (SRT) with relatively short hydraulic retention times (HRT) as a result of bioflocculation and efficient solids separation within the reactor. Although not recognized at the time (1966), what is now called "granulation" of the biomass was occurring in the process.13"15 The writers and coworkers at Iowa State University16"18 have been conducting studies on a new anaerobic reactor called the "Anaerobic Sequencing Batch Reactor" (U.S. Patent Pending). The system is analogous to the anaerobic contact process except that biomass separation and liquid clarification occur within the reactor rather than in an external clarifier and no vacuum degasification is required. As will be discussed later, the ASBR offers attractive advantages over continuous-flow, suspended-growth anaerobic processes. The purpose of this paper is to discuss the fundamental principles of the ASBR, present data from laboratory studies aimed at evaluating the performance of the process and lo present a design model based on Monod kinetics for use in sizing the ASBR. PRINCIPLES OF THE ASBR PROCESS Operating Principles The operating principles for the ASBR are simple. As illustrated in Figure 1, the reactor sequences through four steps; settle, decant, feed, and react. During the settle step, mixing is shut off to allow biomass solids separation. The reactor itself acts as the clarifier. The time required for clarification will vary depending on biomass settleability, but typically ranges from 10 minutes to one hour. From an operational standpoint, it is essential that the sludge blanket be below a predetermined decanting elevation and that the blanket not rise due to the accumulation of biogas within the settled biomass. As will be discussed later, the concentration of mixed liquor suspended solids (MLSS) in the reactor is an important variable affecting the settling velocity of the biomass and also the ability to achieve a clear supernatant for discharge as effluent. An important related variable is the specific process loading rate (food to microorganism ratio, F/M). 47th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 4HIIK. Printed in U.S.A. 393
Object Description
Purdue Identification Number | ETRIWC199244 |
Title | Fundamental principles of the anaerobic sequencing batch reactor process |
Author |
Sung, Shihwu Dague, Richard R. |
Date of Original | 1992 |
Conference Title | Proceedings of the 47th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,43678 |
Extent of Original | p. 393-408 |
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 | 2009-12-10 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 393 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | Section Four WASTE TREATMENT PROCESSES D. ANAEROBIC BIOLOGICAL 44 FUNDAMENTAL PRINCIPLES OF THE ANAEROBIC SEQUENCING BATCH REACTOR PROCESS Shihwu Sung, Graduate Research Assistant Richard R. Dague, Professor of Environmental Engineering Department of Civil Engineering Iowa State University Ames, Iowa 50011 INTRODUCTION The first high-rate anaerobic process was developed as a result of studies by Fullen in 1953,' Schroepfer et al. in 1955,2 Steffen in 1958,} and Schroepfer and Ziemke in 1959.4,s The process was analogous to the aerobic activated sludge and was called the "anaerobic contact process". Several other high-rate anaerobic processes have been developed and are being applied throughout the world. These include the anaerobic filter,6"8 the upflow anaerobic sludge blanket,9"" and the fluidized-bed process. Speece listed and described these processes in detail.12 In the 1960s, Dague" conducted laboratory studies on methods of increasing the microbial population in anaerobic reactors. The studies involved batch feeding, internal solids separation, and supernatant wasting. The process was called "anaerobic activated sludge."14 The anaerobic activated sludge process was capable of achieving long solids retention times (SRT) with relatively short hydraulic retention times (HRT) as a result of bioflocculation and efficient solids separation within the reactor. Although not recognized at the time (1966), what is now called "granulation" of the biomass was occurring in the process.13"15 The writers and coworkers at Iowa State University16"18 have been conducting studies on a new anaerobic reactor called the "Anaerobic Sequencing Batch Reactor" (U.S. Patent Pending). The system is analogous to the anaerobic contact process except that biomass separation and liquid clarification occur within the reactor rather than in an external clarifier and no vacuum degasification is required. As will be discussed later, the ASBR offers attractive advantages over continuous-flow, suspended-growth anaerobic processes. The purpose of this paper is to discuss the fundamental principles of the ASBR, present data from laboratory studies aimed at evaluating the performance of the process and lo present a design model based on Monod kinetics for use in sizing the ASBR. PRINCIPLES OF THE ASBR PROCESS Operating Principles The operating principles for the ASBR are simple. As illustrated in Figure 1, the reactor sequences through four steps; settle, decant, feed, and react. During the settle step, mixing is shut off to allow biomass solids separation. The reactor itself acts as the clarifier. The time required for clarification will vary depending on biomass settleability, but typically ranges from 10 minutes to one hour. From an operational standpoint, it is essential that the sludge blanket be below a predetermined decanting elevation and that the blanket not rise due to the accumulation of biogas within the settled biomass. As will be discussed later, the concentration of mixed liquor suspended solids (MLSS) in the reactor is an important variable affecting the settling velocity of the biomass and also the ability to achieve a clear supernatant for discharge as effluent. An important related variable is the specific process loading rate (food to microorganism ratio, F/M). 47th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 4HIIK. Printed in U.S.A. 393 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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