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30 REDUCTIVE DECHLORINATION OF PERCHLOROETHYLENE (PCE) USING ANAEROBIC SEQUENCING BATCH BIOFILM REACTORS (AnSBBR) Patrick J. Hirl, Graduate Research Assistant Robert L. Irvine, Professor Department of Civil Engineering and Geological Sciences University of Notre Dame Notre Dame, Indiana 46556 INTRODUCTION The Sequencing Batch Reactor (SBR) is a periodically operated, nonsteady state, biological reactor which has been used successfully for the treatment of municipal, industrial, and hazardous waste. The SBR is unique from other nonsteady state biological reactors in that it has discrete fill, react, and decant periods. During the past two years, an Anaerobic Sequencing Batch Biofilm Reactor (AnSBBR) was used to select for, enrich, and modify the physiological state of a microbial consortium in order to promote the dechlorination of PCE to ethylene. The AnSBBR, fed acetate as an electron donor, dechlorinated 6.1 mg (37 pmoles) of PCE to cis- 1,2- dichloroethylene (cDCE) on a daily basis. When the daily PCE added to the reactor was increased to 80 mg (480 pmoles), the reactor produced vinyl chloride (VC) and ethylene. When the daily PCE added to the reactor was reduced to 10 mg (63 pmoles), the reactor maintained the ability to produce ethylene for approximately one month. BACKGROUND Periodic Processes for Wastewater Treatment The SBR is an activated sludge-like, periodic process that has been used effectively for the treatment of both domestic and industrial wastewaters.1-2 Reactor based periodic systems consist of one or more identically operated tanks that provide for the time sequencing of two or more processes or operations (e.g., equalization, biological conversions, and clarification) during a complete reactor cycle. Each cycle may include up to five periods: FILL, REACT, SETTLE, DRAW, and IDLE. During FILL, wastewater enters a partially-full tank containing acclimated biomass. Aerobic or anaerobic reactions can be initiated during FILL by providing either aeration or mixing. After the tank reaches its predetermined maximum liquid level, the flow is either stopped or diverted to another tank by means of a control system. The reactions initiated during FILL are continued during REACT. The time set aside for REACT must be sufficient to allow the desired effluent requirements to be met. After REACT, the biomass is allowed to SETTLE quiescently for a predetermined period of time by shutting down the mixing and aeration equipment. The treated, clarified effluent is then removed during DRAW. This tank now waits during IDLE for the liquid in the other tank to reach its maximum level so that it can begin a new cycle. As can be seen from the above description, the SBR mimics a conventional continuous flow system's treatment train by providing for piecewise equalization (during FILL), biotreatment, and sedimentation in the same tank at different times. In fact, the time set aside for each period in the SBR can be directly related to some corresponding detention time in a conventional continuous flow system (CFS). As a result, it is both appropriate and useful to equate the fraction of the time dedicated to a particular period with the fraction of the total SBR system volume that has been set aside for that period. Clearly, then, if the time (i.e., volume) allowed for one period 51st Purdue Industrial Waste Conference Proceedings, 1996, Ann Arbor Press, Inc., Chelsea. Michigan 48118. Printed in U.S.A. 289
Object Description
Purdue Identification Number | ETRIWC199630 |
Title | Reductive dechlorination of perchloroethylene (PCE) using anaerobic sequencing batch biofilm reactors (AnSBBR) |
Author |
Hirl, Patrick J. Irvine, Robert L. |
Date of Original | 1996 |
Conference Title | Proceedings of the 51st Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,46351 |
Extent of Original | p. 289-296 |
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 | 2009-10-27 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 289 |
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 | 30 REDUCTIVE DECHLORINATION OF PERCHLOROETHYLENE (PCE) USING ANAEROBIC SEQUENCING BATCH BIOFILM REACTORS (AnSBBR) Patrick J. Hirl, Graduate Research Assistant Robert L. Irvine, Professor Department of Civil Engineering and Geological Sciences University of Notre Dame Notre Dame, Indiana 46556 INTRODUCTION The Sequencing Batch Reactor (SBR) is a periodically operated, nonsteady state, biological reactor which has been used successfully for the treatment of municipal, industrial, and hazardous waste. The SBR is unique from other nonsteady state biological reactors in that it has discrete fill, react, and decant periods. During the past two years, an Anaerobic Sequencing Batch Biofilm Reactor (AnSBBR) was used to select for, enrich, and modify the physiological state of a microbial consortium in order to promote the dechlorination of PCE to ethylene. The AnSBBR, fed acetate as an electron donor, dechlorinated 6.1 mg (37 pmoles) of PCE to cis- 1,2- dichloroethylene (cDCE) on a daily basis. When the daily PCE added to the reactor was increased to 80 mg (480 pmoles), the reactor produced vinyl chloride (VC) and ethylene. When the daily PCE added to the reactor was reduced to 10 mg (63 pmoles), the reactor maintained the ability to produce ethylene for approximately one month. BACKGROUND Periodic Processes for Wastewater Treatment The SBR is an activated sludge-like, periodic process that has been used effectively for the treatment of both domestic and industrial wastewaters.1-2 Reactor based periodic systems consist of one or more identically operated tanks that provide for the time sequencing of two or more processes or operations (e.g., equalization, biological conversions, and clarification) during a complete reactor cycle. Each cycle may include up to five periods: FILL, REACT, SETTLE, DRAW, and IDLE. During FILL, wastewater enters a partially-full tank containing acclimated biomass. Aerobic or anaerobic reactions can be initiated during FILL by providing either aeration or mixing. After the tank reaches its predetermined maximum liquid level, the flow is either stopped or diverted to another tank by means of a control system. The reactions initiated during FILL are continued during REACT. The time set aside for REACT must be sufficient to allow the desired effluent requirements to be met. After REACT, the biomass is allowed to SETTLE quiescently for a predetermined period of time by shutting down the mixing and aeration equipment. The treated, clarified effluent is then removed during DRAW. This tank now waits during IDLE for the liquid in the other tank to reach its maximum level so that it can begin a new cycle. As can be seen from the above description, the SBR mimics a conventional continuous flow system's treatment train by providing for piecewise equalization (during FILL), biotreatment, and sedimentation in the same tank at different times. In fact, the time set aside for each period in the SBR can be directly related to some corresponding detention time in a conventional continuous flow system (CFS). As a result, it is both appropriate and useful to equate the fraction of the time dedicated to a particular period with the fraction of the total SBR system volume that has been set aside for that period. Clearly, then, if the time (i.e., volume) allowed for one period 51st Purdue Industrial Waste Conference Proceedings, 1996, Ann Arbor Press, Inc., Chelsea. Michigan 48118. Printed in U.S.A. 289 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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