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Dewatering Characteristics of Sludge From Industrial Oxygen Activated Sludge Systems RONALD J. ROMAGNOLI, Environmental Engineer Environmental Systems Union Carbide Corporation South Charleston, West Virginia 25303 INTRODUCTION One of the major results of a biological wastewater treatment process is the net generation of excess biological organisms or sludge. It has been stated that the more one has of this sludge, the worse off one is. This is due to the fact that facilities require to stabilize, dewater and dispose of this material represent a very substantial portion of the cost of secondary wastewater treatment plants. The cost of sludge handling and ultimatedisposal, which some say is as much as fifty percent of the total wastewater treatment cost (1), depends not only upon the quantity of excess sludge produced but also on the physical and chemical characteristics of the sludge. Wastewater solids handling remains a very big problem in terms of cost, environmental impact, and public acceptance. Many treatment facilities in the past have tended towards the less expensive means of solids disposal such as land application or ocean dumping, and have not considered the more sophisticated solids disposal handling systems because of the economics of the situation. Wastewater treatment processes have been improving in the past few years to the point where tertiary treatment is now being considered at many sites; however, this has not been the case for the solids handling area. Unlike wastewater treatment process designs, which are based on widely studied wastewater characteristics, very little fundamental data has been collected to permit rational designs of handling systems for the wide variety of wastewater sludge solids that are produced today. Because data gaps exist in the field of wastewater solids handling, and the costs for disposing of the solids generated from waste treatment facilities are high, it is desirable to investigate the solids handling properties of each individual sludge. The Union Carbide Sludge Dewatering Laboratory provides for bench or pilot scale simulation of various waste solids treatment processes. From the data, design parameters can be determined, costs can be assigned to each unit process and the overall system can be optimized. Tests with sludges produced by the UNOX System indicate that each industrial UNOX waste activated sludge is unique in its own physical and chemical properties. The data obtained from these pilot studies may be used to directly scale up to full scale unit processes for sludge handling and disposal. Oxygen Activated Sludge Based on twenty-two side by side UNOX and air activated sludge studies, the following statements can be made pertaining to the UNOX or oxygen activated sludge: 1) Settles more rapidly and yields 2-3 percent solids concentration; 2) Is significantly less in quantity; and 3) Dewaters easier in processes such as gravity thickening, vacuum filtration and centrifugation (2). These factors indicate that capital and operating costs for sludge handling will be significantly reduced with an oxygen activated sludge system. The main hypothesis for improved settling and decreased net sludge production for oxygen-activated sludge is the maintenance of high dissolved oxygen tension in the bulk liquid. This provides the concentration gradient necessary to overcome the diffusional resistance of oxygen through the bulk floe (3). Because each floe particle is totally aerobic the entire biological mass is participating in the aerobic process. Due to the absence of any oxygen-limiting conditions, the floe can assume a more spherical and compact shape 990
Object Description
Purdue Identification Number | ETRIWC197490 |
Title | Dewatering characteristics of sludge from industrial oxygen activated sludge systems |
Author | Romagnoli, Ronald J. |
Date of Original | 1974 |
Conference Title | Proceedings of the 29th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,24462 |
Extent of Original | p. 990-1004 |
Series | Engineering extension series no. 145 |
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 | 2009-06-05 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page990 |
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 | Dewatering Characteristics of Sludge From Industrial Oxygen Activated Sludge Systems RONALD J. ROMAGNOLI, Environmental Engineer Environmental Systems Union Carbide Corporation South Charleston, West Virginia 25303 INTRODUCTION One of the major results of a biological wastewater treatment process is the net generation of excess biological organisms or sludge. It has been stated that the more one has of this sludge, the worse off one is. This is due to the fact that facilities require to stabilize, dewater and dispose of this material represent a very substantial portion of the cost of secondary wastewater treatment plants. The cost of sludge handling and ultimatedisposal, which some say is as much as fifty percent of the total wastewater treatment cost (1), depends not only upon the quantity of excess sludge produced but also on the physical and chemical characteristics of the sludge. Wastewater solids handling remains a very big problem in terms of cost, environmental impact, and public acceptance. Many treatment facilities in the past have tended towards the less expensive means of solids disposal such as land application or ocean dumping, and have not considered the more sophisticated solids disposal handling systems because of the economics of the situation. Wastewater treatment processes have been improving in the past few years to the point where tertiary treatment is now being considered at many sites; however, this has not been the case for the solids handling area. Unlike wastewater treatment process designs, which are based on widely studied wastewater characteristics, very little fundamental data has been collected to permit rational designs of handling systems for the wide variety of wastewater sludge solids that are produced today. Because data gaps exist in the field of wastewater solids handling, and the costs for disposing of the solids generated from waste treatment facilities are high, it is desirable to investigate the solids handling properties of each individual sludge. The Union Carbide Sludge Dewatering Laboratory provides for bench or pilot scale simulation of various waste solids treatment processes. From the data, design parameters can be determined, costs can be assigned to each unit process and the overall system can be optimized. Tests with sludges produced by the UNOX System indicate that each industrial UNOX waste activated sludge is unique in its own physical and chemical properties. The data obtained from these pilot studies may be used to directly scale up to full scale unit processes for sludge handling and disposal. Oxygen Activated Sludge Based on twenty-two side by side UNOX and air activated sludge studies, the following statements can be made pertaining to the UNOX or oxygen activated sludge: 1) Settles more rapidly and yields 2-3 percent solids concentration; 2) Is significantly less in quantity; and 3) Dewaters easier in processes such as gravity thickening, vacuum filtration and centrifugation (2). These factors indicate that capital and operating costs for sludge handling will be significantly reduced with an oxygen activated sludge system. The main hypothesis for improved settling and decreased net sludge production for oxygen-activated sludge is the maintenance of high dissolved oxygen tension in the bulk liquid. This provides the concentration gradient necessary to overcome the diffusional resistance of oxygen through the bulk floe (3). Because each floe particle is totally aerobic the entire biological mass is participating in the aerobic process. Due to the absence of any oxygen-limiting conditions, the floe can assume a more spherical and compact shape 990 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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