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ROTATING BIOLOGICAL CONTACTOR TREATMENT OF HYPERSALINE WASTES Paul L. Bishop, Associate Professor Nancy E. Khmer, Graduate Student Department of Civil Engineering University of New Hampshire Durham, New Hampshire 03824 Many industrial manufacturing processes generate wastewaters containing high salinity. For example, tannery wastes, pickle processing wastes, oil field brines and many chemical production wastes contain high concentration of chloride. This can have a serious impact on wastewater treatment since high chloride concentrations can inhibit or impair the microorganisms operating in the biological treatment system. Several biological treatment methods have been evaluated for dealing with these wastes, including both suspended growth and fixed growth systems, with varying degrees of success. This research was performed to examine the effects of high salinity on the operating of rotating biological contactors or RBCs. Structurally, RBCs are composed of circular plastic media mounted centrally on a horizontal shaft with the assembly partially submerged in a tank containing wastewater. The shaft is rotated to alternately provide wetting of the disks with wastewater followed by contact with atmospheric oxygen. To increase the efficiency of the treatment process, the tank is normally divided into several compartments, each containing a section of media. Various types of media are manufactured with high density designs to maximize the surface area per unit volume available to microorganisms for attachment. Disk diameters range from 0.5 to 3.7 meters. The characteristics of activated sludge dispersed cultures and trickling filter attached bio- films are combined in RBCs. During the start-up period microorganisms adhere to the disk surfaces and within one to four weeks a significant biofilm develops. Up to 97% of the carbonaceous biochemical oxygen demand (BOD) can be converted by suspended floes in the liquid phase and by the biofilm on the medium into new cell biomass, effectively removing this material from the waste stream. The biofilm continually sloughs off the disk after it has reached some critical thickness and is removed from the effluent along with the suspended floes by second clarificiation. LITERATURE REVIEW Until recently there has been little concentrated research in the area of hypersaline wastewater treatment. Most of the research on saline biological wastewater treatment has been conducted using the activated sludge process [1-4], especially extended aeration [5,6]. Only a few studies have used trickling filters [7-9|. These studies concluded that, with an acclimation period of 1 to 3 weeks, freshwater bacterial cultures subjected to salinities up to 35,000 mg/1 could attain organic removals equivalent to those obtained during non-saline operation. Shock loading with wastewater of varying salinity, however, could impair the removal capacity of the biological growth. Most previous research on saline domestic wastewater treatment has been conducted on the activated sludge process. Using a bench scale unit Ludzack and Noran [3] found that free swimming ciliates survived in a continuous high chloride artificial waste made from NaCl (3.5% salinity). When the chloride content alternated between high and low concentrations, 644
Object Description
Purdue Identification Number | ETRIWC198167 |
Title | Rotating biological contactor treatment of hypersaline wastes |
Author |
Bishop, Paul L. Kinner, Nancy E. |
Date of Original | 1981 |
Conference Title | Proceedings of the 36th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,32118 |
Extent of Original | p. 644-654 |
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 | 2009-07-07 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 644 |
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 | ROTATING BIOLOGICAL CONTACTOR TREATMENT OF HYPERSALINE WASTES Paul L. Bishop, Associate Professor Nancy E. Khmer, Graduate Student Department of Civil Engineering University of New Hampshire Durham, New Hampshire 03824 Many industrial manufacturing processes generate wastewaters containing high salinity. For example, tannery wastes, pickle processing wastes, oil field brines and many chemical production wastes contain high concentration of chloride. This can have a serious impact on wastewater treatment since high chloride concentrations can inhibit or impair the microorganisms operating in the biological treatment system. Several biological treatment methods have been evaluated for dealing with these wastes, including both suspended growth and fixed growth systems, with varying degrees of success. This research was performed to examine the effects of high salinity on the operating of rotating biological contactors or RBCs. Structurally, RBCs are composed of circular plastic media mounted centrally on a horizontal shaft with the assembly partially submerged in a tank containing wastewater. The shaft is rotated to alternately provide wetting of the disks with wastewater followed by contact with atmospheric oxygen. To increase the efficiency of the treatment process, the tank is normally divided into several compartments, each containing a section of media. Various types of media are manufactured with high density designs to maximize the surface area per unit volume available to microorganisms for attachment. Disk diameters range from 0.5 to 3.7 meters. The characteristics of activated sludge dispersed cultures and trickling filter attached bio- films are combined in RBCs. During the start-up period microorganisms adhere to the disk surfaces and within one to four weeks a significant biofilm develops. Up to 97% of the carbonaceous biochemical oxygen demand (BOD) can be converted by suspended floes in the liquid phase and by the biofilm on the medium into new cell biomass, effectively removing this material from the waste stream. The biofilm continually sloughs off the disk after it has reached some critical thickness and is removed from the effluent along with the suspended floes by second clarificiation. LITERATURE REVIEW Until recently there has been little concentrated research in the area of hypersaline wastewater treatment. Most of the research on saline biological wastewater treatment has been conducted using the activated sludge process [1-4], especially extended aeration [5,6]. Only a few studies have used trickling filters [7-9|. These studies concluded that, with an acclimation period of 1 to 3 weeks, freshwater bacterial cultures subjected to salinities up to 35,000 mg/1 could attain organic removals equivalent to those obtained during non-saline operation. Shock loading with wastewater of varying salinity, however, could impair the removal capacity of the biological growth. Most previous research on saline domestic wastewater treatment has been conducted on the activated sludge process. Using a bench scale unit Ludzack and Noran [3] found that free swimming ciliates survived in a continuous high chloride artificial waste made from NaCl (3.5% salinity). When the chloride content alternated between high and low concentrations, 644 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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