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34 THE EFFECTS OF A SURFACTANT ON POST-EXTRACTION TREATMENT OF PCE CONTAMINATED WATER Stefanie R. Lange, Research Associate Clifford R. Lange, Assistant Professor Department of Civil Engineering Auburn University Auburn, Alabama 36830 INTRODUCTION Remediation of contaminated groundwater has long been a concern of environmental engineers and scientists. One category of environmentally important contaminants is chlorinated hydrocarbons. Chlorinated hydrocarbons in the environment are generally present in the form of Dense Non-Aqueous Phase Liquids (DNAPLs) because of their high molecular weight and relatively low solubility in water. High densities combined with low viscosities make remediation of chlorinated solvents difficult.' One specific chlorinated hydrocarbon of interest is tetrachloroeth- ylene, also known as perchloroethylene (PCE), which is a solvent used in dry cleaning and de- greasing. PCE has been a commonly encountered contaminant at remediation sites due to industrial discharges, municipal waste treatment plant discharges, and spills. Pump and treat extraction has been the most widely used form of aquifer remediation for PCE contaminated groundwater sites. However, large pumping volumes and long pumping times are required to effectively remediate these sites. Recently, investigations have been conducted to assess the feasibility of surfactant enhanced pump and treat techniques. These investigators have demonstrated that Surfactant Enhanced Aquifer Remediation (SEAR) can greatly reduce the volume of water required to flush PCE from a contaminated groundwater site.1 Surfactants are able to increase the apparent solubility and mobility of PCE.2 This allows the PCE to go into solution and decreases liquid surface tension causing the PCE to be more readily transported out of the groundwater through pumping. However, little research has been done concerning the treatment of these wastes containing surfactants after they have been pumped out of the groundwater. The presence of surfactants in a wastewater solution complicates the mechanisms controlling the adsorption of PCE onto granular activated carbon. It is hypothesized that competition exists between the carbon and the surfactant micelles for PCE adsorption. PCE bound in surfactant micelles can pass through a carbon column without being adsorbed. The surfactants also block the pore structure of the activated carbon, resulting in reduced absorbent surface area. It has been observed that the rate of PCE adsorption by sand is controlled by intraparticle-pore diffusion,1 indicating that the potential for fouling of pores by surfactants can have a negative affect. Additionally, the surfactant can coat the surface of the carbon, which will alter the surface properties of the absorbent.4 Surfactant in wastewater solutions also present problems for air stripping due to changes in solubility and the generation of foaming. Further, surfactants alter the rate of mass transfer into the gas bubble, reducing the mass transfer coefficient,5 and thereby slowing the air stripping process. 52nd Purdue Industrial Waste Conference Proceedings. 1997. Ann Arbor Press. Chelsea. Michigan 48118. Printed in U.S.A. 343
Object Description
Purdue Identification Number | ETRIWC199734 |
Title | Effects of a surfactant on post-extraction treatment of PCE contaminated water |
Author |
Lange, Stephanie R. Lange, Clifford R. |
Date of Original | 1997 |
Conference Title | Proceedings of the 52nd Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,20307 |
Extent of Original | p. 343-348 |
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 | 2009-11-03 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 343 |
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 | 34 THE EFFECTS OF A SURFACTANT ON POST-EXTRACTION TREATMENT OF PCE CONTAMINATED WATER Stefanie R. Lange, Research Associate Clifford R. Lange, Assistant Professor Department of Civil Engineering Auburn University Auburn, Alabama 36830 INTRODUCTION Remediation of contaminated groundwater has long been a concern of environmental engineers and scientists. One category of environmentally important contaminants is chlorinated hydrocarbons. Chlorinated hydrocarbons in the environment are generally present in the form of Dense Non-Aqueous Phase Liquids (DNAPLs) because of their high molecular weight and relatively low solubility in water. High densities combined with low viscosities make remediation of chlorinated solvents difficult.' One specific chlorinated hydrocarbon of interest is tetrachloroeth- ylene, also known as perchloroethylene (PCE), which is a solvent used in dry cleaning and de- greasing. PCE has been a commonly encountered contaminant at remediation sites due to industrial discharges, municipal waste treatment plant discharges, and spills. Pump and treat extraction has been the most widely used form of aquifer remediation for PCE contaminated groundwater sites. However, large pumping volumes and long pumping times are required to effectively remediate these sites. Recently, investigations have been conducted to assess the feasibility of surfactant enhanced pump and treat techniques. These investigators have demonstrated that Surfactant Enhanced Aquifer Remediation (SEAR) can greatly reduce the volume of water required to flush PCE from a contaminated groundwater site.1 Surfactants are able to increase the apparent solubility and mobility of PCE.2 This allows the PCE to go into solution and decreases liquid surface tension causing the PCE to be more readily transported out of the groundwater through pumping. However, little research has been done concerning the treatment of these wastes containing surfactants after they have been pumped out of the groundwater. The presence of surfactants in a wastewater solution complicates the mechanisms controlling the adsorption of PCE onto granular activated carbon. It is hypothesized that competition exists between the carbon and the surfactant micelles for PCE adsorption. PCE bound in surfactant micelles can pass through a carbon column without being adsorbed. The surfactants also block the pore structure of the activated carbon, resulting in reduced absorbent surface area. It has been observed that the rate of PCE adsorption by sand is controlled by intraparticle-pore diffusion,1 indicating that the potential for fouling of pores by surfactants can have a negative affect. Additionally, the surfactant can coat the surface of the carbon, which will alter the surface properties of the absorbent.4 Surfactant in wastewater solutions also present problems for air stripping due to changes in solubility and the generation of foaming. Further, surfactants alter the rate of mass transfer into the gas bubble, reducing the mass transfer coefficient,5 and thereby slowing the air stripping process. 52nd Purdue Industrial Waste Conference Proceedings. 1997. Ann Arbor Press. Chelsea. Michigan 48118. Printed in U.S.A. 343 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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