An Evaluation of Rotary Air Stripping for Removal of Volatile Organics from Ground Water


Book Description

Rotary air stripping was researched and developed to remove volatile organic contaminants from groundwater. The Traverse Group, Inc, Ann Arbor MI, was contracted under a joint funding venture by the US Coast Guard and the US Air Force to evaluate feasibility of using rotary air stripping to treat water contaminated with benzene, toluene, xylenes, trichloroethylene, 1,2,dichloroethane, and tetrachloroethylene. A site of groundwater contamination at the US Coast Guard Station, Traverse City MI provided a readily available source of contaminated water for this work. A prototype rotary air stripper (RAS), manufactured specifically for this project, was installed onsite in Traverse City MI. The RAS (consisting of a packed bed 1.7 feet in diameter by 1.2 feet thick) was evaluated over a range of contaminant concentrations (63 to 19,000 ppb), liquid flow rates (50 to 120 gpm), air to water ratios (10:1 to 170:1 vol/vol), and rotor speeds (365 to 875 rpms). The effect of each parameter on removal efficiency was analyzed. Generally, removal efficiencies in excess of 99 percent were achieved for all contaminants (except 1,2-DCE) at an air-to-water ratio and rotor speed of 30:1 vol/vol and 435 rpms, respectively. Keywords: Water treatment, Air stripping, Rotary Air Stripper, Hazardous materials, Rotating packed beds, Acceleration, Mass transfer coefficients, Benzene, Toluene, Xylenes, Fuel contamination, Chlorinated organics.




Economic Evaluation of Air Stripping to Remove Volatile Organic Compounds from Water


Book Description

This report documents the results of a study conducted to provide a basis for estimating the costs of installing and using air stripping to remove volatile organic compounds (VOCs) from water. The air stripping technology was found to be a very economical and efficient method for contaminant removal. The technology is simple, relatively inexpensive to install, and has low labor and maintenance requirements. VOC removal rates range from 90 to 99.99 percent. Estimated costs, in terms of percentage of total production costs, were found to be 40 percent for capital costs, 50 percent for operational costs, and 10 percent for maintenance costs, according to literature sources. Results of a survey conducted during this study generally agree with these percentages, except that maintenance costs reported on the survey were lower due to the highly automated nature of new installations.













Air Stripping Pilot Study of VOC (Volatile Organic Compounds)-Contaminated Ground Water. Volume 1. General Engineering Aspects


Book Description

Environmental Science and Engineering, Inc. (ESE) performed a series of test runs in a packed column air stripper to determine performance for removal of four volatile contaminants. Test results were used to determine effect of various conditions such as matrix, contaminant concentration, stripper configuration, and temperature on stripper performance for treating ground water at various Department of the Army installations.




An Introduction to Air Stripping to Remove VOCs from Water


Book Description

Introductory technical guidance for civil, environmental and mechanical engineers and construction managers interested in removal of volatile organic compounds from water streams using air stripping technology. Here is what is discussed: 1. INTRODUCTION 2. DESCRIPTION OF AIR STRIPPERS 3. DESIGN METHODS 4. TREATABILITY 5. COMPARISON OF AIR STRIPPERS 6. AIR POLLUTION CONTROL REQUIREMENTS 7. FLOODING 8. PROCESS CONTROL 9. ECONOMIC EVALUATION 10. REFERENCES.




Combined Air Stripper/membrane Vapor Separation Systems. [Volatile Organic Compounds].


Book Description

Air stripping is an economical and efficient method of removing dissolved volatile organic compounds (VOCs) from contaminated groundwater. Air strippers, however, produce a vent air stream, which must meet the local air quality limits. If the VOC content exceeds the limits, direct discharge is not possible; therefore, a carbon adsorption VOC capture system is used to treat the vent air. This treatment step adds a cost of at least $50/lb of VOC captured. In this program, a combined air stripper/membrane vapor separation system was constructed and demonstrated in the laboratory. The membrane system captures VOCs from the stripper vent stream at a projected cost of $15/lb VOC for a water VOC content of 5 ppmw, and $75/lb VOC for a water VOC content of 1 ppmw. The VOCs are recovered as a small, concentrated liquid fraction for disposal or solvent recycling. The concept has been demonstrated in experiments with a system capable of handling up to 150,000 gpd of water. The existing demonstration system is available for field tests at a DOE facility or remediation site. Replacement of the current short air stripping tower (effective height 3 m) with a taller tower is recommended to improve VOC removal.




Advanced Physicochemical Treatment Processes


Book Description

The past thirty years have witnessed a growing worldwide desire that po- tive actions be taken to restore and protect the environment from the degr- ing effects of all forms of pollution—air, water, soil, and noise. Because pollution is a direct or indirect consequence of waste, the seemingly idealistic demand for “zero discharge” can be construed as an unrealistic demand for zero waste. However, as long as waste continues to exist, we can only attempt to abate the subsequent pollution by converting it to a less noxious form. Three major questions usually arise when a particular type of pollution has been id- tified: (1) How serious is the pollution? (2) Is the technology to abate it ava- able? and (3) Do the costs of abatement justify the degree of abatement achieved? This book is one of the volumes of the Handbook of Environmental Engineering series. The principal intention of this series is to help readers f- mulate answers to the last two questions above. The traditional approach of applying tried-and-true solutions to specific pollution problems has been a major contributing factor to the success of en- ronmental engineering, and has accounted in large measure for the establi- ment of a “methodology of pollution control. ” However, the realization of the ever-increasing complexity and interrelated nature of current environmental problems renders it imperative that intelligent planning of pollution abatement systems be undertaken.