25    SYSTEMATIC APPROACH FOR THE SELECTION OF THE
LEAST COST TREATMENT TECHNOLOGY FOR
AQUEOUS ORGANIC
HAZARDOUS AND INDUSTRIAL WASTES
Bruce I. Dvorak, Graduate Research Assistant
Desmond F. Lawler, Associate Professor
Department of Civil Engineering
University of Texas
Austin, Texas 78712-1076
Darrell L. Jones, Staff Engineer
Radian Corp.
Austin, Texas 78720
Deborah A. Boadway, Project Engineer
County Sanitation Districts of Los Angeles County
Whittier, CA 90607
Gerald E. Speitel Jr., Assistant Professor
Department of Civil Engineering
University of Texas at Austin
Austin, Texas 78712-1076
INTRODUCTION
Environmental engineers frequently face difficult design decisions in selecting the proper technology for the treatment of waters contaminated with organic chemicals. The two most common treatment methods are air stripping and carbon adsorption. However, concerns about air pollution from
stripping towers sometimes necessitates using gas phase controls. Therefore three treatment options
are usually considered: air stripping alone, air stripping followed by gas phase adsorption, and liquid
phase adsorption. In this research, a rational method for selection among these treatment options was
investigated. Mathematical models have been used to draw generalizations concerning the choice
among the options.
Compounds selected for study were synthetic organic chemicals that had been found previously in
places and levels sufficient to cause environmental concern. The compounds selected were benzene,
chloroform, trichloroethene (TCE), dibromochloropropane (DBCP), phenol, 1,1-dichloroethane
(1,1-DCA), methyl tertiary butyl ether (MTBE), and a hypothetical component (XXX). These compounds respresented a broad range of stripping and adsorption characteristics. A liquid flow rate of
1000 gpm (1.44 MGD) and an influent water temperature of 20°C was used. High concentration
(typical of some leachate and industrial wastes) and low concentration (typical of contaminated
groundwater) cases were studied.
BACKGROUND AND DEVELOPMENT OF MATHEMATICAL MODELS
Air Stripping
The theories of gas transfer and of packed tower aeration are well known and are found in
numerous places in the technical literature. Only a brief review of some pertinent equations and
terminology is given. Henry's law describes the linear relationship between liquid and gas phase
concentrations at equilibrium:
CG = H C. (1)
46th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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