Use of Continuously Stirred Flow Systems For
Laboratory Investigation of Wastewater Treatability
With Activated Carbon
BRUCE A. BELL, Associate
Flood & Associates, Inc.
Jacksonville, Florida 32211
ALAN H. MOLOF, Associate Professor
Polytechnic Institute of New York
Brooklyn, New York 11201
INTRODUCTION
Increases in economic, population and industrial growth have led to the need for
greater quantities of clean water than are readily available in many areas. At the same time,
the ability of receiving waters to tolerate the pollutional loads of wastewaters is limited.
Thus, more and more stringent pretreatment and discharge standards are being imposed on
industry.
Activated carbon adsorption is coming into more general use in both industrial and
municipal water and wastewater treatment to remove biorefractory or toxic materials.
While general data exists as to the applicability of carbon adsorption to certain classes of
wastewater, specific designs are generally carried out utilizing laboratory and pilot testing
(I).
While the value of pilot and laboratory testing is obvious in light of the expensive
investment required in carbon systems, conventional laboratory testing is both expensive
and time consuming. The necessity of running carbon columns a sufficient length of time to
achieve carbon loadings equivalent to those expected in full scale plants makes such testing
tedious. In addition, none of the conventional methods of testing address themselves to the
kinetics of adsorption. To overcome these limitations, a laboratory technique was
developed utilizing continuously stirred flow reactors to investigate the effect of various
parameters on the kinetics of adsorption as well as capacity considerations. During the
research a model of the kinetics of adsorption was developed.
THEORETICAL CONSIDERATIONS
The existing models of adsorption of material from solution onto porous adsorbents,
such as activated carbon, have not been totally successful in describing the behavior of such
systems. The existing models range from the most common three step model of external, or
film, diffusion, intraparticle, or pore, diffusion, followed by adsorption, to multistep
models. All of the models proposed to date consider physical adsorption to be a single
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