Section 8. CHEMICAL WASTES
REMOVAL OF SPECIFIC ORGANICS FROM WASTEWATER BY
ACTIVATED CARBON ADSORPTION: EVALUATION OF A RAPID
METHOD FOR DETERMINING CARBON USAGE RATES
Bevin A. Beaudet, Senior Engineer
Louis J. Bilello, Senior Engineer
Edward M. Kellar, Engineer
J. Mark Allan, Chemist
Environmental Science and Engineering, Inc.
Gainesville, Florida 32602
Ronald J. Turner, Chemical Engineer
Industrial Pollution Control Divison, IERL-CI
Environmental Protection Agency
Cincinnati, Ohio 45268
INTRODUCTION
Since the inception of wastewater treatment with granular activated carbon (GAC), two
methods have been in general use for evaluating the feasibdity of GAC treatment and for
obtaining basic design information. The first method, the equdibrium isotherm, is limited
because it does not simulate dynamic column operation or biological effects, and it generaUy
predicts greater carbon efficiency than actually experienced in a fuU-scale system. Although
rapid and inexpensive, the isotherm is an equilibrium test for a given wastewater-carbon
system which does not provide information on the effects of system size or configuration.
The second method, the pilot-scale dynamic column test, generates information beyond
that provided by the isotherm, notably data on carbon efficiency as a function of carbon
bed depth. Pdot columns can also provide information on biological effects, assuming the
wastewater is biologically active and the duration of the study is sufficient for biological
colonies to develop.
The dynamic pilot-scale test normaUy requires many weeks of study to generate these
design data. For conventional poUutants, the cost of pUot studies is usually appreciable.
In order to generate data on specific organic contaminants, however, costs can be over-
whelming-especiaUy the analytical costs.
During the past 18 months, the U.S. Environmental Protection Agency Industrial Environmental Research Laboratory (IERL-CI) has been performing pdot-scale column tests
on-site at various organic chemical plants [ 1 ]. The purpose of this program is to generate
carbon performance data on the removal of specific organic contaminants from organic
chemicals wastewaters. The pilot tests were conducted by Environmental Science and
Engineering, Inc., (ESE) using a mobde pdot plant equipped with 4-inch internal diameter,
6-foot high columns, and a mobde analytical laboratory equipped with a gas chromatograph
and a TOC analyzer. Each test was conducted using a reactivated bituminous coal-based
carbon from an industrial source with a minimum of three carbon columns in tandem.
Each column provided 10-20 minutes empty bed contact time (EBCT). Although the
pdot-scale tests generated excellent data on carbon performance, system design criteria
and carbon usage rates for adsorption of specific organic contaminants from real-world
wastewaters, the testing costs at each plant were considerable.
The EPA recognized the need for a rapid evaluation technique which would provide
reliable information on dynamic GAC performance beyond that obtained from an isotherm.
ESE was requested to evaluate a published method of rapid carbon evaluation, which was
initially described by Rosene and Manes [2] and further investigated by the Calgon Corporation [3].
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