United States
 Environmental Protection
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA-600/S2-83-009  Apr. 1983
 Project Summary
Considerations  in  Granular
Activated  Carbon Treatment
of Combined  Industrial
 M. D. Piwoni, C. C. Lin, and W. H. Vick
  This project was initiated to investi-
gate  competitive  adsorption
phenomena and their potential impact
on  the  feasibility  of  treatment  of
combined industrial  wastewater
effluents by granular activated carbon
(GAC). Bench-scale laboratory and field
site studies were conducted to evaluate
the extent of competitive adsorption in
GAC columns.
  Laboratory studies  examined
competitive adsorption of toxic organic
chemicals from simple deionized and
complex combined  industrial
wastewater  effluent  matrices.
Chemicals, selected from a list of those
previously identified as occurring in the
wastewater. were chosen to represent a
broad range of structural and chemical
characteristics. These compounds were
spiked into the test  matrices. Results
indicated  substantial suppression  of
adsorption, and, in  some cases, the
occurrence of desorption, of some
components by other components of
the test matrix.
  Unspiked  wastewater was run
through  scaled-up GAC columns in
field  studies.  Fractionation  of  the
columns and analysis of the  fractions
revealed a transport pattern through the
column that, in general, reflected the
observations made  during the
laboratory studies using  spiked
  This Project Summary was developed
by EPA's Robert S. Kerr Environmental
Research Laboratory, Ada. OK,  to
announce key findings of the research
project that is fully  documented in a
separate report of the same title (see
Project Report ordering information at

  GAC column treatment has been under
consideration by the U.S. Environmental
Protection Agency (EPA) Effluent Guide-
lines Division as a feasible alternative for
removing low levels  of toxic  organic
compounds from complex industrial waste-
water effluents. Although the effective-
ness of GAC treatment has been clearly
demonstrated in drinking water applica-
tions, questions remain as to the appli-
cation of this methodology to considerably
more complex matrices. Competition for
adsorption sites between toxic organic
components and other organics in the
matrix  could  reduce the  removal
efficiency for compounds of concern. The
result would be premature column break-
through, and, consequently, more
frequent carbon regeneration.
  This  study examined   competitive
adsorption and its significance in treating
complex wastewaters. Bench-scale
laboratory  and  field studies were
conducted to evaluate the phenomena
and to determine the suitability of con-
ventional parameters  for  monitoring
column breakthrough.

  1.  Competition for adsorption sites on
     the carbon  surface   results  in
     certain  organic  solutes  being
     retained on the column at  the
     expense of other organics. In some

         cases, low affinity organics were
         desorbed from the carbon resulting
         in   effluent   concentrations   in
         excess of  influent levels.

     2.   The success of certain-organics in
         competing for adsorption  sites is
         related to their aqueous solubility
         and their  relative column influent
         concentrations.   Low  solubility
         components  showed  the  highest
         affinity for  the carbon although
         lower affinity compounds at higher
         relative  influent  concentrations
         are more  effective competitors.

     3.   The presence of the nondescript
         organic matrix in the wastewater
         substantially  lowered  carbon
         capacity  for  spiked  components
         when the latter were added to the
         wastewater at relatively low(5/ym)
         concentrations. At higher (100/urn)
         concentrations,  little  effect  on
         carbon capacity, compared to deion-
         ized water systems, was observed.

     4.   The shape  of the breakthrough
         curves for the organics  studied
         varied  considerably.  Some
         components  exhibited  a  sharp
         increase in  column effluent con-
         centration after initial appearance
         in the effluents while, at the other
         end  of   the  spectrum,  other
         components  increased  slowly  in
         concentration as  the  column run
         progressed.   Such   diversity   in
         column   breakthrough   patterns
         complicates the  task of  column

     5.   The  breakthrough patterns  for
         chemical  oxygen  demand (COD)
         and  total  organic  carbon (TOC)
         were  similar,  showing a  rapid
             initial breakthrough to greater than
             50  percent  followed by a  slow
             climb to total breakthrough.

         6.  The column breakthrough points of
             the  spiked  organics  were  not
             reflected by  any inflections in the
             COD or TOC curves. Under these
             study conditions,  TOC and  COD
             reflected  changes  in  the  total
             organic content  of the effluent,
             thus they were  unresponsive to
             changes  in  specific  compound

         7.  Movement  of  components  of
             interest  within carbon columns
             receiving  unspiked  wastewater
             was   generally in  accord  with
             predictions based on the results of
             the spiked components studies.

         8.  The complexity of adsorption from
             combined industrial wastewater
             effluents makes modelling of the
             system  for  specific  component
             removal  difficult if  not currently

   1.  The  competitive  adsorption
      patterns  observed in this study
      need to be generalized to all types
      of organic  compounds  requiring
      removal from wastewaters. Future
      studies should address structural
      and chemical property correlations
      to carbon column capacity as well
      as the  magnitude  of effects of
      influent concentration differences.
  2.  The magnitude of the effect of the
      nondescript  background  organic
      materials  present  in  industrial
      effluents must be better defined.
  3.  Column monitoring when removal
      of specific toxicant organics is
      required will not be possible using
      TOC or COD. Unless more refined
      surrogate  monitoring  techniques
      are  developed,  monitoring  of
      specific  components   by  gas
      chromatography  will   likely  be
          The EPA author M. D. Piwoni is with the Robert S. Kerr Environmental Research
            Laboratory, Ada, OK 74820; C. C. Lin is with the University of Texas, Dallas, TX
            75080, and; W. H. Vick is with Science Applications, Inc., LaJolla, CA 92038.
          Fred M. Pfeffer is the EPA Project Officer (see below).
          The complete report, entitled "Considerations in Granular Activated Carbon
            Treatment of Combined Industrial Wastewaters," (Order No. PB 83-164 475;
            Cost: $ 17.50, subject to change) will be available only from:
                  National Technical Information Service
                  5285 Port Royal Road
                  Springfield, VA 22161
                  Telephone: 703-487-4650
          The EPA Project Officer can be contacted at:
                  Robert S. Kerr Environmental Research Laboratory
                  U.S. Environmental Protection Agency
                  P.O. Box 1198
                  Ada, OK 74820
                                                                   ftU.S. Government Printing Office:  1983-659-017/7026
United States
Environmental Protection
Center for Environmental Research
Cincinnati OH 45268
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