United States
Environmental Protection
 Municipal Environmental Research
 Cincinnati OH 45268
Waddell, and L. Kaplan. 1980. Removing
Potential  Organic   Carcinogens   and
Precursors from  Drinking Water. Vol. I.
EPA-600/2-80-130a,  U.S.  Environ-
mental  Protection  Agency, Cincinnati,
Ohio). This bed  life was based on the
number of days required  to  reach a
certain breakthrough of trihalomethane
formation potential  (THMFP).   The
breakthrough was the point at which the
total trihalomethanes (TTHM's) reached
100 yug/L  when   the  effluent   was
rechlorinated to  a free chlorine residual
of 2.5 mg/L and held for 2 days.
  The purpose of the present study was to
extend this bed life by using the European
method   of  ozonation  and carbon
adsorption.  This treatment technique
took advantage  of  aerobic  biological
oxidation  on granular activated carbon
(GAC).  Bed life was said to extend well
beyond the period of pure adsorption, and
the mechanism  appeared to be one by
which   biodegradable  organics   were
metabolized by bacteria growing on the
GAC. Further extension of bed life  could
reportedly be obtained by ozonation of the
water feeding the GAC adsorbers. This
ozonation was  believed to modify the
naturally occurring organics and render
them more  readily degradable by the
  Consequently,  a  22.7-m3/hr  (100-
gpm) pilot plant was designed,  construc-
ted, and operated to evaluate this process
on groundwater  in Miami, Florida. The
pilot plant was   located  at the Preston
Water Treatment  Plant in Hialeah, Florida.
The  raw  groundwater  feed was  from
wells 27.4 m (90 ft) deep on the plant site
and  contained substantial  amounts of
naturally  occurring  organics--8 to  10
mg/L total organic carbon (TOC) and 600
to 800 /ug/L THMFP.
  The pilot lant  was designed to study
parallel  systems  of GAC adsorbers that
were 3.05 m (10  ft) deep, hadanEBCTof
24.8 min, and  received  ozonated and
nonozonated, lime-softened water  that
was recarbonated to pH 8.5  and  sand
filtered. The GAC adsorbers were opera-
ted under anaerobic conditions in the
first study and aerobic conditions in the
second  study.   The  absorbed ozone
dosages in these studies were 11.3 and
14.5 mg/L, respectively. The bed life for
each of the two parallel systems  was
  In addition to the pilot studies to extend
GAC bed life, bench-scale studies  were
conducted to determine:
  1) The best of four commercially avail-
     able  GAC's for  removing  THM
     precursors  from the local ground-
  2) The bacteria profile of the Preston
     Water  Treatment Plant, including
     the distribution system.

  3) The bacteria profile of the bench-
     scale GAC work.

  4) The ability of GAC to remove agri-
     cultural  and  industrial   organic
     chemicals from waters high in TOC.

  5) The source of chloroethene com-
     pounds present in raw groundwater
     in  the  Miami  area and  in other
     locations in Florida.

  6) Removal  of volatile  halogenated
     organics  from water  by  aeration

These   studies  are  detailed   in  the
appendices to the main report.

Plant Conditions
  Conclusions in this report are based on
the  particular  groundwater feed  and
water treatment practices existing at the
Preston Water Treatment Plant during
the  study  period.  Groundwater
containing high  concentrations of TOC
and THM precursors was lime-softened,
breakpoint-chlorinated,  and sand-
filtered. Finished water leaving the plant
had a free chlorine residual of 2.5 to 3.0
mg/L for continued disinfection in the
distribution system. The average TTHM
concentration in the finished water was
150 /ug/L. This concentration increased
to 300 /ug/L in the distribution system
because of the continued reaction of free
chlorine  residual  with  precursor
substances  remaining in the  finished
  Both the original research project and
the  present study were based on the
possibility of removing enough THMFP at
the water treatment plant to limit further
growth  of   TTHM in the  distribution
system  to 100 /ug/L (assuming that the
finished water left the plant with a free
chlorine residual of 2.5 to 3.0 mg/L).
  Under the given  plant conditions, a
GAC adsorber effluent breakthrough  of
approximately 3 mg/L of TOC or  200
/ug/L of THMFP was found to produce the
100 /ug/L TTHM concentration. In this
report, bed life based on these conditions
is referred to as "Criterion 1" bed life.
Pilot Studies
  The first of the two pilot-plant studies
evaluated the effects of ozonated and
nonozonated influent on the removal of
THMFP with GAC  adsorbers  operated  |
under  anaerobic conditions.  After  the
psuedo-steady-state region of the THMFP
breakthrough curve was reached on the
GAC   adsorber  effluents,  both  GAC
adsorbers were  oxygenated for aerobic
operation to  determine whether  the
effective GAC bed life could be extended
by a change to aerobic operation.
  In the second pilot-plant study, both
ozonated and nonozonated GAC systems
were  oxygenated on  initial startup to
compare  aerobic  operation  with  the
anaerobic operation of the first study.
Other studies were conducted in the pilot
plant to determine !->ow TOC and THMFP
were   affected   by  absorbed  ozone
dosages at various pH ranges.
  Throughout all  ozone  studies,  a
complete bacterial profile was made to be
compared with  that  of  conventional
breakpoint chlorination.
 Bench-Scale Studies
  Both bench-  and pilot-scale  studies
were  conducted at the same time. The
first bench-scale project was designed to
select  the best of four commercially
available GAC's for use in the pilot plant.
Selection  was  based on the greatest  I
adsorptive capacity (longest bed life) for
removing  THM  precursors   from  the
Preston plant finished water. The  best
GAC  selected  was  then evaluated for
bed-life performance  on lime-softened
Preston  plant  water  that   was  first
adjusted to pH 8.5 by recarbonation and
then sand-filtered. This type of water feed
was  used to supply both the ozonated
systems and the nonozonated controls.
  During  the  bench-scale  studies,  a
complete bacteria profile was made for
the Preston plant.  This profile included
the distribution  system  and all bench-
scale  systems.
  Methods were developed  during the
bench-scale  studies  for   continuous
spiking   of  plant  effluents  with
agricultural and industrial   pollutants.
Studies were then made  on the removal
of these compounds by the GAC adsorbers.
Such information will be useful  if the
local  groundwater supply ever becomes
contaminated, since little is known about
the  ability  of   GAC  to remove  such
pollutants from high-TOC waters.

  Bench-scale studies were  also
conducted  to determine  the source  of
volatile, chlorinated ethene compounds
in raw groundwater in the Miami area
and in other locations in Florida.

Chemical Parameters
  1.  Of the four commercially available
     GAC's tested for THMFP removal on
     finished  water, Calgon  Filtrasorb
     400* gave the  longest  bed life and
     was selected for the pilot plant study.

  2.  When a  2.13-m (7-ft) deep bed of
     Filtrasorb  400 was  tested  for
     THMFP removal on lime-softened,
     sand-filtered water adjusted to a pH
     of 8.5, the Criterion 1 bed life was 21

  3.  In the first pilot plant study, the
     ozone- and nonozone-GAC systems
     were operated anaerobically for the
     first 98 days of the 160-day test.
     Based on Criterion 1,  the bed life
     was  44  days  for  the  ozone-GAC
     system and 19 days for the nono-
     zone  control system.

  4.  In  the  first   pilot  plant   study,
     changing from anaerobic to aerobic
     operation did not appear to alter the
     shape of the  psuedo-steady-state
     portion  of  the TOC  or THMFP
     breakthrough curves.

  5.  In the second pilot plant study, the
     ozone- and nonozone-GAC systems
     were  operated  aerobically
     throughout the full 172-day  test
     period. Based on Criterion 1, the bed
     life was 25 days for the ozone-GAC
     system and 9 days for the nonozone
     control system.

  6.  Because  the  TOC and THMFP
     loadings were  different for the two
     pilot  studies (anaerobic and aero-
     bic),   direct    comparisons   were

  7.  Ozone  in the  ozone  contractors
     greatly reduces the concentration of
     double bond chlorinated compounds.
     At an absorbed ozone dose of  14,5
     mg/L, the initial concentration of cis
     1,2-dichloroethene,  vinyl chloride
     and chlorobenzene was reduced 90,
     91 and 94 percent, respectively. At
     an absorbed dose  of  4.25  mg/L,
     these compounds were reduced 73,
     88, and 78 percent, respectively.

  8.  In a 335-day test of the removal of
     spiked organics from finished water,
'Mention of trade names or commercial products
 does not constitute endorsement or recommenda-
 tion for use
     several polyaromatic hydrocarbons
     (PAH's),  several  halogenated
     pesticides, and one polychlorinated
     biphenyl (PCB) were fed to a 0.76-m
     (2.5-ft) deep bed of Filtrasorb 400.
     During the test  period,  this GAC
     removed essentially 100 percent of
     all the PAH's, 98.6 percent of all the
     halogenated pesticides,  and 97.5
     percent of the PCB.

  9. In  an aeration system (i.e.,stirred
     beaker, aeration tower, spray head),
     the decrease in contaminant levels
     in water with time is linear if the log
     of  the effluent  concentration  is
     plotted versus   time  and  if  all
     compounds  present   are  in  the
     soluble range.

 10. When aeration decreases contami-
     nant levels in water with time, the
     decrease is independent of other
     organic  compounds when  all
     compounds  are  present  in  the
     soluble state. The decreased con-
     centration with  time  is also  inde-
     pendent of initial concentration  in
     the range of solubility.

 11. The source of volatile chloroethene
     compounds (vinyl chloride,  vinyli-
     dene chloride, cis and trans  1,2-
     dichloroethylene, etc.) in the local
     groundwater is the result of the bio-
     degradation   of   parent,   volatile
     chlorinated  degreasing   solvents
     accidentally spilled on the ground
     above  the aquifer. The  solvents
     were trichloroethylene and/or
     tetrachloroethylene.  Chlorometh-
     ane and ethane compounds are the
     result  of  the  biodegradation  of
     1,1,1 -trichloroethene.

 12. Field data  from an actual contami-
     nant  spill  in  the  environment
     confirmed the results of the labora-
     tory biodegradation studies.
Biological Parameters
  1.  In the GAC beds used to filter raw,
     lime-softened,  or chlorinated
     finished   drinking   water,   large
     numbers   of  bacteria  grew  and
     sloughed off into the water flow.

  2.  Bacteria  isolated  from the GAC
     adsorbers were common to the raw
     water supply  and  were  normal
     inhabitants of soil and fresh-water
  3. Often,  many  of  the  bacteria that
     made up the total plate counts (and
     those most frequently encountered)
     were unidentifiable by taxonomic
     keys, did not  survive subculturing,
     or  were  inert  in  standard
     biochemical tests.

  4. Common heterotrophic organisms
     recovered from  raw and treated
     water from the bench-scale tests,
     the pilot plant, and the full-scale
     treatment plant  were  species  of
     Alcaligenes. Psuedomonas, Morax-
     el la.  Acinetobacter,  Micrococcus,
     Flavobacterium, and Gram-positive

  5. The composition of the GAC effluent
     flora was generally the same as that
     of the flora on the GAC surface, but
     the species  existed in  different
     proportions. Perhaps these  results
     reflect  different resistances of the
     species to dislodgement  by the
     water flow.

  6. No real difference existed  in the
     numbers  or   kinds  of  bacteria
     recovered from the GAC  adsorber
     effluents  that  received  aerated,
     oxygenated , ozonated, or untreated
     influents. Many of the heterotrophic
     bacteria cultured from samples  of
     the GAC or their effluents were able
     to grow well  without atmospheric

  7. Bacterial populations in the GAC
     adsorbers were  dynamic. Periodic
     sampling  and analyses  indicated
     that the sizes and  compositions of
     these  populations  changed
     constantly. Probable causes were
     succession of species  within the
     adsorber and  introduction of new
     species from  the raw groundwater

  8. Gram-negative rods,  which had  no
     especially resistant forms, survived
     in  GAC effluents  that  were
     chlorinated to breakpoint and had
     up to 10 mg/L free residual chlorine
     at the time of plating.

  Ozone applied in the  12-mg/L-range
may be a desirable in-plant primary disin-
fectant for future use  in the local south
Florida area. At this concentration ozone
appears to be  as  effective as current
breakpoint chlorination  at 18 mg/L for
pathogen  and  microorganism control.

   and it  may provide even better color
   reduction.  At  this dosage, ozone also
   effectively  oxidizes  double-bond
   chlorinated compounds that are present
   in  the  raw groundwater. For  residual
   control  in the distribution system, ozone
   could be followed by a secondary disin-
   fectant  that would  not form additional
     If the local groundwater source ever
   becomes  contaminated  with  organic
   compounds that are not readily removed
   by  other  means,  the  use  of  GAC
   adsorption  in this high-TOC water would
   be very effective.
     The  full report  was  submitted  in
   fulfillment  of  Cooperative Agreement
   CR806890 by Florida International Uni-
   versity, Miami-Dade Water and Sewer
   Authority, and Dade County Department
   of Public Health under the sponsorship of
   the U.S.  Environmental Protection
          Paul R.  Wood, Frances Z. Parsons.  Russell F. Lang, Iris L. Payan, Susan S.
            Espinet-Tracey are  with Florida International University. Miami, FL 33199;
            Doris H. Waddell, Richard A. Coates, Raymond D. Diaz. Martha S. Goldberg are
            with Miami-Dade Water and Sewer Authority, Hialeah. FL 33010; and Fred W.
            Curtis, Jr.. is with Dade County Department of Public Health. Miami. FL33125.
          Jack DeMarco is the EPA Project Officer (see below).
          The complete report, entitled "Pilot Plant Project for Removing Organic
            Substances from Drinking Water." (Order No. PB 84-128 685; Cost: $29.50,
            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:
                  Municipal Environmental Research Laboratory
                  U.S. Environmental Protect/on Agency
                  Cincinnati, OH 45268
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