United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S2-86/029 Aug. 1986
&EPA Project Summary
Groundwater and Leachate
Treatability
Studies at Four Superfund
Sites
Alan J. Shuckrow, Andrew P. Pajak, and C. J. Touhill
Bench-scale evaluations of wastewater
treatment processes were performed us-
ing contaminated groundwaters and
leachates from four hazardous waste
problem sites: (1) Ott/Story Site,
Muskegon, Michigan; (2) Gratiot County
Landfill, Gratiot County, Michigan; (3)
Marshall Landfill, Boulder, Colorado; and
(4) Olean Wellfield, Clean New York.
Processes were selected on the basis of
a previous literature review and desktop
analysis of 18 candidate processes. Treat-
ment processes reported on include ad
sorption (granular and powdered carbons,
and carbonaceous and polymeric resins),
biological treatment (activated sludge, and
upflow anaerobic filter), coagulation and
precipitation, filtration (gravity and multi-
media), ozonation, sedimentation, and
stripping (diffused aeration, packed-tower
air stripping, and packed-tower steam
stripping). Processes were used singular-
ly and in various process train
configurations.
Process performance was measured
under a range of operating conditions.
Total organic carbon (TOO was generally
used as a surrogate for routine process
monitoring, and specific compounds were
examined at selected times.
Methods and process performance
results are detailed. Because site-specific
conditions greatly influence process
performance, site-specific studies must
usually be conducted to select a viable,
cost-effective approach for a particular
problem site.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH, 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
back).
Introduction
Groundwater resources are being
threatened by a rising incidence of poor
hazardous waste disposal practices. At
many sites, the need exists to prevent fur-
ther contaminant migration and to meet
user demands for water. One way to ac-
complish these goals may be to treat con-
taminated groundwater.
Though numerous unit processes have
been demonstrated for water and
wastewater treatment, the applications do
not accurately duplicate conditions
associated with contaminated ground-
water treatment. In this research, studies
were conducted using contaminated
groundwaters from four hazardous waste
disposal sites to investigate process per-
formance under various wastewater con-
ditions. The research will aid future efforts
to formulate viable, cost-effective solu-
tions to groundwater contamination
problems.
The following unit processes have been
identified as broadly applicable to concen-
trating aqueous hazardous wastes:
biological treatment, carbon adsorption,
chemical coagulation, membrane pro-
cesses, resin adsorption, and stripping.
Chemical oxidation (e.g., ozonation) was
also judged as potentially applicable
because of its ability to enhance the
treatability of numerous organic com-
pounds. All of these processes must
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United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S2-86/029 Aug. 1986
Project Summary
Groundwater and Leachate
Treatability
Studies at Four Superfund
Sites
Alan J. Shuckrow, Andrew P. Pajak, and C. J. Touhill
Bench-scale evaluations of wastewater
treatment processes were performed us-
ing contaminated groundwaters and
leachates from four hazardous waste
problem sites: (1) Ott/Story Site,
Muskegon, Michigan; (2) Gratiot County
Landfill, Gratiot County, Michigan; (3)
Marshall Landfill, Boulder, Colorado; and
(4) Olean Wellfield, Olean, New York.
Processes were selected on the basis of
a previous literature review and desktop
analysis of 18 candidate processes. Treat-
ment processes reported on include ad
sorption (granular and powdered carbons,
and carbonaceous and polymeric resins),
biological treatment (activated sludge, and
upflow anaerobic filter), coagulation and
precipitation, filtration (gravity and multi-
media), ozonation, sedimentation, and
stripping (diffused aeration, packed-tower
air stripping, and packed-tower steam
stripping). Processes were used singular-
ly and in various process train
configurations.
Process performance was measured
under a range of operating conditions.
Total organic carbon (TOO was generally
used as a surrogate for routine process
monitoring, and specific compounds were
examined at selected times.
Methods and process performance
results are detailed. Because site-specific
conditions greatly influence process
performance, site-specific studies must
usually be conducted to select a viable,
cost-effective approach for a particular
problem site.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH, 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
back).
Introduction
Groundwater resources are being
threatened by a rising incidence of poor
hazardous waste disposal practices. At
many sites, the need exists to prevent fur-
ther contaminant migration and to meet
user demands for water. One way to ac-
complish these goals may be to treat con-
taminated groundwater.
Though numerous unit processes have
been demonstrated for water and
wastewater treatment, the applications do
not accurately duplicate conditions
associated with contaminated ground-
water treatment. In this research, studies
were conducted using contaminated
groundwaters from four hazardous waste
disposal sites to investigate process per-
formance under various wastewater con-
ditions. The research will aid future efforts
to formulate viable, cost-effective solu-
tions to groundwater contamination
problems.
The following unit processes have been
identified as broadly applicable to concen-
trating aqueous hazardous wastes:
biological treatment, carbon adsorption,
chemical coagulation, membrane pro-
cesses, resin adsorption, and stripping.
Chemical oxidation (e.g., ozonation) was
also judged as potentially applicable
because of its ability to enhance the
treatability of numerous organic com-
pounds. All of these processes must
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generally be supplemented with ancillary
processes such as sedimentation and
filtration.
Five process trains were assembled as
being broadly applicable to most types of
known contamination: (1) Biological treat-
ment and carbon sorption, (2) carbon
sorption and biological treatment, (3)
biophysical treatment, (4) membrane and
biological treatment, and (5) stripping and
carbon sorption.
Because hazardous waste contamina-
tion problems differ substantially,
treatability studies are usually required to
select the optimum treatment approach.
Using the unit processes and the process
trains listed earlier, such studies were con-
ducted for contaminated groundwater or
leachates from four Superfund sites:
• Ott/Story Site, Muskegon, Michigan
• Gratiot County Landfill, Michigan
• Marshall Landfill, Boulder County,
Colorado
• Olean Wellfield, Clean, New York
The report describes the methods used
at each site to screen treatment methods,
and it discusses the advantages and disad-
vantages of the unit processes in various
situations. Potential approaches for other
applications are also recommended.
Procedures
Bench-scale studies were used instead
of pilot-plant studies because the objec-
tive was to assess process performance
under various conditions, not to create an
optimum process for treating a particular
waste stream. Evaluations most often
began with batch tests of individual unit
processes. For selected processes or
process combinations, continuous flow or
sequential batch studies were undertaken.
Monitoring influent and effluent
chemical characteristics was potentially
complex and costly. To develop specific
compound data in a cost-and-time-
effective manner, measurements of
routine indicators or surrogate parameters
were supplemented with specific com-
pound analyses at critical times. Total
organic carbon (TOO was used as a sur-
rogate when the wastewater was
predominantly organic; heavy metals or
organic priority pollutants were analyzed
when removal of specific compounds was
of interest.
Experimental procedures generally used
to evaluate each technology are sum-
marized below.
Adsorption
Granular activated carbon (GAC) ad-
sorption studies generally began with
batch isotherm testing followed by
continuous-flow, small-diameter-column
studies. Data were used to develop
Freundlich adsorption isotherms.
Continuous-flow studies were undertaken
to examine the effects of hydraulic and
solute loading rates, and contact times, as
well as to develop solute breakthrough
curves.
Studies of powdered activated carbon
(PAC) also used batch isotherm tests.
Continuous-flow studies involved addition
of PAC to activated sludge reactors for
concurrent adsorption and biological
treatment.
Batch isotherm and continuous-flow
studies were also conducted using
polymeric and carbonaceous resins.
Biological Treatment
Biological treatment processes in-
vestigated were activated sludge, trickling
filter, and upflow anaerobic filter (UAF).
Activated-sludge processes included con-
ventional activated sludge, conventional
activated sludge with the addition of PAC
to the aeration chamber, and activated
sludge seeded with a commercial mutant
bacteria product. All systems were
operated on a continuous-flow basis us-
ing raw or pretreated wastewater. Before
process performance was assessed, at-
tempts were made to acclimate the
systems to the wastewater being
investigated.
Filtration
When wastewaters contained sus-
pended solids that were expected to inter-
fere with the primary treatment process
(e.g., by plugging the GAC adsorption col-
umn), granular media filtration was used
for pretreatment.
Ozonation
Evaluation of ozonation was conducted
on a batch basis. Ozonation was in-
vestigated as a primary treatment process
and as a pretreatment technology.
Stripping
Air stripping techniques included dif-
fused aeration as well as stripping under
mechanical mixing and quiescent con-
ditions. Air stripping was generally inves-
tigated whenever stripping was judged to
be one of several contaminant-removal
options for a particular treatment
technology, for example, during diffused
aeration, activated-sludge treatment or
ozonation.
A packed-column, continuous-flow ap-
paratus was used to evaluate steam strip-
ping. The primary operation parameters
investigated were feed flow rate and
overhead flow rate. Maintenance of
steady-state conditions proved difficult,
and the apparatus was not capable of
operating in the desired range of overhead-
to-feed flow ratio (0.02 to 0.05).
Ott/Story Site
At the Ott/Story site, groundwater has
been severely contaminated by numerous
organic compounds because of disposal
and poorly controlled storage of chemical
production wastes. Because of the com-
plex nature of the problem and the wil-
lingness of the current site owner to
cooperate with the U.S. Environmental
Protection Agency (EPA), extensive
treatability studies were conducted onsite
for an 18-month period.
Preliminary investigations focused on (1)
pretreatment by neutralization, chemical
coagulation, and precipitation, (2)
methods of solids and liquids separation,
and (3) volatility concerns. Batch studies
of individual unit processes were then
undertaken. These included air and steam
stripping, activated carbon and resin ad-
sorption, aerobic and anaerobic biological
treatment, and chemical oxidation. The
process train that performed best was
GAC adsorption followed by activated-
sludge treatment.
Air and Steam Stripping
Since most of the priority pollutants at
the site were associated with the volatile
fraction, it was concluded that (1) air strip-
ping would be the simplest approach to
removing bulk hazardous constituents,
and (2) steam stripping with reflux would
remove volatile halogenated hydrocarbons
to a greater degree and would also allow
such materials to be recovered and con-
centrated in the condensed overhead
stream, thus abating potential air pollution
problems.
In air stripping experiments, all volatile
priority pollutants were reduced to
nondetectable levels. Activated carbon
treatment of the air-sparged effluent
resulted in virtually complete removal of
the remaining basic, neutral, and acid
fractions of the priority pollutants. A
significant TOC residual remained after air
stripping and air stripping/carbon sorption
batch treatment sequences.
Though air sparging resulted in about
11% volatilization of TOC from the bulk
flow with removal of virtually all volatile
priority pollutants, steam stripping re-
moved about 34% of TOC and recovered
these organics in a more concentrated
overhead product. Air stripping appears to
be an acceptable pretreatment technique
if air emissions are judged insignificant.
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Aerated groundwater may require further
treatment for oxygen demand, trace
organics, and heavy metal removal before
discharge.
Adsorption
Isotherm studies were performed using
raw groundwater and groundwater
pretreated by aeration, ozonation,
biological treatment, and various sorbents.
Batch contact study data using raw
composite groundwater showed that sorp-
tion alone cannot achieve high degrees of
TOC removal from raw groundwater.
Similar studies were conducted using
composite groundwater pretreated by
aeration, ozonation and activated sludge,
and anaerobic treatment by upflow filter.
Except for the ozonation and activated
sludge pretreatment, sorption character-
istics were not affected, even though
initial TOC concentrations varied con-
siderably as a result of pretreatment.
The following batch sequences were
also examined: (1) air stripping followed by
carbon sorption, (2) carbon sorption
followed by air stripping, and (3) carbon
sorption followed by resin sorption.
Wastewater TOC concentration following
these treatments remained high.
The isotherm and sequential batch
studies indicated that adsorption is ap-
plicable to the situation at the Ott/Story
Site. Carbon adsorption alone and resin
sorption to a smaller extent could achieve
high degrees of removal for organic priority
pollutants. However, the adsorption
process alone could not reduce ground-
water TOC concentrations to levels
typically acceptable for direct discharge to
surface waters.
In continuous-flow studies, adsorption
was used as the primary treatment pro-
cess for both pretreatment and post-
treatment. Data indicate the following:
1. Operating at empty bed contact
times of 10 to 226 min had no con-
sistent effect on the adsorption of
TOC.
2. Adsorption capacity of the resin was
lower than that of GAC under similar
study conditions.
3. Adsorption capacity of GAC and
typical TOC breakthrough charac-
teristics were not affected by
pretreating the wastewater with
ozone.
4. Though carbon adsorption capacity
was improved by pretreating with
ozonation followed by activated
sludge, improvement in capacity was
only slightly better than demon-
strated by activated-sludge pretreat-
ment alone.
Despite the inability to maintain high
levels of TOC removal, GAC adsorption
demonstrated substantial removals of
organic priority pollutants. At a loading of
233 mg TOC/g carbon, the only priority
pollutants detected in the GAC effluent
were methylene chloride, 1, 2-dichloro-
ethane, and toluene.
Biological Treatment of Activated
Sludge
A total of 46 activated-sludge treatabili-
ty studies were conducted. Investigations
included the use of a biomass acclimated
to raw contaminated groundwater, sludge
seeded with Phenobac® , the addition of
PAC to the activated-sludge aeration
chamber, and pretreatment of ground-
water by carbon adsorption or ozonation.
Attempts to develop an acclimated
culture were minimally successful. Once
the systems were acclimated to the extent
possible, TOC removal ranged from about
35% to 60%. Though effluent TOC con-
centrations ranged from 174 to 472 mg/L,
subsequent studies indicated that the
stripping effect of diffused aeration could
account for about two thirds of the
removal.
Phenobac® , a commercially available
bacterial culture adapted for hydrocarbon
degradation, achieved an average TOC
reduction of about 48%, with a range of
37% to 58%.
Adsorption Pretreatment and
Biological Treatment
Additional activated-sludge studies
were conducted using groundwater
pretreated by (1) sorption using GAC, (2)
organic resin, (3) GAC and upflow
anaerobic filter processing, (4) chemical
oxidation by means of ozone, (5) GAC and
ozone, and (6) the addition of PAC to the
aeration chamber.
GAC pretreatment of raw groundwater
permitted development of a culture of
aerobic organisms capable of further
treating GAC effluent. More than 95%
TOC removal was achieved by this process
train during the period when the GAC
process accounted for at least 30% of the
TOC removal. Nearly all organic priority
pollutants detected in raw groundwater
were removed consistently to below the
level of detection (0.01 mg/L) by the
process train. The activated-sludge pro-
cess completely removed the few organic
priority pollutants leaking through the
GAC system, even though overall TOC
removal declined. The continued removal
of organic priority pollutants may be due
to stripping, biological degradation, or ad-
sorption to sludge floe. Greater than 99%
total phenol removal was observed.
When the pretreatment process was
converted from GAC to resin, activated-
sludge units following resin pretreatment
were not able to produce effluents con-
taining less than 100 mg/L TOC.
Anaerobic biological treatment was
selected as a candidate treatment process
because the organic content of the
groundwater was high and because
volatile priority pollutant stripping in the
activated-sludge process could be
avoided. Overall, the GAC/upflow anae-
robic filter process train, with an upper
TOC removal limit of about 81%, did not
perform as well as the GAC/activated-
sludge system.
A process train consisting of GAC, an
upflow anaerobic filter, and activated
sludge indicated that performance of the
activated-sludge process in the train is in-
versely proportional to GAC performance.
That is, as leakage from the GAC column
increased, so did the amount of overall
removal attributable to the activated-
sludge process. Data indicate that this
result may largely be due to stripping in the
aerobic system. Performance of the
system was not as good as the
GAC/activated-sludge process train.
Studies made to determine whether
ozonation enhanced adsorption or
biological treatment indicated that
preozonation did not improve activated
sludge performance, and it did not improve
performance or extend TOC breakthrough
characteristics of the GAC process.
To provide a preliminary assessment of
GAC as a polishing process, an isotherm
study was conducted with effluent from
the O3, activated sludge train using PAC.
Though batch data suggest that much
lower effluent TOC concentrations can be
produced by the train of 03, activated-
sludge, and GAC, continuous-flow opera-
tion of this train showed no advantage to
GAC polishing.
Gratiot County Landfill
The problem at the Gratiot County land-
fill in Bethany Township, Michigan, in-
volved contamination of groundwater by
polybrominated biphenyls (PBB). Because
this chemical is relatively insoluble, PBB
contamination was found to be associated
primarily with the sediment of the water
samples taken in this study. Thus it was
concluded that physical separation pro-
cesses should effect significant levels of
PBB removal. The technologies judged to
be suitable candidates were GAC adsorp-
tion, coagulation and precipitation,
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sedimentation, filtration, ion exchange,
and reverse osmosis.
The monitoring well selected for sam-
pling was the one that had previously
yielded the most highly contaminated
samples in volumes sufficient for ex-
perimental studies. Freezing was judged
to be the most suitable preservation
method. Before freezing, a representative
sample was withdrawn and analyzed for
PBB and total and dissolved metals, in-
cluding most priority pollutant metals.
Analysis indicated that metals were
predominantly in the insoluble form. By
analyzing metals that exceeded interim
primary drinking water standards or water
quality criteria, the study concluded that
granular media filtration and gravity
sedimentation could effectively remove
metals associated with silt in the sample.
Because PBB appears to be associated
with the silt, these processes should also
achieve significant levels of PBB removal.
Marshall Landfill
Marshall Landfill in Boulder County, Col-
orado, is a predominantly municipal solid
waste landfill that accepted some in-
dustrial wastes from surrounding light
manufacturing and fabricating industries.
In 1979, seepage was observed to be
draining from the fill into a small surface
waterway linked to the drinking water
supply for a nearby municipality. Analysis
of the seepage indicated presence of
numerous priority and nonpriority organic
compounds at concentrations up to 6
mg/L.
Seepage collected in an impoundment
was selected for use in laboratory evalua-
tions. Though limited composition data
were available, the TOC was significant
(168 mg/L). An adequate volume of sam-
ple for use in treatability studies could be
collected easily and dependably — an ad-
vantage that did not exist for other
locations.
Treatment techniques evaluated in-
cluded (1) batch adsorption isotherm tests
with both activated carbon and resins as
sorbents, (2) aerobic biological treatment
using activated sludge, (3) continuous-
flow GAC, (4) activated-sludge treatment
of GAC pretreated seepage, and (5) air
stripping.
In the adsorption isotherm studies, the
activated carbons effected better TOC
removal than did the resins.
Though nutrient levels, pH, dissolved ox-
ygen concentration, and heavy metal con-
centrations were within acceptable ranges
for aerobic biological treatment, attempts
at activated sludge acclimation to raw
groundwater were unsuccessful as
measured by TOC removal and biological
solids growth. Influent and effluent TOC
averaged 93 mg/L; attempts at maintain-
ing sludge solids by frequent reseeding
were unsuccessful.
Continuous-flow GAC systems were
evaluated. Influent TOC during these
studies ranged from 126 to 182 mg/L. For
the two-column system, 91% TOC
removal was achieved initially; but after
some 50 bed volumes were processed,
removal decreased to 70%. Effluent TOC
was about 40 mg/L. Data from the three-
column system indicate slightly better per-
formance at increased contact time.
To evaluate removal of organic priority
pollutants, samples of raw seepage and ef-
fluent from the three-column system were
obtained at points corresponding to TOC
breakthroughs of about 5%, 10%, and
22%. The following priority pollutants
were detected in the raw seepage but not
in the carbon column effluents: Benzene,
1,2-dichloropropane, ethylbenzene,
tetrachloroethylene, toluene, and diethyl
phthalate. No trend of increasing priority
pollutant breakthrough with increased
TOC breakthrough was apparent.
A process train consisting of GAC ad-
sorption followed by activated-sludge
treatment reduced TOC levels to 20 mg/L.
The GAC column alone reduced the TOC
to 23 mg/L, showing that the activated-
sludge process did not contribute ap-
preciably to TOC removal.
Air stripping achieved minimal TOC
removal, as expected, since Marshall Land-
fill leachate did not contain high concen-
trations of volatile priority pollutants.
Instead, it contained phenolics, aromatics,
and heavier priority pollutants with low
vapor pressures.
Olean Wellfield
In late 1981, three wells providing most
of the drinking water for Olean, New York,
were found to contain 120 to 250 f^g/L of
trichloroethylene (TCE). Because of the na-
tionwide prevalence of TCE contamination
of drinking water supplies, groundwater
from the Olean Wellfield was selected to
evaluate treatment technologies.
Samples from one well indicated that
the groundwater had a COD of 4.8 mg/L
and a TCE concentration of 46 ^g/L — well
below the anticipated concentration of
200 to 250 pg/L. Batch air stripping tests
and adsorption isotherm studies were con-
ducted with these samples.
A second set of samples was obtained
from the combined flow of two city wells.
They were found to contain 90 and 95
^g/L of TCE. Based on this analysis and
results of the air stripping and adsorption
isotherms studies, it was determined that
approximately 960 liters (250 gal) of
groundwater would be required to develop
a GAC breakthrough curve for TCE using
a bench-scale system. Isotherm studies
were repeated with this batch of sample.
Continuous-flow GAC column studies
then were conducted. A pilot test of air
stripping was conducted at Olean by the
U.S. EPA Office of Drinking Water during
the course of this study.
Adsorption isotherms were prepared for
several carbons and a carbonaceous resin.
Powdered carbon exhibited somewhat
poorer TCE adsorption characteristics.
Resin sorption data did not show a clear
trend.
Continuous-flow GAC column studies
were conducted using two columns in
series. The system was operated until the
supply of contaminated water was ex-
hausted. No TCE breakthrough was
detected at that time, even though
theoretical TCE breakthrough calculated
on the basis of Freundlich isotherm
parameters suggests that some break-
through should have been detected.
Total plate counts were made of carbon
effluent to investigate the possibility of
biological growth in the GAC columns and
subsequent contamination of the treated
water. Data indicate elevated plate counts
following GAC treatment, which may par-
tially explain the nondetectable TCE levels
in the carbon effluent. Further study in this
area may be warranted when carbon ad-
sorption systems are planned for the treat-
ment of residential or small-scale water
supplies.
Field evaluation of TCE removal by
packed-column air stripping was carried
out by the EPA Office of Drinking Water,
Technical Support Division. Their results
show that more than 99% TCE can be
removed economically by air stripping.
The full report was submitted in fulfill-
ment of Contract No. 68-03-2766 by
Michael Baker, Jr., Inc., under the sponsor-
ship of the U.S. Environmental Protection
Agency.
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