SEPA
United States
Environmental Protection
Agency
Robert S Kerr Environmental Research
Laboratory
Ada OK 74820
Research and Development
EPA-600/S2-81-067 July 1981
Project Summary
Evaluation of the Effectiveness
of Granular Activated Carbon
Adsorption and Aquaculture for
Removing Toxic Compounds
From Treated Petroleum
Refinery Effuents
John E. Matthews
The effectiveness of granular acti-
vated carbon for removal of selected
priority pollutants from petroleum
refinery wastewaters was evaluated
under both laboratory and field condi-
tions. The effectiveness of aquacul-
ture was evaluated under field condi-
tions.
Activated carbon adsorption iso-
therms of prepared aqueous solutions
of toluene, 2,4-dimethylphenol, naph-
thalene, benzo(a)pyrene, chrysene,
pyrene, acenapthene, phenanthrene,
fluoranthene, and fluorene were deter-
mined by laboratory studies to estimate
the optimum loading capacity under
ideal conditions. The adsorption ca-
pacity and loading capacity of the
pulverized activated carbon for the
specific organic compounds were
calculated with the Freundlich equa-
tion.
Effectiveness of activated carbon
and aquaculture for removal of organic
compounds from a treated petroleum
refinery wastewater was evaluated
with a pilot-scale treatment system
onsite at a refinery. Comparison of
effluent quality from the activated
carbon columns versus conventional
biological treatment in aerated lagoons
as measured by chemical criteria and
continuous flow bioassays showed
the activated carbon to be effective in
removing organic compounds and re-
ducing toxicity of the wastewater. A
pilot-scale aquaculture treatment
system was also shown to be effective
in reducing toxicity of the treated
wastewater.
A literature review of activated
carbon treatment indicated consider-
able variation in estimates for both
capital investments and annual oper-
ating costs. Capital investment costs
for granular activated carbon facilities'
ranged from $540,000 - $2,300,000
(1970) to $587,000 - $3,175,000
(1978) for plants from 1 to 20 million
gallons per day. Annual operating
costs for granular activated carbon
systems varied from 4.80 to 400 per
1,000 gallons of water treated de-
pending upon type of wastewater and
amount of pretreatment.
This Project Summary was devel-
oped by EPA's Robert S. Kerr Environ-
mental Research Laboratory, Ada,
OK, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Because of the intensified interest in
the removal of toxic pollutants from
petroleum refinery effluents, an evalu-
ation of the effectiveness of treatment
schemes necessary to accomplish this
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removal is required. Activated carbon is
well known, as a good adsorbent for
removal of organic compounds from
aqueous solutions and has been pro-
posed as a relatively efficient method for
removing organicsfrom refinery waste-
waters. Aquaculture is a potential in-
expensive mode of treatment for re-
moval of dilute concentrations of toxic
pollutants.
Under the sponsorship of the U.S.
Environmental Protection Agency's
Robert S. Kerr Environmental Research
Laboratory, the effectiveness of activated
carbon for removal of selected priority
pollutants from petroleum refinery ef-
fluents was evaluated under both labo-
ratory and field conditions. The effec-
tiveness of aquaculture in removing
toxic compounds from treated refinery
effluents was evaluated under field
conditions.
Adsorption isotherms of prepared
aqueous solutions were determined for
10 specific priority pollutants identified
in the 1976-1977 EPA survey of petro-
leum refinery wastewaters: toluene,
2,4-dimethylphenol, naphthalene,
benzo(a)pyrene, chrysene, pyrene,
acenapthene, phenanthrene, fluoran-
thene, and fluorene.
In addition, effectiveness of activated -
carbon for removal of toxic compounds
from a petroleum refinery wastewater
was evaluated with a pilot-scale treat-
ment system onsite at a refinery. The
criterion for determining the effective-
ness of removal was toxicity reduction
as measured by continuous flow bio-
assays. A comparison of the effluent
quality from three modes of treatment—
conventional biological, dual-media
filtration-activated carbon (DM-AC),
and pilot-scale aquaculture—was made
based on chemical measurements and
continuous-flow bioassay results.
The final objective of this project was
to review the literature on the cost of
activated carbon adsorption as a treat-
ment mode for removing organic com-
pounds from petroleum refinery waste-
waters.
Process
Adsorption Isotherms
Aqueous solutions of the specific
chemical compounds were prepared,
and isotherm tests (using pulverized
granular activated carbon) were con-
ducted for each compound. Thequantity
of 2,4-dimethylphenol and toluene re-
maining in aqueous solutions after
contact with the carbon was analyzed
'with a total organic carbon instrument.
The concentration of naphthalene,
benzo(a)pyrene, chrysene, pyrene,
acenapthene, phenanthrene, fluorari-
thene, and fluorene was determined
using a Fluorescent Spectrophotometer.
Data were analyzed by the Freundlich
equation:
x _
m
.= KC,1/n
where:
x = q ua ntity of sol ute adsorbed
in mg
m = weight of carbon in g
K = intercept at Cf = 1
C( = final quantity of solute in
mg
1 /n = slope of the line.
Onsite Evaluations
A pilot-scale DM-AC treatment sys-
tem mounted in a mobile trailer was
located onsite at an oil refinery. The
dual-media filter column was filled
sequentially with pea-sized gravel (10
cm), #1220 garnet sand (35 cm), and #2
anthracite coal. The filtration column
was designed for downflow gravity fil-
tration with valving for hydraulic back-
flushing.
Following filtration, the system was
designed for sequential flow through a
series of four activated carbon columns.
Each column was filled with approxi-
mately 13.5 kg (152 cm in column) of
granular activated carbon. Carbon was
changed prior to exceeding a loading
capacity of 1 g of COD per 10 g of
carbon.
A pilot-scale aquaculture treatment
system was constructed onsite at the
refinery. The major components of the
aquaculture system consisted of a se-
quential series of six pools. Each pool
was 5.48 m in diameter and 1.2 m in
depth. The first three pools in the series
were operated for optimum growth of
algae. The fourth pool was stocked with
2,898 kg/ha of mussels and 951 kg/ha
of Tilapia Aurea. The fifth pool was
stocked with 7,730 kg/ha of mussels
and 2,183 kg/ha of Tilapia. The sixth
pool was stocked with 2,319 kg/ha of
mussels, 2,533 kg/ha of Tilapia, and
0.93 m2 of the emergent plant, Primrose
Willow (Jussiaea diffusa). Flow rate of
the wastewater through the aquaculture
system was maintained at 3 to 4 liters
per minute for an estimated retention
time of 3.7 to 5 days per pool.
Influent water to the pilot-scale aqua-
culture and DM-AC treatment systems
was pumped from the point of final dis-
charge from the oil refinery treatment
system. The refinery treatment system
consisted of sequential treatment with a
primary API separator, dissolved air
•flotation unit, aerated lagoon, and
waste stabilization lagoons. Water from
each of the test units passed through
duplicate artificial streams for perform-
a*nce of continuous-flow bioassays
using benthic macroinvertebrates and
fish. Assemblages of macroinvertebrates
were collected from a natural stream
using Hester-Dendy samplers. Nine of
these samplers were placed in each
artificial stream. Ten caged fathead
minnows were also placed in each
artificial stream.
Results
Nine of the ten compounds tested
showed a good positive correlation with
the Freundlich equation (Table 1). Ad-
sorption data for benzo(a)pyrene (BAP)
did not fit the Freundlich equation but
did show a high correlation with a
normal arithmetic linear regression
equation when the dose of carbon was
plotted against the quantity of BAP
adsorbed. Apparently the sorption
mechanism for BAP was different from
the other compounds.
Except for toluene, the adsorption
capacity appeared to decrease with
respect to an increase in complexity of
the polynuclear aromatic molecule.
Although toluene data showed an excel-
lent fit with the Freundlich equation, the
actual loading factor for toluene appears
to be lower than would be predicted for
the physical-chemical properties of the
compound.
The adsorption isotherm data indicate
that activated carbon could be used to
remove polynuclear aromatic hydrocar-
bon compounds from aqueous wastes.
However, relatively high dosages of
carbon would be required to remove the
five-membered aromatic ring compounds
such as chrysene and BAP. For example,
it would require 1,667 mg/l of activated
carbon to reduce the concentration of
chrysene from 0.01 mg/l to 0.001 mg/l
in a single-stage contactor, calculated
from the Freundlich equation.
Onsite Evaluations
The final effluent from the aerated
lagoon treatment system at this refinery
was of good quality with respect to the
chemical criteria specified in the NPDES
effluent guidelines. '
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The total cumulative mortality of
fathead minnows exposed to the normal
lagoon effluent was 25 percent (Table
2). In contrast, no mortality was observed
during the 32-day exposure of the fish to
either of the pilot-scale advanced treat-
ment systems.
The number of species of benthic
macroinvertebrate organisms was higher
after exposure to the two pilot-scale
treatment system than that of the
aerated lagoon effluents (Table 3). Also,
the mean density of individuals of
macroinvertebrate organisms exposed
to the pilot system effluents was over
100 percent higher than that of the
aerated lagoon effluent.
The DM-AC treatment system reduced
the BOD5, COD, TOC, and TSS concen-
trations of the aerated lagoon effluent
by approximately 50, 75,75, and 60 per-
cent, respectively (Table 4). There were
no significant differences in concentra-
tions of nitrate-nitrogen and total phos-
Table 1. Summary of Freundlich Parameters
Compound
Fluorene
2,4 dimethylphenol
Acenaphthene
Phenanthrene
Naphthalene
Fluoranthene
Pyrene
Toluene
Chrysene
Benzo(a)pyrene
Ka>
196
184
140
135
123
88
66
40
6
(b)
1/n
0.57
0.09
0.43
0.45
0.41
0.38
0.24
0.35
0.50
(b)
r
0.95
0.93
0.97
0.89
0.99
0.82
0.92
0.93
0.82
-0.55
fa) K at C0 - mg/l.
(b) data did not fit Freundlich Equation, as indicated by low correlation coefficient.
r = correlation coefficient.
Table 2. Percent Mortality of Fathead Minnows (Pimephales Promelas)
Treatment System
Days of Exposure
Aerated
lagoon
Aquaculture
DM-AC
Percent mortality of replicates
9/1 8/78 Start
8
11
16
22
24
29
32
0
0
0
10
5
0
5
5
0
0
0
0
O
0
0
0
0
0
0
0
O
0
0
0
Total Cumulative Mortality
25
Table 3. Response of Benthic Macroinvertebrate Organisms to Selectively
Treated Oil Refinery Wastewater
Number of species
Mean density"
Aerated Aerated
Days of Exposure lagoon Aquaculture DM-AC lagoon Aquaculture DM-AC
9/1 8/78 Start
8
16
32
44
38
39
22
44
35
40
39
44
44
41
36
2243
2985
5219
4689
2243
1804
5262
10113
2243
3868
6226
12352
"Number of organisms/'m2.
phate-phosphorus. The aquaculture
system reduced the BOD5, nitrate,
phosphate, and TSS concentrations by
approx;mately 60,90,55, and 60 percent,
respectively. There were no significant
differences in COD and TOC concentra-
tions.
Economics
A literature review of activated carbon
treatment indicates considerable varia-
tion in estimates of both capital invest-
ments and annual operating costs.
Estimation of treatment costs is difficult,
since each system reacts differently.
Comparison of design criteria is also
difficult, since systems may have differ-
ent design parameters. Capital invest-
ment costs for 1 to 20 million gallons per
day (MGD) granular activated carbon
treatment facilities ranged from $540,000
to $2,300,000 (1970) to $587,000 to
$3,175,000 (1978). Estimated capital
investment costs for powdered activated
carbon treatment systems of 2 to 20
MGD capacity ranged from $406,000 to
$912,000 with regeneration capabilities
and $123,000 to $1,050,000 without
regeneration capabilities.
Annual operating costs for granular
activated carbon systems varied from
4.80 to 40C per 1,000 gallons of water
treated, depending upon the type of
wastewater and the amount of pretreat-
ment. Operating costs for powdered
carbon systems varied from 1.50 to 7.00
per 1,000 gallons treated, depending on
influent flow and quality.
Conclusions
Activated carbon was shown to be
effective in removing selected organic
compounds from petroleum refinery
wastewaters; however, there was a
wide variation in the adsorption capaci-
ties of the 10 compounds tested. In
general, adsorption capacity of activated
carbon appears to decrease with an
increase in the complexity of the poly-
nuclear aromatic molecule; therefore, it
would require relatively high dosages of
carbon to remove the five-membered
aromatic ring compounds such aschry-
sene and benzo(a)pyrene. As calculated
from the Freundlich isotherm, it would
require 1,667 mg/l of activated carbon
to reduce the concentration of chrysene
from 0.01 mg/l to 0.001 mg/l in a
single-stage contactor.
Advanced treatment using activated
carbon or aquaculture appears to signif-
icantly improve petroleum refinery
wastewater with respect to toxicity
u US GOVERNMENT PRINTING OFFICE 1981-757-012/7163
-------
reduction. There were no fathead min-
now mortalities in either effluent during
the 32-day study. In addition, the variety
and abundance of benthic macroinver-
tebrates increased in the effluents of
both pilot-scale advanced treatment
systems.
Table 4. Mean Chemical Measurements for Selectively Treated Petroleum
Refinery Effluents
Mean concentration (mg/l)
Chemical Parameter Aerated lagoon Aquaculture
DM-AC
BOD,,
COD
TOO
TSS
Nitrate-Nitrogen
Total Phosphate-Phosphorus
20.2
128.1
45.1
33.0
3.65
0.22
8.1
137.0
46.9
19.0
0.45
0.10
9.9
31.4
11.2
18.0
3.87
0.19
This Project Summary was authored by John E. Matthews, who was also the
EPA Project Officer (see below).
The complete report, entitled "Evaluation of the Effectiveness of Granular
Activated Carbon Adsorption and Aquaculture for Removing Toxic Com-
pounds from Treated Petroleum Refinery Effluents," was authored by Sterling
L Burks of the Water Quality Research Laboratory, Oklahoma State University,
Stillwater, OK 74074.
The above report (Order No. PB 81-199 374; Cost: $8.00, 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
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
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