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(1.
SEPA
United States
Environmental Protection
Agency
EPA/540/MR-92/018
July 1992
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Treatability Study Bulletin
Enzyme-Activated Cellulose Technology
Thorneco, Inc.
Technology Description: The Enzyme-Activated Cellulose
Technology developed by Thorneco, Inc. uses cellulose placed
into one or more cylindrical towers to remove metals and organic
compounds from an aqueous solution. The cellulose is coated
with a proprietary enzyme. Operating parameters that can affect
the process efficiency include flow rate, cellulose dosage, enzyme
solution, and pH.
A schematic of the Thorneco treatment process is shown in
Figure 1. Following enzyme treatment, the cellulose is placed into
one or more cylindrical towers that operate in series. Contaminated
water enters the tower from the bottom and flows upward through
the enzyme-activated cellulose to the discharge pipe located at
the top of the tower.
Waste Applicability: This treatment technology is directed at
the removal of metals and organic compounds from an aqueous
solution in the form of ions, particulates or colloidal compounds.
Enzyme-activated
cellulose loaded
from top,
Flow
Sampling point
Sampling point 3
Sampling point 4
Discharge
Figure 1. Thorneco enzyme—Activated cellulose technology—3tower
system.
Treatability Study Results: Key findings from the Thorneco,
Inc. treatability study are summarized as follows:
A strong trend could not be established for volatile
organic compound (VOC) removal in relation to pH and
cellulose dosage. The results for other contaminants
showed that generally higher pH levels resulted in better
removal.
Biological activity was not enhanced by the treated cel-
lulose in this study.
Freundlich and Langmuir (linear and non-linear) iso-
therm models were inadequate to represent concentra-
tion data obtained during the 48-hr batch contact ex-
periments. Therefore, the adsorption removal mecha-
nism could not be fully evaluated and the capacity and
lower limits of treatment of the cellulose could not be
determined.
• Removal of volatile organic compounds was primarily
the result of volatilization. The treated cellulose was
capable of increasing volatile organic compound re-
moval, on the average, by 10% to 31%, but the exact
removal mechanisms were not determined.
• Metals and nitrate removals were enhanced by the
treated cellulose. Precipitation appeared to be the pri-
mary removal mechanism for metals. The removal
mechanism for nitrate was not determined.
Phenols removal was very limited and was not consis-
tently enhanced by the treated cellulose.
Voluminous solids residuals produced from this study
required incineration at a hazardous waste incineration
facility due to the concentration of chlorinated hydrocar-
bons. Costs associated with waste disposal were not
analyzed because the amount of solids generated by
the process was not a component of the study.
Treatability Study Approach: The Thorneco, Inc. technology
was selected by EPA as a candidate technology for the Super-
fund Innovative Technology Evaluation (SITE) program. Due to a
lack of complete background data and uncertainty concerning the
technology's removal mechanism(s), a bench-scale treatability
study of the process was proposed.
The treatability study was conducted at the Engineering Science
(ES) treatability laboratory in Atlanta, GA. Experiments were
conducted between August 26, 1991 and September 30, 1991.
Contaminated groundwater for the study was obtained from Stream
A of the Stringfellow Superfund site in Glen Avon, CA.
OS) Printed on Recycled Paper
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The specific objectives of the study were to:
estimate the removal capacity and treatability limits of
the Thorneco process for individual pollutants in the
Stringfellow groundwater
determine the appropriate operating conditions (pH and
loading) for effective treatment of Stringfellow ground-
water by the Thorneco process
characterize the residuals from the process and discuss
their disposal requirements
evaluate the suspected removal mechanisms (exchange/
sorption, biodegradation and volatilization) in the
Thorneco process.
Prior to the study, the primary potential mechanisms for contami-
nant removal were identified to be volatilization, biodegradation
and/or adsorption. Adsorption was considered the most likely
removal mechanism based on information provided by the devel-
oper.
A series of preliminary screening experiments were conducted to
determine the most effective operating pH and cellulose dosage
for the subsequent 48-hr batch contact study and to evaluate
suspected biodegradation and volatilization removal mechanisms.
Mass loadings of 0.5-, 4-, and 20-gram treated cellulose per liter
were investigated at four pH values; as received (which ranged
from 3.3 - 3.56), and approximately 5, 7 and 9. An optimum pH
and cellulose dosage could not be established from the data
obtained from the screening experiments.
Based on the results of a follow-up pH/dosage study, the 48-hr
batch contact tests, including one control and two tests, were
conducted with cellulose dosages in the range of 80 to 180 g/L
and on groundwater at an "as-received" pH in order to study the
adsorption mechanism and the effectiveness of the treated cellu-
lose. The control experiment was conducted using untreated
cellulose and the two test experiments were conducted using
enzyme-treated cellulose.
All contact experiments were conducted in 1-gal, high density
polyethylene (HOPE) containers. The containers were placed into
a tumbler with a 10-container capacity. The tumbling time for the
screening experiments was 24 hr. After tumbling, the samples
were settled and then pressure-filtered and placed into the appro-
priate bottleware for analysis. The tumbling time for the 48-hr
batch contact tests was 48 hr. After tumbling, the contactors were
placed in a 4 °C refrigerator to facilitate settling of solids.
Although the Thorneco technology operates in a packed tower
configuration, batch contact experiments were chosen for the
study in order to obtain basic information about the adsorptive
capacity, stimulation of biological activity, and overall effective-
ness in removing selected contaminants for the treated cellulose
in a cost-effective manner.
The waste characteristics of the treatability samples were deter-
mined by collecting initial samples for VOCs prior to contact
experiments. Initial samples for all other parameters were col-
lected from contactors that did not contain cellulose, but were
tumbled, settled and filtered. Table 1 presents the range of
detectable contaminants that were found in the initial stream A
groundwater samples collected from Stringfellow during the treat-
ability study. A summary of the maximum percentage removals
for 48-hr batch contact experiments are given in Table 2.
Sampling and analyses were conducted for three sets of prelimi-
nary screening experiments (Operation Conditions Assessment,
Assessment of Biological Activity and Volatilization Losses) and
the 48-hr batch contact experiments (one control and two test
cases). A total of 13 aqueous samples were collected for the
Table 1. Concentration Ranges for Stream A Groundwater
Parameter
Chlorobenzene
Chloroform
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Dichloromethane
Trichloroethylene
Reporting
Unit
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
Concentration
Range
160-480
400-600
<100-430
<10-110
<500-1,600
1.000-2,200
Toluene ug/l
2-Chlorophenol ug/l
4-Chloro-3-Methylphenol ug/l
2,4-Dichlorophenol ug/l
2,4-Dinitrophenol ug/l
2,4-Dimethylphenol ug/l
2-Nitrophenol ug/l
4-Nitrophenol ug/l
Pentachlorophenol ug/l
Phenol ug/l
Cadmium mg/l
Chromium mg/l
Lead mg/l
Nitrate mg/l
Total Organic Carbon mg/l
Total Dissolved Solids mg/l
Total Suspended Solids mg/l
<10-76
55-89
<10-44
<10-46
<200-260
<10-90
<10-100
160-740
<100-160
87-200
1.9-2.3
75-99
<0.10-0.28
53-67
1,200-1,300
27,000-28,000
<4-12
Operating Conditions Assessment experiment; 17 aqueous
samples were collected from the aerobic and anaerobic biological
studies; and 24 aqueous samples and 3 solid residue samples
were collected during the 48-hr batch contact experiments. Aque-
ous samples were collected from the filtration apparatus for the
volatilization loss experiment.
For Further Information:
EPA Project Manager:
Teri L. Shearer
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7949
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Table 2. Summary of Maximum Percentage Removals for 48-hr Isotherm Experiments
Compound
Control
Cellulose
Dosage(s)
(g/L) Test 1
Cellulose
Dosage(s)
Test 2
Cellulose
Dosage(s)
(9/L)
Volatile Halogenated Organics
Chlorobenzene 85 (120) 75 (100,180) 95" (180)
Chloroform 63 (80) 81 (140) 78 (180)
Dichloromethane 58 (120) 83" (80) U
Trichloroethylene 78 (120) 95 (120) 98 (180)
Benzene ND ND U
Range 58-85 75-95 78-98
Phenols
2-Chlorophenol 88" (110) U 88" (140180)
4-Chloro-3-Methylphenol 77* (100,110) U U
2,4-Dinitrophenol ND 13" (100,110,120) U
2-Methyl-4,6-Dinitrophenol ND ND U
2-Nitrophenol 90" (80-110) U ND
4-Nitrophenol 83" (110) 86" (100-120) 72 (80-180)
Phenol 94" (80,100) 95" (100-120) 92" (80,100,160)
Range 77-94 13-95 72-92
Metals
Cadmium
Chromium
Lead
Range
Nitrate
Range
14
22
ND
14-22
13
0-13
(140)
(140)
(125)
79
88
U
79-88
84'
81-84
(80)
(80)
(80-160)
58
57
U
57-58
85"
68-85
(80,110)
(180)
(100,110,140,180)
"Percent removals computed using ND as equal to concentration at the detection limit.
ND - Not detected in any samples.
U - Unknown percent removal because concentration in initial sample was below detection limit.
•U.S. Government Printing Office: 1992— 648-080/60038
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