United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711 ""'/^f \^
Research and Development
EPA-600/S2-83-040 July 1983
&EPA Project Summary
Extraction of Pesticides from
Process Streams Using High
Volatility Solvents: A Feasibility
Study
S. L Reynolds
The objective of this research pro-
gram was to determine the feasibility
of extracting pesticides from process
streams using a liquid-liquid solvent
extraction approach.
A brief literature review was con-
ducted initially to provide foundational
data in support of the technology identi-
fied for study. The review resulted in a
bibliography organized by subject area
into four discrete categories consistent
with the project goals. Information
was acquired which enabled the priority-
ranking and subsequent selection of
pesticides for project study and the
identification of optimum solvents for
liquid-liquid extraction. A compilation
of various engineering design options
for liquid-liquid extraction systems led
to the selection of a design choice
consisting of a countercurrent flow,
rotary disc contactor (RDC) process.
Finally, literature on engineering pro-
cess economics enabled the formula-
tion of reliable cost estimates for the
derived technology.
Information from the literature review
and collaboration with EPA personnel
led to the selection of seven pesticides
and five solvents for study. These
pesticides and solvents were subjected
to comprehensive screening and ex-
traction to determine the partition co-
efficient (Kp) for each pesticide/sol-
vent combination. The screening/ex-
traction utilized a simple batch hand-
shakeout procedure and resulted in
favorable Kp values for a number of the
pesticides studied. The DDT, toxaphene,
and chlordane shakeout tests yielded
the highest extraction coefficients.
The generally favorable results of the
screening/extraction were considered
sufficient to warrant initiation of bench-
scale experimental studies. Partition
coefficients for the pesticide/solvent
mixtures studied are presented in this
report
Based on the literature review and
the screening/extraction, it was de-
termined that the optimum design
candidate for a liquid-liquid extraction
device consisted of an RDC Based on
this finding, S-Cubed elected to design
and fabricate a bench-scale RDC-type
system (the Solvent Extraction of
Organic Pesticides (SEXOP) system)
to be used to determine if the system
would be commercially feasible both
technically and economically whan
used on process streams. The SEXOP
system was used to test both synthetic
and real-world process effluent DDT
samples. Tests using the synthetic
sample demonstrated extraction effi-
ciencies in excess of 99.9%. Subse-
quent to process optimization, bench-
scale runs using real-world process
effluent DDT samples (consisting of
raw untreated waste) resulted in a
cleanup for most constituents in excess
of 99%. No constituents of the best-
case final run were extracted at an
efficiency level below 90%.
In light of the technical results of
SEXOP with synthetic and process
effluent DDT samples, an economic
analysis of the process was undertaken
to develop an economic basis for the
technology. Based on current know-
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ledge, an engineering cost estimate
was projected for both a large and a
small commercial-scale SEXOP process.
The derived estimates were then com-
pared to the more firmly established
capital and operational costs associated
with carbon adsorption technology.
This comparison revealed that the cost
of the SEXOP technology compares
favorably with the carbon adsorption
alternative.
This Project Summary was developed
by EPA's Industrial Environmental Re-
search Laboratory, Research Triangle
Park. NC, to announce key findings of
the research project that is fully doc-
umented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
This report describes work to explore
the feasibility of extraction of pesticides
from process streams using a liquid-liquid
solvent extraction approach. Research
conducted on the project addressed three
areas:
1. Solvent/pesticide partition coefficients
were established through use of both
synthetic pesticide mixtures and pesti-
cide manufacturing wastewaters.
2. A bench scale liquid-liquid extraction
unit was designed and fabricated, and
experimental studies were conducted
to test the capability of the system.
3. Subsequent to the bench scale runs,
economic feasibility studies were con-
ducted to determine the potential pro-
cess viability as compared to com-
mercial-scale carbon adsorption sys-
tems.
Research objectives in the above three
areas were met by work in four discrete
task areas: literature review, screening/
extraction studies, bench scale studies, and
an economic analysis.
Foundational concepts and supportive
data for work on this project were derived
from prior in-house S-Cubed supported
research into the feasibility of liquid-liquid
solvent extraction of pesticides from water.
Results and Conclusions
Summarized here are the results and
conclusions from the four general project
research objectives. These objectives in-
volved: a literature review; derivation of
partition coefficients for selected pesticides/
solvent/water systems; the design, fabri-
cation, and checkout of a bench-scale
extraction device; and determination of
the economic feasibility of the developed
solvent extraction technology. Conclusions
for each of these three project research
objectives are summarized separately
below.
Literature Review
A brief literature review established cur-
rent information on:
• Ranking of environmentally signifi-
cant pesticides.
• Candidate solvent systems appropri-
ate for liquid-liquid extraction.
•- Engineering design parameters for a
liquid-liquid extraction process.
• Economic considerations with re-
spect to solvent selection and process
design.
This literature review resulted in a bibliog-
raphy organized by subject area into the
above four categories The bibliography
also provides a brief abstract of each
citation.
Information acquired during the litera-
ture review provided strong foundational
data in support of the identified project
research objectives. These data enabled
the priority-ranking and subsequent selec-
tion of pesticides for project study and the
identification of candidate solvents for
liquid-liquid extraction. A compilation of
various engineering design options for
liquid-liquid extraction systems led to the
selection of a suitable design choice con-
sisting of a countercurrent-flow, rotary
disc contactor (RDC) process. Finally,
literature on engineering process economics
enabled the formulation of reliable cost
estimates for the derived technology.
Derivation of Partition
Coefficients
The literature review, in conjunction
with collaboration with EPA personnel, led
to the selection of the following pesticides
(the term pesticide in this report is used
generically to include both insecticides
and herbicides) and solvents:
• Pesticides
-DDT
- Chlordane
- Norflurazon
- Diuron
- Bromacil
- 2,4-D
- Glyphosate
• Solvents
- Hexane
- Pentane
- Isopropyl Ether
- Diethyl Ether
- Butyl Chloride
These pesticides and solvents were sub-
jected to detailed screening and extraction
to determine the partition coefficient (Kp)
for each pesticide/solvent combination.
The convention associated with the extract-
ability of a constituent from water stipulates
that a high Kp value strongly favors high
extraction efficiencies. The screening/
extraction during this phase of the project
(using a simple batch, hand-shakeout pro-
cedure) yielded favorable Kp values for a
number of the pesticides studied. The
DDT, toxaphene, and chlordane shakeout
tests resulted in the highest extraction
coefficients. The generally favorable re-
sults of the screening/extraction were
considered to be sufficient to warrant
initiation of the Task 3 bench scale studies.
Backup data in the report support this
conclusion.
Design, Fabrication, and
Checkout of a Bench-scale
Solvent Extraction Process
Based on the literature review and the
screening/extraction, it was determined
that the optimum design category for a
liquid-liquid extractor system belongs to a
group of process types called "Continuous
Differential Contactors." Within this design
group, the most highly favored option
consisted of an RDC. Based on this
finding, S-Cubed elected to design and
fabricate the bench-scale RDC-type solvent
extraction of organic pesticides (SEXOP)
system. Comprehensive discussion, pre-
senting both pictorial and narrative design
information, is presented in this report
The purpose of this bench-scale SEXOP
system was to test further that the system
would be commercially feasible both tech-
nically and economically when used on
process streams. A series of 10 studies
were conducted using both synthetic and
real-world process effluent DDT samples.
Studies using the synthetic samples re-
sulted in a cleanup(i.e., extraction efficien-
cy) in excess of 99.9%. Subsequent to
process optimization, bench-scale runs
using a real-world process effluent DDT
sample resulted in a cleanup for most
constituents in excess of 9996. No con-
stituents in the sample (of the best-case
final run) were extracted at an efficiency
level below 90%. Data supporting these
findings are presented in this report. It
should be stressed that the process ef-
fluent samples consisted of raw untreated
wastewater which gas chromatography/
mass spectrophotometry (GC/MS) analysis
revealed to contain at least 52 components.
Based on the high extraction efficiencies
resulting from the bench scale runs using
DDT, and the generally favorable extraction
coefficients for the pesticides examined
during the screening/extraction, it can be
concluded that SEXOP technology is po-
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tentially applicable to other constituents
with similar Kp values. An examination of
the detailed chemical composition of avail-
able in-house effluent samples shows that
many of the same constituents present in
the DDT sample are common to other
wastes as well. This would indicate a
broad-range applicability of SEXOP to a
variety of highly contaminated samples.
Economic Analysis
In light of the technical results of SEXOP
with the synthetic and process effluent DDT
samples, an economic analysis of the pro-
cess was undertaken to develop an eco-
nomic basis for the technology. This in-
volved a twofold approach: (1) based on
current knowledge, an engineering cost
estimate was projected for both a large and
a small commercial-scale SEXOP process;
and (2) these cost projections were com-
pared with the more firmly established
capital and operational costs associated
with carbon adsorption technology. This
study revealed that the cost of the SEXOP
technology compares favorably with the
carbon adsorption alternative. Current
state of the technology for SEXOP is such
that this determination must be viewed
with some latitude.
S. L Reynolds is with S-Cubed. La Jolla, CA 92038-1620.
Robert V. Hendriks is the EPA Project Officer (see below).
The complete report, entitled "Extraction of Pesticides from Process Streams
Using High Volatility Solvents: A Feasibility Study." (Order No. PB 83-209 767;
Cost: $16.00, 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:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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