United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
v>EPA
Research and Development
EPA-600/S2-80-077 Dec. 1 981
Project Summary
Treatability Studies of
Pesticide Manufacturing
Wastewaters
R. Zweidinger, E. Monnig, L. Little, R. Batten, D. Liverman, M. Warner, W.
Hendren, M. Murphy, and T. Wolff
Laboratory and pilot studies of the
treatability of pesticide manufacturing
wastewaters were conducted in a
project designed to investigate the
suitability of individual pesticide
manufacturing wastewaters for dis-
charge to biological treatment sys-
tems, whether publicly owned treat-
ment works (POTWs) or on-site sys-
tems. The pesticides studied were
carbaryl, dinoseb, atrazine, dazomet,
glyphosate, and an ethylenebisdithio-
carbamate fungicide.
The approach taken with each
pesticide manufacturing wastewater
was prioritized; that is, less costly,
more available methods of treatment
were investigated first. The preferred
method of treatment was assumed to
be biological. The suitability of the
pesticide wastewater for direct bio-
logical treatment was based on chemi-
cal and toxicological evaluation of the
waste after treatment. Where infor-
mation was available on actual dilution
rates upon entering biological treat-
ment facilities, these rates were used
in the evaluation. If the waste was
judged suitable for biological treat-
ment, additional treatment options
were not evaluated.
This Project Summary was developed
by EPA's Industrial Environmental
Research Laboratory, Research Tri-
angle Park, NC. to announce key
findings of the research project that is
fully documented in five separate
reports (see Project Report ordering
information at back).
Introduction
In Feburary 1979, Research Triangle
Institute (RTI) was requested by EPA's
Industrial Environmental Research
Laboratory, Research Triangle Park
(IERL-RTP), NC, to conduct laboratory
and pilot studies of the treatability of a
number of pesticide manufacturing
wastewaters. The project was designed
to investigate the suitability of individual
pesticide manufacturing wastewaters
for discharge to biological treatment
systems, whether publicly owned treat-
ment works (POTWs) or on-site systems.
Six pesticides were selected for study.
Their chemical structures are given in
Figure 1. Factors influencing selection
were:
(1) Potential for continued use of the
pesticide.
(2) Production of a significant liquid
waste stream.
(3) Large annual production and
widespread use.
(4) Chemical class; i.e., representa-
tives of several types of chemical
structures.
(5) Availability of the wastewater:
i.e., interest of the manufacturers
in cooperating with the study.
(6) Present treatment of wastewater;
i.e., wastewaters now deep-well-
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0
O-C-NH-CH3
Carbaryl
Dazomet
CH3
CH-CH2-CH3
HSC2-NH
,CH3
C-NH-CH
i
N
NO2
Dinoseb
0 0
II II
HO-C-CH2-NH-CH2-P-OH
I
OH
r
ci
Atrazine
[S-SC-NH-CH2CH2-NH-CS-S]* My
Where M is a transition metal or mixture
of transition metals
Glyphosate
Figure 1. Chemical structures of pesticides studied.
Ethylenebisdithiocarbamate
(EBDC) Fungicides
injected or contract-hauled were
considered because of the poten-
tial for groundwater contamina-
tion with present disposal meth-
ods.
Carbaryl is a wide-spectrum insecti-
cide for control of insects on cotton,
vegetables, fruit, rice, sugarcane, and
ornamentals. Atrazine is a registered
herbicide used for pre- and post-
emergence weed control on numerous
crops including corn, sorghum, sugar-
cane, and nursery conifers; it is recom-
mended1 for use in fish ponds for
selective control of farm pond weeds,
especially submerged aquatics. Dinoseb
is a general-contact weed killer for both
pre- and post-emergence control.
Glyphosate is a post-emergent herbicide
registered with the EPA for the control
of annual and perennial weeds before
the emergence of agronomic plants. It is
also effective in controlling ditch bank
vegetation. Maneb-type ethylenebis-
dithiocarbamate (EBDC) fungicides are
used to control foliar fungal blights. It is
recommended for prevention of early
and late blight on tomatoes and potatoes
and can be combined with other
fungicides for persistent fungal strains.
EBDC fungicides are used to control
over 400 fungal diseases for protection
of over 70 crops.
Treatability Studies
The approach taken with each pesti-
cide manufacturing wastewater was
hierarchical; that is, less costly, more
available methods of treatment were
investigated first. The preferred method
of treatment was assumed to be
biological. The manufacturing waste-
waters first were characterized for their
pesticide content and for routine
wastewater parameters, including
toxicity to fish, algae, and activated
sludge. They were then subjected to
bench-scale continuous activated sludge
(AS) treatment using the complete-mix
continuous-feed units designed by
Swisher (1970) and/or those designed
by the Organization of Economic Coop-
eration and Development (O.E.C.D.)
(Bundegesetzblatt, 1977). These units
are made entirely of glass, avoiding the
possibility of contamination by organics
leaching from the containers. Continu-
ous feed to the units was supplied
through Teflon tubing by a peristaltic
pump.
Routine determinations were made of
dissolved oxygen, pH, mixed liquor
volatile suspended solids in the aerator,
COD, and pesticides in the influent and
effluent. Dissolved oxygen was deter-
mined with an oxygen probe (Yellow
Springs Instrument Company).
If pesticide manufacturing wastewater
disrupted biological treatment systems,
despite gradual increase of concentra-
tion and acclimation, the possibility of
preheating the waste prior to biological
treatment was investigated. Pretreat-
ment included pH adjustments, filtration,
flocculation, and oxidation, depending
on the nature of the wastewater arid its
chemical composition.
If pretreatment did not improve! the
performance of activated sludge sys-
tems, adsorption techniques were
investigated, involving both carbon and
resin systems. Physical-chemical treat-
ability of wastewaters was then evalu-
ated again with the biological treatment
system (i.e., removal of toxicity arid of
constituents of interest).
Conclusions and
Recommendations
Carbaryl
Based on the results of the bench-
scale experimental work in this study,
both carbaryl manufacturing waste-
water, when mixed 1 part in 9 parts
municipal wastewater, and carbaryl
itself, when spiked at 10 mg/L in
municipal wastewater, appear suitable
for biological treatment by acclimated
systems if additional provision is made
for removing ammonia in the effluents
from the biological treatment system.
Other parameters investigated in this
study—including carbaryl, oc-naphthol,
and toluene concentrations—and chem-
ical oxygen demand (COD) showed large
reductions (90 percent or greater). The
mechanisms of reduction of these
parameters include combined hydrolysis
and biodegradation of carbaryl and °c-
naphthol, volatilization of toluene, and
biodegradation of species contributing
to COD.
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A large increase in ammonia concen-
tration was noted in the effluent from
the biological treatment units relative to
their influent. This ammonia concentra-
tion made the toxicological evaluation of
the effectiveness of treatment problem-
atic by rendering the effluent more toxic
than the influent. Ammonia stripping
lessened this toxicity. Because the
technology of nitrogen control has been
extensively developed, these treatment
options were not pursued further.
The carbaryl manufacturing waste-
stream investigated in this study is now
mixed with other manufacturing waste-
streams and treated in a manufacturer-
operated aerated lagoon with approxi-
mately a 3-day retention time. Based on
the study, this treatment process should
be adequate for the carbaryl manu-
facturing wastestream if there is no
interference from the components of
other wastestreams and if nitrification
of ammonia occurs.
Dinoseb and Atrazine
The effluent from the manufacture of
dinoseb and atrazine proved suitable for
a treatment system involving preliminary
activated carbon filtration to remove the
herbicide, followed by biological treat-
ment to reduce oxygen demand exerted
.by solvents and other organic com-
pounds. Several other treatment systems
were tried but were not successful.
These alternatives included biological
treatment of the manufacturing wastes
diluted in municipal wastewater. This
system provided some reduction in
chemical oxygen demand (COD) of the
waste. However, both the dinoseb and
the atrazine levels were unaffected.
A pretreatment system involving the
hydrolysis of pesticide manufacturing
wastes was tried. This system greatly
reduced the phytotoxicity of the wastes
as measured by the algal bioassay.
However, subsequent biological treat-
ment of this waste provided only a
marginal reduction in the hydroxyatra-
zine byproducts of the hydrolysis
reaction.
Activated carbon filtration alone
greatly reduced the phytotoxicity of the
pesticide manufacturing wastes. Sub-
stantial breakthrough of other organic
compounds (e.g., solvents such as
acetone) was seen before any break-
through of either of the pesticides from
the carbon column. This COD content
was then further reduced in a biological
treatment system through the mechan-
isms of volatilization and biological
degradation. Biological treatment re-
duced the phytotoxicity of these wastes
below that seen with activated carbon
treatment alone.
The volatile nature of the organic
constituent of this waste could allow
consideration of air-stripping as a viable
treatment option after carbon treatment.
Additional work would be necessary to
determine the effluent quality achievable
with air-stripping and the nature of the
stripped organics.
A report has been made of the
formation of nitrosamines in excess of
200 ppm in the formulation of dinoseb
as a diethanolamine salt (Bontoyan,
Law, and Wright, 1979). While the
formulation of dinoseb is not expected
to generate an aqueous wastestream,
care should be taken in any washup or
rinsing procedure after formulation.
Monitoring for various nitrosamines is
recommended if there is reason to
believe that there is a source of input of
these nitrosamines into the main plant
wastestream.
Dazomet
The effluent from the manufacture of
dazomet was tested for treatability by
activated sludge systems when diluted
1:100, 1:500, and 1:1000 in municipal
wastewater. At 1:100 dilutions, dazomet
concentrations showed over 95 percent
reduction after biological treatment.
However, effluent COD levels were
unacceptably high at an average of 160
mg/L. At 1:500 levels, the effluent COD
was much closer to the control effluent.
However, nitrification of ammonia was
severely hampered. At 1:1000dilutions,
the dazomet wastewater had a variable
effect on nitrification while effluent
COD levels were close to controls. It is
recommended that dazomet wastewater
be diluted to at least 1:1000 in municipal
wastewater to minimize the negative
effects on the nitrification of ammonia
during the activated sludge treatment
process.
No difference in toxicity in bioassay
tests was noted in effluents from
activated sludge units fed 1:500 or
1:1000 dilutions and units fed munici-
pal wastewaters alone.
Pretreatment of the dazomet waste-
water by air-stripping under alkaline
conditions (pH 11) reduced the dazomet
concentrations but had no effect on the
COD or ammonia concentration. Air-
stripping at low pH was not attempted
due to the generation of toxic carbon
disulfide under these conditions.
Glyphosate
Various combinations of glyphosate
production wastestreams were sub-
jected to biological treatment following
lime-pretreatment to reduce high levels
of glyphosate. Bench-scale biological
treatment demonstrated that glyphosate
did not appear to interfere with the
biological degradation process at con-
centrations up to 105 mg/L. On the
other hand, glyphosate itself showed
only partial reduction with biological
treatment (28 to 45 percent). The
mechanism of this removal is not fully
understood but may include sorption to
sludge. No evidence for metabolism of
glyphosate was generated in oxygen
uptake studies. While the test does not
provide any evidence for metabolic
uptake of glyphosate, it is also inter-
esting that fairly high concentrations of
the compound do not inhibit other
microbial processes in acclimated
sludge.
Biological treatment significantly
reduced the toxicity of these effluents.
Test data clearly show that the higher
toxicity in influents versus effluents is
not due to glyphosate itself but to other
wastestream components, many of
which are "effectively treated in an
activated sludge process. The toxicity of
glyphosate was found to depend on
water quality parameters such as
calcium and magnesium concentration;
toxicity decreased as water hardness
increased. Glyphosate was more toxic
in soft water than similar concentrations
of glyphosate in the effluents from
biological treatment systems. The
decreased toxicity in effluents is probably
related to the addition of calcium in the
lime pretreatment step.
Additional treatment options were
investigated in an attempt to reduce
glyphosate concentrations in the in-
fluents to biological treatment. These
options, including ozonation, adsorption,
and ion exchange, provided only mar-
ginal reduction of glyphosate.
Ethylenebisdithiocarbamate
(EBDC) Fungicides
At levels representative of their
concentration in the influent to the
POTWs, neither the wastewater from
the EBDC production unit nor the total
plant wastewater affected the ability of
pilot activated sludge units to remove
COD. At these levels, the presence of
both wastewaters strongly inhibited
nitrification in activated sludge units, as
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compared to control units fed typical
domestic wastewater alone.
Biological treatment decreased, but
failed to eliminate, the amount of
ethylenethiourea (ETU), a decomposition
product of the pesticide, in the waste-
waters. Nitrification and ETU removal
were superior in activated sludge units
inoculated with sludge from a plant
treating domestic wastewater, compared
to units inoculated with sludge from the
POTW receiving the pesticide waste-
water. Nitrifying bacteria are known to
be inhibited by thioureas. These findings
possibly indicate that continued expo-
sure of sludge to the EBDC wastewaters
can reduce the bacterial populations
responsible for nitrification and for ETU
removal.
Results of bioassays in the two
wastewaters showed inhibition of
growth and mobility characteristics.
Metals analysis indicated that this
toxicity could be due in part to the
presence of Mn and Zn. If so, removal of
these metals might be investigated as a
means of relieving the toxicity of the
wastewaters to aquatic organisms.
Note, however, that at dilutions repre-
sentative of actual conditions at the
receiving POTW neither wastewater
exhibited much toxicity.
Future studies should be conducted to
define the effects of ETU and EBDC
fungicides on nitrification, since this
process, either in a POTW or in a
receiving stream, is critical to mainten-
ance of the nitrogen cycle. The public
health significance of ETU in the
activated sludge effluents should also
be investigated.
References
Bontoyan, W. R., M. W. Law, and D. P.
Wright, Jr., Nitrosamines in Agricul-
tural and Home Use Pesticides. Jr.
Agr. Food Chem.,.27(13):631-635,
1979.
Bundegesetzblatt, Jahrgang. 1977, Teil
1,p. 245.
Swisher, R. D., Surfactant Biodegrada-
tion. Marcel Dekker, Inc., N.Y., 1970.
R. Zweidinger, E. Monnig, L Little. R. Batten, D. Liverman. M. Warner, W.
Hendren, M. Murphy, and T. Wolff are with Research Triangle Institute, P. O.
Box 12194, Research Triangle Park, NC 27709.
David C. Sanchez is the EPA Project Officer (see below).
The complete report consists of five volumes, entitled "Treatability Studies of
Pesticide Manufacturing Wastewaters":
Carbaryl (Order No. PB 80-224 306; Cost: $6.50, subject to change)
Dazomet (Order No. PB 81-129 033; Cost: $6.50, subject to change)
Dinoseb and Atrazine (Order No. PB 81-178 840; Cost: $6.50, subject to
change)
Glyphosate (Order No. PB 81-159 097; Cost: $8.00, subject to change)
Ethylenebisdithiocarbamate Fungicides (Order No. PB 82-107 566; Cost:
$9.50, 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:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
it US GOVERNMENT PRINTING OFFICE, 1981 — 599-017/7408
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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Penalty for Private Use $300
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