United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/009 June 1987
SEPA Project Summary
Field Assessment of Aerated
Lagoon Emissions and Their
Control Using an Inflated Dome
Thomas P. Nelson, Bart M. Eklund, and Robert G. Wetherold
The fate of volatile organic
compounds (VOC") in an industrial
wastewater activated sludge system
was investigated through a four-day
sampling and analysis program. The
system included an aerated lagoon
which is covered by an Inflated
synthetic dome. The dome has a
carbon adsorption column to reduce
emissions of odorous organic
compounds. Samples of air, water
and sludge streams associated with
the activated sludge system were
collected, along with air samples at
the inlet and outlet of the carbon
adsorber. These were analyzed to
determine the concentrations of
individual volatile organic
constituents. The effectiveness of
the dome and carbon adsorber in
reducing lagoon emissions of volatile
organic compounds was
investigated, as was the applicability
of the Thibodeaux-Parker-Heck
model to predicting emissions from
the covered aerated lagoon.
Approximate percentages of removal
of VOCs by biodegradation,
adsorption and volatilization in the
aerated lagoon were determined.
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
As used in this study the term
volatile organic compound (VOC)
applies to compounds which can be
extracted from liquid wastes by a
purge and trap method
report of the same title (see Project
Report ordering information at back).
Introduction
The Office of Air Quality Planning and
Standards (OAQPS) of the U.S.
Environmental Protection Agency is
developing standards to control
emissions from hazardous waste
treatment, storage, and disposal facilities
(TSDFs). The purpose of these
regulations is to protect human health
and the environment from impairment by
emissions of volatile organic compounds
(VOCs) and particulate matter. The
Hazardous Waste Engineering Research
Laboratory (HWERL) has the
responsibility of providing technical
support to OAQPS in the area of
atmospheric emissions from hazardous
waste management. Part of the research
in the HWERL program involves studying
emission control techniques applicable to
TSDFs.
The objective of this project was to
obtain field measurements of the
effectiveness of emission controls for
off-gases from an aerated lagoon.
Specifically, the three primary objectives
of the lagoon enclosure testing were to:
• measure the control efficiency of the
activated carbon beds which were used
in the treatment of the off-gases from
the lagoon;
• measure the overall effectiveness of
the dome and carbon adsorption
system in controlling lagoon emissions;
and
• determine the applicability of
Thibodeaux's model to predicting
emission rates from aerated
impoundments.
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As part of the assessment of lagoon
emissions and their control, an
approximate mass balance was
performed around the lagoon to
determine the fate of influent VOCs. Also,
the effectiveness of 55 gallon drums of
carbon used to control breathing and
working losses in the waste pretreatment
area was determined.
The TSDF site chosen for this study is
the Upjohn Fine Chemicals facility in
North Haven, Connecticut. At this facility
Upjohn produces speciality chemicals as
intermediates for other Upjohn divisions
and for sale to other end users. At the
time of this sampling, 1984, the
wastewater was being treated in a series
of processess (naturalization, primary
clarification, and activated sludge) prior
to being discharged (see Figure 1).
The site was chosen because of the
emissions control system used at Upjohn
to minimize odor.This system is located
at the aerated lagoon that is part of the
activated sludge system. Control
consists of an inflated dome over the
lagoon with carbon adsorption beds to
remove odorous compounds (primarily
orthochlorophenol) from the exhaust
gases (Figure 2). While ortho-
chlorophenol is very water soluble, but
not highly volatile, the facility
wastewaters do contain aromatic and
halogenated organic compounds which
are volatile. The dome and carbon
adsorption system at Upjohn was studied
to determine its efficiency in controlling
emissions of these volatile compounds.
Approach
The nonmethane hydrocarbon
(NMHC) content of the dome bleed-off
gas was monitored at the inlet and outlet
to the dome's carbon adsorption unit and
inside the dome using on-site total
hydrocarbon and gas speciation
instrumentation. Canister samples were
collected for gas specification off-site.
Samples were also collected at the inlet
and outlet of 55 gallon drum carbon
adsorption units at the vents to the
wastewater treatment system neutralizer
tank. A screening of potential leak points
around the dome was performed using a
portable hydrocarbon analyzer.
Liquid and sludge samples were
collected at selected points around the
wastewater treatment system. These
were analyzed for total NMHC content
and for major volatile organic species.
The resulting data were used
determine the fate of volatile organi
entering the aerated lagoon.
The composition data of the aerati
lagoon effluent were utilized in tl
Thibodeaux-Parker Hwang emissioi
model for aerated surface impoundmer
to predict emissions with the dome
place.
Findings
The volatile organics identified in tl
influent stream to the aerated lagoi
were classified as volatile paraffii
(15%), aromatics (45%), and haloge
(40%). Major volatile compounds inclui
1,2-dichloroethane, benzene, toluei
and chlorobenzene. The approxima
material balance performed around tl
aerated lagoon indicated th
approximately 60 weight percent (± 201
of the influent VOCs are volatilized ai
exhausted from the dome structure. Tl
volatilized organics are primari
halogenated organic compounc
(e.g.,1,2-dichloroethane). Twenty-eig
percent (±4%) of the influent VOCs a
discharged from the aerated lagoo
These are predominately paraffins.
Sludge Sludge
Clarifier
Underflow
Centrifuges
FM
Caustic
Clarifier
Underflow
Carbon
Cannisters
Process
Wastewater
Aerated Lagoon/
Dome Structure
Clarifier (F-M
Underflow
(ff/
I
FM
Secondary
Clariliers
Clarifier
Overflow
-(FM
-^ To Municipal
Wastewater Syste
(Not Operating)
Wastes
to River
Figure 1. Wastewater treatment system.
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Main Blower
(Capable of up to
20.000 CFM @ 1.5 W.CJ*
NE Comer
of Dome
Dome
Concrete
Footing
Carbon Adsorber
Fan (3OOO CFM)
Doorway
with Blower
(Under Positive
Pressure with
Respect to
Bubble Pressure)
Auxiliary
Blower
(Propane-
Powered)
Propane Heater
for Winter Operation
(Capable of 2,500,000 Btu/hr)
(Open) (Closed)
Outside Air
Intake Dampers
*Has been shimmed and current air flow rate is unknown.
Figure 2. Dome structure inflation fan and exhaust system.
Due to the combined uncertainties in
measured influent, effluent and emission
rates, a large uncertainty was associated
with estimating VOC biodegradation by
difference. Biodegradation was the major
pathway for aromatics removal,
accounting for 65 percent (±20%) of
aromatic fate. However, the amounts of
paraffins and halogenated VOCs that
were removed by biodegradation were
smaller than the combined uncertainties
of the measurements used to estimate
them.
The Monte Carlo simulation
uncertainty analysis performed on the
material balances showed two
weaknesses in the determination of the
fate of organic compounds in the aerated
lagoon. First, difficulties with the
extraction of volatile organics from
wastewater sludge streams led to an
uncertainty of ±50% in their VOC
content. Second, there was a large
uncertainty (up to ±58%) in emissions
measurements due to the variability in
gas composition going through the
carbon adsorber.
The inflated dome is estimated by the
facility to have less than a 0.14 m3/sec
(300 cfm) leakage rate, which is low
compared to the purge gas bleed-off
rate of 1.4 m3/s (3000 cfm). A
preliminary screening of the dome
structure indicated that the largest leaks
were small in number and had very low
(<1 x 10-4 m3/s) flow rates.
The carbon adsorber on the dome
exhaust provides virtually no (<1%)
VOC removal. This is primarily because
the extremely high (approximately 100
percent) relative humidity in the carbon
adsorber inlet gas stream is believed to
interfere with the adsorption capability of
the carbon. The activated carbon bed
system was originally designed for
control of water soluble odorous
compounds, and Upjohn feels that the
system is performing this function
effectively.
Fifty-five gallon drums of activated
carbon are used on vented emissions
from the neutralizer tanks and primary
clarifier at the TSDF. Testing indicated
that these drums work very well in
removing NMHC emissions in the vent
gas. Removals of over 99 percent were
measured for specific hydrocarbon
compounds.
Mathematical models developed by
Thibodeaux-Parker-Heck models are
inconsistent in their abilities to predict
actual emission rates. Comparability of
modeled and measured emission rates
varied with compound. This appeared to
be partially due to a significant
concentration of VOCs in the dome
atmosphere and due to the shallowness
of the lagoon, which may have inhibited
complete mixing of wastewater and led to
nonuniform VOC concentrations within
the lagoon. Also, the inability to
empirically determine key model
variables limits the accuracy of the
models.
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Thomas P. Nelson, Bart M. Eklund, and Robert G. Wetherold are with Radian
Corporation, Austin, TX 78766.
Benjamin L Blaney is the EPA Project Officer (see below).
The complete report, entitled "Field Assessment of Aerated Lagoon Emissions
and Their Control Using an Inflated Dome," (Order No. PB 87-145 9421 AS;
Cost: $24.95, 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:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-87/009
0000329 PS
U S EHVIR PROTECTION AGENCY
REGION 5 LIBRARY
230 S DEARBORN STREET
CHICAGO IL 60604
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