slEPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EMB Report 86—CEP-4
August 1986
Air
Chromium
Electroplating
Emission Test
Report
Piedmont
Industrial Plating
Statesville,
North Carolina
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EMISSION TEST REPORT
PIEDMONT INDUSTRIAL PLATING COMPANY
STATESVILLE, NORTH CAROLINA
ESED 85/02
EMB NO. 86-CEP-04
Prepared by
ENTROPY ENVIRONMENTALISTS. INC.
P. 0. Box 12291
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27709
CONTRACT NO. 68-02-4336
WORK ASSIGNMENT NO. 5
PN: 3505
EPA TASK MANAGER
DENNIS HOLZSCHUH
U. S. ENVIRONMENTAL PROTECTION AGENCY
EMISSION MEASUREMENT BRANCH
EMISSION STANDARDS AND ENGINEERING DIVISION
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
AUGUST 1986
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TABLE OF CONTENTS
Page
Figures iv
Tables v
1.0 INTRODUCTION 1-1
2.0 PROCESS OPERATION 2-1
2.1 Process Description 2-1
2.2 Air Pollution Control 2-2
2.3 Process Conditions During Testing , 2-4
3.0 SUMMARY OF RESULTS 3-1
3.1 Hexavalent Chromium and Total Chromium 3-3
3.1.1 Scrubber Inlet 3-3
3.1.2 Scrubber Outlet 3-5
3.2 Emissions in Units of Process Rate and Control Equipment 3-11
Collection Efficiency
3-2.1 Emissions in Units of Process Rate 3-11
3.2.2 Control Equipment Collection Efficiency 3-11
3-3 Analysis of Chrome Plating Solutions and Scrubber Liquor 3"H
3.4 Analysis for Chromium In Impinger Samples 3-13
3.5 Summary of Evaluations and Results for Screening Method
Testing 3-15
3.5.1 Detector Tubes 3-18
3.5.2 Filter and Personnel Pump Train 3-23
3.5.3 Impinger and Personnel Pump Train 3-23
4.0 SAMPLING LOCATIONS AND TEST METHODS 4-1
4.1 Scrubber Inlet (Sampling Location A) 4-1
4.2 Scrubber Outlet (Sampling Location B) 4-5
4.3 Scrubber Recirculation Water Reservoir (Sampling Location C) 4-5
4.4 Plating Tank Solutions (Sampling Locations D and E) 4-5
4.5 Velocity and Temperature 4-5
4.6 Molecular Weight 4-7
4.7 Sampling Trains 4-7
4.8 Hexavalent Chromium Content 4-8
4.9 Trivalent Chromium Content 4-8
5.0 QUALITY ASSURANCE 5-1
11
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TABLE OF CONTENTS (continued)
Page
APPENDICES
A TEST RESULTS AND EXAMPLE CALCULATIONS A-l
Hexavalent Chromium and Total Chromium A-3
Example Calculations A-9
B FIELD AND ANALYTICAL DATA B-l
Chromium Field Data B-3
Screening Method Field Data B-34
Chromium Sample Inventory B-82
Moisture Catch Analysis B-85
Hexavalent and ICP Chromium Analysis B-90
C SAMPLING AND ANALYTICAL PROCEDURES C-l
Determination of Hexavalent Chromium Emissions C~3
Determination of Trivalent Chromium Content C-14
U. S. EPA Memorandum: Detector Tube Testing at Piedmont C-17
Industrial Platers in Statesville, N.C.
D CALIBRATION AND QUALITY ASSURANCE DATA D-l
E TEST PARTICIPANTS AND OBSERVERS E-l
111
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FIGURES
Number Page
2-1 Schematic of Piedmont Industrial Plating hard chromium 2-7
plating operation.
2-2 Diagram of Duall F-101 horizontal-flow single packed-bed 2-8
fume scrubber.
3-1 Ranges for measurements of hexavalent chromium emissions 3~8
conducted at four scrubber water chromic acid concentrations
for mass emission rate, concentration, and emission rates in
units of process rate.
4-1 Schematic of Air Flow and Sampling Locations. 4-2
4-2 Piedmont Industrial Plating Company: Scrubber Inlet. 4-4
4-3 Piedmont Industrial Plating Company: Scrubber Outlet. 4-6
4-4 Mist Eliminator Outlet Stack (Test Location B). 4-7
4-5 Exhaust Duct on No. 5 Plating Tank (Methods Development 4-9
Test Location E).
C.I Method 13-Type Impinger Train. C-4
C.2 Andersen Mark III Cascade Impactor Loading Sequence. C-23
C.3 Sample Splits for Train #2. C-26
iv
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TABLES
Number Page
2.1 Dimensions and Operating Parameters of Hard Chromium Plating 2-9
Tanks at Piedmont Industrial Plating
2.2 Average Scrubber Water Chromic Acid Concentrations for Each
Test Run 2-10
2.3 Average Operating Parameters Recorded During Each Mass 2-11
Emission Source Test Run
2.4 Total Current Supplied to the Tanks During Each Mass Emission 2-13
Test Run
3.1 Testing Schedule for Piedmont Industrial Plating 3-2
3.2 Summary of Flue Gas Conditions 3-4
3.3 Summary of Hexavalent Chromium and Total Chromium Emissions 3-6
3.4 Summary of Emission Rates in Units of Process Rate and 3-12
Efficiency
3-5 Summary of Plating Solution and Scrubber Recirculating Water 3-14
Chromic Acid Concentrations
3.6 Analytical Results for Chromium Concentration in Large and 3~15
Small Plating Tank Grab Samples
3.7 Analytical Results for Chromium Concentration in Scrubber 3-16
Recirculating Water Grab Samples
3.8 Analytical Results for Hexavalent and Trivalent Chromium 3-1?
Chromium in Impinger Trains
3-9 Analytical Results for Hexavalent and Trivalent Chromium in 3~19
Screening Method Samples
3.10 Summary of Sampling Parameters and Chromium Emission Results 3-20
Screening Methods
3.11 Comparison of Impinger Train and Screening Method Results 3-21
3.12 Comparison of Chromium Catch on Filter vs. in Probe Rinse 3-24
4.1 Sampling Plan for Piedmont Industrial Plating Company 4-3
5.1 Field Equipment Calibration 5-2
5.2 Audit Report Chromium Analysis 5-4
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1.0 INTRODUCTION
During the week of August 18, 1986, Entropy Environmentalists, Inc.
conducted an emissions measurement program at Piedmont Industrial Plating
Company located in Statesville, North Carolina. The purpose of this program
was to evaluate the effect of scrubber water chromic acid concentration on
scrubber performance. The data may also be used to support a possible standard
for chromium emissions under the National Emissions Standards for Hazardous Air
Pollutants (NESHAPS).
The hard plating process at Piedmont Industrial Plating involves two hard
chromium plating tanks that share the use of one emissions control scrubber.
Comprehensive testing was conducted at the inlet and the outlet of this control
device. This source was selected for source sampling for the following
reasons:
• The plant is representative of a small-sized job shop that
performs hard chromium electroplating. Hard chromium plating is
applied to textile machine parts, industrial rolls, and tubing.
Based on operating parameters such as current, voltage, plating
time, and chromic acid concentration, the plating tanks selected
for testing appear to be typical of other hard chromium plating
tanks in the electroplating industry.
• The combined surface area of the two tanks in operation during
testing is large. They have equal width and depth dimensions of
0.9 meters [m] [3 feet (ft)] wide, and 1.2 m [4 ft] deep. The
larger tank is 7.0 m [23 ft] long, and the smaller is 3 m [10 ft]
long. A substantial amount of chromic acid mist is evident
across the entire surface of the plating baths when they are
operated at full capacity. Neither chemical fume suppressants
nor plastic balls are used in the plating bath to control
misting. These factors will ensure an adequate emission sample
to characterize uncontrolled emissions and the performance of the
scrubber.
• Both tanks are equipped with double-sided draft hoods that appear
to be very effective in directing fumes from the plating tanks to
the control device. No visible emissions or fumes were observed
escaping the capture systems of either tank during operation.
1-1
-------
Hexavalent chromium and total chromium concentrations were measured at the
scrubber inlet and outlet. The concentrations of the scrubber recirculation
water and of the plating tank solutions were also measured. The chromium
concentration of the scrubber recirculation water was increased over the test
program to determine the effect that the scrubber wat«;r chromium concentration
has on the performance capability of packed-bed scrubbers to control chromium
emissions. The data will be used as part of the technical basis for developing
a regulatory alternative based on the use of packed-bed scrubbers for removing
hexavalent chromium from ventilation air at hard chromium plating facilities.
Additional testing was conducted concurrent with Method 13-type impinger train
testing to determine the applicability of available detector tubes and personnel
monitoring equipment as a screening method for chromium emissions.
The emissions testing was performed using U. S. Environmental Protection
Agency (EPA) Reference Method 5 procedures and a Method 13-type impinger train*,
and the alternative sample preparation and analytical procedures described in
Appendix C. Flue gas flow rates, temperature, and moisture content were also
measured in conjunction with the chromium testing.
Mr. Randy Strait [Midwest Research Institute (MRI)] monitored process
operations throughout the test period. Mr. Dennis Holzschuh (EPA Task Manager
of the Emissions Measurement Branch (EMB) and Mr. Al Vervaert of the Industrial
Studies Branch (ISB) observed the test program. Mr. Robert Miller (Manager)
served as the contact for Piedmont Industrial Plating Company.
This report is organized into several sections addressing various aspects of
the testing program. Immediately following this introduction is the "Process
Operation" section which includes a description of the process and control
device tested. Following this is the "Summary of Results" section which
presents table summaries of the test data and discuss&s these results. The next
section, "Sampling Locations and Test Methods" describes and illustrates the
sampling locations used for emissions testing and then explains the sampling
strategies used. The final section, "Quality Assurance," notes the procedures
used to ensure the integrity of the sampling program. The Appendices present
the Test Results and Example Calculations (Appendix A); Field and Analytical
*43 Federal Register 11984, 3/23/78 (Method 5) and 43 Federal Register 4l852,
6/20/80 (Method 13).
1-2
-------
Data (Appendix B); Sampling and Analytical Procedures (Appendix C); Calibration
and Quality Assurance Data (Appendix D); MRI Process Data (Appendix E); and Test
Participants and Observers (Appendix F).
1-3
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2.0 PROCESS OPERATION
2.1 PROCESS DESCRIPTION
The Piedmont Industrial Plating plant In Statesville, North Carolina,
1s a job shop that performs hard chromium electroplating of industrial
machine parts, Industrial rolls, and steel tubing. The plating facility
is operated 15 hours per day, 5 days per week, and 50 weeks per year. The
facility consists of three plating tanks arranged as shown in
Figure 2-1.
All three tanks are typical of other hard chromium plating tanks used
in the electroplating industry with regard to size; operating parameters
such as current, voltage, and plating time; and chromic acid concentration
of the plating bath. During the source test program, only the 23-foot and
10-foot tanks were operated. The chromic acid consumption for the two
tanks is about 136 kilograms (300 pounds) per month. The dimensions and
operating parameters for these two tanks are presented in Table 2-1.
The 23-foot tank is used to plate long industrial rolls and tubing as
well as smaller parts. The tank is equipped with one 6,000- and three
1,000-ampere rectifiers. When industrial rolls or tubing are plated, the
6,000-ampere rectifier is used, and when smaller arid different kinds of
parts are plated, up to four work stations can be siet up in the tank.
Three of the work stations are charged with the 1,000-ampere rectifiers,
and one work station is charged with the 6,000-ampere rectifier. The
10-foot tank contains up to five work stations, each of which is charged
with a separate 1,000-ampere rectifier. During this source test program,
the 23-foot and 10-foot tanks were divided into two and five work
stations, respectively.
The plating solution used in the tanks is a conventional hard
chromium plating solution containing about 240 grams per liter (g/a)
(32 ounces per gallon [oz/gal]) of chromic acid and about 2.40 g/n
(0.32 oz/gal) of sulfuric acid.
One porous pot made of ceramic was used at work station 7 In the
23-foot tank during six test runs and at work station 1 in the 10-foot
tank during four test runs to reduce trivalent chromium contamination of
the plating solution. The concentration of trivalent chromium ions
2-1
-------
Increases to levels that contaminate the plating baths when the surface
area of the cathodes plated Is substantially larger than the surface area
of the anodes. The pots are made of ceramic that contains pores ranging
from 0.5 to 1.0 micrometer (0.002 to 0.004 mils) in diameter. Several
anodes are placed around the outside and a cathode is placed inside each
pot. The anodes and cathode are both formed from lead-antimony alloy.
About 9 volts and 300 amperes of direct current are applied to the anodes
surrounding each pot. Trivalent chromium Ions present in the bath migrate
to the anodes where they react with oxygen to form chromic acid. The
ceramic material acts as a selective membrane that prevents the hexavalent
chromium anlons in the bath from flowing to the cathode where they would
be reduced and deposited.
2.2 AIR POLLUTION CONTROL
All three tanks are equipped with double-sided draft hoods that are
Installed along the length of each tank. Each hood contains one
continuous slot that is equal to the tank length and 5.08 centimeters (cm)
(2.0 inches [1n.]) wide. Each slot is reinforced with inserts spaced
approximately 30.5 cm (12.0 1n.) apart.
All three tanks are ducted together and vented to a fume scrubber
located outside of the plant building. The scrubber is a horizontal-flow
single packed-bed unit that 1s equipped with a self-contained
redrculatlon system. The fume scrubber was manufactured by Duall
Industries, Inc. (Model No. F-101). Figure 2-2 presents a diagram of the
scrubber provided by Dual!. The scrubber was purchased as used equipment
and was Installed at the plant 1n 1984. Duall personnel inspected the
scrubber in July 1986 and made the following recommendations to ensure
normal scrubber operating conditions: (1) the angle of the ductwork entry
at the inlet transition of the scrubber should be njpositioned to direct
the gas flow toward the center of the packed bed and to prevent scrubber
water from entering the ductwork, (2) the spray nozzles should be cleaned
and the nozzle velocity should be upgraded to design specifications, and
(3) minor cracks in the scrubber housing should be sealed. The plant
corrected these problems before emission testing was performed.
The gas flow rate to the scrubber 1s 297 acutal cubic meters per
minute (10,500 actual cubic feet per minute), and_the water flow rate 1s
2-2
-------
about 130.5 liters per minute (34.5 gallons per minute). The pressure
drop across the scrubber is 0.5 kilopascals (2 Inches of water column).
Removal of chromic acid mist from the inlet gas stream is
accomplished by reducing the velocity of the entering gas stream to less
than 152 meters per minute (500 feet per minute) and spraying it with
water. The water is sprayed countercurrent to the flow of the gas stream
through six nozzles. The saturated gas stream then passes through a
packed bed of polypropylene, spherical-type mass packing that is
continuously washed with water. The packed bed is 142.2 cm (56 in.) in
height and width and 30.5 cm (12 in.) in depth. The entrained mist and
water droplets impinge on the packing and are carried away in the
washwater. Behind the packed bed is a two-stage mist elimination section
that eliminates any entrained water droplets. The first stage allows
larger droplets to settle by gravity to the bottom of the scrubber. The
second stage contains a series of vertically-mounted chevron blades made
of polyvinyl chloride that change the direction of the gas flow four times
at 30° angles, which forces chromium droplets to impinge on the blades.
The mist eliminator is not washed down but is inspected frequently. If
wetting appears in the mist eliminator section, the packed bed is
reconditioned to prevent the breakthrough of droplets.
The scrubber water drains Into a sump in the bottom of the scrubber
and 1s redrculated by a 0.75-horsepower pump. A sensor is used to
monitor the water level in the sump which contains about 378 liters («,)
(100 gallons [gal]) of water. About four times per day, 95 a (25 gal) of
clean water are automatically added over the packed bed when the sensor
indicates that water is needed to make up for evaporation losses. The
scrubber water 1s drained to the plating tanks approximately once per day
to make up for plating solution evaporation losses. The scrubber is then
recharged with clean water. Grab samples of the scrubber water that were
taken one month before emission testing was conducted showed that the
chromic acid concentration of the scrubber water under normal conditions
1s about 1.5 g/n (0.2 oz/gal).
2-3
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2.3 PROCESS CONDITIONS DURING TESTING
Many hard chromium plating facilities that use scrubbers recirculate
the scrubber water continuously from several hours to several weeks to
reduce water consumption and wastewater treatment costs and to recover
chromic acid for use as plating solution makeup. Therefore, the purpose
of this emissions test was to assess the effect of increasing chromic acid
concentrations in the scrubber water on scrubber performance.
The target level scrubber water chromic acid concentrations selected
for testing were 0.0, 30, 60, and 120 g/a (0.0, 4, 8, and 16 oz/gal). The
target levels of 0.0, 30, and 60 g/a (0.0, 4, and 8 oz/gal) were selected
to represent the range of concentrations that would occur under normal
operating conditions. The target level of 120 g/a (16 oz/gal) was
selected to represent worst case conditions.
Three mass emission test runs were conducted at the inlet and outlet
of the scrubber for each of the four target level concentrations. Each
test run was conducted for 2 hours. The plant manager spiked the scrubber
water with plating solution taken from the 23-foot plating tank at
concentrations near the target levels. Grab samples of the scrubber water
were taken from the scrubber recirculation sump at the beginning, middle,
and end of each test run and analyzed by spectrophotometer at the test
site to monitor chromic acid concentrations. The target and actual
scrubber water concentrations observed during testing are presented in
Table 2-2. The scrubber operated normally throughout the test runs.
The process was operating normally during the tests. Process
operating parameters such as the voltage, current, and plating solution
temperature were monitored and recorded during each mass emission test
run. Also recorded were the current and plating time for each individual
job or item being plating during each test run. Data sheets documenting
the process parameters that were recorded during each mass emission test
run (Nos. 1-1 through 1-12 and 0-1 through 0-12) are presented in
Appendix E. Data on the average operating parameters recorded are
presented in Table 2-3. Because the third tank was not in operation
during the test, the ventilation hood for the tank was dampered off to
increase the ventilation rate for the 23-foot and 10-foot tanks.
2-4
-------
The total amount of current supplied to the work stations during each
test run is calculated in terms of ampere-hours and included in
Appendix E. A summary of the total current values is presented in
Table 2-4. As shown in Table 2-4, the total amount of current supplied to
the tanks during emission test runs 1 through 3 ranged from 12,000 to
13,000 ampere-hours. For test runs 4 through 6, the total current values
were 30 to 40 percent lower (8,000 to 9,000 ampere-hours) and for test
runs 7 through 12 the total current values were 50 to 60 percent lower
(5,500 to 6,500 ampere-hours) than the total current values for test
runs 1 through 3. The plant manager stated that a typical work load for
the two tanks is about 6,000 ampere-hours.
The amount and type of work plated during the emission test runs
varied depending on the plant's scheduled work load. For the 23-foot
tank, work stations 7 and 10 were operated simultaneously during test
runs 1 through 6. For test run 1 at work station 7, one porous pot was
used during the first hour of the test run, and one cast iron part was
plated during the second hour of the test run. For test runs 2 through 6
at work station 7, one porous pot was used for all five test runs. For
test runs 1 through 6 at work station 10, dummy parts were plated because
the plant did not have work to plate at this work station. Lease bars for
warp knitting machines were used as dummy parts for test runs 1 through 3,
and both lease bars and angle iron were used as dummy parts for test
runs 4 through 6. Only work station 10 was operated during test runs 7
through 12. One steel tube (about 6.0 m [19.75 ft] in length) was plated
during each of these six test runs. Plating was stopped for about
5 minutes in the middle of each test run to rotate the tube.
For the 10-foot tank, five work stations were operated for part or
all of the test runs except for test runs 6 and 9. Work station 1 was not
operated during test run 6, and work stations 3 and 4 were not operated
during test run 9. The work plated during emission testing included steel
shafts and gears for engine components and steel pins and latches for
packaging machines. Two to four shafts or gears were plated at each work
station from 30 minutes to 4 hours. Pins and latches were mounted on
plating racks and plated from 15 to 40 minutes. One porous pot was used
at work station 1 during test runs 1, 7, 8, and 9.
2-5
-------
Grab samples were taken from both plating tanks during each mass
emission test run to monitor the chromic acid concentration of the plating
solution. The chromic acid concentration of the grab samples is reported
in Section 3.3 (Table 3-5). The plating solution in the 23-foot tank was
air agitated for test runs 3 through 12 to maintain a uniform chromic acid
concentration throughout the plating solution. The plant manager
considered air agitation of the plating solution to be normal operating
procedure. The tank freeboard space was maintained at about 15 cm
(6 1n.), which prevented plating solution from splashing into the
ventilation hoods.
Sampling at the inlet and outlet was interrupted only once to change
test ports except for test run 11, which was interrupted four times. Test
run 11 was first interrupted after 3 minutes of testing for 38 minutes to
Increase the chromic acid concentration of the scrubber water, a second
and third time for a total of 12 minutes at the inlet and 8 minutes at the
outlet during the first hour of testing, and a fourth time to change test
ports between the first and second hour of testing. Test run 11 was not
interrupted during the second hour of testing. Port changes at the inlet
took from 3 to 8 minutes except for those during test runs 2 and 3, which
took 17 and 39 minutes, respectively. Port changes at the outlet took
from 2 to 8 minutes.
2-6
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WALL
DUALL
SINGLE
PACKED-BED
SCRUBBER
LEGEND:
AIRFLOW
MALL
ro
i
DEEP
TANK
HOODS -4
r
HOODS
23-FOOT TANK
/
HOODS
10-FOOT
TANK
Figure 2-1. Schematic of Piedmont Industrial Plating hard chromium plating operation.
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DUALL INDUSTRIES. INC OWOSSQ Ml
DUALL JOB NO
PURCHASER
PURCHASER PO NO
PURCHASER LOCATION
JOB LOCATION
SPECIFICATION NO
PRESSURE DROP
LIQijIO perip.rULAT!Q« RATE
LIQUID PRESSURE
MAKEUP RATE
RECIRCULATION PUMP
PUMP CAPACITY
PUMP VOLTAGE
D-IOI-IOI6
flQIFUMC SCRUBBER
Figure 2-2. Diagram of Dual! F-101 horizontal-flow single packed-bed fume scrubber
-------
TABLE 2-1. DIMENSIONS AND OPERATING PARAMETERS OF HARD CHROMIUM
PLATING TANKS AT PIEDMONT INDUSTRIAL PLATING
Tank
23-foot
10-foot
Dimensions
(1. w, d_),
n (ft)*
7.0, 0.9. 1.2
(23.0, 3.0, 4.0)
3.0, 0.9, 1.2
(10.0, 3.0. 4.0)
Capacity,
* (gai)
7.813
(2,064)
3,400
(898)
Voltage,
VOltSD
12
12
Current-
amperes0 c
9,000
5,000
Method of
cooling
Water
Water
jjL = length, w = width, d = depth.
Maximum operating values.
CA total of four work stations can be used 1n the 23-foot tank. One of the work stations is charged
with a 6,000-ampere rectifier and three of the work stations each are charged with a 1,000-ampere
7s rectifier. A total of five work stations are used in the 10-foot tank. Each work station is charged
10 with separate 1,000-ampere rectifiers.
-------
TABLE 2-2. AVERAGE SCRUBBER WATER CHROMIC ACID
CONCENTRATIONS FOR EACH TEST RUN
Target Actual
Run No. concentration, concentration,
Inlet/outlet
1-1/0-1
1-2/0-2
1-3/0-3
1-4/0-4
1-5/0-5
1-6/0-6
1-7/0-7
1-8/0-8
1-9/0-9
1-10/0-10
1-11/0-11
1-12/0-12
g/a (oz/gal)
0.0
0.0
0.0
30.0 (4.0)
30.0 (4.0)
30.0 (4.0)
60.0 (8.0)
60.0 (8.0)
60.0 (8.0)
120.0 (16.0)
120.0 (16.0)
120.0 (16.0)
g/i (oz/gal)
1.38 (0.185)
1.73 (0.231)
1.75 (0.234)
25.24 (3.37)
25.54 (3.41)
24.64 (3.29)
50.56 (6.75)
45.24 (6.04)
41.94 (5.60)
78.94 (10.54)3
115.19 (15.38)
105.68 (14.11)
aShortly before the end of this test run plating personnel
inadvertantly drained the scrubber water into the 23-foot
plating tank to makeup for plating solution evaporation
losses.
2-10
-------
TABLE 2-3. AVERAGE OPERATING PARAMETERS RECORDED DURING EACH MASS EMISSION SOURCE TEST RUN
ro
i
Test run No.
Inlet/Outlet
1-1/0-1
1-2/0-2
1-3/0-3
1-4/0-4
1-5/0-5
1-6/0-6
1-7/0-7
Tank
23-ft
10-ft
23-ft
10-ft
23-ft
10-ft
23-ft
10-ft
23-ft
10-ft
23-ft
10-ft
23-ft
10-ft
Operating
voltage, volts
9.2
6.6
9.3
6.7
9.3
7.1
9.7
5.6
9.7
5.8
9.7
6.0
9.0
6.0
Operating
current, amperes
1,562
700
1,622
702
1,634
720
1,756
171
1,800
245
1,826
275
2,000
426
Temperature
of plating
solution, °C (°F)
57 (134)
60 (140)
57 (134)
60 (140)
58 (136)
60 (140)
58 (137)
60 (140)
59 (138)
60 (140)
59 (138)
60 (140)
57 (135)
60 (140)
Pressure drop
of scrubber,
kPa (1n. w.c.)
0.55 (2.2)
0.55 (2.2)
0.55 (2.2)
0.55 (2.2)
0.55 (2.2)
0.55 (2.2)
0.52 (2.1)
0.52 (2.1)
0.52 (2.1)
0.52 (2.1)
0.52 (2.1)
0.52 (2.1)
0.52 (2.1)
0.52 (2.1)
(continued)
-------
TABLE 2-3. (continued)
r\>
i—•
ro
Inlet/Outlet
1-8/0-8
1-9/0-9
1-10/0-10
1-11/0-11
1-12/0-12
Tank
23-ft
10-ft
23-ft
10-ft
23-ft
10-ft
23-ft
10-ft
23-ft
10-ft
Operating
voltage, volts
8.2
7.1
8.0
6.9
8.0
6.9
8.5
6.5
8.5
6.6
Operating
current, amperes
1,946
489
2,000
378
2,000
366
2,000
405
2,000
415
Temperature
of plating
solution, °C (°F)
59 (138)
60 (140)
59 (138)
60 (140)
58 (136)
60 (140)
58 (136)
60 (140)
58 (136)
60 (140)
Pressure drop
of scrubber,
kPa (1n. w.c.)
0.50 (2.0)
0.50 (2.0)
0.50 (2.0)
0.50 (2.0)
0.50 (2.0)
0.50 (2.0)
0.52 (2.1)
0.52 (2.1)
0.50 (2.0)
0.50 (2.0)
-------
TABLE 2-4. TOTAL CURRENT SUPPLIED TO THE TANKS
DURING EACH MASS EMISSION TEST RUN
Test run No.
Inlet/Outlet
I -1/0-1
1-2/0-2
1-3/0-3
1-4/0-4
1-5/0-5
1-6/0-6
1-7/0-7
1-8/0-8
1-9/0-9
Ampere-hours
Tank
23-ft
10-ft
Total
23-ft
10-ft
Total
23-ft
10-ft
Total
23-ft
10-ft
Total
23-ft
10-ft
Total
23-ft
10-ft
Total
23-ft
10-ft
Total
23-ft
10-ft
Total
23-ft
10-ft
Total
Inlet
6,213
6.005
12,218
6,492
6,731
13,223
6,524
6.484
13,008
7,039
1,470
8,509
7,154
2,253
9,407
7,312
1,129
8,441
3,998
2,473
6,471
3,326
3.106
6,432
3,996
1.465
5,461
Outlet
6,213
6.005
12,218
6,492
6.731
13,223
6,546
6.501
13,047
7,115
1,489
8,604
7,262
2.308
9,570
7,372
1.119
8,491
3,996
2.491
6,487
3,325
3.041
6,366
4,029
1.445
5,474
(continued)
2-13
-------
TABLE 2-4. (continued)
Test run No.
Inlet/Outlet
Tank
Ampere-hours
Inlet
Outlet
1-10/0-10
1-11/0-11
1-12/0-12
23-ft
10-ft
Total
23-ft
10-ft
Total
23-ft
10-ft
Total
3,897
2.439
6,336
3,997
2,227
6,224
3,831
2.827
6,658
3,864
2,444
6,308
4,030
2.245
6,275
3,830
2.847
6,677
2-14
-------
3.0 SUMMARY OF RESULTS
Chromium (hexavalent and total) testing using Method 5 procedures and
Method 13-type impinger trains was conducted at the inlet and outlet of the
packed-bed scrubber controlling the 23-foot and 10-foot plating tanks. This
was done at four different scrubber water chromic acid concentrations ranging
from 0.22 to 13-3 oz of chromic acid per gallon of water. Table 3-1 summarizes
the testing schedule for these tests. In addition, a series of tests were also
conducted at the scrubber inlet and outlet to evaluate three alternative
screening methods for estimating emissions of chromium from chromium plating
operations (see Section 3-5)-
In brief, from the results of the impinger train testing, the uncontrolled
emissions from the tanks with the scrubber liquor at 0.22 oz/gal averaged 0.23
pounds per hour of hexavalent chromium and 0.26 pounds per hour of total
chromium. The controlled emissions with the scrubber water at 0.22 oz/gal
averaged 0.00096 pounds per hour of hexavalent chromium and 0.0014 pounds per
hour of total chromium. The resulting collection efficiency on a mass emission
rate basis was 99-5^% for hexavalent chromium and 99-38% for total chromium.
The collection efficiency ranged from 99.22% to 99-5**% for hexavalent chromium
and from 99-16% to 99-38% for total chromium. One of the three potential
screening methods evaluated for estimating emissions of chromium from chromium
plating operations appears to be promising. This method involves collecting
the chromium emissions on a 37-mm Teflon filter using a disposable plastic
filter cassette and a portable personnel sampling pump. Further evaluation is
recommended in conjunction with impinger train testing to obtain a better
estimate of the screening method precision and accuracy.
Discussions detailing all the results obtained are presented in the
following sections. Computer printouts of the emission calculations are
presented in Appendix A. Original field data sheets and the analytical data are
located in Appendix B.
3-1
-------
TABLE 3.1. TESTING SCHEDULE FOR PIEDMONT INDUSTRIAL PLATING
Date
(1986)
8/19
8/20
8/21
8/22
Sample Type
Cr*g, Total Cr
Cr+5, Total Cr
Cr , Total Cr
Cr*6-, Total Cr
Cr*fi, Total Cr
Cr , Total Cr
Cr*g, Total Cr
Cr*g, Total Cr
Cr , Total Cr
Cr*g, Total Cr
Cr £, Total Cr
Cr , Total Cr
Scrubber Inlet
Run
No.
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
1-10
1-11
1-12
Test Time
24 h clock
0847-1100
1131-1342
1423-1640
1046-1325
1347-1600
1624-1832
1051-1258
1350-1556
1639-1846
0831-1036
1113-1403
1428-1632
Scrubber Outlet
Run
No.
0-1
0-2
0-3
0-4
0-5
0-6
0-7
0-8
0-9
0-10
0-11
0-12
Test Time
24 h clock
0847-1055
1132-1339
1423-1627
1046-1255
1348-1553
1626-1830
1050-1253
1352-1555
1639-1843
0830-1033
1114-1400
1428-1631
3-2
-------
3.1 HEXAVALENT CHROMIUM AND TOTAL CHROMIUM
The chromium emissions tests, along with the determination of the
associated flue gas flow rates were conducted at both the scrubber inlet and
outlet at four scrubber liquor chromic acid concentrations. The samples were
collected using a Method 13-type impinger train with no backup filter. For
analysis, a measured portion of each impinger sample was initially filtered for
insoluble chromium. It was assumed that all insoluble chromium was in the
trivalent state and all soluble chromium was in the hexavalent state. The
trivalent chromium was measured using inductively coupled argon plasmography
(ICAP). The soluble (hexavalent) chromium in each sample was measured using
the diphenylcarbazide colorimetric method as described in the tentative EPA
method for hexavalent chromium. Total chromium concentrations for each sample
were calculated as the sum of the hexavalent chromium concentration and the
trivalent chromium concentration. A complete description of each sampling
location and the sampling and analytical procedures are given in Chapter 4 and
Appendix C.
3.1.1 Scrubber Inlet
The scrubber inlet results represent the uncontrolled emissions from the
32-foot and 10-foot tanks at Piedmont Industrial Plating Company. Prior to
testing, a pitot tube traverse was conducted to determine the amount of flow
misalignment. The results demonstrated that the flow was parallel with the
duct (with an average flow misalignment angle of 5-5°) in spite of the
relatively short, straight runs of duct before and after the sampling
location. Since the gas conditions and chromium concentrations at the scrubber
inlet should not have been affected by the changing scrubber liquor concen-
trations (which is confirmed by the data), the discussion of the results will
simultaneously address the values for all twelve inlet runs.
Flue Gas Conditions and Isokinetic Sampling Rate -• A summary of the flue
gas conditions at the scrubber inlet is presented in Table 3«2. The volumetric
flow rates were consistent at the inlet and averaged 17,^00 actual cubic meters
per hour (614,000 actual cubic feet per hour). The flow rate at the inlet was
approximately 5% less than the outlet flow rate which is within reasonable
measurement error. The flue gas temperature averaged 26°C (78°F), with a
moisture content of 2.7 percent. The oxygen, carbon dioxide, and carbon
3-3
-------
TABLE 3.2. SUMMARY OF FLUE GAS CONDITIONS
Run
No.
Date
(1986)
Volumetric Flow Rate
Actual
a
Standard
acrnh
xlO3
acfh
x 103
dscmh
xlO3
dscfh
xlO3
Stack
Temperature
Moisture
CO,
Isokinetic
%
Scrubber Inlet. 0.22 oz/gal CrO,
1-1
1-2
1-3
8/19
8/19
8/19
Average i
17.6
17.8
18.0
17.8
622
629
637
629
16.5
16.5
16.7
16.6
583
584
589
585
25
26
26
26
77
79
79
78
2.5
3.0
3.4
3.0
20.9
20.9
20.9
20.9
0.0
0.0
0.0
0.0
98.7
99.0
99.5
Scrubber Inlet, 3.36 oz/gal CrO,
1-4
1-5
1-6
8/20
8/20
8/20
Average
17.1
17.0
17.1
17.1
603
600
604
602
16.0
15.9
16.1
16.0
566
563
567
565
26
25
25
25
78
77
77
77
2.9
2.9
3.0
2.9
20.9
20.9
20.9
20.9
0.0
0.0
0.0
0.0
100.2
97.7
97.7
Scrubber Inlet. 6.13 oz/gal CrO.-
1-7
1-8
1-9
8/21
8/21
8/21
Average
17.2
17.6
17.5
17.4
608
621
618
616
16.2
16.5
16.4
16.4
574
582
578
578
26
28
28
27
78
82
83
81
2.6
2.5
2.5
2.5
20.9
20.9
20.9
20.9
0.0
0.0
0.0
0.0
98.0
98.3
98.1
Scrubber Inlet. 13.3 oz/gal CrO.
1-10
1-11
1-12
8/22
8/22
8/22
Average
17.3
17.2
17.1
17.2
612
608
604
608
16.5
16.3
16.1
16.3
583
574
569
575
24
26
26
25
75
78
79
77
2.1
2.5
2.5
2.4
20.9
20.9
20.9
20.9
0.0
0.0
0.0
0.0
97.2
97.1
97.0
Scrubber Outlet, 0.22 oz/gal CrO,
0-1
0-2
0-3*
8/19
8/19
8/19
Average
18.7
18.9
18.7
18.8
660
668
662
664
17.6
17.9
17.5
17.8
621
631
617
626
25
26
27
26
77
78
80
78
2.5
2.0
2.8
2.2
20.9
20.9
20.9
20.9
0.0
0.0
0.0
0.0
100.6
103.6
102.7
Scrubber Outlet, 3.36 oz/gal CrO,
0-4
0-5
0-6
8/20
8/20
8/20
Average
18.1
18.5
18.0
18.2
638
652
634
641
17.1
17.5
17.0
17.2
605
619
601
608
26
26
26
26
78
78
79
78
2.0
2.2
2.1
2.1
20.9
20.9
20.9
20.9
0.0
0.0
0.0
0.0
102.1
103.0
103.3
Scrubber Outlet. 6.13 oz/gal CrO,
0-7
0-8
0-9
8/21
8/21
8/21
Average
18.4
18.3
18.1
18.3
650
648
639
646
17.4
17.4
17.1
17.3
616
613
605
611
26
27
27
27
78
81
80
80
12.7
:2.3
'.1.4
2.5
20.9
20.9
20.9
20.9
0.0
0.0
0.0
0.0
100.0
100.8
101.5
Scrubber Outlet, 13.3 oz/gal CrO,
0-10
0-11
0-12
8/22
8/22
8/22
Average
18.0
18.1
17.9
18.0
637
639
632
636
17.2
17.1
17.1
17.1
607
603
605
605
26
27
26
26
78
80
79
79
'.1.2
:>.7
1.5
2.1
20.9
20.9
20.9
20.9
0.0
0.0
0.0
0.0
101.1
101.4
101.3
Volumetric flow rate in actual cubic meters per hour (acmh) and actual cubic feet per hour (acfh)
.at stack conditions.
Volumetric flow rate in dry standard cubic meters per hour (dscmh) and dry standard cubic feet
tper hour (dscfh).
Results for this run not included in average because heavy rain during run entered stack and
may have biased results.
3-4
-------
monoxide content was that of ambient air at 20.9t 0.0, and 0.0 percent, respec-
tively. The volumetric flow rate at standard conditions averaged 16,300 dry
standard cubic meters per hour (576,000 dry standard cubic feet per hour).
Standard conditions are 20°C (68°), 760 mm Hg (29.92 in. Hg), and dry basis.
The isokinetic sampling rates were well within the allowable for all twelve
sample runs.
Hexavalent Chromium Emissions - The hexavalent chromium emissions for each
test run (see Table 3-3) were fairly consistent for eleven out of the twelve
runs; however, the results indicate some variation in emissions based on
process operation. The results for run 1-4 were about; 3 times higher than for
the other runs, and it is suspected that the nozzle may have contacted the duct
wall at some time during the run. Therefore, the results for this run have not
been included in any of the averages. The uncontrolled hexavalent chromium
emissions averaged 5-5 milligrams per dry standard cubic meter (0.0024 grains
per dry standard cubic foot) and 0.091 kilograms per hour (0.199 pounds per
hour).
Total Chromium Emissions - The total chromium emissions for each test run
also were fairly consistent for eleven of the twelve test runs and averaged
about 11% higher than the hexavalent chromium emissions. The uncontrolled
emissions averaged 6.16 milligrams per dry standard cubic meter (0.0027 grains
per dry standard cubic foot) and 0.100 kilograms per hour (0.221 pounds per
hour).
3.1.2 Scrubber Outlet
The scrubber outlet represents the controlled emissions from the 23-foot
and 10-foot plating tanks. Since the flue gas conditions did not vary with the
changing scrubber water concentrations, the results for all twelve outlet runs
are discussed in the following subsection. The chromium emission results at
each scrubber water chromic acid concentration are addressed in separate
subsections.
3-5
-------
TABLE 3.3. SUMMARY OF HEXAVALENT CHROMIUM AND TOTAL CHROMIUM EMISSIONS
Run
No.
Date
(1986)
Hexavalent Chromium
concentration
mg/dscm
gr/dscf
xlO-3
mass emissions
kg/h
xlO-3
Ib/h
xlO-3
Total Chromium
concentration
mg/dscm
gr/dscf
xlO'3
mass emissions
kg/h
xlO-3
Ib/h
xlO-3
Scrubber Inlet, 0.22 oz/ga.L CrO,
1-1
1-2
1-3
8/19
8/19
8/19
Average
4.499
7.065
7.035
6.20
1.966
3.087
3.074
2.71
74.2
116.9
117.4
103
163.7
257.6
258.7
227
5.156
7 . 978
8.057
7.07
2.253
3.486
3.521
3.09
85.1
132.0
134.4
117
187.6
290.9
296.3
258
Scrubber Inlet. 3.36 oz/gal CrO-
1-4*
1-5
1-6
8/20
8/20
8/20
Average
15.941
5.481
6.421
5.95
6.966
2.395
2.806
2.60
255.4
87.4
103.1
95.2
563.1
192.7
227.2
210
18.021
5.992
7.010
6.150
7.875
2.619
3.063
2.84
288.7
95.6
112.5
104
636.6
210.7
248.1
229
Scrubber Inlet. 6.13 oz/gal CrO,
1-7
1-8
1-9
8/21
8/21
8/21
Average
4.905
4.586
4.379
4.62
2.143
2.004
1.914
2.02
79.7
75.6
71.7
76.3
175.7
166.6
158.1
167
5.616
5.000
4.1)02
5.14
2.454
2.185
2.098
2.25
91.2
82.4
78.6
84.1
201.2
181.7
173.3
185
Scrubber Inlet. 13.3 oz/ga.'L CrO,
1-10
1-11
1-12
Avera
8/22
8/22
8/22
ge
6.065
5.495
4.618
5.39
2.650
2.401
2.018
2.36
100.1
89.4
74.4
88.0
220.8
197.0
164.1
194
6.!>71
6.086
5 . 118
5.93
2.872
2.660
2.236
2.59
108.5
99.0
82.5
96.7
239.2
218.2
181.9
213
Scrubber Outlet, 0.22 oz/gaJL Cr03
0-1
0-2
0-3**
8/19
8/19
8/19
Average
0.0217
0.0275
0.1463
0.0246
0.0095
0.0120
0.0639
0.0108
0.381
0.491
2.557
0.436
0.840
1.083
5.637
0.962
0 . 037
0 . 036
0.158
0.036
0.016
0.016
0.069
0.016
0.644
0.648
2.767
0.646
1.420
1.428
6.101
1.42
Scrubber Outlet, 3.36 oz/gal CrO,
0-4
0-5
0-6
8/20
8/20
8/20
Average
0.0233
0.0276
0.0253
0.0254
0.0102
0.0121
0.0111
0.0111
0.400
0.484
0.431
0.438
0.883
1.067
0.950
0.967
0.040
0.047
0.045
0.044
0.017
0.021
0.020
0.019
0.678
0.829
0.774
0.760
1.494
1.828
1.707
1.68
Scrubber Outlet, 6.13 oz/gal CrO,
0-7
0-8
0-9
8/21
8/21
8/21
Average
0.0301
0.0392
0.0338
0.0344
0.0132
0.0171
0.0147
0.0150
0.517
0.680
0.578
0.592
1.139
1.500
1.274
1.30
0.035
0.044
0.039
0.039
0.015
0.019
0.017
0.017
0.594
0.769
0.672
0.678
1.309
1.696
1.481
1.50
Scrubber Outlet, 13.3 oz/gal CrO
0-10
0-11
0-12
8/22
8/22
8/22
Average
0.0319
0.0321
0.0395
0.0345
0.0140
0.0140
0.0172
0.0151
0.549
0.548
0.676
0.591
1.120
1.208
1.490
1.27
0.042
0.044
0.053
0 . 046
0.018
0.019
0.023
0.020
0.713
0.755
0.905
0.791
1.573
1.664
1.996
1.74
* Results for this run not included in
wall during testing.
••Results for this run not included in
biased results.
average; it is suspected that nozzle may have contacted duct
average; heavy rain during run entered stack and may have
3-6
-------
Figure 3~1 presents the ranges for the hexavalent chromium emission
measurements made at four levels of scrubber water chromic acid concentrations.
[EPA to add explanatory paragraph.]
The average total chromium emissions measured at the outlet were 15% to
higher than the average hexavalent chromium emissions measured at the
corresponding scrubber water chromic acid concentration. This was in contrast
to the total chromium emissions measured at the inlet which averaged about 11%
higher than the hexavalent chromium emissions, at all four scrubber water
concentrations. [EPA to add explanatory paragraph.]
3-7
-------
| I
_, 0.22 oz/gal
_, 3.36 oz/gal
j 6.13 oz/gal
13.3 oz/gal
0.008
'
0.010
0.012 0.014
, 0.22 oz/gal
I 3.36 oz/gal
0.016
0.018
grains/dscf
.. 6.13 oz/gal
13.3 oz/gal
0.06 0.10 0.14
, _ l _ j
0.22 oz/gal
0.1B
0.22
i . mg/amp-hr
3.36 oz/gal
, 6.1.3 oz/gal
13.3. oz/gal
Figure 3~1-
Ranges for measurements of hexavalent chromium emissions
conducted at four scrubber water chromic acid concentrations
for mass emission rate, concentration, and emission rates in
units of process rate.
3-8
-------
Flue Gas Conditions and Isokinetic Sampling Rate - A summary of the flue
gas conditions at the scrubber outlet is presented in Table 3-2. The results
from run 0-3 are not included in any of the averages because heavy rain during
that run entered the stack and may have biased the results. For subsequent
runs, a rain cap was constructed and installed on the stack.
The volumetric flow rate averaged 18,300 actual cubic meters per hour
(647,000 actual cubic feet per hour) with a flue gas temperature average of
26°C (78°F) and a moisture content of 2.2 percent. The oxygen, carbon dioxide,
and carbon monoxide content was that of ambient air at 20.9, 0.0, and 0.0
percent, respectively. The volumetric flow rate at standard conditions
averaged 17,400 dry standard cubic meters per hour (613,000 dry standard cubic
feet per hour). Standard conditions are 20°C (68°), 760 mm Hg (29.92 in. Hg),
and dry basis. The isokinetic sampling rates were well within the allowable
for all twelve sample runs.
Hexavalent and Total Chromium Emissions (Scrubber Liquor at 0.22 oz/gal) -
The controlled hexavalent chromium emissions for test runs 0-1 and 0-2 were
fairly consistent when compared to the simultaneous inlet runs. The results
for run 0-3 were approximately 6 times greater than the other two runs. It is
believed that the heavy rains entering the stack during this run may have
solubilized chromium on the stack walls, which became re-entrained and biased
the results high. Therefore, the results of this run are not included in the
averages. Hexavalent chromium emissions for runs 0-1 and 0-2 averaged 0.025
milligrams per dry standard cubic meter (0.00001 grains per dry standard cubic
foot) and 0.00044 kilograms per hour (0.00096 pounds per hour).
Controlled total chromium emissions for test runs 0-1 and 0-2 averaged
about 48# higher than the hexavalent chromium emissions. The total chromium
emissions averaged 0.036 milligrams per dry standard cubic meter (0.000016
grains per dry standard cubic foot) and 0.00065 kilograms per hour (0.0014
pounds per hour).
Hexavalent and Total Chromium Emissions (Scrubber Liquor at 3-36 oz/gal) -
The hexavalent chromium emissions were fairly consistent for each of the three
test runs (see Table 3-3)- They were not significantly different from the
hexavalent chromium results with the scrubber liquor chromic acid concentration
at 0.22 oz/gal. The controlled hexavalent chromium emissions averaged 0.025
3-9
-------
milligrams per dry standard cubic meter (0.00001 grains per dry standard cubic
foot) and 0.00044 kilograms per hour (0.00097 pounds per hour).
The total chromium emissions were consistent for each test run and aver-
aged about 74# higher than the hexavalent chromium emissions. The controlled
emissions averaged 0.044 milligrams per dry standard cubic meter (0.00019
grains per dry standard cubic foot) and 0.00076 kilograms per hour (0.0017
pounds per hour).
Hexavalent and Total Chromium Emissions (Scrubber Liquor at 6.13 oz/gal) -
The controlled hexavalent chromium emissions for the test runs were fairly
consistent from run to run. They averaged about 40# higher than the values
measured when the scrubber liquor chromic acid concentration was at 0.22
oz/gal, and averaged 0.034 milligrams per dry standard cubic meter (0.000015
grains per dry standard cubic foot) and 0.00059 kilograms per hour (0.0013
pounds per hour).
The controlled total chromium emissions for each test run were very
consistent and averaged about 15# higher than the hexavalent chromium
emissions. The total chromium emissions averaged 0.039 milligrams per dry
standard cubic meter (0.000017 grains per dry standard cubic foot) and
0.00068 kilograms per hour (0.0015 pounds per hour).
Hexavalent and Total Chromium Emissions (Scrubber Liquor at 13-3 oz/gal) -
The controlled hexavalent chromium emissions for the test runs were fairly
consistent from run to run. Overall, they averaged about 40# higher than those
measured when the scrubber liquor chromic acid concentration was at 0.22
oz/gal. For the three runs, the hexavalent chromium emission averages were
0.035 milligrams per dry standard cubic meter (0.000015 grains per dry standard
cubic foot) and 0.00059 kilograms per hour (0.0013 pounds per hour).
The controlled total chromium emissions for each test run were very
consistent and averaged about 37# higher than the hexavalent chromium
emissions. The controlled total chromium emissions averaged 0.046 milligrams
per dry standard cubic meter (0.000020 grains per dry standard foot) and
0.00079 kilograms per hour (0.0017 pounds per hour).
3-10
-------
3.2 EMISSIONS IN UNITS OF PROCESS RATE AND CONTROL EQUIPMENT COLLECTION
EFFICIENCY
The emission rates in units of process rate are presented in terms of
grams of emissions per hour per square foot of tank surface area and in units
of milligrams emissions per amperage input to the plating operation expressed
in ampere-hours. To determine the collection efficiency of the scrubber, the
mass emission rates in milligrams per hour (uncontrolled emissions and
controlled emissions) were used for the calculations.
3.2.1 Emissions in Units of Process Rate
The emissions in terms of units of process rate are expressed in relation
to two process parameters, as shown in Table 3-4• The first is milligrams of
emissions per hour per amperage input per hour into the plating operation. The
second is grams of emissions per hour per square foot of tank surface area.
The surface area of the two tanks combined was 99 ft for all tests.
3.2.2 Scrubber Collection Efficiency
The collection efficiency of the packed-bed scrubber is presented in Table
3.4. It was measured with the scrubber recirculating water or scrubber water
at four different chromic acid concentrations to evaluate the effect of
increasing the concentration on scrubber efficiency. As is shown in Table 3.4,
the collection efficiency did not decrease significantly with scrubber liquor
chromic acid concentrations around 10 times the normal concentration at this
plant. At a scrubber water concentration of 0.22 oz/gal, the scrubber
collection efficiency averaged 99-5^ percent by weight for hexavalent chromium
and 99-38 percent by weight for total chromium. At a scrubber water concen-
tration of 13.3 oz/gal, the scrubber collection efficiency averaged 99-32
percent by weight for hexavalent chromium and 99-16 percent by weight for total
chromium. The collection efficiencies for both hexavalent and total chromium
were fairly consistent.
3.3 ANALYSIS OF CHROME PLATING SOLUTIONS AND SCRUBBER LIQUOR
Grab samples of the chrome plating solution were taken from the plating
tanks at the middle of each run. Grab samples of the scrubber recirculating
water were taken from the scrubber reservoir at the beginning, middle, and end
of each test run. A summary of the results for these samples is shown in
3-11
-------
TABLE 3.4. SUMMARY OF EMISSION RATES IN UNITS OF PROCESS RATE AND EFFICIENCY
Run
Nos.
Process
Rate
amp-hr
Uncontrolled Emissions (Inlet)
hexavalent
chromium
mg
amp-hr
g/h
2
ft *
total
chromium
mg
amp-hr
g/h
2
ft *
Controlled Emissions (Outlet)
hexavalent
chromium
mg
amp-hr
g/h
2
ft *
total
chromium
mg
amp-hr
g/h
2
ft *
Collection Efficiency**
hexavalent
chromium
%
total
chromium
*
Scrubber Liquor. 0.22 oz/gal
I. 0-1
1.0-2
1,0-3***
Avg.
12.218
13.223
13,028
12.720
12.15
17.68
18.02
14.9
0.75
1.18
1.19
0.96
13.93
19.97
20.63
17.0
0.86
1.33
1.36
1.10
0.0624
0.0743
0.393
0.068
0.00384
0.00496
0.0258
0.0044
0.105
0.098
0.425
0.102
0.0065
0.0065
0.0279
0.0065
99.49
99.58
97.82
99.54
99.25
99.51
97.94
99.38
Scrubber Liquor, 3.36 oz/gal
1,0-4***
1,0-5
1,0-6
Avg.
8,556
9.488
8,466
8.980
59.70
18.42
24.36
21.4
2.58
0.883
1.041
0.962
67.48
20.15
26.58
23.4
2.92
0.97
1.14
1.05
0.0935
0.102
0.102
0.102
0.00404
0.00489
0.00435
0.00462
0..158
0.175
0.183
0.179
0.00685
0.00837
0.00782
0.00810
99.84
99.45
99.58
99.52
99.76
99.13
99.31
99.22
Scrubber Liquor, 6.13 oz/gal
1,0-7
1,0-8
1,0-9
Avg.
6.479
6.399
5.468
6,120
24.60
23.63
26.23
24.8
0.805
0.764
0.724
0.764
28.15
25.75
28.75
27.6
0.921
0.832
0.794
0.849
0.159
0.213
0.211
0.194
0.00522
0.00687
0.00584
0.00598
0.183
0.240
0.246
0.223
0.00600
0.00777
0.00679
0.00685
99.35
99.10
99.19
99.22
99.35
99.07
99.14
99.19
Scrubber Liquor, 13.3 oz/gal
1,0-10
1,0-11
1.0-12
Avg.
6,322
6.250
6.668
6.410
31.67
28.61
22.32
27.5
1.011
0.903
0.752
0.889
34.32
31.68
24.75
30.2
1.096
1.00
0.833
0.976
0.174
0.175
0.203
0.184
0.00554
0.00554
0.00683
0.00597
0.226
0.242
0.271
0.246
0.00720
0.00763
0.00914
0.00799
99.49
99.39
99.09
99.32
99.34
99.24
98.91
99.16
* Emission rate in units of grams per hour per square foot of tank surface (gr/hr/ft ) using tank
surface of 99 ft .
** Collection efficiency of control equipment is based on the uncontrolled, and controlled emission
rate in units of emissions per hour.
*** Results for this run not included in average.
+ Average of the inlet and outlet values from Table 2-4.
3-12
-------
Table 3-5- There were no significant differences between any of the tank
solutions with respect to chromic acid concentration. The table shows the
average chromic acid concentration for the scrubber recirculating water for
each day of testing. These average values have been used in the discussions of
the effect of varying the scrubber water concentration on chromium emissions.
Detailed analytical results for all the individual greib samples are presented
in Tables 3.6 and 3-7.
3.4 ANALYSIS FOR CHROMIUM IN IMPINGER SAMPLES
The summary of the analytical results for hexavalent and total chromium
obtained for each impinger train sample is presented in Table 3-8. The summary
of the analytical results for the plating tank and scrubber water grab samples
are, as previously stated, presented in Tables 3-6 and 3-7- The results shown
in these tables for hexavalent chromium (assumed to be all the soluble
chromium) are those obtained by analyzing a measured portion of each sample
using the EPA tentative method for hexavalent chromium "Determination of
Hexavalent Chromium Emissions from Stationary Sources" (see Appendix C). The
results shown for trivalent chromium (assumed to be all the insoluble chromium)
were obtained by taking another measured representative portion of the sample,
filtering it to catch the insoluble chromium, and analyzing the filter for
chromium using inductively-coupled argon plasmography (ICAP). Total catches
for hexavalent, trivalent, and total chromium were calculated using the sample
volume and concentrations(s) of hexavalent and/or trivalent chromium.
Quality assurance audit samples were analyzed using both the chromium
methods; the results are shown in the Quality Assurance Section (5.0). As can
be seen in Table 5-2, no bias was present using either of the methods and,
thus, the results are considered acceptable.
3.5 SUMMARY OF EVALUATIONS AND RESULTS FOR SCREENING METHOD TESTING
The alternative screening methods evaluated included trains using a
personnel sampling pump with either a midget impinger or a 37-mm Teflon filter
and gas detector tubes.
The screening method testing using a personnel sampling pump with a midget
impinger or 37-mm Teflon filter and cassette was conducted for nominal
30-minute sampling runs concurrent with both the inlet and outlet Method
13-type impinger train runs. The personnel sampling pump runs (using either
3-13
-------
TABLE 3.5. SUMMARY OF PLATING SOLUTION AND SCRUBBER RECIRCULATING WATER
CHROMIC ACID CONCENTRATIONS
Run
1,0-1
1,0-2
1,0-3
Date
8/19
8/19
8/19
Average
1,0-4
1,0-5
1,0-6
8/20
8/20
8/20
Average
1,0-7
1,0-8
1,0-9
8/21
8/21
8/21
Average
1,0-10
1,0-11
1,0-12
8/22
8/22
8/22
Average
Chromic Acid Concentration of Solution (oz/gal)
10-Foot Tank
30.30
30.12
29.89
30.10
30.60
30.86
31.76
31.07
30.70
29.89
.26.84
29.14
29.32
30.60
30.60
30.17
23-Foot Tank
30.22
30.54
30.94
30.57
30.34
30.86
30.47
30.56
30.54
30.38
30.22
30.38 '
28.28
28.54
28.80
28.54
Scrubber Water
0.185
0.231
0.234
0.217
3-37
3.41
3-29
3-36
6.75
6.04
5.60
6.13
10.54*
15-38
14.11
13.34
Scrubber water drained into plating tank toward end of this run.
3-14
-------
TABLE 3.6. ANALYTICAL RESULTS FOR CHROMIUM CONCENTRATION
IN 23-FOOT AND 10-FOOT PLATING TANK GRAB SAMPLES
Run
No.
Date
(1986)
Chromium Concentration
Cr+6
g/L
Cr+3
g/L
Total Cr
g/L
10-Foot Plating Tank
1
2
3
4
5
6
7
8
9
10
11
12
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
118.0
117.4
116.4
119.2
120.2
123.7
119.6
116.6
104.6
114.2
119.2
119.2
0.003
0.001
0.011
0.007
0.002
0.006
0.001
0.001
0.002
0.002
0.007
0.001
118.00
117-40
116.41
119.21
120.20
123.71
119.60
116.60
104 . 60
114.20
119.21
119.20
23-Foot Plating Tank
1
2
3
4
5
6
7
8
9
10
11
12
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/21
8/22
8/22
117-7
118.9
120.5
118.2
120.2
118.7
119.0
118.3
117.7
110.2
111.2
112.2
0.003
0.005
0.011
0.007
0.001
0.000
0.002
0.001
0.002
0.001
0.002
0.001
117.70
118.90
120.51
118.21
120.20
118.70
119.00
118.30
117.70
110.20
111.20
112.20
3-15
-------
TABLE 3.7. ANALYTICAL RESULTS FOR CHROMIUM CONCENTRATION
IN SCRUBBER RECIRCULATING WATER GRAB SAMPLES
Run #/
Sample #
1-1
1-2
1-3
2-1
2-2
2-3
3-1
3-2
3-3
4-1
4-2
4-3
5-1
5-2
5-3
6-1
6-2
6-3
7-1
7-2
7-3
8-1
8-2
8-3
9-1
9-2
9-3
10-1
10-2
10-3*
ll-l
11-2
11-3
12-1
12-2
12-3
Date
(1986)
8/19
8/19
8/19
8/19
8/19
8/19
8/19
8/19
8/19
8/20
8/20
8/20
8/20
8/20
8/20
8/20
8/20
8/20
8/21
8/21
8/21
8/21
8/21
8/21
8/21
8/21
8/21
8/22
8/22
8/22
8/22
8/22
8/22
8/22
8/22
8/22
Chromium Concentration
Cr+6
g/L
0.65
0.68
0.82
0.84
0.89
0.98
0.77
1.03
0.94
13.45
12.78
13.09
14.22
12.47
13.15
13.45
12.14
12.77
26.45
27.82
24.54
23.17
24.33
23.04
23.72
21.67
19-96
52.27
62.38
8.34
57.18
60.36
61.95
53.39
58.56
52.78
Cr+3
g/L
0.005
0.002
0.002
0.001
0.002
0.003
0.004
0.001
0.001
0.001
0.001
0.004
0.002
0.001
0.002
0.001
0.001
0.001
0.003
0.003
0.003
0.005
0.005
0.005
0.005
0.004
0.007
0.010
0.006
0.002
0.005
0.005
0.003
0.006
0.000
0.006
Total Cr
g/L
0.66
0.68
0.82
0.84
0.89
0.98
0.77
1.03
0.94
13.45
12.78
13-09
14.22
12.47
13-15
13.45
12.14
12.77
26.46
27.82
24.54
23.17
24.34
23.04
23.72
21.67
19-97
52.28
62.39
8.34
57.19
60.37
61.95
53-39
58.56
52.78
Scrubber water drained into plating tank prior to
time this sample was taken.
3-16
-------
TABLE 3.8. ANALYTICAL RESULTS FOR HEXAVALENT AND TRIVALENT CHROMIUM
IN IMPINGER TRAINS
Run
No.
Date
(1986)
Sample Type
Total Catch
Cr -t-6
(mg)
Total Catch
Cr +3
(mg)
Total Catch
Total Cr
(mg)
Scrubber Inlet
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
1-10
i-ll
1-12
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
11.40
17-99
18.15
39-81
13.28
15.65
12.14
11.56
10.93
15.13
13.49
11.22
1.66
2.32
2.64
5.20
1.24
1.43
1.77
1.04
1.05
1.26
1.45
1.22
13.06
20.31
20.79
45.00
14.52
17.09
13-90
12.60
11.99
16.39
14.94
12.44
Scrubber Outlet
0-1
0-2
0-3
0-4
0-5
0-6
0-7
0-8
0-9
0-10
0-11
0-12
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
0.083
0.111
0.571
0.091
0.102
0.091
0.105
0.140
0.120
0.113
0.113
0.140
0.058
0.035
0.047
0.050
0.072
0.072
0.016
0.018
0.019
0.034
0.043
0.047
0.141
0.146
0.618
0.141
0.174
0.163
0.121
0.158
0.139
0.147
0.156
0.187
3-17
-------
the impinger or filter) were conducted through whichever port at each location
was not occupied by the impinger train. Since the Method 13~type impinger
train runs were two hours in duration, it was possible to conduct a personnel
sampling pump run first with the impinger for 30 minutes and then with the
filter for 30 minutes, without interferring with the impinger train run.
Detector tube measurements were made towards the end or directly following
each Method 13-type impinger train run, as time allowed. Both the detector
tube sample pump and an extra personnel sampling pump were used to draw samples
through the detector tubes.
Table 3-9 summarizes the analytical results for hexavalent and trivalent
chromium for the samples collected for the screening method tests using a
personnel sampling pump. The results for hexavalent chromium (assumed to be
all the soluble chromium) were obtained by the EPA draft method for hexavalent
chromium. The results for trivalent chromium (assumed to be all the insoluble
chromium) were obtained using ICAP to measure the chromium caught in a filtered
representative portion of the sample. Trivalent chromium was not analyzed for
the filter samples. Total chromium catches were calculated as discussed for
Table 3.8.
Table 3-10 presents a summary of the sampling parameters and chromium
emission results for each screening method run. Each of the sampling pumps
used was calibrated prior to the testing and the calibration values used to
calculate the actual flow rate during testing. All filter and impinger runs
were approximately 30 minutes in duration; exact sampling times are listed in
Table 3.10. The total volume of gas sampled was calculated by multiplying the
actual flow rate by the sampling time and correcting to standard conditions
(68 F and 29.92 in. Hg) using the barometric pressure and stack gas temperature
measured for the corresponding impinger train run. The catch weights of
chromium from Table 3-9 were then used to calculate the mass emission values
shown in Table 3-10. The following sections discuss the results for each
screening method in more detail. Comparative results are presented in Table
3.11.
3.5.1 Detector Tubes
The results for the detector tubes shown in Table 3-H indicate that they
are totally unacceptable as a screening method.
Detector tubes specific for a particular compound or element are used in
combination with a hand pump. The pump is designed to pull a precise volume
3-18
-------
TABLE 3.9.
ANALYTICAL RESULTS FOR HEXAVALENT AND TRIVALENT CHROMIUM
IN SCREENING METHOD SAMPLES
Run
No.
Date
(1986)
Sample
Type
Total Catch
Cr
ug
Total Catch
Cr
ug**
Total Catch
Total Cr
ug
Scrubber Inlet
I-l
1-2
1-3
1-4*
1-5
1-6*
1-7
1-8
1-9
1-10
1-11
1-12
I-l
1-2
1-3
1-4
1-5*
1-6
1-7
1-8
1-9
1-10
1-11
1-12
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
398.14
245.39
598.46
410.66
26.29
10.02
570.91
355.57
127.70
175.28
300.48
518.33
305.5
702.9
653.4
1.230.3
—
33.3
282.1
326.0
295.1
571.7
504.6
175.0
29.075
17.050
42.275
24.075
2.450
<0.25
36.125
23.850
6.900
7.850
19.125
32.475
427.22
262.44
640.74
434.74
28.74
10.02
607.04
379.42
134.60
183.13
319.61
550.81
Scrubber Outlet
0-1
0-2
0-3
0-4
0-5*
0-6
0-7
0-8
0-9
0-10
0-11
0-12
0-1
0-2
0-3
0-4
0-5
0-6
0-7
0-8
0-9
0-10
0-11
0-12
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
0.7
0.7
11.0
0.2
0.3
1.2
1.2
2.5
3.0
0.7
5.8
1.3
1.66
3.04
9.45
2.26
1.81
5.83
3.81
4.51
5.45
1.68
2.93
1.65
<0.25
0.350
<0.25
0.275
<0.25
<0.25
<0.25
<0.25
<0.25
<0.25
<0.25
<0.25
0.7
1.05
11.0
0.48
0.3
1.2
1.2
2.5
3.0
0.7
5.8
1.3
4(kRuns aborted or not conducted for technical reasons.
Due to dilution factors. 0.25 ug is the lower detection limit for this
analytical method.
3-19
-------
TABLE 3.10. SUMMARY OF SAMPLING PARAMETERS AND CHROMIUM EMISSION RESULTS
FOR SCREENING METHODS USING PERSONNEL SAMPLING PUMP
Run
No.
Date
(1986)
Sample
Type
Flow
Rate
L/min
Sampling
Time
min
Total Vol.
Sampled
L std
Mass Emissions
Cr+6
mg/'dscm
Total Cr
mg/dscm
Scrubber Inlet
1-1
1-2
1-3
1-4*
1-5
1-6*
1-7
1-8
1-9
1-10
1-11
1-12
1-1
1-2
1-3
1-4
1-5*
1-6
1-7
1-8
1-9
1-10
1-11
1-12
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
0.924
0.924
0.924
—
0.935
--
0.924
0.924
0.924
0.930
0.911
0.911
3.646
3.325
3.417
3.458
_-
3.602
3.602
3.602
3.602
2.617
2.617
2.477
30.0
30.0
29.5
--
32.0
--
31.0
34.0
29.5
30.0
60.6
40.0
30.0
30.0
27.0
30.0
--
40.0
32.0
35.0
37.5
30.0
35.0
32.0
26.66
26.67
26.23
—
29.09
--
27.89
30.37
26.30
27.32
53.71
35.44
105.68
96.02
88.82
100.72
--
140.15
112.29
121.91
128.71
76.91
89.23
77.06
14.93
9.20
22. 82
...
0.90
—
20.47
11 . 71
4.86
(,.42
!i.59
14.63
:>.89
7.32
7.36
12.22
...
0.24
;:.5i
;>.67
;>.29
7.43
!i . 66
:!.27
16.02
9.84
24.43
--
0.99
—
21.77
12.49
5.12
6.70
5.95
15.54
Scrubber Outlet
0-1
0-2
0-3*
0-4
0-5*
0-6
0-7
0-8
0-9
0-10
0-11
0-12
0-1
0-2
0-3
0-4
0-5
0-6
0-7
0-8
0-9
0-10
0-11
0-12
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
8/19
8/19
8/19
8/20
8/20
8/20
8/21
8/21
8/21
8/22
8/22
8/22
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Impinger
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
Filter
0.930
0.935
—
0.930
—
0.935
0.925
0.930
0.930
0.924
0.924
0.924
3.670
3.460
3.037
3.347
3.271
2.710
2.929
2.650
2.719
3.602
3.602
3.602
20.0
30.0
—
30.0
—
30.0
61.0
34.0
33.0
30.0
30.0
38.5
30.0
28.0
33.0
30.0
31.0
40.0
32.0
35.0
36.0
30.0
34.5
32.0
18.06
27.04
—
26.80
—
27.17
54.98
30.62
29.78
26.99
26.89
34.58
106.35
93.37
96.30
97.13
98.45
105.05
91.30
89.84
95.02
105.27
120.62
112.08
0.04
0.03
—
0.01
.._
0.04
0.02
0.08
0.10
0.03
0.22
0.04
0.02
0.03
0.10
0.02
0.02
0.06
0.04
0.05
0.06
0.02
0.02
0.01
0.04
0.04
—
0.02
--
0.04
0.02
0.08
0.10
0.03
0.22
0.04
Runs aborted or not conducted for technical reasons.
3-20
-------
TABLE 3.11. COMPARISON OF IMPINGER TRAIN AND SCREENING METHOD RESULTS
Run
No.
Impinger
Train
mg/dscm
Concentration of Hexavalent Chromium
and Relative Percent Difference from
Impinger Train Value
Screening Method
Impinger
mg/dscm
%
Filter
mg/dscm
%
Detector Tube
•a
mg/nr
%
Scubber Inlet
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
1-10
I-ll
1-12
4.50
7.0?
7.04
15.94
5.48
6.42
4.90
4.59
4.38
6.06
5.50
4.62
14.93
9.20
22.82
*
0.90
*
20.47
11.71
4.86
6.42
5.59
14.63
232
30
224
*
- 84
*
317
155
11
6
2
217
2.89
7.32
7.36
12.22
*
0.24
2.51
2.67
2.29
7-43
5.66
2.27
- 36
4
5
- 23
*
- 96
- 49
- 42
- 48
27
3
- 51
1.0
-86
*
- 94
*
- 69
*
- 91
- 89
- 84
- 70
- 57
Scrubber Outlet
0-1
0-2
0-3
0-4
0-5
0-6
0-7
0-8
0-9
0-10
0-11
0-12
0.022
0.028
0.146
0.023
0.028
0.025
0.030
0.039
0.034
0.032
0.032
0.039
0.039
0.026
*
0.007
*
0.044
0.022
0.082
0.101
0.026
0.216
0.038
79
- 6
*
- 68
*
75
- 28
108
199
- 19
572
- 5
0.016
0.033
0.098
0.023
0.018
0.055
0.042
0.050
0.057
0.016
0.024
0.015
- 28
18
- 33
0
- 33
120
38
28
70
- 50
- 24
- 63
0.1
0.15
0.1
<0.1
<0.1
<0.1
0.017
*
*
0.02
0.02
0.03
362
445
- 32
>328
>262
>295
- 44
*
*
- 37
- 38
- 24
*Runs not conducted, aborted, or data not valid (see text).
3-21
-------
of gas sample through a detector tube. The compound of interest in the air
reacts with the reagent(s) in the tube which affects a color change indicating
the concentration of the compound by stain length or depth of coloration. The
number of pump strokes is specified for the tube to read in the range of
concentrations for which a tube is designed. In some cases, as was done for
this testing, the number of stokes may be increased or decreased to test
concentrations outside this range.
In general, detector tubes are designed to measure low concentrations of a
compound in ambient air. In the case of chromic acid testing, when the sample
concentrations drawn through the tubes were in excess of the indicating
capacity of the tubes, they often gave an indication representative of a lesser
concentration. Determining the exact color of a tube was also a problem. Many
times the color was between or lighter than the colors of the color comparison
tube. In addition, the color indication band on the chromic acid tubes begins
to fade within 15 to 30 minutes of sampling. Therefore, they could not be
submitted to a responsible party for confirmation of the results.
To use detector tubes as a screening method, it would be necessary to know
the approximate concentration of the gas being measured to be able to gauge the
number of pump strokes required to obtain a reading. In many cases, this
information would not be readily available. Therefore, numerous tubes would
have to be run to bracket the number of pump strokes required. Based on the
lack of reproducibility and accuracy shown in this test series, this procedure
would be difficult at best. Any variations in process rate during the
bracketing would cause additional difficulty.
As the chromic acid concentration of the gas being measured decreases, the
number of pump strokes required for an indication increases. Some of the tube
readings taken on this test required more than 100 pump strokes. Because of
the rate of sample passage through the packing in the tube, the time required
for one pump stroke is approximately 10 seconds. This means that 100 pump
strokes require about an hour to accomplish. This would easily cause operator
fatigue, particularly since it is highly likely that more than one tube reading
would be necessary.
Based on the results and experience from this test and additional work by
both EPA and EPA contractor personnel (see the EPA memo in Appendix C), the
detector tubes are not considered a viable screening technique for this
application.
3-22
-------
3«5.2 Filter and Personnel Pump Train
The results of sampling with the filter and personnel pump presented in
Table 3.11 suggests that this method may be acceptable. Most of the measured
values from the filter screening method were within 50% of the impinger train
value.
As demonstrated by the data in Table 3-12, almost all of the sample was
collected in the nozzle and probe portions of the train. The precision of this
screening method would probably improve and be within an acceptable range if
one of two modifications was made. The first would involve using the existing
train and improving the probe cleaning (sample recovery) technique. The second
(and probably better) modification would involve eliminating the probe and
using the filter cassette in-stack with only a nozzle in front of it. This
method would result in a greater proportion of the catch on the filter and
would yield less surface area from which to recover the sample.
This screening method could be used as is, but the precision would
probably improve with the addition of one of the above mentioned modifi-
cations. In addition, the method can be readily performed by any individual
skilled in plant maintenance or laboratory operations.
3.5-3 Impinger and Personnel Pump Train
The results shown in Table 3.11 for the single impinger and the personnel
pump train would generally be considered too imprecise; to be used as a
screening method. The precision of the method could probably be improved by
modifying the sampling procedures to include better probe cleaning techniques.
The main reason for the imprecision is probably the same as for the filter
train, that most of the sample is collected in the nozzle and probe. Due to
the size of the impinger and the fact that it must be maintained in an upright
position, it would not be advantageous to remove the p>robe from the train and
sample with the impinger in the stack.
The impinger and personnel pump train as a screening method did not demon-
strate any advantage over the filter train. In fact, it would require greater
skill to operate and should therefore only be considered a weak alternative to
the filter train system.
3-23
-------
TABLE 3.12. COMPARISON OF CHROMIUM CATCH ON FILTER VS. IN PROBE RINSE
Run
I-l-F
I-2-F
I-3-F
I-4-F
I-5-F
I-6-F
I-7-F
I-8-F
I-9-F
I-10-F
I-ll-F
I-12-F
Average
0-1-F
0-2-F
0-3-F
0-4-F
0-5-F
0-6-F
0-7-F
0-8-F
0-9-F
0-10-F
0-11-F
0-12-F
Average
Percentage of Total Hexavalent Chromium Catch
Filter
0.16%
0.56%
0.06%
0.03%
0.30%
o.o4%
0.03%
0.04%
0.13%
0.32%
2.85%
0.41%
8.76%
29.63%
9.90%
26.17%
13.72%
7.20%
14.63%
28.38%
11.49%
5-62%
3-30%
5.71%
13.71%
Probe
99.84%
99.44%
99.94%
99.97%
—
99.70%
99.96%
99-97%
99-96%
99.87%
99.68%
97.15%
99.59%
91.24%
70.37%
90.10%
73-83%
86.28%
92.80%
85-37%
71.62%
88.51%
94.38%
96.70%
94.29%
86.29%
3-24
-------
4.0 SAMPLING LOCATIONS AND TEST METHODS
This section describes the sampling locations and test methods used to
characterize emissions from the hard chromium plating tanks at Piedmont
Industrial Plating Company in Statesville, North Carolina. Five sampling
locations were used in the emissions testing program. At two sampling
locations (one at the scrubber inlet and one at the scrubber outlet), emissions
testing was conducted for hexavalent and total chromium using a Method-13 type
impinger train. Total chromium content was calculated as the sum of the
hexavalent and trivalent chromium. At the large and small plating tank
locations, grab samples were taken at the middle of each sampling run. Three
grab samples per sampling run were collected from the fifth location, the
scrubber recirculating water reservoir. All grab samples were analyzed for
hexavalent and trivalent chromium concentrations. The relative positions and
the type of testing conducted at each location are shown in the simplified
process flow diagram (see Figure 4.1) and accompanying Table 4.1. The
subsections that follow further describe each sampling location and applicable
test methods.
4.1 SCRUBBER INLET (SAMPLING LOCATION A)
Hexavalent chromium and total chromium emissions were measured at the inlet
to the scrubber, as shown in Figure 4.2. Two sampling ports were installed
90 apart in the horizontal circular duct (27 inches in diameter). These ports
were located 8.8 inches (0.33 duct diameters) upstream of a bend in the duct to
the scrubber and 55-2 inches (2.04 duct diameters) downstream from another
bend.
For the Method 13-type impinger train testing (refer to Appendix C for
further discussion of sampling train and sample analysis procedures), a total
of 24 points as per Method 1, were sampled. Each of the 24 points was sampled
for 5 minutes for a total of 120 minutes of sampling per run. Each run was
performed concurrently with sampling at the scrubber outlet location.
4-1
-------
If
4=-
I
I.D.
FAN
DUALL
SINGLE
PACKED-BED
SCRUBBER
C
WALL
t
i
t--
r
x HOODS :
23-FOOT TANK
t
^
^
LEGEND:
AIRFLOW
WALL
t
S^^^HOQDS^^
i
\V
10-FOOT TANK
E
FIGURE 4.1. SCHEMATIC OF AIRFLOW AND SAMPLING LOCATIONS.
-------
TABLE 4.1. SAMPLING PLAN FOR PIEDMONT INDUSTRIAL PLATING COMPANY
Sample Type
Sampling
Locations
Number
of Samples
Methods*
Standards Setting
Hexavalent Cr
Total Cr
Hexavalent &
Total Cr
A & B
A & B
C
D
E
12 each
12 each
12 sets of 3 grab
12 grab
12 grab
Method 13 -Type Impinger
Train ^Tentative Method
for Cr*6
Method 13-Type Impinger
Train & ICP Analysis for
Cr 5
Tentative EPA Method
for Cr & ICP for Cr+:>
Screening Methods Development
Hexavalent &
Total Cr
Hexavalent &
Total Chromium
Chromic Acid
A & B
A & B
A & B
12 each
12 each
Personnel Monitoring Pump
with Midget Impinger and
Tentative EPA Method- for
Cr and ICP for Cr"^
Personnel Monitoring Pump
with Teflon Filter and
Tentative EPA Method for
Hexavalent Cr
Detector Tubes
ICP: Inductively-Coupled Argon Plasmography
4-3
-------
27" DIA.
TRAVERSE POINTS
2 AXES
12 POINTS/AXIS
24 POINTS TOTAL
SECTION M-M
I *• M
A
O
•8.8'
69"
55.2"
AIR FLOW
FIGURE 4.2. PIEDMONT INDUSTRIAL PLATING COMPANY: SCRUBBER INLET.
-------
4.2 SCRUBBER OUTLET (SAMPLING LOCATION B)
Hexavalent chromium and total chromium emissions were measured at the
scrubber outlet as shown in Figure 4.3- Two sampling ports were installed 90
apart in the vertical circular stack (24 inches in diameter). These ports
were located 14 inches (0.58 duct diameters) upstream from the stack exit and
56 inches (2.33 duct diameters) downstream from the fan.
For the Method 13~type impinger train testing (refer to Appendix C for
further discussion of sampling train and sample analysis procedures), a total
of 2k points as per Method 1, were sampled. Each of the 24 points was sampled
for 5 minutes for a total of 120 minutes of sampling per run. Each run was
performed concurrently with sampling at the scrubber inlet location.
4.3 SCRUBBER RECIRCULATION WATER RESERVOIR (SAMPLING LOCATION C)
During each sampling run, three grab samples of the scrubber recirculation
water were taken from the scrubber reservoir (Sampling Location C). The
samples were analyzed for hexavalent and trivalent chromium concentrations.
The chromium concentration of the scrubber recirculation water was varied prior
to each day's testing by transferring a pre-determined volume of plating
solution from the plating tanks into the scrubber reservoir. Three
simultaneous inlet and outlet emission sampling runs were performed at each of
the four scrubber water chromium concentrations.
4.4 PLATING TANK SOLUTIONS (SAMPLING LOCATIONS D AND E)
At the middle of each sampling test run, grab samples of the plating tank
solution of both the 23-foot (Sampling Location D) and! 10-foot (Sampling
Location E) tanks were collected. The samples were analyzed for hexavalent and
trivalent chromium concentrations.
4.5 VELOCITY AND TEMPERATURE
A type S pitot tube and magnehelic gauges were used to measure the gas
velocity pressure (delta P). Velocity pressures were measured at each sampling
point across the duct or stack to determine an average value according to the
procedures outlined in Method 2. The temperature at each sampling point was
measured using a thermocouple and digital readout.
-------
24"DIA.-H
TRAVERSE POINTS
2 AXES
12 POINTS/AXIS
24 POINTS TOTAL
24- DIA.
t
14'
M
56'
B A
00
70"
I.D.FAN
B A
SECTION n-M
FIGURE 4.3. PIEDMONT INDUSTRIAL PLAT ING COMPANY: SCRUBBER OUTLET.
4-6
-------
4.6 MOLECULAR WEIGHT
The flue gas composition and molecular weight were; assumed to be those of
ambient air.
4.7 SAMPLING TRAINS
Hexavalent Chromium and Total Chromium - A Method 13~type impinger train
was used to capture chromium emissions at Sampling Locations A and B. All
tests were conducted isokinetically by traversing the cross-sectional area of
the duct or stack and regulating the sample flow rate relative to the flue gas
flow rate as measured by the pitot tube attached to the sample probe. The
sampling train consisted of a heated, glass-lined probe, a filter bypass, four
impingers (the first two containing 100 ml of 0.1N NaOH each and the fourth
containing silica gel). Previous test programs using Method 13~type trains
have shown greater than 99$ hexavalent and total chromium collection prior to a
back half filter. As a result, this test program optesd to omit the use of a
filter in the sampling train. A deionized water rinse of the nozzle, probe,
and first three impingers was made at the end of each test.
Personnel Monitoring Pump - Personnel monitoring pump sampling was
performed twice per run concurrent with the impinger train runs. During each
120-minute impinger train sampling run, two 30 to 45 minute personnel
monitoring pump sampling runs were performed, one using a midget impinger
containing 15 ml of 0.1N NaOH and one using a 37-mm Teflon filter for
collecting the chromium emissions. Sampling was conducted at both the inlet
(Sampling Location A) and the outlet (Sampling Location B) of the packed-bed
scrubber. The sampling trains consisted of a 2-1/2 foot Teflon tube-lined
probe, the midget impinger or filter cassette with a Teflon filter, and the
personnel sampling pump. The pump was set to sample at 1.0 liter per minute
for the impinger runs and 3-5 to 4.0 liters per minute for the filter runs.
All samples were analyzed for hexavalent chromium content; midget impinger
samples were also analyzed for trivalent chromium content.
Detector Tube Sampling - Detector tube sampling was performed during or
immediately following each impinger train run. Samples were collected at both
Sampling Locations A and B using a Draeger™ pump and Draeger chromic acid
detector tubes following the manufacturer's instructions. In cases where
4-7
-------
greater than 200 pump strokes were required to elicit an indication on the
detector tube, a personnel sampling pump was used to draw the stack gas through
the tube.
4.8 HEXAVALENT CHROMIUM CONTENT
Hexavalent chromium content was determined utilizing procedures described
in the tentative EPA Method "Determination of Hexavalesnt Chromium Emissions
from Stationary Sources" (see Appendix C); the assumption was made that all
soluble chromium was in the hexavalent state. At the end of each Method
13~type impinger train run, the impinger reagent and train rinsings were
combined into one sample which was analyzed for hexavalent chromium content
using this method. This method was also used to determine the hexavalent
chromium content in the process grab samples and in the personnel monitoring
pump samples (impinger and filter samples) that were collected.
4.9 TRIVALENT CHROMIUM CONTENT
Trivalent chromium content was determined using Inductively Coupled Argon
Plasmography (ICP) (see Appendix C); the assumption was made that all insoluble
chromium was in the trivalent state. Portions of each impinger and each
process sample were initially filtered. Then the filters were nitric acid-
digested and the digestate was analyzed for chromium by RTI using ICAP. Total
chromium contents of the impinger samples, process samples, and midget impinger
samples were calculated using the analytical results for hexavalent chromium
and trivalent chromium.
4-8
-------
5.0 QUALITY ASSURANCE
Because the end product of testing is to produce representative emission
results, quality assurance is one of the main facets of stack sampling.
Quality assurance guidelines provide the detailed procedures and actions
necessary for defining and producing acceptable data. Two such documents
were used in this test program to ensure the collection of acceptable data
and to provide a definition of unacceptable data. These documents are: the
EPA Quality Assurance Handbook Volume III, EPA-600/4-77-027 and Entropy's
"Quality Assurance Program Plan" which has been approved by the U.S. EPA,
EMB.
Relative to this test program, the following steps were used to ensure
that the testing and analytical procedures produced quality data.
• Calibration of field sampling equipment. (Appendix D describes
calibration guidelines in more detail.)
• Checks of train configuration and on calculations.
• On-site quality assurance checks such as sampling train, pitot tube,
and quality assurance checks of all test equipment prior to use.
• Use of designated analytical equipment and sampling reagents.
Table 5.1 summarizes the on-site audit data sheets for the sampling
equipment used for the testing at each sampling location, including deviation
limits. In addition to the pre- and post-test calibration audits, a field
audit was performed on the meter boxes used for sampling. Entropy used the
procedures described in the December 14, 1983 Federal Register (48FR55670).
Appendix D includes the audit run data sheets for each dry gas meter used for
the testing and audit data sheets for the other sampling equipment.
Audit samples prepared by Entropy were used to check the analytical
procedures of the laboratory conducting the hexavalent and trivalent chromium
analyses. One of these samples was a hexavalent chromium solution (QA-2).
the other sample was prepared by passing a hexavalent chromium solution
through the same type of filter used to collect trivalent chromium. This was
done to confirm that only trivalent chromium would be collected. Table 5.2
5-1
-------
TABLE 5.1. FIELD EQUIPMENT CALIBRATION
Equipment
Reference
Allowable
Error
Actual
Error
Within
Allowable
Limits
Scrubber Inlet
Meter box (N-6)
Meter box thermometer
Impinger thermometer
Stack thermometer
Wet test meter
ASTM-3F at ambient
temparture
ASTM-3F at ambient
temperature
ASTM-3F at ambient
temperature
Y +_ 0.03Y
5°F
2 °F
7°F
0.0115
1 °F
0°F
0°F
Scubber Outlet
Meter box (N-8)
Meter box thermometer
Impinger thermometer
Stack thermometer
Wet test meter
ASTM-3F at ambient
temperature
ASTM-3F at ambient
temperature
ASTM-3F at ambient
temperature
Y + 0103Y
5°F
2 °F
7°F
0.0137
0 °F
2 °F
3°F
(/
^
-------
presents the results of these analytical audits; they indicate that the
analytical techniques were accurate.
The sampling equipment, reagents, and analytical procedures for this test
series were in compliance with all necessary guidelines set forth for accurate
test results as described in Volume III of the Qualitj' Assurance Handbook.
5-3
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TABLE 5.2. AUDIT REPORT CHROMIUM ANALYSIS
Plant:
Date Samples Received:
Samples Analyzed By: f o*t
titter
/Mi/HdCrV
iMilfrlC^
Source of
Sample
QAD/^&C
Q.AI>
C^A-D
Analytical.
Technique
. rof>
roe
Cr-*-
Audit
Value
O-O
1.03
/.Ol
Relative
Error, %
0-0
-hZ.6
/-/.£>
5-4
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