p.1 

OAR Box 1313 

Prepped by LaTeia Shed 

Document Number: 

52) ll-B-26 

Docket Number: 

A-88-02 

Printed 6/12/2008 9:03:29 AM Sheet 52 of 99 
® 

7 7X5 .Qh

 ''•! ! 

.••-. JAN I 81991 ll'i i 

P.2 

A-88-02 

MIDWEST RESEARCH INSTITUTE 

Suite 350 

401 Harrison Oaks Boulevara 

Cary, North Carolina 27513 

Telephone (919) 467-5215 

Facsimile (919) 467-8060 

i

 r5C"5}5 DOCKET 

Date: May 15, 1987 <-_-.--- — *~—~ 

(Finalized December 8, 1987) 

Subject: Engineering Analysis—Reliable Plating & Polishing Company 

Chromium Electroplating NESHAP 

EPA Contract 68-02-3817; ESED Project 85/02a 

MRI Project 7717-K 

From: Robin Barker r& 

To: Al Vervaert 

ESED/ISB/SSS (MD-13) 

U. S. Environmental Protection Agency 

Research Triangle Park, NC 27711 

I. Purpose 

On .April 1, 1987, testing was conducted on a scrubber used to control 

chromic acid emissions from one anodizing tank at Reliable Plating and 

Polishing Company, Inc. (Reliable) in Bridgeport, Connecticut, to estimate 

the amount of uncontrolled chromium emissions from the process. The 

purpose of this memorandum is to (1) present the results of these tests, 

(2) compare the estimated chromium emissions from Reliable to chromium 

emission results from an emission test at another anodizing facility; and 

(3) compare the estimated emissions from Reliable to emission test data 

for hard and decorative chromium electroplating facilities. 

II. Background 

Reliable is a small job shop that performs chromic acid anodizing of 

aircraft and electronic parts. The anodizing tank at Reliable is equipped 

with a Niehaus fume scrubber. The scrubber system does not contain a 

recirculation unit. The once-through scrubber water is combined with 

other effluent streams and is treated in a wastewater treatment system. 

During a visit to the plant, chromic acid was visible across the 

surface of the solution only during the first 5 to 10 minutes of the 

anodizing cycle, when the voltage was stepped up to 40 volts. Stepping 

the voltage causes an initial current surge that generates hydrogen and 

oxygen gas that breaks through the surface of the solution entraining 

chromic acid which results in the misting. Thereafter, the voltage is 

maintained at 40 volts, and the amperage drops off significantly; no 

misting was observed across the surface of the solution for the remainder 

of the anodizing cycle. A trip report documenting the details of the 

anodizing process and its associated air pollution control equipment is 

presented in Attachment 1. 

/ 
P.3 

III. Sampling Procedures 

The testing consisted of obtaining composite samples representative 

of the scrubber influent, scrubber effluent, and anodizing solution for 

each of four l-hour anodizing cycles. Each sample consisted of four grab 

samples that were collected approximately 15, 30, 45, and 60 minutes into 

each anodizing cycle. The sampling locations are shown in Figure 1 and 

are designated as letters A, B, and C. The composite samples obtained 

during the tests were analyzed for both hexavalent and total chromium. 

The scrubber water flow rate also was measured periodically by 

placing an 18.9-liter (5-gallon) container in the outlet stream and 

recording the amount of time required to fill the container. The temperature, operating voltage, and operating current of the anodizing solution; 

the number and types of parts anodized during each anodizing cycle; and 

the outlet water flow rate of the scrubber were recorded during each 

anodizing cycle. These data are presented in Attachment 2. 

IV. Results of Mass Balance 

The results of the sample analyses were used to perform a chromium 

mass balance around the scrubber to estimate uncontrolled chromium 

emissions. The analytical results for each composite sample are presented 

in Table 1. The analytical results show that all of the chromium in the 

outlet scrubber water was in the hexavalent state. 

The following equation was used to solve for the uncontrolled 

chromium mass emission rate: 

M = [(Qw)(Cw)]/E (1) 

where, M = uncontrolled chromium mass emission rate, kg/h (lb/h); 

Qw = outlet water flow rate of scrubber, a/h (gal/h);. 

Cw = chromium concentration of outlet water stream, kg/a (lb/gal); 

and 

E = efficiency of the scrubber, 90 percent. 

The derivation of the above equation is presented in Attachment 3. 

The uncontrolled chromium emission rate was calculated using a 

scrubber efficiency of 90 percent. Previous source tests at chromium 

electroplating facilities showed that the efficiency of packed-bed 

scrubbers ranged from 93 to 99 percent. The vendor of the Niehaus fume 

scrubber states that it can achieve an efficiency of 95 to 99 percent. 

However, the conservative estimate of 90 percent efficiency was used in 

these analyses because it is expected that the fume scrubber is less 

efficient than a packed-bed scrubber. An example calculation of the 

uncontrolled chromium emission rate is also presented in Attachment 3. 

The estimated uncontrolled chromium emission results and workload 

descriptions for each test run are presented in Table 2. The uncontrolled 

5L 
DRAIN 

VENTILATION 

HOODS 

-**> 

LEGEND AIRFLOW 

_> -^. 

-5 

-*r y 

ANODIZING c 

TANK 

COMPOSITE SAMPLE LOCATIONS 

A = WATER STREAM INLET 

B = WATER STREAM OUTLET 

C = ANODIZING SOLUTION 

AIR STREAM OUTLET 

•* 

i 

I 

WATER STFlEAM OUTLET 

g. l_ 

AIR STREAM 

INLET 

SCRUBBER 

— A 

^ WATER 

STREAM 

INLET 

Figure 1. Schematic of chromic acid anodizing tank and Niehaus fume scrubber at Reliable 

Plating Company in Bridgeport, Connecticut. 

0> 
P.5 

TABLE 1. ANALYTICAL RESULTS OF COMPOSITE SAMPLES TAKEN DURING 

EACH TEST RUN AT RELIABLE PLATING AND POLISHING 

COMPANY IN BRIDGEPORT, CONNECTICUT 

Sample description Run No. 

Sample concentration, ug/ma (oz/gal) 

Hexavalent Total 

chromium chromium 

Outlet scrubber water 

Inlet scrubber water3 

Anodizing bath 

1 

2 

3 

4 

AVERAGE 

1 

2 

3 

4 

AVERAGE 

1 

2 

3 

4 

AVERAGE 

3.9 (5.2x107) 

0.8 (1.1x10,) 

0.3 (4.0xl0~*) 

5.1 (6.8xl0~ ) 

2.5 (3.3x10"") 

<0.1 (0) 

<0.1 (0) 

<0.1 (0) 

<0.1 (0) 

<0.1 (0) 

50,300 (6.72) 

50,500 (6.74) 

50,700 (6.77) 

50,300 (6.72) 

50,450 (6.74) 

3.9 (5.2xlO"J 

0.8 (1.1x10',) 

0.3 (4.0x10,) 

5.1 (6.8x10 ) 

2.5 (3.3xl0_lf) 

<0.1 (0) 

<0.1 (0) 

<0.1 (0) 

<0.1 (0) 

<0.1 (0) 

52,000 (6.94) 

51,900 (6.93) 

51,100 (6.82) 

50,300 (6.72) 

51,325 (6.85) 

aThe amount of chromium in the inlet water stream was below the detectable 

limit of the analytical procedure (0.1 ug/ma) and was assumed to be equal 

to zero. 

f 
P.6 

TABLE 2. UNCONTROLLED CHROMIUM MASS EMISSION RATES BASED ON HEXAVALENT 

ANO TOTAL CHROMIUM CONCENTRATION OF OUTLET SCRUBBER WATER 

Run No. 

1 

2 

3 

4 

Average 

Uncontrolled chromium 

emission rate at 

scrubber efficiency of 

90 percent, kg/h (lb/h)a 

0.0019 

(0.0042) 

0.00039 

(0.00086) 

0.00015 

(0.00033) 

0.0025 

(0.0055) 

0.0012 

(0.0026) 

No. of parts 

or racks 

anodized 

14 racks 

22 parts 

16 parts 

17 racks 

Type of part 

anodized 

Small aircraft and 

electronic parts 

Aircraft parts 

Aircraft parts 

Small aircraft and 

electronic parts 

aTotal and hexavalent chromium concentrations in scrubber water were 

equal. 

m ^ 
P.7 

chromium emission rate3ranged from 1.5x10" kg/h (3.3xl0~4 lb/h) to 

2.5x10" kg/h (5.5x10" lb/h). The variation in the estimated 

uncontrolled chromium emission rates is directly related to the total 

surface area and configuration of the parts anodized during each test 

run. The same type of aircraft parts was anodized during run Nos. 2 and 3 

with 22 parts anodized during run No. 2 and 16 parts anodized during run 

No. 3. The workload decreased 27 percent from run No. 2 to run No. 3 with 

a subsequent decrease of 61 percent in the uncontrolled emission rate. 

The types of parts anodized during both run Nos. 1 and 4 were similar and 

consisted of racks of small aircraft and electronic parts with 14 racks of 

parts anodized during run No. 1 and 17 racks of parts anodized during run 

No. 4. The workload increased 18 percent from run No. 1 to run No. 4 with 

a subsequent increase of 24 percent in the uncontrolled chromium emission 

rate. 

Th§ average uncontrolled emission rate for run Nos. 2 and 3 is 

2.7x10" kg/h (5.9x10" lb/h), and the average3uncontrolled emission rate 

for run Nos. 1 and 4 is 2.2x10" kg/h (4.9x10" lb/h). The average of run 

Nos. 2 and 3 is only 12 percent of the average of run Nos. 1 and 4, which 

suggests that both total surface area and configuration of the parts 

substantially affect the amount of uncontrolled emissions. 

The average uncontrolled chromium emission rate for all four runs was 

1.2x10" kg/h (2.6x10" lb/h). Even though the data show a wide range of 

uncontrolled emission rates due to the different workloads during each 

run, it is reasonable to average the estimated emissions because workload 

variations are common for the industry. 

V. Discussion 

The estimated uncontrolled chromium emission rates for Reliable were 

compared to test data obtained from Douglas Aircraft Company (Douglas 

Aircraft), in Torrance, California, to determine if the estimated emission 

rates for Reliable were similar to those obtained from another anodizing 

operation. Three emission test runs were conducted at Douglas Aircraft 

at the inlet and outlet of a scrubber controlling chromic acid emissions 

from one large anodizing tank. Standard EPA Method 5 sampling trains were 

used at each test location. 

The anodizing tank at Douglas Aircraft was operating at a full 

workload during only the third emission test run, and sampling was 

conducted only when parts were in the tank. Therefore, the estimated 

emission rates for Reliable were compared only to the emission rates 

obtained during the third emission test run at Douglas Aircraft. Table 3 

presents the test results and process parameters for Reliable and Douglas 

Aircraft. The uncontrolled hexavalent chromium emission rate at Douglas 

Aircraft was 2.8x10" kg/h (6.2x10" lb/h). The hexavalent chromium 

emission rate is similar to the highest estimated chromium emission rate 

(2.5x10 kg/h or 5.5x10" lb/h) obtained at Reliable. 

The uncontrolled chromium emission rates from Reliable were also 

compared to controlled emission rates from hard and decorative chromium 
P.8 

TABLE 3. COMPARISON OF TEST RESULTS AND PROCESS PARAMETERS 

BETWEEN RELIABLE AND OOUGLAS AIRCRAFT 

Reliable 

Douglas 

Aircraft 

Uncontrolled emission rate, 

kg/h (lb/h) 

High value 

Low value 

Average 

Workload description 

Types of parts 

Capacity 

Tank parameters 

Number of tanks 

Dimensions (1, w, d) , m (ft) 

2 2 

Surface area, m (ft ) 

Capacity, a (gal) 

Operating voltage, stepwise (v) 

0.0025 

(0.0055) 

0.00015 

(0.00033) 

0.0012 

(0.0026) 

Aircraft and 

electronic 

Full 

1 

3.5, 0.61, 0.91 

(11.5, 2.0, 3.0) 

2.14 

(23.0) 

1,893 

(500) 

40 

0.0028 

(0.0062) 

Aircraft 

Full 

1 

9.4, 1.1, 2.2 

(31.0, 3.7, 7.3) 

10.59 

(114) 

17,557 

(4,638) 

20 

/ 
P.9 

8 

plating tanks when either fume suppressants, mist eliminators, or packedbed scrubbers were used as the primary control technique to control 

chromic acid misting. The average controlled total chromium emission 

rates were 2.2x10" kg/h (4.8x10" lb/h) for fume suppressants, 

2.5x10" 3kg/h (5.5x10" lb/h) for mist eljminators, and 1.23x10" kg/h 

(2.7x10" lb/h) for packed-bed scrubbers. 

Table 4 presents the comparison of uncontrolled emissions from 

Reliable to controlled emissions from electroplating operations. The 

average of the two lowest uncontrolled chromiym emission rates (run Nos. 2 

and 3) at Reliable was 2.7x10" kg/h (5.9x10' lb/h), which is 19 percent 

higher than the controlled chromium emission rate for decorative chromium 

electroplaters with a fume suppressant as the primary control technique. 

The highest uncontrolled chromium'emission rate, 2.5x10" kg/h 

(5.5x10" lb/h), obtained at Reliable during run No. 4, is equal to the 

average controlled chromium emission rate from hard chromium electroplaters with mist eliminators as the primary control device. The average 

uncontrolled chromium emission rate at Reliable, 1.2x10" kg/h (2.6x10" 

lb/h), is approximately equal to the average controlled chromium emission 

rate from hard chromium electroplaters with packed-bed scrubbers as the 

primary control device. 

1 
P.10 

TABLE 4. COMPARISON OF UNCONTROLLED EMISSION RATES AT RELIABLE TO 

CONTROLLED EMISSION RATES FROM ELECTROPLATING OPERATIONS 

Emission rates, 

kg/h (Ib/h) Reliable 

Decorative chromium 

plating 

Fume suppressant 

with estimated 

control efficiency 

of 90*a 

Hard chromium plat In 

Mist eliminators 

with control 

efficiencies of 

87-98*° 

ked-b 

scrubbers 

with control 

efficiencies 

of 93-99*c 

High value 

Low value 

Average of alI runs 

0.0025 

(0.0055) 

0.000t5 

(0.00033) 

0.0012 

(0.0026) 

0.000219 

(0.000484) 

0.0038 

(0.0084) 

0.0012 

(0.0026) 

0.0025 

(0.0055) 

0.00167 

(0.0037) 

0.000719 

(0.0016) 

0.00123 

(0.0027) 

Average of run 

Nos. 2 and 3 

at Rel iable** 

0.00027 

(0.00059) 

j*Data obtained from one emission test conducted at a decorative chromium plating operation. 

Data obtained from average of two emission tests conducted at hard chromium plating 

operations. 

*:Data obtained from average of three tests conducted at hard chromium plating operations. 

Oata used for comparison of uncontrolled emission rates from Reliable to controlled emission 

rates from decorative chromium plating operation with a fume suppressant used as the primary 

control technique. 
p.11 

10 

VI. References 

1. Chromium Electroplaters Test Report: McDonnell Douglas Aircraft 

Company, Torrance, California. Engineering-Science, Pasadena, 

California. Source Emission Testing of Tank 193 and Tank 195 at 

Douglas Aircraft Company, Torrance, California. October 1-3, 1986. 

November 12, 1986. p. 5. 

2. Background Information Document, Chromium Electroplating NESHAP, Draft 

Chapter 4. U. S. Environmental Protection Agency. Research Triangle 

Park, North Carolina, p. 4-56. 

3 Attachments 

/O 
P.12 

Attachment I 

& 

MIDWEST RESEARCH INSTITL 

•"505 Creeamocr fi 

Raieign. N.C 2'. 

Teleonone (919) 781-' 

Date: March 16, 1987 

(Finalized April 2, 1987) 

Subject: Site Visit—Reliable Plating Company 

Chromium Electroplating NESHAP 

EPA Contract 68-02-3817; ESED Project 85/02a 

MRI Project 7717-K 

From: Robin Barker 

To: Al Vervaert 

ESED/ISB/SSS (MD-13) 

U. S. Environmental Protection Agency 

Research Triangle Park, N.C. 27711 

I. Purpose 

The purpose of this site visit was to gather background information 

about the chromic ad d anodizing operation at this plant and to assess 

visually the amount of misting from the chromic acid anodizing tank. 

II. Place and Date 

Reliable Plating and Polishing Company, Inc. 

Post Office Box 4217 

80 Bishop Avenue 

Bridgeport, Connecticut 06607 

(203) 366-5261 

December 18, 1986 

III. Attendees 

Reliable Plating Company 

Bob Morris, Plant Maintenance 

Auggie Dattolo, Process Engineer 

U. S. Environmental Protection Aqency (EPA) 

Al Vervaert, ISB 

Midwest Research Institute 

Robin Barker 

/( 
P.13 

IV. Discussion 

The plant visit began with a discussion about the chromic acid 

anodizing operation. The discussion was followed by a tour of the 

facility. 

A. General 

Reliable Plating Company is a job shop engaged primarily in chromic 

a d d anodizing of aircraft and miscellaneous parts. Decorative chromium 

plating and other plating operations are also performed at this plant. 

Reliable Plating Company is a certified United States military 

contractor. The plating shop 1s operated 8 hours per day, 5 days per 

week. 

B. Process Description 

The one chromic ad d anodizing tank at this facility 1s configured 

as shown in Figure 1. The chromic acid anodizing process consists of the 

following steps: alkaline cleaning, cold water rinse, nitric acid dip, 

cold water rinse, anodizing, and nickel acetate sealing and/or hot water 

sealing. The aluminum frequently 1s dyed after sealing. The anodizing 

H n e 1s equipped with an automatic hoist to transfer parts Into and out of 

the process tanks. 

The anodizing solution contains chromic acid 1n a concentration of 

approximately 60 to 75 grams per Uter (8 to 10 ounces per gallon) of 

water. The operating temperature ranges from 35° to 38°C (95° to 100°F). 

The anodizing tank 1s 3.5 meters (m) (11.5 feet (ftl) long, 0.61 m 

(2.0 ft) wide, and 0.91 m (3.0 ft) deep and has a capacity of approximately 1,893 liters (500 gallons) of anodizing solution. The tank 1s 

equipped with a 4,000-ampere rectifier. The voltage is applied step-wise 

until a level of 40 volts is reached. This level is applied for the 

remainder of the anodizing time. The current typically ranges from 200 to 

300 amperes, and the anodizing time is approximately 1 hour. 

C. Emission Control 

The anodizing tank is equipped with a double-sided draft hood to 

capture the chromic ad d mist. The ventilation hood is ducted to a wet 

scrubber manufactured by Neihaus Brothers, Inc. The scrubber is located 

adjacent to the anodizing tank. 

The Niehaus scrubber is a fume exhaust and separating unit developed 

primarily for the electroplating and chemical industries. The scrubbing 

action is achieved by a combination of water absorption and centrifugal 

separation. Figure 2 1s a schematic of the Niehaus scrubber. Its 

operation is described by Niehaus as follows: 

/£ 
DRAIN 

- > ->*>• 

LEGEND AIRFLOW 

VENTILATION 

HOODS 

AIR STREAM OUTLET 

EAM 

AIR STREAM 

INLET 

SCRIBBI.K 

Figure 1. Schematic of chromic acid anodizing tank. 

15 
P.15 

WATER INLET 

. INTAKE STACK 

SPRAY CHAMBER 

SEPARATING 

CHAMBER 

BLOWER 

DRAIN 

OUTLET 

Figure 2. Centrifugal-flow scrubber manu 

factured by Niehaus Brothers, Inc. 

/ / 
P.16 

"... contaminated air 1s drawn in through the intake duct into 

whfch sprays of water are introduced. These sprays, upon impinging 

on the high speed blower wheel are reduced to fog which intimately 

mix with the contaminated air, dissolving the contaminants. The 

blower wheel being axially located within the separating chamber also 

acts as the impeller of a centrifuge, thereby separating the water 

entrained contaminants which are drained at the bottom of the unit. 

The cleaned air spirals out the discharge located at the top." 

The design gas flow rate of the scrubber is 85 cubic meters per minute 

(3,000 cubic feet per minute). The design water flow rate ranges from 7.6 

to 11.4 liters per minute (2 to 3 gallons per minute). The scrubber water 

1s not recycled and the scrubber 1s continuously sprayed with fresh 

water. 

The scrubber wastewater 1s combined with other waste streams and 1s 

drained to a wastewater treatment system. Sulfur dioxide 1s used to 

pretreat the wastewater to reduce the hexavalent chromium to trivalent 

chromium. After pretreatment, the wastewater 1s pumped to a clarifler 

where a polymer 1s added causing the heavy metals to precipitate as sludge 

and settle to the bottom of the tank. Clean water 1s then drawn off the 

top. The sludge 1s pumped to a press where it 1s compressed Into a cake. 

V. Observations 

A small amount of gassing occurred at the sides of the tank 

(cathode) and around the workpiece (anode) while the tank was 1n 

operation. However, the gas did not appear to be breaking through the 

plating solution surface. There was no chromic acid visible on a piece of 

clean white paper that was held over the bath for a short period of time. 

VI. Conclusions 

The Reliable Plating Company plant in Bridgeport, Connecticut, 1s 

representative of a small job shop that performs chromic add anodizing of 

aircraft and miscellaneous parts. To determine the desirability of 

performing emissions testing, it 1s recommended that a chromium mass 

balance be performed on the chromic acid anodizing operation by collecting 

samples of the once-through scrubber water to determine if the quantity of 

chromic ad d taken up in the scrubber water indicates whether emissions 

appear to be significant. If the results of the mass balance show that 

chromic ad d emissions from anodizing tanks are negligible, no further 

testing would be performed. However, if the results of the mass balance 

Indicate that chromic acid emissions may be significant, emissions testing 

on the anodizing bath will be recommended. 

VII. Reference 

1. Niehaus Brothers, Inc., Nelhaus Fume Separators, Indianapolis, 

Indiana. 1986. 

/r 
P.17 

Attachment 2 

SOURCE SAMPLING PROCESS DATA SHEETS 

Place: Reliable Plating & Polishing Company 

Bridgeport, Connecticut 

Test run No. 1 

Test start time: 

Test stop time: 

Time, 

24-h 

clock 

09:35 

09:45 

09:50 

09:55 

10:05 

10:15 

10:20 

10:25 

10:35 

10:40 

Operating 

voltage, 

volts 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

09 

10: 

1 

:35 

40 

Tank parameters 

Operating 

current, 

amperes 

100 

80 

80 

80 

80 

80 

80 

80 

80 

80 

Temp., 

*C CF) 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

(95) 

(95) 

(95) 

(95) 

(95) 

(95) 

(95) 

(95) 

(95) 

(95) 

Date: 

Grab 

samples 

taken at 

— 

— 

9:50 

--

10:05 

— 

10:20 

— 

10:35 

April 1 , 1987 

Scrubber parameters 

water f t ow 

rate, 2,/min 

(gal/min) 

7.57 (2.0) 

— 

~ 

~ 

— 

— 

— 

— 

7.34 (1.94) 

--

Grab 

samples 

taken at 

— 

— 

09:50 

— 

09:50 

__ 

10:20 

— 

10:35 

— 

/£> 
P.18 

SOURCE SAMPLING PROCESS DATA SHEETS 

Place: Reliable Plating & Polishing Company 

Bridgeport, Connecticut 

Test run No. 2 

Test start time: 11:00 

Test stop time: 12:05 

Date: April 1, 1987 

Time, 

24-h 

clock 

11 

11 

11 

11 

11 

11 

11 

12 

12. 

05 

.15 

25 

30 

35 

45 

55 

00 

05 

Operating 

voltage, 

volts 

35 

36 

36 

36 

36 

37 

36 

36 

36 

Tank parameters 

Operating 

current, 

amperes 

40 

40 

30 

30 

20 

20 

20 

20 

20 

Temp., 

*C CF) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

Grab 

samples 

taken at 

— 

11:15 

~ 

11:30 

— 

11 :45 

— 

12:00 

— 

Scrubber parameters 

Water f1ow 

rate, i/mIn 

(gal/min) 

7.34 (1.94) 

~ 

— 

~ 

— 

— 

— 

— 

7.00 (1.85) 

Grab 

samples 

taken at 

— 

11:15 

« 

11:30 

— 

11 :45 

~ 

12:00 

— 

n 
P.19 

SOURCE SAMPLING PROCESS DATA SHEETS 

Place: Reliable Plating & Polishing Company 

Bridgeport, Connecticut 

Test run No. 3 Date: April 1, 1987 

Test 

Test 

Time, 

24-h 

clock 

12:15 

12:25 

12:35 

12:40 

12:45 

12:55 

13:05 

13:10 

13:15 

start time: 

stop time: 

Operating 

voltage, 

volts 

37 

37 

37 

37 

37 

37 

37 

37 

37 

12:08 

13:15 

i 

Tank parameters 

Operating 

current, 

amperes 

20 

20 

20 

20 

20 

20 

20 

20 

20 

Temp., 

*C CF) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

Grab 

samples 

taken at 

— 

12:25 

— 

12:40 

~ 

12:55 

— 

13:10 

TM ~ 

Scrubber 

wa+er t1ow 

rate, 8,/min 

(gal/min) 

--

— 

~ 

— 

— 

~ 

~ 

— 

parameters 

7.34 (1.94) 

Grab 

samples 

taken at 

— 

12:25 

« 

12:40 

— 

12:55 

~ 

13:00 

"""" 

/ / 
P.20 

SOURCE SAMPLING PROCESS DATA SHEETS 

Place: Reliable Plating 

Test run No. 4 

Test start time: 13:25 

Test stop time: 14:30 

Date: April 1, 1987 

Time, 

24-h 

clock 

13:30 

13:40 

13:50 

13:55 

14:00 

14:10 

14:20 

14:25 

14:30 

Tank 

Operat ing 

voltage, 

volts 

36 

36 

36 

36 

36 

36 

36 

36 

36 

parameters 

Operating 

current, 

amperes 

100 

100 

100 

100 

100 

100 

100 

100 

100 

Temp., 

*C CF) 

34 (94) 

34 (94) 

34 (94) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

35 (95) 

Scrubber 

Grab 

samples 

taken at 

— 

13:40 

~ 

13:55 

« 

14:10 

— 

14:25 

— 

parameters 

water flow 

rate, i/min 

(gal/min) 

~ 

--

--

— 

— 

— 

— 

~ 

7.42 (1.96) 

Grab 

samples 

taken at 

— 

13:40 

— 

13:55 

~ 

14:10 

~ 

14:25 

— 

/? 
P.21 

Attachment 3 

DERIVATION OF MASS BALANCE 

Assumptions: 

(1) No chromium impinges on the internal surfaces of the ductwork or 

scrubber. 

(2) Capture efficiency of ventilation system is 100 percent. 

(3) No chromium enters through the inlet water stream of the 

scrubber. 

Chromium Mass Balance: 

(1) M = Mg+Mw 

where, M = chromium mass rate in inlet gas stream, kg/h; 

Mg = chromium mass rate in outlet gas stream, kg/h; and 

Mw = chromium mass rate in outlet water stream, kg/h. 

Equation 1 can be rewritten as: 

(2) M = (Qg)(Cg)+(Qw)(Cw) 

where, Qg = flow rate of outlet gas stream, m /h; 

Cg = concentration of chromium in outlet gas stream, kg/m ; 

Qw = flow rate of outlet water stream, a,/h; and 

Cw = concentration of chromium in outlet water stream, kg/a 

Alternatively, 

Mg = M(l-E) 

where, E = scrubber efficiency, percent 

Restructuring, 

M

 - TSTT 

Substituting for Mg, 

(3) M=^2 l 

or 

Mw = (E)(M) 

Restructuring, 

Substituting for Mwo, 

(4) M . IMlCwi 

<ao 
P.22 

EXAMPLE CALCULATION OF CHROMIUM UNCONTROLLED EMISSION RATE 

Given: Qw = 7.34 n/min or 440.4 i/h 

E = 90 percent 

Cw = 3.9 yg/ml or 3.9x10" kg/a 

Uncontrolled chromium emission rate 

M =

 (44( M * /h) feo X l ° ~ 6 kq/<0

 = 0.0019 kg/h 

*t