P.1 

OAR Box 1392 

Prepped by Ollie Stewart 

Document Number: 

132) ll-A-7 

Docket Number: 

A-94-52 

Printed 7/7/2008 9:45:59 AM Sheet 132 of 136 
P.2 

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United Slates 

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ADDENDUM TO ! 

ASSESSMENT OF STYRENE EMISSION 

CONTROLS FOR FRP/C AND 

BOAT BUILDING I 

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Dffice of Air Qualit1 

and Stand 

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P.4 

r 

EPA-600/R-96-136 

November 1996 

Addendum to Assessment of Styrene 

Emission Controls for FRP/C and 

Boat Building Industries 

Final Report 

by: 

Emery J. Kong, Mark A. Bahner, and Sonji L. Turner 

Research Triangle Institute 

RO. Box 12194 

Research Triangle Park, NC 27709 

EPA Contract 68-D1-0118, W.A. 192 

EPA Project Officer: Norman Kaplan 

Air Pollution Prevention and Control Division 

National Risk Management Research Laboratory 

U.S. Environmental Protection Agency 

Research Triangle Park, NC 27711 

Prepared for 

U.S. Environmental Protection Agency 

Office of Research and Development 

Washington, DC 20460 
P.5 

Abstract 

This report is an addendum to a 1996 EPA report entitled Assessment of Styrene Emission 

Controls for FRP/C and Boat Building Industries. This addendum presents additional evaluation 

of the biological treatment of styrene emissions, Dow Chemical Company's SORBATHENE® 

solvent vapor recovery system, Occupational Safety and Health Administration regulations and 

other policies that affect the fiber reinforced plastics/composites (FRP/C) and boat building 

industries, and secondary pollution and natural gas usage resulting from various emission control 

options. 

This study concludes that: 

• Based on available results from bench- and pilot-scale studies and full-size 

operation, biofiltration or a bioscrubber could be a viable control option for 

treatment of styrene emissions. 

• Dow Chemical's SORBATHENE® vapor recovery system was developed for 

high-concentration, low-flow exhaust from storage vents and would not be 

economically feasible for low-concentration, high-volume flow typically found in 

the most prominent processing techniques in the FRP/C and boat building 

industries. 

• Employers should comply with current or future permissible exposure limits 

(PELs) for styrene using feasible engineering controls and should provide 

respiratory protection to employees when worker exposure cannot meet PELs 

after feasible engineering controls have been implemented. It is also an industrial 

practice for employers to provide additional respiratory protection to the 

employees even though the PELs are met. 

• Direct thermal oxidation or catalytic oxidation would be less economical than 

preconcentration/oxidation technologies for low-concentration, high-volume 

emissions typically found in the industries. Secondary pollution and natural gas 

usage could be reduced significantly when using preconcentration technologies 

followed by catalytic oxidation. 
p.e 

Contents 

Abstract ii 

Figures v 

Tables v 

Acronyms and Abbreviations vi 

Conversion Table viii 

Chapter 1 Introduction 1 

References 1 

Chapter 2 Biological Treatment 2 

2.1 System Information Requested 2 

2.2 Descriptions of Biological Treatment Systems 2 

References 8 

Chapter 3 Novel Styrene Emission Control Technology 9 

3.1 Dow Chemical SORBATHENE® Solvent Vapor Recovery Unit 9 

References 11 

Chapter 4 OSHA Regulations and Policies Affecting Worker Exposures in the FRP/C and 

Boat Building Industries 12 

4.1 Summary and Implication of OSHA Regulations 12 

4.2 De Minimis Violations 13 

4.3 Local Air Flow Management and Spray Booth Modifications 14 

References 15 

Chapter 5 Assumptions in the Society of Plastics Industry/Composites Institute's (SPI/CI) 

Study on Noneconomic Impacts of Incineration Controls 17 

5.1 Use of Thermal Oxidizer 17 

5.2 Control Device Inlet Concentration of 20 ppm 17 

5.2.1 Economic Incentives for Maximizing Inlet Concentrations 19 

5.2.2 Exhaust Concentrations at Existing Plants 19 

5.2.3 Recent and Potential Future Changes in Allowable Exposures to Styrene21 

5.2.4 Existing Relationships Between Worker Exposure and Exhaust 

Concentration 21 

5.2.5 Potential Methods to Increase Concentration to Downstream Controls . 21 

5.2.6 Conclusions on Assumption of Control Device Inlet Concentration of 20 

ppm 23 

References 24 

Chapter 6 RTI Analysis of Noneconomic Impacts of Controls 25 

6.1 Normalized Curves for Natural Gas Usage and Secondary Pollutant Emissions 25 

6.1.1 Natural Gas Usage 25 

iii 
P.7 

Contents (continued) 

6.1.2 Carbon Dioxide Emissions 27 

6.1.3 Nitrogen Oxide Emissions 27 

6.2 Calculations for Specific Plant 29 

6.2.1 Natural Gas Usage 31 

6.2.2 Carbon Dioxide Emissions 31 

6.2.3 Nitrogen Oxide Emissions 34 

6.2.4 Radon Emissions 34 

6.3 Conclusions 37 

References 37 

APPENDIXES 

A Comments on Individual Statements in the SPI/CI Study 39 

B Revision of the Styrene Control Cost Spreadsheet Model and Cost Figures 43 

iv 
^ 8 

Figures 

No. Page 

2-1 W K Weege GmbH bioscrubber system 7 

3-1 Process diagram of a SORBATHENE solvent vapor recovery unit 10 

5-1 Cost curves for a large plant (400 tons per year inlet) 18 

5-2 Typical open molding operation in a spray booth 22 

6-1 Normalized natural gas usage for various control options and for sensible heating 

of exhaust stream 26 

6-2 Normalized additional carbon dioxide generated by natural gas combustion for 

various control options 28 

6-3 Normalized NOx emissions for various control options 30 

6-4 Natural gas usage for various control options and for sensible heating at a typical plant 32 

6-5 Carbon dioxide emissions for various control options at a typical plant 33 

6-6 Nox emissions for various control options at a typical plant 35 

6-7 Radon emissions due to natural gas combustion for various control options at a typical 

plant 36 

Tables 

No. Page 

2-1 Properties for Styrene Abatement Biosystems 4 

5-1 Styrene Exhaust Concentrations at Existing Open Molding Plants with Resin/Gel Coat 

Usage Greater than 1,000 ton/yr 20 

5-2 Comparison of average styrene exhaust concentration (290 ppm) with worker exposure 

levels at Lasco Bathware, South Boston, VA 23 

6-1 Characteristics for Specific Plant (Universal Rundle, in Ottumwa, Iowa) 31 
P.9 

Acronyms and Abbreviations 

ACGIH 

BACT 

Btu 

CAAA 

CE 

CEFIC 

CFCs 

CO 

C02 

EC 

EC&C 

EPA 

FID 

FRP/C 

ft 

ft/min 

GPRMC 

HAP 

H.R. 

kW 

kWh 

lb 

lb/h 

LEL 

MACT 

MIAB 

NFPA 

NOx 

OAQPS 

OSHA 

PADRE 

PC 

PEC 

PEL 

ppm 

PSA 

psig 

REECO 

RPC 

RTI 

SIC 

SMC 

American Council of Government Industrial Hygienists 

best available control technology 

British thermal unit 

Clean Air Act Amendments of 1990 

capital equipment (cost) 

Unsaturated Polyesters Sector Group of European Chemical Industry Council 

chlorofluorocarbons 

carbon monoxide 

carbon dioxide 

equipment cost 

Environmental C&C, Inc. 

Environmental Protection Agency 

flame ionization detector 

fiber-reinforced plastics/composites 

feet 

feet per minute 

European Organization of Reinforced Plastics/Composite Materials 

hazardous air pollutants 

heat recovery 

kilowatt 

kilowatt-hour 

pound 

pounds per hour 

lower explosive limit 

maximum achievable control technology 

Molnbacka Industri, AB 

National Fire Protection Association 

nitrogen oxides 

Office of Air Quality Planning and Standards 

Occupational Safety and Health Administration 

Polymer Adsorption and Removal 

personal computer 

purchased equipment cost 

permissible exposure limits 

parts per million (by volume) 

pressure swing adsorption 

pounds per square inch, gage 

Regenerative Environmental Equipment Co., Inc. 

reinforced plastic composites 

Research Triangle Institute 

Standard Industrial Classification 

sheet molding compound 

Vl 
P.10 

SPI/CI 

STC 

STEL 

TCI 

TDC 

TLV 

ton/yr 

TRI 

TVA 

TWA 

VOC 

yr 

°c 

°F 

Society of the Plastics Industry/Composites Institute 

Southeastern Technology Center 

short-term exposure limit 

total capital investment 

total direct cost 

threshold limit value 

tons per year 

Toxics Release Inventory 

Tennessee Valley Authority 

time-weighted average 

volatile organic compound 

year 

degrees Celsius 

degrees Fahrenheit 

Vll 
P.11 

Conversion Table 

The U.S. Environmental Protection Agency policy is to express all measurements in Agency 

documents in metric units. In this report, however, to conform to industrial convention, English 

units are used. Conversion factors from English to metric units are given below. 

English Unit ; Multiply by To Obtain 

joule 

°C 

m 

m

2 

m

3 

mVmin 

l/min 

cm 

mm Hg 

kg 

kilopascal 

Mg 

Btu 

op 

ft 

ft2 

ft3 

ft3/min (cfm) 

gal/min 

inch 

in. H20 

lb 

psia 

ton 

1.055xl03 

(°F-32)/1.8 

0.3048 

0.0929 

0.0283 

0.028314 

3.79 

2.54 

1.87 

0.454 

6.895 

0.907 

Vill 
P.12 

Chapter 1 

Introduction 

The 199Q Clean Air Act Amendments (CAAA) mandate the development and 

promulgation of standards for hazardous air pollutants (HAP) emitted from a multitude of source 

categories by the year 2000. Styrene is listed as a HAP in the CAAA, and it is known to be 

emitted from the fiberglass-reinforced plastics/composites (FRP/C) and boat building industries. 

An earlier study (Kong et al., 1996) assessed the available control technologies, their efficiencies, 

performance, and cost. That study also reviewed and summarized Occupational Safety and 

Health Administration (OSHA) regulations governing the worker exposure issues, and presented 

the air flow management practices that could achieve cost-effective control of styrene emissions. 

This report presents additional evaluation of the biological treatment of styrene 

emissions, Dow Chemical Company's SORBATHENE® solvent vapor recovery system, OSHA 

regulations and other policies that affect the FRP/C and boat building industries, and secondary 

pollution and natural gas usage resulting from various emission control options. 

This study concludes that: 

1. Based on available results from bench- and pilot-scale studies and full-size operation, 

biofiltration or a bioscrubber could be a viable control option for treatment of styrene emissions. 

2. Dow Chemical's SORBATHENE® vapor recovery system was developed for highconcentration, low-flow exhaust from storage vents and would not be economically feasible for 

low concentration, high-volume flow typically found in the most prominent processing 

techniques in the FRP/C and boat building industries. 

3. The employers should comply with current or future PELs for styrene using feasible 

engineering controls and should provide respiratory protection to the employees when worker 

exposure can not meet PELs after feasible engineering controls have been implemented. It is 

also an industrial practice for employers to provide additional respiratory protection to the 

employees even though the PELs are met. 

4. Direct thermal oxidation or catalytic oxidation would be less economical than 

preconcentration/oxidation technologies for low-concentration, high-volume emissions typically 

found in the industries. Secondary pollution and natural gas usage could be reduced significantly 

when using preconcentration technologies followed by catalytic oxidation. 

References 

Kong, E.J., M.A. Bahner, and S.L. Turner. September 1996. Assessment of Styrene Emission 

Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640), 

Research Triangle Park, NC. 
P.13 

Chapter 2 

Biological Treatment 

Biological treatment uses microorganisms in a medium, usually a biofilter or bioscrubber, 

to destroy organic compound emissions in an air stream. Air emissions containing biodegradable 

constituents pass through a biologically active medium. The microorganisms degrade the 

organic constituents in the air stream to essentially carbon dioxide and water. Biofiltration has 

been used for many years in Europe, Japan, and the United States for odor control, but the use of 

biofiltration to degrade more complex air emissions from chemical plants has occurred only 

within the last few years. Descriptions of biofiltration and biotrickling filter systems are 

presented in an EPA report (Kong et al., 1996). Biofiltration and biotrickling filter are similar in . 

principle, but different vendors use different designs and media. This addendum includes 

another new biological treatment system which comprises a bioscrubber and a bioreactor. This 

section presents the process descriptions and information for several biological treatment units 

that have been tested or applied for styrene emissions. 

2.1 System Information Requested 

The Research Triangle Institute (RTI) contacted seven researchers and suppliers to obtain 

available information on their various existing and proposed biological treatment systems. The 

request included but was not limited to information on the following: 

• flow rates - • composition of the bio-medium 

• emission source • incubation period of the bio-medium 

• concentration • size of the biofilter 

• capture efficiency. • pressure drop 

• control efficiency • acclimation period 

• time of operation (hours/day, days/week) • performance during startup 

• number of persons required for operation • performance after periods of shutdown 

• frequency of regeneration • capital and operating costs 

Five facilities responded by the requested deadline to provide information for this report: 

Envirogen, Tennessee Valley Authority (TVA), W K Weege GmbH, Southeastern Technology 

Center (STC), and EnvirOzone, Inc. 

2.2 Descriptions of Biological Treatment Systems 

Envirogen. Envirogen provided information for two units, a pilot-scale biofilter and a proposed 

full-scale biotrickling filter. The pilot-scale biofilter was tested on air discharged from a 

fiberglass spray booth operation. The full-scale biotrickling filter was designed to control styrene 

emissions generated by a sequence batch reactor in a chemical company's wastewater treatment 

facility; however, the system was never put into service. Currently, CVT Bioway is conducting a 

field pilot study with TNO in Europe. This work is confidential and remains unavailable to 
P.14 

Envirogen. (Envirogen and a Dutch company have a joint venture company called CVT 

America. CVT America has potential access to license TNO's technology through a sister 

company called CVT Bioway. CVT Bioway is a separate company from CVT America.) As 

data and information from this field study become available to them, Envirogen will update RTI. 

Information on the Envirogen biotreatment system is presented in an EPA report (Kong et al., 

1996). Properties for their pilot-scale system and design specifications for their full-scale system 

are listed in Table 2-1. 

TVA. In 1989, 1.04 x IO6 kg (1,144 tons) of styrene was emitted by manufacturing industries in 

the Tennessee Valley making styrene the second largest Toxic Release Inventory (TRI) classified 

toxic chemical released in the region (Lackey et al., 1994). Laura Lackey with TVA conducted 

bench-scale and pilot-scale studies to eliminate styrene emissions from the air streams of an 

industrial partner and other varied industrial applications. For bench-scale biofilter experiments, 

a parallel series of three bench-scale 2.8-L biofilters was constructed. All three biofilters were 

packed with a 1:1 (v/v) mixture of pine bark and composted chicken litter. A stainless steel 

screen supported the packing material creating a free space at the bottom of each biofilter. A 

controlled feed of styrene-contaminated gas entered the free space, and purified air exited the top. 

For the bench-scale experiments, biofilters were operated continuously for a 7-month period. 

Biofilter 1, the Control, was autoclaved and served as a sterile control. Biofilter 2 was 

inoculated with a styrene-degrading consortium of organisms, and Biofilter 3 used only naturally 

occurring microorganisms. Inlet styrene concentrations ranged from 50 to 4,000 ppmv and the 

empty bed contact time varied between 1 and 8 minutes. During days 29 to 36, the humidity of 

the incoming air stream was inadvertently dropped below the normal 99 percent to below 50 

percent relative humidity. This drop caused the removal efficiency of Biofilter 2 to decrease to 

60 percent. After the humidity was returned to normal, the performance of Biofilter 2 quickly 

improved and removal efficiency increased to greater than 99 percent. This problem did not 

occur with Biofilter 3. After the initial acclimation period, the performances of Biofilter 2 and 

Biofilter 3 were similar, greater than 99 percent (L.W. Lackey, TVA, personal communication, 

Sept. 4, 1996). 

The pilot-scale biofilter that was installed at a boat building manufacturing site was 0.8 

meters in diameter with a total packing volume of 1.26 m3 (Holt and Lackey, 1995). It was also 

filled with a 1:1 (v/v) mixture of pine bark and composted chicken litter. The pilot-scale biofilter 

was monitored for 3 months. During normal manufacturing, the spray booth was operated for 

three shifts each day (20 h/d). Following the first week of operation and microbial acclimation, 

the manufacturing facility shut down for 1 week. During the shutdown, the biofilter continued to 

operate, and the system was maintained under aerobic conditions by blowing an uncontaminated 

air stream through the biofilter. Some styrene breakthrough was noted during the first shift after 

the week of downtime. However, no styrene was detected in the biofilter effluent for the next 2 

months when the empty bed contact time was maintained at a constant rate. Additional 

information about the properties for both systems is listed in Table 2-1. Lackey plans to design a 

demonstration-scale 340-m3/min (12,000-ft3/min) biofiltration system based on the results of the 

two studies. However, a decision to construct the demonstration-scale system is currently on 

hold until there are regulatory requirements to build it. 
Table 2-1. Properties for Styrene Abatement Biosystems 

Bioreactor 

Parameters 

Unit type 

Reactor type 

Reactor size 

Emissions source 

Other pollutant(s) 

Flow rate 

Styrene concentrations 

Control efficiency 

Time of operation 

Persons needed for 

operation 

Media replacement 

Companies 

ENVIROGEN 

Pilot 

Biofilter 

0.85 m3 

(30 ft') medium 

Fiberglass spray 

booth operation 

Full-scale'* 

Biofilter 

0.28 m'(10 ft') 

Wastewater 

treatment facility 

NA 

7.08 x 10' to 

5.66 x lO'm'/s 

(15 to 120ft'/min) 

NA 

>95% @ 30+ sec 

85% to 95 %@ 15 

sec 

16h/d,5d/wk, 

4 months 

0.6608 m'/s 

(1,400 ft'/min) 

NA 

90% removal 

24 h/day 

1 

5 to 7 years Life of system 

TVA 

Benchb Pilot 

Biofilter 

2.8xl0'm ' 

(0.099 ft') 

Controlled 

contaminated feed 

Acetone 

NA 

50 to 4,000 ppmv 

(inlet) 

>99% removal 

(Biofilter 2) 

>99% removal 

(Biofilter 3) 

7 months 

1.26 m' 

(44.5 ft') 

medium 

Boat 

manufacturer 

MEK 

Acetone 

2.83x10-'to 

2.12 x 10' 

(6 to 45 ft'/min) 

0 to 400 ppmv 

(inlet) 

>98% removal 

13 months 

None 

NA 

W K Weege 

Full-scale 

Bioscrubber 

Designed for 

treatment required' 

Automotive parts 

production 

NAd 

20,000 m'/h 

(11,774 ft'/min) 

50 to 60 ppm 

(inlet) 

5 ppm (outlet) 

- 90% removal 

8 h/d, 5 d/wk, 

10.5 mo/yr 

None 

Life of system 

STC 

Pilot 

Biofilter 

21.62 m' 

(763.4 ft') 

FRP facility 

MEK 

0.472 to 0.944 m'/s 

(1,000 to 2,000 

ft'/min) 

30 ppm (inlet) 

0.3 ppm (outlet) 

99% 

24 h/day 

None 

4 to 7 years 

(continued) 
Table 2-1. Continued 

Bioreactor 

Parameters 

Unit type 

Media composition 

Acclimation period 

Pressure drop 

Startup performance 

Shutdown 

recovery 

Capital cost 

Operating cost 

Companies 

ENVIROGEN 

Pilot 

Proprietary 

engineered organic 

based material 

- 1 week 

1 in. to 2 in. H20 

@ start-up 

8 in. H20 design 

75 % @ 60 sec 

5to8 h 

(weekend 

shutdown) 

NA 

NA 

Full-scale3 

Synthetic packing 

1 to 2 weeks 

(expected) 

< 1 in. H20 

(expected) 

NA 

NA 

Available upon 

request 

Available upon 

request 

TVA 

Bench" Pilot 

1:1 (v/v) pine bark and composted 

chicken litter 

- 5 days (Biofilter 2) 

- 55 days (Biofilter 

3) 

0.003 in. H20 (max) 

NA • 

0.75 in. H20 

(max) 

NA 

NA 

NA 

NA 

VVKWeege 

Full-scale 

Proprietary 

NA 

NA 

NA 

Vi to 1 h 

(after shut-down) 

$450,000 to 

$700,000 

$25/day to 

$30/day 

STC 

Pilot 

80% chicken 

compost 

20% GAC. 

2 to 3 weeks 

20 to 30 in. H2 0 

30 to 70 % 

variable 

$140,000 

(w/engineering) 

$400/month 

NA = not available. 

a. Design parameters of this systems are listed. The system currently is not in use. 

b. A parallel series of three bench-scale biofilters were used for this bench-scale test. Biofilter I was autoclaved and served as a sterile control. Biofilter 2 was 

inoculated with a styrene-degrading consortium of organisms. Biofilter 3 utilized only naturally occurring microorganisms. 

c. Each system is designed to handle specific waste streams. Normal height of filter material is a maximum of 1 to 1.25 m. For 100 to 150 m' of emissions, 

estimate approximately 1 m'of filter material. 

d. System can be engineered for specific waste streams of volatile organic compound (VOCs). A series of bioscrubbers can be designed for each individual unit 

to treat a specific VOC. 
P.17 

W K Weege GmbH. W K Weege GmbH, an engineering company in Wiesbaden, Germany, 

developed a bioscrubber system that removes styrene and other volatile organic compounds 

(VOCs) from industrial waste gases. The bioscrubber system employs a four-step process to treat 

styrene and VOC emissions from industrial waste gas. As shown in Figure 2-1, industrial waste 

gases enter a packed absorption tower where styrene is absorbed into the countercurrent flow of 

the absorbent solution (i.e., water and clean effluent from the bioreactor). The absorption tower 

consists of packing, a droplet separator, and a liquid distributor. After this step, clean air leaves 

the tower, and the styrene-laden absorbent solution is pumped into a stirred bioreactor. In the 

bioreactor, styrene is biologically degraded. After the degradation is complete, proprietary 

additives are applied to maintain the bacteria population, and the clean effluent from the 

bioreactor is pumped to the absorption tower for reuse. No sludge or solid waste is generated 

from the bioscrubber process. 

The bioscrubber system is equipped with sensors and measuring devices and a computer 

to control the operations of the system. W K Weege sells a service contract to maintain and 

operate the system. The personal computer (PC) station is the heart of data acquisition for the 

bioscrubber system. The PC station collects all data and controls various functions of the system, 

such as refilling water to make up for evaporation loss, replenishing the additives, and 

controlling the system. Through modem communication methods, these data are communicated 

back to W K Weege. This information transfer allows W K Weege to continually monitor the 

function of the system and to remotely adjust the system when necessary using a fax modem. 

Two bioscrubber systems exist in Germany: one is a laboratory-scale facility, the other is 

a commercial unit used by a German company using sheet molding compound (SMC) to 

manufacture automotive parts. The commercial unit operated for one year but is no longer in 

operation now. Rudi Weege, company president, provided RTI with an overview of the 

commercial unit. Information for the commercial system is provided in Table 2-1. 

The cost data in Table 2-1 for the W K Weege system are taken from published literature 

(Modern Plastics, 1996). The capital costs for a system handling 11,766 ft3/min are estimated to 

be between $450,000 and $700,000. This can be compared to estimated equipment costs and 

total capital investments of $301,000 and $619,000, respectively, from the biofiltration cost 

spreadsheet developed in the original styrene controls assessment. Operating costs are given as 

approximately $25 to $30 per day. This can be compared with an electrical cost estimate of 

approximately $15 per day from the biofiltration cost spreadsheet (assuming electricity cost of 

$0.06 per kWhr, operating 8 hours per day). 

W K Weege is in the process of establishing a North American subsidiary to introduce 

and commercialize their technology to the FRP composite industry and other industries emitting 

VOCs in North America. According to Weege, the system can be designed to treat various 

VOCs, with each unit dedicated to treating a specific pollutant. 

Southeastern Technology Center (STC). STC is a non-profit corporation whose mission is to 

facilitate the transfer of commercially viable technologies from the government sector to the 

business sector for the purpose of promoting economic development and creating jobs. 

6 
P.18 

Clean Air 

Water • 

Stirrer 

Aerator 

Reactive 

Additive 

Data Acquisition 

! 

Bioreactor 

Absorption 

Tower 

4 Waste 

Gas 

Figure 2-1. WK Weege GmbH bioscrubber system. 
P.19 

Regina Porter at STC is conducting a pilot study for styrene removal from an FRP facility. Her 

research is being conducted under a Department of Energy (DOE) contract. Delphinus 

Engineering, Inc. and EnvirOzone, Inc., both in South Carolina, are subcontractors to STC and 

are responsible for the design and operation of the pilot-scale unit. Delphinus and EnvirOzone 

provided preliminary information for this report for a 21.62-m3 (764-ft3) pilot-scale unit that has 

been designed to treat gaseous exhausts from an FRP facility. The flow rates of the exhaust 

streams range from 0.472 to 0.944 m3/s (1,000 to 2,000 ftVmin). The biofilter media contains 10 

tons (9,070 kg) of chicken compost (80 percent chicken manure and 20 percent granular 

activated carbon) that requires a 2- to 3-week incubation period. Additional information for this 

pilot unit can be found in Table 2-1 (A. Saha, Delphinus Engineering, personal communication, 

Sept. 11, 1996). 

References 

German Firm Develops Styrene-Abatement System. Modern Plastics, p. 17, March 1996. 

Holt, T., and L. Lackey. 1995. Control of gas contaminants in air streams through biofiltration. 

Proceedings of 50th Purdue Industrial Waste Conference. 

Kong, E.J., M.A. Bahner, and S.L. Turner. September 1996. Assessment of Styrene Emission 

Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640), 

Research Triangle Park, NC. 

Lackey, L. W., M.T. Holt, J.R. Gamble, and CE. Breed. 1994. Biofdter Systems for the Control 

of Gas Contamination in Air Streams. Paper presented at the Southern States Annual 

Environmental Conference, October 20. 

J 
Chapter 3 

Novel Styrene Emission Control Technology 

3.1 Dow Chemical SORBATHENE® Solvent Vapor Recovery Unit 

The Dow Chemical Company developed the SORBATHENE® pressure swing adsorption 

(PSA) process in the late 1980s to recover VOCs and other valuable chemical products from 

storage, loading, and process vents. Since 1988, the Dow Chemical Company has installed 19 

SORBATHENE® units to recover hydrocarbon, chlorofluorocarbons (CFCs), chlorinated 

solvents, aromatics, and monomers. Dow Chemical has two SORBATHENE® units for recovery 

of styrene vapors from storage vents. A SORBATHENE® unit can be designed to achieve 99.9% 

VOC removal from vent streams ranging in flow rate from 20 to 3,000 ftVmin with feed 

concentrations between 1,000 and 500,000 ppm (Collick et al., 1996). The chemical components 

are recovered as a condensed liquid. Based on the evaluation of this technology and a follow-up 

conversation with Larry Larrinaga (Radian International, personal communication, September 9, 

1996), the SORBATHENE® technology would be expensive to treat the low-styrene 

concentration (less than 200 ppm) at high flow rates (greater than 5,000 ftVmin) typically found 

in the most prominent processing technologies (e.g., sprayup and hand layup in open molding 

processes) in the FRP/C facilities. 

Process Description. The SORBATHENE® process is typically applied to recover 

organic vapors from process vents, storage tanks, and loading/unloading operations. The process 

uses PSA and the heat generated during adsorption to desorb the VOCs collected on the 

adsorbent. Adsorption is carried out at atmospheric pressure and the heat of adsorption is 

retained in the adsorption bed, then the adsorbate is desorbed at a lower pressure (i.e., under 

vacuum) using the retained heat. Optimal desorption pressures are selected between 50 and 300 

mm Hg (1 and 5.8 psig). As shown in Figure 3-1, the adsorption and desorption steps are batch 

processes that occur simultaneously in alternating twin beds to maintain steady state operation of 

the unit. During the desorption step, a fraction of the clean gas leaving the adsorbing bed is used 

as the backpurge gas for desorption. The concentrated stream of desorbed VOC is drawn through 

a vacuum system then passes through a condenser where the VOC condenses and is removed as a 

liquid. The cooling medium is selected based on the temperature required to condense the vapor. 

Control valves switch the beds over short cycle times to avoid an excessive temperature rise 

caused by the heat of adsorption. The SORBATHENE® unit is designed for the maximum 

instantaneous feed concentration and flow rate that would be expected during operation of the 

unit. The unit would not require adjustment as the inlet flow rate and concentration vary due to 

tank filling operation. 

Standard Operating Conditions. The process has been applied for vent streams ranging 

from 20 to 3,000 ftVmin concentrations between 1,000 and 500,000 ppm. The adsorbent, 

operating pressures and temperatures, and cycle time of the unit are determined in a pilot study 

based on the characteristics of the VOC to be recovered. Each unit is tailored to the specific 

VOC and the characteristics of the exhaust stream. 
P.21 

Adsorbing Unit 

> Clean Vent Stream 

Desorbing Unit 

v J 

S3—"—55 

a 

Feed Stream T-T> - C 

^ : open valve 

p ^ : closed valve 

: adsorbing flow 

: desorbing flow 

Vacuum Pump 

Condenser 

Separator 

Recovered 

Liquid 

Figure 3-1. Process diagram of a SORBATHENE solvent vapor recovery unit. 

10 
P.22 

Control Efficiency. A SORBATHENE® unit has been tested for styrene vapor recovery 

from storage vents and its recovery efficiency was 99.78 percent for an inlet concentration of 

5,742 ppm and an outlet concentration of 13.3 ppm (Hall, 1993). The flow rate was not reported 

for this tested unit; however, exhaust flow rates from storage vents are probably in the severalhundred-ftVmin range when being filled. Polymerization was not encountered for the adsorbent 

used in these applications. 

Applicability to FRP/C/C Processes. The SORBATHENE® technology would not be 

economically feasible for the typical low-concentration and high-flow rate exhaust encountered 

in the FRP/C facilities. A SORBATHENE® unit might be used after the exhaust stream has been 

concentrated and its flow rate reduced by a preconcentration unit; however, its feasibility will be 

determined by the economic value, quantity, and reusability of the recovered styrene. 

Cost. Larry Larrinaga (Radian International, personal communication, September 9, 

1996) estimated that the equipment costs for a SORBATHENE unit treating an optimal flow rate 

of 300 to 500 ftVmin would range from $600,000 to $800,000. The SORBATHENE® unit is 

very sensitive to flow rate and the equipment cost increases dramatically as the flow rate 

increases. Operating costs include electricity cost to operate the adsorbers, vacuum pump, 

condenser, and separator. 

References 

Collick S.J., D.J. Pezolt, and L. Larrinaga. 1996. Capture and Recovery of Tetrafluoromethane 

and Hexafluoroethane from Industrial Vents. Presented at the Air & Waste Management 

Association 89th Annual Meeting, Nashville, TN, June 23-28. 

Hall, T.L. 1993. Dow Chemical SORBATHENE® Solvent Vapor Recovery Unit. Presented at 

American Chemical Society, Emerging Technologies in Hazardous Waste Management, Atlanta, 

GA, September 29, 1993. 

ll 
P.23 

Chapter 4 

OSHA Regulations and Policies Affecting Worker Exposures in FRP/C and 

Boat Building Industries 

OSHA regulations governing the permissible exposure limit (PEL) for styrene and the 

ventilation system design in the FRP industry were summarized and presented in an RTI report 

(Kong et al., 1996). That report also concluded that concentrating the exhaust air stream and 

reducing the exhaust flow would reduce the cost of control. However, the worker exposure is 

bounded by OSHA's PEL for styrene. The current 8-hour time-weighed-average (TWA) PEL for 

styrene is 100 ppm. The TWA short-term exposure limit (STEL) is 200 ppm for 15 minutes 

during a work day and 600 ppm for 5 minutes in any 3 hours. 

John B. Jenks, the Chairman of the Society of the Plastics Industry, Inc.'s Styrene 

Information & Research Center, and several industry officials sent a letter to Joseph A. Dear, the 

Assistant Secretary of Labor for OSHA, on January 29, 1996, and declared a willingness to 

voluntarily comply with lower exposure limits than those set by OSHA in its January 1989 rule 

on PEL for styrene and other air contaminants (OSHA, 1996). The lower limits are 50 ppm for 

an 8-hour TWA and 100 ppm for short-term exposure. The industry groups volunteering to 

lower exposure limits are the Society of the Plastics Industry, Inc.'s Composites Institute, 

Composites Fabricators Association, National Marine Manufacturers Association, and 

International Cast Polymer Association. These industry groups use polyester resins that emit 

styrene in the production processes. The goal is for these industry groups to comply with the 

lower exposure limits by July 1997. 

As the worker exposure limits are lowered, more efficient exhaust systems will be needed 

to remove the same amount of emissions or employees who may not presently be wearing 

respirators will need to wear them. General ventilation, also called dilution ventilation because it 

uses fresh air to achieve lower worker exposure levels, is not practical and would be expensive in 

the winter when makeup air is heated to maintain a constant temperature for product quality. 

Therefore, new air flow management practices to remove styrene emissions effectively or a 

respiratory protection program will be necessary to comply with lower exposure limits. 

This section presents (1) the summary and implication of OSHA regulations related to 

styrene emissions and ventilation in the FRP industry, (2) the explanation for "de minimis 

violations" under the OSHA policy, and (3) local air flow management practices and 

modifications to spray booths that could be considered for the ventilation and worker exposure 

issues. 

4.1 Summary and Implication of OSHA Regulations 

If a facility does not have a designated booth or area for gel coating and resin application 

in an open molding process, the emissions from these operations will be dispersed in the work 

12 
area and the surrounding open space. Under these conditions, the worker exposures are limited 

to the styrene PELs listed in Table Z-2 in 29 CFR § 1910.1000 (OSHA, 1993) or as shown 

above. Title 29 CFR § 1910.1000 (e) states that administrative or engineering controls (e.g., 

enclosure or confinement of the operation, general and local ventilation, and substitution of less 

toxic materials) must first be determined and implemented whenever feasible. When such 

engineering controls are not feasible to achieve full compliance or while they are being instituted, 

protective equipment or any other protective measures should be used to keep the exposure of 

employees to air contaminants within the limits prescribed in the section. Whenever respirators 

are used, their use should comply with requirements in 29 CFR § 1910.134 "Respiratory 

Protection." 

When a facility uses a spray booth, its design must comply with regulations in 29 CFR § 

1910.94(c) and § 1910.107. Section § 1910.94 (c) lists the design and construction of the spray 

booth and the minimum air flow velocities that must be designed and maintained at the entrance 

to the spray booth under various operating conditions in order to meet health and safety 

requirements. Section § 1910.107 is adopted by OSHA from National Fire Protection 

Association (NFPA) 33-1969 (NFPA, 1969) "Standard for Spray Finishing Using Flammable and 

Combustible Materials." The NFPA-33 standard is explicitly a fire and explosion safety 

standard. Therefore, the OSHA standard at 29 CFR § 1910.107 pertains to the prevention of 

workplace fire and explosion hazards and does not pertain to health considerations. 

Because the industry has volunteered to comply with lower PELs, facilities having 

difficulty meeting the lower limits will have to build spray booths for their styrene-emitting 

operation, apply air flow management to exhaust styrene emissions, or provide respirators for 

employees who could be exposed to styrene concentrations above the PELs. These facilities will 

choose one of these options based on the feasibility of using engineering controls, building spray 

booths, applying air flow management practices, changing material/equipment/process, or 

providing personal respirators. When the employee exposures are above the PELs, as determined 

by personal sampling, the employer can work with the OSHA compliance officer to determine a 

schedule for an interim abatement system (e.g., providing respirators to employees) and a long 

term abatement system (e.g., building a ventilation system). Feasibility of the abatement systems 

will be considered by the facility operator and the compliance officer in meeting the PELs. If 

worker exposures still can not meet PELs after engineering controls have been employed, then 

the respiratory program will become a permanent program (Smith, OSHA, personal 

communication, October 15, 1996). 

4.2 De Minimis Violations 

According to the OSHA policy (Shepich, 1990), de minimis violations are violations of 

standards that have no direct or immediate relationship to employee safety or health. Whenever 

de minimis conditions are found during an inspection, they are documented the same way as any 

other violation but are not included on the citation. De minimis violations result in no penalty 

and no required abatement. The criteria for finding a de minimis violation are as follows: 

13 
P.26 

An employer complies with the clear intent of the standard but deviates from its particular 

requirements in a manner that has no direct or immediate relationship to employee safety and 

health. These deviations may involve distance specifications, construction materials 

requirements, use of incorrect color, minor variations from recordkeeping, testing, or 

inspection regulations, or the like. 

An employer complies with a proposed standard or amendment or a consensus standard 

rather than with the standard in effect at the time of the inspection when the employer's 

action provides equal or greater employee protection. 

An employer's workplace is at the "state of the art" that is technically beyond the requirement 

of the applicable standard and provides equivalent or more effective employee safety or 

health protection. 

Under an OSHA policy for de minimis violations, employers are encouraged to abide by 

the standard applicable to their operations that provides equal or greater employee protection 

rather than with the OSHA standard in effect at the time of the inspection. 

4.3 Local Air Flow Management and Spray Booth Modifications 

The most effective way to reduce worker exposure is to directly remove styrene emissions 

from the source before the pollutants have a chance to disperse. Local air flow management, 

such as local extraction ventilation or a spray booth, removes emissions at the source and 

therefore reduces the amount of air to be exhausted and the amount of makeup air to be heated. 

Several local extraction ventilation systems are presented in the earlier report (Kong et al., 1996). 

These local extraction ventilation systems apply the push-pull ventilation principle in that fresh 

makeup air is admitted at one end of the work area and the air current picking up the emissions is 

exhausted at the other end of the work area. An operator can reduce unnecessary exposure by 

staying in the upwind side of the ventilated work area. 

As the EPA Office of Air Quality Planning and Standards (OAQPS) develops maximum 

achievable control technology (MACT) standards for the FRP industry, new facilities using 

greater than a certain quantity of resin and gel coat in an open molding process may be required 

to reduce their emissions. Emissions from concentrated sources in certain operations, such as 

continuous lamination, pultrusion, and SMC production, can be captured and exhausted using a 

vent hood. Emissions from other open molding processes, such as gel coating and resin sprayup, 

need to be confined in a spray booth that meet OSHA's requirements. A spray booth can be 

designed to meet the requirements of a total enclosure so that the emissions can be completely 

captured. In this case, fresh makeup air should be supplied to the operator's breathing zone in 

the spray booth. 

If the worker exposures are still higher than the PELs after proper engineering controls 

(i.e., confinement, local extraction, or general ventilation) have been implemented, then the 

operator should wear a respirator or a positive-pressure respirator with fresh uncontaminated air 

supply. The fresh air supplied to a positive-pressure respirator should meet certain air quality 

14 
requirements and if the air is supplied by an oil-based compressor there must be a CO alarm to 

detect CO in the air (Smith, OSHA, personal communication, October 15, 1996). 

It is common for the employers of some large FRP and boat building facilities to provide 

respirators to their employees for additional protection even though they may in compliance with 

the PELs. Positive-pressure respirator with full body protection and fresh air supply is not 

common in the FRP and boat building industries; however, such a system is used in an enclosed 

paint booth in Hatteras Yachts in New Bern, North Carolina. 

Modifications to spray booths, such as a split flow recirculation, have been examined in a 

large painting booth at a military installation (Hughes et al., 1994). A portion of the exhaust 

from the spray booth that contain less pollutants is recirculated to the front of the spray booth 

after mixing with fresh makeup air. The concentration in the return air is less than the PELs. 

The balance of the exhaust, which is at a higher concentration, is vented to an add-on emission 

control device. The purpose of recirculation is to increase the outlet concentration and reduce the 

exhaust flow so that the capital and operating costs of the add-on control can be minimized. The 

recirculating air can be returned to the spray booth at any point, either mixed with fresh makeup 

air or not mixed with fresh makeup air. In the latter case, the fresh makeup air can be supplied to 

the breathing zone of the operator to provide the most protection. Although recirculation in the 

spray booth is not recommended by OSHA, the bottom line is that worker exposures should not 

exceed the PELs (R. Fairfax, Health Compliance Program, Occupational Safety and Health 

Administration, personal communication, September 9, 1996). 

If all forms of air flow management are not feasible, a facility should consider 

preconcentrating the exhaust stream to reduce the flow rate and to increase the concentration of 

the exhaust stream for an add-on control. Preconcentration reduces not only the capital cost but 

also the operating cost of the add-on control; it also reduces natural gas usage and generates 

fewer secondary pollutants than straight thermal oxidation of the entire exhaust stream. An 

analysis of secondary pollution and natural gas usage for various control options is presented in 

Chapter 5. 

References 

Hughes, S., J. Ayer, and R. Sutay. 1994. Demonstration of Split-Flow Ventilation and 

Recirculation as Flow-Reduction Methods in an Air Force Paint Spray Booth, AL/EQ-TR-1993-

0002, Armstrong Laboratory, Environics Directorate, Tyndall AFB, FL. 

Kong, E.J., M.A. Bahner, and S.L. Turner. September 1996. Assessment of Styrene Emission 

Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640), 

Research Triangle Park, NC. 

National Fire Protection Association (NFPA). 1969. Standard for Spray Finishing Using 

Flammable and Combustible Materials, NFPA 33. Quincy, MA. 

15 
P.27 

OSHA (Occupational Safety and Health Administration). 1993. Occupational Safety and Health 

Standards. 29 CFR 1910. Code of Federal Regulations. Washington, DC: Office of the Federal 

Register, July 1. 

OSHA (Occupational Safety and Health Administration). 1996. OSHA Announces that Styrene 

Industry has Adopted Voluntary Compliance Program to Improve Worker Protection. News 

Release USDL:96-77, March 1. 

Shepich, T.J. 1990. Directorate of Compliance Programs, Occupational Safety and Health 

Administration. Letter to S.R. Wyatt, Emission Standards Division, U.S. Environmental 

Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC, 

January 16. 

16 
Chapter 5 

Assumptions in the Society of Plastics Industry/Composites Institute's 

(SPI/CI) Study on Noneconomic Impacts of Incineration Controls 

Energy use and generation of secondary pollution for control devices are dependent on 

the type of control device selected and the flow rate into the control device. The SPI/CI Study on 

Non-Economic Impacts of Incineration Controls (Haberlein, 1996) was based on thermal 

oxidation of a 30,000 ftVmin exhaust stream containing 20 ppm of styrene. The following 

sections discuss the assumptions of a thermal oxidizer operating on a stream containing 20 ppm 

of styrene. Appendix A contains a discussion of other assumptions in the SPI/CI study. 

5.1 Use of Thermal Oxidizer 

The SPI/CI study assumes a thermal oxidizer operating on a stream containing 20 ppm of 

styrene. However, previous RTI analyses of the costs of controls has indicated that preconcentration/oxidation systems have lower annualized costs than straight thermal oxidation for 

control device inlet concentrations below approximately 300 ppm. For example, Figure 5-1 

shows RTI-calculated control costs for thermal oxidation, catalytic oxidation, and three preconcentration/oxidation systems, for a plant with uncontrolled emissions of 400 ton/yr (operating 

4,000 h/yr).1 Figure 5-1 shows that the three preconcentration/oxidation technologies (MIAB, 

Polyad, and Durr rotary concentrator systems) have lower total costs per unit of styrene removed 

than straight thermal oxidation or catalytic oxidation. Therefore, it is likely that an FRP 

company would choose a preconcentration/oxidation system over straight thermal oxidation for 

an exhaust stream containing 20 ppm styrene based on lower total annualized cost. It is also 

likely that an FRP company would attempt to increase the styrene concentration (i.e., lower the 

flow rate), compared to the 20-ppm assumption in the SPI/CI study. This point is discussed in 

the following section. 

5.2 Control Device Inlet Concentration of 20 ppm 

Noneconomic impact analyses in the SPI/CI study are based on an assumed styrene 

concentration of 20 ppm to a thermal oxidizer. To evaluate this assumption, RTI reviewed the 

following: (1) economic incentives for maximizing inlet concentrations (minimizing flow rates) 

to end-of-pipe controls, (2) plant-wide average exhaust concentrations currently found at FRP 

plants, (3) recent and possible future changes to allowable exposure levels for employees of FRP 

plants, (4) existing relationships between employee exposures to styrene and exhaust 

concentrations at FRP plants, and (5) possible methods for new plants to increase concentrations 

(decrease flow rates) to controls while maintaining or lowering employee exposures. 

1

 Figure 5-1 is based on a cost curve presented in a previous EPA report (Kong et al., 1996), with 

corrections as discussed in Appendix B to this report. 

17 
c 

o *; <A 

TJ 

0) 

> f> rem 

0) 

c 0) 

1 _ 

>. 

o 

c 

y 

k . 

a 

a. 

• ^ 

(0 

o O 

_^m^ 

5 

' • 

T— 

ll 

c 

o *; iA 

Y— 

R nnn J 

-\ nnn . 

o,uuu 

A nnr\ -

o nnn -

0 C\C\C\ -, 

<:rUUu i 

1 nnn - i ,\j\j\j 

0 -

246,000 

123,000 

% 

AA 

\V 

1 \ 

^ 

Flow rate,cfm (1 cfm = 0.0283 m3/ 

61,500 41,000 30,750 

^Ss 

^ > 

min) 

24,600 20,500 1 

IIIIII I 

MIAB 

- - - Poly ad (w/oxidation) 

lytic oxidizer (95% H.R. below 100 ppm) 

Thermal oxidizer (95% H.R.) 

— —Durr rotary concentrator 

•••^^^fi 

^ g"*^ . 

7,6 

100 200 300 400 

Concentration (ppm) 

500 600 700 

Figure 5-1. Cost curves for a large plant (400 tons per year inlet). 
P.30 

5.2.1 Economic Incentives for Maximizing Inlet Concentrations 

Previous RTI research demonstrated the economic desirability for a plant considering 

installation of end-of-pipe controls to evaluate methods to minimize flow rate prior to choosing 

any form of end-of-pipe controls. This is demonstrated by Figure 5-1, where the total annualized 

cost per unit of styrene removed decreases for all control choices as flow rate is reduced (i.e., as 

concentration increases). This trend is true even for preconcentration/oxidation systems (i.e., 

even for preconcentration/oxidation systems, the total annualized cost is reduced when design 

flow rate is reduced). Therefore, companies that contemplate end-of-pipe controls would find 

significant economic benefits in increasing control device inlet concentration above 20 ppm, with 

the associated reduction in total flow to the control device. 

5.2.2 Exhaust Concentrations at Existing Plants 

The SPI/CI study was based on a hypothetical exhaust stream averaging 20 ppm. One 

way to evaluate the appropriateness of this concentration is to look at average facility-wide 

exhaust concentrations at existing facilities. Research Triangle Institute and Pacific 

Environmental Services conducted an evaluation of facility-wide styrene exhaust concentrations 

currently found at fiber-reinforced plastics facilities with open-mold spraying operations. The 

results of this evaluation are presented in Table 5-1. Table 5T1 contains only facilities with 

annual (neat, or unfilled) resin-plus-gel-coat usage of greater than approximately 1,000 tons per 

year. 

Average facility-wide exhaust concentrations in Table 5-1 are calculated based on 

facility-wide emissions (in mass per year), total facility exhaust flow rate, and facility operating 

schedule (hours per year). Where possible, values in Table 5-1 for emissions and flow rates are 

based on testing data. Otherwise, resin/gel coat usage and emission factors are used to calculate 

emissions for subsequent exhaust concentration calculations. 

Table 5-1 shows that all eight facilities evaluated currently have average exhaust 

concentrations above 20 ppm. The mean value for the eight facilities is 120 ppm, and the median 

value is 82 ppm. 

Two of the eight facilities listed in Table 5-1 have controls. The A.R.E. facility in 

Massillon, Ohio, which has a thermal oxidizer, has a calculated average styrene concentration of 

231 ppm in the flow stream to the control device. The American Standard facility in Salem, 

Ohio, which has a Polyad preconcentration/catalytic oxidation system, has an average styrene 

concentration of 75 ppm flow stream to preconcentrator. 

In summary, existing facilities with open-mold spraying and combined resin/gel coat 

usage above 1,000 ton/yr typically have average exhaust concentrations that are above the 20 

ppm assumed in the SPI/CI study. 

19 
Table 5-1. Styrene Exhaust Concentrations at Existing Open Molding Plants with Resin/Gel Coat Usage Greater than 1,000 tons/yr 

PLANT NAME 

AQUA GLASS 

A.R.E., INC. 

LASCO BATHWARE 

UNIVERSAL RUNDLE 

AMERICAN STANDARD 

A.R.E., INC. 

MILLENIUM PRODUCTS 

AQUA GLASS 

Arithmetic mean 

Median 

CITY 

KLAMATH FALLS 

MASILLON 

MOAPA 

OTTUMWA 

SALEM 

MOUNT EATON 

ELKHART 

ADAMSVILLE 

ST 

OR 

OH 

NV 

IA 

OH 

OH 

IN 

TN 

UNCONTROLLED 

EMISSIONS (ton/yr) 

1,175 

770 

739 

328 

53 

108 

123 

1,151 

OPERATING 

HOURS (h/yr) 

6,000 

7,488 

4,290 

4,160 

2,500 

3,120 

2,000 

6,000 

PLANT-WIDE 

FLOW RATE 

(ft3/min) 

97,000 

55,000 

155,400 

110,700 

35,000 

70,000 

125,000 

390,000 

AVERAGE 

STYRENE 

CONCENTRATION 

(ppm) 

249 

231 

137 

88 

75 

61 

61 

61 

120 

82 

ro 

o 

XI 
P-32 , 

5.2.3 Recent and Potential Future Changes in Allowable Exposures to Styrene 

Currently, OSHA PELs for styrene are 100 ppm as an 8-hour time-weighted-average 

(TWA) and 200 ppm as a 15-minute short-term-exposure-limit (STEL). The SPI/CI study notes 

that the reinforced plastics industry has voluntarily agreed to meet a 50-ppm TWA and a 100-

ppm STEL. Compliance with the agreement will go into effect in July 1997. The SPI/CI study 

further notes that the American Council of Government Industrial Hygienists (ACGIH) has 

placed styrene on the Notice of Intended Change list to lower the styrene threshold limit value 

(TLV) to 20 ppm, with a STEL of 40 ppm. 

The SPI/CI study uses a control device inlet concentration of 20 ppm. This is equal to the 

TLV being proposed by the ACGIH. RTI has no information to indicate that OSHA currently 

plans to lower the TWA to 20 ppm. 

5.2.4 Existing Relationships Between Worker Exposure and Exhaust Concentration 

Even if the OSHA TWA were lowered to 20 ppm, it would be reasonable to assume that a 

company building a new facility would have an average exhaust concentration to an end-ofrpipe 

control that would be above 20 ppm. One reason for this is the strong economic incentive to 

maximize concentration (minimize flow rate), as discussed in Section 6.1. Another reason for 

this is that most capture systems would logically be oriented to draw styrene away from the 

worker, rather than drawing styrene into the worker's breathing zone. This concept is illustrated 

in Figure 5-2. 

Currently, there is little available data relating average exhaust concentrations to worker 

exposures. Some data are available from the Lasco-South Boston (Virginia) tub-and-shower 

facility, and are presented in Table 5-2. Table 5-2 indicates that gel coat gun operators and 

lamination rollers had the highest average worker exposures during the measurement period and 

that the average ratio of exhaust-duct-concentration-to-worker-exposure was 2.36 and 2.42, 

respectively. 

RTI is analyzing data collected at a tub-and-shower facility in which employee exposure 

and exhaust duct concentration were measured simultaneously. The results of this testing are 

expected to be published by February 1997 (see Section 5.2.5). 

5.2.5 Potential Methods to Increase Concentration to Downstream Controls 

Previous research by RTI identified several potential methods to decrease required flow 

rates for end-of-pipe controls while preventing excess employee exposure levels. These methods 

included: (1) local air flow management, (2) spray booth modifications (such as split-flow spray 

booths and spray booth recirculation), and (3) enclosures and total enclosures. 

RTI is currently analyzing data from proof-of-concept testing at a tub-and-shower facility. 

This testing is evaluating the ability of spray enclosures and air flow management techniques to 

increase exhaust duct concentration while 

21 
NJ 

(O 

Main Filter Bank 

Main Exhaust to Atmosphere 

(high volume, low concentration). 

Fresh Air Supply 

Figure 5-2. Typical open molding operation in a spray booth. 
Table 5-2. Comparison of Average Styrene Exhaust Concentration (290 ppm) (Strum, 

1995) With Worker Exposure Levels (Boyd, 1995) at Lasco Bathware, South Boston, VA 

Job Category 

1. Gel Coat Gun Operator 

2. Lamination Gun Operator 

3. Lamination Roller 

4. Barrier Coat 

Gun Operator 

5. Part Puller 

6. QC Technician 

7. Mixer 

8. Trimmer 

9. Waxer 

Number of 

Measurements* 

5 

17 

6 

5 

2 

4 

5 

1 

1 

Exposure 

Range* 

(ppm) 

88-199 

37-267 

92-142 

61-105 

32-39 

23-75 

15-44 

Average 

Exposure* 

(ppm) 

123.0 

90.4 

120.0 

79.4 

35.3 

37.0 

31.6 

46.0 

25.0 

Average Ratio, 

Exhaust/Exposure 

2.36 

3.21 

2.42 

3.65 

8.22 

7.84 

9.18 

6.30 

11.60 

Data provided to Madeleine Strum by Daniel Boyd (Boyd, 1995). 

maintaining or lowering worker exposures. The enclosure concept involves placing a part inside 

an enclosure while the spray gun operator stands outside the enclosure. The air flow 

management techniques involve the use of a close-capture exhaust panel. In this testing, one 

flame ionization detector (FID) device continuously measured exhaust duct concentration while 

another (portable) FID was used to continuously monitor worker exposure. In this manner, the 

ratio of exhaust duct concentration to worker exposure concentration could be continuously 

monitored and compared with "baseline" results from an unmodified spray booth. The results of 

the RTI enclosures/air flow management testing are expected to be available by February 1997. 

5.2.6 Conclusions on Assumption of Control Device Inlet Concentration of 20 ppm 

There are strong economic incentives for a company to maximize the concentration 

(minimize the flow rate) to a control device. Most existing facilities with open-mold spraying 

(even those without controls) currently have exhaust concentrations well above 20 ppm. 

Lowering allowable worker exposure levels can force lower concentrations to a control device. 

However, it appears likely that, even for worker exposure levels of 20 ppm, minimum exhaust 

concentrations on the order of 50-100 ppm could be achieved with current, or slightly improved, 

air flow management practices. Therefore, the assumption of a control device inlet concentration 

of 20 ppm appears to be too low. 

23 
P.35 

References 

Boyd, D., Daniel P. Boyd & Company, 1995. Presentation for the U.S. Environmental Protection 

Agency's site visit at Lasco Bathware - South Boston (VA), June 22. 

Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced 

Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, MI. 

Strum, M., U.S. Environmental Protection Agency, 1995. Site Visit Report ~ LASCO Bathware, 

South Boston, VA. 

24 
P.36 

Chapter 6 

RTI Analysis of Noneconomic Impacts of Controls 

RTFs analysis of noneconomic impacts of controls includes the development of 

normalized curves to predict noneconomic impacts. Noneconomic impacts are also calculated 

for a specific, typical existing facility that has gel coat and sprayup processes. 

6.1 Normalized Curves for Natural Gas Usage and Secondary Pollutant Emissions 

To compare energy usage and secondary pollutant emissions for various flow rates and 

styrene mass emission rates, we must "normalize" the data. Data presented in Section 6.1 have 

been "normalized" to reflect fuel usage and secondary pollutant emissions per ton of styrene 

removed (based on 95 percent removal efficiency). 

Most of the figures in this section include the following control options: (1) a thermal 

oxidizer, with 95 percent heat recovery, operating at 1,800 °F (as assumed in the SPI/CI study); 

(2) a thermal oxidizer, with 95 percent heat recovery, operating at 1,500 °F (which could produce 

a styrene destruction efficiency of 95 percent); (3) a catalytic oxidizer, with 95 percent heat 

recovery, operating at 650 °F (which could produce a styrene destruction efficiency of 

95 percent); and (4) a preconcentrator/catalytic oxidizer, based on the Polyad system, that has a 

natural gas requirement of 96,000 Btu/h at 30,000 ftVmin. (The Polyad system requires 

96,000 Btu/h to desorb styrene, for a system with an inlet flow of 30,000 ftVmin.) 

The figures in this section can be used in the following manner: In Figure 6-1, the natural 

gas usage for a thermal oxidizer operating at 1,800°F, with an inlet concentration of 20 ppm, is 

approximately 650,000 ft3 per ton of styrene removed. Therefore, if a thermal oxidizer removed 

100 tons of styrene under these conditions, the natural gas usage would be 65 million cubic feet. 

Similarly, from Figure 6-1, the natural gas usage for a preconcentrator/oxidizer operating with a 

styrene inlet concentration of 100 ppm is approximately 4,200 ftVton of styrene removed. 

Therefore, if a preconcentrator/oxidizer removed 100 tons of styrene under these conditions, the 

natural gas usage would be 420,000 ft3. 

6.1.1 Natural Gas Usage 

Figure 6-1 presents normalized curves for natural gas usage for various control options. 

Figure 6-1 also contains normalized curves for the sensible heat required to raise an exhaust 

stream from average outdoor temperatures to an indoor temperature of 75 °F for two locations 

(i.e., Fort Wayne, Indiana, and Los Angeles, California). The curves for sensible heating 

requirements are included to compare the additional natural gas usage for controls with existing 

natural gas for heating. 

In Figure 6-1, the top left point of the four control-option curves represents the 

assumptions in the SPI/CI study (i.e., a thermal oxidizer, with 95 percent heat recovery, operating 

25 
1000 

100 

TJ 

0) > 

o 

E 

a 

m. 

o 

c 

o 

mm 

tn 

"5 

c 

o 

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C 

o 

s 

o 

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ra 

3 10 

in 

a 

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to 

Z 

* ( \ 

. 

» 

s 

s 

V l 

* . '••-• -

" * 

• 

1» 

* 

* • . , 

* - J 

Then nal oxidizer (RTI: 1500oF) 

ytic oxidizer (RTI: Heat recovery = 95%, 650 oF) 

"••"Preconcentrator/oxidizer (Polyad: Desorption = 96,000 Btu/h @ 30,000 cfm) 

* fc " <. 

••s. 

~- _ 

* _ " * • -

ble heat for Los Angeles, California 

~-- — 

• -. . 

—_ — = —••— i 

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• « 

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~"~ -.-. 

» „ 

* 

« -, 

""" — .. 

*"••• -

" " • . . 

- .. 

*"'*". 

" 

20 40 60 80 100 120 140 160 

Styrene inlet concentration (ppm) 

180 200 220 240 260 

Figure 6-1. Normalized natural gas usage for various control 

options and for sensible heating of exhaust stream. 

En Chart 2 
P.38 

at 1,800 °F, with an inlet concentration of 20 ppm). The natural gas requirement for this point is 

approximately 650,000 ftVton of styrene removed. In contrast, for a preconcentrator-catalytic 

oxidizer operating at 88 ppm, the natural gas requirement is approximately 5,000 ftVton of 

styrene removed. 

Figure 6-1 illustrates that the natural gas usage for a preconcentrator/catalytic oxidizer is 

actually less than the sensible heat required to heat an equal flow rate to 75 °F, in Fort Wayne, 

Indiana, or Los Angeles, California. 

6.1.2 Carbon Dioxide Emissions 

Figure 6-2 presents normalized carbon dioxide emissions for four control-option curves. 

In Figure 6-2, the top left point of the four curves represents the assumptions in the SPI/CI study 

(i.e., a thermal oxidizer, with 95 percent heat recovery, operating at 1,800 °F, with an inlet 

concentration of 20 ppm). The carbon dioxide generated by natural gas combustion for this point 

is approximately 41 ton/ton of styrene removed. In contrast, for a preconcentrator-catalytic 

oxidizer operating at 88 ppm, the carbon dioxide generated by natural gas combustion is 

approximately 0.33 ton/ton of styrene removed. 

All of the curves in Figure 6-2 depict only the carbon dioxide emissions generated by 

burning natural gas to destroy styrene. These curves do not include the carbon dioxide created 

naturally by the degradation of styrene. Chemical stoichiometry dictates that every ton of styrene 

converts to 3.38 tons of carbon dioxide. 

6.1.3 Nitrogen Oxide Emissions 

The SPI/CI study assumed 15 ppm of nitrogen oxides (NOx) are emitted from the thermal 

oxidizer. This was based on the following numerical values, as reported by Haberlein 

(Haberlein, 1996): 

• 50-100 ppm, as reported by CVM 

• 10-15 ppm, as reported by Wheelabrator 

• 13 ppm, as reported by Tellkamp 

• <10 ppm, as reported by Huntington. 

RTFs research appears to indicate that values of less than 10 ppm are probably more 

typical for thermal oxidizers, particularly if the oxidizer operates at approximately 1,500 °F, and 

especially if the oxidizer uses technology to reduce NOx emissions, such as low-NOx burners. 

Specifically, RTFs research indicates the following: 

• Smith Engineering stated that none of the 25 installations for which they have 

NOx measurements has an average concentration over 10 ppm. 

• Durr Industries provided NOx emissions test data for two installations. Both 

installations had average NOx emissions less than 10 ppm. The time-weighted 

27 
100.00 

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c 

0) 

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o 

0 

a 

TJ 

0) 

a>. 

c 

o 

Dl 

a> . 

x 

o 

TJ 

c 

o 

Si 

10.00 

1.00 

to 

oo 

o 

v> 

c 

o 

c 

TJ 

TJ 

to 

to 

0.10 

0.01 

Z7ZZZZZ b. 

*« '* 

•:* • * 

* * • 

—-• - .. »• » 

•». , w

 « 

^ F = 

| — ^ 

— 1 J . 1 

— - — - i nermai oxiaizer (naDenein: IOUU or; 

- - - Thermal oxidizer (RTI: 1500 oF) 

ytic oxidizer (RTI: HR=95%, 650 oF) 

A Haberlein (20 ppm inlet styrene, thermal oxidizer, 1800 oF) 

• Existing plants 

^_ * •— 

* -. , 

. 

•-• • _ 

*•«. ~ - — 

*• -

" —-

* fc 

m

 m 

r--~-«. 

5—r-

-•-• ^ 

^ j\ 

-*-. . 

"* • ,. I 

20 40 60 80 100 120 140 160 

Styrene inlet concentration (ppm) 

180 200 220 240 260 

Figure 6-2. Normalized additional* carbon dioxide generated by natural gas combustion for 

various control options. 

* "Additional" means that the values do not include the 3.38 tons of C02 generated by the conversion of styrene (CjHJ to C02 (i.e., every mole of styrene 

[MW=104] generates 8 moles of carbon dioxide [MW=44]). 

J 
average N0X generation for a thermal oxidizer installed in an automotive 

application was 2.7 ppm (Gupta, 1996). 

• Process Combustion Corporation published a paper that concluded, "Various NOx 

combustion control techniques are available. With waste gases free of nitrogenbound compounds, NOx emissions from thermal oxidation can be reduced to less 

than 10 ppm." (Nutcher and Lewandowski, 1994) 

• The Institute of Clean Air Companies noted that operation of a thermal oxidizer 

should result in less than 10 ppm of NOx (Wax, 1995). 

Fewer data are available for NOx emissions from catalytic oxidizers. RTI investigation of 

this subject yielded the following: 

• Englehard Process Emission Systems (South Lyon, Michigan) published a paper 

that concluded that a catalytic oxidizer produces 0 to 2 ppm of NOx contribution 

(Gribbon, 1996). 

• The Institute of Clean Air Companies noted that catalytic oxidizers run at much 

lower temperatures than thermal oxidizers (and should therefore produce less 

NOx). 

Figure 6-3 shows normalized NOx emission curves for various control technologies. 

There are actually three NOx curves for thermal oxidation, based on three different assumptions 

for NOx outlet concentration. The top curve represents an assumption of 15-ppm outlet NOx, as 

assumed in the SPI/CI study. The middle thermal-oxidation curve represents an assumption of 

8.8-ppm outlet NOx, as quoted from Smith Engineering. The bottom thermal-oxidation curve 

represents an assumption of 2.7-ppm outlet NOx, as measured in the May 1995 testing by Durr 

(Gupta, 1996). 

6.2 Calculations for Specific Plant 

Bar graphs depicting energy use and secondary pollutant emissions are presented for a 

specific plant: the Universal Rundle plant in Ottumwa, Iowa. This plant has calculated 

characteristics as shown in Table 6-1. 

The Universal Rundle plant in Ottumwa, Iowa, has a calculated uncontrolled styrene 

exhaust concentration of 88 ppm, and a flow rate of 110,700 ftVmin. For each bar graph, there is 

one bar representing a concentration of 20 ppm and a flow rate of 487,080 ftVmin. This 487,080 

ftVmin flow rate represents the flow rate that would occur if emissions were diluted from the 

actual value of 88 ppm to the hypothetical value of 20 ppm assumed in the SPI/CI study. 

19 
1.0000 • i 

UJ 

o 

•a 

v > 

o 

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V 

m. 

a 

c 

a 

c 

o 

0> 

a 

TJ 

0) 

0) 

c 

0) 

o> 

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0.0001 

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s 

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w

 »* • 

1 H , L L 1 f 1 

Thermal oxidizer (Haberlein: 15 ppm NOx) 

_ _-j- nerma | ox j(jj z er (Smith Engineering verbal: 8.8 ppm NOx) 

- - Th ermal oxidizer (Durr Environmental testing: 2.7 ppm NOx) 

talytic oxidizer (Salem Englehard verbal: 1 ppm NOx) 

A Haberlein (Thermal oxidizer, 20 ppm inlet styrene, 15 ppm outlet NOx) 

• Existing plants 

"t-^; 

*" •-« . 

" • - . 

" ~ * -••. -

— *"*— *« 

"~ "*- —^_ 

xs—— 

. # , 

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- - «. 

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r- — . 

~~ —— 

•**- • # — . 

~-m— — 

— # _ 

- • — 

— • 

20 40 60 80 100 120 140 160 

Inlet styrene concentration (ppm) 

180 200 220 240 260 

Figure 6-3. Normalized NO„ emissions for various control options. 

f> ' Chart 1 J 
P.42 

Table 6-1. Characteristics for Specific Plant (Universal Rundle, in Ottumwa, Iowa) 

Characteristic 

Uncontrolled styrene emissions 

Assumed control efficiency 

Control device inlet concentration 

Air flow rate into control device 

Operational schedule 

Value 

328 ton/yr 

95 percent (i.e., 312 ton/yr of styrene 

removed, and resulting controlled emissions 

of 16 ton/yr). 

88 ppm 

110,700 ftVmin 

4,160h/yr 

6.2.1 Natural Gas Usage 

Figure 6-4 compares natural gas usage for several control options and for sensible heating 

for the specific plant. The bar on the left side of the page represents the natural gas that would be 

used if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in the 

SPI/CI study. All other bars represent the actual plant flow rate of 110,700 ftVmin. 

Figure 6-4 indicates that the natural gas used in annual heating for an exhaust flow of 

110,700 ftVmin is approximately 3.6 million ftVyr (based on heating requirements in Fort 

Wayne, Indiana). In contrast, the natural gas requirement for the preconcentrator/catalytic 

oxidizer option (which is based on the Polyad system), is approximately 1.5 million ftVyr. It 

should be noted that the calculated value of 3.6 million ftVyr for sensible heating of the exhaust 

stream does not reflect all the heating requirements for an FRP facility. Additional heating 

would be required to replace heat losses through the walls and ceiling of the facility. Natural gas 

might also be used for latent heating, if humidification is required during the winter. 

The calculations for natural gas usage in Figure 6-4 can be compared with total natural 

gas usage in the United States in 1995. The total natural gas usage in the United States in 1995 

was approximately 2.2 x 1013 ft3, which is approximately a factor of 100,000 times greater than 

the natural gas usage of the highest option shown in Figure 6-4. 

6.2.2 Carbon Dioxide Emissions 

Figure 6-5 presents carbon dioxide emissions for several control options for the specific 

plant. The bar on the left side of the page represents the carbon dioxide that would be produced 

if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in the 

SPI/CI study. All other bars represent the actual plant flow rate of 110,700 ftVmin. 

31 
250,000,000 

200,000,000 

c 

§> 150,000,000 

ro 

in 

3 

WI 

to 

O) 

"ro 

m. 

3 

ra 

100,000,000 

to 

3 

C 

to 

50,000,000 

ONatural gas used in oxidation, cubic feet/year 

• Natural gas used in sensible heating, cubic feet/year 

Thermal 

(1800 oF), 

20 ppm sty 

487,080 cfm 

Thermal 

(1800 oF), 

88 ppm sty 

110,070 cfm 

Thermal 

(1,500 oF), 

88 ppm sty 

110,700 cfm 

^^^^^ J 

Catalytic 

(650 oF), 88 

ppm sty 

110,700 cfm 

esss a 

Concentrator 

+ Catalytic, 

88 ppm sty 

110,700 cfm 

Figure 6-4. Natural gas usage for various control options and for sensible heating at a typical 

plant (basis: 328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr) 

sty = inlet styrene concentration NGbar, Chart 1 *» u 
16,000 

14,000 

12.000 

10,000 

•5 

o 

of 

% 8,000 

to 

E 

e 

o" 

O 

LO 

6,000 

4,000 

2,000 

0 4 

DC0 2 from natural gas used in oxidation, tpy 

S C02 from natural gas used in heating, tpy 

0CO2 from styrene decomposition, tpy 

Thermal 

(1800 oF), 

20 ppm sty 

487,080 cfm 

Thermal 

(1800 oF), 

88 ppm sty 

110,070 cfm 

Thermal 

(1.500 oF), 

88 ppm sty 

110,700 cfm 

Catalytic 

(650 oF), 88 

ppm sty 

110,700 cfm 

Concentrator 

+ Catalytic, 

88 ppm sty 

110.700 cfm 

Figure 6-5. Carbon dioxide emissions for various control options at a typical plant (basis: 

328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr). 

sty = inlet styrene concentration C02bar Chart 1 
P.45 

Each bar in Figure 6-5 has three components: 1) the C02 produced by natural gas used in 

oxidation, 2) the C02 that would be produced by burning natural gas to heat the flow stream from 

the average outdoor temperature to 75 °F, and 3) the C02 produced from the stoichiometric 

degredation of styrene to C02 (and water). 

The bar on the left side of the figure represents the C02 that would be produced assuming 

straight thermal oxidation of a 20 ppm flow stream. In order to reduce the concentration from 

the actual value of 88 ppm, it would be necessary to increase the exhaust flow from the actual 

value of 110,700 ftVmin to a hypothetical value of 487,080 ftVmin. The total C02 produced in 

this hypothetical situation would be over 14,000 tons/yr, of which approximately 12,000 tons/yr 

would be due to natural gas used for oxidation. 

Other bars in Figure 6-5 reflect the actual exhaust conditions for the plant 

(110,700 ftVmin at 88 ppm). The bar on the far right presents the C02 emissions from a 

preconcentrator/catalytic oxidizer. A preconcentrator/oxidizer is the control that would be most 

likely to be selected for a flow stream of 110,700 ftVmin at 88 ppm, due to the fact that the 

preconcentrator/oxidizer has a lower total annualized cost than the other options. For a 

preconcentrator/oxidizer, the total C02 emissions are approximately 1,400 tons/yr. The vast 

majority of these emissions (over 1,100 tons/yr) are due to the stoichiometric degredation of 

styrene to C02. Only 90 tons/yr of C02 emissions are due to combustion of natural gas used in 

heating the air for desorption. 

6.2.3 Nitrogen Oxide Emissions 

Figure 6-6 presents NOx emissions (as N02) for several control options for the specific 

plant. The bar on the left side of the page represents the NOx emissions that would be produced 

if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in SPI/CI 

study. All other bars represent the actual plant flow rate of 110,700 ftVmin. 

The bar on the right, which is barely visible, indicates NOx emissions for a 

preconcentration/catalytic oxidation system. A preconcentration/oxidation system would be the 

most likely control choice for a flow rate of 110,700 ftVmin, containing 88 ppm styrene, due to 

lower total annualized cost. The NOx emissions for this control option at this facility would be 

0.09 tons/yr. This can be contrasted with the estimated styrene removal of 312 tons/yr. 

6.2.4 Radon Emissions 

Figure 6-7 presents radon emissions from natural gas combustion for several control 

options for the specific plant. The bar on the left side of the page represents the radon emission's 

that would be produced if the flow rate were raised to 487,080 ftVmin, producing the 20 ppm 

value assumed in the SPI/CI study. All other bars represent the actual plant flow rate of 110,700 

ftVmin. 

34 
Ul 

1^1 

120 

100 

o. 

** 

tn 

c 

o in 

tn E 

oi 

X 

O z 

Thermal 

(1800 oF), 

20 ppm sty 

487,080 cfm 

Thermal 

(1800 oF), 

88 ppm sty 

110,070 cfm 

m\ 

Thermal 

(1,500 oF), 

88 ppm sty 

110,700 cfm 

Catalytic 

(650 oF), 88 

ppm sty 

110,700 cfm 

Concentrator 

+ Catalytic, 

88 ppm sty 

110,700 cfm 

Figure 6-6. NOx emissions for various control options at a typical plant (basis: 328 ton/yr 

uncontrolled styrene emissions and 4,160 operating h/yr) 

Tl 

O) 
o 

a 

« 

c 

o 

c 

to 

TJ '5 

o 

_c 

TJ 

01 

in 

3 

in to 

o> 

2 

3 

120,000 

100,000 

80,000 

60,000 

ui 

0\ 

| 40,000 

TJ 

0) 

c 

E 

c 20,000 

o 

TJ 

10 OC 

Thermal 

(1800 oF), 

20 ppm sty 

487,080 cfm 

Thermal 

(1800 oF), 

88 ppm sty 

110,070 cfm 

Thermal 

(1,500 oF), 

88 ppm sty 

110,700 cfm 

Catalytic 

(650 oF), 88 

ppm sty 

110,700 cfm 

Concentrator 

+ Catalytic, 

88 ppm sty 

110,700 cfm 

Figure 6-7. Radon emissions due to natural gas combustion for various control options at a 

typical plant (basis: 328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr). 

sty = inlet styrene concentration Rador Chart 1 

13 
P.48 

The radon emission calculations in Figure 6-7 are based on an average radon content of 

20 pCi/L in natural gas as assumed in the SPI/CI study. This value was also used in a study of 

radionuclide emissions from natural-gas fired steam-electric generating plants (Nelson, 1995). 

According to the Institute for Clean Air Companies, the Institute for Gas Technology reports 

radon levels typically less than 1 pCi/L (Wax, 1996). 

6.3 Conclusions 

Calculations of noneconomic impacts in the SPI/CI study were based on an exhaust 

stream containing 20 ppm of styrene, directed to a thermal oxidizer. However, for economic 

reasons, it would be unlikely that a new plant would be designed with a 20-ppm exhaust stream 

directed to an end-of-pipe control device. And, if a new plant were designed with a 20-ppm 

exhaust stream directed to a control device, a preconcentration/oxidation system would probably 

be chosen over straight thermal oxidation, again for economic reasons. 

Natural gas usage and secondary pollutant emissions were found to be considerably less 

for preconcentration/oxidation systems than for thermal oxidation, in the range from 0 to 

approximately 300 ppm of styrene. Since preconcentration/oxidation systems appear to have 

lower annualized costs than straight thermal oxidation in this range, the choice of 

preconcentration/oxidation systems in this range lowers both economic and noneconomic 

impacts. 

References 

Gribbon, S. T. 1996. Englehard Process Emission Systems; "Regenerative Catalytic 

Oxidation," Presented at the 1996 Air & Waste Management Association Specialty Conference 

"Emerging Solutions to VOC and Air Toxics Control" Clearwater, FL. 

Gupta, A., Durr Industries, Inc., A facsimile on RTO Performance and NOx to Madeleine Strum, 

U.S. Environmental Protection Agency, August 6, 1996. 

Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced 

Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, MI. 

Nelson, C, Estimates of Health Risks Associated with Radionuclide Emissions from FossilFueled Steam-Electric Generating Plants, EPA-402/R-95-16 (NTIS PB96-139753), August 1995. 

Nutcher, P. B. and D. A. Lewandowsi. 1994. Process Combustion Corporation; "Maximum 

Achievable Control Technology (MACT) for NOx Emissions from VOC Thermal Oxidation," 

AWMA paper number 94-WA74A.03, in Proceedings for the Air and Waste Management 

Association 87th Annual Meeting and Exhibition, Cincinnati, OH. 

Wax, M., Institute of Clean Air Companies, memorandum to Madeleine Strum, U.S. 

Environmental Protection Agency, August 11, 1995, Subject: Reinforced Plastic Composites. 

37 
P.49 

Wax, M., Institute of Clean Air Companies, memorandum to Mark Bahner, Research Triangle 

Institute, October 15, 1996, Subject: Radon Concentration in Natural Gas. 

38 
P.50 

Appendix A 

Comments on Individual Statements in the SPI/CI Study 

39 
P.51 

Appendix A 

Comments on Individual Statements in the SPI/CI Study (Haberlein, 1996) 

1) The (catalytic oxidizer) bed temperature is maintained at about 600 °C (1,100 °F) during 

normal operation. (Page IU-2). 

A more typical temperature range for catalytic oxidation of styrene is 600-700°F (Patkaf 

etal., 1994). 

2) The problem (of catalyst poisoning in a catalytic oxidizer) is severe and unpredictable... 

(Page m-2). 

A July 19, 1996 memorandum from Michael Wax (Institute of Clean Air Companies) to 

Madeleine Strum (EPA-OAQPS) states that catalyst plugging, poisoning, and 

deactivation are well understood, and may be ameliorated through appropriate system 

design and operating practices. He refers to an article in the September 1994 issue of 

Chemical Engineering, "Extend the Life of Pollution Control Catalysts," that discusses 

in-situ catalyst rejuvenation as an alternative to catalyst replacement. 

3) A thermal regenerative incinerator was selected for the hypothetical plant 

(30,000 ft3/min, 20ppm styrene, 8,760 h/yr, 43 tons uncontrolled styrene emissions) 

because this type of incinerator has been shown to be the most cost-effective type of 

control compared to the recuperative or catalytic (recuperative) types. (Page IJJ-3). 

This analysis ignores the option of preconcentration/oxidation, which appears to have a 

lower total annualized cost than any of these options (including regenerative thermal 

oxidation), for the hypothetical inlet conditions. 

4) For the hypothetical incinerator discussed above...at an oxidation temperature of 

1800 °F... (Page D3-5). 

A thermal oxidation temperature of 1,800 °F is compatible with Haberlein's assumed 

styrene destruction efficiency of 99 percent. A lower thermal oxidation temperature, such 

as 1,500 °F, would be compatible with a lower destruction efficiency, such as 95 percent. 

5) The supplemental fuel requirement for an incinerator (with 95 percent heat recovery) 

operating at an exhaust flow rate of 30,000 cfm at 20 ppm VOC (and 1,800 °F) is 

3,310,000 Btu/h. (Page D3-5). 

The RTI cost spreadsheet for a thermal oxidizer under these conditions produces a 

calculated supplemental fuel requirement of 2,984,000 Btu/h, or approximately 

10 percent less. This represents fairly close agreement. 

40 
6) Annual electrical consumption (for the hypothetical thermal oxidizer) is 1,230,000 kWh 

(over 8,760 hours). (Page ffl-6). 

This represents power usage of 140 kW/h. The RTI cost spreadsheet for a thermal 

oxidizer (with 95 percent heat recovery) under these conditions is 125 kW/h, or 

approximately 10 percent less. This represents fairly close agreement. RTFs calculation 

was based on quotations from Salem Englehard (Mack, 1996). 

7) Unfortunately, these compounds (catalyzed resin aerosols and polystyrene-forming 

agents) are indeed present in the exhaust streams at most plants, as evidenced by the 

solid plastic residue that coats the inner surface of the ductwork in many locations. 

Further, no effective means of removing all of these airborne compounds is presently 

known. (Page UJ-13). 

Catalyzed resin aerosols are present in many plants, due to spraying operations. These 

resin aerosols are actually quite large, and are therefore easily removed by even coarse 

filtration. For example, RTI mass-balance testing conducted in June 1995 indicated 

approximately 99 percent particle collection by a thin fiberglass veil. It could be expected 

that the fiberglass filter pads used at most plants would have an even higher collection 

efficiency. RTI has observed that casual fiberglass filter pad installation at many plants 

allows gaps or holes in the filter banks. This practice can dramatically lower collection 

efficiency, and would need to be avoided. Styrene gas (which can form polystyrene) is 

indeed present, and cannot be removed by physical filtration. However, Durr Industries 

reports having rotary concentrator systems in Japan that have been running for over 10 

years without styrene polymerization. 

8) The report (on Polyad) shows an annual 10 % Bonopore (adsorbent) loss out of the 

system's cyclone separator. (Page IU-14) 

Weatherly, Inc. (manufacturers of Polyad), in a July 18, 1996, memorandum to Madeleine 

Strum (EPA-OAQPS), indicated that they now guarantee annual Bonopore loss of 

5 percent or less. 

9) The calculated energy requirements for a 30,000 scfm Polyad concentrator system are 

130 kW, and 96,000 Btu/hr. (Page UI-15). 

Weatherly, Inc. (manufacturers of Polyad), in a 1996 memorandum to Madeleine Strum 

(EPA-OAQPS), indicated that the electrical requirement would actually be 62 kW, but 

the natural gas usage value was correct. 

References 

Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced 

Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, MI. 

41 
L53 

Mack, S., Englehard Corporation, A facsimile on RCO Costs to Mark Bahner, Research Triangle 

Institute, February 8, 1996. 

Patkar, A.N., J.M. Reinhold, and G. Henderson. 1994. "Demonstration of Capture and Control 

Efficiency for a Styrene Emission Source," Paper number 94-RAl 11.03, in Proceedings for the 

Air and Waste Management Association 87th Annual Meeting and Exhibition, Cincinnati, OH. 

42 
P.54 

Appendix B 

Revision of the Styrene Control Cost Spreadsheet Model and Cost Figures 

43 
P.55 

RESEARCH TRIANGLE INSTITUTE /RT 

Center for Environmental Analysis 

MEMORANDUM 

DATE: October 9, 1996 

TO: Norman Kaplan, EPA/APPCD/MD-04 cc: Emery Kong (541-5964) 

Madeleine Strum, EPA/OAQPS/MD-13 

FROM: Mark Bahner (541-6016) iAf\b 

SUBJECT: Errors in Styrene Control Cost Spreadsheets and Cost Figures. 

Contract 68-D1-0118 (Option IV), work assignment 156. (RTI project 6173-156). 

Contract 68-D 1-0118 (Option V), work assignment 192. (RTI project 6684-192). 

As a result of activities conducted to prepare an Addendum to the report, "Assessment of 

Styrene Controls for FRP/C and Boat Building Industries" (EPA-600/R-96-109), I have discovered 

errors in the styrene control cost spreadsheets and in cost curves presented in the report. I do not 

believe that these errors significantly affect the accuracy of the spreadsheet total annualized cost 

calculations, or alter conclusions of the report. Therefore, per a telephone conversation with 

Norman Kaplan today, RTI will not attempt to revise the affected portions of EPA-600/R-96-109. 

The errors in the cost spreadsheets are as follows: 

1) Polyad System - The cost spreadsheet for the Polyad system was based on electrical 

usage of 22 kW at 5,000 cfm, and 59 kW at 15,000 cfm. Weatherly, Incorporated (manufacturer of 

Polyad) informed me in December 1995 that actual values would be 12 kW at 5,000 cfm and 32 

kW at 15,000 cfm. However, I neglected to change the spreadsheet accordingly. Additionally, the 

Polyad cost spreadsheet has a fuel usage of "zero" for all conditions. This was a simplifying 

assumption: a more accurate representation would be 48,000 Btu/hr at 15,000 cfm. 

These two errors actually tend to bias the total cost calculations in different directions, and 

therefore nearly cancel each other out, in terms of final cost. The incorrect and corrected values for 

a range of concentrations, and input mass rates (in tons per year) are shown in Table 1. 

44 

3040 Cornwall,s Road • Post Office Box AA± - Research Triangle Park, North Carolina 27709-219^ USA 

T

eiepnor.e 9'9 5^1-5382 • Fax 919 541-7155 
. P56 

Table 1. Corrected Cost/Ton Values for the Polyad System. 

Input 

mass 

400 TPY 

400 TPY 

100 TPY 

100 TPY 

20 TPY 

20 TPY 

Correct 

Incorrect 

Correct 

Incorrect 

Correct 

Incorrect 

Inlet concentration, ppm 

50 

3,473* 

3,702 

4,622 

4,853 

8,945 

9,191 

100 

1,998 

2,113 

2,771 

2,889 

6,946 

7,079 

150 

1,432 

1,512 

2,246 

2,322 

6,196 

6,290 

200 

1,156 

1,213 

1,967 

2,027 

5,802 

5,878 

300 

844 

883 

1,663 

1,705 

5,395 

5,451 

500 

613 

637 

1,389 

1,416 

5,059 

5,101 

700 

522 

539 

1,261 

1,218 

4,912 

4,947 

* Cost ($) per ton of styrene removed. 

2) Durr rotary concentrator system - Cost and fuel usage data for the Durr rotary 

concentrator were received very near the end of the. original styrene controls assessment project. 

I had time to accurately model accurate equipment costs for the Durr rotary concentrator, but I did 

not have time to accurately model fuel usage. (The most accurate model of fuel usage for the 

system would be based on basic principles of combustion and heating.) The fuel usage calculations 

generally over-estimated fuel usage. Knowing that the fuel usage numbers were probably 

inaccurate, I left out the fuel cost from the final Total Annualized Cost calculation. 

Since fuel cost was actually removed from the Total Annualized Cost calculation, the cost 

spreadsheet for the Durr rotary concentrator actually underestimates cost slightly. The incorrect and 

corrected values are shown in Table 2. 

Table 2. Corrected Cost/Ton Values for the Durr Rotary Concentrator System. 

Input 

mass 

400 TPY 

400 TPY 

100 TPY 

100 TPY 

20 TPY 

20 TPY 

Correct 

Incorrect 

Correct 

Incorrect 

Correct 

Incorrect 

Inlet concentration, ppm 

50 

3,494* 

3,482 

4,493 

3,945 

6,569 

6,022 

100 

1,870 

1,870 

2,404 

2,213 

4,563 

4,373 

150 

1,352 

1,280 

1,721 

1,649 

3,898 

3,827 

200 

998 

986 

1,382 

1,371 

3,567 

3,555 

300 

696 

696 

1,094 

1,094 

3,283 

3,283 

500 

469 

469 

875 

875 

3,067 

3.067 

700 

372 

372 

781 

781 

2,974 

2,974 

Cost ($) per ton of styrene removed. 

45 
P.57 

3) Figure 5-5, "Cost curves for a large plant (400 tons per year inlet)" in 

EPA-600/R-96-109 has cost curves for three control technologies plotted on a right-hand axis. This 

right-hand axis is incorrectly scaled with a minimum of negative $1,000/ton. The affected 

technologies are the EC&C fluidized-bed preconcentrator, the Durr rotary concentrator, and the 

VOC condenser: If these technologies are plotted with a minimum cost of $0/ton, similar to other 

technologies in Figure 5-5, the resulting curves are somewhat altered. 

I have attached a revised version of Figure 5-5. The new figure contains revised curves as 

they would appear, assuming the EC&C preconcentrator is desorbed into a thermal oxidizer. The 

version of Figure 5-5 that appears in EPA-600/R-96-109 is also attached, with the notation 

"ORIGINAL (INCORRECT)". 

I have included a diskette with (revised) cost spreadsheets. If you have any questions, please 

call me at 541-6016. 

46 
^1 

c 

o 

TJ" If cu c *: CU f £ II S c 

<4- O o «r *: ** 

3 k. OJ O L co 

o 

O 

n nnn -* 

Q nnn -

A nnn -

7,000 -

fi nnn 

o,uuu -

5,000 -

A nnn 

•t.uuu - i nnn 

J,UUU -

o nnn 

<c,uuu -

1.000 - 0 -

246.000 

123,000 

I 

\ 

\ 

K V Vi w 

V 

• • \ 

\ 

^^ A 

*<£ >< 

Flow rate.cfm (1 cfm = 0.0283 m3/min) 

61.500 41.000 30.750 24,600 

i 

• 

t 

• 

» 

« 

i 

> > . ^b 

^ ' \ 

% 

^ * ^ %^p V 

• 

1 

«-»..^ 

20,500 17.6 

1 1 1 I I 1 1 

MIAB 

" - - Polyad (w/oxidation) 

Catalytic oxidizer (95% H.R. below 100 ppm) 

Thermal oxidizer (95% H.R. below 100 ppm) 

Biofiltration 

Thermatrix PADRE 

— -

"•- . 

-tr-— 

•Durr rotary concentrator 

•VOC condenser 

EC&C fluidized-bed preconcentrator (w/oxidation) 

"'••. . 

""••. • .. 

*£^^ M 

"*-- . 

" * - • _ 

"" * * . 

« , , , 

100 200 300 400 

Concentration (ppm) 

500 600 700 

Figure 5-5. Cost curves for a large plant (400 tons per year inlet). 

J 
oo 

O «; 

•a* 

9) If 

at $ *• _ c *T CO T - >. II t) c *- o o «t 

3 0) a. 

* rf (A 

o 

u 

m nnn ^ 

Q nnn -

8,000 -

7.000 -

6,000 -

5.000 -

4.000 -

3,000 -

2,000 -

1,000 • 0 -

246,000 

123 

i 

\ 

\ 

«\ 

i\\ 

TO vv V J 

^ 

V 

000 

• 

1 

\ 

A 

Flow rate.cfm (1 cfm = 0.0283 m3/min) 

61,500 41.000 30,750 24,600 

* * 

i 

• 

t 

* 

* 

* 

^ 

^ ^ ^ 

* 

% 

* * > S **t. 

% 

. ^ 

20,500 

1 1 1 ll l l 

MIAB 

- - - Polyad (w/oxidation) 

Catalvtic oxidizer f95% H.R. below 100 DDmi 

— -

- - Thermal oxidizer (95% H.R. below 100 ppm) 

— - Biofiltration 

- - Thermatrix PADRE 

•"Rot di

y uunueiiuaiui 

C condenser 

— - EC&C fluidized-bed preconcentrator 

'••'. . 

3~- — 

"*•.._ 

- !•-.•-

-• •, 

* * • • 

- — 

*•-... — — 

— -

*"•-. . M 3 

17.6 -

• 

. 

• 

* -.. 

J»_j— — 

100 200 30

0 400 

Concentration (ppm) 

500 600 700 

Figure 5-5. Cost curves for a large plant (400 tons per year inlet). ORIGINAL (INCORRECT) 

Jo 
P.60 

EPA-6007K-96-136 

November 1996 

Addendum to Assessment of Styrene 

Emission Controls for FRP/C and 

Boat Building Industries 

Final Report 

by: 

Emery J. Kong, Mark A. Bahner, and Sonji L. Turner 

Research Triangle Institute 

P.O.Box 12194 

Research Triangle Park, NC 27709 

EPA Contract 68-D1-0118, W.A. 192 

EPA Project Officer: Norman Kaplan 

Air Pollution Prevention and Control Division 

National Risk Management Research Laboratory 

U.S. Environmental Protection Agency 

Research Triangle Park, NC 27711 

Prepared for 

U.S. Environmental Protection Agency 

Office of Research and Development 

Washington, DC 20460 
P.61 

Abstract 

This report is an addendum to a 1996 EPA report entitled Assessment of Styrene Emission 

Controls for FRP/C and Boat Building Industries. This addendum presents additional evaluation 

of the biological treatment of styrene emissions, Dow Chemical Company's SORBATHENE® 

solvent vapor recovery system, Occupational Safety and Health Administration regulations and 

other policies that affect the fiber reinforced plastics/composites (FRP/C) and boat building 

industries, and secondary pollution and natural gas usage resulting from various emission control 

options. 

This study concludes that: 

• Based on available results from bench- and pilotrscale studies and full-size 

operation, biofiltration or a bioscrubber could be a viable control option for 

treatment of styrene emissions. 

Dow Chemical's SORBATHENE® vapor recovery system was developed for 

high-concentration, low-flow exhaust from storage vents and would not be 

economically feasible for low-concentration, high-volume flow typically found in 

the most prominent processing techniques in the FRP/C and boat building 

industries. 

• Employers should comply with current or future permissible exposure limits 

(PELs) for styrene using feasible engineering controls and should provide 

respiratory protection to employees when worker exposure cannot meet PELs 

after feasible engineering controls have been implemented. It is also an industrial 

practice for employers to provide additional respiratory protection to the 

employees even though the PELs are met. 

• Direct thermal oxidation or catalytic oxidation would be less economical than 

preconcentration/oxidation technologies for low-concentration, high-volume 

emissions typically found in the industries. Secondary pollution and natural gas 

usage could be reduced significantly when using preconcentration technologies 

followed by catalytic oxidation. 

u 
P.62 

Contents 

Abstract ii 

Figures v 

Tables v 

Acronyms and Abbreviations vi 

Conversion Table viii 

Chapter 1 Introduction 1 

References 1 

Chapter 2 ' Biological Treatment 2 

2.1 System Infonnation Requested .. . * 2 

2.2 Descriptions of Biological Treatment Systems 2 

References 8 

Chapter 3 Novel Styrene Emission Control Technology 9 

3.1 Dow Chemical SORBATHENE® Solvent Vapor Recovery Unit 9 

References 11 

Chapter 4 OSHA Regulations and Policies Affecting Worker Exposures in the FRP/C and 

Boat Building Industries 12 

4.1 Summary and Implication of OSHA Regulations 12 

4.2 De Minimis Violations 13 

4.3 Local Air Flow Management and Spray Booth Modifications 14 

References 15 

Chapter 5 Assumptions in the Society of Plastics Industry/Composites Institute's (SPI/CI) 

Study on Noneconomic Impacts of Incineration Controls 17 

5.1 Use of Thermal Oxidizer 17 

5.2 Control Device Inlet Concentration of 20 ppm 17 

5.2.1 Economic Incentives for Maximizing Inlet Concentrations 19 

5.2.2 Exhaust Concentrations at Existing Plants 19 

5.2.3 Recent and Potential Future Changes in Allowable Exposures to Styrene21 

5.2.4 Existing Relationships Between Worker Exposure and Exhaust 

Concentration 21 

5.2.5 Potential Methods to Increase Concentration to Downstream Controls . 21 

5.2.6 Conclusions on Assumption of Control Device Inlet Concentration of 20 

ppm 23 

References 24 

Chapter 6 RTI Analysis of Noneconomic Impacts of Controls 25 

6.1 Normalized Curves for Natural Gas Usage and Secondary Pollutant Emissions 25 

6.1.1 Natural Gas Usage 25 

iii 
P.63 

Contents (continued) 

6.1.2 Carbon Dioxide Emissions 27 

6.1.3 Nitrogen Oxide Emissions 27 

6.2 Calculations for Specific Plant 29 

6.2.1 Natural Gas Usage 31 

6.2.2 Carbon Dioxide Emissions 31 

6.2.3 Nitrogen Oxide Emissions 34 

6.2.4 Radon Emissions 34 

6.3 Conclusions 37 

References 37 

APPENDIXES 

A Comments on Individual Statements in the SPI/CI Study 39 

B Revision of the Styrene Control Cost Spreadsheet Model and Cost Figures 43 

iv 
P.64 

Figures 

No. Page 

2-1 W K Weege GmbH bioscrubber system 7 

3-1 Process diagram of a SORBATHENE solvent vapor recovery unit 10 

5-1 Cost curves for a large plant (400 tons per year inlet) 18 

5-2 Typical open molding operation in a spray booth 22 

6-1 Normalized natural gas usage for various control options and for sensible heating 

of exhaust stream *. 26 

6-2 Normalized additional carbon dioxide generated by natural gas combustion for 

various control options ., 28 

6-3 Normalized NOx emissions for various control options 30 

6-4 Natural gas usage for various control options and for sensible heating at a typical plant 32 

6-5 Carbon dioxide emissions for various control options at a typical plant 33 

6-6 Nox emissions for various control options at a typical plant 35 

6-7 Radon emissions due to natural gas combustion for various control options at a typical 

plant 36 

Tables 

No. ' Page 

2-1 Properties for Styrene Abatement Biosystems 4 

5-1 Styrene Exhaust Concentrauons at Existing Open Molding Plants with Resin/Gel Coat 

Usage Greater than 1,000 ton/yr .20 

5-2 Comparison of average styrene exhaust concentration (290 ppm) with worker exposure 

levels at Lasco Bathware, South Boston, VA 23 

6-1 Characteristics for Specific Plant (Universal Rundle, in Ottumwa, Iowa) 31 
P.65 

Acronyms and Abbreviations 

ACGIH American Council of Government Industrial Hygienists 

BACT best available control technology 

Btu British thermal unit 

CAAA Clean Air Act Amendments of 1990 

CE capital equipment (cost) 

CEFIC Unsaturated Polyesters Sector Group of European Chemical Industry Council 

CFCs chlorofluorocarbons 

CO carbon monoxide 

C02 carbon dioxide 

EC equipment cost 

EC&C Environmental C&C, Inc. 

EPA Environmental Protection Agency 

FID flame ionization detector 

FRP/C fiber-reinforced plastics/composites 

ft feet 

ft/min feet per minute 

GPRMC European Organization of Reinforced Plastics/Composite Materials 

HAP hazardous air pollutants 

H.R. heat recovery 

kW kilowatt 

kWh kilowatt-hour 

lb pound 

Ib/h pounds per hour 

LEL lower explosive limit 

MACT maximum achievable control technology 

MIAB Molnbacka Industri, AB 

NFPA National Fire Protection Association 

NOx nitrogen oxides 

OAQPS Office of Air Quality Planning and Standards 

OSHA Occupational Safety and Health Administration 

PADRE Polymer Adsorption and Removal 

PC personal computer 

PEC purchased equipment cost 

PEL permissible exposure limits 

ppm parts per million (by volume) 

PSA pressure swing adsorption 

psig pounds per square inch, gage 

REECO Regenerative Environmental Equipment Co., Inc. 

RPC reinforced plastic composites 

RTI Research Triangle Institute 

SIC Standard Industrial Classification 

SMC sheet molding compound 

vi 
P.66 

SPI/CI 

STC 

STEL 

TCI 

TDC 

TLV 

ton/yr 

TRI 

TVA 

TWA 

VOC 

vr 

°C 

°F 

Society of the Plastics Industry/Composites Institute 

Southeastern Technology Center 

short-term exposure limit 

total capital investment 

total direct cost 

threshold limit value 

tons per year 

Toxics Release Inventory 

Tennessee Valley Authority 

time-weighted average 

volatile organic compound 

year 

degrees Celsius , 

degrees Fahrenheit 

vn 
P.67 

Conversion Table 

2 rl .

EnVlr0nmenta l Protectlo n A g^cy policy is to express all measurements in Agencv 

documents in metric units. In this report, however, to conform to industrial Tonveiti^n EnL ^ 

units are used. Converse factors from English to metric units are given be 0w 

English Unit 

Btu 

°F 

ft 

s 

ft2 

ft3 

ftVmin (cfm) 

gal/min 

inch 

in. H;0 

lb 

psia 

ton 

iTtuiu(jiy o y 

1.055xl03 

(°F-32)/1.8 

0.3048 

0.0929 

0.0283 

0.028314 

3.79 -

2.54 

1.87 

0.454 

6.895 

0.907 

To Obtain 

joule 

m 

nr 

m

J 

mVmin 

l/min 

cm 

mmHg 

kg 

kilopascal 

Mg 

vm 
Chapter 1 

Introduction 

The 199Q Clean Air Act Amendments (CAAA) mandate the development and 

promulgation of standards for hazardous air pollutants (HAP) emitted from a multitude of source 

categories by the year 2000. Styrene is listed as a HAP in the CAAA, and it is known to be 

emitted from the fiberglass-reinforced plastics/composites (FRP/C) and boat building industries. 

An earlier study (Kong et al., 1996) assessed the available control technologies, their efficiencies, 

performance, and cost. That study also reviewed and summarized Occupational Safety and 

Health Administration (OSHA) regulations governing the worker exposure issues, and presented 

the air flow management practices that could achieve cost-effective control of styrene emissions. 

This report presents additional evaluation of the biological treatment of styrene 

emissions, Dow Chemical Company's SORBATHENE® solvent vapor recovery system, OSHA 

regulations and other policies that affect the FRP/C and boat building industries, and secondary 

pollution and natural gas usage resulting from various emission control options. 

This study concludes that: 

1. Based on available results from bench- and pilot-scale studies and full-size operation, 

biofiltration or a bioscrubber could be a viable control option for treatment of styrene emissions. 

2. Dow Chemical's SORBATHENE® vapor recovery system was developed for highconcentration, low-flow exhaust from storage vents and would not be economically feasible for 

low concentration, high-volume flow typically found in the most prominent processing 

techniques in the FRP/C and boat building industries. 

3. The employers should comply with current or future PELs for styrene using feasible 

engineering controls and should provide respiratory protection to the employees when worker 

exposure can not meet PELs after feasible engineering controls have been implemented. It is 

also an industrial practice for employers to provide additional respiratory protection to the 

employees even though the PELs are met. 

4. Direct thermal oxidation or catalytic oxidation would be less economical than 

preconcentration/oxidation technologies for low-concentration, high-volume emissions typically 

found in the industries. Secondary pollution and natural gas usage could be reduced significantly 

when using preconcentration technologies followed by catalytic oxidation. 

References 

Kong, E.J., M.A. Bahner, and S.L. Turner. September 1996. Assessment of Styrene Emission 

Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640), 

Research Triangle Park, NC. 

l 
P.69 

Chapter 2 

Biological Treatment 

Biological treatment uses microorganisms in a medium, usually a biofilter or bioscrubber, 

to destroy organic compound emissions in an air stream. Air emissions containing biodegradable 

constituents pass through a biologically active medium. The microorganisms degrade the 

organic constituents in the air stream to essentially carbon dioxide and water. Biofiltration has 

been used for many years in Europe, Japan, and the United States for odor control, but the use of 

biofiltration to degrade more complex air emissions from chemical plants has occurred only 

within the last few years. Descriptions of biofiltration and biotrickling filter systems are 

presented in an EPA report (Kong et al., 1996). Biofiltration and biotrickling filter are similar in 

principle, but different vendors use different designs and rrfedia. This addendum includes 

another new biological treatment system which comprises a bioscrubber and a bioreactor. This 

section presents the process descriptions and information for several biological treatment units 

that have been tested or applied for styrene emissions. 

2.1 System Information Requested 

The Research Triangle Institute (RTI) contacted seven researchers and suppliers to obtain 

available information on their various existing and proposed biological treatment systems. The 

request included but was not limited to information on the following: 

• flow rates * • composition of the bio-medium 

• emission source • incubation period of the bio-medium 

• concentration • size of the biofilter 

• capture efficiency • pressure drop 

• control efficiency • acclimation period 

• time of operation (hours/day, days/week) • performance during startup 

• number of persons required for operation • performance after periods of shutdown 

• frequency of regeneration • capital and operating costs 

Five facilities responded by the requested deadline to provide information for this report: 

Envirogen, Tennessee Valley Authority (TVA), W K Weege GmbH, Southeastern Technology 

Center (STC), and EnvirOzone, Inc. 

2.2 Descriptions of Biological Treatment Systems 

Envirogen. Envirogen provided information for two units, a pilot-scale biofilter and a proposed 

full-scale biotrickling filter. The pilot-scale biofilter was tested on air discharged from a 

fiberglass spray booth operation. The full-scale biotrickling filter was designed to control styrene 

emissions generated by a sequence batch reactor in a chemical company's wastewater treatment 

facility; however, the system was never put into service. Currently, CVT Bioway is conducting a 

field pilot study with TNO in Europe. This work is confidential and remains unavailable to 
Envirogen. (Envirogen and a Dutch company have a joint venture company called CVT 

America. CVT America has potential access to license TNO's technology through a sister 

company called CVT Bioway. CVT Bioway is a separate company from CVT America.) As 

data and information from this field study become available to them, Envirogen will update RTI. 

Information on the Envirogen biotreatment system is presented in an EPA report (Kong et al., 

1996). Properties for their pilot-scale system and design specifications for their full-scale system 

are listed in Table 2-1. 

TVA. In 1989, 1.04 x IO6 kg (1,144 tons) of styrene was emitted by manufacturing industries in 

the Tennessee Valley making styrene the second largest Toxic Release Inventory (TRI) classified 

toxic chemical released in the region (Lackey et al., 1994). Laura Lackey with TVA conducted 

bench-scale and pilot-scale studies to eliminate styrene emissions from the air streams of an 

industrial partner and other varied industrial applications. For bench-scale biofilter experiments, 

a parallel series of three bench-scale 2.8-L biofilters was constructed. All three biofilters were 

packed with a 1:1 (v/v) mixture of pine bark and composted chicken litter. A stainless steel 

screen supported the packing material creating a free space at the bottom of each biofilter. A 

controlled feed of styrene-contaminated gas entered the free space, and purified air exited the top, 

For the bench-scale experiments, biofilters were operated continuously for a 7-month period. 

Biofilter 1, the Control, was autoclaved and served as a sterile control. Biofilter 2 was 

inoculated with a styrene-degrading consortium of organisms, and Biofilter 3 used only naturally. 

occurring microorganisms. Inlet styrene concentrations ranged from 50 to 4,000 ppmv and the 

empty bed contact time varied between 1 and 8 minutes. During days 29 to 36, the humidity of 

the incoming air stream was inadvertently dropped below the normal 99 percent to below 50 

percent relative humidity. This drop caused the removal efficiency of Biofilter 2 to decrease to 

60 percent. After the humidity was returned to normal, the performance of Biofilter 2 quickly 

improved and removal efficiency increased to greater than 99 percent. This problem did not 

occur with Biofilter 3. After the initial acclimation period, the performances of Biofilter 2 and 

Biofilter 3 were similar, greater than 99 percent (L.W. Lackey, TVA, personal communication, 

Sept. 4, 1996). 

The pilot-scale biofilter that was installed at a boat building manufacturing site was 0.8 

meters in diameter with a total packing volume of 1.26 m3 (Holt and Lackey, 1995). It was also 

filled with a 1:1 (v/v) mixture of pine bark and composted chicken litter. The pilot-scale, biofilter 

was monitored for 3 months. During normal manufacturing, the spray booth was operated for 

three shifts each day (20 h/d). Following the first week of operation and microbial acclimation, 

the manufacturing facility shut down for 1 week. During the shutdown, the biofilter continued to 

operate, and the system was maintained under aerobic conditions by blowing an uncontaminated 

air stream through the biofilter. Some styrene breakthrough was noted during the first shift after 

the week of downtime. However, no styrene was detected in the biofilter effluent for the next 2 

months when the empty bed contact time was maintained at a constant rate. Additional 

information about the properties for both systems is listed in Table 2-1. Lackey plans to design a 

demonstration-scale 340-m3/min (12,000-ft3/min) biofiltration system based on the results of the 

two studies. However, a decision to construct the demonstration-scale system is currently on 

hold until there are regulatory requirements to build it. 

3 
Table 2-1. Properties for Styrene Abatement Biosystems 

t 

Bioreactor 

Parameters 

Unit type 

Reactor type 

Reactor size 

Emissions source . 

Other polltitant(s) 

Plow rate 

Styrene concentrations 

Control efficiency 

Time of operation 

Persons needed for 

operation 

Media replacement 

Companies 

ENVIROGEN 

Pilot 

Biofilter 

0.85 in' 

(30 ft') mediumV 

Fiberglass spray 

booth operation 

Full-scale' 

Biofilter 

0.28 m'(10 ft') 

Wastewater 

treatment facility 

NA 

7.08 x 10' lo 

5.66 x 10' m'/s 

(15 to 120 ft'/min) 

NA 

>95% @ 30+ sec 

85% to 95 %@ 15 

sec 

16 h/d, 5 d/wk, 

4 months 

0.6608 m'/s 

(1,400 ft'/min) 

NA 

90% removal 

24 h/day 

1 

5 lo 7 years 

TVA 

Benchb Pilot 

Biofilter 

2.8xlO'm J 

(0.099 ft') 

Controlled 

contaminated feed 

Acetone 

NA 

50 to 4,000 ppmv 

(inlet) 

>99% removal 

(Biofilter 2) 

>99% removal 

(Biofilter 3) 

7 months 

1.26m' 

(44.5 ft') 

medium 

Boat 

manufacturer 

MEK 

Acetone 

2.83 x 10'lo 

2.12 x 10' 

(6 to 45 ft'/min) 

Olo 400 ppmv

 % 

(inlet) 

>98% removal 

13 months 

None 

Life of system | NA | 

W K Weege 

Full-scale 

Bioscrubber 

Designed for 

treatment required' 

Automotive parts 

production 

NAJ 

20,000 m'/li 

(11.774 ft'/min) 

50 lo 60 ppm 

(inlet) 

5 ppm (outlet) 

- 90% removal 

8 h/d. 5 d/wk, 

10.5 mo/yr 

None 

STC 

Pilot 

Biofilter 

21.62 m' 

(763.4 ft') 

FRP facility 

MEK 

0.472 to 0.944 m'/s 

(1.000 lo 2,000 

fl'/min) 

30 ppm (inlet). 

0.3 ppm (outlet) 

99% 

24 li/day 

None 

Life of system | 4 to 7 years 

(continued) 
Table 2-1. Continued 

. ° \ 

Bioreactor 

Parameters 

Unit type 

Media composition 

Acclimation period 

Pressure drop 

Startup performance 

Shutdown 

recovery 

Capital cost 

Operating cost 

Companies 

ENVIROGEN 

Pilot 

Proprietary 

engineered organic 

based material 

- 1 week 

1 in. to 2 in. H,0 .. 

@ startup 

8 in. H20 design 

75 % @ 60 sec 

5 to 8 h 

(weekend 

shutdown) 

NA 

NA 

Full-scale" 

Synthetic packing 

1 to 2 weeks 

(expected) 

< 1 in. ll 2 0 

(expected) 

NA 

NA 

Available upon 

request 

Available upon 

request 

TVA 

Bench1" Pilot 

1:1 (v/v) pine bark and composted 

chicken litter 

- 5 days (Biofilter 2) 

- 55 days (Biofilter 

3) 

0.003 in. H,0 (max) 

NA 

0.75 in. ll 2 0 

(max) 

NA 

NA 

NA 

NA 

W K Weege 

Full-scale 

Proprietary 

NA 

NA 

NA 

Vi lo 1 h 

(after shul-down) 

$450,000 lo 

$700,000 

$25/day lo 

$30/day 

STC 

Pilot 

80% chicken 

compost 

20% GAC 

2 lo 3 weeks 

20 lo 30 in. H2 0 

30 lo 70 % 

variable 

$140,000 

(w/enginecring) 

$400/month 

NA - not available. 

a. Design parameters of this systems are listed. The system currently is not in use. 

I). A parallel scries of three bench-scale biofilters were used for this bench-scale lest. Biofilter I was autoclaved and served as a sterile control. Biofilter 2 was 

inoculated with a styrene-degrading consortium of organisms. Biofiller 3 utilized only naturally occurring microorganisms. 

c. Each system is designed to handle specific waste streams. Normal height of filler material is a maximum of I lo 1.25 m. For 100 to 150 m' of emissions, 

estimate approximately I in' of filler material. 

d. System can be engineered for specific waste streams of volatile organic compound (VOCs). A series of bioscrubbers can be designed for each individual unit 

lo treat a specific VOC. 
P.73 

W K Weege GmbH. WK Weege GmbH, an engineering company in Wiesbaden, Germany, 

developed a bioscrubber system that removes styrene and other volatile organic compounds 

(VOCs) from industrial waste gases. The bioscrubber system employs a four-step process to treat 

styrene and VOC emissions from industrial waste gas. As shown in Figure 2-1, industrial waste 

gases enter a packed absorption tower where styrene is absorbed into the countercurrent flow of 

the absorbent solution (i.e., water and clean effluent from the bioreactor). The absorption tower 

consists of packing, a droplet separator, and a liquid distributor. After this step, clean air leaves 

the tower, and the styrene-laden absorbent solution is pumped into a stirred bioreactor. In the 

bioreactor, styrene is biologically degraded. After the degradation is complete, proprietary 

additives are applied to maintain the bacteria population, and the clean effluent from the 

bioreactor is pumped to the absorption tower for reuse. No sludge or solid waste is generated 

from the bioscrubber process. 

The bioscrubber system is equipped with sensors and measuring devices and a computer 

to control the operations of the system. W K Weege sells a service contract to maintain and 

operate the system. The personal computer (PC) station is the heart of data acquisition for the 

bioscrubber system. The'PC station collects all data and controls various functions of the system, 

such as refilling water to make up for evaporation loss, replenishing the additives, and 

controlling the system. Through modem communication methods, these data are communicated 

back to W K Weege. This information transfer allows W K Weege to continually, monitor the 

function of the system and to remotely adjust the system when necessary using a fax modem. 

Two bioscrubber systems exist in Germany: one is a laboratory-scale facility, the other is 

a commercial unit used by a German company using sheet molding compound (SMC) to 

manufacture automotive parts. The commercial unit operated for one year but is no longer in 

operation now. Rudi Weege, company president, provided RTI with an overview of the 

commercial unit. Information for the commercial system is provided in Table 2-1. 

The cost data in Table 2-1 for the W K Weege system are taken from published literature 

(Modern Plastics, 1996). The capital costs for a system handling 11,766 ftVmin are estimated to 

be between S450,000 and S700,000. This can be compared to estimated equipment costs and 

total capital investments of 5301,000 and $619,000, respectively, from the biofiltration cost 

spreadsheet developed in the original styrene controls assessment. Operating costs are given as 

approximately $25 to $30 per day. This can be compared with an electrical cost estimate of 

approximately $15 per day from the biofiltration cost spreadsheet (assuming electricity, cost of 

$0.06 per kWhr, operating 8 hours per day). 

W K Weege is in the process of establishing a North American subsidiary to introduce 

and commercialize their technology to the FRP composite industry and other industries emitting 

VOCs in North America. According to Weege, the system can be designed to treat various 

VOCs, with each unit dedicated to treating a specific pollutant. 

Southeastern Technology Center (STC). STC is a non-profit corporation whose mission is to 

facilitate the transfer of commercially viable technologies from the government sector to the 

business sector for the purpose of promoting economic development and creating jobs. 

6 

' 

Co 
P.74 

Clean Air 

Water 

Stirrer 

Aerator 

Reactive 

Additive 

Data Acquisition 

t 

Bioreactor 

Absorption 

Tower 

i 

Waste 

Gas 

Figure 2-1. WK Weege GmbH bioscrubber system. 

•? 
P.75 

Regina Porter at STC is conducting a pilot study for styrene removal from an FRP facility. Her 

research is being conducted under a Department of Energy (DOE) contract. Delphinus 

Engineering, Inc. and EnvirOzone, Inc., both in South Carolina, are subcontractors to STC and 

are responsible for the design and operation of the pilot-scale unit. Delphinus and EnvirOzone 

provided preliminary information for this report for a 21.62-m3 (764-ft3) pilot-scale unit that has 

been designed to treat gaseous exhausts from an FRP facility. The flow rates of the exhaust 

streams range from 0.472 to 0.944 m3/s (1,000 to 2,000 ftVmin). The biofilter media contains 10 

tons (9,070 kg) of chicken compost (80 percent chicken manure and 20 percent granular 

activated carbon) that requires a 2- to 3-week incubation period. Additional information for this 

pilot unit can be found in Table 2-1 (A. Sana, Delphinus Engineering, personal communication, 

Sept. 11,1996). 

References 

German Firm Develops Styrene-Abatement System. Modern Plastics, p. 17, March 1996. 

Holt, T., and L. Lackey.' 1995. Control of gas contaminants in air streams through biofiltration. 

Proceedings of 50th Purdue Industrial Waste Conference. 

Kong, E.J., M.A. Bahner, and S.L. Turner. September 1996. Assessment of Styrene Emission 

Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640), 

Research Triangle Park, NC. 

Lackey, L. W., M.T. Holt, J.R. Gamble, and CE. Breed. 1994. Biofilter Systems for the Control 

of Gas Contamination in Air Streams. Paper presented at the Southern States Annual 

Environmental Conference, October 20. 

B 
P.76 

Chapter 3 

Novel Styrene Emission Control Technology 

3.1 Dow Chemical SORBATHENE® Solvent Vapor Recovery Unit 

*The Dow Chemical Company developed the SORBATHENE® pressure swing adsorption 

(PSA) process in the late 1980s to recover VOCs and other valuable chemical products from 

storage, loading, and process vents. Since 1988, the Dow Chemical Company has installed 19 

SORBATHENE® units to recover hydrocarbon, chlorofluorocarbons (CFCs), chlorinated 

solvents, aromatics, and monomers. Dow Chemical has two SORBATHENE® units for recovery 

of styrene vapors from storage vents. A SORBATHENE® unit can be designed to achieve 99.9% 

VOC removal from vent streams ranging in flow rate from 20*to 3,000 ftVmin with feed 

concentrations between 1,000 and 500,000 ppm (Collick et al., 1996). The chemical components 

are recovered as a condensed. liquid. Based on the evaluation of this technology and a follow-up 

conversation with Larry Larrinaga (Radian International, personal communication, September 9, 

1996), the SORBATHENE® technology would be expensive to treat the low-styrene 

concentration (less than 200 ppm) at high flow rates (greater than 5,000 ftVmin) typically found 

in the most prominent processing technologies (e.g., sprayup and hand layup in open molding 

processes) in the FRP/C facilities. 

Process Description. The SORBATHENE® process is typically applied to recover 

organic vapors from process vents, storage tanks, and loading/unloading operations. The process 

uses PSA and the heat generated during adsorption to desorb the VOCs collected on the 

adsorbent. Adsorption is carried out at atmospheric pressure and the heat of adsorption is 

retained in the adsorption bed, then the adsorbate is desorbed at a lower pressure (i.e., under 

vacuum) using the retained heat. Optimal desorption pressures are selected between 50 and 300 

mm Hg (1 and 5.8 psig). As shown in Figure 3-1, the adsorption and desorption steps are batch 

processes that occur simultaneously in alternating twin beds to maintain steady state operation of 

the unit. During the desorption step, a fraction of the clean gas leaving the adsorbing bed is used 

as the backpurge gas for desorption. The concentrated stream of desorbed VOC is drawn through 

a vacuum system then passes through a condenser where the VOC condenses and is removed as a 

liquid. The cooling medium is selected based on the temperature required to condense the vapor. 

Control valves switch the beds over short cycle times to avoid an excessive temperature rise 

caused by the heat of adsorption. The SORBATHENE® unit is designed for the maximum 

instantaneous feed concentration and flow rate that would be expected during operation of the 

unit. The unit would not require adjustment as the inlet flow rate and concentration vary due to 

tank filling operation. 

Standard Operating Conditions. The process has been applied for vent streams ranging 

from 20 to 3,000 ftVmin concentrations between 1,000 and 500,000 ppm. The adsorbent, 

operating pressures and temperatures, and cycle time of the unit are determined in a pilot study 

based on the characteristics of the VOC to be recovered. Each unit is tailored to the specific 

VOC and the characteristics of the exhaust stream. 
P.77 

Clean Vent Stream 

Desorbing Unit 

Adsorbing Unit 

Feed Stream 

Condense 

Separator 

o*<] •' open valve 

• ^ : closed valve 

T 

Recovered 

Uquid 

: adsorbing flow 

desorbing flow 

Figure 3-1. Processdiagram of a SORBATHENE 

solvent vapor recovery unit. 

10 

i£_ 
P.78 

Control Efficiency. A SORBATHENE® unit has been tested for styrene vapor recovery 

from storage vents and its recovery efficiency was 99.78 percent for an inlet concentration of 

5,742 ppm and an outlet concentration of 13.3 ppm (Hall, 1993). The flow rate was not reported 

for this tested unit; however, exhaust flow rates from storage vents are probably in the severalhundred-ftVmin range when being filled. Polymerization was not encountered for the adsorbent 

used in these applications. 

Applicability to FRP/C/C Processes. The SORBATHENE® technology would not be 

economically feasible for the typical low-concentration and high-flow rate exhaust encountered 

in the FRP/C facilities. A SORBATHENE® unit might be used after the exhaust stream has been 

concentrated and its flow rate reduced by a preconcentration unit; however, its feasibility will be 

determined by the economic value, quantity, and reusability of the recovered styrene. 

Cost. Larry Larrinaga (Radian International, personal*communication, September 9, 

1996) estimated that the equipment costs for a SORBATHENE unit treating an optimal flow rate 

of 300 to 500 ftVmin would range from $600,000 to $800,000. The SORBATHENE® unit is 

very sensitive to flow rate and the equipment cost increases dramatically as the flow rate 

increases. Operating costs include electricity cost to operate the adsorbers, vacuum pump, 

condenser, and separator. 

References 

Collick S.J., DJ. Pezolt, and L. Larrinaga. 1996. Capture and Recovery ofTetrafluoromethane 

and Hexafluoroethane from Industrial Vents. Presented at the Air & Waste Management 

Association 89th Annual Meeting, Nashville, TN, June 23-28. 

Hall, T.L. 1993. Dow Chemical SORBATHENE? Solvent Vapor Recovery Unit. Presented at 

American Chemical Society, Emerging Technologies in Hazardous Waste Management, Atlanta, 

GA, September 29, 1993. 

l l 

11 
P.79 

Chapter 4 

OSHA Regulations and Policies Affecting Worker Exposures in FRP/C and 

Boat Building Industries 

OSHA regulations governing the permissible exposure limit (PEL) for styrene and the 

ventilation system design in the FRP industry were summarized and presented in an RTI report 

(Kong et al., 1996)v That report also concluded that concentrating the exhaust air stream and 

reducing the exhaust flow would reduce the cost of control. However, the worker exposure is 

bounded by OSHA's PEL for styrene. The current 8-hour time-weighed-average (TWA) PEL for 

styrene is 100 ppm. The TWA short-term exposure limit (STEL) is 200 ppm for 15 minutes • 

during a work day and 600 ppm for 5 minutes in any 3 hours. 

John B. Jenks, the-Chairman of the Society of the Plastics Industry, Inc.'s Styrene 

Information & Research Center, and several industry officials sent a letter to Joseph A. Dear, the 

Assistant Secretary of Labor for OSHA, on January 29, 1996, and declared a willingness to 

voluntarily comply with lower exposure limits than those set by OSHA in its January 1989 rule 

on PEL for styrene and other air contaminants (OSHA, 1996). The lower limits are 50 ppm for 

an 8-hour TWA and 100 ppm for short-term exposure. The industry groups volunteering to 

lower exposure limits are the Society of the Plastics Industry, Inc.'s Composites Institute, 

Composites Fabricators Association, National Marine Manufacturers Association, and 

International Cast Polymer Association. These industry groups use polyester resins that emit 

styrene in the production processes. The goal is for these industry groups to comply with the 

lower exposure limits by July 1997. 

As the worker exposure limits are lowered, more efficient exhaust systems will be needed 

to remove the same amount of emissions or employees who may not presently be wearing 

respirators will need to wear them. General ventilation, also called dilution ventilation because it 

uses fresh air to achieve lower worker exposure levels, is not practical and would be expensive in 

the winter when makeup air is heated to maintain a constant temperature for product quality. 

Therefore, new air flow management practices to remove styrene emissions effectively or a 

respiratory protection program will be necessary to comply with lower exposure limits. 

This section presents (1) the summary and implication of OSHA regulations related to 

styrene emissions and ventilation in the FRP industry, (2) the explanation for "de minimis 

violations" under the OSHA policy, and (3) local air flow management practices and 

modifications to spray booths that could be considered for the ventilation and worker exposure 

issues. 

4.1 Summary and Implication of OSHA Regulations 

If a facility does not have a designated booth or area for gel coating and resin application 

in ah open molding process, the emissions from these operations will be dispersed in the work 

12 

1-2 
P.80 

area and the surrounding open space. Under these conditions, the worker exposures are limited 

to the styrene PELs listed in Table Z-2 in 29 CFR § 1910.1000 (OSHA, 1993) or as shown 

above. Title 29 CFR § 1910.1000 (e) states that administrative or engineering controls (e.g., 

enclosure or confinement of the operation, general and local ventilation, and substitution of less 

toxic materials) must first be determined and implemented whenever feasible. When such 

engineering controls are not feasible to achieve full compliance or while they are being instituted, 

protective equipment or any other protective measures should be used to keep the exposure of 

employees to air contaminants within the limits prescribed in the section. Whenever respirators 

are used, their use should comply with requirements in 29 CFR § 1910.134 "Respiratory 

Protection." 

When a facility uses a spray booth, its design must comply with regulations in 29 CFR § 

1910.94 (c) and § 1910.107. Section § 1910.94 (c) lists the design and construction of the spray 

booth and the minimum air flow velocities that must be designed and maintained at the entrance 

to the spray booth under various operating conditions in order to meet health and safety 

requirements. Section § 1910.107 is adopted by OSHA from National Fire Protection 

Association (NFPA) 33-1969 (NFPA, 1969) "Standard for Spray Finishing Using Flammable and 

Combustible Materials." The NFPA-33 standard is explicitly a fire and explosion safety 

standard. Therefore, the OSHA standard at 29 CFR § 1910.107 pertains to the prevention of 

workplace fire and explosion hazards and does not pertain to health considerations. 

Because the industry has volunteered to comply with lower PELs, facilities having 

difficulty meeting the lower limits will have to build spray booths for their styrene-emitting 

operation, apply air flow management to exhaust styrene emissions, or provide respirators for 

employees who could be exposed to styrene concentrations above the PELs. These facilities will 

choose one of these options based on the feasibility of using engineering controls, building spray 

booths, applying air flow management practices, changing material/equipment/process, or 

providing personal respirators. When the employee exposures are above the PELs, as determined 

by personal sampling, the employer can work with the OSHA compliance officer to determine a 

schedule for an interim abatement system (e.g., providing respirators to employees) and a long 

term abatement system (e.g., building a ventilation system). Feasibility of the abatement systems 

will be considered by the facility operator and the compliance officer in meeting the PELs. If 

worker exposures still can not meet PELs after engineering controls have been employed, then 

the respiratory program will become a permanent program (Smith, OSHA, personal 

communication, October 15, 1996). 

4.2 De Minimis Violations 

According to the OSHA policy (Shepich, 1990), de minimis violations are violations of 

standards that have no direct or immediate relationship to employee safety or health. Whenever 

de minimis conditions are found during an inspection, they are documented the same way as any 

other violation but are not included on the citation. De minimis violations result in no penalty 

and no required abatement. The criteria for finding a de minimis violation are as follows: 

13 

12> 
P.81 

An employer complies with the clear intent of the standard but deviates from its particular 

requirements in a manner that has no direct or immediate relationship to employee safety anc 

health. These deviations may involve distance specifications, construction materials 

requirements, use of incorrect color, minor variations from recordkeeping, testing, or 

inspection regulations, or the like. 

An employer complies with a proposed standard or amendment or a consensus standard 

rather than with the standard in effect at the time of the inspection when the employer's 

action provides equal or greater employee protection. 

An employer's workplace is at the "state of the art" that is technically beyond the requiremen 

of the applicable standard and provides equivalent or more effective employee safety or 

health protection. 

Under an OSHA policy for de minimis violatiops, employers are encouraged to abide by 

the standard applicable to their operations that provides equal or greater employee protection 

rather than with the OSHA standard in effect at the time of the inspection. 

4.3 Local Air Flow Management and Spray Booth Modifications 

The most effective way to reduce worker exposure is to directly remove styrene emission' 

from the source before the pollutants have a chance to disperse. Local air flow management, 

such as local extraction ventilation or a spray booth, removes emissions at the source and 

therefore reduces the amount of air to be exhausted and the amount of makeup air to be heated. 

Several local extraction ventilation systems are presented in the earlier report (Kong et al., 1996). 

These local extraction ventilation systems apply the push-pull ventilation principle in that fresh 

makeup air is admitted at one end of the work area and the air current picking up the emissions is 

exhausted at the other end of the work area. An operator can reduce unnecessary exposure by 

staying in the upwind side of the ventilated work area. 

As the EPA Office of Air Quality Planning and Standards (OAQPS) develops maximum 

achievable control technology (MACT) standards for the FRP industry, new facilities using 

greater than a certain quantity of resin and gel coat in an open molding process may be required 

to reduce their emissions. Emissions from concentrated sources in certain operations, such as 

continuous lamination, pultrusion, and SMC production, can be captured and exhausted using a 

vent hood. Emissions from other open molding processes, such as gel coating and resin sprayup, 

need to be confined in a spray booth that meet OSHA's requirements. A spray booth can be 

designed to meet the requirements of a total enclosure so that the emissions can be completely 

captured. In this case, fresh makeup air should be supplied to the operator's breathing zone in 

the spray booth. 

If the worker exposures are still higher than the PELs after proper engineering controls 

(i.e., confinement, local extraction, or general ventilation) have been implemented, then the 

operator should wear a respirator or a positive-pressure respirator with fresh uncontaminated air 

supply. The fresh air supplied to a positive-pressure respirator should meet certain air quality 

14 

lAr 
P.82 

requirements and if the air is supplied by an oil-based compressor there must be a CO alarm to 

detect CO in the air (Smith, OSHA, personal communication, October 15, 1996). 

It is common for the employers of some large FRP and boat building facilities to provide 

respirators to their employees for additional protection even though they may in compliance with 

the PELs. Positive-pressure respirator with full body protection and fresh air supply is not 

common in the FRP and boat building industries; however, such a system is used in an enclosed 

paint booth in Hatteras Yachts in New Bern, North Carolina. 

Modifications to spray booths, such as a split flow recirculation, have been examined in a 

large painting booth at a military installation (Hughes et al., 1994). A portion of the exhaust 

from the spray booth that contain less pollutants is recirculated to the front of the spray booth 

after mixing with fresh makeup air. The concentration in the jeturn air is less than the PELs. 

The balance of the exhaust, which is at a higher concentration, is vented to an add-on emission 

control device. The purpose of recirculation is to increase the outlet concentration and reduce the 

exhaust flow so that the capital and operating costs of the add-on control can be minimized. The 

recirculating air can be returned to the-spray booth at any point, either mixed with fresh makeup 

air or not mixed with fresh makeup air. In the laner case, the fresh makeup air can be supplied to 

the breathing zone of the operator to provide the most protection. Although recirculation in the 

spray booth is not recommended by OSHA, the bottom line is that worker exposures should not 

exceed the PELs (R. Fairfax, Health Compliance Program, Occupational Safety and Health 

Administration, personal communication, September 9, 1996). 

If all forms of air flow management are not feasible, a facility should consider 

preconcentrating the exhaust stream to reduce the flow rate and to increase the concentration of 

the exhaust stream for an add-on control. Preconcentration reduces not only the capital cost but 

also the operating cost of the add-on control; it also reduces natural gas usage and generates 

fewer secondary pollutants than straight thermal oxidation of the entire exhaust stream. An 

analysis of secondary pollution and natural gas usage for various control options is presented in 

Chapter 5. 

References 

Hughes, S., J. Aver, and R. Sutay. 1994. Demonstration of Split-Flow Ventilation and 

Recirculation as Flow-Reduction Methods in an Air Force Paint Spray Booth, AL/EQ-TR-1993-

0002, Armstrong Laboratory, Environics Directorate, Tyndall AFB, FL. 

Kong, E.J., M.A. Bahner, and S.L. Turner. September 1996. Assessment of Styrene Emission 

Controls for FRP/C and Boat Building Industries. EPA-600/R-96-109 (NTIS PB97-104640), 

Research Triangle Park, NC. 

National Fire Protection Association (NFPA). 1969. Standard for Spray Finishing Using 

Eammable and Combustible Materials, NFPA 33. Quincy, MA. 

15 

i£> 
P.83 

OSHA (Occupational Safety and Health Administration). 1993. Occupational Safety and Heal 

Standards. 29 CFR 1910. Code of Federal Regulations. Washington, DC: Office of the Feder 

Register, July 1. 

OSHA (Occupational Safety and Health Administration). 1996. OSHA Announces that Styren 

Industry has Adopted Voluntary Compliance Program to Improve Worker Protection. News 

Release USDL:96-77, March 1. 

Shepich, TJ. 1990. Directorate of Compliance Programs, Occupational Safety and Health 

Administration. Letter to S.R. Wyatt, Emission Standards Division, U.S. Environmental 

Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park, NC, 

January 16. 

16 

\U 
P.84 

Chapter 5 

Assumptions in the Society of Plastics Industry/Composites Institute's 

(SPI/CI) Study on Noneconomic Impacts of Incineration Controls 

Energy use and generation of secondary pollution for control devices are dependent on 

the type of control device selected and the flow rate into the control device. The SPI/CI Study on 

Non-Economic Impacts of Incineration Controls (Haberlein, 1996) was based on thermal 

oxidation of a 30,000 ft'/min exhaust stream containing 20 ppm of styrene. The following 

sections discuss the assumptions of a thermal oxidizer operating on a stream containing 20 ppm 

of styrene. Appendix A contains a discussion of other assumptions in the SPI/CI study. 

5.1 Use of Thermal Oxidizer 

The SPI/CI study assumes a thermal oxidizer operating on a stream containing 20 ppm of 

styrene. However, previous RTI analyses of the costs of controls has indicated that preconcentration/oxidation systems have lower annualized costs than straight thermal oxidation for 

control device inlet concentrations below approximately 300 ppm. For example, Figure 5-1 

shows RTI-calculated control costs for diermal oxidation, catalytic oxidation, and three preconcentration/oxidation systems, for a plant with uncontrolled emissions of 400 ton/yr (operating 

4,000 h/yr).1 Figure 5-1 shows that the three preconcentration/oxidation technologies (MIAB, 

Polyad, and Durr rotary concentrator systems) have lower total costs per unit of styrene removed 

than straight thermal oxidation or catalytic oxidation. Therefore, it is likely that an FRP 

company would choose a preconcentration/oxidation system over straight thermal oxidation for 

an exhaust stream containing 20 ppm styrene based on lower total annualized cost. It is also 

likely that an FRP company would attempt to increase the styrene concentration (i.e., lower the 

flow rate), compared to the 20-ppm assumption in the SPI/CI study. This point is discussed in 

the following section. *o 

5.2 Control Device Inlet Concentration of 20 ppm 

Noneconomic impact analyses in the SPI/CI study are based on an assumed styrene 

concentration of 20 ppm to a thermal oxidizer. To evaluate this assumption, RTI reviewed the 

following: (1) economic incentives for maximizing inlet concentrations (minimizing flow rates) 

to end-of-pipe controls, (2) plant-wide average exhaust concentrations currently found at FRP 

plants, (3) recent and possible future changes to allowable exposure levels for employees of FRP 

plants, (4) existing relationships between employee exposures to styrene and exhaust 

concentrations at FRP plants, and (5) possible methods for new plants to increase concentrations 

(decrease flow rates) to controls while maintaining or lowering employee exposures. 

1

 Figure 5-1 is based on a cost curve presented in a previous EPA report (Kong et al., 1996), with 

corrections as discussed in Appendix B to this report. 

17 

A 
Table 5-1. Styrene Exhaust Concentrations at Existing Open Molding Plants with Resin/Gel Coat Usage Greater (ban 1,000 tons/yr 

03 

PLANT NAME 

AQUA GLASS 

ARE. , INC. 

LASCO BATHWARE 

UNIVERSAL RUNDLE 

AMERICAN STANDARD 

ARE. , INC. 

MILLENIUM PRODUCTS 

AQUA GLASS 

Arithmetic mean 

Median 

CITY 

KLAMATH FALLS 

MASILLON 

MOA PA 

OTTUMWA 

SALEM 

MOUNT EATON 

ELKHART 

ADAMSVILLE 

ST 

OR 

OH 

NV 

IA 

OH 

OH 

IN 

TN 

UNCONTROLLED 

EMISSIONS (lon/yr) 

1.175 

770 

739 

328 

53 

108 

123 

1,151 

OPERATING 

HOURS (h/yr) 

6,000 

,7,488 

4,290 

4.160 

2,500 

3,120 

2,000 

6,000 

PLANT-WIDE 

FLOW RATE 

(fl3/iniii) 

97,000 

55,000 

155,400 

110,700 

35,000 

70,000 

125,000 

390,000 

AVERAGE 

STYRENE 

CONCENTRATION 

(ppm) 

249 

231 

137 

88 

75 

61 

61 

61 

120 

82 

O 

oo 
P.86 

5.2.3 Recent and Potential Future Changes in Allowable Exposures to Styrene 

Currentiy, OSHA PELs for styrene are 100 ppm as an 8-hour time-weighted-average 

(TWA) and 200 ppm as a 15-minute short-term-exposure-limit (STEL). The SPI/CI study notes 

that the reinforced plastics industry has voluntarily agreed to meet a 50-ppm TWA and a 100-

ppm STEL. Compliance with the agreement will go into effect in July 1997. The SPI/CI study 

further notes that the American Council of Government Industrial Hygienists (ACGIH) has 

placed styrene on the Notice of Intended Change list to lower the styrene threshold limit value 

(TLV) to 20 ppm, with a STEL of 40 ppm. 

The SPI/CI study uses a control device inlet concentration of 20 ppm. This is equal to the 

TLV being proposed by the ACGIH. RTI has no information to indicate that OSHA currently 

plans to lower the TWA to 20 ppm. 

5.2.4 Existing Relationships Between Worker Exposure and Exhaust Concentration 

Even if the OSHA TWA were lowered to 20 ppm, it would be reasonable to assume that a 

company building a new facility would have an average exhaust concentration to an end-of-pipe 

control that would be above 20 ppm. One reason for this is the strong economic incentive to 

maximize concentration (minimize flow rate), as discussed in Section 6.1. Another reason for 

this is that most capture systems would logically be oriented to draw styrene away from the 

worker, rather than drawing styrene into the worker's breathing zone. This concept is illustrated 

in Figure 5-2. 

'o1-

Currently, there is little available data relating average exhaust concentrations to worker 

exposures. Some data are available from the Lasco-South Boston (Virginia) tub-and-shower 

facility, and are presented in Table 5-2. Table 5-2 indicates that gel coat gun operators and 

lamination rollers had the highest average worker exposures during the measurement period and 

that the average ratio of exhaust-duct-concentration-to-worker-exposure was 2.36 and 2.42, 

respectively. 

RTI is analyzing data collected at a tub-and-shower facility in which employee exposure 

and exhaust duct concentration were measured simultaneously. The results of this testing are 

expected to be published by February 1997 (see Section 5.2.5). 

5.2.5 Potential Methods to Increase Concentration to Downstream Controls 

Previous research by RTI identified several potential methods to decrease required flow 

rates for end-of-pipe controls while preventing excess employee exposure levels. These methods 

included: (1) local air flow management, (2) spray booth modifications (such as split-flow spray 

booths and spray booth recirculation), and (3) enclosures and total enclosures. 

RTI is currently analyzing data from proof-of-concept testing at a tub-and-shower facility. 

This testing is evaluating the ability of spray enclosures and air flow management techniques to 

increase exhaust duct concentration while 

21 

!<? 
Main Filter Bank 

Main Exhaust to Atmosphere 

(high volume, low concentration) 

Fresh Air Supply 

N 0 

tf 

Figure 5-2. Typical open molding operation in a spray booth. 
P.88 

Table 5-2. Comparison of Average Styrene Exhaust Concentration (290 ppm) (Strum, 

1995) With Worker Exposure Levels (Boyd, 1995) at Lasco Bathware, South Boston, VA 

Job Category 

1. Gel Coat Gun Operator 

2. Lamination Gun Operator 

3. Lamination Roller 

4. Barrier Coat 

Gun Operator 

5. Part Puller 

6. QC Technician 

7. Mixer 

8. Trimmer 

9. Waxer 

Number of 

Measurements* 

5 

17 

6 

5 

2 

'4 

5 

"l 

1 

Exposure 

Range* 

(ppm) 

88-199 

37-267 

92-142 

61-105 

32-39 

23-75 

15-44 

Average 

Exposure* 

(ppm) 

123.0 

90.4 

120.0 

t 19A 

35.3 

37.0 

31.6 

,46.0 

25.0 

Average Ratio, 

Exhaust/Exposure 

2.36 

3.21 

2.42 

3.65 

8.22 

7.84 

9.18 

6.30 

11.60 

Data provided to Madeleine Strum by Daniel Boyd (Boyd, 1995). 

maintaining or lowering worker exposures. The enclosure concept involves placing a part inside 

an enclosure while the spray gun operator stands outside the enclosure. The air flow 

management techniques involve the use of a close-capture exhaust panel. In this testing, one 

flame ionization detector (FID) device continuously measured exhaust duct concentration while 

another (portable) FID was used to continuously monitor worker exposure. In this manner, the 

ratio of exhaust duct concentration to worker exposure concentration could be continuously 

monitored and compared with "baseline" results from an unmodified spray booth. The results of 

the RTI enclosures/air flow management testing are expected to be available by February 1997. 

5.2.6 Conclusions on Assumption of Control Device Inlet Concentration of 20 ppm 

There are strong economic incentives for a company to maximize the concentration 

(minimize the flow rate) to a control device. Most existing facilities with open-mold spraying 

(even those without controls) currently have exhaust concentrations well above 20 ppm. 

Lowering allowable worker exposure levels can force lower concentrations to a control device. 

However, it appears likely that, even for worker exposure levels of 20 ppm, minimum exhaust 

concentrations on the order of 50-100 ppm could be achieved with current, or slightly improved, 

air flow management practices. Therefore, the assumption of a control device inlet concentration 

of 20 ppm appears to be too low. 

23 

Z l 
P.89 

r i 

References 

Boyd, D., Daniel P. Boyd & Company, 1995. Presentation for the U.S. Environmental Protection 

Agency's site visit at Lasco Bathware - South Boston (VA), June 22. 

Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced 

Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, MI. 

Strum, M., U.S. Environmental Protection Agency, 1995. Site Visit Report - LASCO Bathware, 

South Boston, VA. 

24 

Z2-
Chapter 6 

RTI Analysis of Noneconomic Impacts of Controls 

RTFs analysis of noneconomic impacts of controls includes the development of 

normalized curves to predict noneconomic impacts. Noneconomic impacts are also calculated 

for a specific, typical existing facility that has gel coat and sprayup processes. 

6.1 Normalized Curves for Natural Gas Usage and Secondary Pollutant Emissions 

To compare energy usage and secondary pollutant emissions for various flow rates and 

styrene mass emission rates, we must "normalize" the data. Data- presented in Section 6.1 have 

been "normalized" to reflect fuel usage and secondary pollutant emissions per ton of styrene 

removed (based on 95 percent removal efficiency). 

4f 

Most of the figures in this section include the following control options: (1) a thermal 

oxidizer, with 95 percent heat recovery, operating at 1,800 °F (as assumed in the SPI/CI study); 

(2) a thermal oxidizer, with 95 percent heat recovery, operating at 1,500 °F (which could produce 

a styrene destruction efficiency of 95 percent); (3) a catalytic oxidizer, with 95 percent heat 

recovery, operating at 650 °F (which could produce a styrene destruction efficiency of 

95 percent); and (4) a preconcentrator/catalytic oxidizer, based on the Polyad system, that has a 

natural gas requirement of 96,000 Btu/h at 30,000 ftVmin. (The Polyad system requires 

96,000 Btu/h to desorb styrene, for a system with an inlet flow of 30,000 ftVmin.) 

The figures in this section can be used in the following manner: In Figure 6-1, the natural 

gas usage for a thermal oxidizer operating at 1,800°F, with an inlet concentration of 20 ppm, is 

approximately 650,000 ft3 per ton of styrene removed. Therefore, if a thermal oxidizer removed 

100 tons of styrene under these conditions, the natural gas usage would be 65 million cubic feet. 

Similarly, from Figure 6-1, the natural gas usage for a preconcentrator/oxidizer operating with a 

styrene inlet concentration of 100 ppm is approximately 4,200 ftVton of styrene removed. 

Therefore, if a preconcentrator/oxidizer removed 100 tons of styrene under these conditions, the 

natural gas usage would be 420,000,ft3. 

6.1.1 Natural Gas Usage 

Figure 6-1 presents normalized curves for natural gas usage for various control options. 

Figure 6-1 also contains normalized curves for the sensible heat required to raise an exhaust 

stream from average outdoor temperatures to an indoor temperature of 75 °F for two locations 

(i.e., Fort Wayne, Indiana, and Los Angeles, California). The curves for sensible heating 

requirements are included to compare the additional natural gas usage for controls with existing 

natural gas for heating. 

•»• 

In Figure 6-1, the top left point of the four control-option curves represents the 

assumptions in the SPI/CI study (i.e., a thermal oxidizer, with 95 percent heat recovery, operating' 

25 

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Styrene Intel concentration (ppm) 

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Figure 6-1. Normalized natural gas usage for various control 

options and for sensible heating of exhaust stream. 

t 
P.92 

at 1,800 °F, with an inlet concentration of 20 ppm). The natural gas requirement for this point is 

approximately 650,000 ftVton of styrene removed. In contrast, for a preconcentrator-catalytic 

oxidizer operating at 88 ppm, the natural gas requirement is approximately 5,000 ftVton of 

styrene removed. 

Figure 6-1 illustrates that the natural gas usage for a preconcentrator/catalytic oxidizer is 

actually less than the sensible heat required to heat an equal flow rate to 75 °F, in Fort Wayne, 

Indiana, or Los Angeles, California. 

6.1.2 Carbon Dioxide Emissions 

Figure 6-2 presents normalized carbon dioxide emissions for four control-option curves. 

In Figure 6-2, the top left point of the four curves represents the Assumptions in the SPI/CI study 

(i.e., a thermal oxidizer, with 95 percent heat recovery, operating at 1,800 °F, with an inlet 

concentration of 20 ppm). The carbon dioxide generated by natural gas combustion for this point 

is approximately 41 ton/ton of styrene removed. In contrast, for a preconcentrator-catalytic 

oxidizer operating at 88 ppm, the carbon dioxide generated by natural gas combustion is 

approximately 0.33 ton/ton of styrene removed. 

All of the curves in Figure 6-2 depict only die carbon dioxide emissions generated by 

burning natural gas to destroy styrene. These curves do not include the carbon dioxide created 

naturally by the degradation of styrene. Chemical stoichiometry dictates that every ton of styrene 

converts to 3.38 tons of carbon dioxide. 

6.1.3 Nitrogen Oxide Emissions 

The SPI/CI study assumed 15 ppm of nitrogen oxides (NOJ are emitted from the thermal 

oxidizer. This was based on the following numerical values, as reported by Haberlein 

(Haberlein, 1996): 

• 50-100 ppm, as reported by CVM 

• 10-15 ppm, as reported by Wheelabrator 

• 13 ppm, as reported by Tellkamp 

• <10 ppm, as reported by Huntington. 

RTFs research appears to indicate that values of less than 10 ppm are probably more 

typical for thermal oxidizers, particularly if the oxidizer operates at approximately 1,500 °F, and 

especially if the oxidizer uses technology to reduce NOx emissions, such as low-NOx burners. 

Specifically, RTI's research indicates the following ig: 

Smith Engineering stated that none of the 25 installations for which they have 

NOx measurements has an average concentration over 10 ppm. 

Durr Industries provided NOx emissions test data for two installations. Both 

installations had average NOx emissions less than 10 ppm. The time-weighted 

27 

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• Existing plants 

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20 40 60 80 100 120 140 160 

Styrene Inlet concentration (ppm) 

180 200 220 240 260 

Figure 6-2. Normalized additionar carbon dioxide generated by natural gas combustion for 

various control options. 

* "Additional" means that the values do not include the 3.38 Ions of CO, generated by Ihe conversion of styrene (C8H8) to CO, (i.e., every mole of styrene 

[MW=104J generates 8 moles of carbon dioxide [MW=44j). 

eo 
P.94 

average N0X generation for a thermal oxidizer installed in an automotive 

application was 2.7 ppm (Gupta, 1996). 

• Process Combustion Corporation published a paper that concluded, "Various NOx 

combustion control techniques are available. With waste gases free of nitrogenbound compounds, NOx emissions from thermal oxidation can be reduced to less 

than 10 ppm." (Nutcher and Lewandowski, 1994) 

• The Institute of Clean Air Companies noted that operation of a thermal oxidizer 

should result in less than 10 ppm of NOx (Wax, 1995). 

Fewer data are available for NOx emissions from catalytic oxidizers. RTI investigation of 

this subject yielded the following: • * 

• Englehard Process Emission Systems (South Lyon, Michigan) published a paper 

that concluded that a catalytic oxidizer produces 0 to 2 ppm of NOx contribution 

(Gribbon, 1996). 

• The Institute of Clean Air Companies noted that catalytic oxidizers run at much 

lower temperatures than thermal oxidizers (and should therefore produce less 

NOx). 

Figure 6-3 shows normalized NOx emission curves for various control technologies. 

There are actually three NOx curves for thermal oxidation, based on three different assumptions 

for NOx outlet concentration. The top curve represents an assumption of 15-ppm outlet NOx, as 

assumed in the SPI/CI study. The middle thermal-oxidation curve represents an assumption of 

8.8-ppm outlet NOx, as quoted from Smith Engineering. The bottom thermal-oxidation curve 

represents an assumption of 2.7-ppm outlet NOx, as measured in the May 1995 testing by Durr 

(Gupta, 1996). 

6.2 Calculations for Specific Plant 

Bar graphs depicting energyiise and secondary pollutant emissions are presented for a 

specific plant: the Universal Rundle plant in Ottumwa, Iowa. This plant has calculated 

characteristics as shown in Table 6-1. 

The Universal Rundle plant in Ottumwa, Iowa, has a calculated uncontrolled styrene 

exhaust concentration of 88 ppm, and a flow rate of 110,700 ftVmin. For each bar graph, there is 

one bar representing a concentration of 20 ppm and a flow rate of 487,080 ftVmin. This 487,080 

ftVmin flow rate represents the flow rate that would occur if emissions were diluted from the 

actual value of 88 ppm to the hypothetical value of 20 ppm assumed in the SPI/CI study. 

29 

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• Existing plants 

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Inlet styrene concentration (ppm) 

180 200 220 240 260 

Figure 6-3. Normalized NO, emissions for various control options. 

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P.96 

Table 6-1. Characteristics for Specific Plant (Universal Rundle, in Ottumwa, Iowa) 

Characteristic 

Uncontrolled styrene emissions 

Assumed control efficiency 

Control device inlet concentration 

Air flow rate into control device 

Operational schedule 

Value 

328 ton/yr 

95 percent (i.e., 312 ton/yr of styrene 

removed, and resulting controlled emissions 

of 16 ton/yr). 

88 ppm 

110,700 ftVmin 

4,160 h/yr ' 

6.2.1 Natural Gas Usage 

Figure 6-4 compares natural gas usage for several control options and for sensible heating 

for the specific plant. The bar on the left side of the page represents the natural gas that would be 

used if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in the 

SPI/CI study. All other bars represent the actual plant flow rate of 110,700 ftVmin. 

Figure 6-4 indicates that the natural gas used in annual heating for an exhaust flow of 

110,700 ftVmin is approximately 3.6 million ftVyr (based on heating requirements in Fort 

Wayne, Indiana). In contrast, the natural gas requirement for the preconcentrator/catalytic 

oxidizer option (which is based on the Polyad system), is approximately 1.5 million ftVyr. It 

should be noted that the calculated value of 3.6 million ftVyr for sensible heating of the exhaust 

stream does not reflect all the heating requirements for an FRP facility. Additional heating 

would be required to replace heat losses through the walls and ceiling of the facility. Natural gas 

might also be used for latent heating, if humidification is required during the winter. 

The calculations for natural gas usage in Figure 6-4 can be compared with total natural 

gas usage in the United States in 1995. The total natural gas usage in the United States in 1995 

was approximately 2.2 x 1013 ft3, which is approximately a factor of 100,000 times greater than 

the natural gas usage of the highest option shown in Figure 6-4. 

6.2.2 Carbon Dioxide Emissions 

Figure 6-5 presents carbon dioxide emissions for several control options for the specific 

plant. The bar on the left side of the page represents the carbon dioxide that would be produced 

if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in the 

SPI/CI study. All other bars represent the actual plant flow rate of 110,700 ftVmin. 

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-

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110.700 cfm 

* 

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Catalytic Concentrator 

(650 oF), 88 + Catalytic. 

ppm sty 88 ppm sty 

110.700 cfm 110.700 cfm 

Figure 6-4. Natural gas usage for various control options and for sensible heating at a typical 

plant (basis: 328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr) 

sly = inlet styrene concentralion 

T l 

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(1800 oF). 

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487,080 cfm 

Thermal 

(1800 oF). 

88 ppm sty 

110,070 cfm 

Thermal 

(1.500 oF), 

88 ppm sty 

110.700 cfm 

Catalytic 

(650 oF), 88 

ppm sty 

110.700 elm 

Concentrator 

-f Catalytic. 

88 ppm sty 

110,700 cfm 

Figure 6-5. Carbon dioxide emissions for various control options at a typical plant (basis: 

328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr). 

sty = inlet styrene concentration C02bar Chart 1 

T l 

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P.99 

Each bar in Figure 6-5 has three components: 1) the C02 produced by natural gas used in 

oxidation, 2) the C02 that would be produced by burning natural gas to heat the flow stream from 

the average outdoor temperature to 75 °F, and 3) the CO, produced from the stoichiometric 

degredation of styrene to C02 (and water). 

The bar on the left side of the figure represents the CO, that would be produced assuming 

straight thermal oxidation of a 20 ppm flow stream. In order to reduce the concentration from 

the actual value of 88 ppm, it would be necessary to increase the exhaust flow from the actual 

value of 110,700 ftVmin to a hypothetical value of 487,080 ftVmin. The total CO, produced in 

this hypothetical situation would be over 14,000 tons/yr, of which approximately 12,000 tons/yr 

would be due to natural gas used for oxidation. 

Other bars in Figure 6-5 reflect the actual exhaust conditions for the plant 

(110,700 ftVmin at 88 ppm). The bar on the far right presents the C02 emissions from a 

preconcentrator/catalytic oxidizer. A preconcentrator/oxidizer is the control that would be most 

likely to be selected for a flow stream of 110,700 ftVmin at 88 ppm, due to the fact that the 

preconcentrator/oxidizer has a lower total annualized cost than the other options. For a 

preconcentrator/oxidizer, the total C02 emissions are approximately 1,400 tons/yr. The vast 

majority of these emissions (over 1,100 tons/yr) are due to the stoichiometric degredation of 

styrene to C02. Only 90 tons/yr of CO, emissions are due to combustion of natural gas used in 

heating the air for desorption. 

6.23 Nitrogen Oxide Emissions 

Figure 6-6 presents NOx emissions (as NO^ for several control options for the specific 

plant. The bar on the left side of the page represents the NOx emissions that would be produced 

if the flow rate were raised to 487,080 ftVmin, producing the 20-ppm value assumed in SPI/CI 

study. All other bars represent the actual plant flow rate of 110,700 ftVmin. 

The bar on the right, which is barely visible, indicates NOx emissions for a 

preconcentration/catalytic oxidation system. A preconcentration/oxidation system would be the 

most likely control choice for a flow rate of 110,700 ftVmin, containing 88 ppm styrene, due to 

lower total annualized cost. The-NO, emissions for this control option at this facility would be 

0.09 tons/yr. This can be contrasted with the estimated styrene removal of 312 tons/yr. 

6.2.4 Radon Emissions 

Figure 6-7 presents radon emissions from natural gas combustion for several control 

options for the specific plant. The bar on the left side of the page represents the radon emissions 

that would be produced if die flow rate were raised to 487,080 ftVmin, producing the 20 ppm 

value assumed in the SPI/CI study. All other bars represent the actual plant flow rate of 110,700 

ftVmin. 

34 

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120 

100 

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Btn 

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Thermal 

(1800 oF), 

20 ppm sly 

487.080 elm 

Thermal 

(1800 oF), 

88 ppm sty 

110,070 cfm 

Thermal 

(1.500 oF). 

88 ppm sty 

110,700 cfm 

Catalytic 

(650 oF), 88 

ppm sty 

110,700 cfm 

Concentrator 

+ Catalytic, 

88 ppm sty 

110,700 cfm 

Figure 6-6. NOx emissions for various control options at a typical plant (basis: 328 ton/yr 

uncontrolled styrene emissions and 4,160 operating h/yr) 

} 
120.000 

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Thermal 

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88 ppm sty 

110,070 cfm 

Thermal 

(1,500 oF), 

88 ppm sty 

110,700 cfm 

Catalytic 

(650 oF). 88 

ppm sty 

110,700 cfm 

Concentrator 

+ Catalytic, 

88 ppm sty 

110,700 cfm 

Figure 6-7. Radon emissions due to natural gas combustion for various control options at a 

typical plant (basis: 328 ton/yr uncontrolled styrene emissions and 4,160 operating h/yr). 

sty = inlet styrene concentration RarWili.-jr (*.*•-.. I TJ 
P.3 

The radon emission calculations in Figure 6-7 are based on an average radon content of 

20 pCi/L in natural gas as assumed in the SPI/CI study. This value was also used in a study of 

radionuclide emissions from natural-gas fired steam-electric generating plants (Nelson, 1995). 

According to the Institute for Clean Air Companies, the Institute for Gas Technology reports 

radon levels typically less than 1 pCi/L (Wax, 1996). 

6.3 Conclusions 

Calculations of noneconomic impacts in the SPI/CI study were based on an exhaust 

stream containing 20 ppm of styrene, directed to a thermal oxidizer. However, for economic 

reasons, it would be unlikely that a new plant would be designed with a 20-ppm exhaust stream 

directed to an end-of-pipe control device. And, if a new plant were designed with a 20-ppm 

exhaust stream directed to a control device, a preconcentration/oxidation system would probably 

be chosen over straight thermal oxidation, again for economic reasons. 

• 

Natural gas usage and secondary pollutant emissions were found to be considerably less 

for preconcentration/oxidation systems than' for thermal oxidation, in me range from 0 to 

approximately 300 ppm of styrene. Since preconcentration/oxidation systems appear to have 

lower annualized costs than straight thermal oxidation in this range, the choice of 

preconcentration/oxidation systems in this range lowers both economic and noneconomic 

impacts. 

References 

Gribbon, S. T. 1996. Englehard Process Emission Systems; "Regenerative Catalytic 

Oxidation," Presented at the 1996 Air & Waste Management Association Specialty Conference 

"Emerging Solutions to VOC and Air Toxics Control," Clearwater, FL. 

Gupta, A., Durr Industries, Inc., A facsimile on RTO JPerformance and NOx to Madeleine Strum, 

U.S. Environmental Protection Agency, August 6, 1996. 

Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced 

Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, MI. 

i 

Nelson, C, Estimates of Health Risks Associated with Radionuclide Emissions from FossilFueled Steam-Electric Generating Plants, EPA-402/R-95-16 (NTIS PB96-139753), August 1995. 

Nutcher, P. B. and D. A. Lewandowsi. 1994. Process Combustion Corporation; "Maximum 

Achievable Control Technology (MACT) for NOx Emissions from VOC Thermal Oxidation," 

AWMA paper number 94-WA74A.03, in Proceedings for the Air and Waste Management 

Association 87th Annual Meeting and Exhibition, Cincinnati, OH. 

Wax, M., Institute of Clean Air Companies, memorandum to Madeleine Strum, U.S. 

Environmental Protection Agency, August 11, 1995, Subject: Reinforced Plastic Composites. 

37 

2& 
P.4 

Wax, M., Institute of Clean Air Companies, memorandum to Mark Bahner, Research Trianri 

Institute, October 15, 1996, Subject: Radon Concentration in v.n.«i «... " ang J Subject: Radon Concentration in Natural Gas. 

38 

•*k 
P.5 

Appendix A 

Comments on Individual Statements in the SPI/CI Study 

39 

£3 
-Ei-i 

Appendix A 

Comments on Individual Statements in the SPI/CI Study (Haberlein, 1996) 

1) The (catalytic oxidizer) bed temperature is maintained at about 600 °C (1,100 °F) during 

normal operation. (Page IH-2). 

A more typical temperature range for catalytic oxidation of styrene is 600-700 °F (Patkar 

etal., 1994). 

2) The problem (of catalyst poisoning in a catalytic oxidizer) is severe and unpredictable... 

(Page m-2). 

A July 19, 1996 memorandum from Michael Wax (Institute of Clean Air Companies) to 

Madeleine Strum (EPA-OAQPS) states that catalyst plugging, poisoning, and 

deactivation are well understood, and may be ameliorated through appropriate system 

design and operating practices. He refers to an article in the September 1994 issue of 

Chemical Engineering, "Extend the Life of Pollution Control Catalysts," that discusses 

in-situ catalyst rejuvenation as an alternative to catalyst replacement. 

3) A thermal regenerative incinerator was selected for the hypothetical plant 

(30,000 ft3/min, 20 ppm styrene, 8,760 h/yr, 43 tons uncontrolled styrene emissions) 

because this type of incinerator has been shown to be the most cost-effective type of 

control compared to the recuperative or catalytic (recuperative) types. (Page m-3). 

This analysis ignores the option of preconcentration/oxidation, which appears to have a 

lower total annualized cost than any of these options (including regenerative thermal 

oxidation), for the hypothetical inlet conditions. 

4) For the hypothetical incinerator discussed above...at an oxidation temperature of 

1800 °F... (Page JR-5). 

A thermal oxidation temperature of 1,800 T is compatible with Haberlein's assumed 

styrene destruction efficiency of 99 percent. A lower thermal oxidation temperature, such 

as 1,500 °F, would be compatible with a lower destruction efficiency, such as 95 percent. 

5) The supplemental fuel requirement for an incinerator (with 95 percent heat recovery) 

operating at an exhaust flow rate of 30,000 cfm at 20 ppm VOC (and 1,800 °F) is 

3,310,000 Btu/h. (Page EU-5). 

The RTI cost spreadsheet for a thermal oxidizer under these conditions produces a 

calculated supplemental fuel requirement of 2,984,000 Btu/h, or approximately 

10 percent less. This represents fairly close agreement. 

•40 

38 
P.7 

6) Annual electrical consumption (for the hypothetical thermal oxidizer) is 1,230,000 kWh 

(over 8,760hours). (Page ffi-6). 

This represents power usage of 140 kW/h. The RTI cost spreadsheet for a thermal 

oxidizer (with 95 percent heat recovery) under these conditions is 125 kW/h, or 

approximately 10 percent less. This represents fairly close agreement. RTI's calculation 

was based on quotations from Salem Englehard (Mack, 1996). 

7) Unfortunately, these compounds (catalyzed resin aerosols and polystyrene-forming 

agents) are indeed present in the exhaust streams at most plants, as evidenced by the 

solid plastic residue that coats the inner surface ofthe ductwork in many locations. 

Further, no effective means of removing all of these airborne compounds is presently 

known. (Page ffi-13). ' 

Catalyzed resin aerosols are present in many plants, due to spraying operations. These 

resin aerosols are actually quite large, and are therefore easily removed by even coarse 

filtration. For example, RTI mass-balance testing conducted in June 1995 indicated 

approximately 99 percent panicle collection by a thin fiberglass veil. It could be expected 

that the fiberglass filter pads used at most plants would have an even higher collection 

efficiency. RTI has observed that casual fiberglass filter pad installation at many plants 

allows gaps or holes in the filter banks. This practice can dramatically lower collection 

efficiency, and would need to be avoided. Styrene gas (which can form polystyrene) is 

indeed present, and cannot Be removed by physical filtration. However, Durr Industries 

reports having rotary concentrator systems in Japan that have been running for over 10 

years without styrene polymerization. 

8) The report (on Polyad) shows an annual 10% Bonopore (adsorbent) loss out ofthe 

system's cyclone separator. (Page EI-14) 

Weatherly, Inc. (manufacturers of Polyad), in a July 18, 1996, memorandum to Madeleine 

Strum (EPA-OAQPS), indicated that they now guarantee annual Bonopore loss of 

5 percent or less. 

9) The calculated energy requirements for a 30,000 scfm Polyad concentrator system are • 

130 kW, and 96,000 Btu/hr. (Page ffi-15). 

Weatherly, Inc. (manufacturers of Polyad), in a 1996 memorandum to Madeleine Strum 

(EPA-OAQPS), indicated that the electrical requirement would actually be 62 kW, but 

the natural gas usage value was correct. 

References 

Haberlein, R.A. 1996. The Non-Economic Impacts of Incineration Controls for the Reinforced 

Plastics Industry. Prepared for SPI/Composites Institute, Ann Arbor, ML 

41 

&°. 
P.8 

Mack, S., Englehard Corporation, A facsimile on RCO Costs to Mark Bahner, Research Triangle 

Institute, Febmary 8, 1996. 

Patkar, A.N., J.M. Reinhold, and G. Henderson. 1994. "Demonstration of Capture and Control 

Efficiency for a Styrene Emission Source," Paper number 94-RAl 11.03, in Proceedings for the 

Air and Waste Management Association 87th Annual Meeting and Exhibition, Cincinnati, OH. 

42 

4C 
P.9 

Appendix B 

Revision ofthe Styrene Control Cost Spreadsheet Model and Cost Figures 

43 

4-\ 
RESEARCH TRIANGLE INSTITUTE _Rj 

Center for Environmental Analysis 

MFMORAiVDIIM 

DATE: October 9, 1996 

TO: Norman Kaplan, EPA/APPCD/MD-04 

Madeleine Strum, EPA/OAQPS/MD-13 

cc: Emery Kong (541-5964) 

FROM: Mark Bahner (541-6016) /Af.5 

SUBJECT: Errors in Styrene Control Cost Spreadsheets and Cost Figures. 

Contract 68-D1-0118 (Option IV), work assignment 156. (RTI project 6173-156). 

Contract 68-D1-0118 (Option V), work assignment 192. (RTI project 6684-192). 

As a result of activities conducted to prepare an Addendum to the report, "Assessment of 

Styrene Controls for FRP/C and Boat Building Industries" (EPA-600/R-96-109), I have discovered 

errors in the styrene control cost spreadsheets and in cost curves presented in the report. I do not 

believe that these errors significantly affect the accuracy of the spreadsheet total annualized cost 

calculations, or alter conclusions of the report. Therefore, per a telephone conversation with 

Norman Kaplan today, RTI will not attempt to revise the affected portions of EPA-600/R-96-109. 

The errors in fhe cost spreadsheets are as follows: 

1) Polyad System - The cost spreadsheet for the Polyad system was based on electrical 

usage of 22 kW at 5,000 cfm, and 59 kW at 15,000 cfm. Weatherly, Incorporated (manufacturer of 

Polyad) informed me in December 1995 that actual values would be 12 kW at 5,000 cfm and 32 

kW at 15,000 cfm. However, I neglected to change the spreadsheet accordingly. Additionally, the 

Polyad cost spreadsheet has a fuel usage of "zero" for all conditions. This was a simplifying 

assumption: a more accurate representation would be 48,000 Btu/hr at 15,000 cfm. 

These two errors actually tend to bias the total cost calculations in different directions, and 

therefore nearly cancel each other out, in terms of final cost. The incorrect and corrected values for 

a range of concentrations, and input mass rates (in tons per year) are shown in Table 1. 

3040 Cornvva:! S .=io = c • PCS- C":C£ =cx 

44 

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4~2~ 
P.11 

Table 1. Corrected Cost/Ton Values for the Polvad Svstem. 

Input 

mass 

400 TPY 

400 TPY 

100 TPY 

100 TPY 

20 TPY 

20 TPY 

Correct 

Incorrect 

Correct 

Incorrect 

Correct 

Incorrect 

Inlet concentration, ppm 

50 

3,473* 

3,702 

4,622 

4,853 

8,945 

9,191 

100 

1.998 

2.113 

2,771 

2.889 

6.946 

7.079 

150 

1.432 

1.512 

2,246 

2.322 

6.196 • 

6.290 

200 

1.156 

1.213 

1.967 

2.027 

5,802 

5.878 

300 

844 

883 

1.663 

1.705 

5,395 

5.451 

500 

613 

637 

1.389 

1.416 

5.059 

5.101 

700 

522 

539 

1.261 

1.218 

4,912 

4.947 

* Cost (5) per ton of styrene removed. 

2) Durr rotary concentrator system - Cost and fuel usage data for the Durr rotary 

concentrator were received very near the end of the. original styrene controls assessment project. 

I had time to accurately model accurate equipment costs for the Durr rotary concentrator, but I did 

not have time to accurately model fuel usage. (The most accurate model of fuel usage for the 

system would be based on basic principles of combustion and heating.) The fuel usage calculations 

generally over-estimated fuel usage. Knowing that the fuel usage numbers were probably 

inaccurate, I left out the fuel cost from the final Total Annualized Cost calculation. 

Since fuel cost was actually removed from the Total Annualized Cost calculation, the cost 

spreadsheet for the Durr rotary concentrator actually underestimates cost slightly. The incorrect and 

corrected values are shown in Table 2. 

Table 2. Corrected Cost/Ton Values for the Durr Rotarv Concentrator Svstem. 

Input 

mass 

400 TPY 

400 TPY 

100 TPY 

100 TPY 

20 TPY 

20 TPY 

Correct 

Incorrect 

Correct 

Incorrect 

Correct 

Incorrect 

Inlet concentration, ppm 

50 

3,494* 

3,482 

4,493 

3.945 

6.569 

6.022 

100 

1,870 

1.870 

2.404 

2,213 

4.563 

4.373 

150 

1.352 

1,280 

1.721 

1.649 

3.898 

3.827 

200 

998 

986 

1.382 

1.371 

• 3.567 

3.555 

300 

696 

696 

1.094 

1.094 

3.283 

3.283 

500 

469 

469 

875 

875 

3.067 

3.067 

.700 

372 

372 

781 

781 

2,974 

2.974 

Cost (S) per ton of styrene removed. 

45 

4^3 
P.12 

3) Figure 5-5, "Cost curves for a large plant (400 tons per year inlet)" in 

EPA-600/R-96-109 has cost curves for three control technologies plotted on a right-hand axis. This 

right-hand axis is incorrectly scaled with a minimum of negative Sl,000/ton. The affected 

technologies are the EC&C fluidized-bed preconcentrator, the Durr rotary concentrator, and the 

VOC condenser: If these technologies are plotted with a minimum cost of $0/ton, similar to other 

technologies in Figure 5-5, the resulting curves are somewhat altered. 

I have attached a revised version of Figure 5-5. The new figure contains revised curves as 

they would appear, assuming the EC&C preconcentrator is desorbed into a thermal oxidizer. The 

version of Figure 5-5 that appears in EPA-600/R-96-109 is also attached, with the notation 

"ORIGINAL (INCORRECT)". 

I have included a diskette with (revised) cost spreadsheets. If you have any questions, please 

call me at 541-6016. 

46 

44-
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Thermal oxidizer (95% H.R. below 100 ppm) 

— - — Diuiiiiiauuii 

Tliermalrix PADRE 

— -

F r ^ 

•Durr rolary concentrator 

•VOC condenser 

EC&C fluidized-bed preconcenlralor (w/oxidalion) 

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, 

* • m 

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500 600 700 

Figure S-5. Cost curves for a large plant (400 tons per year inlet). 

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246,000 

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Flow rate.cfm (1 cfm = 0.0283 m3/min) 

61.500 41.000 30,750 24,600 20.500 

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% 

fes 

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yad (w/oxidalion) 

alytic oxidizer (95% H.R. below 100 ppm) 

srmal oxidizer (95% H.R. below 100 ppm) 

Thermatrix PADRE 

— —Ro \/n ary concentrator 

C condenser 

— - EC&C fluidized-bed preconcentrator 

*••"-. 

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, 

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— — 

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m — — 

100. 200 300 400 

Concenlration (ppm) 

500 600 700 

Figure 5-5. Cost curves for a large plant (400 tons per year inlet). ORIGINAL (INCORRECT) 
P.15 

Jr± 
P.16 

4-B