&EPA
           United States
           Environmental Protection
           Agency
             Office of Research and
             Development
             Washington DC 2O46O
EPA/625/R-92/012
November 1992
Control of
Air Emissions from
Superfund Sites

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                                        EPA/625/R-92/012
                                         November 1992
            Handbook

Control of Air Emissions from
         Superfund Sites
    Center for Environmental Research Information
       Office of Research and Development
       U.S. Environmental Protection Agency
            Cincinnati, OH 45268

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                                          Notice

    The information in this document has been funded wholly or in part by the U.S. Environmental Protection
Agency. It has been subjected to the Agency's peer and administrative review and approved for publication as
an EPA document. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.

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                                  Acknowledgments

    This manual was prepared for the U.S. Environmental Protection Agency by Radian Corporation, Austin,
TX, under contract to Eastern Research Group (ERG). Heidi Schultz (ERG) and John O'Connor (Radian)
managed the project. Bart Eklund served as the project director and was author of several sections.  Other
authors included Patrick Thompson, Charles Albert, Barry Walker, Whitney Dulaney, William Horton, and
Robert Michna. Radian reviewers included Gunseli Shareef.

    Justice Manning of the EPA's Center for Environmental Research Information (CERI) provided overall
program direction.  Peer review and other support was provided by the following members of the program's
Technical Advisory Committee:

    Jim Durham, U.S. EPA OAQPS
    Patricia Flores, U.S. EPA Region III
    Mark Hansen, U.S. EPA Region VI
    Norm Huey, U.S. EPA Region VIII
    Richard N. Koustas, U.S. EPA ORD/RREL
    Tom Pritchett, U.S. EPA ERT
    Susan Thorneloe, U.S. EPA ORD/AEERL
    William M. Vatavuk, U.S. EPA OAQPS

    This document was reviewed by representatives from the Regional Air-Superfund Program and its
participants.

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                                  Cost Information

    Except where noted, all costs quoted in the manual are in 1992 U.S. dollars. Cost values from prior years
have been adjusted to 1992 U.S. dollars by assuming five percent per year compounded inflation.
                                            iv

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                                   Contents
 r i K: '
Acknowledgments [[[ iii
Acronyms and Abbreviations [[[ . .................................... xiv
Metric Conversions [[[ . ....................... xv

1.0     Introduction ....... , [[[ 1
        1.1   Background [[[ : .............................. 1
        1.2   Technical Objectives [[[ 1
        1.3   Approach [[[ 1
        1.4   Uses and Limitations of the Document [[[ 1

2.0     Development of a Control Strategy [[[ 3
        2.1   Introduction ............. . ...... ...... [[[ 3
        2.2   Generic Strategy for Selecting an Air Emissions Control Approach ................ 3

3.0     Overview of Control Device Selection Guidance [[[ 7
        3.1   Applicability of Control Options [[[ 7
        3.2   Cost-Effectiveness of Control Options [[[ 7
        3.3   References [[[ . ......... . ........................ 20

4.0     Air Emissions-Related Information for Various Remediation Technologies ............ 21
        4.1   Materials Handling [[[ 21
        4.2   Thermal Desorption Treatment [[[ .f>....23

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                              Contents (continued)
                                                                               Page
        5.3   Catalytic Oxidation	49
        5.4   Condensers	55
        5.5   Internal Combustion Engines	61
        5.6   Soil Beds/Biofilters	64
        5.7   Operational Controls	'.	66
        5.8   Membrane Technology	66
        5.9   Emerging/Miscellaneous Controls	71
        5.10  References,	.„	74

6.0     Point Source Controls for Particulate Matter, Metals, Acid Gases,
          and Dioxins and Furans	,	77
        6.1   Fabric Filters	'.	77
        6.2   Electrostatic Precipitators	„..	 80
        6.3   Operational Controls	,	87
        6.4   Wet Scrubbers	87
        6.5   Dry Scrubbers	92
        6.6   HEPAFilters	96
        6.7   References	...	. ...99

7.0     Area Source Controls for VOCs, SVOCs, PM, and Metals	...„ 101
        7.1    Covers and Physical Barriers	 ipl
        7.2   Foams	102
        7.3   Wind Screens	'...	...109
        7.4   Water Sprays	109
        7.5   Water Sprays with Additives	112
        7.6   Operational Controls	;.....	113
        7.7   Enclosures	120
        7.8   Collection Hoods	,	120
        7.9   Miscellaneous Controls „	'.	122
        7.10  References	,	127

            Appendix A    Remediation Control Vendors	...129
            Appendix B     Air/Superfund Program Contacts and Information	134
            Appendix C     Bibliography	138
            Appendix D     Categorization of Commonly Encountered Compounds	145
                                      VI

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                                               Tables

Table                                                                                            Page
3-1     Typical Control Technologies Used for Selected Remediation Technologies arid Pollutants	8

3-2     VOC Controls for Point Sources	9

3-3     Particulate Matter Control Devices for Point Sources	..'.	10

3-4     Applicable Controls for Area Sources	11

3-5     Typical Required Emission Stream and Contaminant Characteristics for Point Source VOC Controls	12

3-6     Typical Required Emission Stream and Contaminant Characteristics for Point Source PM Controls	13

3-7     Typical Required Emission Source and Contaminant Characteristics
          for Area Source VOC and PM Controls	14

3-8     Ranges of % RE for Point Source PM Controls	16

3-9     Estimated APCD Efficiencies for Controlling Toxic Metals	18

3-10    Spray Dryer Control of Selected Organic Pollutants for Hazardous Waste Incinerators	19

3-11    Effectiveness of Acid Gas Controls (% Removal) for Hazardous Waste Incinerators	19

3-12    Costs of Area Source Controls	;....,..	20

4-1     Example Scenarios for Excavation of Contaminated Soil	21

4-2     Comparison of Features of Thermal Desorption and Off-Gas Treatment Systems	24

4-3a    Properties of Off-Gas from Combustion Chamber from On-Site Incineration Systems	25

4-3b    Hazardous Waste Incinerator Emissions Estimates	25

4-4     Example Scenarios for SVE Based on Size of System	27

4-5     Example Scenarios for Air Stripping	'.	29

5-1     Applicability of CAS for Selected Contaminants	40

5-2     Reported Operating Capacities for Selected Organic Compounds	...41

5-3     Equations for Carbon Adsorption Annualized Cost Estimate	43

5-4     Categorization of Waste Gas Streams	45

5-5     Typical Pressure  Drops for an Incineration System	47

5-6     Cost Factors for Thermal Incinerator Capital Costs	50
                                                   vii

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                                        Tables (continued)

 Table                                                                                           Page


 5-7     Cost Factors for Thermal Incinerator Annual Costs	51

 5-8     Common Catalyst Poisons	                     51

 5-9     Destruction Efficiencies of Common VOC Contaminants in a Fluidized Bed Combustor	52

 5-10    Typical Pressure Drops for a Catalytic Oxidation System	53

 5-11    Condensation Temperature Limits for Various Categories of Coolants	58

 5-12    Design Equations for Condensing Systems	„	59

 5-13    Typical Overall Heat Transfer Coefficients in Shell and Tube Heat Exchangers
           for Condensing Vapor-Liquid Media	„...	......_	;      60

 5-14    Annual Cost Factors for Refrigerated Condenser Systems...:	;	61

 5-15    Destruction Efficiencies of ICEs for SVE Systems	63

 5-16    Costs for Some Commercially Available ICE Systems	64

 5-17    Costs for Membrane Module and Other System Costs	71

 5-18    Design Specifications and Costs for Components of Membrane Control Systems	72

 5-19    Effect of Plant Size, Membrane Flux, and Feed Concentration on Capital and Operating Costs
           for Membrane Systems	 _    72

 6-1      Air-to-Cloth Ratios	                 79

 6-2     Approximate Guide to Estimate Gross Cloth Area	79

 6-3      Cost Factors for Fabric Filter Installation and Engineering	81

 6-4     Typical Design Parameters for Electrostatic Precipitators	:	84

 6-5      ESP Drift Velocities for Incinerator Fly Ash in Units of cm/sec	86

 6-6      Cost Factors for Upgrading ESP Construction Material	87

 6-7      Capital Cost Factors for ESPs	 gg

 6-8     Annual Operating Maintenance Costs for ESP Systems	 89

 6-9     Hazardous Waste Incinerator Emissions Estimates	_95

 6-10    Advantages/Disadvantages of HEPA Filters	97

6-11    Remediation. Technologies Compatible with HEPA Filters	98

6-12    Parameters Affecting HEPA Filter Efficiency/Lifetime	98

7-1     Cover Material Effectiveness for Controlling VOC and Particulate Emissions	102

7-2     Major Components for Cover Material Applications	102
                                                 viii

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                                       Tables (continued)

Table
7-3     Advantages/Disadvantages of Cover Materials	

7-4     Cover Material vs. Applicable Remediation Technologies	

7-5     Synthetic Cover Characteristics	••	•	•	

7-6     Parameters Influencing Cover Material Effectiveness	•	•	

7-7     Cover Material Control Efficiency Ranges	,	•	

7-8     Cover Material Sizing/Application Guidelines	,	,

7-9     Cost of Implementing Cover Based Area Control Measures	

7-10    Commercially Available Foams for PM/VOC Emissions Control	

7-11    Advantages/Disadvantages of Foam Systems to Control PM/VOC Emissions	

7-12    Applicable Uses of Foams by Remediation Technology	»	

7-13    Parameters Influencing Effectiveness of Foam-based PM/VOC Suppression Systems	

7-14    Reported PM/VOC Control Efficiencies Using Foam Suppression Systems	

7-15    Foam Costs	••	•	

7-16    Advantages/Disadvantages of Wind Screen Systems	,	

7-17    Applicable Remediation Technologies	„	

7-18    Parameters Influencing Wind Screen Effectiveness	;	;	.	.....

7-19    Reported PM/VOC Control Efficiencies Using Wind Screens	,	

7-20    Wind Screen Sizing	•	

7-21    Wind Screen System Costs	<	•	•	-	

 7-22    Major Components of Water Spray Systems	

 7-23    Advantages/Disadvantages of Using Water to Control PM Emissions	

 7-24   Remediation Technologies Compatible with Water Spray PM Control Systems	

 7-25    Parameters Influencing Water Spray Systems Performance	..:	

 7-26   Reported Paniculate Matter Emission Control Efficiencies for Watering Systems	

 7-27   Additive Processes	'••'	•	•	

 7-28    Common Water Additives	•	•••••

 7-29    Advantages/Disadvantages of Using Water Additives to Control Particulate Matter Emissions.

 7-30    Remediation Technologies Compatible with Water Additives	.....

 7-31    Parameters Influencing Performance of Water Additives	
 Page
....103
  .103

  .104

  .105

  .105

  .105

  .106

  ,107

  ,.107

  ,.108

  ,.108

  ..108

  ..109

  ..110

  ..111

  ..111

  ..111

  ..112

  ..112

  ..113

  ..113

  ..114

  ..114

  ,..115

  ...116

  ...116

  ...117

  ...117

  ...117
                                                   ix

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                                        Tables (continued)
 Table
7-32    Reported Paniculate Matter Emission Control Efficiencies for Water Additives	118
7-33    Additive Costs	            120
7-34    Advantages/Disadvantages of Operational Practices/Procedures	121
7-35    Reported PM/VOC Control Efficiencies for Operational Practices/Procedures	.122
7-36    Advantages/Disadvantages of Enclosures to Control PM/VOC Emissions	;	,..,	122
7-37    Reported Enclosure PM/VOC Control Efficiencies	,....	      123
7-38    Enclosure Costs	,       123
7-39    Advantages/Disadvantages of Hoods to Capture PM/VOC Emissions	„	,	124
7-40    Parameters That Affect Hood Capture Efficiencies	124
7-41    Range of Capture Velocities	         \25
7-42    Hood Design Equations	;	,	         126
7-43    Hood Exhaust System Cost Estimate	         127

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                                               Figures
Figure                                                                                              Page

2-1     Generic strategy for selecting an air emissions control approach. : .............. . ........ . ................ . ........................ 4

3-1     Removal efficiency vs. VOC loading for point source VOC controls ............. ... .......... : ........... . ................... 15

        Relative cost-effectiveness for point source VOC controls ....................... . .................................................. 16

        Typical APCD operating costs in 1988 dollars. .... .............................. . [[[ 17

        Schematic diagram of canister-based granular activated carbon adsorption system ................. .... ............... 37

        Schematic diagram of continuously regenerated carbon adsorption system ........................................ . ....... 38

        Schematic diagram of carbon adsorption system with on-site batch regeneration .............. ; .............. . ......... 38
3-2

3-3

5-1

5-2

5-3

5-4
        Fuel cost/gain vs. concentration of carbon and incineration systems at 50,000 scfm
          of solvent-laden air [[[ • .......... • ..... 42

5-5     Activated carbon systems cost comparison [[[ 44

5-6     Schematic of thermal incineration system with recuperative heat exchanger. ............................................. 45

5-7     Flow chart for categorization of a waste gas to determine its suitability for incineration
          and need for auxiliary fuel and air. [[[ 46

5-8     Incinerator heat balance [[[ 48

5-9     Thermal incinerator equipment cost estimates [[[ 48

5-10   Schematic of catalytic oxidation system with recuperative heat exchanger ................................................. 50

5-1 1   Effect of temperature on destruction efficiency for catalytic oxidation at 10,500 hr1 space velocity ......... 53

5-12   Effect of space velocity on destruction efficiency for catalytic oxidation at 720°F ..................................... 54

5-13   Heat balance for catalytic oxidation [[[ 55

5-14   Catalytic incinerator equipment cost estimates .................... . [[[ 56


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                                        Figures (continued)

 Figure

 5-19    Pressure drop for two filter materials as a function of surface loading rate	,	.......65

 5-20a   Membrane separation system with vacuum pump	,	,..,       .67

 5-20b   Membrane separation system with compressor.	                    67

 5-21a   Membrane concentrator with carbon bed adsorption recovery system	,....,,	68

 5-21b   MTR single-stage membrane system	      .        68

 5-21c   Single-stage membrane separation system with carbon bed adsorber polishing	68

 5-22    Calculated permeate solvent concentrations produced by a membrane with a selectivity of
           200 and. a feed organic vapor concentration of 0.5%	H    70

 5-23    Design procedure for a spiral-wound membrane, based on Pan and Habgood principles	71

 5-24    Capital cost comparison (250 acfm, 100 ppm (CFC-113 feed))	73

         Schematic of direct UV photolysis	73

         Fabric filter process flow diagram	( 78

         Fabric filter equipment cost.	0	go

         Electrostatic precipitator process flow diagram	,..	.....82

         Special collecting electrodes used in electrostatic precipitators	82

         Relationship between collection efficiency and specific collection area for municipal incinerators	,...83

         Effect of gas stream temperature and humidity on collection efficiency for a specific ESP	84

         Relationship between collection efficiency and delivered corona power for municipal incinerators	85

         ESP equipment cost	,                              86

         Purchase costs for two-stage precipitators	       87

        Four common types of wet scrubbing systems	k	90

6-1 la   Dry sorbent injection process	       ....                 93

6-1 Ib   Circulating fluid bed reactor process	4	  93

6-llc   Spray dryer absorption (semi-dry) process	                   93

6-12    PM control system employing HEPA filters	                   96

6-13    Bag-out HEPA filter housing unit	              97

6-14    Pressure drop vs. face velocity curves for specific HEPA filter designs	4	99

        Production of temporary and long-term 3M foams	106
 5-25

 6-1

 6-2

 6-3

 6-4

 6-5

 6-6

 6-7

 6-8

 6-9

 6-10
7-1

7-2
        Wind velocity pattern above a mown field during a 17 m/sec wind blowing at
         right angles to a 4.9 m high wood fence 122 m long of 50% porosity	110
                                                  XII

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                                      Figures (continued)

Figure                                                                                        Pa8e
 7*3     Annual evaporation data for the contiguous United States	<	<	•	119

 7-4     Average PM10 control efficiency for bitumen/adhesive additives	;	.....120

 7-5     Three commonly used hood designs	123

 7-6     Components of a hood exhaust system	••"•»	124
                                                  XIII

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                                Acronyms and Abbreviations
 A/C
 acfh
 acfm
 acmh
 APA
 APC
 APCD
 ARAR

 BTEX

 Btu
 BP
 CAAA
 CAS
 CE
 CERCLA

 CERI

 CFC
 cfm
 CHEMDAT
 CO
 C02
 CPE
 CSPE
 CSTR
 DC
 DE
 DRE
 dscf
 DSI
 EC
 ECO
 EPA
 EPDM
 ESP
 FGD
 GAG
 G/L
 HAP
HC1
HCN
 Air-to-cloth (ratio)
 Actual cubic feet per hour
 Actual cubic feet per minute
 Actual cubic meters per hour
 Air Pathway Analysis (or Assessment)
 Air pollution control
 Air pollution control device
 Applicable or Relevant and Appropriate
 Requirements
 Benzene, toluene,  ethylbenzene, and xy-
 lenes
 British thermal units
 Boiling point
 Clean Air Act Amendments
 Carbon adsorption system
 Control efficiency
 Comprehensive Environmental Response,
 Compensation, and Liability Act
 Center for Environmental Research
 Information
 Chlorofluorocarbons
 Cubic feet per minute
 Emission model
 Carbon monoxide
 Carbon, dioxide
 Chlorinated polyethylene
 Chlorosulfonated polyethylene
 Continuously stirred tank reactor
 Direct cost
 Destruction efficiency
 Destruction and removal efficiency
 Dry standard cubic feet
 Dry sorbent injection
 Equipment cost
 Epichlorohydrin rubber
 Environmental Protection Agency
 Ethylene propylene rubber
 Electrostatic precipitator
 Flue gas desulfurization
 Granular activated carbon
 Gas-to-liquid ratio
 Hazardous air pollutant
Hydrochloric acid
Hydrogen cyanide
 HDP        High-density polyethylene
 HEPA      High efficiency paniculate air
 HF         Hydrogen fluoride
 1C          Indirect cost
 ICE         Internal combustion engine
 IDLH       Immediately dangerous to life/health
 IWS        Ionizing wet scrubber
 LAND?     Emission model
 LEL        Lower explosive limit
 L/min       Liters per minute
 LUST       Leaking underground storage tank
 m          Meter
 MACT      Maximum achievable control technology
 MEI        Maximum exposed individual
 mil          Millimeter
 MMBtu     Millions of Btu's
 MSW       Municipal solid waste (incinerator)
 MWI        Municipal waste incinerator
 NOx        Oxides of nitrogen
 NPL       National Priority List (Superfund)
 NTGS      National technical guidance series
 OSC       On-scene coordinators
 OSHA      Occupational Safety and Health Adminis-
            tration
 PCB        Polychlorinated biphenyl
 PCDD      Polychlorinated dibenzo dioxin
 PCDF      Polychlorinated dibenzo difuran
 PEL        Permissible exposure limit
 PIC         Product of incomplete combustion
 PM         Particulate matter
 PM10       Particulate matter under 10 microns in di-
            ameter
 ppb         Parts per billion
 ppbv        Parts per billion on a volume basis
 ppm        Parts per million
 ppmv       Parts per million volume
 PVC        Polyvinyl chloride
 RA         Remedial action
 RC         Recovery credit
 RCRA      Resource Conservation and Recovery Act
 RD         Remedial design
RE         Removal efficiency
RI/FS       Remedial investigation/feasibility study
ROD        Record of decision
                                                xiv

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                        Acronyms and Abbreviations (continued)
RPM       Remedial project managers
SARA      Superfund Amendments and Reauthoriza-
           tion Act
SCA       Specific collection area (of an electrostatic
           precipitator)
scfrn       Standard cubic feet per minute (25°C, 1
           arm)
SD        Spray dryer
SDA       Spray dryer absorber
SIMS      Surface impoundment modeling system
SITE       Superfund innovative technology evalua-
           tion
SO,        Sulfur dioxide
             SOP       Standard operating procedure
             SVE       Soil vapor extraction
             SVOC     Semi-volatile organic compound
             TCE       Trichloroethylene
             TCI       Total capital investment
             TEC       Total equipment cost
             THC       Total hydrocarbons
             TIC       Total installation cost
             TSDF     Treatment storage and disposal facility
             TSP       Total suspended paniculate
             UEL       Upper explosive limit
             UV       Ultra-violet
             VOC      Volatile organic compound
           Non-metric
Metric Conversions

  Multiplied by
                                                                       Yields metric
MMBtu/hr
op
ft
acfm
dscfm
gal
hp
in
Ib
mil
mile
ton
cuyd
1054.35
0.555556 (°F-32)
0.3048
0.028317
0.028317
3.78541
746
2.54
0.453592
0.0254
1609.344
0.907185
0.76455
MM J/hr
°C
m
acmm
dscmm
L
J/sec
cm
kg
mm
m
metric ton (1,000 kg)
m3
                                                 XV

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                                                   Chapter 1
                                                 Introduction
1.1       Background
  The Superfund Amendments and Reauthorization Act (SARA)
of 1986 mandates that all exposure pathways, including the air
pathway, be considered for sites on the National Priority List
(NPL). Therefore, the remedial project managers (RPMs)  and
on-scene coordinators (OSCs) have had to consider actual  and
potential air emissions from Superfund, i.e.  NPL, sites  and
perform some level of air pathway assessments for their sites. To
assist the RPMs and OSCs, Air/Superfund coordinators have
been appointed in each EPA region to act as the liaison between
the Air and Superfund offices. These Air/Superfund coordinators
have a need for more explicit guidance for determining actual and
potential air emissions. Superfund sites generally  must meet
applicable or relevant and appropriate requirements (ARARs)
such as Section 112 of the Clean Air Act Amendments (CAAA)
of 1990 that designates 189 toxic chemicals that must be con-
trolled from any source that meets certain minimum, designated
emission limits.

   A major emphasis of the Air/Superfund coordination program
has been to  provide technical  assistance to Superfund  staff
concerning air emissions problems at NPL sites. As more NPL
sites move from the remedial investigation/feasibility (RI/FS)
phase  to the remedial design (RD) and remedial action (RA)
phases, formal guidance is needed by RPMs  and OSCs on air
issues related to remediation. This need is exacerbated by new
control requirements demanded by the CAAA, as  well as the
SARA requirements.

 1.2       Technical Objectives
   The overall objective of this program was to develop an easy-
 to-use tool for decision makers to evaluate air emission control
 devices for use with Superfund remediation actions and assist in
 the  selection of cost-effective control options. The  specific
 objectives of this project are to develop:

   1)  Concise descriptions of available control techniques, fac-
       tors that affect their performance, the relative advantages
       and disadvantages of each  technique, and interactive
       effects of control techniques when used in combination;

   2)  Information on the expected emission reduction (i.e. effi-
       ciency) for each control technique when used alone or in
       combination with another technique for both individual
       contaminants and mixtures of contaminants;
  3)   Information pertinent to the selection of optimum control
      techniques and strategies, including possible alterations to
      the remediation approach; and

  4)   Cost information, or estimated total costs, for applying a
      given control technique (or combination of techniques).

1.3       Approach
  Information for this handbook was obtained via a literature
search and a survey of vendors of control devices. No field or
laboratory testing of control devices was performed.

1.4       Uses and Limitations of the  Document
  The intended audience for this handbook are engineers and
scientists involved in preparing Remedial Design (RD) plans for
Superfund sites. The handbook contains a summary of existing
information and an overview of the topic of air emission controls
is presented. The handbook contains background information to
familiarize the user with  the technical basis for each  control
technology. Specific guidance is provided to assist the user in
limiting the choices of potential control technologies and in
selecting a specific set of control technologies  for a given
application.  References are included for users  seeking more
detailed guidance. The user must perform a detailed engineering
evaluation of the control options, gather vendor information, and
perform feasibility studies. The handbook is a screening tool and
is not intended to provide detailed technical specifications for
preparing bid packages.

   Developing guidance for the processes  used to remediate
Superfund sites is a challenge, since many of the cleanup pro-
cesses used at Superfund sites are emerging technologies and
have short operating histories. For these technologies, data on
which to base emission estimates and control needs are  very
limited. Furthermore, each  Superfund  site has a unique set of
contaminants and site conditions. These site-specific factors may
force modifications of the cleanup hardware or operating condi-
tions which could affect air emissions. Obviously, the diverse
nature of sites on the National Priorities List (i.e. Superfund)
results in the guidance being more relevant to some sites than
 others. Site-specific factors must be taken into account when
 selecting emission control approaches, rather than relying solely
 on the generalized guidance contained  in this  document.

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                                                  Chapter 2
                                  Development of a Control Strategy
2.1       Introduction
  Development of an air emissions control strategy and selection
of specific control devices must be an integral part of the overall
remediation process.  Control options should be considered in
tandem with remediation options and not considered indepen-
dently after the final  remediation approach has already been
selected. The type of air emission controls used may affect the
cost-effectiveness of  a given remediation  approach and vice
versa. The ideal time to begin to consider control options (and
remediation options) is when planning the Remedial Investiga-
tion/Feasibility Study (RI/FS).

  A generic control  strategy  is given in  Figure  2-1  that is
applicable to most Superfund sites. The individual steps in the
figure are discussed below. Additional guidance on these topics
may be found in the National Technical Guidance Study (NTGS)
manuals (see Appendix B) or by contacting the Air-Superfund
Coordinator in the appropriate EPA Regional Office (see Appen-
dix B).

2.2      Generic Strategy for Selecting an Air
          Emissions Control Approach

2.2.1    Select Most Promising Remediation
          Technologies
   The two or three most promising remediation scenarios for the
 given site should be identified as early as possible in the RI/FS
 phase. An initial consideration of applicable air emission control
 approaches  should also take place  at the same  time.  This
 information can then be used to plan the RI/FS activities so that
 field data are collected that can be used to assess the need for air
 emission controls  and the probable effectiveness of  various
 control options for the specific site conditions.  All types of
 potential air emissions should be considered: volatile  organic
 compounds (VOCs), semi-volatile organic compounds (S VOCs),
 paniculate matter (PM), and metals.  All potential emission
 sources also should  be considered; for example, any ex-situ
 treatment process likely will result in VOC (if present in the
 waste/soil) and PM emissions from materials handling activities
 (e.g., excavation, transport, waste feeding) and soil/waste stor-
 age, as well as emissions from the treatment process itself.
2.2.2     Estimate Uncontrolled Emissions From
          Remediation
  The overall list of contaminants present at the site should be
examined and target analytes selected based on their frequency
of occurrence at the site, concentration levels in the waste/soil,
representativeness of the overall contamination, and their asso-
ciated risk.  Worst-case and average emission rates should be
estimated for each remediation scenario under consideration.
The preferred estimation approach is pilot-scale FS data from the
site, while modeling using site-specific inputs  is also usually
acceptable.

2.2.3     Estimate Downwind Ambient Air
          Concentrations
  The maximum exposed individual (MEI) should be identified
based on historical site meteorological data.  Air dispersion
modeling should be performed using an EPA-approved model
and using the estimates of uncontrolled emissions as source terms
to estimate maximum short-term and annual average concentra-
tions at the MEI location.

2.2.4    Select Action Levels
  Three types of action level "triggers" may be important.  One,
both short-term and long-term acceptable health-based risk lev-
els at the MEI should always be considered. Since no universally
accepted risk levels exist for short-term or long-term exposure
for either carcinogens or non-carcinogens, the acceptable risk
level must be determined on a case-by-case basis and approved
 by the EPA. Two, applicable or relevant and appropriate require-
 ments (ARARs) (local, state, and Federal) may limit the accept-
 able emission rates from process stacks, e.g., PM emissions from
 incinerators.  Three, odor thresholds at  the MEI may be a
 consideration for some sites. While odors may not pose a health
 threat, they can create a sufficient nuisance to the local commu-
 nity that their control may override other considerations.

 2.2.5     Compare Emission Rates/Downwind
           Concentrations to Action Levels
   The emission rate estimates from any stacks  or vents and the
 downwind  ambient air concentrations at the  MEI should be
 compared to the action levels and any exceedances noted. Ex-
 ceedances indicate the need for emission controls. If no exceed-
 ances are noted, then air emission controls may not be needed. It

-------
           No
                      Calculate
                   required control
                      efficiency
       Do
   any control
approaches meet
     criteria
                   Select optimal
                 remediation/control
                     approach
                                                      Select most promising
                                                       remediation options
                                                     Estimate uncontrolled
                                                        emissions from
                                                          remediation
                                                      Estimate downwind
                                                          ambient air
                                                        concentrations
                                                      Select action levels
                                                     Compare emissions/
                                                   downwind concentrations
                                                       to action levels
                                        Yes
                                                      Identify applicable
                                                    control technologies
                                                Evaluate cost-effectiveness
                                                   of remediation/control
                                                       approaches
                                                           No
                                                                                           Make preliminary
                                                                                            identification of
                                                                                            control options
                                                                         No air emission
                                                                        controls required
Figure 2-1. Generic strategy for selecting an air emissions control approach.

-------
is recommended, however, that the uncertainties associated with
the estimates be taken into account.

  The average control efficiencies required to meet the action
level should be calculated. The overall control efficiency that is
required should be compared to that for the maximum achievable
Control technology  to determine the technical feasibility of
meeting the required control efficiency. If no acceptable controls
exist, then the remediation scenarios should be reconsidered or
some type of pretreatment added.   For example, soil vapor
extraction could be used as a pretreatment prior to excavation if
air emissions of benzeneor other VOCs pose apotential problem.

  Identify Applicable Control Technologies. The two or three
most promising control options for each class of contaminants for
each remediation technology should be selected using the infor-
mation contained in this manual and other references along with
input from engineers with remediation design experience and
from vendors of remediation and control equipment. Selection
criteria are discussed in Section 3.
2.2.6     Evaluate Cost-Effectiveness of Remediation/
          Control Approaches
  Estimate the size of control system or application rate that is
required to meet the control efficiency goal for each remediation/
control approach. Collection of data for full-scale or pilot-scale
remediation and control processes using the specific contami-
nated material of interest should be considered. Estimate the cost
of controls and their impact on the overall cost for remediation.
Estimate the cost-effectiveness of each control approach. Con-
trol options thathave unacceptably high costs should be excluded
from further consideration.  If most or all the control costs are
unacceptably high as a percentage of the total remediation cost,
then the remediation scenarios should be reconsidered.

2.2.7     Select the Optimal Remediation/Control
          Approach
   The cost-effectiveness of the air emission controls should be
used as one input into the overall selection process of a remedial
design.

-------

-------
                                                   Chapter 3
                          Overview of Control Device Selection Guidance
  A summary of the information contained in this manual is
given in this chapter along with tables and figures showing
comparisons of the performance and cost of various control
options. More detailed information about specific remediation
technologies is given in Chapter 4, while detailed information
about specific control technologies is given in Chapters 5,6, and
7. The applicability of control options is discussed below fol-
lowed by a discussion of the cost-effectiveness of various control
options.

3.1      Applicability of Control Options
  Each control technology has relative advantages and disadvan-
tages and no single control option will always be the best choice
for a given remediation technology. Selection criteria for control
technologies include

  •    Demonstrated past use of the control technology for the
       specific application of interest;

  •    Ability to meet or exceed the required average capture
       and/or control efficiency;

       Compatibility with the physical and chemical properties
       of the waste gas stream;

   •   Reliability of control equipment and process;

   •   Capital cost of control equipment;

   •   Operating costs of system (including disposal of byprod-
       ucts or regeneration costs); and

       Permitting requirements.

   As previously stated, the information in this manual is intended
 to be used to screen potential control  options and used in
 conjunction with detailed engineering evaluations, vendor data,
 and feasibility studies to select control technologies.

   A large number of remediation technologies have been used or
 proposed for cleaning up Superfund and other hazardous waste
 sites. Table 3-1 is a list of the control technologies typically used
 at Superfund sites for the most common remediation technolo-
 gies and other emission sources. Past usage is not an infallible
 selection guide, but deviations from typical usages generally
require some justification. Lists of typical volatile, semi-volatile,
and metallic compounds often encountered at Superfund sites are
given in Appendix D.

  Air emission controls can be divided into controls for point
sources of emissions and controls for area sources of emissions.
Point sources include stacks, ducts, and vents from remediation
technologies such as air stripping, soil vapor extraction, thermal
desorption, and thermal destruction. Add-on emission controls
usually can be added readily to point sources. Area sources
include lagoons, landfills, spill sites, and remediation technolo-
gies such as excavation. Air emission controls for area sources
are generally more difficult to apply and less effective than
controls for point sources. Some emission sources such as solidi-
fication/stabilization, bioremediation, and storage piles may be
either point or area sources of emissions. Area sources can be
converted to point sources using enclosures or collection hoods.

   The various VOC controls for point sources are listed in Table
3-2  along  with the  remediation  technologies for which the
controls are potentially  applicable and the relative advantages
and disadvantages of each control option. This same  type of
information is  given in Table 3-3 for PM controls for  point
sources and in Table 3-4 for VOC/PM controls for area sources.
Area source controls tend to be effective for both VOC and PM.
The control technologies listed in Tables 3-2,3-3, and 3-4 have
all been demonstrated at full-scale (except for those identified as
emerging technologies) although not necessarily at Superfund
sites.

   The applicability and effectiveness of control devices for point
 sources will depend on the physical and  chemical properties of
 the waste gas stream. The typical required emission stream and
 contaminant characteristics for point source VOC controls and
 PM controls are given in Table 3-5 and  3-6, respectively. This
 same type of information for area source controls is given in
 Table 3-7.

 3.2      Cost-Effectiveness of Control Options
   The cost-effectiveness of airpollutioncontrol devices (APCDs)
 is very process- and site-specific. In general, a control system is
 designed or modified for each specific application; so, in theory,
 any desired removal or control efficiency can be achieved. In
 practice, a trade-off exists between removal or control efficiency
 and cost.

-------
  Table 3-1. Typical Control Technologies Used for Selected Remediation Technologies and Pollutants
    Emission Source1
                                        VOCs/SVOCs
                                                                     Metals and Particulate Matter
  Materials Handling
       Excavation
  Storage Piles
       Enclosure
  Transport Vehicles


  Roadways



  Thermal Desorption   •



  On-Site Incineration




  Soil Vapor Extraction



  Air Stripping of Water


  Solidification/Stabilization3


  Bioremediation3
     In-situ
     Ex-sltu

 Soil Washing5

 Soil Flushing3

 Solvent Extraction3
                                                                                                              Acid Gases
 Operational Controls
 Foam Operational Controls
 Enclosure

 Polymer Sheeting
 Enclosure
 Cover
 Foam

 NA
 Condensers
 Thermal Incineration2
 Carbon Adsorption
 NA
 Carbon Adsorption
 Catalytic Incineration
 Thermal Incineration
 Internal Combustion Engine

 Carbon Adsorption
 Catalytic Incineration

 Carbon Adsorption
Carbon Adsorption
Carbon Adsorption

Carbon Adsorption

Thermal Incineration
 Water Sprays



 Cover,

 Wind Screen

 Cover
 Gravel/Paving
 Water Sprays
 Water Sprays with Additives

 Cyclone
 Venturi Scrubber
 Fabric Filter
 HEPA Filter

 Cyclone
 Venturi Scrubber
 Ionizing Wet Scrubber
 Wet ESP
 Fabric Filter

 NA
NA


Venturi Scrubber
Filter
Water Sprays


NA
NA

NA

NA
     NA



     NA



     NA


     NA
Wet Scrubber
Dry Scrubber
                                                                         Wet Scrubber
                                                                         Dry Scrubber
                                          NA
    NA
                                                                    Wet Scrubber (if needed)
    NA
    NA

    NA

    NA
 NA-Not applicable
 '  Reduced operation or activity will also limit emissions in most cases
 *  Fuel spiMoak sites.                                  . '   .
 J  Controls not always used. Control system generally must include collection hood.
  A reasonable maximum removal efficiency for various VOC
controls for point sources is shown in Figure 3-1 as a function of
the VOC content of the inlet gas stream. The typical ranges of
cost-effectiveness for these same APCDs are depicted in Figure
3mJL*

  Less  comparative data are available for particulate matter
controls. These types of controls are used almost exclusively at
Superfund sites with thermal treatmentmethods such as incinera-
tion and thermal desorption.
                             .  In general, selection of PM control devices for point sources
                             will not be required since the vendors of thermal  treatment
                             equipment will have already selected control devices for use with
                             their remediation equipment. Limited data for removal efficien-
                             cies for PM controls for point sources are given in Table 3-8.
                             Comparative costs are shown in Figure 3-3.

                               The estimated efficiencies for various APCDs and combina-
                             tions  of APCDs for controlling emissions of toxic metals are
                             shown in Table 3-9. Control efficiencies for various dioxins and
                                                             8

-------
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         Cost effective
         range

         Technology
         effective range
                              Carbon adsorption
                                 Catalytic oxidation
                                Biofiiter
      Condenser
                                                 I.C engine
                                             I   1|_|
                                                Membrane
                                         '1
                                            Thermal processor
                                        Thermal incineration
                            O „ 	
                                      u.v.
        0.1      1.0      10      100     1,000   10,000   100,000


                         VOC concentration (ppm)


    Figure 3-2. Relative cost-effectiveness for point source VOC con-
               trols.
Table 3-8.  Ranges of % RE for Point Source PM Controls
                     RyAsh
PCDD/PCDF
                           Acid Gases
                                                                                     <10 prn
                                                                >10 pirn
Metals
Baghouses —
Wet Scrubbers —
Venturl Scrubbers —
Dry Scrubbers —
ESP 994-
Quench Chambers —
HEPA Filters —
Entrained fraction removed
—
—
90-99+
98% With SDA
—
Entrained fraction removed
—
95-99+
99
95-99+
—
50%
—
99+'
Low
80-95
99+
993
	
99.9+4
99+'
—
80-95
99+
993
	
99.9+4
90-952
40-502
Variable
95-992
8S-992
_
—
1 Lower removal efficiency for mercury.

* For resistive panicles.

4 \Vilh high pressure drop.
                                                              16

-------
               30.0
               10.0
           -§    5.0
           8    2.0
           D)
                1.0
                0.5
                0.2
                              104

            Source: Hesketh, 1991.
                                                               Example wet FGD
Spray dry/dry injection with low
   chemical requirements
          High energy particle
             wet scrubber
                                         Fabric Filter
                                                                                       High Efficiency
                                                                                           ESP
               10s

System capacity (acmh)
                                                                                                                     106
Figure 3-3. Typical APCD operating costs in 1988 dollars.
                                                                17

-------
 Tibia 3-9.  Estimated APCD Efficiencies for Controlling Toxic Metals
Air pollution control device
WS«
VS-20"
VS-60*
ESP-1
ESP-2
ESP-4
WESP"
FF": FF/WS«
PS«
SD/FF; SD/C/FF
DS/FF
ESP-1/WS; ESP-1/PS
ESP-4/WS; ESP-4/PS
VS-20/WS"
WS/IWS'
WESP/VS-20/IWSa
C/DS/ESP/FF; C/DS/C/ESP/FF
SD/C/ESP-1

Ba, Be
50
90 '
98
95
97
99
97
95
95
99
98
96
99
97
95
99
99
99

Ag ._ .
50
90
98
95
97
99
97
95
95
99
98
96
99
97
95
99 ,
99
99
Pollutant
Cr
50
90
98
95
97
99
96
95
95
99
98
96
99
97
95
98
99
98

, As,Sb,Cd,Pb,TI
40
20
40
80
85
90
95
90
95
95
98
90
95
96
95
97
99
95

Hg°
,30 •
20
40
o
o
o
fin
\j\j
50
flfl
O\J
90
en
ou
80
fl^
ou
80
RR
oo
90
Q8
30
85
*  Fluo gases ore assumed to have been preceded (usually in a quench). If gases are not cooled adequately, mercury recoveries will diminish, as will cadmium and
   arsenic recoveries to a lesser extent.                                   •

APCD codes
C      «    Cyclone
WS     .    We» scrubber
             including: sieve tray tower, packed tower, bubble
             cap tower
PS     •    Proprietary wet scrubber design (high efficiency
             PM and gas collection)
VS-20  .    Venturi scrubber, ca. 2-30!n W.G.
VS-60  -    Venturi scrubber, ca. > 60 in W.G.
ESP-1  •    Electrostatic precipitate; 1 stage
ESP-2  -    Electrostatic precipitatar; 2 stages
ESP-4  m    Electrostatic preclpitator; 4 stages
WESP  -    Wet electrostatic preclpitator
IWS    »    Ionizing wet scrubber
OS     -    Dry scrubber
FF     »    Fabric fitter (baghouse)
SD     -    Spray dryer (wet/dry scrubber)

Source: Carroll, 1992.
P
P
                                                                      18

-------
furans are shown in Table 3-10. The effectiveness of various
APCDs for acid gas control is shown in Table 3-11.

  Area source controls also can be applied in theory to achieve
any desired removal or control efficiency. Once again, a practical
trade-off exists between removal or control efficiency and cost.
The control efficiencies of area source controls will vary more
widely than those for point source controls. This variability is
true both from site to site and over time at a given site. Control
efficiencies often may be as low as 50%. Comparative costs per
given area for various area source controls as typically applied
are shown in Table 3-12.
Table 3-10. Spray Dryer Control of Selected Organic Pollutants for Hazardous Waste Incinerators
                                                                     Control system (% removal)
Compound
Dioxins
tetra ODD
penta ODD
hexa ODD
hepta ODD
oota CDD
Furans
tetra CDF
penta CDF
hexa CDF
hepta CDF
octa CDF
SD + ESP

48
51
73
83
89

65
64
82
83
85 •
SD + FF @ high temperature

<52
75
93
82
NA

98
88
86
92
NA
SD + FF @ low temperature

>97
>99.6
>99.5
>99.6
>99.8

>99.4
>99.6
>99.7
>99.8
>99.8
 Source: U.S. EPA, 1987.
 Table 3-11.   Effectiveness of Acid Gas Controls (% Removal) for Hazardous Waste Incinerators
Control system
Dry injection + fabric filter (FF)
Dry injection + fluid-bed reactor + ESP
Spray dryer + ESP
(recycle)
Spray dryer + fabric filter
(recycle)
Spray dryer + dry injection + ESP of FF
Wet scrubber
Spray dryer + wet scrubber(s) + ESP or FF

Temperature1 °C
160-180
230
—
140-160
—
140-160
200
40-50
40-50

HCI
80
90
95+
(95+)
95+
(95+)
95+
95+
95+
Pollutant
HF
98
99
99
(99)
99
(99)
99
99
99

SO,
50
60
50-70
(70-90)
70-90
(80-95)
90+
90+
90+
 1  The temperature at the exit of the control device.

 Source:  U.S. EPA, 1987.
                                                             19

-------
 Table 3-12.   Costs of Area Source Controls
Control
Clay ~
Soil
Wood ohfps. plastic net
Synthetic cover
Short-term foam
Long-term foam
Wind screen
Water spray
Additives Surfactant
Hygroscopic salt
BituVAdhes.
Material cost ($/m2
except as noted)
$4.15
1.33
0.50
4.40
0.04
0.13
40./m
$0.001 (varies)
0.65
2.58
0.02
Comments
Covers, mat, and membrane
Assume 6" deep; does not include soil transport
Chip cost vary with site
Assume 45 ml thickness
Assume 2.5" thick, $0.7/m3 foam
Assume 1 .5" thick, $3.3/m3 foam
Per linear meter
Assuming municipal water cost of $1/1 ,OOOL. Water
requires constant re-application. Water truck rental:
$500/wk.
Costs vary with chemical used
33 References
  Carrol], J.P.  Screening Procedures for Estimating the Air
        Impacts of Incineration at Superfund Sites. EPA-450/1 -
        92-003. Research Triangle Park, NC. February 1992.

  Heskcth, H.E. Air Pollution Control - Traditional and Hazard-
        ous Pollutants. Technomic Publishing Co., Lancaster,
        PA. 1991.

  U.S. EPA. Waste Incineration and Emission Control Tech-
        nologies. EPA/600/D-87/147-5 (NTIS PB87-208336)
        July 1987.
                                                      20

-------
                                                   Chapter 4
                          Air Emissions-Related Information for Various
                                        Remediation Technologies
  This chapter contains background information pertaining to air
emissions and their control for various remediation technologies.
References to general sources of information on process design,
emissions estimation, and costs are provided at the end of the
chapter. The majority of the text is taken directly from a recent
EPA publication on air emissions from the treatment of contami-
nated soil that summarizes existing information on air emissions,
controls, and cost for various remediation technologies (Eklund,
et al., 1992c). A second source of information is a recent EPA
publication giving emission factors for remediation technologies
(Thompson, et al., 1991).

  For each remediation technology, a typical remediation sce-
nario for Superfund sites is  given followed by a discussion of
potential air emissions.  References are given for emission
estimation procedures, and applicable control technologies are
identified.

4.1    Materials Handling
  Materials handling covers such activities as excavation, dump-
ing, grading, short-term storage, and sizing and feeding soil or
waste into treatment processes. Information on equipment and
operating practices is available in Church, 1981 and U.S. EPA,
199la.  The discussion below primarily addresses excavation.

4.1.1    Typical Remediation Scenario for
        Superfund Sites
  Excavation and removal of soils contaminated with fuels is a
common practice at Superfund sites. Excavation and removal
may be the selected remediation approach or it may be a neces-
sary step in a remediation  approach involving treatment. If
removal is the preferred approach, the excavated soil typically is
transported off-site for  subsequent disposal at a landfill. If the
soil contains large amounts of fuel or highly toxic contaminants,
the soil may need to be treated off-site prior to final disposal.
Excavation activities are also typically part of on-site treatment
processes such as incineration, thermal desorption, batch bio-
treatment, land treatment, and certain chemical and physical
treatment methods.  The soil is excavated and transported to the
process unit and the treated soil typically is put back into place on
the site.

   The rate of materials handling operations at Superfund sites
 tend to be controlled by factors such as safety concerns, storage
 capacity or treatment capacity, rather than being limited by the
operational capacities of the equipment that is used. For these
reasons, actual materials handling rates tend to be far below
typical handling rates at construction sites (Church, 1981). Typi-
cal scenarios for excavation at Superfund sites are given in Table
4-1.

Table 4-1.  Example Scenarios for Excavation of Contaminated Soil
                                    Scenario
Parameter
Units    Small   Medium   Large
Soil moved per scoop
No. scoops per hour
Total volume of soil moved
Excavation pit:
dimensions:
area
Storage pile:
dimensions:
area
m3
#/hr
m3/hr

m
m2

m
m2
1
50
50

10x5x1
50

5x5x2
65
2
75
150 •

10x15x1
150

5x10x3
140
• 4
60
240

10x12x2
120

8x10x3
188
Source: Eklund, etal., 1991 a.
   Since digging soil and immediately transferring it directly to
 transport vehicles or treatment systems is rarely  feasible or
 efficient, soil will be handled several times. In most cases, soil
 will be excavated and placed into a temporary holding area and
 then handled one to two more times on-site. Elevated levels of
 VOC and PM emissions are possible each time the soil is handled.

 4.1.2   Potential Air Emissions
   The exchange of contaminant-laden soil-pore gas with  the
 atmosphere when soil is disturbed and diffusion of contaminants
 through the soil both contribute to VOC emissions from excava-.
 tion. Multiple potential emission points exist for each of the
 various soils handling operations.  For excavation, the main
 emission points of concern are emissions from:

   • Exposed waste in the excavation pit;
   • Material as it is dumped from the excavation bucket; and
   • Waste/soil in short-term storage piles.

   In addition, emissions of VOC, particulate matter, nitrogen
 oxides, etc. will also occur from the engines of the earth-moving
 equipment. While these emissions will not require any additional
 control devices (beyond those provided by the manufacturer), the
                                                         21

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  equipment emissions should be considered when evaluating any
  air monitoring data.

    The magnitude of VOC emissions depends on a number of
  factors, including the type of compounds present in the waste, (he
  concentration and distribution of the compounds, and the poros-
  ity and moisture content of the soil. The key operational param-
  eters are the duration and vigorousness of the handling, and the
  size of equipment used. The longer or more energetic the moving
  and handling, the greater likelihood that organic compounds will
  be volatilized. The equipment size influences volatilization by
  affecting the mean distance a volatilized molecule has to travel to
  reach the air/solid interface at the surface of the soil. In general,
  the larger the volumes of material being handled per unit opera-
  tion, the lower the percentage of VOCs that are stripped from the
  soil. Control technologies for large area sources such as excava-
  tion are  relatively difficult to apply and are often much less
  effective than controls for point sources.

   Paniculate matter (PM) em issions will depend primarily on the
  particle size distribution of the soil, its moisture content, the wind
  speed, and the operating practices that are followed. The longer
  or morecnergetic the moving and handling, the greater likelihood
  that PM emissions will occur.

   The success of excavation and removal for a given application
 depends on numerous factors with the three key criteria being: 1)
 the nature of the contamination; 2) the operating practices fol-
 lowed; and 3) the proximity of sensitive receptors. Each of these
 criteria is described below.

   The magnitude of emissions from soils handling operations
 will vary with the operating conditions. Add-on control technolo-
 gies are available for minimizing VOC and PM emissions, but
 they arc relatively ineffective and costly to implement. Control of
 emissions can also be achieved by controlling the operating
 conditions within preset parameters. The rate of excavation and
 dumping, the drop height, the amount of exposed surface area,
 the length of time that the soil is exposed, the shape of the storage
 piles, and the dryness of the surface soil layers will all influence
 the levels of VOC and PM emissions. Large reductions in
 emissions can be achieved by identifying and operating within
 acceptable ranges of operating conditions.

   Since some  release of  volatile contaminants is inevitable
 during excavation and removal unless  extreme measures are
 taken (e.g., enclose the remediation within a dome), the proxim-
 ity of downwind receptors (i.e., people) will influence  whether
 excavation is an acceptable option. Excavation of contaminated
 areas that abut residential areas, schoolyards, etc. may require
 more extensive controls, relocation of the affected population, or
 remediation only during certain periods (e.g., summertime for
 school sites).

4.13   Emission Estimation Procedures
  Relatively limited VOC emissions or emission rate data for
excavation are available. The process of measuring emission
rates from dynamic processes, such as excavation, is difficult and
costly, and has rarely been attempted. The factors that govern
emissions from materials handling are very complex. During
  excavation, for example, the physical properties of the soil that
  control the vapor transport rate (e.g., air-filled porosity)  are
  changing with time and the concentration of contaminants may
  be rapidly decreasing.

    Predictive equations for estimating emissions from excavation
  and dumping are under development (Eklund, et al., 1992a).
  These models are based on estimating emissions from diffusion
  through the soil and from the loss of saturated pore-space gas to
  the atmosphere. The predictive equations require assumptions
  about the size of each scoop of soil, the dimensions of the soil
  scoops and the excavation pit, and the shape of the soil after it is
  dumped. Further assumptions are required about the air and soil
  temperatures and the length of time that dumped soil is exposed
  before it is covered with more soil or with an emissions barrier.
  The equations generally predict high levels of emissions. For dry,
  porous soils containing low ppb levels of contaminants, most or
  all of the more volatile VOCs are  assumed to be lost to the
  atmosphere during soils handling. For sites with moist soils and
  ppm levels of contaminants, however, only 5 to 10% of the VOCs
  are assumed to be emitted to the atmosphere during each handling
  step. More field measurement data are needed to validate these
 assumptions. .

   Soils handling operations such as excavation substantially
. increase VOC emission rates from contaminated soil over base-
 line rates (Eklund, et al., 1989). The increase in emissions is
 typically a factor of ten or more, and the increased emission rate
 decays exponentially back  to near the baseline rate over short
 time periods (e.g., 4 days). A database of baseline emission rate
 measurement data (Eklund, et al., 1991a) is available. Other
 estimation procedures and field data are summarized in Eklund
 etal., 1992c.

   Particulate matter emissions can be estimated using the empiri-
 cal equations  in Cowherd, et al., 1988. Emissions for topsoil
 removal, earth moving, and truck haulage are reported to range
 from about 1 to 6 kilograms  of paniculate matter per vehicle per
 kilometer traveled.

4.1.4  Identification of Applicable Control
        Technologies
   A number of methods are available for controlling VOC and
paniculate matter emissions from soils. In general, any method
designed primarily for paniculate control will also reduce VOC
emissions and vice versa. Compared to point source controls,
VOC emission controls for excavation and. other area sources are
difficult to implement and only moderately effective. Controls
such as water sprays or foams will alter the percent moisture, bulk
density, and average heating value of the soil and may affect
treatment and disposal options.

  VOC emission controls for soil area sources are discussed in
Section 7 and include:

  • Covers and physical barriers;
  • Temporary and long-term foam covers;
  • Water sprays;
  • Water sprays with additives;
                                                        22

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  • Operational controls;                   •
  • Complete enclosures;
  • Wind screens; and                          ,
  • Collection hoods.

4.2     Thermal Desorption Treatment
  Mobile process units designed for soil remediation and the use
of asphalt kilns for soil remediation are discussed in this section.
The best currently available source of information is an engineer-
ing bulletin prepared by the U.S. EPA (U.S. EPA, 1990a).Design
and operating information for thermal desorption systems are
given in an EPA Guidance Document being prepared (Troxler, et
al., 1992). Air emissions and cost data have been summarized
(Eklund, et al., 1992c).

4.2.1   Typical Remediation Scenario for
        Superfund Sites
  In the thermal desorption process, volatile and semi-volatile
contaminants are removed from soils, sediments, slurries, and
filter cakes. This process typically operates  at temperatures of
200°-1000°F but often is referred to as low temperature thermal
desorption to differentiate it from incineration. At these lower
temperatures, thermal desorption promotes physical separation
of the components rather than combustion. Contaminated soil is
removed from the ground and transferred to treatment units,
making this an ex situ process. Direct or indirect heat exchange
vaporizes the volatile compounds  producing an off-gas that
typically is treated before being vented to the atmosphere. After
it is excavated, the waste material is screened to remove objects
greater than 1.5" in diameter (de Percin, 1991 a). In general, three
desorber designs are used:  an indirectly fired rotary  dryer,
internally heated  screw  augers, or  a fluidized bed (de Percin,
1991 b). The treatment systems include both mobile process units
designed specifically for treating soil and asphalt kilns,  which
can  be adapted to  treat soils. Typical  characteristics of the
processes and off-gas streams for mobile units and rotary drum
units at asphalt plants are summarized in Table 4-2.

   Because thermal desorbers, in some cases, may operate near or
above 1000°F, some pyrolysis and oxidation may occur in
addition to the vaporization of water and organic compounds.
Collection and control equipment such as afterburners, fabric
filters, activated carbon, or condensers prevent the release of the
contaminants to the atmosphere. Thermal desorbers can create up
to seven process residual streams: treated soil, oversized media
rejects, condensed contaminants, water, paniculate control dust,
clean off-gas, and spent carbon (de Percin, 1991b).

4.2.2    Potential Air Emissions
   Thermal desorbers effectively treat soils, sludges and filter
cakes  and remove volatile and semi-volatile organic compounds
from the material. Some higher boiling point substances such as
polychlorinated biphenyls (PCBs) and dioxins also may be
removed and thus be present in the off-gas. Inorganic compounds
are not easily removed  with this process, although some rela-
tively volatile metals such as mercury may be volatilized. Tem-
peratures reached in thermal desorbers generally do not oxidize
metals (de Percin, 1991 a). VOC removal is enhanced if the soil
contains 10-15 percent moisture prior to treatment since water
vapor carries out some VOCs.
  Point sources of air emissions from thermal desorption vary
widely with each process. The stack of an afterburner vents
combustion products, as does a fuel-fired heating system if the
combustion gases are not fed into the desorber.  The fuel-fired
heating system typically operates with propane, natural gas or
fuel oil. If emissions controls consist of abaghouse, scrubber, and
vapor phase carbon adsorber, the stack will vent small concentra-
tions of the original contaminants, as well as products of any
chemical reactions that might occur. Relative to incineration, the
volume of off-gas from the treatment chamber may be smaller,
there is less likelihood of creating dioxins and other oxidations
products, and metals are less  likely to partition to the gas-phase
(de Percin, 199 la).

  Fugitive emissions from area sources may contribute signifi-
cantly to the total air emissions from a remediation site. Probably
the largest source is excavation of the contaminated soil. Other
sources may include the classifier, feed conveyor, and the feed
hopper. Fugitive emissions from the components of the thermal
desorption system and controls are possible as well. Emissions
may also emanate from the waste streams such as exhaust gases
from the heating system, treated soil, paniculate  control dust,
untreated oil from the oil/water separator, spent carbon from
liquid or vapor phase carbon  adsorber, treated water, and scrub-
ber sludge.

4.2.3    Emission Estimation Procedures
  The volatile and semi-volatile contaminants under remedia-
tion are the species emitted if no destruction or other chemical
treatment has taken place. The sources emitting these VOC's
may include excavation, soil handling, classifier, oversize ob-
jects rejected by the classifier, feed conveyor, feed hopper,
control stack, and fugitive emissions from the entire thermal
desorption system and from waste streams. Combustion products
are emitted when a destructive control such as an afterburner is
used and also when the heating system  is fuel-fired. In some
cases, pyrolysis occurs to a certain degree in the dryer so products
from these reactions may also be emitted. If scrubbers are used to
treat VOC's or combustion gases, then an additional category of
species is emitted.

  Theoretical models  based on fundamental principles .have
been proposed for predicting the evolution of volatile com-
pounds from soil in the thermal desorption process, but these
models are not practical for use as apredictive tool (Lighty, et al.,
 1990). In practice, an assessment of the applicability of thermal
desorption for a given  site will not be based  on  modeling
calculations, but will be based on  the types of contaminants
present in the soil, the physical properties of the soil, and the
results of any bench-, pilot- or full-scale test runs. In most cases,
the process conditions such as temperature and residence time in
the desorber  can be modified to yield  the desired removal
efficiency, though heavier weight compounds such as those in
No. 6  fuel oil may present problems for systems with relatively
low operating temperatures.  The cost to operate at these process
conditions, however, will dictate whether thermal desorption is
 competitive with other remediation options.

   A mass balance equation to estimate an emission rate for a
 volatile compound leaving the desorber using removal efficien-
 cies obtained from test runs is given in Eklund, et al., 1992c. This
                                                          23

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  Tabla 4-2.  Comparison of Features of Thermal Desorption and Off-Gas Treatment Systems


Estimated number of systems
Estimated number of contractors
Mobility
Typical site size (tons)
Soil throughput (tons/hr)
Maximum sol! feed size (inches)
Heat transfer method
Soil mixing method
Discharge soil temperature (°F)


Soil residence time (minutes)
Thermal desorber exhaust gas
temperature (°F)

Rotary dryer
40-60
20-30
Fixed and mobile
500-25,000
10-50
2-3
Direct
Shell rotation and lifters
300-600 •
600-1, 200 b

3-7
500-850 a
800-1,000"
Gas/solids flow Co-current or counter-current
Atmosphere
Afterburner temperature (°F)
Maximum thermal duty (MM Btu/hr) •
Heatup time from cold condition (hrs)
Cool down time from hot condition (hrs)
Total petroleum hydrocarbons
Initial concentration (mg/kg)
Final concentration (mg/kg)
Removal efficiency (%)
Caitoon steel materials of construction
AHoy materials of construction
Hot oil heal transfer system
Motion salt heat transfer system
Electrically heated system
Not used on all systems
Oxidative
. 1,400-1,800
15-85
0.5-1.0
1.0-2.0
800-35,000
<1 0-300
95.0-99.9






Asphalt plant
aggregate dryer
100-150
No estimate
: Fixed
0-10,000
2^-100
2-3
Direct
Shell rotation and lifters
300-600


3-7
500-850

Co-current or counter-current
Oxidative
1,400-1,800'
50-125
0.5-1.0
1.0-2.0
Not reported
Not reported
Not reported







Thermal screw
18-22
g
Mobile
500-5,000
3-15
1-2
Indirect
Auger
300-500 "
600-900 "
1 ,000-1 ,600 •
30-70
300

N/A
Inert
Generally not used
7-10
Not reported
Not reported
60-50,000
ND-5,5000
. 64-99







Conveyor furnace
•|

Mobile
500-5,000
5-10
1-2
Direct
Soil agitaters
300-800


3-10
1 ,000-1 ,2000

Counter-current
• Oxidcitivs
1,400-1,800
10
0.5-1.0
Not reported
5,000
<10.0
>99.9






Total duly of thermal desorber plus afterburner
 Source:   Eklund, et al., 1992c.
 equation does not include emissions from excavation or other
 handling of contaminated soil nor does it include fugitive emis-
 sions from the desorber system or from liquid and solid phase
 waste streams. Neither are'combustion gases emitted from the
 heating system and exhaust gases from afterburners included in
 this estimation method. However, tabulated emissions data for a
 number of thermal desorption systems are included. Most of the
 studies  cited include data about contaminant concentrations in
 the soil  directly before and after treatment, data which can yield
 information aboutpoint source air emissions from the desorption
process itself. These studies do not include the change in concen-
tration before and after excavation due to volatilization. Simi-
larly, little data are available on fugitive emissions from the parts
of the process that do not include the desorption chamber and
from the other waste streams.
4.2.4    Identification of Applicable Control
     •   Technologies
   The control of volatile organic  emissions is crucial to the
overall success of thermal desorption remediation of contami-
nated soils. Because the process uses physical separation driven
by heat, the vaporized contaminants would simply be transferred
from one medium (soil) to another (air) if no emission controls
were employed. The types of controls include both destruction
and  separation  technologies. Typically two to six controls in
series are chosen to suit the specific .VOC contaminants present
and the other pollutants of concern. Liquid phase and solid waste
streams are usually treated on site or stored for subsequent off-
site treatment.

  Asphalt kilns will have similar air emission control devices as
for mobile thermal desorption units, except that no VOC controls
typically  are employed and the air flowrates are higher requiring
some differences in design parameters.
                                                         24

-------
  Off-gases from the desorber typically  pass first through a
particulate control device. Particles that become entrained in the
off-gas stream may be removed with:

  • Cyclones;
  • Venturi scrubbers; or
  • Fabric filters.

  Collected particulates usually are returned to the incoming
waste stream and retreated with the soil.

  VOC control devices include:

  • Condensers;
  • Fume incinerators; and
  • Carbon adsorption.

  Condensers serve to remove VOCs while fume incinerators
(i.e.,  afterburners) destroy the VOCs. Carbon adsorption is
sometimes added to either of these primary VOC control meth-
ods as a final polishing step.  Exhaust gases from destruction
controls may be treated in an acid gas scrubber. Gases are first
cooled to saturation temperature then passed through a packed-
bed absorber or spray tower where acidic gases are neutralized
with caustic (sodium hydroxide) solution or dissolved into water.

   Other emissions control techniques include rerouting combus-
tion off-gases to a dryer, using treated water for dust control, and
passing an inert gas such as  nitrogen through the desorber as
explosion prevention. Ultraviolet rays have been used to destroy
dioxin in the condensate from the thermal desorption of contami-
nated soils (Helsel and Thomas, 1987).

4.3     On-Site Incineration

4.3.1   Typical Remediation Scenario for
         Superfund Sites
   A broad range of technologies fall into the category of thermal
incineration. The most common incineration technologies in-
clude liquid injection, rotary kiln, and multiple hearth. The most
common design for the remediation of contaminated soils, how-
 ever, are rotary kilns. Remediation by on-site thermal destruction
 using a transportable incinerator is discussed in this section.
 Shipment of contaminated soils and wastes to a larger, permanent
 off-site unit may also be an option for a given site, but system
 design and selection of control options is not generally a consid-
 eration. Although incineration is a well-established technology,
 the evolution of mobile or transportable incinerators is a rela-
 tively new development. The literature on  incineration is very
 extensive. The best sources of information on air emissions from
 incineration are two recent reviews (Oppelt, 1987) and (Eklund,
 etal., 1989).

   In broad terms, thermal destruction of hazardous waste is an
 engineered process in which controlled combustion is used to
 reduce the volume of an organic waste material  and render it
 environmentally safe. Incineration is a flexible process capable
 of being used for many waste types including solids, gases,
 liquids, and sludges.
  A typical system includes the waste feed system, primary and
(in most cases) secondary combustion chambers, and exhaust gas
conditioning system. The largest part of the waste destruction
usually takes place in the  primary combustion chamber.  As
mentioned earlier, for contaminated soils this chamber is usually
a rotating kiln. Gases formed in the primary combustion chamber

Table 4-3a. Properties of Off-Gas from Combustion Chamber from
           On-Site Incineration Systems
    Parameter
                             Units
Value
Air flowrate
Temperature
Oxygen content
Pressure drop
ACFM
°F
%
In. H20
30-50,000
1,400-1,800
3
10-15
Table 4-3b. Hazardous Waste Incinerator Emissions Estimates
EPA*
conservative
estimated
efficiencies
Particulate
matter
Hydrogen chloride
(HCI)
Sulfur dioxide (SO2)
Sulfuric Acid (H2SO4)
Arsenic
Beryllium
Cadmium
Chromium
Antimony
Barium
Lead
Mercury
Silver
Thallium
PCDD/PCDF"
99+%

• —

—
—
95
99
95
99
95
99
95
85-90
99
95
—
Typical
actual
control
efficiencies
99.9+%

99+

' 95+
99+
99.9+
99.9
99.7
99.5
99.5
99.9
99.8
40-90+
99.9+
99+
90-99+
Typical range
of emissions
rates
0.005-0.02
gr/dscf
10-50mg/NM3

30-60
2.6
1-5ng/Nm3
<0.01-0.1
0.1-5
2-10
20-50
10-25
10-100
10-200
1-10
10-100
1-5ng/NM3
 * Based on spray dryer fabric filter system or 4-field electrostatic
   precipitator followed by a wet scrubber.
 ** Total all cogeners

 Source:   Donnelly, 1991.
 are then routed to a secondary combustion chamber, or after-
 burner, where any unburned hydrocarbons or products of incom-
 plete combustion can be oxidized. Typical off-gas properties for
 on-site incineration systems are summarized in Table 4-3.

 4.3.2   Potential Air Emissions
   The air emissions associated with full-scale thermal destruc-
 tion are primarily stack emissions of combustion gas. However,
 some additional evaporative emissions may occur from equip-
 ment leaks and waste handling. Full-scale, off-site incineration
 units may vent all emissions from waste handling and transfer
 activities to the combustion chamber as make-up air. The air
 emissions for on-site incinerators are similar to off-site units,
 except that  on-site waste handling activities have a greater
 likelihood of being uncontrolled. Stack heights for transportable
 units may be in the range of 40-100 ft. (Good engineering practice
 stack height will not apply unless large structures are present.)
                                                            25

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  Tire fugitive emissions sources associated with thermal treatment
  likely will be ground-level.

    Emissions from incineratois include: undestroyed organics,
  metals, paniculate matter, nitrogen oxides (NOx), carbon monox-
  ide (CO), acid gases, and products of incomplete combustion
  (PICs). The cause of each of these pollutants and typical levels of
  emissions are discussed in Eklund, et al., 1992c. Fugitive emis-
  sions associated with excavation, storage, and handling of the
  feed material also must be considered when assessing potential
  air impacts from incineration.

    The wide variety in design and operation of incinerators makes
  it difficult to predict air emissions. However, extensive research
  has been done to determine the range of unburned hydrocarbon
  and PIC emissions that can be expected from full-scale incinera-
  tors. In general, incinerators treating  wastes must achieve a
  required  destruction and removal efficiency of at least 99.99%
  for RCRA wastes and 99.9999% forPCB- or dioxin wastes. The
  remaining 0.01 % or 0.0001 % of the waste can be assumed to pass
  through the system uncombusted (Eklund, et al., 1989). How-
  ever, in addition to unbumed hydrocarbons there may be some
  additional reactions in the combustion process that may produce
  a number of simpler organic compounds, called PICs. PICs may
  include dioxin, formaldehyde, and benzo(a)pyrene  and other
  polynuclear aromatic hydrocarbons. Possible  causes of PIC
  emissions include low temperatures due to quenching, residence
  time short circuits due to nonplug flow and/or unswept recesses,
 and locally high waste/oxygen concentration ratios due to poor
 microscale mixing.
   The  metals introduced to the incinerator via the waste feed
 stream are not destroyed. Depending on their boiling point, they
 can either be volatilized or remain as solids. Volatilized metals
 will exit the stack as a gas, condense or adsorb onto particles in
 the stack gas stream, or be captured in the wet scrubber. Metals
 associated with paniculate matter (PM) will be captured in the
 PM control device. Non-volatilized metals can be fluidized and
 swept up into the combustion gas or leave the incinerator in the
 bottom ash.

   The waste feed, auxiliary fuel, and combustion air can all serve
 as sources for paniculate emissions from an incineration system.
 Paniculate emissions may result from inorganic salts and metals
 which cither pass through the system as solids or vaporize in the
 combustion chamber and recondense as solid particles in the
 stack gas. High molecular weight hydrocarbons may also con-
 tribute to paniculate emissions through several possible mecha-
 nisms. RCRA requirements for paniculate emissions call for a
 limit of 0,08 grains/dscf corrected to 7% O2 (U.S. EPA, 1990b).

  Achieving  high  levels of destruction of organic wastes  is
directly related to combustion chamber temperature: the higher
the temperature, the greater the DRE of organics (for a given
combustion gas residence time and degree of turbulence). Unfor-
tunately, the fixation of nitrogen and oxygen to form NO also
increases with combustion  temperatures above 1600°F."NO
emissions caused by this mechanism are referred to as thermal
NO,. Also if bound nitrogen atoms are present in the waste (e.g.,
amines), additional NOX emissions, called  fuel N0x, will be
formed. In such cases, two stage combustion or emissions con-
  trols may be needed. Carbon monoxide emissions are generally
  low (<25 ppmv) in incinerators due to the high operating tem-
  peratures and excess oxygen maintained in the process.
    Hazardous waste incineration also will produce acid gases.
  These include oxides of sulfur (SO ), and halogen acids  (HC1
  HF,andHBr).

  4.3,3    Emission Estimation Procedures
    Simple mass balance equations for estimating incineration
  emissions with an assumed DRE have been published (Eklund,
  et al.,  1989 and IT,  1992). The equations cover VOCs, PM,
  metals, and acid gases. Both of these documents summarize
  typical operating rates, control efficiencies, etc.

    Models have been reported for direct fired, high temperature
  rotary kiln systems that predict the temperature of the solid bed
  and kiln exit gas as a function of measurable physical parameters
  such as kiln rotational speed, burner firing rate, soil feed rate, etc.
  (Troxler, et al.,  1992). These  models theoretically could be
  combined with thermal stability data and oxygen content of the
  kiln gas data to predict the destruction efficiency of incinerators.

   Emissions of PICs, both the amount and the type, will vary
 greatly from unit to unit depending on design and waste  feed.
 Data are unavailable to generate emission factors.

   The production of acid gases (HC1, SO2, HBr, and  HF) is
 determined by the respective chlorine, sulfur, bromine, and
 fluorine contents in the waste and fuel feed streams. The concen-
 trations of these elements range widely amongst different wastes;
 consequently, the resulting acid gas emissions also will show
 wide variability.

   NOx is usually only a concern for wastes with high nitrogen
 content. Typical NOx emissions for an incinerator may be on the
 order of 100-200 ppmv (dry basis), or expressed on a fuel basis
 0.12-0.33 Ibs per MMBtu (Eklund, et al., 1992c). CO emissions
 from incinerators also are not considered a major problem since
 most systems are designed to be fired with excess air (i.e. oxygen
 rich)  to ensure complete combustion of organic  material  to
 carbon dioxide. Vendors typically guarantee CO emissions less
 than 100 ppmv (dry basis) and actual measured CO levels are
 often lower.

 4.3.4   Identification of Applicable Control
        Technologies
  Unlike other soil remediation technologies, incineration, which
 converts organics into carbon dioxide and water, does not require
 additional add-on VOC controls. However, additional controls
 are usually required to reduce emissions of acid gases, paniculate
 matter (PM), and metals. After the combustion gases leave the
 incinerator, they may be routed through a variety of air pollution
control devices including gas conditioning, paniculate removal,
and acid gas removal units. Gas conditioning is accomplished
with equipment such as waste heat boilers or quench units.

  Typical paniculate matter removal devices include:

  •  Venturi scrubbers;
  •  Wet electrostatic precipitators;
                                                        26

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  •  Ionizing wet scrubbers; and
  •  Fabric filters.

  Acid gas removal units include:

  •  Packed, spray, or tray tower absorbers;
  •  Ionizing wet scrubbers;
  •  Wet electrostatic precipitators; and
  •  Spray dryer adsorbers.

  The absorbers generally will use a caustic solution. Units used
to treat soil contaminated with halogenated solvents generally
will be required to meet RCRA requirements governing HC1
emissions.

4.4    Soil Vapor Extraction
  A number of reports and articles have been published recently
that provide useful information regarding soil vapor extraction
(SVE) systems. The best single source of information on SVE
design and operation is a recent EPA report (Pedersen and Curtis,
1991). Another key reference is a recent overview paper (Johnson,
et al., 1990). Air emissions from SVE systems are addressed in
Eklund, et al., 1992b and Eklund, et al., 1992c.

4.4.1   Typical Remediation Scenario for
        Superfund Sites
  Soil vapor extraction is one method used for the treatment of
soil contaminated with volatile hydrocarbons. The process some-
times is referred to as soil venting, vacuum extraction, aeration,
or in-situ volatilization. In general terms, soil  vapor extraction
removes volatile organic constituents from contaminated soil by
creating sufficient subsurface airflow to strip contaminants from
the vadose (unsaturated) zone by volatilization. As the contami-
nant vapors are removed, they may be vented directly to the
atmosphere or controlled in  a number of ways.  Among the
relative advantages of SVE over other remediation approaches
are that no materials handling operations are necessary and the air
emissions are released  from  a point source and  thus can be
controlled readily.

  Soil vapor extraction has been used widely to remediate sites
contaminated with gasoline or chlorinated solvents (e.g., TCE).
It is also used sometimes to minimize migration of vapors into
structures or residential areas during other types of remediation.
By its nature, SVE is an bn-site, in-situ treatment method.  SVE
often is used in conjunction with or following other remedial
measures such as excavation  of subsurface waste bodies, re-
moval (pumping) of any hydrocarbon lens that is present, or air
stripping of contaminated ground  water.

  Typical SVE systems include extraction wells, monitoring
wells, air inlet wells, vacuum pumps, vapor treatment devices,
vapor/liquid separators and liquid phase treatment devices (if
contaminated water is extracted in the process). Example sce-
narios for SVE systems at Superfund sites are  given in Table 4-
4. An option sometimes employed is to introduce the air at the air
inlet well into the saturated zone (i.e. groundwater table). This
technique, referred to as air sparging, acts to  strip some of the
volatile and semi-volatile compounds from the ground water.
Table 4-4.  Example Scenarios for SVE Based on Size of System
Scenario
Parameter
Exhaust gas
flowrate
Exhaust gas
velocity
Exit gas temp.
-No controls
-Carbon
-Catalytic
oxidation
Stack height
Stack diameter
Units
m 3/min
cfm
m/sec.


°C
°C
°C

m
m
Very
Small
1.4
. 50
3.0


50
25
320

3.0
0.10
Small
14
500
7.4


50
25
320

4.6
0.20
Medium
85
3,000
12.5


50
,25
320

7.6
0.38
Large
425
15,000
14.2a


50
25
320

9.1
0.46
• Assume three adjacent stacks each handling 5,000 cfm. The flow is split to
  lower the velocity of the exiting gas to typical design levels to minimize
  corrosion of the stack.

Source: Eklund, et al., 1992b.
 Another option is to heat the air entering the inlet wells to enhance
 the volatilization of less volatile, higher molecular weight con-
 taminants, such as diesel fuel.

   Steam-assisted SVE is another option that has been used for
 improving the removal efficiency  of VOCs and SVOCs. The
 steam can be injected via inlet wells. A mobile treatment system
 also has been demonstrated that treats blocks of soil (7 x 4 ft. x
 up to 20 ft. deep) at a rate of about 3 nvVhr (U.S. EPA, 1991b).
 Augers are used to stir the soil as steam is injected. The treated
 area is covered by a shroud (ducted hood) and all vapors are
 extracted and sent to control devices (see Section 4.4.3).

 4.4.2   Potential Air Emissions
   The contaminants removed from the soil by SVE systems and
 hence present in  the off-gas generally have vapor  pressures
 greater than 1.0 mm Hg at 20°F. The tendency of the organic
 contaminants to partition into water or to be adsorbed onto soil
 particles  also affects the off-gas composition, as do  the com-
 pounds' water solubility, Henry's Law constant, and  soil sorp-
 tion  coefficient. The  soil temperature affects each of these
 variables and hence the rate of vapor diffusion and transport. The
 concentration of contaminants that are initially present will also
 affect their relative partitioning between vapor and liquid phases,
 and the amount that is solubilized or adsorbed. The time that the
 contamination has been present is also an important  factor, as
 mixtures of contaminants will generally  become depleted of their
 more volatile components over time through volatilization. This
 process,  referred to as weathering, will tend  to cause SVE to
 become progressively less applicable  as the  site ages. It also
 affects the operation of the SVE system, as the more volatile
 components are typically removed first and the composition of
 the vapors collected and treated varies over time.
                                                           27

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    VOC loading rates in the off-gas can be 500-600 kg/day or
  higher. The air emissions associated with soil vapor extraction
  systems come primarily from the stack. Stack heights are typi-
  cally 12-30 feet and usually only one stack is used. Additional
  releases of volatile organics may occur from the treatment of any
  contaminated water that is  extracted. Fugitive emissions are
  considered negligible due to the negative pressure throughout
  most of the system.

  _ Emissions include untreated volatile organics from the extrac-
  tion process. Removal and emissions of semi-volatile organic
  compounds will occur also, though with less efficiency than for
  VOCs. Lesser amounts of air emissions associated with the
  control system may occur also. Due to the variety of technologies
  used, stack emissions may include products of incomplete com-
  bustion, nitrogen oxides, particulate matter, carbon monoxide,
  acid gases and any otherpossible products of these technologies.
  Of primary concern, however, are the volatile organics emitted
  from the point sources. Percent levels of carbon dioxide in the
  off-gas may occur and would suggest that in-situ biodegradation
  is occurring in conjunction with the S VE. The ambient air drawn
  through the soil would raise the oxygen content of the soil-gas
  and thus promote biodegradal;ion.

   The emission rate of VOC compounds over time from continu-
  ously operated SVE systems tends to show an exponential-type
  decay curve. If the system is stopped and then restarted, however,
  the VOC emission rate returns to near the original rate unless the
 remediation is nearing completion. Apparently, shutting off the
 vacuum allows the  soil-gas equilibrium to become re-estab-
 lished. Due to this behavior, the most efficient method of opera-
 tion is to run the SVE system only for a part of each day or week,
 i.e. operate in a "pulsed" mode.

 4A3   Emission Estimation Procedures
   The factors that govern vapor transport in the subsurface are
 very complex and no practical, accurate theoretical models for
 predicting emissions or recovery rates for SVE systems exist.
 During operation of SVE systems, the vacuum that is applied to
 the soil and the resulting pressure gradient is the dominant factor
 in determining the flowrate of vapors. Subsurface vapor flow
 equations based onDarcy's Law have been published thatpredict
 the flowrate of vented gas, but these equations are not useful as
 a predictive tool due to the large variability in air permeability
 among and within sites (Johnson, et al., 1990). In practice, field
 tests typically are performed to evaluate the potential effective-
 ness of SVE for a given site. The field tests may be either a pilot-
 scale demonstration of SVE or tests of the air permeability. This
 information is used to determine the number of wells required to
 remediate the site and the spacing of the wells, and also may yield
 information about the off-gas stream to be treated.

  A simple screening model  is available based on  historical
vaporextractionrates at sites where SVE systems have been used
(Eklund, et al., 1992b). The guidance given in the screening
model document encourages the user to provide site-specific
extraction rate and vapor concentration data, but conservative
default values also are provided.
  4.4.4   Identification of Applicable Control
          Technologies
    As the vapors are removed from the soil they are either
  discharged to the atmosphere or treated to reduce air emissions.
  If the hydrocarbon content is high enough, direct combustion is
  theoretically possible. However, because concentrations typi-
  cally drop significantly during removal, natural gas or some other
  fuel will be needed to maintain combustion. Also, for safety
  reasons, dilution air typically  is added to maintain the VOC
  concentration below the lower explosive limit (LEL). In some
  cases, the wells may be shut down for a period of time to allow
  subsurface vapor pressures to re-equilibrate, thus yielding con-
  centrations sufficient to sustain a flame. For lower levels of
  hydrocarbons, catalytic oxidation may be effective.  Carbon
  adsorption systems are used often but they may be costly to
  implement and generally are not acceptable for high-humidity
  gas streams.

   A recent survey indicates that the exhaust from about 50% of
  SVE systems is vented directly to  the  atmosphere with no
  controls (PES, 1989). The trend, however, is for VOC controls to
  be required. For those systems with  controls, the most viable
  options are:

   1)  Activated carbon adsorption;
   .2)  Catalytic oxidation;
   3)  Thermal incineration;
   4)  Internal combustion engine; and
   5). Miscellaneous control approaches.

   The first three treatment options are the most commonly used
 for large SVE systems such as those used  at Superfund sites or
 refineries. Internal  combustion engines (ICE) are a common
 choice for control of emissions for small systems such as those
 used at small Leaking Underground Storage Tank (LUST) sites.
 Theoretically, removal efficiencies of 95-99% for VOCs should
 be achievable with any of these control options, though actual
 control efficiencies in the field may be closer to 90%. Control
 efficiencies for minor components of the off-gas stream may be
 lower.

   The miscellaneous control devices that potentially may be
 applicable for controlling VOC emissions from SVE systems
 include:

   • Condensers;
   • Packed bed thermal processors; and
   • Biofilters.

   Condensers using chilled water or other refrigerants can re-
 move anywhere from 50 to 90% of VOCs from concentrated
 streams (>5000 ppmv VOCs). Biotreatment requires time to
 establish an active culture of microbes and careful control of soil
 moisture, temperature, and  air flow patterns to maintain the
 efficiency of the microbial action.

  The mobile treatment system using steam-assisted SVE has a
gas treatment system that consists of (U.S. EPA, 1991b):
                                                        28

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  • Scrubber;                                        '•.-'••--
  • Cyclone separator;               .   • :
  • Cooling system;
  • Carbon adsorption system; and
  • Compressors.                        . ,.

  Particulate matter entrained in the process air stream is re-
moved in the  scrubber. The air is then sent  to the cyclone,
separator where water droplets are removed. Heat exchangers.are,.
then used to cool the gas and remove more water and organic,
compounds. The process air stream from the coojing'system is,
passed through activated carbon to remove VOCs. The cleaned
air stream is then sent to a compressor where it'is heated and
routed back to the treatment shroud. Air emissions from the
system are minimal in terms of both volume and mass loading.

4.5     Air Stripping of Contaminated Water
4.5.1   Typical Remediation Scenario for
        Superfund Sites
   Air strippers are used widely to remove chlorinated solvents
and other VOCs from contaminated ground water. Air stripping
is amass transfer process in which volatile contaminants in water
are evaporated (stripped) into air. The contaminated water is
introduced at the top of a packed-tower through spray nozzles and
allowed to slowly flow down through the column or tower. The
packing media acts to retard the water flow and increase the
effective surface area of the system. Air is introduced countercur-
rent to the direction of water flow. The saturated air containing
the volatiles is emitted from the top of the column or routed to a
control device. The treatment system may also contain wells,
separators, and vessels for treating inorganic contaminants. Ex-
ample scenarios for air stripping systems at Superfund sites are
given in Table 4-5.

4.5.2   Potential Air Emissions
   The primary source of emissions from air  stripping is the
stripper exhaust, and VOCs are the major pollutants of concern.


 Table 4-5.  Example Scenarios for Air Stripping

                              Typical Value
Parameter Units
Total influent L/min
liquid flowrate gpm
Column height m
Column diameter m
Exhaust gas rrrVmin
flowrate cfm
Stack height m
Stack diameter m
Structure m
dimensions
Exit gas velocity m/sec
Exit gas temperature °C
Ambient temperature °C
Gas/liquid ratio (vol/vol)
(G/L)
Stripping efficiency %
Small
570
150
7.6
1.2
29
1,020
8.5
.0.31
7.6x1.2x1.2

6.4
20
20
50

99+
Medium
2,840
750 •
9
3.6
140
5,000
10
0.61
9.0x3.6x3.6

8.0
2.0
20
50

99+
Large
5,700
1 ,500
14
3.6
285
10,000
15
0.91
13.0x3.6x3.6

7.3
20
20 •
50

99+
  Source: Eklund, et al., 1991b.
For systems without control  devices, the  exhaust is vented
through a short stack, typically a (3-6 ft) pipe, at the top of the
column. For systems with control devices, the airflow from the
column usually is vented down to the control device at ground
level. A short stack (15-20 ft) is used after the control device.

  In addition to the exhaust stack, other emission sources may
exist. Any place upstream of the air stripping tower where water
is in  direct contact with  the atmosphere, such as separators,
holding tanks, treatment tanks, or conduits, is an emission source.
Fugitive losses from pumps, valves, and flanges usually are not
significant due to the dilute nature of the water contamination.

  The important parameters affecting the emission rate for  a
given compound from an air stripping unit include: the concen-
tration of the contaminant in the influent  to the stripper, the
influent flowrate, the stripping efficiency of the tower, and the
effectiveness of any control technologies that are in place. The
stripping efficiency will depend on a number of factors includ-
ing: the compound's Henry's Law constant, the type of packing
material in the tower, and the gas to liquid contact ratio within the
tower.

4.5.3   Emission Estimation Procedures
   For a given liquid treatment rate, the magnitude of the uncon-
trolled air emissions  from an air stripper are governed by the
effectiveness of the liquid-to-air mass transfer in the stripper. A
stripping efficiency of 100% for volatile organic compounds is a
reasonable, conservative assumption. A number of equations and
associated computer models  are available to aid the system
designer in selecting the appropriate tower height, gas to liquid
ratio, packing material, etc. to optimize the mass transfer and
meet the performance goal in a cost effective manner (e.g., U.S.
EPA, 1990c).

   A simple screening model is also available that estimates VOC
emissions using a mass balance approach,  influent mass load-
ings, and the Henry's Law constants for the contaminants present
 (Eklund, etal., 1991b).

4.5.4   Identification of Applicable Control
         Technologies
   The use of a control device can reduce emissions by one to two
 orders of magnitude (i.e. 90-99% control). VOC control from air
 strippers is possible by:

   • Carbon adsorption;  or
   • Catalytic oxidation.

   Thermal oxidation also could be used with air strippers if the
 VOC concentration was sufficiently high,  but no such use has
 been found in the literature. In addition to these three VOC
 control methods, flares have been used at some landfills for the
 control of emissions from air strippers (Vancit, et al.,  1987).
 Emissions of PM, SVOC, and metals are all negligible, so no air
 emission controls for these compounds are needed.

 4.6     Solidification/Stabilization
   General information about solidification and stabilization is
 contained in Cullinane, etal., 1986. Extremely limited data exists
                                                          29

-------
  about air emissions from these types of processes. The discussion
  in this section was taken largely from Thompson, et al., 1991.

  4.6.1   Typical Remediation Scenario for
          Super/and Sites
    Stabilization and solidification technologies are gaining in-
  creased use as Superfund site remediation methods. The goal of
  these processes is to immobilize the toxic and hazardous con-
  stituents in the waste, usually contaminated soil or sludge. This
  can be accomplished by several means:

    1)   Changing the constituents into an immobile (insoluble)
        form;

    2)   Binding them in an immobile, insoluble matrix; or

    3)   Binding them in a matrix which minimizes the material
       surface exposed to solvents (groundwater) which could
       leach the hazardous constituents.

    Several types of stabilization and solidification technologies
 exist as alternatives forremedial action. A few of these processes
 involve in-situ treatment; however, most generally require exca-
 vation and other soil handling activities. Nearly all the commer-
 cially available stabilization and solidification technologies are
 proprietary.

    Solidification and stabilization processes usually are batch
 operations, but may be continuous and all follow the same basic
 steps. Wastes are first loaded  into the mix bin (wastes  are
 sometimes dried before addition to the bin), and other materials
 for the solidification or stabilization are added. The contents of
 the bin then are mixed thoroughly. After a sufficient residence
 time, the treated waste is removed from the bin. Treatment rates
 are 25-100 tons/hr for in-situ processes and up to 130 tons/hr for
 cx-situ processes (U.S. EPA, 1990d and U.S. EPA, 1989a). The
 material usually is formed into blocks and allowed to cure for up
 to several days. The blocks then can be placed in lined excava-
 tions on-site. Note: This description does not apply to in-situ
 treatment methods,  which use a variety of techniques (from
 applied high voltage to injection of stabilizing agents) to immo-
 bilize  the contaminated waste in-place without excavation or
 soils handling.

   Typical raw materials used in stabilization processes include
 fly ash, portland cement, cement kiln dust, lime kiln dust, or
 hydrated lime. Other additives that may be used to solidify or
 encapsulate wastes include asphalt, paraffin,  polyethylene, or
 polypropylene.

 4.62   Potential Air Emissions
  The  primary source of air emissions from stabilization and
 solidification processes is volatilization of organic contaminants
 in the waste. Up  to 90% of the VOCs are lost during mixing and
 curing (Weitznian, et al., 1989). Volatilization can occur during
 waste handling activities such as soil excavation and transport or
during the process of mixing the binding agents with the waste.
Also, some evaporative emissions will occur from waste even
after stabilization, especially during the curing period immedi-
ately after the blocks  are formed. As shown in lab studies the
  largest fraction of volatile loss occurs during the mixing phase
  because heat may be required to assist mixing or is generated by
  exothermic stabilization reactions (Weitzman, et al. 1989).

    Particulate matter emissions from a full-scale  system were
  found to be about 2.5 Ib/hr (Ponder and Schmitt, 1991).

  4.6.3   Emission Estimation Procedures
    In general, VOC emissions from stabilization and solidifica-
  tion processes will depend on the type and concentration of the
  VOCs in the waste, the duration and thoroughness of the mixing,
  the amount of heat generated in the process, and the average batch
  size processed.  The longer or more energetic the mixing and
  processing, the greater likelihood that organic compounds will
  volatilize. The volatile losses also will increase as the tempera-
  ture of the waste/binder mixture increases. Binding agents with
  high lime contents generally cause highly exothermic reactions.
  The batch  size influences volatilization by affecting the mean
  distance a volatilized molecule has to travel to reach the air/solid
  interface at the surface  of the stabilized waste. The larger the
  block of material, the lower the rate of volatilization.

   In addition to volatile emissions, stabilization and solidifica-
  tion processes will generate fugitive dust emissions.  Possible
  sources of fugitive dust emissions include storage of raw mate-
  rials, preparation of the binding agents, transfer of wastes into the
  mixing bin, removal of the treated material from the mixing bin,
  and replacement of the material  at the site after processing.

   Little information exists about the fate of volatile contaminants
  in wastes treated by stabilization and solidification methods. A
  literature search found no available field data on air emissions at
  Superfund sites using this type of remediation technology. Based
 on laboratory studies, however, about 40-80% of  the volatile
 contaminants in the treated waste is estimated  to eventually
 evaporate (Weitzman, etal., 1989). Most of the loss occurs within
 60 minutes of mixing the waste with binding agents. Thompson,
 et al., 1991  give a simple mass balance equation for estimating
 emissions.

   Particulate matter emissions for stabilization and solidification
 processes can be estimated using emission factors for soil han-
 dling (see Section 4.1).

 4.6.4   Identification  of Applicable Control
         Technologies
  Emission controls for excavation, storage, and feeding of the
 waste to the process  unit were  covered in Section 4.1.4. In
 general, solidification/stabilization is not the remedy of choice
 for wastes with high levels of VOCs and therefore VOC emis-
 sions are not usually a major concern. The only reference in the
 literature to emission controls from solidification/stabilization is
 a solidification system processing 12 tons/hr enclosed  in a
 building (Ponder and Schmitt, 1991). Approximately 40,000 ft3/
 min of air from the building was routed to PM and VOC control
 devices. Emissions were controlled by introducing the gas stream
 to a venturi scrubber, followed  by a  mist eliminator, an air
preheater, a disposable prefilter, and finally two parallel carbon
adsorption systems.
                                                          30

-------
  For in-situ processes, several options or combination of op-
tions could be appropriate for controlling VOC or PM emissions:
  • Collection hood;                      •       ,

  • Windscreens;
  • Temporary foams;                            ,,    [,
  • Water sprays;
  • Water sprays with additives;
  • Enclosures; and                                 ,
  • Operational controls.                     ,

4.7     Bioremediation
4.7.1   Typical Remediation Scenario for Super/and
        Sites
  Bioremediation at Superfund sites may be either in-situ or ex-
situ. Ex-situ biodegradation generally refers to treatment pro-
cesses where an aqueous slurry is created by combining soil or
sludge with water and then biodegraded in a self-contained
reactor or in a lined lagoon. This is an emerging technology and
often is referred to as slurry biodegradation. Ideally, the waste is
decomposed into carbon dioxide and water. Background infor-
mation is available in U.S. EPA,  1990e and Thompson, et al.,
1991.

  In-situ treatment employs the natural microbiological activity
of soil to decompose organic constituents. Systems that try to
enhance this natural biological activity typically use injection
wells to provide an oxygen source (such as air, pure oxygen, or
hydrogen peroxide) to stimulate aerobic degradation or add
nutrients to support the growth of waste-consuming microorgan-
isms. In some cases, microorganisms may be added to the soil that
have the ability to metabolize specific contaminants of interest.
  In-situ bioremediation at Superfund sites also may involve
sequential isolation and treatment of waste areas using processes
that closely resemble ex-situ processes except that it may not be
necessary to excavate, pump, or otherwise transfer the waste
material prior to treatment. Ex-situ processes are more developed
and demonstrated than in-situ processes at this time.

  Two main objectives behind using slurry biodegradation are:
to destroy the organic contaminants in the soil or sludge, and,
equally important, to reduce the volume of contaminated mate-
rial. Slurry biodegradation can be the sole treatment technology
in a complete cleanup system, or it can be used in conjunction
with other biological, chemical and physical treatment methods.

  Systems have a number of components, all of which could be
emission sources: mix tank, bioreactor  system (continuously
stirred tank reactor or CSTR), or lined lagoon. Since aerobic
treatment is the most common mode of operation for slurry
biodegradation, aeration must be provided to the bioreactors by
either floating or submerged, aerators or by compressors or
spargers. Other  typical system components are a separation/
dewatering system, a clarifier for gravity separation, and waste-
water storage tanks.

   Biodegradation is actually only one of several  competing
mechanisms in biotreatment. For ex-situ processes, the contami-
nants may also be volatilized, undergo chemical degradation, or
be adsorbed onto the soil particles. For in-situ processes, these
same pathways exist along with leaching. The overall contami-
nant removal achieved by biotreatment processes represents the
combined effect of all of these mechanisms. Volatilization may
account for the disappearance of the majority of VOCs being
treated.

4.7.2   Potential Air Emissions
  Typical emissions from biotreatment process are evaporative
losses of volatile and semi-volatile organic compounds. If the soil
is handled  or mixed,  though, some emissions of paniculate
matter may occur. Combustion  emissions from the  process
equipment are also possible.

  The air emissions from slurry biodegradation processes can
either be area or point sources. For processes using open lagoons,
emissions come from the exposed surface of the lagoon. On the
other hand in systems  using above-ground self-contained reac-
tors, the primary source of emissions is usually a process vent.

  In bioslurry processes the emissions of concern are usually
VOCs. The soils handling steps required to deliver the contami-
nated soil to the treatment unit may also emit significant amounts
of VOCs and PM. Emissions from soils handling are addressed
elsewhere in this document.

  In open lagoons, the primary environmental factors, in addi-
tion to the biodegradability and volatility  of the waste, which
influence air emissions are process temperature and wind speed.
Emissions tend to increase with an increase in surface turbulence
due to wind or mechanical agitation. Temperature affects emis-
sions through its influence on microbial growth. At temperatures
outside the band for optimal microbial activity, volatilization will
increase. Emissions from self-contained reactors are also deter-
mined by reactor design parameters such as the amount of air or
oxygen used to aerate the slurry. Higher gas flow will strip more
volatiles out of solution and increase air emissions.

  Little information exists on volatile losses from slurry biodeg-
radation processes. Slurry processes have only recently become
commercially available and field experience to date is limited.
However, data on air emissions from wastewaster biotreatment
processes are available. The percentage of each contaminant that
is volatilized will vary greatly depending on the physical proper-
ties of the contaminant and the design of the treatment system.
Based on field  studies of an aerated impoundment treating
contaminated water, as much as 20% of each compound may be
volatilized depending on its volatility and  biodegradability
(Eklund, et al., 1988). Percentage emissions for soil and waste
treatment would be expected to be higher.

4.7.3    Emission Estimation Procedures
  Although no models have been developed explicitly for esti-
mating VOC or PM  emissions for bioremediation processes
treating contaminated soils or waste, several public-domain PC
models are available for estimating air emissions from a variety
of  other biotreatment options, principally surface impound-
ments. The two most commonly used models are CHEMDAT-7
(U.S.  EPA, 1989b) and the Surface Impoundment Modeling
System (SIMS). Both CHEMDAT-7 and SIMS are based on
mass transfer and biodegradation models developed by EPA.
                                                          31

-------
    While not appropriate for Superfund sites, land treatment is a
  bioremcdiation process that is somewhat analogous to the types
  of remediation performed atSisperfund sites. A PC-based model,
  LAND? (U.S. EPA, 1989b), is recommended by the EPA to
  predict the emission rates resulting from the land treatment of
  wastes. Sensitivity studies doae using these models show that
  under typical conditions they predict that 35-80% of the applied
  volatilcs will be emitted to the air and the remainder degraded
  (Coovcr, 1989).

  4.7.4  Identification of Applicable Control
         Technologies
   When the air emissions from slurry biodegradation processes
  arc released through a process vent, standard VOC air pollution
  control technologies can be applied. Common alternatives for
  controlling VOC vent emissions include:

   • Carbon adsorption;
   • Thermal incineration or oxidation; and
   • Catalytic oxidation.

   For the relatively low VOC levels and low gas flows from
  bioreactors, carbon-based VOC emission controls are generally
 the best choice. Since the vent stream will likely contain only
 dilute amounts of VOCs, relatively large amounts of auxiliary
 fuel must be fired in either thermal or catalytic oxidizers.

   When the air emissions from slurry biodegradation processes
 are area air emission sources, applying air pollution  control
 technologies is more difficult. The best approach is generally to
 use a vapor collection hood to capture any VOC emissions and
 then route those emissions to a standard control device. Other
 area source control approaches (e.g., foams,  covers) generally
 are not applicable to in-situ bioremediation since the controls are
 designed to inhibit the transfer of gases between the soil and the
 atmosphere. While these approaches reduce VOC emissions,
 they will also limit the replenishment of oxygen to the soil and
 may cause anaerobic conditions to develop.

 4.8     Separation Techniques
 4.8.1    Typical Remediation Scenario for Superfund
         Sites
  Three remediation technologies are  described below: soil
 washing, solvent extraction, and soil flushing. These  are all
 primarily separation processes and further treatment of the col-
 lected  contaminants typically will be required. They have not
 been used widely at Superfund sites. Soil washing is an ex situ
 process in which contaminated soil is excavated and fed through
 a water-based washing process. It operates on the principle that
 contaminants can be dissolved or suspended in an aqueous
 solution or removed by separating clay and silt particles and the
 associated adhered contaminants from the bulk soil. The aqueous
 solu tion containing contaminants may be treated by conventional
 wastewater treatment methods (U.S. EPA, 1990f).

  Most organic and inorganic contaminants bind chemically or
physically to clay or silt soil particles, which in turn adhere to
larger sand and gravel particles primarily by compaction and
adhesion. Particle size separation by washing enables the con-
  taminated clay and silt particles (and the bound contaminants) to
  be concentrated. Separating the sand and gravel from the small
  contaminated soil particles significantly reduces the volume of
  contaminated soil, making further treatment or disposal much
  easier. The larger particles may be returned to the site (U.S. EPA
  1990g).

    Removal efficiencies range from 90-99 percent for volatile
  organic compounds and 40-90 percent for semi-volatile com-
  pounds, so the wastewater streams may contain high levels of
  organic compounds and be an emission source.

    Excavation and removal of debris and large objects precedes
  the soil washing process. Sometimes water is added to the soil to
  form a slurry thatcanbepumped. After the soil is prepared for soil
  washing, it is mixed with wash water and sometimes with extrac-
  tion agents. At this point, several separation processes occur. Soil
  washing generates four waste streams:

    1)  Contaminated solids separated from the washwater;
   2)  Wastewater;
   3)  Wastewater treatment sludges and residual solids; and
   4)  Air emissions.

   Solvent extraction differs from soil washing in that it employs
 organic solvents  rather than aqueous solutions to extract con-
 taminants from the soil. The remediation process begins with
 excavating the contaminated soil and feeding it through a screen
 to remove large objects. In some cases, solvent or water is added
 to the waste in order to pump it to the extraction unit. In the
 extractor, solvent (e.g., liquefied propane and butane) is added
 and mixed with the waste to promote dissolving of the contami-
 nants into the solvent. Up to five waste streams may result from
 the solvent extraction process:

   1)   Concentrated contaminants;
   2)   Solids;
   3)   Wastewater;
   4)   Oversized rejects; and
   5)   Air emissions.

   Typically, solvent extraction units are designed to produce
 negligible air emissions, but significant levels of emissions may
 occur during waste preparation (U.S. EPA, 1990g).

   Soil flushing differs from soil washing and solvent extraction
 in that it is an in situ process in which the solvent is sprayed over
 the contaminated area, percolates through the soil and  dissolves
 the contaminants. Elutriate is collected in a series of wells and
 drains.

4.8.2   Potential Air Emissions
  In addition to the contaminants that may volatilize, the solvents
themselves may be cause for concern. Products of aerobic and
anaerobic decomposition  are  also possible.  No field data for
emissions from any of these processes has been identified.

  In the soil washing process the greatest potential for emissions
of volatile contaminants occurs in the excavation, feed prepara-
tion, and extraction process. Collected  emissions from these
                                                         32

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processes typically are treated by carbon adsorption or incinera-
tion (U.S. EPA, 1990f). Because soil washing occurs in liquid
and solid phases, volatile compounds emitted evolve primarily
due to their vapor pressures in these phases. The waste streams
also have the potential to be sources of VOC emissions.

  Solvent extraction also may produce emissions during excava-
tion and soil transport and from contaminated oversize rejects
(U.S.  EPA, 1990g). Because the solvent recovery process in-
volves vaporization of the solvent, fugitive emissions are pos-
sible from this as well as other stages of the solvent process,
including the waste streams.

  Emissions from soil flushing may emanate from the soil
surface, solvent storage vessels and spray system,  and from
locations where the contaminant-laden flushing solution sur-
faces.

4.8.3   Emission Estimation Procedures
  No equations or models for predicting the air emissions from
these processes have been identified.

4.8.4   Identification of Applicable Control
        Technologies
  Carbon adsorption and fume incineration are  typical controls
used to treat collected emissions. In solvent extraction, volatile
solvents are recovered and recycled.

4.9     Other Emerging Technologies
  A broad range of technologies fall under this heading, with
most being some type of physical or chemical waste treatment
methods. Included in this category are emerging chemical treat-
ment methods such as:

  • Chemical oxidation using ozone or hydrogen peroxide;
  • Hydrolysis of alkyl halides and other organics; and
  • Dechlorination (e.g., using lime);

and physical treatment methods such as:

  • In-situ thermal treatment or vitrification;
  • Electrokinetics; and
  • Ground freezing.

  These  methods have in common that they  are undergoing
development, little or no data are available regarding levels of air
emissions, and air emission controls have not been evaluated for
these applications. Further information is available in U.S. EPA,
1990h and U.S. EPA, 1991c. General considerations are dis-
cussed below.

  In general terms, a chemical treatment method is one in which
a reactive compound (or compounds) is added  to the contami-
nated groundwater or soil to react with pollutants and form less
harmful products. As the name implies, the effectiveness of this
type of treatment depends greatly on the chemical properties of
the pollutants. An example of this type of method is ozone
treatment of contaminated groundwater.  In this process, con-
taminated groundwater or wastewater is mixed in a continuous
reactor with ozone and other oxidizing agents. The oxidizers
react with the organic contaminants to form CO2 and water.

  Physical treatment involves the addition of energy or another
treatment agent to physically transfer the pollutants to another
state in which they are easier to dispose of or treat. The path of
physical transfer can be adsorption, absorption, dissolution, or a
change of state such as evaporation. An example of this method
is in-situ vitrification. Electrodes are placed in the ground and a
large current is applied. The soil heats and fuses. The electrodes
are removed after the ground has sufficiently cooled (e.g., after
one year).

  The air emissions associated with chemical and physical waste
treatment techniques that may be used at Superfund sites have not
been characterized adequately for most methods. A broad spec-
trum of technologies are included in this category, and the types
and sources of air emissions may vary greatly. For most chemical
and physical treatment methods,  however, the  emissions of
primary concern are  VOCs, with emissions of semi-volatile
organic compounds and particulate matter also of potential
concern.  Emissions are usually from either ground  level area
sources or low-level point sources. Point sources typically are
associated with the treatment method, while area sources usually
are associated with the handling of contaminated soil or water.

  In general, two types of process air emission sources can be
associated with chemical and physical treatment. First, transfer
of the contaminants from the liquid- or solid-phase to air may be
an inherent consequence of the treatment method. For example,
in-situ thermal treatment volatilizes a significant fraction of the
soil contaminants. In some cases, these air emissions are con-
trolled by using a hood to collect the emissions and route them to
an add-on control device for VOCs, such as carbon adsorption
units. Second, fugitive emissions can be generated as a by-
product of the treatment method. For instance, in ozone treatment
of contaminated  water, trace emissions of unreacted organic
contaminants and ozone may occur.

  Additional fugitive  emissions from physical and chemical
treatment methods can result from leaking valves, pumps, and
flanges in the system, as well as from transfer or handling of the
untreated contaminated material. Equipment leaks may be regu-
lated under.the CAAA regulations.

4.10   References
  Church, H. Excavation Handbook. McGraw-Hill, NY, NY.
      1981.

  Coover, J.R. Air Emissions From Hazardous Waste Land
      Farms. Presented at the Spring National AIChE Meeting,
      April 2-4,  1989.

  Cowherd, C., G. Muleski, and J.  Kinsey. Control of Open
      Fugitive Dust Sources. EPA-450/3-88-008. U.S. EPA,
      RTP, NC.  September 1988.

  Cullinane, M.,  L. Jones, and P. Malone. Handbook for Stabi-
      lization/Solidification of Hazardous Waste. EPA/540/2-
      86/001 (NTIS PB87-116745). June 1986.
                                                         33

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 Damlc, A.S. and T.N. Rogers. Air/Superfund National Tech-
    nical GuidanceStudy Series: AirStripper Design Manual.
    EPA-450/1-90-003 (NTIS PB91-125997). May 1990c.

 dc Pcrcin, P.R. Thermal Desorption Attainable Remediation
    Levels.  In:  Proceedings of the 17th Annual Hazardous
    Waste Research Symposium, EPA/600/9-91/002, pp511-
    520. U.S. EPA, Cincinnati, OH. April. 1991 a.

 dc Pcrcin, P.R. Thermal Desorption Technologies. Presented
    at the 84th Annual Meeting of AWMA Paper No. 91 -22.1,
    Vancouver, BC, June 1991b.

 Donnelly, J. Air Pollution Controls for Hazardous Waste
    Incinerators. In: Proceedings of the 12th Annual HMCRI
    Hazardous Materials Control/Superfund 1991 Confer-
    ence. HMCRI, Silver Spring, Maryland. December 1991.

 Eklund, B., D. Green, B. Bl aney, and L. Brown. Assessment of
    Volatile Organic Air Emissions From an Industrial Aer-
    ated Wastewater Treatment Tank. In: Proceedings of the
    14th Annual Hazardous Waste  Research Symposium,
    EPA/600/9-88/021 (NTISPB89-174403).pp468-475.U.S.
    EPA. July 1988.

 Eklund, et al. 1989. Air/Superfund National Technical Guid-
    ance Study Series, Volume HI: Estimation of Air Emis-
    sions from Cleanup Activities at Superfund Sites. Report
    No. EPA-450/1-89-003. U.S. EPA, Research Triangle
    Park, NC, 1989.

 Eklund, B., C. Petrinec, D. Ranum, and L. Hewlett. Database
    of Emission Rate Measurement Projects. EPA 450/11 -91 -
    003 (NTIS PB91-222059LDL). U.S. EPA, RTF, NC. June
    1991a.

 Eklund, B., S. Smith, and M. Hunt. Estimation Procedures For
    AirStrippingof Contaminated Water.EPA-450/1-91-002
    (NTIS PB91-211888). U.S. EPA, Research Triangle Park,
    NC. May 1991b (revised August 1991).

 Eklund, B., S. Smith, and A. Hendler. Estimation of Air
    Impacts For the Excavation of Contaminated Soil. EPA-
    450/1-92-004 (NTIS PB92-171925). U.S. EPA, Research
    Triangle Park, NC March 1992a.

 Eklund, B., S. Smith, P. Thompson, and A. Malik. Estimation
    of Air Impacts For Soil Vapor Extraction (SVE) Systems
    EPA-450/1-92-001 (NTIS PB92-143676). U.S. EPA,
    Research Triangle Park, NC. January 1992b.

Eklund, B., P. Thompson, W. Dulaney, and A. Inglis. Air
    Emissions From the Treatment of Soil Contaminated with
    Petroleum Fuels and Other  Substances. EPA-Control
    Technology Center. EPA-600/R-92-124. July 1992.
 Helsel, R.W. and R.W. Thomas,, Thermal Desorption/Ultra-
    violet Photolysis Process Technology Research, Test, and
    Evaluation Performed at the Naval Construction Battalion
    Center, Gulfport, MS. For the US AF Installation Program
    Volumes I and IV. AFESC, Tyndall Air Force Base,
    Florida. Report No. ESL-TR-87-28. December 1987.

 International Technology Corporation. Screening Procedures
    For Estimating the Air Impacts of Incineration at Super-
    fund Sites. EPA-450/1-92-003 (NTIS PB92-171917).
    February 1992.

 Johnson, et al. A Practical Approach to the Design, Operation,
    and Monitoring of In Situ Soil-Venting Systems. Ground
    Water Monitoring Review. Spring 1990.

 Lighty, J.S., G.D. Silcox, D.W. Pershing, V.A. Cundy, and
    D.G. Linz. Fundamentals for the Thermal Remediation of
    Contaminated Soils. Particle and Bed Desorption Models.
    ES&T Vol. 24, No. 5, pp750-757, May 1990.
                             * ; •
 Oppelt, E.T. Incineration of Hazardous Waste - A Critical
    Review. JAPCA, Vol. 37, No. 5, pp558-586, May 1987.

 Pedersen, T.A. and J.T.  Curtis. Handbook of Soil Vapor
    Extraction Technology. EPA/540/2-91/003 (NTIS PB91 -
    168476). February 1991.

 PES Corp. Soil Vapor Extraction VOC Control Technology
    Assessment. EPA-450/4-89-017 (NTIS PB90-216995).
    U.S. EPA, Research Triangle Park, NC, September 1989.

 Ponder, T. and D. Schmitt. Field Assessment of Air Emissions
    From Hazardous Waste Stabilization Operations. In: Pro-
    ceedings of the 17th Annual Hazardous Waste Research
    Symposium. EPA/600/9-88/021 (NTIS PB91-233627).
    July 1988.

 Thompson, P., A. Inglis, and B. Eklund. Emission Factors for
    Superfund  Remediation Technologies. EPA-450/1-91-
    002 (NTIS PB91-19075). March 1991.

 Troxler, W.L.,  J.J. Cudahy, R.P. Zink, and S.I. Rosenthal.
    Thermal Desorption Guidance Document for Treating
    Petroleum Contaminated Soils. EPA Contract No. 68-C9-
    0033. Report to James Yezzi, U.S. EPA, Edison, N.J.

U.S. EPA. HAZCON Solidification Process, Douglassville,
    PA - Applications Analysis Report. EPA/540/A5-89/001.
    U.S. EPA,  Cincinnati, OH. May 1989a.

U.S. EPA. Hazardous Waste Treatment, Storage, and Disposal
    Facilities (TSDF) — Air Emission Models. Report No.
    EPA-450/3-87-026 (NTIS PB88-198619).  U.S. EPA,
    Research Triangle Park, NC, November 1989b.

U.S. EPA. Engineering Bulletin - Mobile/Transportable Incin-
    eration  Treatment. EPA/540/2-90/014,  (NTIS PB91-
    228023). September 1990a.
                                                    34

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U.S. EPA. 40 CFR Part 264.343. Federal Register 55, No. 82,
    April 27,1990b.

U.S. EPA. International Waste Technologies/Geo-Con In Situ
    Stabilization/Solidification - Applications Analysis Re-
    port. EPA/540/A5-89/004. U.S. EPA, Cincinnati, OH.
    August 1990d.

U.S. EPA. Engineering Bulletin - Slurry Biodegradation. EPA/
    540/2-90/016 (NTIS PB91-228049). September 1990e.

U.S. EPA. Engineering Bulletin  - Soil Washing Treatment.
    EPA/540/2-90/017 (NTIS  PB91-228056). September
    1990f.

U.S. EPA. Engineering Bulletin - Solvent Extraction Treat-
    ment. EPA/540/2-90/013 (NTIS PB91-228015). Septem-
    ber 1990g.

U.S. EPA. Handbook on In Situ Treatment of Hazardous.
    Waste-Contaminated Soils.  EPA/540/2-90/002 (NTIS
    PB90-155607). U.S. EPA,  Cincinnati, OH. September
    1990h.
U.S. EPA. Survey of Materials - Handling Technologies Used
    at Hazardous Waste Sites. EPA/540/2-91/010. U.S. EPA-
    ORD, Washington, B.C. June 1991a.

U.S. EPA. Toxic Treatments, In-Situ Steam/Hot-Air Stripping
    Technology - Applications Analysis Report. EPA/540/
    A5-90/008. U.S. EPA, Cincinnati, OH. March 1991b.

U.S. EPA. The Superfund Innovative Technology Evaluation
    Program: Technology Profiles Fourth Edition. EPA/540/
    5-91/008. U.S. EPA, Cincinnati, OH. November 1991c.

Vancit, M.A., et al. Air Stripping of Contaminated Water
    Sources - Air Emissions and Controls. EPA-450/3-87-017
    (NTIS PB88-106166). August 1987.

Weitzman,L., et al. Volatile Emissions From Stabilized Waste.
    In: Proceedings of the Fifteenth Annual Research Sympo-
    sium. EPA-600/9-90/006 (NTIS PB91-145524). Febru-
    ary 1990.
                                                     35

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                                                  Chapter 5
                            Point Source Controls for VOCs and SVOCs
  Information about various control technologies whose pri-
mary use is to control air emissions of volatile organic com-
pounds (VOCs) and semi-volatile organic compounds (SVOCs)
is presented in this chapter. Control technologies addressed in
this chapter are carbon adsorption, thermal oxidation, catalytic
oxidation, condensers, internal combustion engines, biofilters,
operational controls, membranes, and emerging technologies
such as ultraviolet treatment. The discussion for each control
technology includes a process description, applicability for re-
mediation technologies, range of effectiveness, sizing criteria,
and cost information.

5.1     Carbon Adsorption
5.1.1   Process Description
  Carbon adsorption systems (CAS) are one of the most com-
monly  used air pollution control devices for the reduction of
VOC emissions from remediation processes. They are effective
in removing a wide range of VOCs over concentrations from low
ppbv to about 1,000 ppmv. The most common form of carbon
used in CAS is granular activated carbon (GAC), though other
adsorbents such as impregnated carbon, silica gel, or activated
alumina may be used also. These alternate adsorbents typically
cost more than GAC, but are more effective for certain corrosive
gases or pollutants that do not have ahigh affinity for pure carbon
(e.g., mercury, nickel, phosgene, or amines).

  The physical principle behind any adsorption process is the
Van der Walls attractive potential between the waste  stream
constituents and the GAC in the bed. The potential energy is
given off as heat during adsorption. Since adsorption efficiency
is an inverse function of temperature, the stream must be kept
relatively cool. If the carbon is to be regenerated, then heat must
be added to overcome the Van der Walls force, thus freeing the
pollutants. The carbon then must be cooled prior to re-use, and
the pollutants, once again airborne (or in some liquid solution),
must be disposed of in some acceptable way. If the system is non-
regenerable, then the carbon units themselves must be treated as
solid waste and disposed of accordingly.

  Carbon has a fixed capacity  or number  of active adsorption
sites. As the adsorbing liquid/gas stream  fills the sites in the
adsorbent, a somewhat arbitrary, empirically-determined point
is reached (called the "loading" point) where  adsorption effi-
ciency  is decreased significantly. This is typically around 1 g
VOC per 10 g carbon. If adsorption were continued beyond this
point, then the "break through" point would be reached, and
pollutants would no longer be controlled effectively. Eventually,
"saturation" would be reached, where all sites are filled and
virtually no adsorption occurs.

  A number of CAS designs are commercially available. The
three most common basic designs are canister systems with off-
site regeneration, continuous regenerating systems, and dual bed
systems with on-site batch regeneration as shown in Figures 5-1,
5-2, and 5-3, respectively. The canister system in Figure 5-1
                        Clean gas out
    Carbon
   adsorber
                          VOC off-gas
Figure 5-1. Schematic diagram of canister-based granularactivated
          carbon adsorption system.
                                                        37

-------
Sc
V
\
rVKr
xbent
ipper-
t"f &
' « * *

* '«

'*.*"i Cross-flow /
' 5-»l adsorbent /
                                              Clean
                                               gas
                                               out
       gash
               Thermal
               desorber
             Adsorbent
             feed motor
     Compressed air
Figure 5-2. Schematic diagram of continuously regenerated carbon
          adsorption system.
shows two side-by-side canisters of activated carbon that can be
used sequentially or in parallel. Carbon in 55-gallon drum canis-
ters is available also. In Figure 5-2, a moving-bed system is
illustrated, with  adsorption occurring as the adsorbent falls
through a baffle, while the waste stream passes across the baffle.
The carbon is regenerated on its way back to the top of the baffle.
These systems are used much less commonly than fixed-bed
systems. In Figure 5-3, a standard fixed-bed system is shown,
with two beds adsorbing while the third is desorbing. Regenera-
tion typically is  accomplished by passing steam through the
carbon. The high temperature and water vapor strip most organic
solvents from the carbon and the organics are captured with the
condensed water leaving the system. Subsequent treatment is
necessary to separate the organic fraction from the water before
disposal or use of the solvent. A modification to steam regenera-
tion is to use an inert gas to reactivate the carbon; an additional
step (e.g., condensation) is required to separate the VOCs from
the inert gas.  Such systems are initially more expensive than
steam regeneration systems, but potentially offer savings from
reduced energy use and recovery of purer solvent.

  The major components of a GAG control system include the
pretreatment devices (de-humidifiers, absorbers, particulate fil-
ter, etc.), piping to carry'the stream to the adsorbent,  then the
adsorption bed or canister followed by piping to other add-on
controls or a stack. A regeneration unit is also  present if the
system uses regenerable technology; it can have either multiple-
fixed beds or a moving bed. In the former,  several beds usually
are used in parallel, so that while some are being regenerated,
others are in-line and adsorbing. The moving bed type is less
common and the carbon is regenerated at one point while adsorb-
ing at another.

  The operational cycle for a carbon bed is adsorption, heat
regeneration, drying, and cooling. The heat to regenerate the
carbon must be greater than the heat released during adsorption.
The operational cycle for a carbon canister is adsorption, replace-
             Clean gas out
Clean gas out
   Clean gas out
Clean gas out
                                                                                                           Clean gas out
    Carbon
   adsorber
  voc
 off-gas
Figure 5-3. Schematic diagram of carbon adsorption system with on-site batch regeneration.


                                                          38
                                                                                         Fuel
                                                                     Condensate

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ment at the loading pqint, and, either disposal or removal and
subsequent off-site regeneration.

5.1.2   Applicability to Remediation Technologies
' GAC is a likely candidate for the control for any site remedia-
tion involving a point source having low concentrations of VOCs
emitted to the atmosphere. GAC systems are relatively cheap and
easy to install, they can be either regenerable or disposable, and
they handle many different types of contaminants. As one of the
most widely-used control technologies, much technical informa-
tion is available about these,systems and there are numerous
vendors.          • •  >••.'....•                    •

  For gas streams  with VOC  concentrations exceeding 1,000
ppmv, condensers, incinerators, or internal combustion engines
become competitive in cost-effectiveness with GAC, systems.
GAC systems are also less efficient at higher temperatures or
pressures. Further, they require low humidity in the incoming
stream, since water binds to  the active sites in  the carbon.
Plugging, fouling, and some corrosive gases also pose a problem
for the adsorption  of some waste stream constituents. Any of
these, drawbacks may  be amended with pretreatment devices,
although such pre-treatment usually will increase the total sys-
tem cost.

  The most substantial shortcoming of GAC systems is that, only
compounds with molecular weights in the 50 - 200 g/g-mol range
have the proper adsorption properties. Also, pollutants are not
destroyed, only transferred from one medium to another, inevi-
tably leaving solid or liquid waste after treatment. In industrial
applications, GAC systems often are used to capture and recycle
valuable pure VOCs, but in remediation projects these VOCs
usually are not of sufficient purity or value to warrant recycling.
Disposal is almost always the final step.

  Carbon canisters generally are used for remediation projects
which are quite different from those appropriate for regenerating
beds; cans usually are used for low volume, intermittent sources.
If they are regenerated, it usually is done off-site by the carbon
supplier. One problem that may occur for such systems is that
they may be used past the effective adsorption point of the carbon
and into saturation due to lack  of monitoring and the disposable
nature of canister carbon.

5.1.3    Range of Effectiveness
  An unalterable limitation of adsorption is the molecular weight
of the VOCs to be adsorbed. If the molecular weight of a VO.C is
too low the compound  will  not adsorb very readily.  If the
molecular weight is too high, the compound will be difficult to
desorb from the carbon. This limitation can be circumvented to
some degree by using different types of carbon. A typical range
of effectively adsorbed molecular weights is between 50 and 200
g/g-mol. Other factors, such as polarity and molecular shape,
may also affect adsorptivity.

  A GAC system is most cost-effective when contaminant con-
centrations are low and the waste gas flowrate is low or variable.
Carbon systems also  are not  readily available for flow rates
exceeding 100,000 scfm. A properly operating GAC system at
moderate flow rates and hazardous air pollutant (HAP) concen-
trations (e.g., ppm level) can have a removal rate of 70-99+%,
depending on the pollutant and the  operating temperature. As
with other control devices, higher efficiencies are achieved at the
cost of higher pressure drops across the adsorption unit.

  Pretreatment may ameliorate other limitations of the technol-
ogy. Certain operating conditions should be met: no fouling
compounds (including solid or liquid particulates), less than
1,000 ppmv inorganics, and relative humidity below 50%. The
efficiency of VOC adsorption decreases rapidly as the relative
humidity rises above 50%. The relative humidity of the gas
stream can be lowered by raising the temperature of the gas
stream, but this can affect removal efficiencies. For adsorption to
occur readily, the waste stream must be at a moderate tempera-
ture (100 -  130°F). Outlet VOC concentrations  usually are
required to be less than 10-50 ppmv. The effectiveness of CAS
for various classes of compounds is summarized in Table 5-1.

5.1.4   Sizing Criteria/Application Rates
  GAC systems are capable of handling concentrations from the
ppb level to 25% of the lower explosive limit (LEL). For sizing
a system, the total carbon requirement is the most important
parameter. This will be a function of the volumetric carbon flow
rate, VOC concentration, and VOC molecular weight  of the
waste strea'm, and carbon adsorption capacity, adsorption time,
the removal  efficiency required, and the number of beds. (For
more detailed sizing discussions, see U.S. EPA, 1991 or U.S.
EPA, 1990). For a fixed-bed adsorption system with a specific
adsorption time, t, the following equation may be used (U.S.
EPA, 1991):
   Wc = 2(6.0x10~a) • t • Q • C • -=-
 E_
100
                                    A    .
(Eq.5-1)
  where:

  Wc     =  Weight of carbon required (Ib);
  t       =  Adsorption cycle time, (hr);
  Q      =  Emission stream flow rate (scfm);
  DHAp   =  HAP density (gas)(lb/ft3);
  A      =  Adsorption capacity of carbon bed, (Ib HAP/
              100 Ib carbon);
  C      =  Inlet concentration of HAPs (ppmv);
  E      =  Removal efficiency (%)
  2      =  Factor for a two-bed system;' and
  6.0xlO's   =  Conversion factor
                                        mm
                                     hr-  ppmv
   A typical default value for A is 10. Adsorption capacities for
some HAPs by a commonly-used type of activated carbon are
given in Table 5-2. Adsorption capacities also can be calculated
as a function of inlet concentration, temperature, etc. (see U.S.
EPA, 1990).

5.1.5   Cost Estimating Procedure
   The U.S. EPA has published detailed cost estimation proce-
dures for GAC systems (U.S. EPA, 1990). Only a rough outline
of that discussion is given in this section, and it should only be
                                                         39

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 Tablo 6-1. Applicability of CAS for Selected Contaminants
   Contaminant class
                                            Examples
                                    CAS typically effective?
          Comments
 Aromalics
 Aliphatics
 Halogenated hydrocarbons
 Light Hydrocarbons
   (MW<50orBP<20°C)
 Heavy Hydrocarbons
   (MW > 200 or BP > 200"C)
 Oxygenated compounds
 Certain reactive organics
 Bacteria
 Radioisotopes
 Certain inorganics
 Mercury
           benzene, toluene                  Yes
           hexane, heptane                  Yes
              chloroform                    Yes
            methane, freon                    No

            glycols, phenols                  Noa

          ketones, aldehydes                 Nob
    1,1,1 -trichloroethane, organic acids            No
               coliform                      Yes
                 1311                        Yes
hydrogen sulfide, ammonia, hydrochloric acid       Yes
                 —                        Yes0
Standard application of GAC
Standard application of GAC
Standard application of GAC
Will not adsorb

Will not desorb or will not be
adsorbed due to steric constraints
Fire hazard
Will react with and degrade GAC
Requires silver-impregnated GAC
Requires coconut-shell carbon
Requires impregnated GAC
Requires impregnated GAC
 " Non-rogonorabie caibon systems may work.
 » Not all oxygenated compounds aro a problem.
 * High levels ol sulfur dioxide may "blind1' the charcoal and reduce Hg removal efficiencies.
 used as a preliminary cost-estimating tool. The total costs of a
 GAC system are broken down into three categories:

   1.   Equipment costs, including carbon and containers;

   2.   Installation, engineering, and indirect costs associated
       with purchasing and installing the system; and

   3.   Annual expenses.

   These costs will vary depending on whether canister or beds
 are used, and also whether corrosive or non-corrosive gases are
 present in the waste stream.

 Equipment Costs
   Note: The costs in this section and throughout the document
 have been converted to 1992 dollars, assuming 5% per year
 compounded inflation. The cost for a carbon adsorption system
 is obviously a function of the total carbon requirement as well as
 other factors. However, the cost can be estimated strictly on the
 basis of the carbon,  within some limitations.  Primarily,  this
 approach assumes that  a non-corrosive waste stream is being
 used, so that a less-expensive stainless steel and inexpensive
 carbon may be used. In that case, the following formulae hold
 (Vatavuk, 1990):
 Price (or fixed
 bed regenerate: P = 173 W t848' 350 s W < 14,000 Ib (Eq. 5-2)
 Modular
 adsorbents:      P = 6.24 Wt968' 110  14,000 :£W< 222,000 Ib

                W is the weight of carbon per unit.

Installation Costs
  A general rule for carbon adsorption units is that installation
costs are about 25% of the total unit for a packaged-type device,
                                 or 61 % for a custom built device (Vatavuk, 1988). For the capital
                                 cost factors for any buildings, power, and other general compo-
                                 nents of the carbon adsorption system, refer to Section 5.2.5.

                                 Annual Expenses
                                  The VOC concentrations where GAC systems are cost effec-
                                 tive relative to fume incineration are illustrated in Figure 5-4
                                 (AMCEC, 1991). Systems have a return on investment in two to
                                 three years for industrial applications (AMCEC, 1991). Since
                                 systems have a 10-year average life-span, a salvage value is
                                 likely after a remediation project is completed. The carbon itself
                                 only lasts two years, and the typical cost for carbon is $1.80 to
                                 $2.00 per pound, depending on the total weight purchased (DCI,
                                 1991). Other grades of carbon and impregnated carbons will have
                                 higher costs.

                                  Relatively detailed cost estimating tables also have been devel-
                                 oped (U.S. EPA, 1990). Estimation procedures for annualized
                                 carbon costs for fixed bed carbon adsorbers are given in Table 5-
                                 3.  A cost-effectiveness diagram giving a rough guide for the
                                 applicability of CAS systems for varying vapor concentrations is
                                 presented in Figure 5-5. Non-regenerable systems are compared
                                 with automated and manual regenerable systems in this figure.

                                  Annual costs for canister systems containing 150 Ibs of BPL
                                 carbon are:
                                               Quantity
                                                 1-3
                                                 4-9
                                                10-29
                                                 >30
      Cost, each can
          $920
          $880
          $830
          $780
                                  For the case of waste streams involving corrosive gases, the
                                system costs can be expected to be twice those of a regular system
                                which approximates the increased cost of both the special adsor-
                                bent, as well as all metal work which must be resistant to the
                                corrosive agents.
                                                          40

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Table 5-2.  Reported Operating Capacities for Selected Organic Compounds

        Compound                Average inlet concentration (ppmv)
            Adsorption capacity a (Ib VOC/100 Ib carbon)
Acetone .
Benzene
n-Butyl acetate
n-Butyl alcohol
Carbon tetrachloride
Cyclohexane
Ethyl acetate
Ethyl alcohol
Heptane
Hexane
Isobutyl alcohol
Isopropyl acetate
Isopropyl alcohol '
Methyl acetate
Methyl alcohol
Methylene chloride
Methyl ethyl ketone
Methyl isobutyl ketone
Perchloroethylene
Toluene
Trichloroethylene
Trichlorotriofluoroethane
Xylene
1,000
10
150
100
10
300
400
1,000
500
500
100
250
400
200
200
500
200
100
100
200
100
1 ,000
100
8
— 6
8
8
10
6
8.

8
6
6
8
8
8
7
7
10
8
7
20
7
15
8'
10
 '  Adsorption capacities are based ori 200 scfm of solvent-laden air at 100° F (per hour).

 Source: Marzone and Oakes, 1973.
 5.2     Thermal Oxidation
 5.2.1    Process Description
   Thermal oxidation, also known as thermal incineration, is a
 commonly used approach for controlling volatile organic com-
 pound (VOC) emissions in waste gases. In thermal oxidation,
 contaminant-laden waste gas is heated to a  high temperature
 (above 1000°F) where the VOC contaminants are burned with air
 in the presence of oxygen to form carbon dioxide and water.

   Figure 5-6 is  a simplified schematic of a thermal oxidation
 system. This type of system, which is designed only for handling
 waste gases and not liquids or solids, often is referred to as a fume
 incinerator. The three key design parameters for fume incinera-
 tors are  commonly called the "Three T's": temperature, resi-
 dence time (also referred to as "retention time" or "dwell time")
 and turbulence.  The "Three T's" have an interrelated effect on
 combustion performance. To achieve good combustion, the
 waste gas must be held for a sufficient time (usually 0.3-1.0
 seconds) at combustion temperatures 100°F or more above the
 auto-ignition temperatures of the contaminants in the waste gas.
 Additionally, turbulent flow conditions must be maintained  in
 the incinerator to ensure good mixing and complete combustion
 of the waste contaminants.

   In a typical fume incinerator, waste gas is introduced into the
 combustion chamber as shown in Figure 5-6. In the combustion
 chamber the waste gas temperature is raised to the appropriate
 combustion range by burning auxiliary fuel. Because of the high
 combustion temperatures (1,000  to 1,600°F for most VOCs),
 refractoryrlined chambers are required. At these temperatures,
95 to 99 percent of the VOCs in the waste gas are combusted
(Katari, et al., 1987a).

  In most cases, the  flue gas from the combustor then passes
through a heat exchanger where a portion of its sensible heat is
used to preheat the incoming waste  gas. The flue gas then is
vented to the atmosphere through a stack downstream of the heat
exchanger.

  One way in which fume incineration systems differ from one
another is in the type of heat recovery used. The heat exchanger
design is important because it determines the amount of heat
recovery. In turn, the fraction of heat which can be recovered
from the flue gas will affect directly the amount of fuel required
to operate the incinerator. Typically, two types of heat exchange
systems are used: recuperative heat exchange and regenerative
heat exchange. In a recuperative heat exchanger, hot gas travels
on one side of a partition while cold gas passes on the other. Heat
is transferred directly from the hot side to the cold side through;
the partition. This is the most common type of heat exchanger.
Both counter-flow and cross-flow exchanger designs are used for.
this purpose. For a recuperative exchanger, heat recovery typi-
cally varies from 30-75%.

  In a regenerative heat exchange system, energy is transferred
indirectly from the hot stream to the cold stream. First,  the hot
flue gas is passed through a ceramic matrix to recapture as much
of the energy as possible. The heated ceramic then is used to
preheat the contaminated flue gas, which in turn is run through a
second matrix to recapture its energy before being exhausted to
the atmosphere. Vendors of regenerative systems typically guar-
                                                           41

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             g
             1
             a-
                      40
                      30
S   20
                      10
            I

            II
    -10
                    -20
                                                                                           7	•	1
                                                                         Adsorption/oxidizer
                                                                         Incineration
                                        100
                                                  1
                                                                           L
             Source: Amcec, 1991.
                                                         200             300

                                                       Contaminant concentration (ppmv)
                                                                          400
                                                                                           500
 Figure 5-4. Fuel cost/gain vs. concentration of carbon and incineration systems at 50,000 scfm of solvent-laden air.
 antcc8Q-95%heatrccovery.Asaresultofthehighheatrecovery,
 fuel costs tend to be low compared to traditional thermal incin-
 erators using recuperative gas-gas heat exchange for energy
 recovery. However, because the technology is relatively new,
 equipment and other capital costs tend to be high. For Superfund
 rcmcdiations that are short in duration (e.g., <36 months), the
 high capital and installed costs often make regenerative incinera-
 tion unattractive since the period over which the equipment is
 depreciated is brief. The economics for regenerative thermal
 incineration are most favorable for the treatment of a dilute, large
 volume waste gas, since it would not require large amounts of
 auxiliary fuel. In industrial applications, regenerative thermal
 incineration is commonly used for controlling VOC emissions
 from process point sources such as paint spray booths or solvent
 degreasers.

  An alternative method of heat recovery, which may be practi-
cal in some cases, is to produce low-pressure steam in a waste
heat boiler. This alternative is only used in cases where low
pressure steam is needed at or near the remediation site.

5.2.2   Applicability to Remediation Technologies
  The applicability of thermal incineration depends on the con-
centration of oxygen and contaminants in the waste gas. The
                                             waste gas composition will determine the auxiliary air and fuel
                                             requirements. These requirements in turn will have a strong
                                             influence on whether thermal oxidation is an economical ap-
                                             proach for controlling air emissions.

                                               For most remediation technologies used at Superfund sites, the
                                             off-gases that require control are dilute mixtures of VOCs and air.
                                             The VOC concentration of these gases tends to be very low, while
                                             their oxygen content is very high. In this case auxiliary fuel is
                                             required but no auxiliary air is needed. However, if the waste gas
                                             has a VOC content greater than 25 percent of its LEL (e.g., some
                                             SVE-based clean-ups), auxiliary air must be used to dilute the
                                             contaminant to below 25 percent of its LEL prior to incineration.

                                               If the remediation activity generates an off-gas that has a low
                                             oxygen content (below 13 to 16 percent), ambient air must be
                                             used to raise the oxygen level to ensure the burnerflame stability.
                                             In the rare case when the waste gas is very rich in VOCs, using
                                             it directly as a fuel may be possible.

                                               Information is  presented in Table 5-4 for determining the
                                             suitability of a waste gas for incineration and establishing its
                                             auxiliary fuel and oxygen requirements. This same information
                                             is shown in Figure 5-7 in an alternative format.
                                                         42

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Table 5-3.  Equations for Carbon Adsorption Annualized Cost Estimate
                      Cost item
                                                                                                  Equation
 I.      Direct costs

       a.   Steam costs, Cs
       b.   Cooling water cost,
       c.   Electricity
            1.    Pressure drop, Pb, for regenerative systems
                 (based upon superficial velocity of 60 ft/min)
            2.   Pressure drop, P0, for canister systems



            3.   System fan horsepower, h ^

            4.   Bed cooling/drying fan, h M
             5.   Cooling water horsepower, h
             6.   Required electricity usage per year, kWh

        d.   Carbon replacement cost, CRC
C5=3.5x10-3Mvoc(HRS)Ps

where:     Mvoc   =   Inlet VOC loading, Ibs/hr
           MRS   =   Operating hours per year
           P      =   Steam price, $/103lbs
     =3.43C3Pcw/Pa
                                                                                              Cooling water price, $/103 gal
                                                                                              (assumed to equal $0.225/103 gal)
where:
Pb = tb (2.606)
                                                                        where:     t b     =   Bed thickness, ft. carbon

                                                                                               0.0166Creq a
                                                                                   *b     =       LD~
                                                                                   Creq    =   carbon required
                                                                                   L      =   vessel length
                                                                                   D      =   vessel diameter
 Po  = 0.0471 Qc +9.29x10-" Qg
 where:     Q,.    =    Emission stream flowrate, ft 3/min

 h^ = 2.5x10-"(PborP0+1)Q0

 hdd= 1.86x10 -4(FRdcf)(Pb+ 1) (BM)

 where:      FRdcf =    (^00) (C req) /Q^^o,
            6 M   =    cooling/drying cycle time, hr
            6 d=, .  =    0.4(ereg)(NA)(HRS)/ead
            8 reg   =    regeneration cycle time, hr
            6 ^   =    adsorption cycle time, hr

 li= (2.52 x 10 -"q^,  HS)/n
 where:     qcm     =   Cooling water flowrate, gal/min
            H      =   Required head (usually 100 ft H2O)
            S      =   Specific gravity of fluid
            n      =   Pump and motor efficiency

 kWh = 0.746 (h•„„,+ h ^ ) MRS + h^,

 CRC  =  CRFC(1.08CC + COI)

 where:     CRFC  =   Capital recovery factor for carbon
            C0     =   Carbon cost, $/lb
            COI     =   Replacement labor cost, $/lb
               	(typically about $0.05/lb)   ,	
  a Assumes a two-bed system.

  Source: U.S. EPA, 1991.
                                                                 43

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                  7000
                  6000
                  5000
              •I*  4000
                  3000
                  2000
                  1000
	  Replaceable Cannisters
	  Dual Bed, On-Site Regeneration
	Automatic Regenerate Beds
                               Note: Capital costs amortized over five years.
                                             10          15          20
                                                      VOC Recovery (Ibs/day)
                                                 25
                                                             30
                                                                        35
              Source: U.S. EPA, 1991.

 Figure 5-5. Activated carbon systems cost comparison.
   If halogenated VOCs are present in the influent gas stream,
 then hydrochloric acid (HC1) may be produced in the thermal
 incinerator. HC1 emissions are regulated and off-gas controls
 such as packed-column gas absorbers for HC1 and other acid
 gases may be required.

 533   Range of Effectiveness
   Thermal incineration is a well-established method for control-
 ling VOC emissions in waste gases. The control efficiency (also
 referred to as destruction and removal efficiency or DRE) for
 thermal incineration is typically 98% or higher. Factors which
 affect DRE include the three "T's" (temperature, residence time,
 and turbulence) as well as the lype of contaminants in the waste
 gas. With a 0.75-second residence time, the suggested thermal
 incinerator combustion temperatures for waste gases containing
 nonhalogenated VOCs are 1,6CO°Fand 1,800°F, respectively for
 98 and 99 percent VOC destruction efficiencies. Higher tempera-
 tures (about2,000°F) and longerresidence times (approximately
 1 second) are required for achieving DRE's of 98% or more with
halogenated VOCs (Katari, etal., 1987a, U.S. EPA, 1991).
  In this discussion the term Itowrate implies the flowrate at standard conditions
  wWch aro assumed to be 60BF and 1 aim, following standard engineering
  practices.
                              5.2.4   Sizing Criteria
                                To size a thermal incinerator with a given residence time and
                              estimate the capital and anntialized costs, three pieces of data are
                              required:

                                1)   The flue gas flow rate;-
                                2)   The auxiliary fuel and air requirements;
                                3)   Inlet VOC concentration (or heat content);
                                4)   Inlet temperature; and
                                5)   Combustion temperature.

                              Flue Gas Flowrate
                                For dilute waste gases the flue gas flowrate1 is approximately
                              equal to the waste gas flowrate. In cases where auxiliary air is
                              required, the flue gas flowrate is roughly equal to the sum of the
                              waste gas flowrate and the auxiliary air flowrate. The flue gas
                              flowrate can be used in many correlations to size the incinerator
                              and estimate equipment costs.

                              Auxiliary Fuel Requirement
                               The auxiliary fuel is usually the largest operating expense for
                              a thermal incineration system. The fuel requirement can be
                             estimated by making a  heat balance around  the  incinerator
                             system. The approach described below assumes heat losses to be
                             negligible. In many cases this assumption is not valid and the fuel
                                                         44

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                 Auxiliary air
                 (if required)
    Auxiliary
       fuel
                   Combustion
                     chamber

                  (Refractory-lined
                for temperatures to
                    2000+ °F)
                                             Q
                                          heat loss
                                                                  Flue gas
                                                     Preheated waste gas
                        Waste gas from
                      remediation process
                             Heat
                           exchanger
Flue gas
to stack
Figure 5-6. Schematic of thermal Incineration system with recuperative heat exchanger.
Table 5-4.   Categorization of Waste Gas Streams
   Category
       5

       6
              Waste gas
          Composition
                                                                 VOC
                                                             Heat content
                              Auxiliaries and other requirements
                Mixture of VOC, air, and inert gas      >16%      <25% LEL      <13 Btu/ft3      Auxiliary fuel is required. No auxiliary air
                                                                                              is required.

                Mixture of VOC, air, and inert gas      16%      25-50% LEL    13-26 Btu/ft3     Dilution air is required to lower the heat
                                                                                              content to <13 Btu/ft3. (Alternative to
                                                                                              dilution air is installation of LEL
                                                                                              monitors.)
                Mixture of VOC, air and inert gas      <16%
Mixture of VOC and inert gas        0-neglibible


Mixture of VOC and inert gas        0-neglibible

Mixture of VOC and inert gas        0-neglibible
—              —  .        Treat this waste stream the same as
                            categories 1 and 2, except augment the
                            portions of the waste gas used for fuel
                            burning with outside air to bring its O2
                            content to above 16%.

—         <100 Btu/scf      Oxidize it directly with a sufficient a
                            mount of air.

—         >100 Btu/scf      Premix and use it as a fuel.

—    Insufficient to raise gas  Auxiliary fuel and combustion air for
      temperature to the      both the waste gas VOC  and fuel are
      combustion            required.
      temperature
 Source: Adapted from Katari, et al., 1987a.
                                                                 45

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              Dilute
            waste gas
               to
            25% LEL
       Incinerate, but must
        use LEL controls
          and monitors
          CATEGORY 3
          Auxiliary air
           is required
         CATEGORY2
                                         YES
                                    No auxiliary
                                   air Is required
                                  CATEGORY 13
     i  UEL -  Upper Explosive Limit
     2  LEL  -  Lower Explosive Limit
     3  The majority of waste gases generated during Superfund
        remediations fall into Category 1.

     Source: Adapted from V. Katari, et al., 1987a.
                                                                            Inappropriate for
                                                                              incineration.
                                                                           Disposition depends
                                                                            on composition.
                                                                           (Not covered in this
                                                                                section.)
                                                                           Could be explosion
                                                                           hazard depending
                                                                             on O2 content.
                          Hazardous, should
                         not be encountered.
                        For majority of VOCs,
                         waste gas is outside
                        the flammability limits
                             if 02 <10%.
                             Do not use
                            incineration.
                        Use as fuel or premix
                         with additional fuel.


                           CATEGORY5
Auxiliary air may
 be required for
  incineration.
 Auxiliary fuel
is required for
 incineration.
CATEGORY 6
                                                                                                     No auxiliary fuel is
                                                                                                        required for
                                                                                                       incineration.
                                                                                                       CATEGORY 4
Figure 5-7.  Flow chart for categorization of a waste gas to determine Its suitability for Incineration and need for auxiliary fuel and air.


                                                           46

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requirements may be 10% higher to account for heat losses. The
heat balance requires the following data:

  1)  The waste gas and flue gas flowrates (Ib-mol/hr);

  2)  The incinerator combustion temperature (typically 1,600-
      2,000°F);

  3)  The waste gas temperature as it comes from the remedia-
      tion system before it goes through a heat exchanger;

  4)  The concentration of VOCs in the waste gas;

  5)  The approximate heat capacity of the flue gas (Btu/lb-
      mol/°F); and

  6)  The fraction of the total heat release which is recovered in
      the heat exchange system.

  Figure 5-8 shows a simple heat balance around an incinerator
system. From the heat balance the fuel requirement (in MMBtu/
hr) can be estimated as shown below:
                       d-TlV(Qscns-Qrcl)
                           (Eq.5-5)
  where:
        Qfuc,
        T|
Fuel heat required, MM Btu/hr;
Fraction of heat recovered in the heat
exchanger;2
Total sensible heat required to bring
waste gas and auxiliary air to combus-
tion temperature, MMBtu/hr; and
Heat release from complete oxidation
of VOCs in the waste  gas stream,
MMBtu/hr.
  Equations 5-6 and 5-7 can be used to estimate the terms
required for Equation 5-5. Qscns is calculated as indicated below:
   where:
         m
         Cp
          comb
          amb
                                                  (Eq.5-6)
Total sensible heat required to the bring
waste gas and auxiliary air to combus-
tion temperatures, MM Btu/hr;
Mass of flue gas (waste gas plus auxil-
iary air), Ibmol/hr,
Heat capacity of gas, Btu/lbmol/0F3;
Combustion temperature, °F; for non-
halogenated volatiles, default tempera-
ture is 1,600°F; for halogenated vola-
tiles use 2,000°F; and
Ambient air temperature, °F.
 2  For recuperative heat exchange, T| is typically 0.35-0.70. For regenerative
   heat exchange, T) may be as high as 0.80-0.92.

 3  A rough estimate for Cp is to use the Cp of air which is approximately 6.91
   Btu/lb-mol/°F.
                                       Qrel, which is the heat release from combusting the VOCs in the
                                       waste gas, can be estimated as follows:
m-C.
                               H  ./10s
                                 comb
                                                                                        (Eq.5-7)
                                                                                        v  T    /
                                         where:
        m
          H
        106
                                                             Heat release from complete oxidation
                                                             of VOCs in waste gas stream, MM Btu/
                                                             hr,
                                                             Flowrate of flue gas (waste gas plus
                                                             auxiliary air), Ibmol/hr;
                                                             Concentration of VOCs, ppmv;
                                                             Heat of combustion of VOCs in the
                                                             waste gas, MM Btu/lbmol.4; and
                                                             Conversion Factor (ppmv).
                                       Table 5-5.  Typical Pressure Drops a-b for an Incineration System
                                             Equipment type
                                   Pressure drop
                                      (in. H20)
Thermal incinerator
Heat exchanger 35% efficiency
Heat exchanger 50% efficiency
Heat exchanger 70% efficiency
                   4"
                   4"
                   8"
                  '15"
  Total system pressure drop equals the sum of pressure drops across all
  pieces of equipment in the system.
  This table is taken from V. Katari, et al., 1987a.
System Pressure Drop
  The total pressure drop for an incinerator depends on the type
of equipment included in the system as well as other design
considerations. The total pressure drop across  an incinerator
system determines the waste gas fan size and horsepower re-
quirements, which in turn determine the fan capital cost and
electricity consumption (Katari, et al., 1987a).

  An accurate estimate of system pressure drop would require
complex calculations. A preliminary estimate can be made using
the approximate values listed in Table 5-5. The system pressure
drop is the sum of the pressure drops across the incinerator and
the heat exchanger plus the pressure drop through the duct work.

  The pressure drop can then be used  to estimate the power
requirement for the waste, gas fan using the empirical correlation
given below (U.S. EPA, 1990):
             Power =1.17-10-4-V'  P/e
                            (Eq.5-8)
                                                                where:
        Power   =     Fan power requirement, kW-hr;
        V       =     Waste gas flowrate, scfm;
         P       =»     System pressure drop, inches of water
                       column; and
        e        =    Combinedmotorfanefficiency.dimen-
                       sionless (approximately 60%).
                                         A rough estimate for  H ^ is to use the heat of combustion of benzene which
                                         is approximately 1.42 MMBtu/lb-mol. Values for Ho for various VOCs are also
                                         available in standard chemical engineering reference books.
                                                           47

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                    Heat in
              Heat from auxiliary fuel
                     Ore.
             Heat from combustion of
               VOCs In waste gas
Incinerator system
                                                                                                   Heat out
          Qsens
   Heat required to raise
waste gas temperature from
      100°Fto700°F
                                             I
                                                              w recovery
                                                   Heat recovered in heat exchanger
                                            recovery = TlQams, where 11= efficiency of heat exchanger)
 Figure 5-8. Incinerator heat balance.
                 1000
                                      No HE
                                     35% HE
                                     50% HE
                                     70% HE
                                                   10               20
                                                      Volume Flow Rate (1000 scfm)
                      Source: Adapted from V. Katari, et al., 19875.
Figure 5-9. Thermal Incinerator equipment cost estimates.
 (Source: Adapted from V. Katari, et al., 1987b.)
                                                             48

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5.2.5   Cost Estimating Procedure
  The process of estimating capital and annual expenses for an
incineration system can be divided into three parts. Estimates
must be made for the following:

  1)  Equipment costs including incinerator, stack, and con-
      trols;

  2)  Installation, engineering, and indirect costs  associated
      with purchasing and installing the control equipment; and

  3)  Direct and indirect annual expenses.

Equipment Costs
  A typical incinerator system may include the following com-
ponents:  (1) a waste gas fan;  (2) a refractory chamber with
burner; (3) heat recovery equipment; (4) controls, instrumenta-
tion, and control  panel; and  (5) a stack. In addition, other
equipment such as ductwork may be required to integrate the
incinerator with the remediation process. The equipment costs
for an incineration system generally can be estimated two ways:
 1) by obtaining quotations from vendors, or 2) by using general-
ized cost correlations available in the literature.

   The purchased cost of a typical incinerator system will vary
 widely depending on several design factors. Consequently, cau-
 tion is required when using generalized costcorrelations. Among
 the factors that influence the purchased cost of a thermal incin-
 eration system are the supplier's design experience, materials of
 construction, instrumentation, the type of heat exchanger used,
 and the nature of the installation (i.e., Do any factors exist that
 make installing the equipment unusually difficult?)

   Thermal incinerator equipment costs are presented in Figure 5-
 9 as a function of flue gas flowrate at standard conditions of 60°
 and 1 atm (absolute). This figure is adapted from an article by
 Katari, et al., 1987b which used cost information from incinerator
 manufacturers to develop costcorrelations. The equipment costs
 given represent the cost for  a complete incineration system
 including acombustion chamber with burner, waste gas fan, inlet
 and outlet plenums, prepiping, prewiring, instrumentation and
 controls, a 10-ft stack, and in the case of heat recovery, a primary
 heat exchanger. Additional cost information is  available in
 Vatavuk,  1990 and U.S..EPA, 1990. Cost estimates for systems
 to treat less than 500 scfm should be obtained directly  from
 vendors.

 Installation, Engineering, and Indirect Costs
    The total capital investment (TCI — equipment costs plus
 installation, engineering, and indirect costs) for an incineration
 system can vary widely as a function of the total equipment cost.
 The TCI for a small skid-mounted unit to be placed at a preprepared
 site may be only 150-200% of the equipment cost. On the other
 hand, for a custom installation requiring extensive site-work
 (e.g., a typical Superfund site), the TCI may run as high as 300-
  400% of the purchased equipment cost.

    One method for generating an estimate of installation, engi-
  neering, and indirect costs is to use the factor approach presented
  in Table 5-6 (Katari, et al., 1987b). Based on the approach given
in this table, the TCI is approximately 160% of equipment costs,
plus any costs for site preparation and construction.

Annual Expenses
  Annual costs for incinerators can be estimated from factors
given in Table 5-7. Determining these expenses requires an
extensive amount of site-specific data. Fuel costs are typically the
major direct annual cost. The system capital recovery is typically
the largest indirect expense. Additional costs may be incurred
due to monitoring requirements and permit activities.

5.3    Catalytic Oxidation
5.3.1   Process Description
  Catalytic oxidation (also known as catalytic incineration) is a
commonly applied combustion technology for controlling VOC
emissions in waste gases. In catalytic oxidation a contaminant-
laden waste gas is heated with auxiliary fuel to between 600 and
900°F. The waste gas is then passed across a catalyst where the
VOC contaminants react with oxygen to form carbon dioxide and
water.

  Except for  the addition of  a noble or base metal catalyst,
catalytic oxidizers are similar  to thermal oxidation systems in
their basic design and operation (see Section 5.2). For catalytic
oxidation, the "Three T's" (temperature, residence time, and
 turbulence) are also important  design variables. In addition, the
 catalyst type has significant effect on the system performance
 and cost.

   A typical catalytic oxidation system is shown in Figure 5-10.
 As the figure shows, the waste gas stream is usually first passed
 through a primary heat exchanger to recover heat  from the
 exhaust gases. Additional heat is then added to the waste gas by
 a natural-gas-fired or electric preheater. From the preheater the
 waste gas then passes into the  catalyst bed.

   The catalyst bed (or matrix) is generally a metal-mesh mat,
 ceramic honeycomb, or other ceramic matrix structure designed
 to maximize catalyst surface area. Catalysts may also be in the
 form of spheres or pellets which may operate in either a fixed-bed
 or fluidized-bed configuration. It is important that the preheat
 temperature not be too high regardless of the type of catalyst. The
 preheat temperature and the temperature rise across the catalyst
 due to combustion must not  produce temperatures which are
 outside the recommended operating range for the catalyst. This
 could cause the catalyst bed to lose activity.

    Downstream of the catalyst bed the hot exhaust gas passes
  through a heat exchanger where it gives up heat to the inlet gas
  streams. In a catalytic oxidation system recuperative heat ex-
  change is used. Catalytic systems using regenerative heat ex-
  change are in the  developmental stage. In some systems a
  secondary heat recovery system such as a waste heat boiler may
  also be used.

  5.3.2    Applicability to Remediation Technologies
    The applicability of catalytic oxidation depends primarily on
  waste gas composition. As described in the preceding section on
  thermal incineration, waste gas composition will determine the
                                                           .49

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  Tabla 5-6.  Cost Factors for Thermal Incinerator Capital Costs
                                       Cost Item
                                                                                     Cost factor (fraction of indicated cost)
  Purchased equipment
       Incinerator and auxiliary equipment
       Instrumentation and controls.
       Taxes
       Freight
  Installation
      Foundations and supports
      Erection and handling
      Electrical
      Piping
      Painting
      Insulation
      Site preparation
      Building/construction
 Engineering and supervision
 Construction/field expenses
 Construction fee
 Start-up
 Performance test
 Contingency
                                                               Direct costs
                                                              Total equipment costs (TEC):
                                                  A
                                             0.10 A
                                             0.03 A
                                             0.05 A
                                                             Total Installation Costs (TIC):
                                                           Total Direct Cost (TEC + TIC):

                                                             Indirect costs
                                                                                                                      B = 1.18A
                                             0.08 B
                                             0.14 B
                                             0.04 B
                                             0.02 B
                                             0.01 B
                                             0.01 B
                                                SP
                                               Bldg
                                 0.30 B + SP + Bldg
                                 1.30B
                                                             Total Indirect Costs:
                                                          Total Capital Investment
                                            0.10 B
                                            0.05 B
                                            0.1 OB
                                            0.02 B
                                            0.01 B
                                            0.03 B
                                            0.21 B
                                                                                                             1.61 B + SP + Bldg
      e! V. Katrf, et al.. 1987b.
                      Auxiliary air
                      (if required)
               Waste gas from
    Q        remediation process
Heat loss
                                                               Catalyst bed

                                                     Preheated waste gas
                                                                                                                      Flue gas
                                                                                                                      to stack
Figure 5-10.   Schematic of cataljrtio oxidation system with recuperative heat exchanger.
                                                                50

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Table 5-7.  Cost Factors for Thermal Incinerator Annual Costs •
                  Itemized expenditures
                                                                                Cost factor
                                                         Direct costs
Labor
     Operating labor
     Supervision
     Maintenance

Maintenance materials.

Utilities
     Electricity
   •  Fuel
 Overhead

 Administrative charges

 Property tax

 Insurance

 Capital recovery
                      0.5 h/shift
                      15% of operating labor
                      0.5 h/shift

                      100% of maintenance labor
                      See note b
                      See note c
                                                         Indirect costs
60% of sum of operating, supervisory, maintenance labor and
                maintenance materials

                      2% x TCI

                      1%xTCI

                      1%xTCI

                CRF x TCI (see note d)
                                                  power requirement the annua, operating hours and .the per kV^hr cost of electrify.
                          Annual Electricity Cost = Power Requirement (kW) • Operating Hours (hrs) • Electricity Cost ($/kW-hr)
 c Annual fuel costs can be estimated using the system fuel requirement, the operating hours, and the per MM Btu cost of Juel.
                            Annual Fuel Cost = Fuel Requirement (MMBtu/hr) • Operating hours (Hrs) • Fuel Cost ($/MMBtu)
 d The capital recovery factor is a function of the equipment life (typically about 10 years) and the interest rate.
 auxiliary air and fuel requirements for combustion controls.
 These requirements in turn will have strong influence on whether
 catalytic oxidation is an economical approach for controlling air
 emissions. The waste gas composition is also important in that for
 catalytic oxidation to be effective the waste gas cannot contain
 catalyst poisons which would limit system performance.

    A table and a flow chart for determining the suitability of a
 waste gas for catalytic oxidation and establishing its auxiliary
 fuel and oxygen requirements were presented in Section 5.2.2 for
 thermal oxidation; this same information is  applicable to cata-
 lytic oxidation. While catalytic oxidation has traditionally not
 been widely used to control halogenated hydrocarbons, im-
 proved catalysts make this application more feasible (Kittrell, et
 al., 1991).

    Table 5-8 presents a list of poisons/inhibitors which can
 significantly degrade the catalyst activity. The presence of any of
 these species in  the waste  gas stream would make catalytic
 incineration unfavorable.

    If halogenated VOCs are present in the influent gas stream,
  then hydrochloric acid (HC1) may be produced in the catalytic
  oxidizer. HC1 emissions are regulated and off-gas controls for
  HC1 and other acid gases may be required.
         Table 5-8.  Common Catalyst Poisons
                                     Sulfur
                                    Chlorine
                                  Chloride salts
                          Heavy metals (e.g., lead, arsenic)
                                Particulate matter
         5.3 3   Range of Effectiveness
            Catalytic oxidation is a well-established method for control-
         ling VOC emissions in waste gases. The control efficiency (also
         referred to as destruction efficiency or DE) for catalytic oxidation
         is typically 90-95 percent. In some cases the efficiency can be
         significantly lower, particularly when the waste stream being
         controlled contains halogenated VOCs.

            Factors which affect the performance of a catalytic oxidation
         system include the following:
            1)   Operating temperature;
            2)   Space velocity (the reciprocal of residence time);5
            3)   VOC composition and concentration;
            4)   Catalyst properties;
                                                                      Space velocity is defined as the volumetric flowrate of the flue gas entering
                                                                      the catalyst bed divided by the volume of the catalyst bed. Space velocity is
                                                                      the inverse of residence time and for a fixed bed catalytic oxidizer is in the
                                                                      range of 30,000-100,000 hr1.
                                                                51

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    5)  Presence of poisons/inhibitors in the waste gas stream-
        and                                               '
    6)  Surface area of the catalyst.

    The operating temperature of a catalytic incineration system is
  dependent on the concentrati on and composition of the VOCs in
  the waste gas stream as well as the type of catalyst used. In most
  cases, the temperature at the inlet of the catalyst bed is at least
  600°F while the temperature atthe outlet is less than 1200°F. The
  temperature, together with catalyst space velocity, has signifi-
  cant affect on system performance. At a given space velocity,
  increasing the operating temperature at the inlet of the catalyst
  bed increases the destruction efficiency. At a given operating
  temperature,decreasingspacevelocity(i.e.,increasingresidence
  time in the catalyst bed), increases destruction efficiency. How-
  ever, as is the case with thermal incinerators, it is not possible to
  predict beforehand the exact temperature and residence time
  needed to obtain a given DRE for a VOC mixture. Rough
  estimates can be made using simple models (Cooper and Alley,
  1986). For example, temperatures reported for 80% DRE of
  1,1,1 -trichlorethane vary from 382°F to 661 °F depending on the
  catalyst used.

  _ The influence of temperature and space velocity on the effec-
  tiveness of a catalytic oxidation system are shown in Figures 5-
  11 and 5-12, respectively. The data shown in these figures are for
  a fluidized-bed catalytic oxidation system. The waste gas treated
  by this unit contained 10-200 ppmv of mixed VOCs, including
 aliphatic, aromatic, and halogenated compounds.

   In designing a catalytic oxidation system temperature and
 space velocity are not the only variables which must be consid-
 ered. The waste gas composition and catalyst type must be
 evaluated simultaneously since the type of catalyst chosen for a
 systemplaces practical limits on the types of compounds thatcan
 be treated. For example, waste gases containing chlorine and
 sulfur can deactivate noble metal catalysts  such as platinum.
 However, chlorinated VOCs  can be  treated by certain metal
 oxide catalysts.

  The control efficiencies of some common VOC contaminants
 are shown in Table 5-9 at two different operating temperatures
 for the fluidized bed catalytic combustor discussed previously.
 As the data show, the destruction efficiency of a catalytic oxida-
 tion systcmcan vary greatly for different contaminant types. The
 lowest destruction efficiencies typically are seen for chlorinated
 compounds.


5.3.4   Sizing Criteria
  To size a catalytic oxidizer correctly and estimate the capital
and annualizcd costs, three pieces of data are required:

  1)  The flue gas flow rate;
  2)  The auxiliary fuel and air requirements; and
  3)  The pressure drop across the system and  waste gas fan
      powerrequirements.
  Table 5-9.  Destruction Efficiencies of Common  VOC Contami-
            nants in a Fluidized Bed Combustor

Cyclohexane
Ethylbenzene
Pentane
Vinyl chloride
Dichloroethylene
Trichloroethylene
Dichloroethane
Trichloroethane
Tetrachloroethylene
Destruction
efficiency at
650° F
mean
99
98
96
93
85
83
81
79
52
Destruction
efficiency at
950° F
mean
99+
99+
99+
99
98
98
99
99
92
 Flue Gas Flowrate
   For dilute waste gases the flue gas flowrate6 is approximately
 equal to the waste gas flowrate. In cases where auxiliary air is
 required, the flue gas flowrate is roughly equal to the sum of the
 waste gas flowrate and the auxiliary air flowrate. For catalytic
 oxidation systems, the flue gas flowrate can be used in many
 correlations to size the catalyst and the overall system.

 Auxiliary Fuel Requirement
   The auxiliary fuel required for a catalytic oxidizer is signifi-
 cantly less than for a thermal incineration unit. In many cases
 auxiliary fuel requirements will be minimal for catalytic oxida-
 tion systems. However, the process of estimating fuel require-
 ments is the same for both catalytic and thermal systems.

  As described in  Section 5.2.4, the fuel requirement can be
 estimated by making a rough heat balance around the oxidation
 system. The approach described below assumes heat losses to be
 negligible. In many cases this is not a valid assumption and the
fuel requirements will be significantly higher than calculated by
this simple approach. The heat balance requires the following
data:
  1)
  2)

  3)

  4)
  5)

  6)
       The waste gas and flue gas flowrates (Ibmol/hr);
       The average temperature across the catalyst bed (700-
       900°F);
       The waste gas temperature as it comes from the remedia-
       tion system before it goes through a heat exchanger;
       The concentration of VOCs in the waste gas;
       The approximate heat capacity of the flue gas (Btu/lbmol/
       °F); and
       The fraction of the total heat release which is recovered in
       the heat exchange system.

  A simple heat balance  around a catalytic oxidation system is
shown inFigure5-13.Fromtheheatbalance the fuel requirement
(in MMBtu/hr) can be estimated using the equations shown for
thermal oxidation in Section 5.2.4.
                                                              In this discussion the term flowrate implies the flowrate at standard conditions
                                                              which are assumed to be 60°F and 1 atm, following standard engineering
                                                        52

-------
         100
          95
      t  90
      o
o
i
c
o
I
       OJ
          85
          80
          75
          70
                                                                                         	  Mixture 1
                                                                                         •  -— Mixture 2
                                                                                       	Mixtures
                                                                                       -	Mixture 4

                                                     Notes
                                                     CombUstor:
                                                     Mixture 1:
                                                     Mixture 2:

                                                     Mixture 3:
                                                     Mixture 4:
         Fluidized bed catalytic oxidizer
         Trichloroethylene/1,2-dichloroethylene
         Trichloroethylene/benzene/ethylbenzene/
         pentane/cyclohexane
         Vinyl chloride/trichloroethylene
         1,2-dichlorpethane/trichloroethylene/
         1,1,2-trichloroethane/tetrachloroethylene
                                                                              _L
                                                                                  _L
                                    _L
              600
                        650
                                   700
                                              750
                                                  800
                                                                   850
                                                                       900
                                                                                        950
                                                                                            1000  '
                                                                                                             1050
                                                    Catalyst inlet temperature (°F)
Figure 5-11. Effect of temperature on destruction efficiency for catalytic oxidation at 10,500 hr -1 space velocity.
System Pressure Drop
  The total pressure drop for an catalytic oxidizer depends on the
type of equipment included in the system as well as other design
considerations. The total pressure drop required across a catalytic
oxidation system determines the waste gas fan size and horse-
power requirements, which in turn determine the fan capital cost
and electricity consumption (Katari, et al., 1987a).

  An accurate estimate of system pressure drop would require
complex calculations. A preliminary estimate can be made using
the approximate values listed in Table 5-10. The system pressure
drop is the sum of the pressure drops across the oxidizer and the
heat exchanger.

  As for thermal oxidation, the pressure drop can then be used to
estimate the power requirement for the waste gas fan using the
empirical correlation given below (U.S. EPA, 1990):
                 Power = 1.17  • 10"» • V- AP/e       (Eq. 5-9)
   where:
         Power
         V
           =   Fan power requirement, kW-hr;
           =   Waste gas flowrate, scfm7;
                                                                 AP      =   System pressure drop, inches of water
                                                                              column; and
                                                                 £        =   Combined motor fan efficiency, dimen-
                                                                              sionless (approximately 60%).
                                                         5.3.5   Cost Estimating Procedure
                                                           The process of estimating capital and annual expenses for a
                                                         catalytic oxidizer can be divided into three parts. Estimates must
                                                         be made for the following:

                                                           1)  Equipment costs including combustor, catalyst, stack, and
                                                               'controls;
                                                           2)  Installation, engineering, and indirect costs associated
                                                               with purchasing and installing the control equipment; and
                                                           3)  Direct and indirect annual expenses.


                                                          Table 5-10. Typical Pressure  Drops a'b for a Catalytic Oxidation
                                                                    System
                                                                  Equipment type             Pressure drop (in. H2O)
Catalytic oxidizer
Heat exchanger 35% efficiency
Heat exchanger 50% efficiency
Heat exchanger 70% efficiency
6"
4"
8"
15"
   1 Ib-mol at 60° F and 1 atm equals 379 scfm.
                                                                  Total system pressure drop equals the sum of pressure drops across all
                                                                  pieces of equipment in the system.
                                                                  This table is taken from V. Katari, et al., 1987a.
                                                             53

-------
            100
             95
       rs-     90
             85
            80
            75
            70
            65
 Notes
 Combustor:    Fluldized bed catalytic oxidizer
 Mixture 1:      Trichloroethylene/1,2-dichloroethylene '
 Mixture 2:      Trichloroethylene/benzene/ethylbenzene/
              pentane/cyclohexane
 Mixtures:      Vinyl chloride/trichlorqethylene
 Mixture 4:      1,2-dichIoroethane/trichloroethylene/
	1,1,2-trichloroethane/tetrachloroethylene
     JL
                                      1 - 1 - 1 - . _ '     •     '
                                                          _L
               6500       7030      7500      8000       8500      9000       9500

                                                         Space velocity (hr -1)

Figure 5-12. Effect of space velocity on destruction efficiency for catalytic oxidation at 720° F.
                                                                   10000
                                                                              10500
                                                                                        11000
 Equipment Costs
   A typical catalytic oxidizer will include the following compo-
 nents:  (1) a waste gas fan; (2) combustion chamber and pre-
 heater, (3) catalyst bed; (4) heat recovery equipment; (5) con-
 trols, instrumentation, and control panel;  and (6) a stack. In
 addition, other equipment such as ductwork may be required to
 integrate the oxidizer with the remediation process. The equip-
 ment costs for an catalytic oxidation system can generally be
 estimated two ways: 1) by obtaining quotations from vendors, or
 2) by using generalized cost correlations available in the litera-
 ture.

  The purchased cost of a typical catalytic oxidation system will
yary widely depending on several design factors. Consequently,
caution is required when using generalized cost correlations.
Among thefactors that influence the purchased cost of a catalytic
oxidation system are the supplier's design experience, materials
of construction,  instrumentation, the type of catalyst used, the
type of heat exchanger used, and the nature of the installation
(i.e., Do any factors exist which make installing the equipment
unusually difficult?)
                                            Catalytic oxidizer equipment costs as a function of flue gas
                                          flowrate are shown in Figure 5-14 at standard conditions of 60°F
                                          and 1 atm (absolute). This figure is adapted from an article by
                                          Katari, et al., 1987b which used cost information from catalytic
                                          oxidizer manufacturers to develop cost correlations. The equip-
                                          ment costs given represent the cost for a complete oxidation
                                          system including a combustion chamber with burner, catalyst,
                                          waste gas fan, inlet and outlet plenums, prepiping, prewiring,
                                          instrumentation and controls, a 10-ft stack, and in the case of heat
                                          recovery, a primary heat exchanger.

                                            Another set of cost correlations for catalytic oxidation systems
                                          have been published recently (van der Vaart, et al., 1991). Using
                                          data provided by several vendors, the authors developed relations
                                          between the equipment cost and the flue gas flowrate for different
                                          levels of heat  recovery. Based on regressions the following
                                          correlations were established in 1988  dollars for fixed bed
                                          catalytic oxidizers having flowrates between 2,000 and 50,000
                                          scfm (Q is the flowrate in scfm, EC is  the equipment cost in
                                          dollars, and HR is the percent heat recovered):
                                                          54

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      Heat in
                                                                                Heat out
       Qfuel
 Heat from auxiliary fuel
        Qrel
Heat from combustion of
  VOCs in waste gas
                                        Catalytic oxidation
                                                                                             Qsens
                                                                                      Heat required to raise
                                                                                    waste gas temperature from
                                                                                         100°Fto700°F
                                                                                            I
                                              ^ recovery
                                    Heat recovered in heat exchanger
                           (Q recovery =  iQsens, where 11= efficiency of heat exchanger)
Figure 5-13. Heat balance for catalytic oxidation.


      EC - 1100 ' Q ?0f47  HR = 0%              (Eq. 5-10)

      EC - 3620 ' Q 0.419 HR - 35%             (Eq. 5-11)
                   tot
      EC = 1220-Q 0.558  HR = 50%             (Eq.5-12)

      EC = 1440 ' Q 0.553  HR = 70%             (Eq. 5-13)

  For fluidized-bed systems a second set of correlations, also in
1988 dollars, covering the range of 2,000-25,000 scfm were
developed based on data from vendors:

      EC - 8.48 x!04 + 13.2 ' Qtot  HR = 0%      (Eq.5-14)
      EC = 8.84xl04+14.6'Qtot  HR = 35%    (Eq.5-15)
      EC = 8.66 x!04+15.8-Q(t  HR = 50%    (Eq.5-16)
      EC = 8.39xl04+19.2-Q(M  HR = 70%    (Eq.5-17)

  The costs for fluidized-bed systems are higher, since these
units aredesigned to handle waste streams with (1) higher heating
values, (2) higher particulate contents, and (3) chlorinated spe-
cies.

  Cost estimates for systems to treat less than 2000 scfm should
be obtained directly from vendors.

Installation, Engineering, and Indirect Costs
  The total capital investment (TCI—equipment costs plus in-
stallation, engineering, and indirect costs) for a catalytic oxida-
tion system can vary widely as a function of the total equipment
cost. The TCI for a small  skid-mounted unit to be placed at a
preprepared site may be only 150-200% of the equipment cost.
On the other hand, for a custom installation, requiring extensive
site-work, the TCI may run as high as 300-400% of the purchased
equipment cost.
                                                   One method for generating an estimate of installation, engi-
                                                 neering, and indirect costs is to use the factor approach presented
                                                 in Table 5-6 in Section 5.2.5. Based on the approach given in this
                                                 table, the TCI is approximately 160% of equipment costs, plus
                                                 any costs for site preparation and construction.

                                                 Annual Expenses
                                                   Estimating the annual expenses associated with using catalytic
                                                 oxidation  requires  an extensive amount of site-specific data.
                                                 Suggested factors for estimating thermal oxidizer annual costs
                                                 are presented in Table 5-7 in Section 5.2.5. The only additional
                                                 cost consideration for catalytic oxidizers is capital recovery for
                                                 the catalyst material, This is a function of the catalyst life (e.g.,
                                                 3 years) and the interest expense. Overall utilities, the annualized
                                                 catalyst cost, and the system capital recovery are typically the
                                                 largest expenses.

                                                 5.4     Condensers
                                                 5.4.1   Process Description
                                                   Condensers are  primarily  used to remove VOCs from gas
                                                 streams prior to other controls such as incinerators or absorbers
                                                 but can also be used alone to control emissions  of high VOC
                                                 concentration gas streams. Condensation is a recovery technique
                                                 where the volatile components of a vapor mixture are separated
                                                 from the remaining gas by a phase change. Condensation occurs
                                                 when the partial pressure of the volatile components is greater
                                                 than or equal to its vapor pressure. This situation can be achieved
                                                 by lowering the temperature or increasing the pressure of the gas
                                                 stream.

                                                    Figure 5-15a is a simple process flow diagram for condensa-
                                                 tion. A typical condensation system consists of the condenser,
                                                 refrigeration system, storage tanks, and pumps. Figure 5-15b is
                                               55

-------
                  1000
                                     No HE

                                     35% HE

                                     50% HE

                                     70% HE
                              i     !    .    .   .  .
                             HE = Heat Exchanger1  •
                                                  10             20
                                                    Volume Flow Rate (1000 scfm)
                          50
           Source: Adapted from V. Katari, et al., 1987b.
 FIguro 5-14. Catalytic Incinerator equipment cost estimates.
 a more detailed process diagram of an entire condensation and
 recovery process. VOC off-gas is compressed as it passes through
 a blower. The exiting hot gas is routed to an aftercooler com-
 monly constructed of copper tubes with external aluminum fins.
 Air is passed over the fins to maximize the cooling effect. Some
 condensation occurs in the aftercooler. The gas stream is cooled
 further in an air-to-air heat exchanger. The condenser cools the
 gas to below the condensing temperature in an air-to-refrigerant
 heat exchanger. The cold gas then  is routed to a centrifugal
 separator where the liquid is removed to a collecting vessel. The
 aftercooler and heat exchanger may not be necessary for all
 condensing  systems. Typically, further treatment of the  gas
 stream isrequired for final polishing, such as acarbon adsorption
 unit, before the stream can be vented to the atmosphere.

  Condensing systems usually contain either a contact con-
denser or a surface condenser. Contact condensing systems cool
the gas stream by spraying ambient or chilled liquid directly into
the gas stream. The spraying is usually accomplished in a packed
column where surface area and contact time are maximized.
Somecontactcondensers aresirnple spray chambers with baffles,
while others have high velocity jets  designed to produce a
 vacuum. Since the coolant comes into direct contact with the
 recovered contaminants, the contaminants and coolant must be
 separated or extracted before either can be reused. This separa-
 tion process may lead to a disposal problem or secondary emis-
 sions. Contact condensers are more flexible, simpler, and less
 expensive to operate than surface condensers. Contact condens-
 ers usually remove more air contaminants due to greater conden-
 sate dilution.

   In surface condensing systems, the coolant does not make
 contact with the gas stream. These condensers are usually the
 shell and tube or plate/fin type. Condensed vapor forms a film on
, the cooled surface and drains into a collection vessel for storage,
 reuse or disposal. Condensation can occur in the tubes or on the
 shell outside of the tubes. Typically, condensers are the shell and
 tube type with the coolant flowing on the inside of the tubes
 counter-currently to the gas stream. Condensation occurs on the
 outside of the tubes in this arrangement. The condenser is usually
 horizontal but vertical condensers also exist. Surface condensers
 require less water and produce 10 to 20 times less condensate than
 contact condensers. Surface condensers are more likely to pro-
 duce a salable product. These type of condensers have a greater
 amount of maintenance due to the auxiliary equipment required!
                                                         56

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                           Emission Stream
                               Outlet
    Emission
     stream
        inlet
i
                       Condenser
         Condensed
         VOC
1
i
i
Coolant
Refrigeration unit

              Source: Taken from U.S. EPA, 1991
Figure 5-15a.     Process flow diagram for condensation.
5.4.2   Applicability to Remediation Technologies
  Condensation generally is used to remove and recover VOCs
prior to other control technologies. Condensation can be used
alone to control emissions at high VOC concentrations, i.e.,
greater than 5000 ppmv. This type of VOC control is not suited
for gas streams that contain organics with low boiling points (i.e.,
very low condensation temperatures <32°F) or gas streams with
large quantities of inert or noncondensible gases (air, nitrogen, or
methane). Condensation is a very efficient removal process for
high concentration streams.

  In most control applications, the emission stream will contain
large quantities of noncondensible gases and small quantities of
condensible compounds. Care should be taken,in design and
operation to ensure limited emissions of VOCs from discharged
condensate, i.e., secondary emissions. Further subcooling of the
condensate may be  required to  correct this situation.  If
uncondensible air contaminants are in the gas stream, these
contaminants must  be either dissolved  in the condensate or
vented to other control equipment. Since gas streams at Super-
fund sites will usually contain a variety of contaminants, the
recovered stream may not be salable due to purity requirements.
If so, the stream must be disposed of by incineration or some other
method. Another consideration is the moisture content of the gas
stream; any water in the stream will condense with the organic
vapors creating a dilute solvent stream. If the gas is not treated
below emission standards, the off-gas from the condenser must
be treated further, usually with activated carbon. Disposal prob-
lems and high power costs are some of the disadvantages associ-
ated with condensation.
                                           Air-Ccooled
                                           aftercooler
                                                                                           Centrifugal
                                                                                           separator
                                                                   Refrigerant in
                           Source:  Redrawn from APC, 1991 a.
 Figure 5-15b.     Schematic diagram of a vapor condensation system.

                                                          57

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 5.43   Range of Effectiveness
   Condensation has the capability of removing 50-95% of the
 condcnsible VOCs. The removal efficiency is dependent on the
 characteristics of the vapor stream and the condenser operating
 parameters. The efficiency depends on the nature and concentra-
 tion of emission stream components. For example, compounds
 with high boiling points (low volatility) condense more readily
 compared to  those with low boiling points. The temperature
 required to attain a given removal efficiency depends on the
 vapor pressure of the VOC at: the vapor/liquid equilibrium. The
 condensation temperature can be determined from data relating
 vapor pressure and temperature. The coolant selection is based on
 the required condensation temperature. Some practical limits for
 coolant selection are presented in Table 5-11.

 Table 5-11.  Condensation Temperature Limits for Various
           Categories of Coo'ants
        Required condensation
           temperature (°F)
              Coolant
                80-
               60-80
               45-60
              -30-45
             -90 to -30
                Air
               Water
            Chilled water
           Brine solutions
               Freons
  The effect of volatility on the condensation temperature and
removal efficiency is shown in Figure 5-16. The two components
have varying atmospheric boiling points, as shown on the figure.
For a given inlet concentration of contaminant, the removal
efficiency increases for a given condensing temperature as the
boiling point increases.          ,.'.!.-.,'.

5.4.4   Sizing Criteria
  Sizing the condenser involves several steps to determine the
surface area of the condenser. For a condenser system containing
a shell and tube heat exchanger, with condensate forming on the
shell side, the following design procedure can be followed (U.S.
EPA, 1991). The waste gas stream is assumed to be a  two
component mixture: a condensible component (VOC) and  a
noncondensible component (air). For estimating the condensa-
tion temperature, the gas stream consists of air saturated with a
VOC component. For a given removal efficiency, the partial
pressure in mm Hg for the contaminant in the exiting stream,
Pparti;i,, can be calculated:
  Ppartial=760.
                (1-0.01 RE)
             [l-(RExlO-8HAPe)|
•HAPC x 10"6
(Eq. 5-18)
 Source: Adapted from U.S. EPA, 1991.
           100
            80
            60
           40
           20
	Toluene (bp = 231 °F)

	  Xylene (bp = 292°F)
                     Basis: 20,000 ppmv Dry Waste Gas
                         10
          20
                                               30          40         50

                                             Condensing Temperature (°F)
                                                       60
                                70
                                                                             80
Figure 5-16. Example of condenser performance.
                                                        58

-------
  where:
        RE      =   Removal efficiency, %; and
        HAPe    =   Contaminantconcentration in entering gas
                     stream, ppmv.

  The condenser is assumed to operate at a constant pressure of
1 atmosphere. The condensing temperature can then be deter-
mined from equilibrium data where the calculated partial pres-
sure of the hazardous air pollutant (HAP) is equal to its vapor
pressure at that temperature. After the condensing temperature is
determined, the appropriate coolant can be selected using Table
5-11 as a guide.      •'.•.<••'.

  The heat load of the condenser can be determined from an
energy balance:
        Hload = 1.1 x60(Hon + Honcon + H nron)    (Eq.5-19)
  where:
        H,
          'bad
Condenser heat load, Btu/hr;
        H       =   Enthalpy of the condensed HAP; and
        H
Enthalpy of the noncondensible vapors.
                                           These parameters are defined in Table 5-12. Equations for
                                         determining these enthalpies are also given in this table. The
                                         factor 1.1 is included as a safety factor in the design.

                                           Condenser systems are typically sized based on the total heat
                                         load and the overall heat transfer coefficient. The overall heat
                                         transfer coefficient is estimated from individual heat transfer
                                         coefficients and from coefficients of the gas stream and coolant.
                                         An accurate measurement of the individual coefficients can be
                                         made from physical/ chemical data  for the gas  stream, the
                                         coolant, and the specific shell and tube that is to be used. Some
                                         typical heat transfer coefficients for  condensing systems are
                                         presented in Table 5-13. Condensers are sized from their area by
                                         the following equation:
                                                                where:
                                                                      U
                                                                                Acon =  Hload/UAT,
                                                                                                 LM
                                                                                         (Eq.5-20)
Condenser surface area, ft2;
Overall heat transfer coefficient, Btu/
hr-ft2-°F; and
Table 5-12. Design Equations for Condensing Systems
                                                        Equations
                                           Hc0n = HAPcon [AH + CPHAP (Te - Tcon ) ]



                                               Huncon = HAP0,m CPHAP (Te - TCOn )



                                           Hnoncon - [(-^-) - HAPe,mJ CPair (Te - Tcon
                                                 HAPcon = HAPe,m-HAPo,ra


                                                = -^-)[l - HAPe X 1 O'6] [  Pvapor
                                                 ^392/               [(P.- Pvapor.
                                                 HAPe m = -^-
                                                     '   V3921
                                       CP
                                       HAP,
                                       HAP,
                                       HAP,
                                       AH
                                 Nomenclature
                                 Average specific heat of compound, Btu/lb-mol-°F
                                 Entering concentration of HAP, ppmv
                                 Molar flow of HAP, inlet Ib-mol/min
                                 Molar flow of HAP, outlet, Ib-mol/nim
                                 Heat of evaporation, Btu/lb-mol
                                 System pressure, mm Hg

                                   partial
                                 Maximum flow rate, scfm at 77° F and 1 atm
                                 Condensing temperature, °F
                                 Entering emission stream temperature, °F
Source: U.S. EPA, 1991.
                                                           59

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 Table 5-13. Typical Overall Heat Transfer Coefficients in Shell and
           Tube Heat Exchangers for Condensing Vapor-Liquid
           Media
Shell side
High-boiling
hydrocarbons, V
Low-boiling
hydrocarbons, A
Organic solvents, A
Organic solvents
Mgh.NC.A
Organic solvents
tow NC, A
Tube side
Water

Water

Water
Water or brine

Water or brine

Design U
(Btu/ °F-
ft*-hr)
20-50

80-200

100-200
20-60

50-120

Fouling factor
(hr-ft2-°F/Btu)
0.003

0.003

0.003
0.003

0.003

 V  -    Vacuum
 A  -    Atmospheric pressure
 NC »    Non-condensiMe gas present

 Source: Adapted from Perry, 1973.
     AT,
        LM
Logarithmic mean temperature difference,
op
(Tc-TCMl,0)-(Tcon-TCM|.)

lnKTc-TCOOI>0)-(Tcon-Tcoo,.)]

Emission stream temperature, °F;
Coolant outlet temperature, °F -
                     Coolant inlet temperature, °F = (T   - 1 5)
    where:
The coolant flow rate can be determined from a simple heat
balance:
                    H,«/[CPcMlM(Tcool_o -T^,.)]  (Eq. 5-21)
                    Coolant flow rate, Ib/hr; and
                    Average specific heat of the coolant, Btu/
  The design procedures are more complicated for a mixture of
condensible gases in a noncondensible gas. More information for
determining the condensation temperature for these type of
mixtures can be found in Lud wig, 1965 and Kern, 1950. Physical/
chemical data can be found in Perry's Chemical Engineers'
Handbook, Smith and Van Ness, 1959, and CRC, 1992. Walas,
1988 and Danielson, 1967 have more information on condenser
design.

  If a refrigerant is chosen for the coolant, then a refrigeration
system also must be designed for the condensing system. The
refrigeration capacity, Ref, in units of tons is determined from:
            Ref - H10M/12,000 Btu/hr-ton
                           (Eq. 5-22)
                                                             5.4.5    Cost Estimating Procedure
                                                               The following cost equations are for refrigerated surface
                                                             condenser systems. These cost correlations are in 1 990 dollars; a
                                                             factor of 1.1025 should be applied to these figures to convert to
                                                             1992 dollars. The refrigeration unit equipment cost (ECr) for
                                                             packaged solvent vapor recovery systems can be determined by
                                                             the following equations (Shareef, et al., 1991):

                                                               •      Single stage refrigeration units (less than 10 tons)

                                                                  ECr = exp(9.83 - 0.014Tcon + 0.341nR)        (Eq. 5-23)

                                                               •      Single stage refrigeration units (greater than or equal to
                                                                     10 tons)

                                                                  ECr = exp(9.26 - 0.007Tcon + 0.6271nR)       (Eq. 5-24)

                                                               •     Multistage refrigeration units

                                                                  ECr = exp(9.73 - 0.012Tcon + 0.5841nR)       (Eq: 5-25)

                                                               These costs were determined from vendor-supplied informa-
                                                             tion. The equipment cost for packaged solvent vapor recovery
                                                             systems, ECp, is estimated to be 25% greater than the refrigera-
                                                             tion unit cost. The purchased equipment cost, PECP, includes the
                                                             packaged equipment costs and factors for sales tax and freight:

                                                                      PECp - 1 .08 ECp = 1 .08 (1 .25 ECr)      (Eq. 5-26)

                                                               Equipment costs for custom solvent vapor recovery systems
                                                             were developed by (Shareef, et al., 1991). The following equa-
                                                             tions can be  used to determine the capital costs (limitations are
                                                             noted):
                                            EC
                                                                  condcnsCr
                                                                                 34Acondcnscr + ^775'          (Eq. 5-27)
                                                                                 38 to 80° ft2 of 304 stainless steel tubes
                                            ECU     =     2.72^ + 1960;            (Eq. 5-28)
                                            Vtank      =     50 to 5000 gallons, 3 1 6 stainless steel

                                          The estimated cost of the precooler can be determined from the
                                        refrigeration unit costs by using Equations 5-23 to 5-25. The cost
                                        of auxiliary equipment such as ductwork, piping, fans, or pumps
                                        also needs to be determined by procedures outlined in (Vatavuk,
                                        1990). The total equipment cost for custom systems and the
                                        purchased equipment cost can be described by:
                                            EC,
                                            PEC,
                                                                                       (Eq.5-29)
                                                                                1.18EC
       ~c     ~     I.JLO^V.C   ,                (Eq. 5-30)
  The total capital investment can then be determined for pack-
aged and custom systems by the following:

          TCI - 1.15PECp or TCI = 1.74PECC     (Eq. 5-31)

  The total annual operating cost correlations are summarized in
Table 5-14. This table contains the basis for calculating direct
                                                         60

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 Table 5-14. Annual Cost Factors for Refrigerated Condenser Systems

                         Cost items
                                                                                                  Factor
Direct Annual Costs, DC
Operating labor
    Operator
    Supervisor

Operating materials
  Maintenance
    Labor
    Material

  Electricity
    at 40° F
    at 20° F
    at -20° F
    at -50° F
    at-100° F

Indirect Annual  Costs, 1C
  Overhead
  Administrative charges
  Property tax
  Insurance
  Capital recovery "

Recovery Credits, RC
  Recovered VOC
                         Total annual costs:
                                                                                                    1/2 hour per shift
                                                                                                     15% of operator
                                                                                                    1/2 hour per shift
                                                                                           100% of maintenance labor
                                                                                                         1.3kW/ton
                                                                                                         2.2 kW/ton
                                                                                                         4.7 kW/ton
                                                                                                         5.0 kW/ton
                                                                                                        11.7kW/ton
                                                                         60% of total labor and maintenance material costs
                                                                                          2% of total capital investment
                                                                                          1% of total capital investment
                                                                                          1 % of total capital investment
                                                                                       13.15% x total capital investment
                                                                                   Quantity recovered x operating hours

                                                                                                       DC + 1C - RC
• Assuming a 15-year life at 10%.

Source: Reprinted from Shareef, et al., 1991.
annual costs, indirect annual costs, and recovery credits. The
recovery credit, RC, may not be applicable if the product purity
is not high enough for resale. The recovery credit can be deter-
mined from the quantity of VOC recovered:
                RC = W,
                        VOC.con  s ^ VOC
                                           (Eq.5-32)
where:
    W,
    9,
    Pvoc
          voc,con
             '
=   Quantity of VOC recovered (Ib/hr);
=   System operating time (hr/yr); and
-   Resale value of recovered VOC ($/lb).
  Other cost correlations can be found in U.S. EPA, 1991 and
Walas, 1988.

5.5     Internal Combustion Engines
5.5.1   Process Description
  The principle of operation of acontrol device that incorporates
an internal combustion engine (ICE) is to use a conventional
automobile or truck ICE as a thermal incinerator. The physical
difference between ICE units and incinerators is primarily in the
geometry of the combustion chamber. A simplified schematic of
a typical ICE-based system is shown in Figure 5-17. The major
components include the engine itself (standard automobile or
truck engine), supplemental fuel supply (usually  propane or
natural gas), carburetor, off-gas lines from remediation system,
and  additional air emission control devices (adsorbent bed,
catalytic converter, etc.). Some pretreatment device also may be
required, since ICE units require a "clean" waste stream contain-
ing no acids and low levels of particulate matter.

  Supplemental fuel is required when the VOCs in the waste
stream are at insufficient concentrations to support combustion.
This requirement is especially common for system start-ups,
remediation projects with low VOC extraction rates, and sources
such as SVEs that produce changing VOC concentrations over
time. Concentration ranges of 60,000 to 100,000 ppm at flo wrates
of 1.7 - 2.0 m3/min  (60 - 70 acfrn) are possible (RSI, 1991a).
However, additional oxygen may be required to dilute the gas
stream if the VOC level exceeds 25% of the lower explosive
limit. The carburetor must be modified to include two input
valves (in addition to the change allowing gaseous rather than
liquid fuel).

  A major advantage to the technology is the mobility of an ICE
unit. This advantage may be enhanced if all power needs are met
by the ICE, and no external power source is needed to drive the
remediation equipment. The ready availability of automobile
parts and wide knowledge of their operation are other advan-
tages; even the catalytic converter as an add-on control is inex-
pensive if an automobile manufacturer's unit is used.

5.5.2   Applicability to Remediation Process
  ICEs may be used for VOC control from any point source
where the air stream meets certain criteria. To be economically
attractive the stream should be of relatively  small flow rate
                                                          61

-------
                                                                                                 Clean air out
                                Supplemental
                                 fuel and air
                                                                                                         Muffler
          VOC
        olf-gas-
r~Fr
                                         Six cylinder engine
                                                         Catalytic
                                                         converter
-cr
 Blower
                     Carburetor
                                   o
 Figure 5-17. Internal combustion engine-based VOC control system.
(< 1,000 cfrn) since the largest ICE is only capable of a few
hundred cfm, and it should contain high concentrations of VOCs
(> 1,000 ppm) or else supplemental fuel costs would become
excessive. For applications involving large flow rates of dilute
waste gas, however, the technology still may be potentially cost-
effective if used in conjunction with a condenser, membrane, or
other pre-treatment concentrator.

  ICEs have been used for years to control landfill gases, but they
have been applied to hydrocarbon destruction only since 1986,
primarily forS VE and air stripping. Their use is most common in
California, where die majority of ICE system manufacturers are
located (Pedersen and Curtis, 1991). Their use at Superfund sites
is expected to be limited to the control of VOC emissions from
small-scale S VE systems and perhaps to small-scale air strippers.
In general, arelative lack of information exists concerning details
of ICE technology for site remediation purposes. Their use to
date, is limited due to the relatively small flow rates (hundreds of
cfms) that these units are able to handle. To date, the  limited
available literature has focused on ICE use for SVE,  landfill
capping, and air stripping applications.

  The use of ICEs is especially attractive when it replaces the
need for electrical  power to the site by using the engine to run
vacuum fans, etc. This use saves not only utility costs, but
equipment costs as well. DREs of 99+% may be achieved,
usually with a catalytic converter in place. Other advantages of
ICEs over other VOC destruction systems are in mobility and
size. The potential problems of excessive noise and labor require-
ments (for monitoring fuel intake) may be avoided by the use of
computer-controlled air-to-fuel ratios and sophisticated muffler
systems. ICEsystems with automated controls are recommended
for Superfund applications.
                                  5.5.3   Range of Effectiveness
                                    ICE systems typically can achieve destruction efficiencies of
                                  99% or greater. A recent report (Pedersen and Curtis, 1991)
                                  contains the results of several studies listing removal efficiencies
                                  of different VOCs by ICEs for various SVE and air stripping
                                  systems. These results are presented in Table 5-15. Additional
                                  case study information for specific ICE units  is summarized
                                  below.

                                    One vendor, VR Systems, has a series of portable ICEs that are
                                  designed for use with SVE systems and also can perform tank de-
                                  gassing. These units burn up to 100 kg/hr (220 Ib/hr) of hydrocar-
                                  bons. They use liquid propane or natural gas as a supplementary
                                  fuel, and are computer-controlled for higher DREs and less labor
                                  requirements.

                                    The Soil-Scrub(R) process  (K-V Associates, Falmouth, MA)
                                  was used with a heat-assisted SVE system (HWC, 1988). An ICE
                                  was the primary control for this system, followed by a catalytic
                                  converter and a GAC bed. Gasoline-soaked soil was first encap-
                                  sulated in plastic sheets, then  the soil was heated to 100°C. The
                                  final DRE was 99.9% upon exiting all controls. The entire
                                  remediation process took 36 hours, and the treated soil contained
                                  no detectable benzene, toluene, and xylenes and only 82 ppm oil.

                                    A thermal vacuum spray aeration/compressive thermal oxida-
                                  tion system (Robert Elbert & Associates, Santa Barbara, CA)
                                  incorporating an ICE has been used for ground water remediation
                                  (HWC, 1988). Heat (110°F) and vacuum  (12" Hg) were used to
                                  preferentially evaporate gasoline from water, and the vapor was
                                  sent to an ICE. The  system can  strip  and oxidize  120 Ibs
                                  hydrocarbons/ day; the treated water had  32 ppm contaminants
                                  and the waste gas had 70 ppm.  It required approximately 0.75 gal
                                  fuel/hr. Two  limitations to the process were noted: over-rich
                                                       62

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Table 5-15. Destruction Efficiencies of ICEs for SVE Systems
Parameter
THC

THC
Benzene
Ethylbenzene
Toluene
Xylenes
TPH (non-methane)
Methane HCs
Benzene
Toluene
Xylenes
Ethylbenzene
TPH



Benzene



THC
Benzene
Toluene
Ethylbenzene
Total xylenes
THC
Benzene
Toluene
Ethylbenzene
Total xylenes
Initial concentration
(ppm)
38,000
200,000 .
318,832
995
125
1,005
1,550
49,625
741
380
400
114
18
65,450
34,042
30,500
39,000
• 1,094
470
785
730
58,000
1,400
720
77
320
26,000
960
840
91
360
After catalytic
converter (ppm)
89
39
16 ppm
ND1 (<10ppb)
ND (<10ppb)
0.014
<11.5ppb
225
109
0.8
1.1
0.7
<0.5
30
14.5
1.4
4.7
67
1.6
0.63
,0.056
160
0.13
0.024
0.062
0.13
140
0.024
0.020
ND (0.02)
0.080
Removal efficiency
(%)
99.76
99.98
99.99
99.99
99.99
99.99
99.99
99.56
85.29
99.79
99.73
99.39
—
99.95
99.96
99.99
99.99
93.88
99.66
99.92
99.99
99.72
99.99
99.99
99.92
99.96
99.46
99.99
99.99
100.00
99.98
Reference
Millican,1989
Millican, 1989
Wayne Perry, 1989
Wayne Perry, 1989
Wayne Perry, 1989
Wayne Perry, 1989
Wayne Perry, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
Rippberger, 1989
Rippberger, 1989
Rippberger, 1989
Rippberger, 1989
Rippberger, 1989
Rippberger, 1989
Rippberger, 1989
, Rippberger, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
RSI, 1989
'Nondetectable

Source: Pedersen and Curtis, 1991.
 combustion conditions may be met if the remediation process
 occurs in a well, and the system can be smothered with excessive
 water vapor.

 5.5.4  Sizing Criteria/Application Rates
  The sizing of an ICE device is based on the volumetric flow rate
 of the waste stream to be treated. Information from several
 vendors is summarized below (VR Systems,  1991 and RSI,
 1991b).

  VR Systems has various SVE-ICE systems with controllers
 ranging in sizes from 25 to  1,000 scfm. This largest system is
 actually several engines in parallel, and can destroy about 20 Ib7
 hr of hydrocarbons. RENMAR, on the other hand, reports that
 their SVE system is able to accommodate 100 to 200 scfm of
 input gas (depending on the loading) for every 300 cubic inches
 of engine capacity (Pedersen and Curtis, 1991). RSI manufac-
 tures a system that can accommodate either SVE or air stripping.
 Their ICE unit can handle up to 80 cfm of VOC-laden air.
5.5.5   Cost Estimating Procedure
  Only limited cost data are available. A recent listing of several
commercially available systems and their prices is given in Table
5-16.

  One vendor (RSI, 1991 a) compares this technology to a carbon
adsorption system; consider an example case of a $2 carbon cost
per pound of hydrocarbon adsorbed. If an ICE system leases for
$200 per day, burns $100 per day of supplemental fuel, and
destroys 15 Ibs/hr of hydrocarbon, then the cost per Ib is $3007(24
x!5) = $0.83. For this example, the cost-effectiveness cross-over
occurs at a VOC extraction rate of around 8 pounds/hour, at
which point the carbon becomes preferable.

  One ICE manufacturer, RENMAR, claims an SVE system
uses only 25% of useful power so that excess power is available
for site lighting, etc., and thereby increasing the cost-effective-
ness of an ICE system. In general, however, the excess power
produced will depend on the difference between the work needed
to extract the vapors and the energy available in the vapors.
                                                         63

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 Table 5-16. Costs for Some Commercially Available ICE Systems
          Vendor
System
  size
 (scfm)
  Cost
 capital
  Cost
lease per
 month
  Op.
expense
                                                                                                    Comments
 RSI
 RENMAR
 VR Systems:
   Model V-3
   Model V-4
   Model V-5

 Environmental techniques
                                    30-60
                                   100-200
 0-250
 0-500
0-1.000

  100
                $59,500
                $52,100
$73,450
$98,880
custom

$40,250
bydistrib.        $1,000        For SVE and groundwater
                             systems. Includes 8 hours
                             start-up labor.

 $4,630                      Prices updated from 1989
                             levels.

                             Includes operating cost: lease
 $6,980                      based on 3 months. Custom
 $9,775                      built only.
                                                                                                Includes operating and
                                                                                                maintenance. Training for
                                                                                                oxygen recording system:
                                                                                                $2,700.
 Source: Vendor-supplied data.
 5.6     Soil Beds/Biofflters
 5.6.1   Process Description
   Biofil tration is an emerging technology for controlling volatile
 organic compound (VOC) emissions in waste gas streams. Bio-
 filtration has been extensively used inEurope, especially for odor
 control. Biofiltration has been demonstrated at full-scale (Leson
 and Winer, 1991). In the biofiltration process, the waste gas is
 vented through a biologically active material where the biode-
 gradable VOCs are oxidized into carbon dioxide  and water.
 Physical sorption and chemical degradation may also occur and
 contribute to the overall removal efficiency. Figure 5-18 is  a
 schematic of a typical single-bed biofilter system. Since the
 biofilter system is biologically sensitive, the temperature and
 moisture of the gas and filter bed are extremely important in
 design considerations. Radial blowers are used to transport the
 waste gas  to the humidifier. The humidifier saturates the gas
 stream to 95% relative humidity, which prevents drying out of the
                            filter material. The effect of the filter drying out is death of the
                            microorganisms and a resultant loss of control efficiency.

                              Some systems have automatic irrigation from the top of the
                            filter (soil) bed. The gas stream then enters the gas distribution
                            system below the filter. As the gas diffuses through the filter, air
                            contaminants will diffuse into the wet, biologically active layer
                            (biofilm) where degradation occurs. Clean gas diffuses out the
                            top of'the filter. Excess drainage from the filter bed is the only
                            potential source of wastewater discharge. In particular, where
                            drainage contains organic contaminants that are regulated, the
                            drainage is recycled to the humidifier to minimize wastewater
                            discharge. Since particulates in the waste stream may clog the
                            humidifier and the biofilter, a pre-filter may be required. A heat
                            exchanger may also be required  to heat or cool the waste gas
                            stream if temper-atures are not within the optimum range (i.e.,
                            20-40°C).
                                                                                                 Clean Gas
                                                                                                    Biofilter
                                                     Humidifier
                                       Drainage
      Raw Gas
Figure 5-18. Schematic of an open, single-bed biofiltration system.
                                                           64

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  Typically, the filter material is compost, peat, wood chips, or
soil with an inert material such as polystyrene particles or porous
clay. As the VOCs are degraded, water, carbon dioxide, mineral
salts, and biomass are generated. Mineralization leads to com-
paction of the filter material which causes an increase in back
pressure. Typically the filter material is turned over after 2 years
of operation and usually replaced 1 -2 years after turning over the
filter to prevent back pressure problems (Leson and Winer,
1991).

  The  most common biofilter system is an  open, single-bed
system. The clean gas is vented directly to the atmosphere in an
open biofilter. Enclosed, multiple-bed systems can be stacked
and have been employed for low maintenance and space con-
straint situations.

5.6,2   Applicability to Remediation Technologies
  The applicability of biofiltration is dependent on the character-
istics  of the waste gas. Typical  biodegradable contaminants
include: alcohols, ethers, aldehydes, ketones, amines, sulfides,
and certain monocyclic aromatics (xylene, benzene, toluene and
phenol). Waste  streams containing chlorinated solvents are not
readily biodegradable and are not appropriate for emissions
control by biofiltration.

  Biofiltration,  as a  VOC control technology,  results  in the
complete degradation of the biodegradable contaminants  and
avoids the cross media transfer of pollutants.  A major require-
ment,  and  thus limitation,  of  biofiltration is the absence of
biologically toxic substances in the waste gas, such as  heavy
metals. The technology is limited to biodegradable components.

  Since biofiltration is biologically sensitive,  the potential sys-
tem failures represent areas that should be considered when
evaluating this  technology. An undersized filter can result in
VQC air emissions due to insufficient treatment. Since the filter
is sized by off-gas flow rate and concentration, the off-gas should
remain within these design parameters during operation to pre-
vent the loss of control efficiency. Inadequate preconditioning of
the off-gas for temperature, moisture, particulates, or toxic con-
stituents can also result in the complete loss of control efficiency.

  Intermittent off-gas streams  can be treated with a biofilter
assuming the flow rate and concentration of the gas stream are
within the  design values. Filter beds can survive shut  down
periods of at least two weeks without any significant reduction in
biological activity. Shut down periods up to two months are
feasible with nutrient addition and aeration of the filter (Leson
and Winer, 1991).

  Biofiltration is not known to be used as a control technology at
any Superfund sites, but this technology would be an appropriate
VOC control for large volume gas streams with low concentra-
tions (e.g. certain soil vapor extraction systems). One potential
use of biofiltration is odor control at Superfund sites assuming the
odor constituents are biodegradable. Since odor problems usu-
ally are caused by compounds with low odor thresholds, off-gas
concentrations often  will be relatively low (Leson and Winer,
1991).  Biofiltration also may be  an appropriate treatment for
VOCs that have already been reduced -by a primary control
device. The lower concentration off-gas stream would require a
smaller filter size, which results in lower capital costs.

5.6.3   Range of Effectiveness
  Biofiltration usually is cost effective for large volume gas
streams with relatively low concentrations (<  1000 ppm as
methane) of easily biodegradable contaminants (Leson and Winer,
1991). Maximum influent VOC concentrations have been found
to be 3000-5000 mg/m3 (Leson and Winer, 1991). For optimum
efficiency, the waste gas should be 20-40°C and 95% relative
humidity. The filter material should remain at 40-60% moisture
by weight and have a pH between 7 and 8 (Leson and Winer,
1991). For most easily biodegradable constituents, control effi-
ciencies greater than 90% are achievable (APC, 1991b). Degra-
dation rates for common air pollutants are typically from 10 to
100 g/m3-hr (Leson and Winer, 1991).
  The key parameters affecting the control efficiency of a biofil-
tration system include the environmental conditions in the filter
material, biofilter design, filter size, and waste gas composition.
The filter must also have a large reactive area and low pressure
drops; therefore, compaction must be kept to a minimum.

5.6.4   Sizing Criteria
  Typical biofilter systems  have been designed to treat 1,000-
150,000 m3/hr waste gas with the systems having 10-2,000 m2 of
filter  area  (Leson and Winer,  1991). The depth of biofilter
material is typically  three to four feet. The size of a biofilter
system is dependent on the following parameters:

  1)   The loading rate of waste gas;
  2)   The concentration of compounds in the waste gas; and
  3)   The rate of degradation of the compounds per unit volume.

  Surface loads up to 300 m3/hr of waste gas per m2 filter area are
feasible without excessively high back pressures (Leson  and
Winer, 1991). The type of filter material affects the pressure drop
across the filter. The effect of filter material on pressure drop is
shown in Figure 5-19 as a function of the surface loading rate.
    3000
  2 2000
    1000
Conventional Filter
Compost
 Optimized Filter
 Compost
 Mixed with Coarse
 Bark
12

10 g.

8  s_

6  Q

4  I

2  ol
                100      200     300     400
                     Surface Load (m3m-2rr1)
                 500
                                                             Figure 5-19.  Pressure drop for two filter materials as a function of
                                                                         surface loading rate.
                                                          65

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  Higher surface loads render the biofilter more susceptible to
  dehydration and heat losses caused  by insufficient raw gas
  conditioning. The filter's large mass often provides sufficient
  buffer capacity to prevent breakthroughs during peak loadings,
  which allows sizing based on average hourly peak loads (Leson
  and Winer, 1991).

   The removal process in biofilters has been postulated to be
  controlled initially by a first-order-type biodegradation rate, but
  to be limited by transport properties at low inlet air flow rates
  (Miller and Canter, 1991). Pilot testing of industrial waste gas
  streams with multiple contaminants is usually required, rather
  than modelling, to accurately size the full scale system.

  5.6".5   Cost Estimating Procedure
   Capital costs have been estimated at $60-95 per ft2 filter area
  for installed open, single-bed biofilter systems. Gosts of open,
  multiple-bed systems are approximately two times these costs.
  Enclosed systems have been estimated to cost between $95-525
  per ft2 filter area, depending on the size of the biofilter and the
  degree of process control (Leson and Winer, 1991). Operating
  costs are $0.35-1.60 /100,000 SCF, not including filter replace-
  mentcosts (APC, 1991b; Leson and Winer, 1991). Maintenance
  costs are abou t one labor hour per square meter of filter per year.

  5.7    Operational Controls
   Operational controls are thoseprocedures or practices inherent
  to the operation (and design)  of control systems  that can be
  followed to minimize the overall long-term emissions. Among
  these arc:
     Adequate system design and installation;
     Startup testing;
     Preparation of standard operating procedures for opera-
     tors;
     Control of operating variables to minimize emissions;
     Monitoring of system performance;
     Minimization of process upsets and startups; and
     Preventative and routine maintenance.
   Obviously, a properly designed and operated control system is
 necessary to achieve the required emission control efficiency or
 emission limits. The use of experienced contractors and vendors
 will help ensure that the system design and installation are done
 correctly. Startup testing is advisable, with as many test condi-
 tions examined, aspossible, and all meaningful datarecorded and
 evaluated. Systematic checks of wiring, direction of fan and
 pump rotation, integrity (leak, tightness), etc. should be made.
 The startup testing results should be incorporated into the formal
 standard operating procedures (SOPs) prepared for and followed
 by the operators of the equipment.

   Supcrfund remedial actions tend to present special problems
 that affect control system operation arid effectiveness. The waste
 or soil to be treated tends to be highly heterogeneous which
 results in off-gas streams with variable composition. Further, the
 remediation activities themselves tend to start and stop due to
.problems with equipment, weather, schedule, etc., therefore the
 control systems frequently may encounter non-steady state con-
 ditions (e.g. startup). The control  efficiencies reported in this
  document are based on steady-state operating conditions and
  emissions will be significantly higher during startup, process
  upsets and excursions, or when the off-gas stream is out of design
  specifications.

    Operating variables can be controlled to minimize emissions.
  The most obvious variable to control is the treatment rate; e.g.,
  the lower the feedrate to an incinerator, the lower the mass of
  potential emissions. Other variables such as the aeration rate for
  biodegradation systems, also directly influence emissions. Con-
  trolling operating variables to minimize emissions is not always
  straightforward. There may be a number of competing variables
  that must be balanced for optimal control system performance.
  For example, reheating of off-gas streams prior to carbon adsorp-
  tion systems frequently is done to lower the relative humidity of
  the gas stream and improve performance. However, the higher
  temperature can affect performance negatively. These two com-
  peting requirements must be offset. Similarly, pressure drop
  versus control efficiency and operating cost is often an issue.

   To properly operate control devices, the system design and
  performance  must be understood. Performance  data can be
  generated by routine monitoring of influent and effluent emis-
  sion levels, pressure drops, operating temperatures, and so on.
  Operators should maintain the monitoring system so thatplugged
  lines, water in the lines, etc. don't result in misleading readings.

   Proper maintenance is another obvious requirement for suc-
  cessful control system operation, including routine inspection of
  the equipment and implementation of corrective  action when
  needed.

  5.8     Membrane Technology
 5.8.1    Process Description
   Membrane technology is  an emerging control  process for
 volatile organic compound emissions in waste gas streams. The
 membrane module acts to concentrate the organic solvent by
. being more permeable to organic  constituents than air. The
 imposed pressure difference across a selective membrane drives
 the separation of the solvent from the gas stream.

   A schematic of a typical membrane separation process is
 shown in Figure 5-20. The pressure difference is caused by either
 a vacuum pump on the permeate side of the membrane module
 (Figure 5-20a) or a compressor before the membrane separator
 (Figure 5-20b). Collected VOC emissions are transported to the
 membrane module by either a blower or compressor. The im-
 posed pressure difference across the membrane drives the sepa-
 ration of the feed gas into a concentrated stream (permeate) and
 a depleted residue gas stream. Most of the organic contaminant
 is transferred through the membrane with some gas permeating
 the membrane. The stripped off-gas is either vented or recycled
 to the VOC source.

   The concentrated permeate stream must be treated further to
 either  recover or dispose of the contaminants. In membrane,
 systems, the membrane functions to concentrate the VOCs in the
 stream. .The  permeate may  be  treated in various ways.  The
 process configurations for recovering the contaminants are
 shown in Figure 5-21.
                                                         66

-------
                                        Blower
                                                                                  Stripped
                                                                                  off-gas
                                                                                                 >• Permeate
Figure 5-20a.     Membrane separation system with vacuum pump.
                                       Compressor
Figure 5-20b.     Membrane separation system with compressor.
                                                                               Vacuum pump
                                                                                  Stripped
                                                                                   off-gas
                                                                                        Membrane
                                                                                        module
                                                                                  Permeate
  In Figure 5-2la, the recovery system consists of a carbon
adsorption system to collect the solvent. The solvent is recovered
during the steam regeneration process. The vapor stream from the
regeneration process is condensed and then decanted to separate
the water from the recovered solvent. Membrane Technology
and Research, Inc. (MTR) has developed and patented aprocess
(Baker, et al., 1984) to recover the solvent by condensation after
concentration by the membrane (Figure 5-21b). Figure 5-21c
represents a membrane system that collects the solvent by direct
condensation  of  the permeate  and  polishes  the  stripped gas
stream with activated carbon to remove any residual VOCs.
Incineration also  can be used to destroy the contaminants in the
concentrated stream.

  The membrane module itself consists of an ultrathin layer of a
selective polymer supported on a porous sublayer. The polymer
layer acts as the selective barrier; the microporous substructure
provides mechanical strength for the module. Typical membrane
materials include rubber (silicone and nitrile), PVC, neoprene,
silicone polycarbonate, and other polymer compounds. In a
spiral-wound membrane module,  layers of the  polymer are
supported on a mocroporous structure. The module can also be in
the hollow tube form. Either a blower and vacuum pump or a
compressor is required to supply the pressure differential re-
quired for separation across the membrane. Other equipment
requirements depend on the process configuration.

5.8.2   Applicability to Remediation Technology
  Membrane technology as a control device for VOC emissions
is an emerging technology. Some of the theoretical aspects of the
technology are being developed; at this time, only very limited
practical applications exist. Typically, a membrane separation
system would be used as a concentrator prior to other VOC
control devices. The concentrated waste stream generated from
the membrane module could be used to reduce the size and,
therefore, the capital and operating requirements of the primary
VOC control device.

  The industrial applications that are best suited for membrane
technology are situations that require a high quality recovered
product and  situations where carbon adsorption will not work
                                                         67

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                                     Stripped off-gas
                                                                                                              Condensed
                                                                                                              VOCs
    Steam
 Figure 5-21a.     Membrane concentrator with carbon bed adsorption recovery system.
                                                                                                      Water
                                                                             Clean gas to vent
                       Waste
                       sream
                                         Gas
                                         recycle
                         Condenser
                                 Condensed VOCs

Figure 5*21b.     MTR single-stage membrane system.
                            Membrane
                            module
                                                                              Vacuum pump
                          Clean gas to vent  -*-
Carbon adsorption unit
                                                Blower
                       Waste
                       stream
                                     Gas
                                  recycle
                          Condenser
                                     Membrane
                                     module
                                  Condensed VOCs

Figure 5-21c.     Single-stage membrane separation system with carbon bed adsorber polishing.
                                                                                      Vacuum pump
                                                          68

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(e.g. recovery of ketones or aldehydes due to fire hazard or 1 ,1 , 1
- trichloroethane due to its reactivity with the carbon). Several
options are available for further treatment of the permeate. Direct
condensation of the solvent is feasible at higher concentrations,
especially for solvents that are expensive or where recovery is
necessary. Incineration would be appropriate if the concentrated
stream has a high heating value and the solvent is inexpensive.
Carbon adsorption may also be an alternative for treating the
permeate stream. The solvent can be collected in a carbon
adsorption unit and recovered by a steam regeneration process.
Overall, a membrane  concentrator can result in cost savings,
improvement in the reduction of emissions and the reduction of
energy requirements for incineration (Hummel and Nelson,
1990).

5.5.3   Range of Effectiveness
  Membrane technology has been reported to be applicable for
low volume, high concentration off-gases (APC, 1991 a). Gas
streams containing 0.05 - 20% organics are suitable for mem-
brane processes. Membrane separation processes are very effi-
cient bulk concentrators. The permeate stream concentration
may be 10 to 50 times the VOCs concentration of the inlet gas
stream.

  The control efficiency of membrane separation technology is
influenced by the following factors:

  1 )  The solvent permeability; and
  2)  The separation factor.

  The permeability is the solvent flux across the membrane. The
permeability of a solvent is related to its diffusivity and solubil-
ity. For organic vapors, the permeabilities usually increase with
concentration and at high pressures (Baker, et al., 1987).

  The separation factor is defined as the degree of concentration
the membrane can achieve and is related to the selectivity of the
membrane. The separation factor refers to the relative perme-
abilities of the solvent and gas. A higher separation factor results
in a more efficient separation process. Both of these parameters
are dependent on operating conditions such as the pressure ratio
(permeate-side pressure/inlet pressure) and the membrane mate-
rial.

  For high removal efficiency, the membrane material should
exhibit high permeability and good selectivity for the solvents to
be  recovered. The membrane should be durable and stable to
 withstand normal wear during operation.
                                                 .
   Membrane performance is determined by the selectivity and
 the pressure (Peinemann, et al., 1 986). The relationship between
 these parameters can be described by the following equation:
       2 7
   where:
a-l
                               C2 + 7 + •
a-l /      a-l
        (Eq. 5-33)
                                             c;
                                             7

                                             a
                                    Permeate concentration of solvent gas;
                                    Feed concentration of solvent gas;
                                    Pressure ratio = total permeate pressure (p") /
                                    total feed pressure (p); and
                                    Selectivity = permeability to solvent / perme-
                                    ability to air.
                                         A graphical representation of the relationship of pressure ratio
                                       and permeate concentration is shown in Figure 5-22. This rela-
                                       tionship is described by Equation 5-33. The relationship simpli-
                                       fies when a »1/7 where the concentration is dependent only on
                                       the pressure ratio. When a « 1/y , the permeate concentration
                                       is determined by the selectivity (Peinemann, et al., 1986).

                                         Permeability data can be found as a function of pressure and
                                       selectivity for various membrane materials and contaminants in
                                       Baker, et al.,  1987. Other references with test data include:
                                       Strathman, et al., 1986 and Peinemann, et al., 1986.

                                       5.8.4   Sizing Criteria
                                         The optimum membrane selectivity is chosen to balance the
                                       capital costs  of the membrane area  and the cost of pumping
                                       energy. Since the solvent flux decreases as the membrane selec-
                                       tivity, increases, the membrane area required to treat a given
                                       amountof solvent increases. The optimum membrane selectivity
                                       is the lowest selectivity that will produce the desired permeate
                                       concentration. The energy requirement for a low selectivity
                                       membrane, however, is greater since a higher volume of gas must
                                       be pumped to meet the permeate requirements (at a fixed perme-
                                       ate pressure). The selection of the membrane must therefore
                                       balance the membrane area and energy requirements (Peinemann,
                                       etal, 1986).

                                         The fundamental mass and energy balance equations govern-
                                       ing the design and performance of a single-stage gas permeation
                                       system is presented by Weller and Steiner, 1950. Further analysis
                                       was performed by Pan and Habgood for the cross-flow pattern,
                                       which applies to the spiral-wound membrane. The simplifying
                                       assumptions for their analyses are: permeabilities of both com-
                                       ponents are constant, negligible pressure drop across flow paths,
                                       and negligible mass transfer resistances except for permeation
                                       through the membrane. The error introduced by assuming con-
                                       stant permeabilities was not found to be excessive in test studies
                                       for most cases (Hummel and Nelson, 1990).

                                         The equations describing membrane performance simplify
                                       considerably as  the feed concentration approaches zero. The
                                       equations are outlined below (Pan and Habgood, 1974):
                                                                              -1
                                                                                     (Eq. 5-34)
                                                                                      xf
                                                                             xf
                                                                                                          (Eq. 5-35)
                                                          69

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                                     Selectivity Controlled
                                   r" Approximation
                                                           Pressure Controlled
                                                           Approximation
                  0.0001
                                      0.001
                                                           0.01
                                                       Pressure Ratio
                    Source: Redrawn from Peinemann. etal., 1986.
Figure 5-22.
  where:
      F
      xf
      x
      y
      7
      a
Calculated permeate solvent concentrations produced by a membrane with a selectivity of 200 and a feed organic vapor
concentration of 0.5%. The three different operating regions for this type of membrane are shown.
                      (i-r)
                                              (Eq.5-36)
      R,
      Fraction permeated (stage cut);
      Mole fraction of solvent in feed gas;
      Mole fraction of solvent in residue off-gas;
      Mole fraction of solvent in permeate;
      Pressure ratio;
      Selectivity (permeability of solvent/perme-
      ability of nitrogen); and
      DimensioBless membrane area.
  These equations are valid for finite l/xf provided that l/xf is
grcaterthan both a and 1/7. An outline of the design procedures
for a spiral-wound membrane module is shown in Figure 5-23.
The membrane area can be calculated from the following equa-
tion (Hummel and Nelson, 1990):
  where:
      S
      d

                                              (Eq.5-37)
      Membrane area, ft2;
      Membrane, thickness, ft;
      Inlet molar flowrate, Ib-mol/hr;
      Feed side pressure, psia; and
                                                       Qa    =     Permeability of sol vent, Ib-molft/hrpsi ft2=
                                                                   (flux)-aYS' (partial pressure).
  The permeability of the solvent, Qa, is determined experimen-
tally from testing at the appropriate operating conditions.

  One consideration that should be taken into account for the
design of amembrane separation unit is the lower explosion limit
(LEL). A membrane preconcentrator handling flammable vapors
in the presence of oxygen (i.e., air) could result in shifting the
concentration within the explosive range (higher than the LEL
value).

5.5.5    Cost Estimating Procedure
  The cost of implementing membrane technology as a control
mechanism for VOCs must be considered with the additional
components needed to comprise the complete system. The mem-
brane usually acts as a concentrator with the permeate stream
requiring further treatment to collect or destroy the contaminants.
As stated before, further treatment may consist of carbon adsorp-
tion (residue off-gas or  permeate stream), condensation,  or
incineration. A more concentrated stream that is to be incinerated
has less of an energy requirement than  a diluted stream. In this
case, incineration will be more economical. S&lvent recovery by
                                                         70

-------
    *Given parameters: Inlet solvent concentration
                    Inlet gas flow rate
                    Membrane selectivity
                    Desired pressure ratio
Select x,
concentration
in residual gas
J .
Calculate F
from Equation
5-33
J
Calculate y
from Equation
5-34


Not
adequate
                                      Check with
                                      desired removal
                                       fficiency
                                            Adequate
                        Valid for 1/x, finite,
                      where 1/x, > a and 1/y
     Design area

    Source: Adapted from Hummel and Nelson, 1990.

Figure 5-23.  Design procedureforaspiral-wound membrane, based
            on Pan and Habgood principles.

condensation may be more feasible for a more concentrated
stream. In the case of recovering the solvent by carbon adsorption
and  steam regeneration, the  addition of the  membrane
preconcentrator was not found to be cost effective even with the
decreased gas flowrate since the carbon required to collect the
solvent remained the same (Hummel and Nelson, 1990).

  The capital cost of the membrane is directly related to its
surface area. The costs of the membrane module and other system
costs associated with the membrane unit are presented in Table
5-17. These costs do not represent any permeate treatment costs.
The system costs were not clearly defined and may include
vacuum pump or compressor costs. Some cost estimates for
designs found in the literature are presented in Table 5-18. Any
specifics on the estimate are provided in the table. The cost of the
system will be very dependent on the treatment requirements of
the permeate and off-gas streams.

  Cost information for capital and operating costs are presented
in Table 5-19. The effects of plant size, membrane flux, and inlet
feed concentration are considered.
  An extensive cost estimate was prepared for the system shown
inFigure 5-21abyHummelandNelson, 1990. The base case was
considered to be recovery of the solvent with a carbon adsorption
unit alone. The cost estimate evaluated the effect of membrane
selectivity, control efficiency, origination of pressure differential
(compressor or vacuum pump), inlet gas flow rate, and solvent
concentration for toluene and CFC-113. The results for a 100
ppmv CFC-113 gas stream at an inlet of 250 acfm are shown in
Figure 5-24. The estimate includes the cost of solvent recovery,
by carbon adsorption and steam regeneration, which as stated
before, does not seem to be  the most economical approach.
Further data can be found in the reference.

5.9    Emerging/Miscellaneous  Controls
  A number of emerging technologies for VOC control have
received attention in recent years. The two emerging technolo-
gies that have been best demonstrated, biofilters and membranes,
have been discussed in detail in earlier subsections. A third
emerging VOC control technology, ultraviolet (UV) photolysis,
is discussed below.

5.9.1   Process Description
  Ultraviolet light technologies have been used for the destruc-
tion of toxic organics in aqueous solutions since about 1988. In
some cases, UV light has been used alone for treatment; in others,
UV light has been used in conjunction with ozone and hydrogen
peroxide, which serve as oxidants (Roy, 1990). Figure 5-23.
Design procedure for a spiral-wound membrane, based on Pan
and Habgood principles.

  Recently, direct UV photolysis of organics has been achieved
experimentally using a broad spectrum of high intensity ultravio-
let light. Experiments have included treatment of water, air, and
soil. The authors have claimed that the direct UV photolysis
process can disintegrate toxic organics into non-toxic byproducts.
Ultraviolet Energy Generators, Inc. (UVERG) have claimed the
Wekhof Direct UV Photolysis Process  to be "both the most
efficient and clean method of organics destruction in water, gas,
and in soil" (Wekhof, 1991).

  Purus, Inc. has also developed a direct UV photolysis process
for on-site cleanup of organic contaminants. The company claims
its  systems, which use xenon UV flashlamps, convert organic
contaminants into harmless byproducts.  Purus, Inc. has adver-
 Table 5-17. Costs for the Membrane Module and Other System
           Costs
 Membrane module  Other system costs  Source of cost information
$231 /m2
54/m2
201 /m2
Best cost estimate
1607m2" •
$231 /m2 Nitto Denko (Japan)
54/m2 (Peinemann, et al., 1986)
252/m2 (Stattman, etal., 1986)
60/m2b
 •  Cost basis for membrane, an approximate average of the cost data.
 "  Cost basis for other system costs was reduced to S60/m2 since cost data from
   other sources included equipment not within the membrane system.

 Adapted from Hummel and Nelson, 1990.
                                                          71

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 Tabla 5-18. Design Specifications and Costs for Components of Membrane Control Systems
 Case
System
                                                 Specifics
                                                             Cost ($)
                 Source
1 Vacuum pump and blower







2 Vacuum pump and blower; carbon
adsorption recovery unit


3 Compressor; carbon adsorption



4 Vacuum pump






Inlet cone.
Permeate cone..
Residue cone.
Feed flow
Volume recovered
Mem area
Mem. selectivity
Pressure ratio
Inlet cone.
Removal eff.
Feed flow
Inlet cone.

Removal eff
Feed flow
Permeate cone.
Inlet cone.
Feed flow
Volume recovered
Mem. area
Mem. solvent flow

0.5 vol%
4.4 vol%
0.1 vol%
1400 scfm
1000 I/day
1020m2
150
0.05
• 100ppm
CFC-113
• 57%
2500 CFM
1 000 ppm
CFC-113
57%
2500 CFM,
50 Wt%
0.5 sol%
1 0,000 sofm
6 l/min
1700 m*
5 l/m2 day

Membrane
Other system
Blower
Pump

Total









Membrane
System
Pump
Install &
other

Total
54,700
54,700
40,200
295,000

444,600


736,500


437,500



91,100
91,100
13,400
20,000


215,600
Peinemann, et al., 1986







Hummel & Nelson, 1990


Hummel & Nelson, 1990



Baker, etal., 1985'






 tiscd a commercial system for treatment of contaminated air
 emissions by UV photolysis.

   A flow diagram for a direct UV photolysis system is shown in
 Figure 5-25. In a typical direct UV photolysis system, contami-
 nated air enters one or more processing chambers in which the
 contaminants are subjected to a broad spectrum of UV light
 emitted by UV flashlamps. The organic contaminants absorb
 varying wavelengths of UV light. The absorbed energy causes
 the bonds of the organic molecules to break apart. Under ideal
 conditions, the carbon atoms of the molecules, along with oxygen
 present in the air, may simply form carbon dioxide. If analysis
 indicates sufficient removal of  contaminants, the treated air
 stream may be released to the atmosphere (Purus, 1991).

 5.93  Applicability to Remediation Technologies
   UV photolysis may be effective in destroying volatile organic
 compounds (VOCs) in contaminated air streams. Contaminants
 that could be removed from air streams by UV photolysis may
 include volatile chlorinated organic compounds (e.g., trichloro-
 cthylenc (TCE) and methylene chloride) and volatile organic
 compounds present in gasoline and petroleum products (e.g.,
 benzene and toluene).

  UV photolysis has  not  been reported in the literature as a
control technology for air emissions at Superfund sites. This
technology may be appropriate to control emissions of toxic
organic compounds released by  wastewater and groundwater
treatment technologies such as  biological treatment and air
stripping. It also may be appropriate in treating air emissions
                                             Table 5-19. Effect of Plant Size, Membrane Flux, and Feed Concen-
                                                       tration on Capital and Operating Costs for Membrane
                                                       Systems ,
Parameter
Plant size (scfm)
10,000°
5,000
2,000
500

Area (m 2)
1,700
850
340
85
Capital
costs ($) •

215,800
31,500
71 ,400
30,700
Operating
costs ($) b

67,100
33,600
13,400
3,350
                                            Membrane flux

                                                  (l/m2 day)
                                                    10.0
                                                    5.0c
                                                     2.5
                                                     1.0
Area (m 2)
   850
  1,700
  3,800
  8,500
131,500
215,800
362,600
759,200
                                            Feed concentration    Membrane flux
 52,000
 67,100
 97,600
188,800
(vol %)
0.5"
0.25
0.1
0.05
(l/m2 day)
5.0 215,800 '
2.5 215,800
1.0 215,800
0.5 215,800

67,100
48,800
37,800
34,000
                                            •  Membrane module costs assumed to increase directly in proportion to
                                              membrane area. Others increase in proportion to the square root of plant size.
                                            "  Operating costs are assumed to be proportional to the solvent (low through
                                              the plant. Includes module replacements costs (3-year lifetime).
                                            c  Base case.

                                            Source: Adapted from Baker, et al, 1985.
                                                          72

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                   1.0
                   0.8
               I   0.6
               O   0.4

               I


                   0.2




                   0.0
Selectivity-200, Vacuum Pump
Selectivity-200, Compressor
Selectivity-20, Vacuum Pump
Selectivity-20, Compressor
Selectivity-5, Vacuum Pump
Selectivity-5, Compressor
Carbon Adsorption
                      50
   60
  70                 80
Overall Control Efficiency (%)
                                                                                             90
100
Figure 5-24. Capital cost comparison (250 acfm, 100 ppm, CFC-113 feed).
                                        UV Flashlamp
                                                                          Treated Air
                                                                UV Processing
                                                                  Chamber
                                                                UV Processing
                                                                   Chamber
                                                    Contaminated Air
Figure 5-25. Schematic of direct UV photolysis.
                                                                73

-------
 from in situ remediation of soil by vacuum extraction. UV
 photolysis would have the advantage of destroy ing toxic organic
 compounds rather than transferring the compounds to another
 medium (e.g., activated carbon).

 5.93    Range of Effectiveness
  Since studies examining the, destruction of organics through
 treatment of contaminated ajr streams by UV photolysis have
 been limited, the range of conditions over which this treatment
 may be effective is unclear. One study indicated that the concen-
 tration of TCE in an ajr stream was reduced by UV photolysis
 from 300,000 ppb to 100 ppb for a residence time of approxi-
 mately 3 seconds  (Purus, 1991). Without additional data, the
 general effectiveness of this technology for Superfund applica-
 tions can not be determined.

 5.9 A    Sizing Criteria
  No specific sizing criteria are available for treating air emis-
 sions by UV photolysis. The size of a UV photolysis system will
 depend primarily on the following parameters:

  1 )  The flow rate of the contaminated air stream;
  2)  The concentrations of destructible compounds in the air
      stream; and
  3)  The refractoriness of the compounds.

  Pilot UV photolysis tests would be performed on a sample air
 stream to determine the appropriate size for a full-scale system.
        Cost Estimating Procedure
  No cost estimates have been reported in the literature for
vapor-phase treatment using full-scale direct UV photolysis
units. Although Wekhof (1991) estimates costs for treatment of
wastewater and soil by UV photolysis, the costs for treatment of
air streams is not estimated. Costs for treatment of contami-
nated air emissions by the Purus, Inc. direct UV photolysis
process are not available.

5.10   References
  The Air Pollution Consultant. VOC Emission Control During
      Site Remediation. McCoy and Associates, Lakewood,
      CO. September/October 1 99 1 a.

  The AirPollution Consultant. Biofiltration Shows Potential as
      an AirPollution Control Technology. McCoy and Asso-
      ciates, Lakewood, CO. November/December 1991b.

  Amcec Corp. Productbrochurefor activated carbon. Oakbrook,
      EL. 1991.

  Baker, R.W., I. Blume, V. Helm, A. Kahn, J. Maguire, and N.
      Yoshioka. Membrane Research in Energy and Solvent
      Recovery from Industrial Effluent Streams. DOE Report
      DE84016819. DOE-INEL, Idaho Falls, ID. 1984.

  Baker, R.W., K. Hibino,  J. Mohr and T. Kuroda. Membrane
      Research in Energy and Sol vent Recovery from Industrial
      Effluent Streams. DOE/ID/12379-T2, report for the pe-
      riod 5/1 1/83 - 31/1/85, prepared by Membrane Technol-
     ogy & Research , Inc. for the U.S. DOE. DOE-INEL,
     Idaho Falls, ID. 1985.

 Baker, R.W., N. Yoshioka, J.M. Mohr and A. J. Khan. Sepa-
     ration of Organic Vapors from Air. J. Membrane Science',
     Vol.31,pp259-271.1987.

 Chu, RJ. VOC Emission Control Technologies for Site
     Remediation. Proceedings of National Research & De-
     velopment Conference on the Control of Hazardous
     Materials, Anaheim, CA. HMCRI Publications Dept,,
     Greenbelt, MD. 1991.

 Cooper, C. and F. Alley. Air Pollution Control: A Design
     Approach. Waveland Press, Prospect Heights, IL.  1986.

 CRC Handbook of Chemistry and Physics, CRC Press, Boca
     Raton, FL. 1992.

 Danielson, J.A., ed. Air Pollution Engineering Manual. Na-
     tional Center for Air Pollution Control, U.S. Department
     of Health, Education and Welfare, Cincinnati, OH. 1967.

 DCI. Product brochure for activated carbon. Indianapolis, IN.
     1991.

 Eklund, B.M., P. Thompson, A. Ihglis, and W. Dulaney. Air
     Emissions from the Treatment of Soils Contaminated with
     Petroleum Fuels and Other Substances. EFA-600/R-92-
     124. July 1992.

 The Hazardous Waste Consultant. McCoy and Associates,
     Lakewood, CO. Vol. 6, No. 5.1988.

 Hesketh, H.E. AirPollution Control: Traditional and Hazard-
     ous Pollutants. Technomic Publishing Co., Lancaster, PA.
     1991.

 Hummel, K.E. and T.P. Nelson. Test and Evaluation of a
     Polymer Membrane Preconcentrator. EPA 600/2-90-016.
     April 1990.

 Katari, V.W., W. Vatavuk and A.H. Wehe. Incineration Tech-
     niques for Control of Volatile Organic Compound Emis-
     sions, Part I: Fundamentals and Process Design Consider-
     ations. JAPCA Vol. 37, No. 1, Pittsburgh, PA. 1987a.

 Katari, V.W., W. Vatavuk and A.H. Wehe. Incineration Tech-
    niques for Control of Volatile Organic Compound Emis-
    sions, Part II: Capital and Annual Operating Costs. JAPCA
    Vol. 37, No. 2, Pittsburgh, PA. 1987b.

Kern, D.Q. Process Heat Transfer. McGraw-Hill, New York,
    NY. 1950.

Kittrell,  J., C. Quinlan, and J. Eldridge.  Direct Catalytic
    Oxidation of Halogenated Hydrocarbons. JAWMA, Vol.
    41, No. 8, ppl 129-1133.1991.
                                                      74

-------
Leson, G. and A. Winer. Biofiltration: An Innovative Air
    Pollution Control Technology for VOC Emissions.
    JAWMA Vol. 41, No. 8, Pittsburgh, PA. August 1991.

Ludwig, E.E. Applied Process Design for Chemical and Petro-
    chemical Plants, Vol. III. Gulf Pub., Houston, TX. 1965.

Marzone, R.R. and D.W. Oakes, Profitably Recycling Sol-
    vents from Process Systems. Pollution Eng., Vol. 5, No.
    10, pp23-24. New York, NY. 1973.

Miller, D. and L. Canter. Control of Aromatic Waste Air
    Streams by Soil Bioreactors. Env. Progress, Vol. 10, No.
    4, pp300-306. New York, NY. November 1991.

Millican, R. of SCAQMD; Pers. comm. with J. Curtis, Camp,
    Dresser & McKee. Boston, MA. 1989.

Pan, C. Y. and H.W. Habgood. An Analysis of the Single Stage
    Gaseous Permeation Process. Ind. Eng. Chem. Fundam.,
    Vol. 13,pp323-331.1974.

Pedersen, T. and J. Curtis. Soil Vapor Extraction Technology:
    Reference Handbook. EPA/540/2-91/003 (NTIS PB91-
    168476). February 1991.

Peinemann, K.V., J.M. Mohr and R.W. Baker. Separation of
    Organic Vapors from Air. AIChE Symp. Ser., Vol. 82, No.
    250, p!9. New York, NY. 1986.

Perry, R.H. and C.H. Chilton, eds. Chemical Engineering
    Handbook, 5th Ed. McGraw-Hill, New York, NY. 1973.

Purus, Inc. On-Site Organic Contaminant Destruction with
    Advanced Ultraviolet Flashlamps. Product brochure for
    UV lamps. Purus, San Jose, CA. 1991.

Roy, K.A. Hazmat World. Vol. 3, No. 5. From a series on UV-
    oxidation technologies. Tower-Borner  Publishing, Glen
  .  Ellyn,IL. 1990.

RSI. Personal communication from Jim Sadler to Charles
    Albert of Radian Corporation. Remediation Services In-
    ternational,  Oxnard, CA. 199 la.

RSI. Product brochure - the S.A.V.E.  System. Remediation
    Services International, Oxnard, CA. 1991b.
Shareef, G.S. Personal communication from Gunseli Shareef
    to Bart Eklund of Radian Corporation. 1991.

Smith,  J.M. and M.C. VanNess. Introduction to Chemical
    Engineering Thermodynamics, 3rd ed. McGraw-Hill, New
    York, NY. 1975.

Strathman, H., C. Bell and K. Kimmerle. Development of a
    Synthetic Membrane for Gas and Vapor Separation. Pure
    and Applied Chem. Vol. 50, No. 12. Blackwell Scientific
    Publications, Ltd. Oxford, England. 1986.

U.S. EPA. Handbook: Control Technologies for Hazardous
    Air Pollutants EPA/625/6-91/014. Cincinnati, OH. June
    1991.

U.S. EPA. Destruction of Chlorinated Hydrocarbons by Cata-
  ,  lytic Oxidation. EPA/600/2-86/079. RTP, NC. 1986.

U.S. EPA. Soil Vapor Extraction Technology VOC Control
    Technology Assessment. EPA/450/4-89/017 (NTIS PB90-
    216995). RTP, NC. September 1989.

U.S. EPA (W.M. Vatavuk). OAQPS Control CostManual (4th
    Edition) EPA/450/3-90/006 (NTIS PB90-169954). Janu-
    ary 1990.

van der Vaart, D.R., W.M. Vatavuk, A.H. Wehe. The Control
    Efficiencies of Thermal and Catalytic Incineration for the
    Control of Volatile Organic Compounds. JAWMA Vol.
    41, No. 4. Pittsburgh, PA. 1991.

Vatavuk, W.M. Estimating Costs of Air Pollution Control.
    Lewis Publishers. Chelsea, MI. 1990.

VR Systems. Product brochure - Soil Venting Cost Compari-
    son. Anaheim, CA. 1991.

Walas, S.M. Chemical Process Equipment Selection and De-
    sign. Butterworth Publishers, Boston, MA. 1988.

Wekhof, A. Treatment of Contaminated Water, Air, and Soil
    with UV Flashlamps. Env. Progress, Vol. 10, No. 4. New
    York, NY. 1991.

Weller, S. and W.A. Steiner. Fractional Permeation Through
    Membranes.  Chem. Eng. Progress, Vol. 46, pp585-591.
    New York, NY. 1950.
                                                     75

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                                                 Chapter 6
                    Point Source Controls for Particulate Matter, Metals,
                                Acid Gases, and Dioxins and Furans
  Information is presented in this chapter about various control
technologies whose primary use is to control emissions of par-
ticulate matter (PM), metals, acid gases, and dioxins and furans.
Control technologies addressed in this chapter are fabric filters
(i.e., baghouses), wet and dry electrostatic precipitators (ESPs),
wet scrubbers, dry scrubbers, operational controls, and miscella-
neous technologies such as HEPA filters. Quench chambers,
cyclones, and venturi scrubbers are covered under wet and dry
scrubbing. The discussion for each control technology includes
a process description, applicability for remediation technologies,
range of effectiveness, sizing criteria, and cost information.

  The Superfund applications of the control technologies cov-
ered in this section are limited almost exclusively to incineration
and  thermal desorption. The controls may each be  somewhat
effective at removing paniculate matter, metals, acid gases, and
dioxins. They tend to be used in series so that the overall removal
efficiency for the train of air pollution controls (APCs) meets
design specifications. For example, an on-site incinerator may
have a series of control  devices: 1) cyclone,  quench tower,
baghouse, and wet scrubber; or 2) spray tower (quencher) and
baghouse; or 3) cyclone, water quench, and packed tower (HMCRI,
1991). Many other combinations also may be used.

6.1    Fabric Filters
6J.I   Process Description
  Fabric filters are a type of air pollution control device designed
for controlling particulate matter emissions from point sources.
A typical fabric filter consists of one or more isolated compart-
ments containing rows of fabric bags or tubes. In a fabric filter,
particle-laden gas passes  up along the surface of the bags then
radially through the fabric. Particles are retained on the upstream
face of the bags, while the clean gas stream is vented to the
atmosphere.  The filter is operated cyclically so that it alternates
between long periods of filtering and short periods of cleaning.
During cleaning, dust that has accumulated on the bags is
removed from the fabric  surface and deposited in a hopper for
 subsequent disposal.

   Fabric filters will collectparticle sizes ranging from submicron
 to several hundred microns in diameter at efficiencies generally
 in excess of 99 percent. Gas temperatures up to about 500°F, with
 surges to approximately 550°F can be accommodated routinely.
 Most of the energy used to operate a fabric filter system appears
 as pressure drop across the bags and associated hardware and
ducting. Typical values of pressure drop range from about 5 to 20
inches of water column.

  Important process variables in a fabric filter system include
particle characteristics, gas characteristics, and fabric properties.
The most important design parameter is the air-to-cloth ratio, and
the usual operating parameter of interest is the pressure drop
across the  filter system. Baghouses  can be operated on an
intermittent or continuous basis. In the latter case the system is
usually divided into sections, so bags can be taken off-line for
cleaning. When cleaning must be done off-line the system tends
to be more expensive since extra cloth area (capacity) is required.

  Fabric filters often are categorized by the method used to clean
the dust-cake off of the filter. Using this method of categoriza-
tion,  three  common  types of filters are: 1) shaker filters, 2)
reverse-air filters, and 3) pulse-jet filters. The process flow
diagram for a typical shaker filter is shown in Figure 6-1.

  In a shaker filter, the  bags are hung on a framework that is
oscillated by a motor controlled timer. In this type of system the
baghouse usually is divided into several compartments. The flow
of gas to each compartment periodically is interrupted and the
bags are shaken to remove the collected dust. The shaking action
produces more wear on the bags than other cleaning methods. For
this reason, the bags used in this type of filter are usually heavier
and made from durable fabrics.

   In the second type of fabric filter, reverse air filters, gas flow
to the bags is stopped in the compartment being cleaned, and a
reverse flow of air is directed through the bags. The advantage of
this approach is that is "gentler" than shaking, which allows the
use of more fragile or lightweight bags.

   The third type of baghouse, pulse-jet fabric filters, are by far
the most common type for Superfund applications. In this type of
 system a blast of compressed air is used to expand the bag and
 dislodge the collected particles. One advantage of pulse jetfabric
 filters is that bags can be cleaned on line, which means that fewer
 bags (less  capacity) are  required for a given application.

 6.1.2   Applicability  to Remediation Technologies
   Three factors that affect the feasibility of using a baghouse to
 control particulate emissions are the flue gas temperature, the gas
 stream composition, and the particle characteristics. The tem-
                                                          77

-------
                            Shaker
                        mechanism
                 Clean
                air out
                   Dirty
                   air in
Figure 6-1. Fabric filter process flow diagram.
                                                              78

-------
perature of the waste gas stream to be cleaned must be above the
dewpoint of any condensibles in the stream, but below the
maximum temperature for the fabric. Condensibles will wet the
filter cake and make cleaning very difficult, as well as increase
the pressure'drop across the filters. Other gas stream and particle
characteristics also must be considered in since fabric filters may
not be suitable for certain types of gas streams or particles. For
example, a fabric filter may not be suitable for an application in
which the waste gas particulate matter contains a significant
fraction of acid mist. Also, "sticky" or adhering particles might
preclude the use of a baghouse. For baghouses operated in cold
climates that use compressed air, shelters should be constructed
around the equipment to prevent freezing of condensed moisture
in the air compressor lines.

   Since baghouses are used only as particulate controls on dry
waste gases, their use as controls for Superfund site remediations
are limited to cases where incineration or thermal desorption are
being used to remediate the site. Baghouses frequently are used
in conjunction with dry scrubbers. Baghouses are also highly
effective for the removal of heavy metals.

6.1.3    Range of Effectiveness
   A well designed fabric filter can achieve collection efficiencies
in excess of 99 percent, although optimal performance of the
system may not occur for a number of cleaning cycles as the new
filter material is "broken in." The fabric filter collection effi-
ciency is related to the pressure drop across the system, compo-
nent life, filter fabric, cleaning method and frequency, and the
air-to-cloth (A/C) ratio.

   Modifications to improve performance include changing the
A/C ratio, using a different fabric, or replacing worn or leaking
filter bags.  Collection efficiency can also be improved by de-
creasing the frequency of cleaning or allowing the system to
operate over a greater pressure drop before cleaning is initiated.

 6.1.4   Sizing Criteria
   The key  parameter in fabric filter design is the air-to-cloth
 ratio. The A/C ratio, or filtration velocity, is a defined as  the
 actual volumetric flow rate (acfm) divided by the total active, or
 net, fabric area. Selection of an appropriate range of A/C ratios
 is not based on any theoretical or empirical relationship, but
 rather is based on industry and  fabric filter vendor experience
 from actual installations. A ratio is usually recommended for a
 specific dust and a specific cleaning method.

   The ranges of recommended A/C ratios for many different
 dusts and fumes are summarized in Table 6-1. A conservative
 estimate for the A/C ratio of particulate matter generated in
 Superfund  remediations would be 3.0 for woven fabric and 10.0
 for a felt fabric. The A/C ratio and the emission stream flowrate
 (Q) can be used to calculate the net cloth  area (Anc) as shown
 below in Equation 6-1:
Table 6-1.  Air-To-Cloth Ratios
                          A/C ratio
                                                  (Eq.6-1)
Shaker/woven Pulse jet/felt
Dust ' reverse-air/woven ' reverse-air felt
Alumina
Asbestos
Bauxite
Carbon black
Coal
Cement
Fly ash
Graphite
Gypsum
Lime
Limestone
Source: U.S. EPA, 1 990.
• A
Q"- =
A/C ratio =
2.5
3.0
2.5
1.5
2.5
2.0
2.5
2.0
2.0
2.5
2.7

Net cloth area, ft2;
8
10
8
5
8
8
5
5
10
10
8


Waste gas flowrate, acfm; and
Air-to-cloth ratio, acfm/ft2.

   The net cloth area is the area that must be active at any point in
 time; it is not the total required cloth area. The gross cloth area
 (Atc) is the total cloth area in the fabric filter, including that which
 is out of service at any point for cleaning or maintenance. Given
 the net cloth area, an estimate of the gross cloth area can be made
 using factors given in Table 6-2 and Equation 6-2 shown below:
                       A  -C
                                              (Eq.6-2)
where:

    £
                 Total cloth area, ft2;
                 Net cloth area, ft2; and
                 Design factor based on size (Table 6-2),
                 dimensionless.
 6.1.5   Cost Estimating Procedure
   The equipment costs for a fabric filter system can generally be
 estimated two ways: 1) by obtaining quotations from vendors, or
 2) by using generalized cost correlations available in the litera-
 ture.
 Table 6-2.  Approximate Guide to Estimate Gross Cloth Area
   Net cloth area (ft2)
                                 Gross cloth area (ft2)
1-4,000
4,001-12,000
12,001-24,000
24,001-36,000
36,001-48,000
48,001-60,000
60,001-72,000
72,001-84,000
84,001-96,000
96,001-108,000
108,001-132,000
132,001-180,000
above 180,001
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
2.0
1.5
1.25
1.17
1.125
1.11
1.10
1.09
1.08
1.07
1.06
1.05
1.04
   where:
  Source: U.S. EPA, 1990.
                                                           79

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    The purchased cost of a fabric filter system will vary widely
  depending on several design factors. Consequently, caution is
  required when using generalized cost correlations. Among the
  factors that influence the purchased cost of a baghouse are the
  supplier's design experience, materials of construction, instru-
  mentation, the method of cleaning, and the nature of the applica-
  tion (i.e., Are there any factors, such  as "sticky" particles, that
  make the application difficult?).

    Baghouse equipment costs as a function of gross cloth area for
  cleaning systems  are presented in  Figure 6-2. This figure  is
  adapted from U.S.  EPA, 1990. The equipment costs  given
  represent the cost for a fabric filter system without bags. A rough
  estimate of the bag cost can be made by assuming $1.00/ft2. A
  moreaccurateestimaterequiresknowledgeof the fabric type and
  the cleaning technique (see U.S. EPA, 1991).

   The installation and engineering costs for a fabric filter system
  can be estimated using the factor method presented in Table 6-3.

  6.2    Electrostatic Precipitators
  62.1   Process Description
   Electrostatic precipitators (ESPs) are point-source particulate
  matter control devices that use an electrostatic field to charge
  particulate matter contained  in a gas stream. The charged par-
  ticles then migrate to a grounded collecting surface. The col-
  lected particles are dislodged from the collector surface periodi-
                                                 cally by vibrating or rapping the collector surface, and subse-
                                                 quently are collected in a hopper at the bottom of the ESP.

                                                   A typical dry electrostatic precipitator is shown in Figure 6-3.
                                                 The major components of the ESP include: gas inlet, discharge
                                                 electrodes, collecting electrodes, rappers, cable from rectifier,
                                                 wire-tensioning weights, hopper baffles, hopper, shell, and sup-
                                                 port frame. The gas enters the ESP and passes through a series of
                                                 discharge electrodes. The discharge electrode is usually a small
                                                 diameter wire and a plate or cylinder, which together create a
                                                 nonuniform electric field. The electrodes typically are negatively
                                                 charged and create a corona around  the electrode. A negative
                                                 charge is induced in the particle matter as it passes through the
                                                 corona. A grounded surface, or collectorelectrode, surrounds the
                                                 discharge electrode. The charged particle collects on the collect-
                                                 ing electrode, which is typically aplate. The charged particles are
                                                 neutralized by the collecting electrode. Common types of collect-
                                                 ing electrodes used in ESPs are presented in Figure 6-4. The
                                                 particulate matter is removed from the plate by  rappers.  This
                                                 device strikes the collecting electrode to dislodge the collected
                                                 particles, which then fall by gravity into a hopper. The intensity,
                                                 frequency and  number of blows is determined as part of the
                                                 design. Removal of the particles is essential to ensure that the
                                                 particulates collected do not act as an insulator, thereby decreas-
                                                 ing the ability  of the ESP to function. Reentrainment of the
                                                 particles must be minimized to ensure adequate control  effi-
                                                 ciency. The particles are collected in the hopper and can be
                                                 disposed when necessary.
    900


    800


    700


5  600
V"

1  500
a.


I  40°
                  300
                  200
                  100
                                  Note: Costs are without! bags, insulation, or
                                       stainless steel upgrade.
                                                      	 Pulse Jet
                                                      	 Reverse Air Row

                                                      	Mechanical Shaker
                                                              _L
                                         20         30        40         50        60

                                                           Gross Cloth Area, Ato (1000 ft2)
                                                                               70
                                                                                         80
         Source: Adapted from U.S. EPA, 1990.

Figure e-2. Fabric filter equipment cost
                                                          80

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Table 6-3. Cost Factors for Fabric Filter Installation and Engineering
                     Cost item
                                                                                          Cost factor (fraction of indicated cost)
Direct costs
    Purchased equipment
    Fabric filter w/bags
    Instrumentation
    Taxes
    Freight
     Installation
     Foundations and supports
     Erection and handling
     Electrical   '
     Piping
     Painting
     Insulation
     Site preparation
     Building/construction
 Indirect costs

     Engineering and supervision
     Construction/field expenses
     Construction fee
     Start-up
     Performance test
     Contingency
                                                  Total Equipment Costs:
                                                  Total Installation Costs:
                                            Total Direct Costs (TEC + TIC):
                                                      Total Indirect Costs:
                  Total Direct + Total Indirect Costs = Total Capital Investment:
                                                      A
                                                  0.10 A
                                                  0.03 A
                                                  0.05 A

                                               B = 1.18A
                                                  0.04 B
                                                  0.50 B
                                                  0.08 B
                                                  0.01 B
                                                  0.02 B
                                                  0.07 B
                                                     SP
                                                   Bldg.

                                       0.72 B + SP + Bldg.
                                       1.72 B + SP + Bldg.
                                                  0.1 OB
                                                  0.20 B
                                                  0.1 OB
                                                  0.01 B
                                                  0.01 B
                                                  0.03 B

                                                  0.45 B
                                       2.17 B + SP + Bldg.
 Source: U.S. EPA, 1990.
   Several types of ESPs are commonly used. Plate-wire precipi-
 tators are used to treat high volumes of gases. For example, flat
 plate ESPs can handle flow rates of 100,000 to 200,000 cfm. At
 Superfund sites, weighted-wire ESPs are the most commonly
 used type of ESP (Donnelly, 1991). Another commonly used
 type of ESP is a tubular ESP.

   An alternative to "rapping" for removing  the particles is
 washing the sides of the ESP with water, either intermittently or
 continuously, i.e., a wet electrostatic precipitator. In wet ESPs,
 water  is sprayed on the incoming gas stream  to achieve a
 saturated condition.

   The electric charge is transferred to liquid droplets. The liquid
 containing the particles becomes charged, is collected, and
 thereby washes away from the gas stream. A potential disadvan-
 tage to wet ESPs is that the collected waste stream may present
 a solids and liquid handling problem.

   Another operating arrangement is the two-stage ESP. In this
 system, the gas stream passes through a corona discharge prior to
 entering a separate collection area. The two-stage ESPs  are
 usually used for gas flow rates less than 50,000 cfm.
  The most important variable to be considered in the design of
an ESP is the collection plate area. Collection plate area is a
function of the desired collection efficiency, gas stream flowrate,
and particle drift velocity. The particle drift velocity is a compli-
cated function of particle size, gas velocity, gas temperature,
particle resistivity, particle agglomerization, and the physical
and chemical properties of the paniculate matter. Unfortunately,
there are no easy empirical approaches to calculate drift velocity
from these variables. Vendors typically rely on experience to
estimate pressure drop.

6.2.2   Applicability to Remediation Technology
  Electrostatic precipitators are very efficient paniculate matter
control devices. Efficiencies of 99 percent or more are attainable.
ESPs are capable of removing very small particulates  (0.01
micron up to 70 micron diameter particles) and can treat dry or
wet particles (Brunner, 1984). Wet ESPs typically are not af-
fected by the insulation effect and are able to collect gaseous or
condensible contaminants along with the particulate matter. The
use of ESP technology incurs a relatively high capital cost and the
control efficiency is sensitive to variable gas stream conditions,
such as dust loading, flow rate, and temperature. Another limita-
tion for ESPs is the type of particles that can be removed, which
                                                             81

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                                         Collector
                                         Plate
                          Dirty
                          Gas In
                                         Particle
                                         Layer on
                                         Collector
                                         Surface
                                                                                                       Clean
                                                                                                       Gas Out
                                                                   Collected
                                                                 Particles Out
 Figure 6-3.  Electrostatic preclpltator process flow diagram.
••<>••••••
Gas I-K '
Flow H'
Rod Curtain

r r "] i r
L L J J L
Gas pK

Common Plate
AAAAA
Gas r-K j '
Flow '-v'
AAAAA
Zig-Zag Plate


Gas p\
Flow Lv? .
Dual Plates

!f : !f

^^
Gas
Flow
Vertical Gas
Flow Plates
      Source: Redrawn from Danielson, 1973.

Figure 6-4. Special collecting eleictrodes used In electrostatic precipltators.
                                                                 82

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is dependent on the resistivity of the particles. Wet ESPs have
some added disadvantages: corrosion potential and wastewater
treatment.

  Since ESPs are used only as paniculate controls on point
sources, their use as controls for Superfund site remediations is
usually limited to cases where incineration or thermal desorption
is used to clean up the site.

6.2.3   Range of Effectiveness
  ESPs control particulates effectively down to the sub-micron
range. The key parameters affecting the control efficiency of
ESPs include the following:

  • Particulate composition, density, and resistivity;
  • Gas stream temperature and pressure;
  • Gas stream velocity;
  • Power; and
  • Plate area.

  The particulate composition, density, and resistivity affect the
particle drift velocity. In turn, the drift velocity, along with the
                           control efficiency and gas flow rate, are used to determine the
                           collection plate area, which ultimately determines the cost of the
                           ESP. The relationship of the specific collection area (collector
                           area normalized by volumetric flow rate) and control efficiency
                           is shown in Figure 6-5.

                              The resistivity is important for determining the ability of an
                           ESP to collect a specific material. The optimum resistivity range
                           for adequate control efficiency is 104 to 1010 ohm-cm. Particles
                           with low resistivities impose special considerations on  ESP
                           design. These type of particles (resistivities from 104to 107 ohm-
                           cm) are difficult to collect in an ESP because the particles tend to
                           lose their charge and drop off the collector plate and become
                           reentrained in the gas stream. In such cases, specially designed
                           collecting plates or coatings may be used to reduce reentrainment.
                           Particles with high resistivities  can also cause ESP operating
                           difficulties. High resistivity particles accumulate on the collec-
                           tion plates and insulate the collection plate, thus reducing the
                           attraction between particles and collecting plate. In these cases,
                           using an oversized ESP and more frequent cleaning or rapping of
                           the collector plates may be necessary.
                 99.9
                   99
                CD
               I
               5
                    90
                        w = Drift Velocity


                                    X
                  w = 10 cm/sec
~f
L-

                                                                  -e—e-
                                                                   -G-
                                                                                 -e-
                                                                               -e-
                                                                               Q
                                             o
                                             O
                                                                                                    -o
                                                                                       w = 4 cm/sec
                                                                                   X
                                                                               A Design

                                                                               O Test
0.1
                                                0.2           0.3           0.4

                                                  Specific Collection Surface Area, A
                                                                                        0.5
                                                                                                      0.6
         Source: Oglesby and Nichols, 1970.

  Figure 6-5. Relationship between collection efficiency and specific collection area for municipal incinerators.


                                                            83

-------
          I
          CD
               65
              55
              45
              35
              25
                80
Temperature
                                        Relative Humidity
                                84
                                                 88               92
                                                Precipitator Efficiency (%)
                                           96
                                                                                                      145
                                                                                                      140
                                                                                                           IT
                                                                                                           O	
                                                                                                           ¥
                                                              135   o
                                                                    2
                                                                                                      130
                                                                                                     125
                                                           100
     Source: Redrawn from Brunner, 1984.
 Figure 6-6. Effect of gas stream temperature and humidity on collection efficiency for a specific ESP.
   An alternative to oversizing the ESP is the use of conditioning
 agents to reduce theresisitivity of the particles. The resistivity is
 dependent on temperature, moisture conditions in the gas, and the
 concentration of electronegative gases (e.g., SO2). The effect of
 temperature and humidity on the precipitator efficiency for a
 given ESP installation is shown in Figure 6-6.

   The gasvelocityshouldbe maintained within an optimal range
 to ensure that continuous reenlrainment, which usually occurs at
 high gas velocities, is not a large risk. The optimum range is
 usually 2-4 ft/sec (Brunner,  1984). The amount of delivered
 power also affects the control efficiency, since thebestcollection
 usually occurs at the highest  electric field, i.e., the  highest
 voltage. Too high a voltage, however, may result in discharging
 from the wires to the plates and thereby decrease RE and increase
powercosts. The relationship of control efficiency and delivered
power for municipal incinerators is shown in Figure 6-7.

62 A   Sizing Criteria
  Typical ESP design criteria are presented in Table 6-4. As
indicated, the key design parameters include:

  • Paniculate composition, density, and resistivity;
  • Flue gas temperature and moisture;
  * Inlet particulate loading and collection efficiency;
  * Specific collection area;
                           Number of fields;
                           Flue gas velocity;
                           Collector plate spacing;
                           Rapping frequency and intensity; and
                           Transformer rectifier power levels.

                         The most important front end design parameter is the specific
                       collection area (SCA). The SCA can be estimated  from the
                       following equation (Vatavuk, 1990):
                                               -In i - i*
                                        SCA=    ^   100)
                                                   W.
                                                                        (Eq.6-3)
                       Table 6-4.  Typical Design Parameters for Electrostatic Precipita-
                                 tors
                               Parameters
                                                                  Value
                       Particulate loading (gr/acf)
                       Required efficiency (%)
                       Number of sections
                       SCA(ft2/1000acfm)
                       Average secondary voltage (kv)
                       Average secondary current
                         (mA/IOOOft3)
                       Gas velocity (ft/sec)
 0.5-5.0
98.0-99.9
   2-4
350-500
 35-55
 30-50

 3.0-3.5
                                                              Source: U.S. EPA, 1990.
                                                          84

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                    99.9
                      99
                                          z
                  
-------
 Tablo 6-5. ESP Drift Velocities for Incinerator Fly Ash in Units of
           cm/sec
 Particle source
                                    Design efficiency
ESP unit
                               95
                   99
                                            99.5    99.9
 Incinerator fly ash •  Plate-wire   15.3   11.4   10.6    9.4
 Incinerator fly ash"  Flat-plate   252.   16.9   21.1    18.3
 •  200* F; no back corona
 *  250* F; no back corona
 Source: Adapted from U.S. EPA, 1930.

 systems, which could be typical at Superfund sites. These sys-
 tems are usually packaged modules that are sized and sold on the
 basis of waste gas volumetric flow rate. Further design informa-
 tion can be found in Vatavuk, 1990 and Oglesby and Nichols,
 1970. A secondary consideration in the design of an ESP is the
 material of construction. For example, stainless steel must be
 used for corrosive applications.

   Often the ESP design is inadequate and once the system is
 installed optimization in the field may be required. Basic design
 problems include undersized equipment, reentrainment, or high
 resistivity particles. Agents can be injected to the system to alter
 the resistivity to achieve higher removal efficiencies. The ESP
 can also be manipulated effectively if performance is monitored
 closely. The following measurements should be taken periodi-
 cally to ensure the collection efficiency is within design param-
 eters: dust loading at ESP inlet and outlet, gas velocity distribu-
 tion, electrical voltage and current input, gas composition, and
 dust resistivity (Oglesby and Nichols, 1970).

 6.2.5   Cost Estimating Procedure
  A cost analysis was performed by Vatavuk, 1990 for various
 ESP systems ranging from 10,000 -1,000,000 ft2 in size. A cost
 correlation forESPs based on plate area based on this analysis is
 presented in Figure 6-8. The cost of material can have a signifi-
 cant affect on the cost of the ESP. The cost factors for upgrading
 from carbon steel to another more specialized material are shown
 in Table 6-6. The costs for two-stage ESPs arepresented in Figure
 6-9. This figure contains costs for the  basic system and for
 packaged systems.             ,           	          ,

  The total capital  investment is determined from direct and
 indirect costs.  The capital cost factors for ESPs are presented in
 Table 6-7. Since a packaged two-stage system includes some
 installation costs, the total direct costs for installation for two-
 stage ESPs is  approximately 0.20B to 0.30B (Vatavuk,  1990).
The annual operating cost estimates forESPs are given in Table
6-8. Vatavuk,  1990 contains further detailed cost analysis infor-
mation for ESPs.
                  10000
                   200
                                                                     100
                                                  Collection Plate Area, Ap (1000 ft2)
                                                                                    1000
Figure 6-8. ESP equipment cost
                                                         86

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Table 6-6.  Cost Factors for Upgrading ESP Construction Material

     Material                                   Factor
Stainless Steel, 316
Carpenter 20 CB-3
Monel-400
Nickel-200
Titanium
1.3
1.9
2.3
3.2
4.5
Source: U.S. EPA, 1990.
6.3     Operational Controls
  Operational controls are those procedures or practices inherent
to the operation (and design) of control systems that can be
followed to minimize the overall long-term emissions. Among
these are:

  • Adequate system design and installation;
  • Startup testing;
  • Preparation of standard operating procedures for
    operators;
  • Control of operating variables to minimize emissions;
  • Monitoring of system performance;
  • Minimization of process upsets and startups; and
  • Preventative and routine maintenance.

  Operational controls for particulate matter and acid gas con-
trols follow the same philosophy as those for VOC controls (see
Section 5.7).

6.4     Wet Scrubbers
6.4.1   Process Description
  Wet scrubbing is one of the most widely used methods of flue
gas treatment for the control of acid gases, particulate matter
(PM), heavy metals, and trace organics. The use of two or three
different types  of scrubbers in sequence  can result in high
removal efficiencies, particularly for acid gases. The absorption
may be either physical or chemical. Physical absorption occurs if
the pollutant is merely trapped by the liquid, e.g. particulate
matter impingement on water. Chemical absorption occurs when
a reaction takes place between the pollutant and the liquid; e.g.,
HC1 reacting with a lime-based slurry to form CaCl2. Note: dry
scrubbing, the injection of an alkaline reagent into the gas stream
                 120
                 100
              *   60
              8
              CD
                  40
                  20
                                       Packaged Systems
                                                        I
                                                             System without Precooler,
                                                             Installed Cell Washer, or Fan
                                                                   I
                                                       6           8
                                                     How Rate (1000 scfm)
                                                                              10
                                                                                          12
                                                                                                     14
       Figure 6-9. Purchase costs for two-stage precipitators.
                                                          87

-------
 Tablo 6-7.  Capita) Cost Factors for ESPs
              Cost item
                                                                                                              Factor
 Direct Costs
     Purchased equipment costs
         ESP + auxiliary equipment
         Instrumentation
         Sales taxes
         Freight
             Purchased equipment cost, PEC

     Direct installation costs
         Foundations and supports
         Handling and erection
         Electrical
         Piping
         Insulation for ductwork
         Painting
             Direct installation costs
    Site preparation

    Buildings
                         Total Direct Costs, DC °
Indirect Costs (installation)
        Engineering
        Construction and field expenses
        Contractor fees
        Start-up
        Performance test
        Model study
        Contingencies
                         Total Indirect Costs, 1C

Total Capital Investment - DC + 1C
  For two-ataga pfeclpitators, total Installation direct costs are more nearly 0.20 to 0.30 B + SP + Bldg.
                                                                                                            As estimated, A
                                                                                                                   0.10 A
                                                                                                                   0.03 A
                                                                                                                   0.05 A
                                                                                                                B=1.18A
                                                                                                                   0.04 B
                                                                                                                   0.50 B
                                                                                                                   0.08 B
                                                                                                                   0.01 B
                                                                                                                   0.02 B
                                                                                                                   0.02 B
                                                                                                                   0.67 B

                                                                                                           As required, SP

                                                                                                          As required, Bldg.
                                                                                                        1.67B + SP + Bldg.
                                                                                                                   0.20 B
                                                                                                                   0.20 B
                                                                                                                   0.10 B
                                                                                                                   0.01 B
                                                                                                                   0.01 B
                                                                                                                   0.02 B
                                                                                                                   0.03 B
                                                                                                                   0.57 B

                                                                                                       2.24 B + SP + Bldg.
 SOIKCO; Valavuk, 1890.

 while not allowing the gas to be saturated with water vapor, is
 discussed in Section 6.5.

   The physical concepts involved in wet scrubbing are quite
 simple: use of a liquid to absorb pollutants from a waste gas
 stream, enhanced through a large liquid/gas contact surface area.
 Gaseous matter is removed by diffusion and absorption of the
 pollutant into the  liquid. Quenchers work by condensing the
 gases into a liquid. The absorber removal rate is a function of the
 concentration of the vapor, and the equilibrium concentration of
 the I iquid phase of the pollutant with the scrubber liquid. Particu-
 late scrubbers (Venturis) capture particles by impingement and
 agglomeration with the liquid droplets.

   The use of a scrubber, which introduces a liquid into the waste
 gas stream, requires a liquid separator downstream of the ab-
 sorber. Separators can be cyclones, mist eliminators, or swirl
 vanes, and use impaction or centrifugal force to remove the liquid
 droplets from the exhaust stream. Mist eliminators can be either
 the chevron or mesh pad type.

  The pH of the scrubbing liquor is an important process vari-
 able. Although even an acidic liquor can remove some HC1, HF,
 PM, and metals,  a more neutral liquor is required for high
removals of other pollutants. A pH of 5.0 or higher is required for
SO2 removal. Trace organics removal also is enhanced  by an
                                                              alkaline pH. The most common alkaline scrubbing reagents are
                                                              lime, limestone, sodium hydroxide, and sodium carbonate.

                                                                Sodium-based scrubbing liquors have the advantage over
                                                              calcium reagents of being less prone to causing scale formation
                                                              on scrubber internal surfaces. Gypsum scale, which is formed in
                                                              calcium-based processes, can be particularly difficult to remove.
                                                              However, gypsum scale formation can be avoided through proper
                                                              design and operation. Sodium reagents also have the advantage
                                                              that they can provide higher removal rates, but usually they are
                                                              more expensive than lime or limestone. Calcium-based scrubber
                                                              waste products, however, are typically easier to dispose than
                                                              sodium-based solids. The higher solubility of sodium salts makes
                                                              leaching more of a problem from such waste streams. Therefore,
                                                              the planned disposition of scrubber byproduct solids will be a
                                                              factor in the selection of a reagent.

                                                                Wet scrubbing can be accomplished by many methods. Four
                                                              such processes are illustrated in Figure 6-10. A discussion of
                                                              these four and others is found below.

                                                                High Efficiency Venturi Scrubber-Venturi scrubbers often
                                                              are used as a primary control device, operating at a low pH to
                                                              remove particulates and hydrogen chloride. The particulate re-
                                                              moval efficiency in a venturi is normally in trie range of 80 to 95%
                                                              for particles larger than 0.2 microns (Brna, 1987).
                                                          88

-------
  This device uses the venturi principle to scrub the waste
stream: as gas enters the venturi throat, its velocity increases, and
scrubber liquor is introduced as a spray perpendicular to the gas
stream. The high gas velocity atomizes the liquid, creating a large
surface area for absorption. The small droplets agglomerate as
the gas velocity decreases downstream.

  Prefabricated units can handle waste streams of up to 80,000
cfm. Although these units are considerably less expensive  than
ESPs or fabric filters, the savings may be offset by their  high
pressure drop. Removal efficiency increases with increasing
particle size and increasing venturi pressure drop.

  Jet Venturi Scrubber-These systems use energy from pressur-
ized liquid to induce a draft which entrains the flue gas. The jet
scrubber is capable of PM collection efficiencies of 90% or
better, and will also remove  acid gases. The jet scrubber can
process gas directly from the combustion chamber, but  it is
usually preceded by a quencher.

  Packed Tower Scrubber-Packed towers are primarily used for
gas absorption. In this system, waste gas enters at the bottom of
the unit, and the  scrubber liquid is sprayed onto the top  of a
packed bed. As the gas passes upward, it contacts falling liquid
that absorbs the pollutant. A mist eliminator above the packing
removes liquid droplets from  the gas stream, and cleaned gas
exits the top. This type  of scrubber can typically achieve higher
removal  efficiency than other scrubber devices, due to its  high
liquid/gas contact surface area.
                   Spray Tower Scrubber-This system is also primarily used for
                 gas absorption. Three configurations can be used. The gas can
                 flow upward or  countercurrent to liquid spray; downward or
                 cocurrent to spray; or, horizontally through a vessel with spray
                 perpendicular to the gas flow direction. The main design vari-
                 ables affecting spray tower efficiencies are tower height, liquid
                 to gas ratio, gas velocity, droplet size, and liquid chemistry/pH.
                 The spray tower must operate with a higher liquid to gas flow
                 ratio than the packed tower, to achieve equivalent removal rates.

                   Tray Scrubber—These units typically are in the form of a
                 vertical cylindrical tower with many levels of trays inside. The
                 scrubber liquor is recirculated through the absorber, with a layer
                 of liquor being held on each tray. The flue gas bubbles up through
                 holes in each tray, ensuring a high surface contact area. These
                 systems can be bubble-cap, perforated-tray, or valve-tray scrub-
                 bers. Often, one or more trays can be added to enhance the mass
                 transfer performance of open spray tower absorbers.

                   Quencher—This type of device typically is not used on its own,
                 but instead is used as the first step in a wet off-gas treatment
                 system. Quenchers are similar to spray tower scrubbers, but they
                 are used for pre-treatment and they are designed for temperature
                 control and humidification rather than pollutant removal. A
                 quencher can cool the off-gas from incineration temperatures to
                 saturation or near saturation temperature, increase the humidity
                 to or near saturation, and reduce gas volume. The degree of
                 approach to saturation temperature depends mainly on the liquid
                 rate, droplet surface area, and gas residence time. This increased
Table 6-8. Annual Operating Maintenance Costs for ESP System
        Cost item
                                                                                            Calculation
Direct Annual Costs, DC
    Operating labor
        Operator
        Supervisor
        Coordinator

Operating Materials
    Maintenance
        Labor
        Material
    Utilities
        Electricity-fan
        Electricity-operating
        Waste disposal
Total DC
Indirect Annual Costs, 1C
  Overhead

  Administrative charges
  Property Tax
  Insurance
Total 1C
Total Annual Cost (rounded)
            3 hr/day x 6 (day/yr) x hourly rate
            15% of operator
            1/3 of operator
             0.0825A (minimum of $5,265)
             1% of purchased equipment cost

             0.000181 x Q x AP x 9 x electricity cost ($/kwh)
             1.94x10-3xAx0x electricity cost
             DD=4.29x10-6xGx9  xQx [T+ (TM x D)]
            60% of sum of operating, supv., coord., and maint. labor and maintenance
            materials
            2% of TCI
            1% of TCI
            1% of TCI

            DC + 1C
where:   8    = Operating time (hr/yr);
        A    - ESP plate area (ft2)
        Q    = Flow rate (acfm);
        AP   m System pressure drop (in H2O);

Source: Adapted from Vatavuk, 1990.
G   = ESP inlet grain loading (gr/ft3);
T   - Tipping fee ($/ton);
TM  = Mileage rate ($/ton mile); and
D   = Hauling distance (mile).
                                                           89

-------
  Dirty
gas in
                              Clean gas
                                 out

                                                      solvent
                                                      in
                           o  o   o    o
                                    °
Bubble caps or
perforated
trays
                                              Slurry
                                              out
                                                                       Clean gas
                                                                          put

                                                             Mist
                                                        eliminator
                                                                                    Packing
                                                   DirtV
                                                  gas in

                                                                                             '••*••*••*••'••'•***•*••'•'
                                                                                                     0  0

                                                                                                     0 .    0
                                                                                         Clear liquid
                                                                                         wash
                                                                                                                    Scrubbing
                                                                                                                    liquid in
                                                                                        Slurry
                                                                                        out
                           a. Tray Scrubber
                                                                     b. Packed Tower
                  Dirty,
                gas in

                  Scrubbing
                  liquid
                  recycle
   &. f»J


      <;'
/
                               Tank
                                                 Clean
                                                  gas
                                                  out
                                                                              Hot gas
                                                                                from
                                                                           incinerator
                                                                                    Quench
                                                                                      tower
                                                                                                                    Water
                                                                                                                    recycle
                                                                                                                        Quenched
                                                                                                                        gas to
                                                                                                                        scrubber
                        c. Venturl Scrubber
                                                                                              d. Quencher (spray tower)
Figure 6-10. Four common types of wet scrubbing systems.
                                                               90

-------
humidity inhibits evaporation and contributes to absorption
efficiency in downstream devices.

  Quenchers are capable of some scrubbing, and can remove up
to 50% of the acid gas present in a waste stream, (if the scrubber
liquor contains an alkaline reagent). The quencher can be fol-
lowed by a higher efficiency scrubber unit, such as a venturi or
packed tower.                •

6.4.2   Applicability to Remediation Technologies
  Incineration commonly generates the pollutants that wet scrub-
bers remove most cost-effectively: acid gases, heavy metals, and
particulate matter. Wet scrubbing is also  applicable to other
thermal treatment methods  such as thermal desorption. The
particulate removal efficiency of a wet scrubber usually is not as
high as that of a baghouse or ESP. One possible drawback to the
use of wet scrubbers is that the flue gas temperature is cooled to
its saturation temperature. This will lower the dispersion charac-
teristics of the released flue gas and can result in a visible plume.
Hue gas reheating may be required to eliminate the plume.

  Some attributes of wet scrubbers that make them a popular
choice among pollution  control  devices is their simplicity of
operation, as compared with some other control devices. How-
ever, there are drawbacks: for VOC control, solutions other than
water are usually required,  since most VOCs are not water-
soluble. Therefore, proprietary  solvents are required,  which
raises the cost. Also, these devices are not efficient for low VOC
concentrations,  and must be used in conjunction with other
controls for these applications.

  Wet scrubbers achieve high efficiencies for  the removal of
heavy metals, since most of the volatile metals (except mercury)
will condense at the temperatures reached in  wet scrubbers.
Mercury has a higher vapor pressure than the other heavy metals,
and will not condense a"s readily. The collection efficiency of
mercury vapors in wet scrubbers  is not well known.

  Physical scrubbing does not destroy pollutants, it only trans-
fers them from the gaseous medium to a  solid or liquid medium.
Chemical absorption may well neutralize but will not destroy the
pollutant, as when acid gases are chemically absorbed by an
alkaline solution and form salts. Therefore, some waste usually
is generated, which must be treated or disposed. This additional
cost will affect the economics of the wet scrubber option.

  Because of the relatively specialized nature of wet scrubbers,
there is not one standard configuration used for all jobs; rather,
the scrubber sy stem(s) chosen will depend on the pollutants to be
removed and on the physical characteristics of the waste stream.
Typical wet scrubbing systems used with thermal treatment of
hazardous materials and wastes are described below.

  Thermal Desorption—One combination of wet scrubbers used
for this application is a quench chamber followed by a venturi
scrubber. This system would primarily be used to control particu-
late emissions, but could also control acid gases if the hazardous
waste feed contains halogenated compounds.
  Incineration—Wet scrubbers typically are used for cases not
requiring very high total and  fine (<10 micron)  particulate
removal or when inlet loading is not too high. All types of
scrubbers may be used, depending on the waste stream param-
eters. Sometimes, wet scrubbers are the only controls used for
removal of pollutants. Their ability to remove heavy metals, trace
organics, and acid gases makes them especially well-suited to
incinerator control.

  One typical combination would be a quencher for cooling and
condensing the hot waste gas as well as initial acid gas collection,
followed by a venturi for primary particulate removal, and then
a packed or spray tower for final acid gas absorption.

  A wet scrubber also may be used downstream of an ESP or
fabric filter, in situations that require higher PM removal than a
venturi alone can achieve, to control acid gases, and to control
some fraction of the heavy metals and trace organics that make
it through any prior APCDs.

6.4.3   Range of Effectiveness
  Absorption efficiency depends on many factors, including
viscosity, diffusivity, density, temperature, liquid surface area,
system chemistry, and flow rates. Absorption efficiency is en-
hanced by increasing liquid-gas interface surface area, reducing
temperature, and maintaining a high liquid-gas ratio. Wet scrub-
bing does not remove pollutants efficiently from low volumetric
flows; however, increased turbulence enhances removal rates.
Typical liquids used to date include water, non-volatile organics,
and alkaline solutions. The latter  is especially common as the
liquid in a second scrubber, since absorption of acid gases is
enhanced if the pH of the solution is maintained in the range 6.5
to 9.0.

  The use of common  types of wet scrubbers for PM control is
limited by the particle size distribution and the removal require-
ments. The wet scrubber systems described above may reach a
maximum of about 99.5%  removal.  Newer hybrid types of
scrubbers are being developed that combine wet scrubbing with
other processes, such as ionization, increasing the equipment's
range of effectiveness and improving its economics.

  Wet  scrubbers are often the  technology of choice for high
removal rates of acid gases. HC1 removal efficiency will usually
be greater than 99%. SO2 is more difficult to remove than HC1,
but removal rates greater than 95% can be achieved.

6.4.4   Sizing Criteria
  Sizing wet scrubbers for remediation applications is a difficult
process, requiring the determination of many design variables,
including flue gas saturation temperature,.tower heights, packing
requirements, etc. The interested reader is referred to U.S. EPA,
1991 or Vatavuk, 1990, which asserts "...in reality, column
design is so complex that nearly all towers are custom fabricated,
making itextremely difficultto postulate a general costing/sizing
procedure."

  Some of the costing equations  given in the next subsection
require an estimate of the diameter of the scrubber unit. The
                                                         91

-------
diameter (ft.) can be calculated from the flow rate Q (cfm) and
velocity V (ft/min) using the following equation:
                                                (Eq.6-4)
  A typical design velocity for non-venturi scrubbers is 10 ft/sec.
In a wet scrubber, the gas will be saturated with water vapor, and
the gas volumetric flow rate, Q, must be based on this saturation
temperature. Thescrubber process should be optimized by choos-
ing the best diameter and gas velocity.

6.43   Cost Estimating Procedure
  Capital Coste—Equipment costs will vary with the system. A
representation of some equipment costs are presented below.

  A venturi system consisting of a mist eliminator, recirculation
liquid pump, and sump in addition to the venturi, all in carbon
steel, would cost (Vatavuk, 1990):

P-S9018 +1.55 Q for 600 <: Q < 19,000 acfm       (Eq. 6-5)
P-S92.8 Q0612 for 19,000 < Q < 59,000 acfm        (Eq. 6-6)

  For applications with corrosive streams,  carbon steel is not
appropriate. To obtain the cost of this venturi system with a
rubber lining, or fabricated of fiber-reinforced plastic, multiply
the above equations by 1.6. For epoxy coated carbon steel,
multiply by 1.1.  Instruments and controls cost approximately
10% of the equipment cost.

  A costing equation was developed (Vatavuk, 1990) for im-
pingement scrubbers of 304 stainless with 1, 2, or 3 stages
(levels), internal sprays and piping. This  estimate does not
include fan.pumps, orother auxiliary equipment. In the presence
of chlorides, type 304 stainless is not appropriate and higher
grade alloys or linings are required. The following equation is
valid for parameters listed in the table below:
P - $ a Qb with 900 < Q < 77,000 acfm
                               (Eq.6-7)
  ThefollowingtwocostingguidelinesareadaptedfromHesketh,
1991:
   Stages
Effective height, ft.
1
2
3
8
16
24
58.9
68.8
69.5
0.570
0.586
0.610
    Purchase cost of packed tower absorbers, Pa, in 1992
    dollars can be estimated by:
                Pa-1337 D0-75
                               (Eq.6-8)
  where:
        D   -  Column diameter, in inches, from 10 to 200.

    Packing cost per cubic foot of material Pp is:
                                                            Pp =
                      32.2

                     (Sp1-05)
(Eq. 6-9)
                                                              where:
                                                   Sp  =   Packing size from 1 to 3 in.

                                             Hesketh's estimate for mist eliminators is $121/ft2 of cross-
                                           sectional area. Vatavuk, 1990, estimates mist eliminator cost for
                                           mesh pad designs by:
                                                                 86.4 D1-66
                                              (Eq. 6-10)
where, again, D is the diameter of the unit and typically is
between 2 to 10 feet.

  Installed capital costs are 2.2 times equipment cosii. Installed
absorber costs are in the range of $9.1 -18/scfm for systems with
a flow greater than 10,000 scfm (Hesketh, 1991).

  Operation and Maintenance Costs-A. conservative estimate
(Vatavuk, 1990) is that operation  and maintenance must be
performed 1/8 of the annual running time. Corrosion and scaling
are the main sources of maintenance. Mist eliminators will need
periodic replacement. The major operation costs are for chemical
reagent, makeup water,  and operating labor. Additional cost
considerations include:

  • Absorbers usually operate automatically, needing little
    labor or maintenance;
  • Where Venturis are used, most power is to regain pressure
    after scrubbing;

  • Unlike fume destruction, absorbers incur fees for disposal
    of waste solids; and

  • The wastewater may be disposable in an existing-on-site
    treatment system or used to cool heated soil.

6.5     Dry Scrubbers
6.5.1   Process Description
  There are two principal types of dry absorption systems: dry-
dry and semi-dry absorption. Dry-dry systems inject the alkali
absorbent as a dry powder, and semi-dry systems inject the alkali
in a concentrated slurry, then evaporate the liquid. Both types of
systems remove any unreacted alkali and solid wastes via ESP?
or fabric filters. A dry scrubbing device includes a chemical
injection zone, a reaction zone where the pollutants react with the
alkali, and  a particle removal  device where the solids are re-
moved from the waste  stream. Figure  6-11 illustrates three
commonly used dry scrubbing systems.

  The most common use of this technology with remediation
systems is for incinerators. Wherever halogenated compounds
are thermally destroyed, some type of scrubber (wet or dry) will
usually be required to remove the resulting acid gas. Dry scrub-
bers operate on absorption principles similar to wet scrubbers,
but produce lower pressure drops and require less power. An-
other difference is that  the waste  gas is  not saturated  with
                                                        92

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               Flue gas in
                       Quench
                         tower
                      (optional)
I                                          Water
                                          (optional)
Figure 6-11 a. Dry sorbent injection process.
              Hydrated
              lime silo
                                                                           -Air
                                                                     Blower
                                             Dust
                                            collector
                                                                                                                        Stack
                                                                                                                   Fan
                                                                                                                   Dry waste
                          Hydrated
                          lime silo
              Air.
                   Blower
                                                              Precollector
Circulating
fluid bed
reactor
                                                           Recycle
                                                     Water
                                                           Flue gas in
                                                                                         Dust
                                                                                        collector
                                                                             Periodic
                                                                             recycle
                                                                                                                      Stack
                                                                                                               Dry waste
Figure 6-11b. Circulating fluid bed reactor process.
                                              Pump
                                                                            Particle recycle
                                                                               (optional)
                                                                                                                      Dry waste
Figure 6-11c.  Spray dryer absorption (semi-dry) process.
                                                                         93

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 moisture, and the waste material is collected in dry form. With
 wet scrubbing the plume must usually be reheated, and waste is
 typically aslurry. A wet waste can be a liability, if alarger volume
 of waste is generated for disposal. These advantages  of dry
 scrubbers are sometimes offset by their need  for a separate
 downstream paniculate collection device. High  sulfur removal
 rates (>90%) are  generally more difficult and expensive to
 achieveinadryscrubberthaninawetscrubber.Thestoichiomet-
 ric ratio (i.e. moles of absorbent per mole of pollutant absorbed)
 is higher with dry scrubbers than with wet scrubbers.

   Practically all dry chemical absorbers use alkalis, in particular
 calcium and sodium, which have good absorbent properties for
 many of the acid gases and for some organic pollutants. In dry
 scrubbers the calcium-based absorbent is usually in the form of
 slaked lime, Ca(OH)2. The solids, including both used and
 unused absorbentparticles, and particulate matter from the waste
 stream, are collected at the bottom of the absorber vessel, and in
 a baghousc or other particulate separator. Removal efficiency is
 mainly dependent on the acid-alkali ratio and  the outlet gas
 temperature. Fabric  filters and ESPs are the most  common
 removal devices downstream of dry scrubbers. Acid gas removal
 efficiency is enhanced as the gas passes  through the particle
 separator. However, a fabric filter provides greater removal of
 acid gases than does an ESP. The collected solids often can be
 recycled, to achieve greater utilization.

   The use  of dry scrubbers for  power plant applications is
 relatively common, and standard design and operating param-
 eters have been  developed. The use of dry scrubbers for hazard-
 ous waste incinerators and remediation projects, however, is less
 well-defined. There are many control possibilities, and no single
 combination of scrubbers, fabric filters, ESPs, etc. is best for
 every application. Some typical systems are described below.

  Dry-Dry Systems—Dry sorbentinjection (DSI) involves inject-
 ing hydrated lime or limestone directly into the furnace or into the
 ductwork downstream of the furnace (see Figure 6-1 la). Sulfur
 dioxide removal efficiencies of about50% have beenreported for
 this technology. The process has a high alkali requirement, and
 erosion of mechanical components can be aproblem. Dry sorbent
 injection uses pneumatic equipment to introduce alkali into the
 hot gas stream. The gas stream may be humidified between the
 furnace and the particulate control equipment to improve re-
 moval efficiency. In general, SO2 removal efficiencies increase
 with more alkali, greater contact time, higher pollutant concen-
 tration, higher moisture content, and lower temperature at the
 particulate control device inlet (to about 20-30°F above satura-
 tion temperature). On the other hand, if the gas stream is not
 humidified, higher temperatures may make separation of other
pollutants difficult, and also may allow formation of polychlori-
 natcddibcnzodioxins(PODDs),polychlorinateddibenzodifurans
 (PCDFs), and other products of incomplete combustion (PICs).
Dry-dry systems therefore are not used as the only device for
control of hazardous air pollutants (HAPs).

  Semi-Dry Systems—This process consists of conditioning the
gas to a temperature above its saturation point by the adiabatic
evaporation of water. An alkali is injected into the gas  either as
a slurry with the  water, or separately. As with wet scrubbing, this
causes cooling and a decrease in gas volume, as well as chemical
reaction with the acid gases. A fabric filter or ESP then collects
the particles and also may serve as a secondary reaction bed.
Semi-dry systems have the advantage of no liquid waste, but by
cooling the waste gas avoid the dry-dry problems with PICs
discussed above. Further, the presence of liquid droplets in the
semi-dry process produces higher acid gas removal rates than do
dry-dry systems.

  In spray dryer absorber (SDA) systems, hydrated lime is the
most common alkali sorbent, and is mixed with water to form a
slurry of approximately 15% Ca(OH)2. The dosage of lime is
regulated according to the acid gas concentration in the flue gas
and.the desired removal rate. This process often is used for power
plants and municipal solid waste (MSW) incinerators, and as
such has been well studied. The slurry can be introduced to the
SDA by single or multiple rotary atomizers, or multiple dual fluid
nozzles. Slurry droplet size is about 50 to 90 urn. With respect to
gas flow, the SDA vessel .can be downflow, upflow, or upflow
with a cyclone pre-collector, and can have single- or multiple-gas
inlets. Acid gas removal can be as high as 95% for SO2,994-% for
HC1, 99+% for SO3, and 95% for  HF. The temperature of
incoming gas can be up to 1000°C since the evaporating liquid
will cool it back to 100 to 180°C. Flue gas residence time is J 0 to
18 seconds, and up to 25% of the reaction products and ash can
be collected in the SDA vessel.

6.5.2   Applicability to Remediation Technologies
  Dry absorption has two features that make it relatively less
attractive as a control  for remediation purposes.  First, it  is
difficult to achieve the very high removal efficiencies of wet
scrubbers or other technologies. Second, dry absorption adds to
the volume of waste to be disposed of because of the absorbent
in the slurry. On the other hand, dry absorption has some aspects
whicrrare useful for some remediation applications;  it is able to
handle heavy  metals, PM,  and acid gases, as well as trace
organics and some PICs. PCDD and PCDF removal rates for
SDA/baghouse systems can reach 90 to 99+% (Donnelly, 1991).
Dry activated carbon can be added to the SDA to increase the
removal of heavy metals and trace organics. SDA systems also
show promise for mercury removal. The applications where dry
absorption is used are described below.

  Incinerators—Dry absorption is effective for every type of
pollutant in the incinerator exhaust gas streams,  to varying
degrees; sticky or corrosive particles are not a problem. Spray
dryer absorption often is used, with a spray dryer coupled with a
fabric filter. Reagent addition, flue gas humidification, and most
of the absorption take place in the dryer; additional  absorption
occurs in the collector as dust is removed from the gas stream.
The acid gases, trace metals, and trace organic compounds
present in the waste stream of an incinerator are the pollutant
types that SDAs control best. High electrical power costs can
result from maintaining air pressure to dual fluid nozzles. Rotary
atomizers consume less electrical power than dual fluid nozzles.
Reagent and disposal costs are generally higher than for wet
absorbers; however, the dry system itself has a lower capital
investment cost.

  The end product from an SDA is hygroscopic with a significant
soluble fraction, stickier than fly ash and more difficult to handle.
                                                        94

-------
End.product constituents include fly ash, calcium compounds,
trace metals, and trace organics. Due to its origin, this material
must be disposed of as hazardous waste. If the fabric filter would
be clogged by lime residue or unable to withstand  the high
temperatures, another post-SDA control, such as an ESP, can be
used.                    ,            .

  Thermal Desorption—Systems used as controls for thermal
desorbers typically include an SDA for acid gases with a bag-
house filter forparticulate matter. This combination can meetthe
desired removal rates for acid gases, heavy metals, and trace
organics.

6.53   Range of Effectiveness
  Removal efficiencies for an SDA/baghouse system can range
as high as,99%+ for most incinerator pollutants: acid gases, and
heavy metals. More commonly, removal rates will be near 70 to
80%. Spray dryers with ESPs can remove 98% of dioxins and
furans  (PCDD/PCDF). The achievable removal efficiencies for
an SDA/baghouse operating on the waste stream from an incin-
erator are indicated in Table 6-9.           .         -...-,

  SDA systems can accommodate input temperatures up to
1000°C. -They are capable of handling a wide range of flue gas
flow rates, although they are not very effective at removing low
concentrations of pollutants.

6.5.4   Sizing Criteria
  The  major design variables for an SDA system are gas resi-
dence,  time and reagent slurry flow rate. Residence time is a
function of SDA volume, flue gas flow, and gas inlet and exit
temperatures. SDA volume determines the size of the vessel.
Reagent slurry flow rate determines the size of slaking, pumping,
and atomization equipment. The required slurry flow rate de-
pends  on  many factors including gas temperatures, concentra-
tions and types of pollutants, use of solids recycle, and type of
reagent.         .
  For both SDA and dry injection, the capital cost of a system of
one size may be approximated from the known cost of a system
of another size by the sizing exponent:

                n = 0.73                       (Eq.6-11)

This parameter is used in the sizing equation:

                Ib - la (Cb/Ca)n                (Eq.6-12)

where Ib is the cost of a system of size Cb, and la, Ca are the
respective cost and size of a reference system. An estimate of the
installed-cost-to-purchase ratio is 2.17 (Hesketh, 1991).


-------
 6.6     HEPA Filters
 6.6.1   Process Description
   High efficiency paniculate air (HEPA) filters are commonly
 used in medical, research, and manufacturing facilities requiring
 99.9% or greater paniculate removal. Although their use during
 remediation activities at Superfund sites has not been wide-
 spread, they could be used as a PM polishing step in ventilation
 systems for buildings undergoing asbestos removal, for enclo-
 sures, or with solidification/stabilization mixing bins.

   The major components of a PM control system employing
 HEPA filters include the following:

   •  HEPA filters;
   •  Filter housing;
   •  Duct work; and
   •  Fan.

 Such a system is shown in Figure 6-12.

   The HEPA filter housing unit required is dependent on the
 nature of the PM collected and on the number/arrangement of
 filters required. For example,, PM consisting pf asbestos or PM
 laden with dioxins/furans will require a bag-out housing unit be
installed. This type of housing unit is designed so that personnel
removing the HEPA filters are never in direct contact with the
filters. Such a unit is shown in Figure 6-13.

  HEPA filters can be arranged in parallel, in series, or in a
combination of these arrangements depending on the degree of
PM control desired and the allowable pressure drop across the
filters. Generally, parallel filter arrangement will lower the
pressure drop across the filters, but will increase the size of the
housing unit. Serial filter arrangement generally will increase the
PM collection efficiency and the total pressure drop.

6.6.2   Applicability to Remediation Technology
  The advantages/disadvantages of using HEPA filters to con-
trol PM emissions are  given in Table 6-10. Remediation tech-
nologies with which HEPA filters are compatible are listed in
Table 6-11.

6.6.3   Range of Effectiveness
  Parameters that will affect the efficiency and/or useful lifetime
of HEPA filters are outlined in Table 6-12. Vendors report HEPA
filter PM control efficiencies to be 99.9% and up for paniculate
diameters of 0.3 microns.
                      Airflow
                      Direction s
                                                                Hepa
                                                                Filters
                                                 Hepa   Adsorbers
                                                 Filters
                  Downstream
                    Plenum
                                 Prefilters
                                                                                          Airflow'
                                                                                          Direction
                                   Upstream
                                    Plenum
          Source: Flanders, 1984.

Figure 6-12. PM control system employing HEPA filters.
                                                        96

-------
                                                    Door hand
                                                    knowb stud
                                      Filter
                                    removal
                                        rod
                                                                           Shaft seal
           Hand
           knob
                                                                                                           Locking
                                                                                                          mechanism
                                                                                       s- Type FE
                                                                                          adsorber
                                                  Door
                                                                             «— Sample port
                                                      2" pre-filter
                                                         track        Filter-locking
                                                                   mechanistm shaft
               Source: Barneby-Cheney, 1987.
Figure 6-13. Bag-out HEPA filter housing unit.
Table 6-10.  Advantages/Disadvantages of HEPA Filters


                         ,  Advantages
     Disadvantages
              Easy to operate


              99.9% or greater PM removal efficiencies are achievable
May require prefilter for exhaust with high PM
concentrations

Required housing units are expensive and may be
subject to corrosion
Filters are subject to fouling by high humidity
exhaust gases
Filters must be replaced periodically due to
plugging caused by PM
High power costs due to pressure drop across
filter          	,'   ,	__
                                                                 97

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  Table 6-11.  Remediation Technologies Compatible with HEPA Filters


  	       Emission Source
                                                                                        Qualifications
           Asbestos removal from buildings
           Enclosure ventilation system
          Hoods or enclosures of solidification/stabilization mixing bins
                                   HEPA filters must either be installed in building
                                   ventilation system or negative air pressure system used
                                   during asbestos removal
                                   HEPA filters will require bag-out housing units and must
                                    be disposed of properly

                                   Pre-filters may be required for high PM concentrations
                                   Depending on the nature of the PM (e.g., heavy metal
                                   or SVOCs contamination), bag-out housing units may
                                   be required
                                   High humidity within the enclosure will limit filter lifetime

                                   HEPA housing material may be subject to corrosion
                                   due to lime
                                   Pre-filters may be required for high PM concentrations
                                   Depending on the nature of the PM  (e.g., heavy metals
                                   or SVOCs) bag-out housing units may be required
                                   High humidity exhaust gases will limit filter lifetime
  Table &-12.   Parameters Affecting HEPA Filter Efficiency/Lifetime
              Parameter
                                                                             Comments
               Moisture


             PM loading
Moisture will bind filter resulting in increased pressure drop across filter, eventually leading to
filter failure due to excessive resistance.

Higher the PM loading the shorter the useful life of the filters. Also, the change in pressure drop
across the filters will be accelerated.

Higher the velocity, the lower the PM control efficiency, higher the pressure drop across the
filter, and diminished filter life.
6.6.4   Sizing Criteria/Application Rates
  Sizing of HEPA filters is based on pressure drop vs. face
velocity curves which are developed by the manufacturer for
each type of filter design. If the maximum allowable pressure
drop across the filter and the air flow rate are specified, then the
type of filter and the filter arrangement can be determined. A
family of pressure drop vs facet velocity curves is depicted in
Figure 6-14.

  If, for example, HEPA filters are to be used to control PM
emissions in an exhaust gas flowing at 9000 acfm (2250 fpm for
a 2 ft x 2 ft HEPA filter) and the maximum allowable pressure
drop across the filter is 0.8 inches H2O gauge, then ten-H2424B,
nine-H2430B, eSghteen-H2424A HEPA filters must be used in
parallel (see Figure 6-14).
                     6.6.5   Cost Estimating Procedure
                       HEPA filter costs are dependent on the specific filter charac-
                     teristics:

                       • PM removal efficiency achievable; and
                       • Maximum face velocity allowable across filter.

                       Also, the useful filter lifetime is dependent on face  velocity
                     across the filter, PM loading rate, and the moisture loading rate
                     onto the filter. The useful lifetime will determine the frequency
                     of filter replacement. Generally the range of HEPA filter costs is
                     $20 - 100/ft2 filter area. The costs.of housing units is a function
                     of the type of housing unit required (e.g. regular vs. bag-out) and
                     ranges in price from $ 150-500/ft2 filter area.
                                                             98

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            1.8
            1.6
            1.4
        q

        I „
            1.0
         co
         s
            0.8
            0.6
             0.4
                                  H2424A
                               I
                                                               I	I	i
                                                                          I
                                                                                        I
                 0              4
            Face Velocity (1pm)     125
8             12             16
      250                 375

          Capacity x 100
20
500
24 (cfm)
        Source: HEFCO, 1989.                        '

 Figure 6-14. Pressure drop vs. face velocity curves for specific HEP A filter designs.
6.7     References
  Barneby and Cheney. Product Brochure. Barneby-Cheney,
      Columbus, OH. 1987.

  Brna, T.G. and C.B. Sedman. Waste Incineration and Emission
      Control Technologies. EPA/600/D-87/147 (NTIS PB87-
      191623). RTF, NC. May 1987.

  Brna, T.G. Controlling PCDD/PCDF Emissions from Incin-
      erators by Flue Gas Cleaning. EPA/600/D-90/239. U.S.
      EPA, Research Triangle Park, NC. September 1990.

  Brunner, C.R. Incineration Systems: Selection and Design.
      Van Nostrand Reinhold, New York, NY. 1984.

  Danielson,J.A.,ed. Air Pollution Engineering Manual Second
      Edition (AP-40). U.S. EPA, RTF, NC. May 1973.

  Donnelly, J.R. Air Pollution Controls for Hazardous Waste
      Incinerators. Thermal Treatment and Air Pollution Con-
      trol In: Proc. of the 12th National Conference on Hazard-
      ous Materials Control/Superfund '91. HMCRI, Silver
      Spring, Maryland. December 1991.
               Flanders. Product Brochure. Flanders Equipment, Washing-
                   ton, DC. 1984.

               HEFCO. Product Brochure. HEFCO, Eatontown, NJ. 1989.

               Hesketh, H.E. Air Pollution Control: Traditional and Hazard-
                   ous Pollutants. TechnomicPublishing Co., Lancaster, PA.
                   1991.

               HMCRI. Incineration Monograph. Hazardous Materials Con-
                   trol Research Institute, Silver Spring, Maryland. 1991.

               Lawless, P.A. and L.E. Sparks. A Review of Mathematical
                   Models for ESPs and Comparison of their Successes.'
                   Proceedings of the Secondlnternational Conf. onElectro-
                   static Precipitation, pp513-522. S. Masuda, ed., Kyoto.
                   1984.

               Oglesby, S. and G.B. Nichols. A Manual of Electrostatic
                   Precipitator Technology. Prepared by the Southern Re-
                   search Institute for the National Air Pollution Control
                   Admin. APTD-0610 (NTIS PB-196380). 1970.
                                                       99

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U.S.EPA(W.M.Vatavuk).OAQPSControlCostManual(4th
    Edition) EPA/450/3-90/006 (OTIS PB90-169954). RTP,
    NC. January 1990.

U.S. EPA. Handbook: Control Technologies for Hazardous
    Air Pollutants EPA/625/6-91/014. Cincinnati, OH. June
    1991.

Vatavuk, W.M. Estimating Costs of Air Pollution Control.
    Lewis Publishers Chelsea, MI. 1990.
                                                100

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                                                 Chapter 7
                  Area Source Controls for VOCs, SVOCs, PM, and Metals
  Information about various control technologies used to control
emissions from area sources is presented in this chapter. The
control technologies generally are applicable to the control of all
classes of air contaminants, including volatile organic com-
pounds (VOCs), semi-volatile  organic compounds (SVOCs),
particulate matter (PM), and metals associated with PM. The
specific control technologies addressed in this section are covers
and physical barriers, foams, wind barriers, water sprays, water
sprays with additives, operational controls, enclosures, collec-
tion hoods, and miscellaneous controls. The discussion for each
control technology includes a process description, applicability
for remediation technologies, range of effectiveness, sizing cri-
teria, and cost information.

  Emissions from area sources are more difficult  to measure,
model, and  control than emissions from  point sources. The
sources may be several acres in size and the concentration of
emissions in the source/atmospheric boundary layer is generally
very low. Therefore, the types of controls suitable for point
sources are not  applicable to area sources. Two general control
approaches exist for area sources: 1) Collect the emissions in a
hood or  enclosure and route the air stream to a point source
control device; and 2) Prevent the emissions from occurring. The
first approach is merely a conversion of the area source to a point
source and is the most suitable for batch or in-situ  remediation
processes such  as solidification/stabilization and  bioremedia-
tion. The second approach is  primarily suited for materials
handling operations such as excavation.

  Relative to point source controls, the capture efficiency and
control efficiency of area source controls tends to be low. Overall
control efficiencies may be only 50% or lower. Also, many of the
area source controls have short-lived effects and require frequent
reapplication. The controls are generally simpler in design than
point source controls  and do not require  as highly a trained
operator for their operation and maintenance. Finally, opera-
tional controls may be the single most cost-effective method of
minimizing emissions from area sources; their consideration is
strongly recommended.

7.1     Covers and Physical Barriers
  Cover materials used to control VOC and/or particulate matter
(PM) emissions include the following: soils, organic solids such
as mulch, asphalt/concrete (paving), gravel/slag with road car-
pet, and  synthetic covers (e.g. tarps). Cover materials are used
extensively at controlled landfills and construction sites for
vapor and dust suppression. The mostcommonuses of covers for
Superfund sites are soil covers for inactive sites; asphalt, con-
crete, or gravel covers for roadways; and thin polymer liners
(e.g., 45 mil HDP) for storage piles of contaminated soil.

  Soil material can range from top-soil to clays. However, sand
generally is not used because of its porous nature and tendency
to erode.

  Organic solids include such materials as wood chips, sawdust,
sludges, mulch, straw, corn stalks, etc. Because some of these
materials are prone to wind erosion (e.g., straw, cornstalks), they
must be anchored with a net. The availability of these materials
may limit their use.

  Synthetic liners (polymer sheeting) are relatively new and are
used widely at landfills to minimize leachate migration. They
also serve as a barrier to vapor transport. Liner thickness varies
from 2-125 mil; however, 30-60 mil is common. Some common
geomembranes are

  •  Polyethylene
     - High density—HOPE
     - Low density—LDPE - should not be used
     - Very low density—VLDPE
     - Linear low density—LLDPE
  •  Poly vinyl chloride (PVC)
  •  Chlorosulfonated polyethylene (CSPE)
  •  Ethylene interpolymer alloy (EIA)
     Note: Others will not sell to our industry due to potential liability.

  Road carpets are water permeable polyester fabrics that are
placed between the road bed and the coarse aggregate road ballast
(e.g., gravel, slag).

  The effectiveness of cover materials to  control VOC and PM
emissions is outlined in Table 7-1.

7.1.1    Process Description
  Covers control emissions of contaminated particulate matter
and VOCs by physically isolating the contaminated media from
the  atmosphere. Physical isolation  is the  primary means of
controlling particulate matter emissions, while increasing the
resistance to diffusion is the primary means of controlling VOC
                                                         101

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Table 7-1.  Cover Material Effectiveness for Controlling VOC and
           Paniculate Emissions
Contaminated
Cover material media
Soil
Organic solids
Goomembranes
Asphalt/concrete
Road carpet and gravel/slag
Soil
Soil
Soil
Sludge
Liquid
Soil
Soil
Control
effectiveness
VOCs
Low '
Low1
High1
High1
High1
None2
None2
Particulates
High
High
High
N/A
N/A
High
High
1  VOC emission control dependent on dilfusivity coefficient of individual VOCs
  through cover material and on cover material depth.
*  Assumes cover material is applied to unpaved roads only.
emissions. Mass emission rates for VOCs, assuming diffusion
only, can be determined from Equation 7-1:
  where:
                                                  (Eq.7-1)

                   Mass emission rate of species i (g/sec);
       A      -   Area of emitting source (cm2);
       D,      -   Diffusivity coefficient of species i through
                   cover material (cm2/sec);
       X       -   Cover thickness (cm); and
       Cy-Cy  -   Concentration gradient of species i(g/cm3).

 Therefore, covers reduce VOC emission rates by:

   1.   Decreasing diffusivity coefficientrelativetoair(viachemi-
       cal interactions and soil temperature reductions); and
   2.   Increasing required VOC diffusion path (x).

   Some cover materials (e.g., sawdust, straw) are tilled into the
 contaminated soil as an anchoring mechanism. This practice
 results in a soil/cover layer with a higher porosity than the soil
 alone, resulting in increased  VOC emission rates. The major
 components typically required to apply the various cover mate-
 rials are listed in Table 7-2.

 7.13   Applicability to Remediation Technologies
   The applicability of the various cover materials is dependent
 on site characteristics (terrain, vegetation,  access, and contami-
 nated media) and on the desired PM/VOC control efficiencies
 required. The advantages/ disadvantages and applicable reme-
 diation technologies of various cover materials are given in
 Tables 7-3 and 7-4, respectively. Also, some specific character-
 istics of various geomembranes are given in Table 7-5.

 7.1.3   Range of Effectiveness
  Parameters that influence the effectiveness of cover materials
 to control VOC/particulate matter emissions are presented in
Table 7-6. Reported PM/VOC control efficiencies for various
cover materials are presented  in Table 7-7. These control effi-
ciency ranges should be used only as a guide since methods used
in determining these efficiencies, site characteristics, and cover
 application procedures vary from site to site. Information about
 the permeability of various polymeric materials to specific liquid
 VOCs is available for gloves and other personal protective
 equipment (Radian, 1992); these data can be extrapolated for
 selecting soil covers.

 7.1.4    Sizing Criteria/Application Rates
   The amount (depth, thickness, etc.) of cover material required
 to achieve a given control efficiency is not well defined in the
 literature. However, there are general sizing guidelines reported
 in the literature that are presented in Table 7-8.

 7.1.5    Cost Estimating Procedure
   Costestimates of implementing cover-based VOC/PMcontrol
 measures are presented in Table 7-9. Caution should be exercised
 when using these cost estimates, since costs are highly dependent
 on the site characteristics, labor costs, weather conditions, and
 the availability of specific cover materials at each site.

 7.2      Foams
 7.2.1   Process Description
  Modified fire-fighting foams are commonly used to control
 PM/VOC emissions during the remediation of hazardous waste
 sites. Suppression of PM/VOC is accomplished by blanketing the
 emitting source (liquid, sludge, or soil) with foam, thus forming
 a physical barrier to  those emissions. Foams also act to insulate
 the emitting source from the wind and the sun, further reducing
PM/VOC emissions. Some foams are "sacrificial", meaning that
the chemicals compromising the foam will react with specific
VOCs thus further suppressing their emissions. Rusmar and 3M
are the two primary manufacturers of foams for use at Superfund
sites.
                                                            Table 7-2.  Major Components for Cover Material Applications
                                                                Cover material
                                                                                    Major components required
                                                            Soil
                                                            Organic solids
                                                            Polymer sheeting

                                                            Asphalt/concrete
                                                             (paving)
                                                            Road carpet and
                                                             gravel/slag
                        Front end loader
                        Grader
                        Water wagon (optional)
                        Compaction equipment (optional)

                        Front end loader
                        Grader (dependent on material)
                        Tilling equipment (optional)
                        Water wagon (optional)
                        Anchoring net

                        None

                        Grader
                        Front end loader
                        Paving application equipment
                        Compaction equipment
                        Base material

                        Grader
                        Front end loader
                        Base material
                        Compaction equipment
                                                       102

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Table 7-3.   Advantages/Disadvantages of Cover Materials

     Cover material                   Advantages
                                                 Disadvantages
Soils


Organic solids





Asphalt/concrete





Road carpet and gravel/slag
 Polymer sheeting
    Inexpensive
    Easy to apply
    Equipment readily available
    Inexpensive
    Easy to apply
    Equipment readily available
    Long working life
    Equipment readily available
    Cheaper than asphalt/concrete
    Long working life
    Applicable to low traffic volume areas
    Allows contaminated soil from spillage
    and "track-out" to be washed beneath
    road carpet

    100% particulate emission control
    No erosion potential
    Carbon  black addition can limit
    photodegradation
    Conversion of area source to a
    point source
    Creates more contaminated soil
    Subject to erosion   -
    No particulate or VOC control for working face
    Material availability location dependent
    Often requires anchoring to reduce erosion
    No particulate or VOC control for working face
    Combustible
    Creates more contaminated soil

    Expensive
    High maintenance
    Extensive preparation required
    Limited to high traffic volume or permanent traffic pattern
    areas

    Higher maintenance than paved roads
    Extensive preparation required
    Subject to erosion
    Limited tear resistance
    Limited chemical resistance
    Photodegrades easily

    Must be anchored to surface

    No particulate or VOC control for working face
 Table 7-4.  Cover Materials vs. Applicable Remediation Technologies


    Cover material
 Applicable remediation
      technology
              Qualifications
 Soils
 Organic solids
1.   Materials handling
    -  Storage piles

    -  Unpaved roads
    -  Inactive sites*
                                 2.   Bioremediation


                                 3.   Solidification/stabilization

                                 4.   On-site incineration
1.    Materials handling
     -  Storage piles
                                      - Inactive sites*



                                 2.   Bioremediation

                                 3.   Solidification/stabilization


                                 4.   On-site incineration
Daily cover may be applied to active storage piles,
however soils more applicable to inactive storage piles. •
High erosion potential. Best to use "tight1 soils (e.g., clay).
Soils must be uniformly applied and deep enough to prevent
erosion from exposing contaminated soil.

Well compacted soils may limit biological growth by limiting
moisture loading.

Increases soil to be treated.

Increases soil to be treated. Also decreases Btu content of
contaminated soil.
Impractical for active storage piles unless "anchoring" is not
required.

Some materials require anchoring via a net or tilling into soil
to prevent erosion.
                                          May add nutrients to soil (e.g., organic sludges).

                                          Applicable only for small grained organic solids (e.g.,
                                          sawdust, sludges).

                                          May increase Btu content of contaminated soil.
                                                                                                                             (continued)
                                                                  103

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  Tablo 7-4.  (continued)
     Cover material
 Applicable remediation
 	technology
                                                                                  Qualifications
  Asphalt/Concrete
  Road Carpet and Gravel/Slag
  Polymer Sheeting
1.   Materials Handling
     -  Unpaved Roads*
1.   Materials Handling
     -  Unpaved Roads*

1.   Materials Handling
     -  Storage Piles*

     -  Inactive sites*

2.   In-S!tu Thermal Treatment

3.   Sol| Vapor Extraction

4.   Bioremediation
 " Typical use of cover materials. Other listed uses are less common.
                                                                     Applicable for permanent traffic pattern areas (>100 passes/
                                                                     day).
                                                                     Applicable to permanent and temporary traffic pattern areas.
                                                                     Applicable to inactive storage piles.

                                                                     Inactive areas may require extensive pre-applicatlon
                                                                     procedures (I.e., grading, base material, weed control).
                                                                     May be used to convert area source to a point source if
                                                                     liners can withstand the heat.
                                                                     May be used to minimize/control infiltration of ambient air.

                                                                     May reduce biological activity dues to decreased moisture  •
                                                                     loading and oxygen transfer impairment.
 Tablo 7-5.  Synthetic Cover C haracterlstlcs1
       Synthetic material
               Chemical resistance
 Weather     Gas permeability
resistance        resistance      Tear resistance
 Polyethylene
High density polyethylene (HOPE)

Low density polyethylene (LDPE)

Very low density polyethylene (VLDPE)

Linear Low Density Polyethylene (LLDPE)

Polyvlnyl chloride (PVC)

Chlorosulfonated polyethylene (CSPE)

Ethyleno Inlerpolymer alloy (EIA)

Inorganics
Organlcs
Inorganics
Organics
Inorganics
Organics
Inorganics
Organics
Inorganics
Organics
Inorganics
Organics
Inorganics
Organics
Good
Good
Good
Poor
Good
Good
Good
Good
Good
Poor
Good
Poor
Good
Good
Excellent

Poor

Excellent
.{
Excellent

Poor

Good

Good

Excellent

Poor

Excellent

Excellent

Good

Good

Good

• Good •,.

Poor

Good

Good

Good

Good

Good

' Source: Landrelh, 1988 ~ ~~ 	 —
  Foams are generally classified  as either long-term (stabi-
lized) or temporary foams. Temporary foams are effective at
controlling PMTVOC emissions from 1-24 hours, at which time
25% or more of the water incorporated in the foam will have
been released ("quarter drainage time"). Long-term foams ei-
ther contain a stabilizing  agent incorporated into  a short-term
foam (3M products) or are comprised entirely of proprietary
agents (Rusmar Products). Long-term foams will form an elas-
tomeric membrane upon setting (1-2 min)' which is the primary
mechanism of PM/VOC control. Generally the useful life of a
long-term foam is from several days to several months.
                                   Foams generally are produced by pressurizing a mixture of
                                proprietary foam concentrate/water solution through an air-aspi-
                                rated or air-injected foam nozzle; a schematic of this system for
                                3M products is shown in Figure 7-1. However, the long-term
                                foams produced by Rusmar do not require dilution with water.

                                   Two important indicators of foam quality in relation to vapor
                                control are the "expansion ratio" and the "quarter drainage time".
                                The expansion ratio is adimensionless number that expresses the
                                ratio of the volume of foam to the volume of foam concentrate that
                                                           104

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Table 7-6.  Parameters Influencing Cover Material Effectiveness

        Cover material	Parameter	Comments
Soil



Organic solids




Asphalt/gravel



Polymer sheeting
- Porosity
- Moisture content
- Depth

- Porosity
- Moisture content

- Depth

- Road base
- Maintenance
- Surface cleaning

- Liner material

- Liner thickness
Decreased porosity -» increased VOC control.
Increased moisture -»increased VOC/PM control.
Increased depth ->• increased VOC/PM control (to a maximum).

Decreased porosity -»increased VOC control.
.Increased moisture content -* increased particulate/VOC control and decreased
erosion due to wind (only for small grained solids).
Increased depth -»increased VOC/PM control (to a maximum).

Stable road base -> decreased maintenance required.
Well maintained road will limit spillage.
Frequent cleaning will limit PM emissions due to spillage and "track-out."

Liner material influences diffusivity coefficient of various VOCs with respect to liner.
Also determines susceptibility to photodegradation.
Thicker liner -+ increased resistance to VOC diffusion, puncture, and tear.
 Source: Landreth, 1983.
 Table 7-7.  Cover Material Control Efficiency Ranges
Cover material
Soils

Organic soils

Asphalt/concrete
Road carpet
Gravel/slag
Polymer sheeting

Pollutant
PM
VOCs
PM
VOCs
PM
PM
PM
PM
VOCs4

Control
efficiency
(%)
-100
92-99.8
852
NR
85-99
90
45
30-50
100
90

Notes
Theoretical1
1" and 40" soil layer on an inactive site
Inactive storage piles2
	
99% with frequent cleaning
Calculated3
—
Gravel/slag on unpaved roads
Theoretical
Polyethylene liner for hexachlorobenzene
emission control
Source
U.S. EPA, 1988a'
Vogel 1985
U.S. EPA, 1987a
~
U.S. EPA, 1987a
U.S. EPA, 1987b
U.S. EPA, 1987a
U.S. EPA, 1987a
Vogel, 1985

  NR  =  Not Reported
  1  Theoretical based on zero wind/water erosion of soil layer.
  2  Paniculate control efficiencies for inactive storage piles/sites are equivalent (EPA, 1989).
  3  Calculated based on AP-42 emission factors for paved and unpaved roads (U.S. EPA, 1985b).
  4  Some VOC diffusivity coefficients for a 20 ml PVC liner are reported by Springer, et al., 1986.
 Table 7-8.  Cover Material Sizing/Application Guidelines

    Cover material               Pollutant	
                                            Sizing Guidelines
  Soil
  Organic solids

  Asphalt/concrete
  Road carpet and gravel/slag
  Polymer sheeting
      PM           Apply enough soil to insure even application and to prevent exposure of contaminated soil due to
                    erosion of clean soil layer.
     VOCs          Sizing is dependent on moisture content and porosity of soil. Assume linear relationship from
                    data presented in Table 7-7.
      PM           Apply organic solids to the point that no emissions are measured.
     VOCs          None currently available.
      PM           Follow accepted civil engineering guidelines for road construction using asphalt or concrete.
      PM           Follow accepted civil engineering guidelines for road construction using gravel or slag.
      PM           Surface roughness will determine liner thickness required.
     VOCs          VOCs to be controlled will determine liner material to be used. Contact manufacturer for specific
                    information.	
                                                                    105

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  Table 7-9. Cost of Implementing Cover Based Area Control Measures
      Cover material
           Cost (1992$)
Equipment1              Labor/materials
  Backfill dirt                             2.0 m3
  Clay                                  1.0m3
  Rood baso, road carpet, and grave-!'         3-6/m
  AsphaH, road base8                      6-12/m
  Wood fibers with plastic netting3             0.5/m2
  Polymer sheeting                        1.0/m2
                           15/m3
                           15/m3
                          4-10/m
                        200-300/m
                          0.5/m2
                          1.0/m2
    Means, 1991; Vendor
    Means, 1991; Vendor
    Means, 1991; Vendor
    Means, 1991; Vendor
Means, 1991; U.S. EPA, 1988b
          Vendor
  1  7.5 m wkte and 0.15 m gravel.
  J  7.5 mwkfo and 0.10m asphalt.
  1  Wood liber depth not stated.
  4  Assumes material not already on site.
                   Temporary IFoam
                                                                         Stabilized Foam
                                   Pump
                                   pressurized
                           Air- aspirating
                           noxzle
                   Temporary foam
                                                          Educt or
                                                          pressure inject
                                   Stabilized foam
                                  (gels in 1-2min.)
            Source: Aim, etal., 1987

 Figure 7-1. Production of temporary and long-term 3M foams.
produced the foam. Expansion ratios are generally defined as
follows:

  • High-expansion: greater than 250:1;
  • Medium-expansion: between than 20-250:1; and
  • Low-expansion: less than 20:1.

  High-expansion foams can be generated only by using high-
expansion surfactant foam concentrates in combination with
special foam-generating equipment. However, low- and me-
dium-expansion foams can be generated using various combina-
tions of foam types and foam nozzles. For example, a given brand
of foam concentrate may produce a medium-expansion foam
                       with one nozzle and a low-expansion foam using a different
                       nozzle. Another brand of foam may produce a medium-expan-
                       sion foam with both nozzles.

                         The term "quarter drainage time" refers to the time it takes for
                       a foam to release 25 percent of the total liquid incorporated into
                       the foam. Long quarter drainage times are indicative of stable
                       foams, which are capable of suppressing vapors for long time
                       periods before reapplication is necessary. High-expansion foams
                       exhibit the longest quarter drainage times, often exceeding one
                       hour. However, these foams may be blown away easily under
                       windy  conditions.  Medium-expansion foams exhibit quarter
                       drainage times exceeding 15 minutes, but usually less than 30
                                                         106

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minutes. Quarter drainage times for low-expansion foams gener-
ally range between 3 and 12 minutes.

  The major components of a foam PM/VOC suppression sys-
tem are as follows:
    Foam concentrate;
    Water (subject to foam requirements);
    Foam concentrate bulk storage tank; and
    Foam generating/distributing unit
    Manifold distribution
    Hand-line distribution.
  A list of foams by type, brand name, manufacturer, and useful
lifetime is presented in Table 7-10.

7.2.2   Applicability to Remediation Technology
  The advantages and disadvantages of using foams to control
PM/VOC emissions are  outlined in Table 7-11. Remediation
technologies compatible  with foam PM/VOC suppression sys-
tems are listed in Table 7-12. Foams are most commonly used as
temporary covers to control emissions during excavation, dredg-
ing, and other materials handling operations.

7.2.3   Range of Effectiveness
   Several parameters that influence the effectiveness of foam
systems to control PM/VOC emissions are given in Table 7-13.
                                 Reported control efficiencies for foam based systems as a func-
                                 tion of time, foam type, and contaminant to be controlled (PM or
                                 VOC) are given in Table 7-14.

                                 7.2.4    Application Rates
                                    Prior to applying foam, the concentrate must be diluted with
                                 water. Dilution ratios (watenconcentrate) can range from 0 to
                                 16:1. The manufacturer should be contacted to determine the
                                 appropriate dilution ratio required.

                                    Long-term foams are generally applied to depths of one-two
                                 inches, while temporary foams are generally applied to depths of
                                 two to  three inches. The method of application, hand-line or
                                 manifold distribution systems, will depend on the tppography
                                 and media characteristics (i.e. liquid, solid, sludge). Hand-line
                                 systems are capable of shooting foam 30 to 200 feet. Manifold
                                 distribution systems are capable of delivering foam at a rate of
                                 roughly 100 mVmin.

                                    Currently, no empirical relationships exist to predict the PM/
                                  VOC control efficiency of foam suppression systems. Therefore
                                  it is suggested to either use the data presented in Table 7-14 or
                                  conduct pilot scale testing at the site to be treated.
  Table 7-10. Commercially Available Foams for PM/VOC Emissions Control

  Foam type	Brand name	;	Manufacturer
                                                                    Useful lifetime
  Temporary


  Long-term
     FX9162
      AC645

FX9161/9162 mixture
   AC900 series
  3M
Rusmar

  3M
Rusmar
 0.5-1.0 hours
 12-24 hours

   1-7 days
up to 5 months
   Table 7-11. Advantages/Disadvantages of Foam Systems to

                 Advantages                	
                                                       Control PM/VOC Emissions
                                                     Disadvantages
   100% Control of PM emissions achievable

   Effective control of VOC emissions
   Easy to apply                       ,
   Specialized foam application units available
   Allow control of working face - temporary foams
   Applicable to liquid, sludge, and solid media
   Reduced amount of material to be decontaminated
     relative to soil covers                 .
   Long-term foams forming elastomeric membrane
    reduce water infiltration-hence minimize leaching
                                Ca and Mg hardness of dilution water will adversely affect useful
                                lifetime
                                May not work well on steep slopes
                                Temporary foams are easily blown/washed away by wind/water.
                                Materials handling problems due to water in foam
                                Possible that foams will react adversely with VOC's to be controlled
                                Difficult to apply on windy days
                                Foam itself may off-gas


                                Moderately expensive
                                Reapplication required to maintain PM/VOC suppression	
                                                           107

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 Table 7-12. Applicable Uses of Foams by Remediation Technology
 Remediation technology	Foam type
                                             Qualifications
 - Inactive sites/storage piles
 - Active storage piles
 - Dump cycle

 - Excavation

 - Incineration
 - Solidification/stabilization
 - Bforemediation
 Long-term
Temporary
Temporary

Temporary
   Both
   Both
   Both
Foam must be compatible with VOCs to be controlled.

May use manifold distribution systems on open, flat, and solid terrain,
otherwise must use hand-line distribution systems
Slope of storage piles must be gradual so foam will not run off.
Place foam in truck to be loaded then add contaminated material. Because
operators can't see foam level, they must know how much material they can add
before foam overflows.
To maintain continuous control of PM/VOC emissions, foam must be reapplied to
areas as it is removed during excavation.
Water content of foam may preclude incineration of contaminated material.
Foam may be incompatible with process.
Possible limits on biological activity due to impairment of water and oxygen
transfer to active biological zone.
 Tabta 7-13. Parameters Influencing Effectiveness of Foam-based PM/VOC Suppression Systems
	Parameter	Comment
 Quarter drainage time
 Wind Speed

 Precipitation

 Surface roughness
 Expansion ratio
 Temperature
 Surface activity
 Contaminant VOC characteristics
  The longer the quarter drainage time the longer the foam will be useful.
  Wind speeds greater than 10 mph preclude the application of foams (U.S. EPA, 1986a)
  High wind speeds will blow away foams already applied, except for long-term foams which have formed
  an elastomeric membrane.
  Rain will tend to wash foams away, except for long-term foams which have formed an elastomeric
  membrane.
  For some surfaces (i.e., areas covered with shrubs), foams can not be applied evenly.
  The higher the foam expansion ratio the longer the quarter drainage time. Also the higher the foam
  expansion ratio, the more susceptible it is to being blown away.
  Increased temperatures result in decreased quarter drainage times (U.S. EPA, 1989).
  Increased surface activity (i.e.  travel) will decrease effectiveness of foam systems.
  VOCs that are reactive with chemicals comprising foam material will degrade foam effectiveness and
  may produce undesirable compounds.  	
Table 7-14. Reported PM/VOC Control Efficiencies Using Foam Suppression Systems
Foam type
NR
NR
Long-term


Temporary





Long-term



NR - Not reported.
Contaminant
PM
PM
VOC
Paraffins
Olefins
Aromatics
VOC
Paraffins

Olefins

Aromatics

VOC
VOC
VOC
VOC

Control
efficiency (%)
92
74
100
100
99
95
73
90
64 '
99
79
99
91-97
100
100

Time since
application
Continuous
Continuous
24 hours
24 hours
24 hours
20 minutes
2 hours
20 minutes
2 hours
20 minutes
2 hours
7 days
7 days
7 days
7 days

	 	 Comments 	
10.5 ft3 /ton material
8.4 ft3 /ton material
6:1 Expansion ratio 1 inch foam


6:1 Expansion ratio 1 inch foam





„ 	
2-3 inches
2-3 inches
1 inch
t
Source
U.S. EPA, 1989
U.S. EPA, 1989
Aim, 1987


Aim, 1987





Radian, 1991
Schmidt, 1992
Schmidt, 1992
U.S. EPA, 1991

                                                              108

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7.2.5   Cost Estimating Procedure
  Costs for various foam types are given in Table 7-15. These
costs are a function of the area to be treated at the application
depths recommended by the manufacturer.

Table 7-15. Foam Costs
Foam type
Temporary
Long-term
Brand name
FX9162
AC645
FX91 62/91 61
AC904
AC912 -
AC918
AC930
Costs ($/m3)
1.10
0.54-0.86
3.80
1;.30-1.94
1.94-2.70
2.70-3.77
3.77-5.28
Source
Vendor (3M)
Vendor (Rusmar)
Vendor (3M)
• Vendor (Rusmar)
Vendor (Rusmar)
Vendor (Rusmar)
Vendor (Rusmar)
  Costs for foam application units range from $8,000 to $12,000
per month for manifold application units (including bulk storage
tanks) and $3,250 to $7,750 for hand-line application units
(Rusmar, 1992). Small 3M application units can be rented for
about $660 per week; about $500 of ancillary equipment is also
required.

7.3      Wind Screens
7.3 .1   Process Description
  Wind screens can be used to reduce PM emissions from storage
piles, excavation sites, and other area sources. The principle is to
provide an area of reduced wind velocity that allows settling of
the large particles and reduces the particle flux from the exposed
surfaces on the leeward side of the screen. Wind screens also
provide limited control of VOC emissions by increasing the
thickness of the laminar film layer (stagnant boundary layer) on
the leeward side of the screen. In addition, wind screens reduce
soil moisture loss due to the wind, resulting in decreased VOC
and particulate matter emissions.

   Generally wind screens are porous and constructed of plastic
materials. Solid wind screens are not as effective, and are thus
rarely used, because they create a turbulent zone immediately
behind the  fence which increases PM/VOC emissions in this
 area. A diagram of the effect of wind screens on wind speeds is
provided in Figure 7-2.

 7.3.2   Applicability to Remediation Technology
   The advantages and disadvantages of wind screen systems to
 reduce PM/VOC emissions are presented in Table 7-16.

   Wind screens are compatible with all remediation technolo-
 gies involving contaminated materials handling operations (e.g.,
 excavation, storage piles, and inactive sites). The qualifications
 for using wind screens with specific materials handling opera-
 tions are outlined in Table 7-17.

 7.3.3   Range of Effectiveness
   Parameters influencing the effectiveness of wind screens to
 control particulate/VOC emissions are listed in Table 7-18.
 Reported PM/VOC control efficiencies  achieved with  wind
 screens are given in Table 7-19. In general, wind screens provide
 approximately 15% control of total suspendedparticulates (TSP)
than PM10 (U.S. EPA, 1987b). Also, particulate matter control
efficiency for relatively flat active surfaces is expected to be
similar to that observed for active storage piles.

7.3.4   Sizing Criteria/Application Rates
  Wind screen sizing for various materials handling operations
is outlined in Table 7-20. In addition, crude empirical models
have been developed to describe particulate and VOC emissions
reductions. To predict VOC control efficiency, the following
equation applies:
                                                              Efficiency (%)  =
                              xlOO
(Eq.7-2)
  where:
      SR   =  Surface Roughness (m); and
      SH   =  Screen Height (m).

To predict PM control efficiency, use the following model:
  Efficiency (%)  = (l - (1 - WSR)U) x 100       (Eq. 7-3)
  where:
      WSR =  Mean wind speed reduction due to wind screen
                (fraction). .
                                                  V
  Unfortunately this model requires that the mean wind speed
reduction due to the wind screen be known. This can either be
measured or based on estimates provided by the vendor.
                  i
7.3.5   Cost Estimating Procedure
  Capital costs for wind screens vary with the type of control
desired (VOC or PM) and the operation requiring control (e.g.,
inactive sites, excavation, etc.). Costs as a function of pollutant
to be controlled and operation requiring control are outlined in
Table 7-21.

7.4     Water Sprays
 7.4.1   Process Description
   Water sprays are used primarily to control PM emissions. The
control mechanism is the agglomeration of small particles with
larger particles or with water droplets. Also, water added to the
 soil will cool the  surface soil  and  will decrease the air-filled
porosity of the soil. These actions resultin an initial displacement
 of VOCs followed by a decrease in VOC emissions until the
 water evaporates.

   Typically, water is applied with mobile water wagons; how-
 ever, it also may be applied via fixed perforated pipes. Fixed
 systems for water application are  limited to long-term fixed
 emission sources (e.g. conveyor belts, long-term storage piles,
 fixed loading areas, "track-out" elimination sites). The major
 components of water spray systems are listed in Table 7-22.

 7.4.2    Applicability to Remediation Technology
   The advantages/disadvantages of using water as a particulate
 control technique are outlined in Table 7-23. The applicability of
 water spray systems to control area sources of particulate matter
 emissions for various remediation technologies  is outlined in
 Table 7-24.
                                                         109

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JC

I  3
                                                                 (a)
                                              Wind direction
                                               Vertical section
                                               along £ of fence
                                                                                      Fence top

                                                                           % of urfstream velocft
-10H      0        10H      20H     30H     40H
                       Distance In fence heights
                                                                                       50H
                                                                  60H
                          &
                                                                                 Ground plan
                                                                               Wind readings at
                                                                             1 1/3 ft, above ground
                                 -10
                           Source: U.S. EPA, 1986b.
                                                   10H      20H      SOU      40H

                                                       Distance in Fence Heights
                                                         50H
                                                                 60H
 Figure 7-2. Wind velocity pattern above a mown field during a 17 m/sec wind blowing at right angles to a 4.9 m high wood fence 122 m lonq
           of 50% porosity, (a) Side view profile, (b) Plan view profile.
 7A3   Range of Effectiveness
   Water spray  systems are an effective control measure for
 particulate matter emissions. However, they are not recom-
 mended for VOC emissions control, unless they are applied with
 soil cover materials followed by compaction.

   Parameters that influence the performance of water spray
 systems are outlined in Table 7-25. Particulate matter control
 efficiencies for various water application rates and intensities
 reported in the literature are presented in Table 7-26. Particulate
 matter control efficiencies for relatively flat active surfaces are
 expected to be similar to that observed for active storage piles.

 7.4.4    Sizing Criteria/Application Rates
  In general, the water loading and application rates presented in
Table 7-26 can be used to obtain the reported particulate matter
control efficiencies. However, predictive equations have  been
                                  developed  to estimate particulate matter control efficiencies
                                  obtainable for water spray systems applied to unpaved roads.
                                  Table 7-16. Advantages/Disadvantages of Wind Screen Systems
                                          Advantages
                                                                Disadvantages
                                  Inexpensive

                                  Easy to install

                                  Limits site access

                                  Obstructs view of site

                                  Easy to relocate
                                                       Limited VOC control.

                                                       Limited effective control area.

                                                       Limited practical screen height due to
                                                       construction and stability problems.
                                                       Easily damaged.

                                                       Maximum achievable particulate control
                                                       efficiency, approximately 90%.
                                                           110

-------
Table 7-17.  Applicable Remediation Technologies

Materials handling operation
                                     Qualifications
       Storage piles
       Inactive sites
       Excavation areas
       Dump cycles
         Pile height must be controlled. Can completely enclose inactive piles, while
           active piles can only be surrounded on three sides, one side open for
           vehicle  access.
         Large inactive areas require either taller wind screens or many parallel wind
           screens to control emissions effectively.
         Can only enclose three sides, one side open for excavation equipment.
           Screens must be moved  as excavation site moves. VOC control not
           possible.
         Screen height must be greater than dump height. VOC control not possible.
Table 7-18.  Parameters Influencing Wind Screen Effectiveness
                   Parameter
                                                                          Influence
Wind screen porosity

Wind direction with respect to wind screen

Wind screen height
Soil silt content
Solid wind screens form turbulent boundary layer on leeward side thus increasing
  emissions. Most effective wind screens have 50% porosity.
Wind direction influences the size of the protected area. Area of protection is greatest
  for perpendicular winds to the screen, length and least for parallel winds.
Zone of wind velocity reduction is directly proportional to wind screen height.
As soil silt content increases, wind screen particulate control efficiencies decrease.
 Table 7-19.  Reported PM/VOC Control Efficiencies Using Wind Screens
                                           Control efficiencies
Area source VOCs
Storage pile 80






Inactive sites 80
Particulates
48-97
75-80
30-80
75 0"SP)
60 (IP)
0-92 (TP)
64-88
—
Comments
Theoretical
Measured
Theoretical
Measured
Measured
Measured
Measured
Measured
Measured
Source
Vogel, 1985
U.S. EPA, 1989
U.S. EPA, 1987b
U.S. EPA 1987b
U.S. EPA, 1987b
U.S. EPA, 1987b
U.S. EPA 1986b
U.S. EPA, 1988a
Springer et al., 1986
TSP = Total suspended particulates (<39 urn);
IP = Inhalable particulates (<1 5 pm); and
TP = Total particulates.
                                                                  111

-------
 Tabta 7-20.  Wind Screen Sizing

   Materials handling operation
                                                                    Wind screen sizing
         Storage Piles


         Dump cycles

         Excavation

         Inactive sites
                                           Screen length = five times pile diameter.
                                           Screen/pile distance = two times pile height.
                                           Screen height = pile height.                                 '

                                           Screen height > 1 ft. above bucket drop height.

                                           Screen/site distance = two times screen height.

                                           Wind screen should be placed perpendicular to prevailing wind direction.
                                           Distance between parallel wind screens = four to ten times screen height.
 Table 7-21.  Wind Screen System Costs
         Type of control
                                                 Operation requiring
                   Control
                                                                          Cost
                                                                                                      Source
 voc

 Paniculate matter
          Inactive surface impoundment

                Inactive sites'
                Storage piles2
                Excavation 3
 0.7-1.4$/m 2 impoundment area

  0.6-13 $/m 2 of inactive area
     721 $/m2 of pile area
  11 $/m 2 of excavation area
      U.S. EPA, 1991

Vendor data/sizing guidelines
Vendor data/sizing guidelines
Vendor data/sizing guidelines
  IrKSrt^Sre181" "** k""8 '" avai{able to S8Cure wind screen a9alnst (valid for sma" areas)- Cost Per "™* meter for wind screen is about $40,
                                                                                                   not
1 Assumes conically-shaped storago pile of roughly 10m diameter.
* Assumes 60m diameter excavation site and 1.8m high wind screen around 2/3 of site.
                  CAVO  -  100 -
                                  0.8 pdt
                                  (Eq.7-4)
   where:
       C*
       P

       P

       P

       d
       i
       t
 Average control efficiency (%);
 Potential average hourly daytime evaporation
 rate (mm/hr); also
 0.0049 x (value in Fig. 7-3) for annual condi-
 tions; or
 0.0065 x (value inFig. 7-3) for summer condi-
 tions;
 Average hourly daytime traffic rate (hr1);
 Water loading rate (L/m2); and
 Time between applications (hr).
  For storage piles and inactive sites, the particulate matter
control  efficiency achieved can be determined from  the soil
moisture content before and after water application as shown in
Equation 7-5.
                                  xlOO
  where:

      sii
      A,B
                                 (Eq.7-5)
Instantaneous control efficiency (%);
Soil moisture content (weight %); and
After, before water application, respectively.
 7.4.5   Cost Estimating Procedure
   For mobile water spray systems, capital costs are estimated to
 be $23,000/water wagon per year while operating and mainte-
 nance (O & M) costs (fuel, water, labor, truck maintenance) are
 estimated to be $44,000/water wagon per year. Furthermore, the
 number of water wagons required can be estimated by assuming
 that a single truck applying 1 L/m2 can treat roughly one square
 mile per  hour (approximately 11,000 m2). Capital and O&M
 costs for fixed water systems will vary with the type of emission
 source to be controlled (e.g.,  "track-out", excavation, loading
 operations) and the amount of plumbing required.


 7.5    Water Sprays with Additives
 7.5.1   Process Description
  Water additives can be classified as hygroscopic salts, bitu-
 mens, adhesives, or surf actants and are primarily used to reduce
 particulate matter emissions. The processes by which these
 additives act to reduce particulate matter emissions are outlined
 in Table 7-27. Some common water additives and their classifi-
 cation are listed in Table 7-28.

  Water additives generally are applied topically;  however,
 some additives can  also  be tilled into the soil. Components
required for topical  application include those  used  for water
spray systems (see  Section 7.4) and  a storage tank for  the
undiluted  chemical. Tilling of the water additives into the soil
also requires tilling equipment.
                                                          112

-------
7.5.2   Applicability to Remediation Technology
  The advantages/disadvantages of using water additives as a
participate matter control technique are outlined in Table 7-29.
Remediation technologies that are compatible with water addi-
tives are listed in Table 7-30.

7.5.3   Range of Effectiveness
  Parameters that influence the performance of water additives
are presented in Table 7-31. Paniculate matter control efficien-
cies for various water/additive mixtures reported in the literature
are reproduced in Table 7-32. Paniculate matter control efficien-
cies for relatively flat active surfaces are expected to be similar
to those observed for active storage piles.

7.5.4   Application Rates
  In general, the water/additive dilution, application intensities,
and frequencies presented in Table 7-32 can be used to obtain the
reported paniculate matter control efficiencies. Paniculate mat-
ter control efficiencies for hygroscopic salt/water mixtures can
be estimated from the predictive equations presented earlier for
water spray systems (Section 7.4).

  For bitumens and adhesives, time  averaged PM10 control
efficiencies as a function of additive "ground inventory" can be
determined directly from Figure 7-4. The term "ground inven-
tory" is a measure of residual effects from previous applications.
Ground inventory is found by adding together the total volume of
additive concentrate (not solution) since the start of additive
application per surface area treated. Also, AP-42 emission fac-
tors for paved roads can be used to conservatively estimate PM
 Table 7-22.  Major Components of Water Spray Systems
   emissions (1.5 to 2 times actual emissions) from unpaved road
   surfaces treated with bitumens/adhesives.

     Typical dilution ratios and application rates (bitumens and
   adhesives) used in the iron/steel industry for treatment of un-
   paved roads are applicable and are presented below.

     Paved road "housekeeping" techniques can be used on roads
   treated with bitumens/adhesives after the ground inventory ex-
   ceeds approximately 0.9 L/m2 (U.S. EPA, 1989). These "house-
   keeping" techniques  will limit emissions due  to spillage and
   "track-out" and will reduce required application frequencies.

     Tilling of bitumens/adhesives into the top 7.6  cm (3 in.) of the
   soil followed by compaction resulted in paniculate matter con-
   trol efficiencies of 33 to 95% five mqnths after application (U.S.
   EPA, 1987b).

   7.5.5  Cost Estimating Procedure
     Water additives costs include the costs associated with water
   spray systems (Section 7.4.5) and also include the cost of addi-
   tives and storage tanks for the additives. Storage tank costs will
   vary depending on the size of the operation, the water/additive
   application rate and  the time between deliveries of additive.
   Some additive costs, by product  name and classification are
   presented in Table 7-33. The dilution ratio, application rate and
   frequency must be determined to predict the cost/ft2.

   7.6     Operational Controls
    7.6.1   Process Description
      Operational controls are those procedures/practices inherent to
   most site remediation projects that can be instituted to reduce
    VOC/particulate matter emissions. These procedures/practices
    include:
         Capital equipment
                                                                   Comment
 Water spray system
           Supply pumps, nozzles, and plumbing
           Flat spray
           Hollow cone
           Water wagon
           Plumbing (plus winterization)
           Control system
           Filtering units
Primarily used for fixed spray systems.
Used for water screens that control particulate emissions from dump cycle.
Used for all other particulate emission sources.
Used for mobile spray systems.
Used for stationary spray systems.
Controls water application rate.            .
Prevents fouling of spray nozzles.
 Table 7-23.  Advantages/Disadvantages of Using Water to Control PM Emissions
         Advantages
                 Disadvantages
 Inexpensive
 Easy to apply
 Well defined models for determining particulate control efficiency
 Equipment availability.
Frequent application is required.     .   •           •      .
May create groundwater contamination via mobilization of contaminant.
Creates material handling problems.
Increases "track-out".
Results in VOC emission spikes.
Availability of water at some sites may preclude its use.
Possible runoff of contaminated water.
                                                           113

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  Table 7-24.  Remediation Technologies Compatible with Water Spray PM Control Systems

1.














2.

3.

4.

5.

Remediation technology
Materials handling
• Storage piles
- Active
- Inactive
• Excavation


• Inactive sites
• Conveyor belt systems
• Unpavcd roads
• Fixed loading areas


• Track-out" elimination sites


Bioremediation

Solidification/stabilization

On-site Incineration

Thermal desorption

Water spray
system


Mobile
Fixed
Mobile


Mobile
Fixed
Fixed
Fixed


Fixed


All

All

All

All

Qualifications - • . , «


Water application rate must be adjusted for exposed area and to
prevent erosion.
Use of hoses. Fixing hoses to excavation equipment is impractical.
Water application rate must be adjusted to present materials handling
problems.
Use of water wagons. Water application must be uniform and
controlled to insure a given application rate.
Water should be applied to underside of conveyor belt.
Unpaved roads should be well graded to insure uniform water
application. Water applied to unpavecl roads will increase "track-out".
Water spray system designed to apply a flat spray, forming a water
curtain around loading area which is two to three feet above material
drop height.
Vehicles pass over sump covered with a metal grate located at site
exit. Water spray directed upwards to wash vehicle undercarriage and
wheels of contaminated soil.
Water may dissolve organic compounds to be biodegraded and
transport them past biological area. Water may also limit oxygen
transport from atmosphere into the soil.
Water spray system should be compatible with waste or stabilization
process used unless soil moisture is >95%.
Water may lower Btu content of soil to the point that incineration is not
possible.
Water may lower Btu content of soil. However, soils having 1 0-15%
moisture exhibit enhanced VOC removal.
 Table 7-25.  Parameters Influencing Water Spray Systems Performance

 	Parameter	                           Influence
 Application rate


 Application frequency


 Meteorological conditions


 Traffic rate
For fixed meteorological conditions and traffic rates the particulate matter emissions are inversely proportional
to the square of the soil moisture content (U.S. EPA, 1988a).

Particulate matter emissions are minimum after water application and rise steadily thereafter until the next
application of water.

Wind, temperature, and humidity influence evaporation rate of water, hence particulate matter control efficien-
cies.

Higher traffic volumes results in higher particulate matter emissions due to increased fines produced.
     Read cleaning practices;
     Seasonal scheduling;
     Vehicle speed control;
     Storage pile geometry/orientation;
     Excavation practices;
     Dumping practices; and
     Soil handling practices.

  Of the above procedures/practices, only road cleaning requires
additional equipment (i.e., broom sweepers, vacuum sweepers,
or water wagons). Road cleaning practices are aimed at reducing
particulate matter emissions from spillage and "track-out," and
                                 can be applied to paved roads and some chemically treated
                                 unpaved roads (see Section 7.5).

                                   Planning site remediations according to the time of year can
                                 reduce overall PM/VOC emissions by1 taking advantage of lower
                                 temperatures and wind speeds and avoiding excessively dry
                                 weather. However, since site remediation is generally a relatively
                                 continual process, seasonal scheduling is only advantageous for
                                 sites which can be remediated within a season or two.

                                   For unpaved roads, particulate matter emissions increase as the
                                 speed of the vehicle increases, all other factors remaining con-
                                                           114

-------
Table 7-26. Reported Particulate Matter Emission Control Efficiencies for Watering Systems
Application
Area source intensity (Urn2)
Unpaved roads




















Storage piles
Loading operations
Above conveyor belt operations

Below conveyor belt operations

Excavation

Dump cycle (area spray)

NR


NR


NR
NR
NR
NR



NR
NR
NR
2.3
0.2
0.2
0.6
1.9
NR
NR
9.51/min

9.51 /min

4.1

4.1

Time since
application (hr)
0.5-4.5


0-1.0


0-0.5
0-0.25
0.3-1.0
1.0-4.8



0.5-2.0
1.0-2.0
0.5-2.0
4.0
1.8
2.0
4.5
2.8
NR
NR
Continuous

Continuous

NR

NR

Particle
size1
TP
IP
FP
TP
IP
FP
TSP
TSP
TSP
TP
IP
PM10
FP
TSP
TSP
TSP
NR
TSP/FP
TSP/FP
TSP/FP
TSP/FP
NR
NR
IP
TP
IP
TP
FP
TSP
FP
TSP
Control
efficiency (%)
96-55
98-50
98-61
69-59
73-61
58-54
88
97
75-25
98-61
98-78
98-79
96-67
77-12
66-31
60-15
50-30
59
69
77
88
25-50
70-90
56
59
81
87
64
42
66
69
Source
U.S. EPA, 1985a


U.S. EPA, 1985a


U.S. EPA, 1985a
U.S. EPA, 1985a
U.S. EPA, 1985a
U.S. EPA, 1985a



U.S. EPA, 1985a
U.S. EPA, 1985a
U.S. EPA, 1985a
U.S. EPA, 1985b
U.S. EPA, 1987a
U.S. EPA, 1987a
.-U.S. EPA, 1987a
U.S. EPA, 1987a
U.S. EPA, 1987b
U.S. EPA, 1987b
U.S. EPA, 1989a
U.S. EPA, 1989a
U.S. EPA, 1989a

U.S. EPA, 1985a

U.S. EPA, 19853

NR = Not reported;
TP = Total particulates;
TSP = Total suspended particulates (<39um); ..
IP m Inhalable particulates (<15Mm);
PM10 = Particulate matter (<10 urn); and
FP » Fine particulates (<2.5um).
slant. Speed reduction reduces the turbulence and energy im-
parted to fine particles, which reduces particulate matter entrain-
ment.

  PM and VOC emissions from storage piles can be minimized
by controlling the placement and shape of piles. When feasible,
the piles should be placed in areas shielded from the prevailing
winds at the site. The pile surface area can be minimized for the
given volume of soil by shaping the pile. The orientation of the
pile will affect the wind velocity across the pile, hence PM/VOC
emissions will be affected.
  Since PM/VOC emissions are proportional to the surface area
exposed, a reduced surface area/volume ratio will minimize
emissions per unit volume of soil excavated. This reduction can
be accomplished by utilizing larger excavation equipment (i.e.,
larger bucket volumes for front end.loaders, bulldozers, and
backhoes).

  Dumping practices which can be employed to reduce particu-
late matter emissions include drop height reduction and loading/
unloading of material on the leeward side of storage piles. By
minimizing the soil drop height,  the energy and turbulence
caused by the falling soil are reduced thus reducing particulate
matter entrainment. VOC emissions will also be reduced.
                                                        115

-------
 Table 7-27.  Additive Processes
          Additive
                                                              Process description
 Hygroscopic salts
 Bitumens/Adhesives
 Surfactant
These compounds adsorb moisture from the air, thereby increasing the soil moisture content.
Act to agglomerate surface soil particles to form a surface "crust".
Act to reduce water surface tension, thereby increasing "wetting" capacity of the water.
 Table 7-28.  Common Water Additives
          Product
                                                                      Manufacturer
         Calcium chloride
         Dowllake, Liquid Dow®
         DP-IO®
         Dust Ban 8806®
         Dustgard®
         Sodium silicate
                                  A. Hygroscopic salts

                                  Allied Chemical Corporation
                                  Dow Chemical
                                  Wen-Don Corporation
                                  Nalco Chemical Company
                                  G.S.L Minerals and Chemicals Corporation
                                  The PQ Corporation
         AMS 2200, 2300®
         Coherex®
         Docal 1002®
         Peneprime®
         Pelro Tac P®
         Resinex®
         Retain®
         Acrylic DLR-MS®
         Bfo Cat 300-1®
         CPB-12®
         Curasol AK®
         DCL-40A. 1801.1803®
         DC-859, 873®
         Dust Ban®
         Flambinder®
         Ltgnosite®
         Norlig A, 12®
         Orzan Series®
         Soil Gard®
                                  B. Bitumens

                                  Arco Mine Sciences
                                  Witco Chemical
                                  Douglas Oil Company
                                  Utah Emulsions
                                  Syntech Products Corporation
                                  Neyra Industries, Inc.
                                  Dubois Chemical Company

                                  C. Adhesives

                                  Rohm and Haas Company
                                  Applied Natural Systems, Inc.
                                  Wen-Don Corporation
                                  American Hoechst Corporation
                                  Calgon Corporation
                                  Betz Laboratoires, Inc.
                                  Nalco Chemical Company
                                  Flambeau Paper Company
                                  Georgia Pacific Corporation
                                  Reed Lignin, Inc.
                                  Crown Zellerbach Corporation
                                  Walsh Chemical
         M070E
         Sterox
Sowco: Paao 45 of U.S. EPA, 1987t>.
                                  D. Surfactants

                                  Mona Industries Inc.
                                  Monsanto Company
                                                             116

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Table 7-29.  Advantages/Disadvantages of Using Water Additives to Control Paniculate Matter Emissions


                   Advantages                                                      Disadvantages
 Easy to apply

 Equipment availability.

 Surfactants reduce water required by 75% for same
   level of control (U.S.. EPA, 1989)

 Less frequent reapplication required than water spray systems.
       Additives may be washed away by rain, thus negating their effects (e.g., salt).

       Additives may react with contaminants present in the soil.

       Additives often contain organic compounds which may vaporize, leading to
       ozone production (U.S. EPA, 1988a).

       Not applicable to unpaved roads that require frequent grading.
       Expensive.
       Application of chemical additives in cool weather may be inadvisable for traffic
       safety reasons (U.S. EPA, 1988a).
       Additives may contribute to water contamination (surface water and groundwa-
       ter).
       Some salts (e.g., CaCL,) are corrosive to vehicles.
 Table 7-30.  Remediation Technologies Compatible with Water Additives
     Remediation technology
          Qualifications
 1.   Materials handling
     • Storage piles (inactive
     • Inactive sites
     • Unpaved Roads
2.   Bioremediation

3.   Solidification/stabilization


4.   On-site incineration
 Same as water spray (see Section 7.4).
 Same as water spray systems.
 Same as water spray systems. Also can use paved road cleaning techniques for
 unpaved roads treated with adhesives and bitumens. This practice reduces particulate
 matter emissions due to spillage and "track-out".

 Same as water spray systems. Also additives may inhibit biological activity.

 Same as water spray systems. Additives may be incompatible with waste or stabiliza-
 tion process used.

 Water may lower Btu content of soil to be treated. However, certain additives may
 increase Btu content of soil to be teated (e.g., bitumens and adhesives).
Table 7-31.  Parameters Influencing Performance of Water Additives
         Parameter
                                                                         Influence
Dilution ratio




Application rate



Application frequency

Meteorological conditions
Vehicle weight, speed, and passes

Unpaved roads base and subgrade bearing strength
Higher dilution ratio results in decreased additive applied for a given water/additive
loading rate. This decreases long-term control efficiency (e.g., 2-3 weeks after
application).

Higher loading rate results in higher particulate matter control. However, this relation-
ship applies only to a point, because too intense an application will produce run-off.

Same as for water spray systems.

Affect required application frequency for a given control efficiency. For example,
freeze-thaw cycles break up crust formed by chemical binding agents; heavy
precipitation washes away water soluble additives like hygroscopic'salts; and intense
solar radiation dries out treated surfaces.  However, light precipitation or high humidity
might improve the efficiency of hygroscopic salts.

Acts to break up crust formed by chemical binding agents.

Low base and subgrade bearing strength  will result in road deformation which will
destroy crust formed by chemical binding  agents.
                                                                117

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Table 7-32,  Reported Partlculate Matter Emission Control Efficiencies for Water Additives

Area source

Additive classification
Unpaved Roads Hygroscopic salts


























Storage piles




Inactive sites















Excavation

Dump cycle













Bitumens/adhesives










Surfactant


Bitumens/adhesives




Bitumens/adhesives















Surfactant 1

Surfactant 1

Dilution
ratio
NR

1:2


1:1

NR


NR


NR



1:8
1:6


1:5
1:0

NR


1:5


1:35

1:2
1:2
1:2
1:12
1:4
1:4
1:4
1:19
1:1
1:1
1:1
1:7
1:3
1:3
1:3
1:11
:1000

:1000

Application
Intensity (L/m 2)
2.3

2.7


0.9

NR


NR


NR



NR
0.9


NR
16.0

NR


3.4


6.8

0.81
0.41
0.20
0.31
1.13
0.57
0.28
1.13
1.13
0.57
0.28
1.13
1.12
0.75
0.37
1.12
3.4

4.1

Time since
application (days)
3-60

90


30-270
RP
93


1-49


14

30

<7
1-2


14
30-270

1-42


60


4

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Continuous

Continuous

Particle
size2
TSP
IP
TSP
IP
FP
TSP
42
TSP
IP
FP
TSP
IP
FP
TP
PM10
TP
PM
TSP
TP
TSP
FP
TP
TSP
IP
TSP
IP
FP
TP
IP
FP
TP
IP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TSP
FP
TSP
FP
Control
efficiency (5)
48
24
95
95
95
46

95
98
88
0-83
0-74
0-80
47-96
60-96 ..
47-90
60-94
91
92-98
91-96
90-97
99
96
57
0-87
0-68
0-85
90
62
62
44
50
94
• 68
36
99
99
96
84
99
99
93
85
100
99
98
87
100
63
70
77
62

Source
U.S. EPA, 1987a






,





U.S. EPA, 1987a










U.S. EPA, 1987C


U.S. EPA, 1987a




U.S. EPA, 1989















U.S. EPA, 1987b

U.S. EPA, 1985a

1 Additfvo concentrate: Water
« TP
TSP
IP
FP
PMM
NR
Total particulate matter






Total suspended pmliculate matter (<38pm);
Inhalable partteulata matter (<15Mm);
Fine particulate matter(<2.5(jm)
Particulate matter (<10 vm)
Not reported


















                                                             118

-------
                                                	100	 '  95	90_
                                                    I        '        1
                                             Mean Annual Class A Pan Evaporation
                                                        (In Inches)     i	
                                               "    '   35  30 Cl.
                                                       -^-T—V-H J'Tntemalional Fate
                                                       - sL \ ""^
                                                         \   ^      	
            Based on period 1946 - 1965
   Source: Buonicore, et al., 1992.

 Figure 7-3.   Annual evaporation data for the contiguous United States.
  Spillage of soil during transport is a consequence of loading
practices and is a primary cause of particulate matter emissions
from paved roads. Minimizing spillage can be accomplished by
covering or enclosing tracks transporting soils increasing free-
board requirements, and repairing trucks exhibiting spillage due
to leaks.

7.6.2   Applicability to Remediation Technology
  The relative advantages/disadvantages of each operational
practice/procedure are outlined in Table 7-34. Road cleaning
practices, seasonal scheduling, and vehicle speed control are
applicable to all remediation technologies, while the other prac-
tices/procedures are applicable to materials handling operations.

7.6.3   Range of Effectiveness
  Reported control efficiencies for some operational practices/
procedures are given in Table 7-35.

7.6.4   Sizing Criteria/Application Rates
  For a target control efficiency, the operational practices/proce-
dures required can generally be determined by using AP-42
emission factors presented in U.S. EPA, 1985b. Operational
practices/procedures  which are amenable to this approach are:
  • Road cleaning practices;
  • Seasonal scheduling;
  • Vehicle speed control;
  • Excavation practices; and
  • Dumping practices.

  Quantification of particulate matter emission controls achiev-
able for soil loading practices and storage pile geometry/orienta-
tion are not possible. However, guidelines are available for each
of these operational control measures.

7.6.5   Cost Estimating Procedure
  For the majority of the operational control measures presented
in this section, the cost is negligible with the exception of road
cleaning equipment and possibly seasonal scheduling. The cost
of seasonal scheduling will vary with  season primarily due to
labor costs and equipment availability. Cost for street cleaning
practices are estimated to be $140 per day per street cleaner and
$66 per day per crew (Means, 1991). The use of larger excavation
equipment to minimize emissions will increase costs to some
extent (Means, 1991).
                                                         119

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        100
                 0.05    0.1    0.15    0.2    0.25
                      Ground inventory (gal/sq. yd.)
                  0.3
 Source: U.S. EPA. 1987c.
 Figure 7-4. Average PM10 control efficiency for bitumen/adhesive
           additives.
 7.7     Enclosures
 7.7.7   Process Description
   Enclosures are used to provide near 100% PM/VOC emission
 control for area sources undergoing excavation and PM/VOC
 emissions control for storage piles. Enclosures used during
 excavation are either self-supported or air-supported structures,
 while those used for storage piles are self-supported structures
 similar to the "beehives" used, to store road salt.

   Enclosures provide a physical barrier between the emitting
 area and the atmosphere and in essence convert an area source
 into apoint source. Prior to releasing the air entrapped within the
 enclosure, conventional point source controls are employed to
 control PM/VOC emissions.

   Self-supported structures consist of a rigid frame covered with
 an all-weather outer skin. The frame is generally constructed of
 light  weight aluminum which may require concrete footings,
 depending on the size of the structure. The outer skin generally
 is constructed of corrugated steel or textile materials. Since self-
 supported  structures do nol: rely  on interior air pressure for
Table 7-33.  Additive Costs

    Additive classification
Typical material cost ($/ft2)
Hygroscopic salt
Bitumens/add esives
Surfactant
      0.02-0.10'
      0.15-0.32 '
        0.002 2
1  Source: U.S. EPA. 1888a.
*  Vendor data at recommended dilution and application rates.
 support, they usually are operated under negative pressure.
 Negative interior pressure prevents PM/VOC emissions via
 entrances/exits and leaks in the structure.

   Air-supported structures consist of an all weather membrane
 that is  supported by positive pressure within the enclosure.
 Because the enclosure is under positive pressure any leaks or
 openings will result in PM/VOC emissions. To counter this, air-
 supported structures often are equipped with air lock systems.

 7.7.2    Applicability to Remediation Technology
   The advantages/disadvantages of using enclosures to control:
 PM/VOC emissions are outlined in Table, 7-36.

   Because enclosures do not alter the physical properties of the
 material to be treated, their compatibility with various remedia,-
 tion technologies is only a function of the enclosure properties
 (size and materials of construction) and the chemical properties
 of the VOCs to be controlled (i.e., reactivity with enclosure
 materials). In general, all materials handling processes (e.g.,
 excavation, loading, storage piles, stabilization processes) emit-
 ting PM/VOC can be controlled using enclosures. The key,
 consideration as to whether or not enclosures are appropriate for
 a given site is how expensive will it be to maintain the tempera-
 ture and air quality within the dome at acceptable levels for
 workers.

 7.7.3    Range of Effectiveness
   The effectiveness of enclosures to limitPM/VOC emissions is
 a function of the enclosure "capture" efficiency and the point
 source control system efficiency. Capture efficiency is a measure
 of the ability of the enclosure to capture the emitting PM/VOC.
 For example, if an air supported structure has a leak due to an
 incomplete seal between the structure and the surface or if the
 skin is torn, then PM/VOC will be emitted to the atmosphere, thus
 lowering the capture efficiency. Point source control system
 efficiency is  dependent  on the particular control system but
 generally is in the range of 95-100%. Reported enclosure control
 efficiencies are presented in Table 7-37.                  *!.

 7.7A    Sizing Criteria/Application Rates
  Enclosures range in size from 30 feet in diameter to 130 feet
 wide x 62 feet tall x unlimited length. For self-supported struc-
 tures wider than 60 feet, footings may be required.  Prior to
 erecting an enclosure, the site may require grading so that the
 slope is less than three percent (Sprung Instant Structures, Inc.,
 1992).

 7.7.5    Cost Estimating Procedure
  The costs of air supported and self-supported enclosures are
given in Table 7-38. Note: The costs presented in Table 7-38 do
not include the costs of gas collection/treatment systems.

7.8     Collection Hoods
7.8.1   Process Description
  Hoods are commonly used to capture PM/VOC emitted from
small area sources (e.g., waste stabilization/solidification mixing
silos, bioremediation reactors) and  route those  emissions  to,
appropriate air pollution control devices. In practice, hoods are
                                                         120

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designed using the capture velocity principle which involves the
creation of an air flow after the emitting source that is sufficient
to remove the contaminated air.

  Three hood  designs that are commonly used are depicted in
Figure 7-5. The selection of hood type will be dependent on the
emitting source characteristics (e.g., source area and accessibil-
ity, emitting air  velocity, surrounding air currents)  and the
required capture efficiency. Major components of a hood exhaust
system are depicted in Figure 7-6.

7.8.2   Applicability to Remediation Technology
  Hoods can be used to capture PM/VOC emissions from ex-situ
waste stabilization/solidification mixing silos and bioremedia-
tion reactors. The use of a hood will be contingent upon access to
the emitting source and upon the area of the emitting source. As
the distance between a source and hood increases, so does the
required total volumetric flow rate of air into the hood to maintain
a given capture efficiency. Since the cost of most air pollution
control equipment is proportional to the volumetric flow rate, a
point is reached where it is not economically feasible to use a
hood. The emitting source area will impact the hood size required
and for canopy and capturing hoods will impact the air flow rate
required to maintain a given capture efficiency. The advantages/
disadvantages of using a hood to capture PM/VOC emissions are
outlined in Table 7-39.
                    7.8.3   Range of Effectiveness
                      Parameters which influence the capture efficiency of hood
                    exhaust systems are given in Table 7-40.

                      Hood PM/VOC capturing efficiencies can be as high as 90 to
                    100%. However, PM/VOC control efficiencies will be a function
                    of both the hood capture efficiency and the air pollution control
                    equipment removal efficiency.

                    7.8.4   Application Rates
                      Hood exhaust systems designs are based on the hood aspect
                    ratio (width/length of hood), the required capture velocity (v),
                    and the distance of the furthest point of the emitting source from
                    the hood centerline (x). Ranges of capture velocities required as
                    a function of surrounding air turbulence and the emitting source
                    are listed in Table 7-41 .The velocities obtained from Table 7-41
                    can then be used in the design, equations presented in Table 7-42.
                    For a more thorough presentation on hood designs, see "Indus-
                    trial Ventilation" (ACGIH, 1980).

                    7.8.5   Cost Estimating Procedure
                      The costs of hood exhaust systems are highly dependent on the
                    volumetric flow rate, the length of ducting required, the hood/
                    ducting materials of construction required (e.g., carbon steel,
                    stainless steel), hood size, and fan size required to move the air.
                    An example of a hood exhaust system cost breakdown is pre-
                    sented in Table 7-43.
Table 7-34.  Advantages/Disadvantages of Operational Practices/Procedures
    Operational practices/procedures
          Advantage
        Disadvantage
Road cleaning practices
Seasonal scheduling
Vehicle speed control
Storage pile geometry/orientation
Excavation practices
Dumping practices


Soil loading practices
Equipment readily available
Easy to operate
No equipment required
Potentially high control of PM/VOC emissions
Inexpensive
Easy to implement
Reduces road maintenance required
Decreases incidence of accidents
Inexpensive

Easy to implement
Inexpensive
Easy to implement

Decreases time to excavate a given volume
Easy to implement
Inexpensive

Easy to implement
Inexpensive
Requires additional equipment.
Broom sweeping may increase particulate
matter emissions.

Stagnant wind conditions may lead to
unacceptable ambient air concentrations at
the work site.
Rigorous timing constraints.

Increases haul time.
May require more vehicles.
Difficult to maintain optimum pile geometry.
Optimum pile geometry may not be possible
due to space limitations.

Requires larger equipment which may
increase excavation cost.
Increased equipment size may not be
practical due to site size constraints.
Increased equipment size may damage
paved roads and increase particulate matter
emissions from unpaved roads.

May increase unloading time.
May decrease volume of soil per haul.
                                                          121

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Tablo 7-35.   Reported PM/VOC Control Efficiencies for Operational Practices/Procedures
Operational practice/procedure
Road cleaning practice
• Vacuum sweeping
• Water flushing
• Water flushing/broom sweeping
Vehicle speed control
Storage pile geometry/orientation
Excavation practices
Dumping practice
Pollutant

PM
PM
PM
PM
PM4
PM4
PM4
Reported control
efficiency (%)

0-58
0-69
0-96
0-80
0-80/60 1
20 2
50 3
Comments

Measured
Measured
Measured
Estimated
Estimated
Theoretical
Theoretical
Source

U.S. EPA, 1989


U.S. EPA, 1987b
U.S. EPA, 1991/Vogel, 1985
U.S. EPA, 1985a
U.S. EPA, 1985a
1  Pilo length Is perpendicular to prevailing wind direction.
*  Calculated from AP-42 Emission Factors, assuming doubling of bucket capacity.
*  Calculated from AP-42 Emission Factors, assuming a 50% reduction in material drop height.
4  Somo VOC control would also occur, but no control efficiency data are available.
  For further guidance in obtaining cost estimates  for hood
exhaust systems, consult Vatavuk, 1990.

7.9     Miscellaneous Controls
  A number of miscellaneous controls for area sources could
theoretically be used at Sur.erfund sites. VOC emissions from
lagoons could be controlled using floating solid objects such as
hollow plastic spheres or rafts, or a floating layer of immiscible
oil  (Springer, et al, 1986). Blankets of nitrogen or other inert
gases are another option. The use of these types of controls at
Superfund sites has not been documented and feasibility testing
certainly would be advisable prior to any full-scale use.
Table 7-36.  Advantages/Disadvantages of Enclosures to Control PM/VOC Emissions

                  Advantages
             Disadvantages
 Near 100% control of PM/VOC emissions

 Conversion of area source Into point source for easier control of PM/
   VOC emissions.

 Limits access to working area.

 Compatible with remediation of soils, sludges, and liquids.

 Does not create additional material to be treated.

 Reduces groundwater and surface water contamination due to
   precipitation.

 Assist thermal treatment of solids by excluding moisture loading rate
   onto soil.
Expensive.

Increased temperatures and PM/VOC concentrations limit the ability to
  work inside enclosure to short-time periods and may require workers
  to use protective apparel. Also specific VOC concentrations must
  not exceed OSHA prescribed IDLH values.

Air supported structures can be damaged by wind.

Some VOCs may damage polymeric skin materials.

Building permits may be required by local municipalities.


Limits to structure size may require structure relocation as excavation
  site moves.

Requires point source PM/VOC controls.

Enclosure may require decontamination following its use.
                                                             122

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Table 7-37.  Reported Enclosure PM/VOC Control Efficiencies
        Contaminant .
Reported control efficiency (%)
        Comment
    Source
          PM/VOC
             PM
          up to 100
           70-99
Material handling operations
    Active storage piles
 U.S. EPA, 1991
U.S. EPA, 1987b
Table 7-38.   Enclosure Costs
          Type of enclosure
        Enclosure rental cost a'b
            ($/month-m 2)
         O&M cost.($/m2).'
     Source
            Air-supported
            Self-supported
            Self-supported
                 5.5
                 19
               4.4-8.5
                NR                U.S. EPA, 1988b
                48        '            Aul, 1992
              1.2-6.5	Sprung Instant Structures, 1992
  The cost of grading and footings are not included.
  If the structure is needed for more than 2 years, purchase of the structure may be more economical than renting.
  O&M costs include the cost of erecting/dismantling the enclosure.
                                                To fan
                                                                        (a)  Enclosures—contain
                                                                            contaminants released
                                                                            inside the hood
                                                                        (b)  Canopy hoods—catch
                                                                            contaminants that rise
                                                                            into them
                                                                  To fan
            Source: Cooper and Alley, 1990.
                                                                        (c)  Capturing hoods—reach
                                                                            out to draw in contaminants
Figure 7-5.  Three commonly used hood designs.
                                                                123

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                     Entry  •—



        Source: NIOSH, 1973.


 Figure 7-6, Components of a hood exhaust system.
                                        Hood
                         Cleaner
Table 7-39.  Advantages/Disadvantages of Hoods to Capture PM/VOC Emissions


	Advantages      	                          Disadvantages
90-100% PMA/OC capture efficiencies are possible

Much data available regarding selection and design of hoods
Conversion of an area source into a point source. Most air
pollution control equipment is designed for point sources
Emission source must be accessible to hood.

Contaminant diluted by air flow into hood. This can effect air pollution
control efficiencies (e.g., carbon adsorption, incineration).

Power cost may be high due to required capture velocity and headless
through ductwork. Use of hoods is practical for small area sources only.

Hoods subject to corrosion (e.g., acid gases, lime).
Tablo 7-40.  Parameters That Affect Hood Capture Efficiencies
                    Parameter
                                                                                         Comment
Distance between hood and farthest point of emitting source.


Volumetric flow rate into the hood


Surrounding air turbulence


Hood design
As this distance increases, for a given volumetric flow rate into the hood, the
capture efficiency decreases.

As the volumetric flow rate into the hood increases, the capture efficiency
increases.

As the surrounding air turbulence increases, the required volumetric flow
rate into the hood increases to maintain a given capture efficiency.

Hood designs are tailored to specific types of emitting sources. For
example, canopy hoods are designed to collect emissions from heated
open-top tanks.
                                                               124

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Table 7-41.   Range of Capture Velocities
   Condition of dispersion of contaminant
Examples Capture velocity (fpm)
Released with practically no velocity into quiet air

Released at low velocity into moderately still air


Active generation into zone of rapid air motion   ,
Released at high initial velocity into zone of
   very rapid air motion.	
Evaporation from tanks; degreasing, etc.

Spray booths; intermittent container filling;
low speed conveyor transfers; welding;
plating; pickling.

Spray painting in shallow booths; barrel
filling; conveyor loading; crushers.

Grinding; abrasive blasting.
 50-100

 100-200



 200-500


500-2000
Note:   In each category above, a range of capture velocity Is shown. The proper choice of value depends on several factors:
          Lower end of range
1.  Room air currents minimal or favorable to capture
2.  Contaminants of low toxlcity or of nuisance value only.
3.  Intermittent, low production.
4.  Large hood, large air mass in motion.
          Upper end of range
1. Disturbing room air current.
2. Contaminants of high toxicity.
3. High production, heavy use.
4. Small hood—local control only.
                                                                      125

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 Table 7-42.   Hood Design Equations
                                              Description
                                                  Slot
                                              Flanged slot
                                             Plain opening
                                           Flanged opening
                                                Booth
                                                                          Aspect ratio (W/L)
                                                                                     0.2 or less
                                                                              0.2 or less
                                                                       0.2 or greater and round
                                                                       0.2 or greater and round
                                                                                    To suit work
                                                                                                                           Air volume
                                                                                                                           Q = 3.7 LVX
                                                                                                                          Q = 2.8 LVX
                                                                                                                            V(10X2
                                                                                                                      Q = 0.75V (10X2 +A)
                                                                                                                         Q = VA = VWH
                                               Canopy
                                                                            To suit work
                                                                                                                         Q = 1.4PVD
Kay.
W
Conledine distance to point x in emissions plume (ft)
Length (It)
Width (II)
Height (ft)
Distance between hood and source (ft)
Area (sq. It.)
Ftowrate (It * /min)
Perimeter of hood (ft)
Velocity at point x (ll/min)
Source: NIOSH, 1973.
                                                                   126

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Table 7-43.  Hood Exhaust System Cost Estimate
Equipment item
Applicable dimensions
Cost ($)
Canopy hood       3/16 in. thick carbon steel       $2,400
                 10 ft. diameter.

Ductwork          100 ft. of 1 -foot                1,300
                 diameter, 16-gauge carbon
                 steel straight duct.

                 Four 1-foot diameter 16         1,750
                 gauge carbon steel 90°
                 elbows.

Radial tip fan       Moves 11,000 acfm at 10        7,700
                 in. H2O with a 45 1/2 in.
                 wheel diameter.

                               Total cost:    $13,150
7.10   References
  ACGIH. Industrial ventilation, 16th Edition American Confer-
      ence of Government Industrial Hygienists, Lansing, MI,
      1980.

  Aim, R.R., K.A. Olson, and R.C. Peterson. Using Foam to
      Maintain Air Quality During Remediation of Hazardous
      Waste Sites. Presented at the 80th Annual AWMA Meet-
      ing (Paper 87-18.3), New York City, June 21-26,1987.

.  Aul, Ed (Ed Aul Engineering). Personal communication from
      Ed Aul to Barry Walker of Radian Corporation. 1992.

  Buonicore, A.J. and W.T. Davis, ed., Air Pollution Engineer-
      ing Manual, Air and Waste Management Assoc.;  Van
      Nostrand Reinhold. NY, NY. 1992.

  Cooper, C.D. and F.C. Alley. Air Pollution Control A Design
      Approach. Waveland Press Inc. (ISBN 0-88133-521-5).
      Prospect Heights, IL. 1990.

  Landreth, R.E. et al., Lining of Waste Containment and Other
      Impoundment Facilities. U.S. EPA 600/2-88/052 (NTIS
      PB89-129670).

  Means Site Work Cost Data, K. Smit Sr. Editor. Published by
      RJ. Grant. 1991

  NIOSH.  The Industrial Environment - its Evaluation and
      Control. HSM-99-71-45. Washington, D.C. 1973.

  Radian Corp. Preliminary Assessment of Potential Organic
      Emissions from Dredging Operations. EPA Contract No.
      63-02-4288, WA 35. Report to Dennis Timberlake, U.S.
      EPA, Cincinnati, OH. September 1991.

   Radian Corp. GLOVES Software, Product Brochure. Radian,
      Austin, TX. 1992.

   Rusmar Corporation. Personal communication fromPaul Russo
      to Barry Walker of Radian Corporation. Rusmar, West
      Chester, PA. 1992.
Schmidt, C. (Independent Consultant). Personal communica-
    tion from Chuck Schmidt to Barry Walker of Radian
    Corporation. January 1992.

Springer, C., K.T. Valsaraj, and L.J.  Thibodeaux. In Situ
    Methods to Control Emissions from' Surface Impound-
    ments and Landfills. JAPCA Vol. 36, No. 12, pp!371-
    1374, December 1986.

Sprung Instant Structures Inc. Personal communication from
    Grant Cleverley to Barry Walker of Radian Corporation.
    Sprung, Allentown, PA. 1992.

3M Corporation. Personal Communication from Stu Wagner
    to Barry Walker of Radian Corporation. 3M, St. Paul, MN.
    1992.

U.S. EPA. Dust Control at Hazardous Waste Sites. EPA/540/
    2-85/003. U.S. EPA-HWERL, Cincinnati, OH. Novem-
    ber 1985a.

U.S. EPA. Compilation of Air Pollution Emission Factors, AP-
    42,4th Ed. U.S. EPA, Research Triangle Park, NC. 1985b.
    (Supplement A, October 1986; Supplement B, September
    1988; Supplement C, September 1990).

U.S. EPA. Handbook For Using Foams to Control Vapors
    From Hazardous Spills. EPA/600/8-86/019 (NTTS PB87-
    145660). U.S. EPA, Cincinnati, OH. July 1986a.

U.S. EPA. Field Evaluation of Windscreens as aFugitiveDust
    Control Measure for Material Storage Piles. EPA/600/7-
    86/027 (NTIS PB-86-231289). U.S. EPA, Research Tri-
    angle Park, NC. July 1986b.

U.S. EPA. Emission Control Technologies and Emission Fac-
    tors for Unpaved Road Fugitive Emissions. User's Guide
    EPA/625/5-87/022. U.S. EPA, Cincinnati, OH. Septem-
    ber 1987a.

U.S. EPA. Method for Estimating Fugitive Particulate Emis-
    sions from Hazardous Waste Sites. EPA/600/2-87/066
    (NTIS PB87-232203). U.S. EPA, Cincinnati.OH. August
    1987b.

U.S. EPA. Evaluation of the Effectiveness of Chemical Dust
    Suppressants on UnpavedRoads.EPA/600/2-87/112. U.S.
    EPA, Research Triangle Park, NC. 'November 1987c.

U.S. EPA. Control of Open Fugitive Dust Sources. EPA-450/
    3-88-008. U.S. EPA-OAQPS, Research Triangle Park,
    NC. September 1988a.

U.S. EPA. Dust and Vapor Suppression Technologies for Use
    During the Excavation of Contaminated Soils, Sludges, or
    Sediments. Land Disposal,  Remediation Action, Incin-
    eration, and Treatment of Hazardous Waste - Proceedings
    of the Fourteenth Annual Research Symposium (pp.53-
    64). EPA/600/9-88/021. U.S. EPA, Cincinnati, OH. July
     1988b.
                                                       127

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U.S. EPA. Engineering Bulletin - Control of Air Emissions
    from Material Handling. EPA/540/2-91/023. U.S. EPA,
    Cincinnati, OH. Octoljer 1991.

Vatavuk, W. Estimating Costs of Air Pollution Control. Lewis
    Publishers, Chelsea, MI. 1990.

Vogel, G.A. Air Emission Control at Hazardous Waste Man-
    agementFacilities. JAPCA Vol. 35, No. 5, p558-566, May
    1985.
                                                 128

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                                              Appendix A
                                   Remediation Control Vendors
The names of remediation control vendors that appear in this appendix were obtained from the March 1991 Journal of Air
and Waste Management Association Buyer's Guide, the Thomas Register, the Pollution Engineering Yellow Pages, and
various references in the literature.  Many of these vendors assisted in the preparation of this document by providing techni-
cal and costing information. These vendors are identified by an "*."

This list does not represent endorsement of any of the following companies by the U.S. EPA.  Furthermore, while the list is
as complete as possible, it does not necessarily include all vendors of all control devices that could be used at Superfund sites.
Carbon Adsorption
Amcec Corp., Solvent Recovery Div.*
Oakbrook, IL
(708)954-1515

American Environmental Int'l Inc.*
Northbrook, IL
(708)272-8635

Barnebey & Sutcliff Corp.*
Columbia, MD
(301)381-5870

Calgon Carbon Corp.*
Pittsburgh, PA
(412)787-6700

Cameron-Yakima*
Yakima, WA
(509)452-6609

DCI Corp.*
Indianapolis, IN
(317)872-6743

Dedert Corporation
Olympia Fields, IL
(708) 747-7000

Environmental Instruments, Inc.
Concord, CA
(800) 648-9355

Envirotrol, Inc.*
Sewickley, PA
 (412)741-2030
Extraction Systems, Inc.
Woonsocket, RI
(401)769-1113

RaySolv.lnc.
Piscataway, NJ
(908)981-0500

Vic Manufacturing Co.*
Minneapolis, MN
(612)781-6601

Zink Co., John*
Tulsa, OK
(918)747-1371
Catalytic Oxidation
Advanced Catalyst Systems Inc.*
South Plainfield, NJ
(908)753-9670

The Air Preheater Co. Inc.*
Wellsville, NY
(800)828-0444

Allied Signal*
Tulsa, OK
(708)450-3900

American Environmental International, Inc.
Northbrook, IL
(708) 272-8635
                                                     129

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 Anguil Environmental Systems*
 Milwaukee, WI
 (414)332-0230

 Branch Environmental Corp.*
 Somerville.NJ
 (908)526-1114

 CametCo.
 Hiram, OH
 (216)569-3245

 Dedcrt Corporation
 Olympia Fields, IL
 (708)747-7000

 EPCON Industrial Systems Inc.*
 The Woodlands, TX
 (409)273-1774

 Johnson Matthey*
 Wayne, PA
 (215)971-3000

 ORS Environmental Equipment*
 ChaddsFord.PA
 (215)558-1750

 Saxton Air Systems Inc.
 Harrisburg, PA
 (717)545-3784
 Condensers
 Airco Industrial Gases
 Murray Hill, NJ
 (908)464-8100

 Amcec Corp.*
 Oak Brook, IL
 (708)954-1515

 American Environmental Int'l, Inc.*
 Northbrook, IL
 (708)272-8635
Internal Combustion Engines
Remediation Services Int'l
Oxnard, CA
(805)644-5892

VR Systems Inc.
Anaheim, CA
(714)826-0483
 Environmental Techniques Inc.
 Huntington Beach, CA
 (714)962-5025
 SoilBeds/Biofilters
 Ambient Engineering Inc.
 Matawan, NJ
 (908) 566-7722
 Fabric Filters
 AirPol, Inc.
 Teterboro.NJ
 (201)288-7070

 American Air Filter
 Louisville, KY
 (502)637-0011

 Ducon Environmental Technology, Inc.
 Mineola, NY
 (516)420-4900

 Dustex Corp.
 Charlotte, NC
 (704)588-2030

 Fair Co.
 Los Angeles, CA
 (800)333-7320

 George A. Rolfes Co.*
 Boone, IA
 (515)432-3300

 Lodge-Cottrell Systems*
 Houston, TX
 (713)297-2092

 MIDWESCO Inc.*
 Winchester, VA
 (800)336-7300

 MiKroPul Environmental Systems*
 Morris Plains, NJ
 (201)606-5900

 Ogden Environmental Services, Inc*
 San Diego, CA
 (619)455-3045

P & S Filtration*
Skaneateles Falls, NY
(315)685-3466
                                                   130

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Sealed Air Technologies*
Fort Thomas, KY
(606)7881-4330

SteelcraftCorp.*
Memphis, TN
(901)452-5200

Wheelabrator Air Pollution Control
Pittsburgh, PA
(412)562-7300
Smidth, F.L. & Co.
Cresskill.NJ
(201)871-3300

United McGill
Columbus, OH
(614)443-0192

Wheelabrator Air Pollution Control
Pittsburgh, PA
(412)562-7300
Electrostatic Precipitators
American Air Filter
Louisville, KY
(502)637-0011

Beltran Associates Inc.
Brooklyn, NY
(718)338-3311

CE Environmental Systems Div.*
Birmingham, AL
(205)991-2832

Ducon Environmental Technology, Inc.
Mineola,NY
(516)420-4900

Flakt Inc. Environmental Systems Div.
Vancouver, BC
(615)693-7550

Fuller Co.
Bethlehem, PA
(215)264-6011

Lodge-Cottrell Systems*
Houston, TX
(713)297-2092

MiKroPul Environmental Systems*
Morris Plains, NJ
 (201)606-5900

 Niro Atomizer Inc.
 Columbia, MD
 (301)997-8700

 Sealed Air Technologies*
 Fort Thomas, KY
 (606)7881-4330
Scrubbers
Advanced Air Technology*
Arlington Heights, IL
(703) 394-9553

AirPol Inc.*
Teterboro, NJ
(201)288-7070

American Air Filter
Louisville, KY
(502)637-0011

Anderson 2000
Peachtree City, GA
(414)332-0230

Astec Industries*
Chattanooga, TN
(615)867-4210

B ACT Engineering, Inc.
Arlington Heights, IL
(708)577-0950

Bayco Industries of California*
San Leandro, CA
(415)562-6700

Branch Environmental Corp.*
Somerville, NJ
(908)526-1114

The Ceilicote Co.
Berea, OH
(216)243-0700

 Croll-Reynolds Co., Inc.
Westfield, NJ
 (908)232-4200
                                                     131

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 Dow Chemical Gas Spec Div.*
 Houston, TX
 (713)978-3894

 Ducon Environmental Technology, Inc.
 Mineola.NY
 (516)420-4900

 Environmental Elements Corp.*
 Baltimore, MD
 (301)368-7000

 Fisher-Klosterman*
 Louisville, KY
 (502)776-1505

 Lodge-Cottrell Systems*
 Houston, TX
 (713)297-2092

 MetPro Corp. Duall Div.*
 Owosso, MI
 (517)725-8184

 NaTec Environmental Systems Div.*
 Houston, TX
 (214)824-2910

 Niro Atomizer Inc.
 Columbia, MD
 (301)997-8700

 Ogden Environmental Services, Lie*
 San Diego, CA
 (619)455-3045

 Quad Environmental Technologies Corp.*
 Northbrook.IL
 (708)564-5070

 Wheelabrator Air Pollution Control
 Pittsburgh, PA
 (412)562-7300

 Zink Co., John*
 Tulsa.OK
 (918)747-1371
Thermal Oxidation
The Air Preheater Co. Inc.*
Wellsville,NY
(800)828-0444
 AmcecCorp.*
 Oakbrook, IL
 (708)954-1515

 American Environmental Int'l Inc.*
 Northbrook, IL
 (708)272-8635

 Astec Industries*
 Chattanooga, TN
 (615)867-4210

 Bayco Industries of California*
 San Leandro, CA
 (415)562-6700

 Branch Environmental Corp. PCT Div.*
 Somerville, NJ
 (908)526-1114

 Brule Incinerators*
 Blue Island, EL
 (708)388-7900

 CEL Incinerator System Inc.*
 Collegeville, PA
 (215)287-8037

 Conversion Technology, Inc.*
 Norcross, GA
 (404)263-6330

 DedertCorp.*
 Olympia Fields, IL
 (708)747-7000

 EPCON Industrial Systems Inc.*
 The Woodlands, TX
 (409)273-1774

 Eutherengy Systems, Inc.
 Sanford.MI
 (512)687-2899

 FECO Engineered Systems Inc., Environmental Div.*
 Cleveland, OH
 (216)441-2400

 In-Process Technology*
 Sunny vale, CA
 (408)745-1066

Johnson Matthey*
Wayne, PA
(215)971-3000
                                                   132

-------
M & S Engineering and Manufacturing Co. Inc.*
Broad Brook, CT
(203)627-9396

MetPro Corp. Duall Div.*
Owassa, MI
(517)725-8184

NAOInc.*
Philadelphia, PA
(215)743-5300

Precision Quincy Corp.
Woodstock, IL
(815)338-2675

REECOInc.*
Morris Plain, NJ
(201)538-8585

Salem Industries*
South Lyon, MI
(313)437-4188

Saxton Air Systems Inc.
Harrisburg, PA
(717)545-3784

Somerset Technologies Inc. Ross-Waldron Div.
New Brunswick, NJ
 (908)356-6000

 Smith Engineering Co.*
Duarte, CA
 (714)923-3331

 Surface Combustion
 Toledo, OH
 (800)537-8980

 Vulcan Iron Works Inc.*
 Wilkes-Barre.PA
 (717)822-2161

 WBR Engineering Inc.
 Cherry Hill, NJ
 (609)354-9372

 Williams Environmental*
 Stone Mountain, GA
 (800)247-4030
Zink Co., John*
Tulsa,OK
(918)747-1371

Venturi Scrubbers
Croll-Reynolds Co., Inc.
Westfield.NJ
(908)232-4200

Fairchildlnt'l
Glen Lyn, VA
(703)726-2380
Miscellaneous (HEPA Filters)

Covers/Barriers
see local contractors
 Foams
 3M: Industrial Chemicals Div.: Environmental Protection
 Group
 St. Paul, MN
 (612)733-3493

 Rusmar
 West Chester, PA
 (215)436-4314
 Water Sprays
 see local contractors
 Enclosures
 Sprung Instant Structures Inc.
 Allentown,PA
 (800)677-7864

 Houston, TX
 (713)520-6888

 see also local contractors
 Wind Barriers
 see local contractors
                                                     133

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             Region
                                              Appendix B
                              Regional Air/Superfund Coordinators
                                       (as of September 1992)
                                                  Name
I RoseToscano
H Alison Devine
HI Patricia Flores
IV Lee Page
V Charles Hall
VI MarkHansen
VII Wayne Kaiser
VIE NormHuey
K KathyDiehl
X Chris Hall
(617)565-3280
(212)264-9893
(215)597-9134
(404)347-2864
(312)886-6043
' (214)655-7223
(913)551-7603
(303)293-0969
(415)744-1133
(206)553-1949
 Bibliography of Air/Superfund Documents

 AS-1       Stoner, R., et al. Procedures for Conducting Air Pathway Analyses for Superfund Activities, Interim Final
            Document: Volume 1 -Application of Air Pathway Analyses for Superfund Activities. EPA-450/1-89-001
            (NTIS PB90-113374/AS). July 1989.

            Eklund, B., et al. Procedures for Conducting Air Pathway Analyses for Superfund Activities, Interim Final
            Document Volume 2 - Estimation of Baseline Air Emissions at Superfund Sites (Revised). EPA-450/1-89-
            002a (NTIS PB90-270588). August 1990.

            Eklund, B., el: al. Procedures for Conducting Air Pathway Analyses for Superfund Activities, Interim Final
            Document: Volume 3 - Estimation of Air Emissions From Clean-up Activities at Superfund Sites  EPA-450/1-
            89-003 (NTIS PB89-180061/AS). January 1989.

            Stoner, R., et al. Procedures for Conducting Air Pathway Analyses for Superfund Activities, Interim Final
            Document: Volume 4 - Procedures for Dispersion Modeling and Air Monitoring for Superfund Air Pathway
            Analyses. EPA-450/l-89-004(NTlSPB90-113382/AS). July 1989.

            TRC Environmental Consultants.  A Workbook of Screening Techniques For Assessing Impacts of Toxic Air
            Pollutants. EPA-450/4-88-009. September 1988.

            Salmons, C., F. Smith, and M. Messner.  Guidance on Applying the Data Quality Objectives For Ambient Air
           Monitoring Around Superfund Sites (Stages I & II). EPA-450/4-89-015 (NTIS PB90-204603/AS). August
            1989.
 AS-2
AS-3
AS-4
AS-5
AS-6
AS-7
           Pacific Environmental Services. Soil Vapor Extraction VOC Control Technology Assessment  EPA-450/4-89-
           017. September 1989.
                                                  134

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AS-8       TRC Environmental Consultants. Review and Evaluation of Area Source Dispersion Algorithms for Emission
           Sources at Superfund Sites. EPA-450/4-89-020. November 1989.

AS-9       Letkeman, J. Superfund Air Pathway Analysis Review Criteria Checklists. EPA-450/1-90-001 (NTIS PB90-
           1825447AS). January 1990.            •        ,   /,,

AS-10     Smith F  C Salmons/M. Ressner, and R. Shores. Guidance on Applying the Data Quality Objectives For
           Ambient Air Monitoring Around Superfund Sites (Stage ffl). EPA-450/4-90-005 (NTIS PB90-20461 I/AS).
           March 1990.

AS-11     Saunders, G. Comparisons of Air Stripper Simulations and Field Performance Data. EPA-450/1-90-002.
           .March 1990.

AS-12     Damle, A.S., and T.N. Rogers. Air/Superfund National Technical Guidance Study Series:  Air Stripper Design
           ', Manual. EPA-450/1-90-003. May 1990.

AS-13      Saunders, G. Development of Example Procedures for Evaluating the Air Impacts of Soil Excavation Associ-
            ated with Superfund Remedial Actions. EPA-450/4-90-014(NTISPB90-255662/AS). July 1990.

AS-14      Paul, R. Contingency Plans at Superfund Sites Using Air Monitoring. EPA-450/1-90-005 (NTIS PB91-
            ,10212,9). September 1990.

AS-15      Stroupe, K, S. Boone, and C. Thames. User's Guide to TSCREEN - A Model For Screening Toxic Air
            Pollutant Concentrations. EPA-450/4-90-013. December 1990.

 AS-16      Winges, K.D.  User's Guide for the Fugitive Dust Model (FDM) (Revised), User's Instructions. EPA-910/9-88-
            202R (NTIS PB90-215203.PB90-502410). January 1991.

 AS-17 '     Thompson, P., A.Ingles,and B.Eklund. Emission Factors For Superfund Remediation Technologies. EPA-
       '•'-:!"; 450/1-91-001 (NTIS PB91-190-975), March 1991.

 AS-18      Eklund, B., C. Petrinec, D. Ranum, and L. Howlett.  Database of Emission Rate Measurement Projects -Draft
           ;; Technical Note. EPA-450/1-91-003'(NTISPB91-222059). June 1991.

 AS-19      Eklund, B., S. Smith, and M. Hunt. Estimation of Air Impacts For Air Stripping of Contaminated Water.  EPA-
            450/1-91-002 (NTIS PB91-211888), May 1991 (Revised August 1991).

 AS-20     -Mann, G. and J: Carroll. Guideline For Predictive Baseline Emissions Estimation Procedures For Superfund
            Sites. 'EPA-450/1-92-002 (NTIS PB92-171909). January 1992.

 AS-21      Eklund, B., S. Smith, P. Thompson, and A. Malik. Estimation of Air Impacts For Soil Vapor Extraction (SVE)
       • •-•-•••: Systems. EPA-450/l-92-001.(NTISPB92-143676/AS), January 1992.  :

 AS-22      Carroll, J. Screening Procedures For Estimating the Air Impacts of Incineration at Superfund Sites. EPA-450/
           .  1-92-003 (NTIS PB92-171917). February 1992.

 AS-23      Eklund, B., S. Smith, and A. Hendler. Estimation of Air Impacts For the Excavation of Contaminated Soil.
      .    •  EPA 450/1-92-004 (NTIS PB92-171925), March 1992.

 AS-24      Draves, J. and B. Eklund.  Applicability of Open Path Monitors for Superfund Site Cleanup. EPA-45 l/R-92-
             001. May 1992.
                                                     135

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      vvEFA
                           United States
                           Environmental
                           Protection Agency
                                             Office of
                                             Air Quality Planning
                                             and Standards
September 1993
                           AIR/SUPERFUND  COORDINATION
                           PROGRAM
offices
                                     PURPOSE


              rPOSB °f thS Air/Superfund Coordination program is to assist EPA Regional Superfund


              Evaluate the impact of air emissions from Superfund sites prior to and during remediation
              3(10

              Develop and implement  site cleanup measures to mitigate these  impacts to  ensure
              protection of public health and the environment.
                             REGIONAL ACTIVITIES

       An Air/Superfund Coordinator in each Regional Air office is responsible for ensurina that air
 program  support Is provided to Superfund.  Air offices provide routine site support s "rtices such as

 S!±SE and T?6",? Pr°PO,SalS' Plans' and Studies'   TheV  ParticiP*e  in deoSrs relaS to
 preremedtel, remedial, and removal actions that may have significant air impacts. They help to ensure
 that Superfund site decisions involving air pollution issues are consistent with Federa  State and

 Sn1rHand-Pt° CieSrf,Th,ey alS° may Perf0rm Special field evaluations du™9 remova and
                                    — Jn ^ SUCh 3S ^ m0delin9' m



                      PROGRAM SUPPORT ACTIVITIES

       The program includes four types of activities to support the Regional Offices. They are:

       0      Coordination         o     Technical assistance

             Tracing             °     National Technical Guidance Studies

Coordination:

       Coordination program facilities the exchange of information on Air/Superfund issues

Sat^tS9 ufnalf ™T ^ betW6en Regi°ns and EPA He^q£^oSTa
updated technical information  and periodic reports to these offices on  ongoing  studies.  Coordination
                                       136

-------
meetings are  held at four month  intervals to exchange information, coordinate the overall program,
participate in miniworkshops, and receive briefings on pertinent technical and administrative subjects.

Training:

       Training involves briefing  Regional  Air  office staff on Superfund program  issues, priorities,
methods, and procedures; and briefing Regional Superfund staff and contractor personal on air issues,
and guidance  for analyzing and resolving them.

Technical Assistance:

       Technical assistance is offered to Regional  Air offices to assist them in analyzing air issues
associated with specific sites,  reviewing  analyses prepared  by Superfund contractors, and preparing
recommendations on remedial actions proposed to minimize air impacts.

National Technical Guidance Studies:

       National Technical Guidance Studies (NTGS) provide Regional Air and Superfund staffs and State
and local agency staffs with technical support, data, and guidance to improve the quality of the data base
and the analysis of air issues associates with Superfund sites.

/•*
o
o
0
o
o

1-


AIR/SUPERFUND COORDINATORS
Region 1
Region II
Region III
Region IV
Region V
Abdi Mohamoud
(617) 565-4044
Alison Devine
(212) 264-9868
Patricia Flores
(215)597-9134'
Lee Page
(404) 347-2864
Dan Meyer
(312) 886-9401
0 Region VI
0 Region VII
0 Region VIII
0 Region IX
0 Region X
Mark Hansen
(214) 655-6582
Wayne Kaiser
(913) 551-7603
Norm Huey
(303) 293-0969
Kathy Diehl
(415)744-1133
Chris Hall
(206)553-1949
    WHERE CAN I OBTAIN INFORMATION ON THE AIR/SUPERFUND
                                       PROGRAM

                           Regional Air/Superfund Coordinators
                                             or
                       Office of Air Quality Planning and Standards
                                      Joseph Padgett
                                       (919)541-5589
                                            137

-------
                                               Appendix C
                                              Bibliography
  VOC and PM Emission Controls
 Point Sources
 The Air Pollution Consultant. VOC Emission Control During Site Remediation. McCoy and Associates, Lakewood CO
   September/October 199 la.                                 .                                        '

 The Air Pollution Consultant. Biofiltration Shows Potential as 'an Air Pollution Control Technology. McCoy and Associates
   Lakewood, CO. November/December 1991b.

 Baker, R.W., K. Hibino, J. Mohr, and T. Kuroda. Membrane Research in Energy and Solvent Recovery from Industrial
   Effluent Streams. DOE/ID/12379-T2, report for the period 5/11/83 - 31/1/85. Prepared by Membrane Technology &
   Research, Inc. for the U.S. DOE. 1985.       •

 Baker, R.W., N. Yoshioka, J.M. Mohr, and A. J. Khan. Separation of Organic Vapors Air. J. Membrane Science, Vol. 31,
   pp25y-27 ] *  1987.

 Brkkwell, M., M. de Zeeuw, and F. Sapienze. Flue Gas Treatment Technologies in Western Europe: Regulations and
   Practice International Waste Management.  In: Proceedings of the 12th National Conference on Hazardous Materials
   Control/Superfund '91. HMCRI, Silver Spring, Maryland. 1991.           '  '

 Brna, T. G. and C.B. Sedman. Waste Incineration and Emission Control Technologies. EPA/600/D-87/147-S.  1987.

 Brna, T.G. Controlling PCDD/PCDF Emissions from Incinerators by Flue Gas Cleaning.  EPA/600/D-90/239.  1990.

 Brunner, C.R. Incineration Systems: Selection and Design. Van Nostrand Reinhold, New York.  1984.

 Buck, F.A. and D.E. Hasselmann. Control of Air Emissions From Soil Venting Systems.  Presented at the Symposium on
   New Technologies for Waste Incineration (Paper No. 94a). Aprils, 1989.

 Byers, W.D. Control of Emissions From an Air Stripper Treating Contaminated Groundwater. Environmental Progress Vol
   7, No. 1. February 1988.                                               .               ,              '

 Chu, RJ. VOC Emission Control Technologies for Site Remediation. In: Proceedings of National Research & Development
   Conference on the Control of Hazardous Materials, Anaheim, CA. HMCRI Publications Dept., Greenbelt, MD. 1991.

 Cooper, C. and F. Alley. Air Pollution Control - A Design Approach. Waveland Press, Prospect Heights, IL. 1986.

Danielson,J.A.,ed. Air Pollution Engineering Manual-Second Edition.  (AP-40) U.S. EPA. RTP, NC. May 1973.

Donnelly, J.R. and K.S. Felvang.  Low Outlet Temperature Operation Resource Recovery SDA Emission Control Systems
  In: Proceedings of the 82nd Annual Meeting and Exhibition of A WMA. Anaheim, CA.  June 1989.

Donnelly, J.  Air Pollution Controls for Hazardous Waste Incinerators. Thermal Treatment and Air Pollution Control In-
  Proceedings of the 12th National Conference onHazardous Materials Control/Superfund'91. December 1991.
                                                   138

-------
Frame, G.B. Air Pollution Control System for Municipal Solid Waste Incinerators. JAPCA, Vol. 38, No. 8. 1988.

HWC. Internal Combustion Engines Destroy Vapors From Gasoline Cleanup Projects. The Haz. Waste Consultant, ppl .4-
  1.7. McCoy and Associates, Lakewood, CO.  Sept/Oct 1988.

Hesketh, H.E. Air Pollution Control: Traditional and Hazardous Pollutants. Technomic Publishing Co., Lancaster, PA.
  1991.

Hummel, K.E. and T.P. Nelson. Test and Evaluation of a Polymer Membrane Preconcentrator. Prepared by Radian Corp.
  EPA 600/2-90-016. April 1990.

Katari, V.W., W. Vatavuk, and A.H. Wehe.  Incineration Techniques for Control of Volatile Organic Compound Emissions,
  Part I: Fundamentals and Process Design Considerations. JAPCA, Vol. 37, No. 1. 1987a.

Katari, V.W., W. Vatavuk, and A.H. Wehe.  Incineration Techniques for Control of Volatile. Organic Compound Emissions,
  Part'll: Capital and Annual Operating Costs.  JAPCA Vol. 37, No. 2.  1987b.

Keener, T.C. and D, Zhou. Prediction of Activated Carbon Adsorption Performance Under High Relative Humidity Condi-
  tions. Env. Progress, Vol. 9, No. 1, pp40-46. February 1990.

Kittrell, J., C. Quinlan, and J. Eldridge. Direct Catalytic Oxidation of Halogenated Hydrocarbons. JAWMA, Vol. 41, No. 8,
  ppll29-'ll33. 1991.                                            •

Kosusko, M., M.E. Muffins, K. Ramanathan, and T.N. Rogers. Catalytic Oxidation of Groundwater Stripping Emissions.
  Env. Progress, Vol. 7, No. 2, pp!36-142,May; 1988.

 Kosusko, M. and C.M. Nunez. Destruction of Volatile Organic Compounds Using Catalytic Oxidation.  JAPCA, Vol. 40,
  No. 2, pp254-259, February 1990.                      '

 Kosusko, M. and G.M. Ramsey. Destruction of Air Emissions Using Catalytic Oxidation. EPA/600/D-88/017. (NTIS
   PB88-214952). May 1988.

 Larsen, E.S. and M J. Pilat. Design and Testing of a Moving Bed VOC Adsorption System. Env. Progress, Vol.  10, No. 1,
   pp75-82, February 1991.

 Lawless, P.A. and L.E. Sparks. A Review of Mathematical Models for ESPs and Comparison of their Successes. In:
   Proceedings of the Second International Conf. on Electrostatic Precipitation, pp513-522. S. Masuda, ed., Kyoto. 1984.

 Leson, G.  and A. Winer. Biofiltration: An Innovative Air Pollution Control Technology for VOC Emissions. JAWMA, Vol.
   41, No.  8. August 1991.

 Marzone,  R.R. and D.W. Oakes. Profitably Recycling Solvents from Process Systems. Pollution Eng., Vol. 5, No. 10, pp23-
   24.  1973.

 Miller, D. and L. Canter. Control of Aromatic Waste Air Streams by Soil Bipreactors. Env. Progress, Vol. 10, No. 4, ppSOO-
   306. November 1991.

 Nothrup Services Inc. Fabric Filter Workshop Reference Materials. Air Pollution Training Institute. RTP,NC.  1977.
 Oglesby, S. and G.B. Nichols. A Manual of Electrostatic Precipitator Technology. Prepared by the Southern Research
   Institute for the National Air Pollution Control Admin. APTD-0610 (NTIS PB-196380).  1970.

 Pan, C.Y. and H.W. Habgood. An Analysis of the Single Stage Gaseous Permeation Process.. Ind. Eng. Chem. Fundam., Vol.
    13,pp323-331.  1974.

  Pederson, T. and J. Curtis. Soil Vapor Extraction. Technology: Reference Handbook. EPA/540/2-91/003 (NTIS PB91 -
    168476). 1991.
                                                      139

-------
                                           Separatl°n °f °rganic Vap°rs from Ain AICHE SymP- Ser- Vol. 82, No.




  Purus.Inc. On-Site Organic Contaminant Destruction with Advanced Ultraviolet Flashlamps. 1991.



  Roy K.A  Hazmat World, Vol. 3, No. 5. From a series on UV-oxidation technologies. Tower-Bonier Publishing, Glen
    miyn, UL. lyyo.
  Singh, S.P. and R.M. Counce. Removal of Volatile Organic Compounds From Groundwater: A Survey of Technologies

    Oak Ridge National Laboratory. (NTIS DE89-015653). May 1989.




  S^SS ™™ ve"i *?n M ^r1^ D^eelo?ment of a Synthetic Membrane for Gas and Vapor Separation. Pure and
    Applied Chem., Vol. 60, No. 12. Blackwell Scientific Publications, Ltd. Oxford, England.  1986.



  U.S.EPA. Air Stripping of Contaminated Sources: Air Emissions and Controls. EPA/540/3-87/017. 1987.



  U.S.EPA. Soil Vapor Extraction VOC Control Technology Assessment. EPA 450/4-89-017 (NTIS PB90-216995) Re
    search Triangle Park, NC. 1989.                     ,                                       -^o^;. K.B



  U.S. EPA. OAQPS Control Cost Manual - 4th Edition. EPA 450/3-90-006. January 1990.



  U.S.EPA Handbook: Control Technologies for Hazardous Air Pollutants.  EPA/625/6-91/014. Cincinnati, OH. June 1991.
    nnnvM              **?*' ^^ ""* COn^1 Efflciendes °f Thermal and Catalytic Incineration for the
   Control of Volatile Organic Compounds. JAWMA, Vol. 41 , No. 4. Pittsburgh, PA.  1 991a.
    nnrnvnr   ™               W<*e> ^ COSt Estimation of T**** ™« Catalytic Incinerators for the
   Control of VOCs. JA^VMA, Vol. 41 , No. 4, pp497-501 . 1 99 1 b.



 Vatavuk, W. Estimating Costs 'of Air Pollution Control. Lewis Publishers. Chelsea, MI. 1 990.



 Vatavuk, W. and R. Neverfl. Estimating Costs of Air Pollution Control Systems, Part XI: Estimate the Size and Cost of

   Baghouses. Chem. Eng.,ppl53-158. March 22, 1982.



 Walas, S.M. Chemical Process Equipment Selection and Design.  Butterworth Publishers, Boston, MA. 1988.



        Vtv ^f Cnt °f Contaminated Water' Air> ^d Soil with UV Flashlamps. Env. Progress, Vol. 1 0, No. 4.  New
         \« 1991.
 Area Sources


 A1^'R^:A; ??!!,' "S* f • Pe^^^Sing Foam t0 Maintain Air Quality DurinS ^mediation of Hazardous Waste
  Sites. Presented at the 80th Annual AWMA Meeting (Paper 87-18.3), New York City, June 21-26, 1987.



 Cooper, CD. and F.C. Alley. Air Pollution Control: A Design Approach. Waveland Press. Prospect Heights, IL.  1990.



 C°A ' CAi' ASAatSn a"d C°ntro1 °f Air Contaminants Du™g Hazardous Waste Site Remediation. Presented at the 80th
  Annual AWMA Meeting (Paper 87-18.1), New York City, June 21-26, 1987.



 NIOSH. The Industrial Environment - its Evaluation and Control. HSM-99-71-45. Washington, DC.  1973.



Radian Corp. Air Quality Engineering Manual for Hazardous Waste Site Mitigation Activities - Revision #2. NJ Depart-

  ment of Environmental Protection. May 1989.
           > Preli™na? Assessment of Potential Organic Emissions from Dredging Operations. EPA Contract No.63-02-

  4288. Report to Dennis Timberlake, U.S. EPA, Cincinnati, OH. September 1991 .
                                                   140

-------
Schmidt, C.E. and R. Stephens. Case Study: Control and Monitoring of Air Contaminants During Site Mitigation. Presented
  at the 80th Annual AWMA Meeting (Paper 87-18.2), New York City, June 21-26,1987.

Shen, T.T., T.P. Nelson, and C.E. Schmidt. Assessment and Control of VOC Emissions from Waste Disposal Facilities. In:
  Air Pollution Engineering Manual - Buonicore and Dvis Eds. AWMA, Pittsburg, PA.  1992.

Shen, T.T. and G.H. Sewell. Control of VOC Emissions From Waste Management Facilities. J. Env. Eng., Vol. 114, No. 6,
  pp!392-1400. 1988.

Springer, C., K.T. Valsaraj, and L J. Thibodeaux, In-Situ Methods to Control Emissions from Surface Impoundments and
  Landfills/U.S. EPA Project Summary EPA/600/S2-85/124. July 1986.

Springer, C., K.T. Valsaraj, and L.J. Thibodeaux. In-Situ Methods to Control Emissions from Surface Impoundments and
  Landfills.'JAPCA Vol. 36,No. 12,ppl371-1374. December 1986.

Todd, Q.R., W. Beers, W. Celenza, and P. Puglionesi. Dust and Vapor Suppression Technologies for Use During the
  Excavation of Contaminated Soils, Sludges, or Sediments. In: Proceedings of the 14th Annual Hazardous Waste Research
  Symposium. EPA/600/9-88/021, pp53-64. July 1988.               .                                 •

U.S. EPA. Dust Control at Hazardous Waste Sites. EPA/540/2-85/003. November 1985,

U.S. EPA. Handbook For Using Foams to Control Vapors From Hazardous Spills. EPA/600/8-86/019 (NTIS PB87-
  145660). July 1986.        "                                       .

U.S. EPA. Field Evaluation of Windscreens as a Fugitive Dust Control Measure for Material Storage Piles. EPA/600/7-86/
  027. July 1986.

U.S. EPA. User's Guide - Emission Control Technologies and Emission Factors for Unpaved Road Fugitive Emissions.
  EPA/625/5-87/022. September 1987.

U.S. EPA.  Method for Estimating Fugitive Paniculate Emissions from Hazardous Waste Sites. EPA/600/2-87/066 (NTIS
  PB87-232203). Cincinnati, OH. August 1987.                                 .            . .   .

 U.S. EPA.  Evaluation of the Effectiveness of Chemical Dust Suppressants on Unpaved Roads. EPA/600/2-87/112. Re-
   search Triangle Park, NC. November 1987.    ,                        '    ,'  ,

 U.S. EPA.  Control of Open Fugitive Dust Sources. EPA-450/3-88-008. U.S. EPA-OAQPS, Research Triangle Park, NC.
   September 1988.

 U.S. EPA.  Land Disposal, Remediation Action, Incineration, and Treatment of Hazardous Waste - Proceedings of the
   Fourteenth Annual Research Symposium. EPA/600/9-88/021. July 1988.

 U.S. EPA.  Hazardous Waste TSDF - Fugitive Paniculate Matter Air Emissions Guidance Document. EPA 450/3-89-019
   (NTIS PB90-103250). Research Triangle Park, NC. May 1989.

 U.S. EPA. Engineering Bulletin - Control of Air Emissions from Material Handling. February 1991.

 Vatavuk.W. Estimating Costs of Air Pollution Control Equipment. Lewis Publishers, Chelsea, MI. 1990.

 Vogel, G.A. Air Emission Control at Hazardous Waste Management Facilities. JAPCA Vol. 35, No. 5, pp558-566. May
   1985.

 Wetherold, R.G., B.M. Eklund, and T.P. Nelson.  A Case Study of Direct Control of Emissions from a Surface Impoundment.
   Presented at the 11 th Annual EPA Symposium on Land Disposal, Remedial Action, Incineration and Treatment of Hazard-
   ous Waste.  EPA/600/9-85/013. April 1985.    ..'.-"
                                                     141

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  Overviews of Soil Cleanup Techniques
    lnTl           ' T' DUlan%'n ^ A- IngliS' ^ Emissions From the Treatment of Soil Contaminated with Petro-
    leum Fuels and Other iSubstances. EPA-600/R-92-124. July 1992.


                                   ' EmiS$i°n FaCt°r$ ** Superftlnd Remediation Technologies. EPA-450/ 1-9 1-001.


  U.S.EPA. Underground Storage Tank Corrective Action Technologies. EPA/625/6-87-015. January 1987.

  U.S EPA. Air/Superfund National Technical Guidance Study Series, Volume III: Estimation of Air Emissions from
    Cleanup Activities at Superfund Sites. EPA-450/1-89-003. (NTISPB89- 18006 I/AS). January 1989.

  U.S.EPA. Handbook on In-Situ Treatment of Hazardous Waste-Contaminated Soils. EPA/540-2-90/002. January 1990.

  U.S.EPA. Summary of Treatment Technology Effectiveness for Contaminated Soil. EPA/540/2-89/053. June 1990.


  Cost of Remediation
        h      f t> r ' ST' and A' P^™- Costs of Remedial Acti<™ at Uncontrolled Hazardous Waste Sites: Worker
   Health and Safety Considerations. U.S. EPA Project Summary EPA/600/S2-86/037. September 1 986.

 Smit, Sr., K., Ed. Means Site Work Cost Data. R.J. Grant. 1 991 .

 U.S.EPA.  Remedial Action Costing Procedures Manual. EPA/600/S8-87/049. 1987.

 U.S.EPA.  Compendium of Costs of Remedial Technologies at Hazardous Waste Sites. EPA/600/S2-87/089. 1987.

 U.S. EPA.  OAQPS Control Cost Manual (Fourth Edition). EPA 450/3-90-006 (NTIS PB90-169954). January 1990.

 U.S.EPA.  Handbook: Control Technologies for Hazardous Air Pollutants. EPA/625/6-91/014. Cincinnati, OH.  June 1991.

 Vatavuk, W.M., Estimating Costs of Air Pollution Control. Lewis Publishers. Chelsea, MI. 1 990


 Selected Key References for Various Remediation Technologies

 Excavation
                        ' Hendlen Estimation of Air Impacts For the Excavation of Contaminated Soil. EPA 450/1-92-
Eklund B., D. Ranum, and A. Hendler. Field Measurements of VOC Emissions from Soils Handling Operations at Super-
  fund Sites. EPA Contract No. 68-02-4392, WA64. Report to James Durham, U.S. EPA, Research Trfangle Park NC
  oeptember 14, 1990.


Thermal Desorption
Troxlcr, W.L., J.J. Cudahy, R.P. Zink, and S.I. Rosenthal. Thermal Desorption Guidance Document for Treating Petroleum
  Contaminated Soils. EPA ContractNo. 68-C9-0033.  Report to James Yezzi, U.S. EPA, Edison, NJ. January 1992.

de Percin PR. Thermal Desorption Attainable Remediation Levels. In: Proceedings of the 17th Annual Hazardous Waste
  Research Symposium. EPA/600/9-91/002, pp51 1-520. April. 1991.
                                                   142

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U.S. EPA. Engineering Bulletin- Low-Temperature Thermal Desorption Treatment. EPA/540/0-00/000. December 1990.

Incineration
Oppelt, E.T. Incineration of Hazardous Waste - A Critical Review. JAPCA, Vol. 37, No. 5, pp558-586. May 1987.

U.S. EPA. Engineering Bulletin - Mobile/Transportable Incineration Treatment. EPA/540/2-90/014. September 1990.

IT Corp.  Screening Procedures For Estimating the Air Impacts of Incineration at Superfurid Sites: EPA-450/1 -92-003 (NTIS
  PB92-171917). February 1992.

U.S. EPA. Guidance on Metals and Hydrogen Chloride Controls for Hazardous Waste Incinerators. Vol. IV of the Hazard-
  ous Waste Incineration Guidance Series. August 1989.

Brna, T.G. and C.B. Sedman. Waste Incineration and Emission Control Technologies. EPA/600/D-87/147. May 1987.
                      ••'•',     '(''•"'•.
U.S..EPA. Performance Evaluation of Full-Scale Hazardous Waste Incineration. Five Volumes, (NTIS PB85-129500).
  November 1984.

Soil Vapor Extraction
U1S. EPA. Handbook of Soil Vapor Extraction (SVE). EPA/540/2-91/003. 1991.

Hutzler, N.J., B.E. Murphy, and John S. Gierke. State of Technology Review ~ Soil Vapor Extraction Systems. EPA-600/2-
  89/024 (NTIS PB89-195184). June 1989.

Johnson, P.C., M.W. Kemblowski, J.D. Colthart, D.L. Byers, and C.C. Stanley. 'A Practical Approach to the Design, Opera-
  tion, and Monitoring of In-Situ Soil-Venting Systems. Ground Water Monitoring Review, Spring 1990.

U.S. EPA. Demonstration Bulletin for In-Situ Steam/Hot-Air Soil Stripping. EPA/540/M5-90/003. February 1990.

Biodegradation
U.S. EPA. Engineering Bulletin-Sluny Biodegradation.  EPA/540/2-90/016.  September 1990.

Nelson, M.J., J.V. Kinsella, and T. Montoya. In-Situ Biodegradation of TCE-Contaminated Groundwater. Env. Progress,
   Vol. 9, No. 3, pp!90-196. August 1990.


Air Stripping
Vancit, M.A., et al. Air Stripping of Contaminated Water Sources - Air Emissions and Controls. EPA-450/3-87-017 (NTIS
   PB88-106166). August 1987.

 U.S. EPA. Air/Superfund National Technical Guidance Study Series:  Air Stripper Design Manual. EPA-450/1-90-003.
   May 1990.

 U.S. EPA. Air/Superfund National Technical Guidance Study Series:  Comparisons of Air Stripper Simulations and Field
   Data.  EPA-450/1-90-002. March 1990.              ,

 U.S. EPA. Selection Guide For Volatilization Technologies for Water Treatment.  EPA/600/2-88/014 (NTIS PB88-165683).
   January 1988.

 U.S. EPA. Performance of Air Stripping and GAG for SOC and VOC Removal From Groundwater. EPA/600/14 (NTIS
   PB89 110274). September 1988.        .
                                                     143

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 McKinnon, RJ. and J.E. Dyksen. Removing Organics From Groundwater Through Aeration Plus GAC J of AWWA
  pp42-47. May 1984.


 Stabilization/SolidiGcation
 Ponder, T.C. and D. Schmitt. Field Assessment of Air Emissions From Hazardous Waste Stabilization Operations. In-
  Proceedings of the 17th Annual Hazardous Waste Research Symposium. EPA/600/9-91/002. April. 1991.


 U.S. EPA. Handbook for Stabilization/Solidification of Hazardous Wastes. EPA-540/2-86/001. U.S. EPA, Cincinnati, OH.
  June 1986.


 Wcitzman, L., L. Hamel, P. dePercin, B. Blaney. Volatile Emissions from Stabilized Waste. In: Proceedings of the Fifteenth
  Annual Research Symposium. EPA-600/9-90/006. February 1990.

 Solvent Extraction/Soil Washing
Hall, D.W., J.A. Sandrin, and R.E. McBride. An Overview of Solvent Extraction Treatment Technologies. Env Progress
  Vol. 9, No. 2, pp98-105.  May 1990.                                                              '   •      '


U.S.EPA. Engineering Bulletin - Soil Washing Treatment.  EPA/540/2-90/017. September 1990.

Miscellaneous

U.S.EPA. AP-42: Compilation of Air Pollutant Emission Factors, Fourth Edition.  U.S. EPA, Office of Air Quality Plan-
  ning and Standards, Research Triangle Park, NC. September 1985.
                                                   144

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                                           Appendix D
                 Categorization of Commonly Encountered Compounds
Class of Compounds
Example Compounds
Aromatic Hydrocarbons
Aliphatic Hydrocarbons
Halogenated Hydrocarbons
Ketones/Aldehydes
 Other Oxygenated Hydrocarbons
 Inorganic Gases
    Benzene
    Toluene
    Xylenes
    Ethylbenzene

    Hexane
    Heptane

    Methylene chloride
    Chloroform
    Carbon tetrachloride
    1,1 -dichloroethane
    Trichloroethylene
    1,1,1 -trichloroethane
    Tetrachloroethylene
    Chlorobenzene

    Acetone
    Methyl ethyl ketone
    Methyl isobutyl ketone
    Cyclohexanone
    Formaldehyde
    Acetaldehyde

    Methanol
    Ethylene glycol
    Cellulose
    Ethers
    Phenols
    Epoxides

    Hydrogen sulfide
    Hydrogen chloride
    Sulfur dioxide
    Nitrogen oxide
    Nitrogen dioxide
                                                 145

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 Class of Compounds
Example Compounds
 Metals
 Polynuclear Aromatics
 Pesticides/Herbicides
 Miscellaneous
    Mercury
    Lead
    Chromium
    Arsenic
    Cadmium
    Zinc
    Beryllium
    Copper

    Polychlorinated biphenyls (PCBs)
    Benzo(a)pyrene
    Naphthalene
    Anthracene
    Chrysene

    Chlordane
    Lindane
    Parathion

    Asbestos
    Cyanides
    Radionuclides
                     Potential Air Contaminants by Generic Type of Contaminant

 Volatiles (>1 mm Mercury vapor pressure at 25°C)
    •   AH monochlorinated solvents; also trichloroethylene, trichloroethane, tetrachloroethane.
    •   Most simple aromatic solvents: e.g., benzene, xylene, toluene, and ethylbenzene.
    •   Most alkanes up to decane (C10).
    •   Inorganic gases: e.g., hydrogen sulfide, chlorine, and sulfur dioxide.

Semi-Vofatiles (l-10'7mm Mercury vapor pressure at25°C)
    •   Most polychlorinated biphenyls, dichlorobenzenes, aniline, nitroaniline, and phthalates.
    •   Most pesticides: e.g., dieldrin, toxaphene, and parathion.
    •   Most complex alkanes: dodecane and octadecane.
    •   Most polynuclear aromatic's: e.g., naphthalene, phenanthrene, and benz(a)anthracene.
    •   Mercury

Non-Volatttes or Particulate Matter (<10'7 mm Mercury vapor pressure at25°C)
    •   Larger polynuclear aromatics: e.g., chrysene.
    •   Metals: e.g., lead and chromium.
    •   Other inorganics: e.g., asbestos, arsenic, and cyanides.

                                        4U.S. GOVERNMENT PRINTING OFFICE: 1993 -yso-ooa' 60188   •
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