1

MEMORANDUM

To : Amy Hambrick, U.S. EPA, Sector Policies and Program s Division/Natural

Resources and Commerce Group

From : Eastern Research Group, Inc.

Date: January 2011

Subject: Revised Analysis of Beyond the Maximum Achievable Cont rol Technology

(MACT) Floor Controls for Existing SSI Units

1.0 INTRODUCTION

The U.S. Environmental Protection Agency (EPA), under section 129 of the Clean Air Act (CAA), is required to regulate emissions of nine poll utants from existing sewage sludge incineration (SSI) units. The nine pollutants are: hydr ogen chloride (HCl), carbon monoxide (CO), lead (Pb), cadmium (Cd), mercury (Hg), particulate ma tter (PM), total mass basis dioxins/furans (TMB PCDD/PCDF) and toxic equivalency ba sis dioxin/furans (TEQ PCDD/PCDF), nitrogen oxides (NO

x ), and sulfur dioxide (SO 2 ). The CAA requires EPA to determine the maximum achievable control technology (M ACT) for each subcategory of sources.

To do so, EPA must first determine the minimum stringenc y “floor” requirements. A previous memorandum documents the MACT floor analysis for SSI units. 1

EPA must also examine more stringent “beyond-the-floor ” (BTF) controls to determine MACT. Unlike the minimum stringency requirements of the floor, EPA must consider various impacts of the more stringent regulatory options such as costs and emissions reductions in determining whether MACT standards are to reflect BTF r equirements. This memorandum
describes the cost and emissions reductions for existin g SSI units achieved by applying BTF
controls.

Tables 1-1A and 1-1B summarize the costs and emissions reduc tion calculated for the MACT floor level of control and each of the analyzed BTF controls. Table 1-1A shows the cost
and ‘actual’ emission reductions of the MACT floor and t he BTF options, and Table 1-1B shows the cost and ‘potential’ emission reductions of the MAC T floor and the BTF options applied only to larger entities. As described in further detail in th e baseline emissions memo 2 , ‘actual’ emissions are based on calculations using actual sludge feed rates, wh ereas ‘potential’ emissions are based on calculations using sludge capacities.2Table 1-1. Summary of Cost and Emissions Reductions (tpy) for BTF Controls AnalyzedA.Costs and Emission Reductions Based on ‘Actual’ Sludge UsageControlsAnalyzedTCI ($)TAC ($/yr)Baseline Emissions and Incremental Emission Reductions (tons/year)CdCOHClPbHgNOxPMSO2PCDD/PCDF(mass)PCDD/PCDF(TEQ)BaselineEmissions- -0.9096 8501 28.15 2.3717 0.8942 2380 332.85 702.4 0.000006 0.00000041 - MACT Floor $55,047,913 $17,766,866 0.50 0 18.521.21 0.0022 6.8 58.1 431.5 0 02 - MACT Floor +AB for MH units $155,314,172 $46,097,268 0.499 686518.52 1.21 0.002 6.783 58.1 431.5 0 03 - MACT Floor +AB and ACI/FFfor MH units $486,470,566 $138,260,525 0.870 6865 18.52 2.28 0.667 6.783 299.9 431.5 0.00000495 0.000000332B.Costs and Emission Reductions Based on ‘Potential’ Sludge CapacityControlsAnalyzedTCI ($)TAC ($/yr)Baseline Emissions and Incremental Emission Reductions (tons/year)CdCOHClPbHgNOxPMSO2PCDD/PCDF(mass)PCDD/P CDF(TEQ)BaselineEmissions- -1.15 11576 43.34 3.0744 1.2099 3277 444.79 1077.5 0.000009 0.00000061 - MACT Floor$55,047,913 $17,766,866 0.60 0 29.94 1.50 0.0025 15.7 70 697.8 0 02 - MACT Floor +AB for MH units $155,314,172 $46,097,268 0.60 935429.94 1.50 0.00 15.72 69.57 698 0 03 - MACT Floor +AB and ACI/FFfor MH units $486,470,566 $138,260,525 1.098 9354 29.94 2.94 0.891 15.72 395.7 697.8 0.00000662 0.0000004443

The tables show three control scenarios analyzed for SSI units:

• Combination 1 is the MACT floor level of control for the two subcategories developed for existing multiple hearth (MH) units and fluidized bed (F B) units.

• Combination 2 is the MACT Floor level of control, with the addition of afterburner
retrofits for additional CO emissions reduction from MH units not already having an
afterburner.

• Combination 3 is the MACT Floor level of control, af terburner retrofits for MH units not already having them, and the addition of activated c arbon injection (ACI) in
combination with a fabric filter for MH units for addi tional Hg and PCDD/PCDF
emissions reduction.

Section 2.0 discusses the selection of more stringent co ntrols or emissions levels than the floor level reviewed for this analysis. Section 3.0 discusses the methodology used to estimate costs and emissions reductions of the more stringent controls an d Section 4.0 summarizes the controls selected for the BTF analysis.

2.0 SELECTION OF MORE STRINGENT CONTROLS

The MACT floor analysis for existing sources results i n emissions levels that each existing SSI unit is required to meet. The costs and emissions re duction of the MACT floor requirements were estimated using the following assumptions: (1) units that needed to meet the MACT floor for Cd, Pb, and PM would add a venturi scrubber (if they did not have one at proposal) or wet electrostatic precipitator (WESP), (2) units that needed to meet the MACT floor for HCl, and
SO 2 would add a packed bed scrubber (PBS), and (3) units that neede d to meet the MACT floor
for NO

x would add selective non-catalytic reduction (SNCR). All FB and MH units were determined to meet the floor level of control for Hg, PCDD/PCDF, and CO, and no additional control was necessary.

The control technologies that were costed to achieve the MACT floor levels for PM, Cd, Pb, HCl, SO 2 , and NO

x are the most effective controls available for SSIs to reduce these pollutants, given the high moisture content of SSI flue gas streams. The control effectiveness of the control devices used in the MACT floor analyses ar e discussed in the MACT floor cost and
emission reductions memorandum. 3 Since not every SSI unit was determined to need WESP, PBS, or SNCR to achieve the MACT floor level of con trol or operated them currently (i.e., the baseline level of control), these controls were ana lyzed for the entire SSI source category, which would require all units that did not have these controls a t baseline or for meeting the MACT
floors to add these controls.

For other combustion sources, carbon injection in com bination with a FF has proven to be highly effective in removing Hg. However, for high mois ture flue gas streams, such as emitted from SSI units, the use of FFs is problematic due to pluggin g/fouling. In order to use carbon injection with a FF with high moisture streams, a was te heat boiler, RTO, or afterburner is4

necessary to maintain a high enough temperature to keep th e stream above the dew point prior to sending the stream to the FF. This control combinatio n was costed as the beyond-the-floor control for Hg. Additional equipment may also be necessar y to reduce the temperature of the flue gas to prevent damage to the fabric filter bags. Sufficie nt information was not collected to estimate this cost; for this cost scenario, costs w ill be underestimated. Data gathered by EPA indicates that ACI applied to combustion sources with part iculate control can achieve 85-95 percent reduction of Hg, depending on the type of particulate control, with higher reductions achieved by units with fabric filters and lower reductio ns achieved by units with electrostatic precipitators. Based on efficiencies demonstrated in oth er source categories and in EPA studies, a beyond-the-floor reduction of 90 percent for Hg was used for carbon injection in combination with FF applied to existing MH unit controls. Previous EP A studies also show that PCDD/PCDF can be reduced by as much as 98 percent using ACI and FF toget her.

For CO, the MACT floor level of control for existin g MH units is 3,800 ppmvd, corrected to 7 percent oxygen. An add-on combustion device, such as a n afterburner or thermal oxidizer was analyzed as a more stringent control device that c ould be applied to SSI units. CO emissions data were collected from nine MH SSI units as part of t he data collection efforts supporting the development of emissions standards for SSI units. Table 2-1 summarizes the average CO
concentration levels from these units. 4 The table is grouped into three classes of SSI’s: (1) un its that do not use any combustion controls, (2) units that use an on-hearth afterburner, and (3) units
that use either a detached afterburner or thermal oxidiz er, or use FGR in combination with an onhearth afterburner.

Table 2-1. Summary of Average CO Emissions Collected From MH Un its

Classes Facility Location Unit ID Average CO emission level (ppmvd @ 7% O 2 ) Uncontrolled Boat Harbor VA 1 3,761

On-hearth afterburner Seneca MN 1 1,323
2 853

Central Contra Costa CA 1 905
2 752 Detached afterburner, thermal oxidizer, or
on-hearth afterburner with flue gas
recirculation Columbia Metro SC 1 63

Mountainview NJ 2 39

Upper Blackstone MA 1 28
3 59

On-hearth afterburners are the top hearth of a MH unit that has been re-designed so that sludge is rerouted to the second hearth. Retrofitting the MH unit with an on-hearth afterburner may require modifications to downstream air pollution con trol systems due to higher temperatures and larger volumes of exhaust gases. 5 While there will be reductions in CO and total hydroca rbon (THC) emissions, the reductions may be limited due to lo w temperature and limited residence time of the gas in the afterburner stage. The use of FG R in combination with an on-hearth afterburner shows significantly lower emissions level s than just using an on-hearth afterburner. However, this may be a generalization because only on e data point for this control combination5

was reviewed. Additionally, performance of FGR is often influenced by site specific parameters which may not be generalized to the entire subcategory.

Table 2-1 shows that MH units using an add-on afterburner o r thermal oxidizer can achieve CO emission levels less than 100 ppmv. The Clean Water Act (CWA) "503 Rule" [40 CFR Part 503] limits sewage sludge incinerators to 100 ppm THC as propane, dry basis, corrected to 7% oxygen, averaged for 30 days. The CWA 503 Rule allows substitution of 100 ppm CO dry basis, corrected to 7% oxygen for the THC ori ginally required. The 100 ppm
CO level was selected because this level was determine d to be a level that would be indicative of the THC concentration below 100 ppm. This allows the use of a lower cost, easier to maintain CO monitor in place of the difficult to keep online THC monitor. To be consistent with the CWA 503 regulations for disposal of sewage sludge for the beyond-th e-floor calculation, a value of 100 ppmv was used as the emission level that a MH unit with an afterburner could achieve. Beyond-the-floor controls were also evaluated for exis ting FB units. The proposed SSI MACT floor CO level for existing FB units (56 ppmvd, corrected t o 7 percent oxygen) is well below the 100 ppmvd emission level of the CWA 503 rule. The application o f an afterburner was determined not to achieve appreciable CO reduction form the proposed limit for the cost incurred. Therefore, no beyond-the-floor CO limit was considered for the FB subcategory.

3.0 METHODOLOGY USED TO ESTIMATE COST AND EMISSIONS
REDUCTIONS

The methodology used to calculate costs and emissions reduc tions from applying the more stringent controls followed the procedures discussed in the SSI Cost memorandum. 3 As described above, if a unit already had an afterburner, ACI, PBS, FF, or WESP, or needed one of these to meet the MACT floor limits, no additional costs were calculated for the beyond-the-floor analysis. Otherwise, these controls were costed out for the unit as appropriate. The algorithms, inputs for algorithms, and testing, monitoring, recordkeeping, and repor ting costs calculations are the same
as conducted for the MACT floor and are discussed in detail in the MACT floor cost and emissions reductions memorandum. However, ACI/FF combin ation was not required for units to meet the MACT floor, so the ACI and FF cost algorithm s are included with this memo, as Attachments A and B. Attachment C presents the inputs us ed for these algorithms.

Emissions reductions from application of the beyond-the- floor controls relative to the MACT floor limits were calculated using the following pro cedure. First, the reduction efficiency of the beyond-the-floor control for each pollutant was applied to the uncontrolled concentration
to determine the total reduction the control would achie ve. The reduction from uncontrolled levels to the MACT floor limits was previously calcula ted for the MACT floor cost and emissions reduction analysis. 3 For each pollutant, the incremental reduction between the more stringent beyond-the-floor control and the MACT floor was calcul ated by subtracting the MACT floor emissions reductions from the reductions achieved by the more stringent control.

4.0 SELECTION OF REGULATORY OPTIONS

Tables 4-1 and 4-2 summarize the costs, emissions reduction s, and incremental cost effectiveness of the controls analyzed in the BTF an alysis, for the case where ‘actual’ emission6

reductions are considered (Table 4-1) and the case where ‘ potential’ emission reductions are considered (Table 4-2). Further description of ‘actual’ emi ssions (based on actual sludge feed rates) and ‘potential’ emissions (based on unit sludge capa cities) can be found in the baseline
emissions memo. 2 The tables indicate that except for the afterburner, all of the controls applied result in a high incremental cost-effectiveness. Cons equently, these controls, with the exception of activation carbon injection in combination with a F F for Hg control at MH units, were considered infeasible. Mercury is a high priority pollutant of inte rest, and additional control beyond the floor for Hg was analyzed for the proposed rule. Three differen t control combinations were therefore selected for the beyond-the-floor analysis: (1) MACT F loor control only, (2) MACT Floor
control with the addition of afterburner retrofits for additional CO control for MH units not already having afterburners, and (3) MACT Floor control, afterburners for MH units not already having them, and ACI and FF for MH units for additional H g and PCDD/PCDF control. The costs, total emissions reductions, and incremental cos t effectiveness of the three control combinations are summarized in Table 4-3 (with ‘actual’ emissions) and Table 4-4 (with ‘potential’ emissions). Attachments D1 and D2 present th e costs for each control combination and subcategory for each SSI unit. Attachments E1 through E7 pr esent the emission reductions based on ‘actual’ sludge usage and supporting details for each beyond the floor control considered, and attachments F1-F7 present the emission reductions based o n ‘potential’ sludge capacity and supporting details for each beyond the floor control cons idered.

REFERENCES

1. Revised MACT Floor Analysis for the Sewage Sludge Incine rator Source Category. Memorandum from Eastern Research Group to Amy Hambrick, U.S. Environmental Protection Agency. January 2011.

2. “Revised Estimation of Baseline Emissions From Exist ing Sewage Sludge Incineration Units” Memorandum from Eastern Research Group, Inc. to Amy Hambrick, U.S. Environmental Protection Agency. January 2011.

3. Revised Cost and Emissions Reduction of Complying with th e MACT Floor for Existing SSI Units. Memorandum from Eastern Research Group to Am y Hambrick, U.S. Environmental Protection Agency. January 2011.

4. Facility, Unit, and Emissions Test Database for the Sewage Sludge Incineration Source Category. Memorandum from Eastern Research Group to Amy Hambrick, U.S. Environmental Protection Agency. June 2010.

5. A Comparison of Fluid Bed and Multiple Hearth Biosolids Inc ineration. Ky Dangtran, John Mullen, and Dale Mayrose. Paper presented at the 14 th Annual Residuals and Sludge Management Conference. February 27-March 1, 2000, Boston MA.7

TABLES AND ATTACHMENTS

Table 4: See BeyondTheFloorMemo_Table4.xlsx
4-1. Emissions Reductions and Costs by Control: ‘Actual’ Emission Reductions
4-2. Emissions Reductions and Costs by Control: ‘Potenti al’ Emission Reductions
4-3. Emissions Reductions and Costs by BTF Control Combi nation: ‘Actual’ Emission
Reductions
4-4. Emissions Reductions and Costs by BTF Control Combi nation: ‘Potential’ Emission
Reductions

Attachment A. Control Costs: Fabric Filter Algorithm for Incinerators See BeyondTheFloorMemo_AttachA-D.xlsx

Attachment B. Control Costs: ACI Cost Algorithm for Incinerators See BeyondTheFloorMemo_AttachA-D.xlsx

Attachment C. Inputs to BTF Analysis See BeyondTheFloorMemo_AttachA-D.xlsx

Attachment D. Cost Details See BeyondTheFloorMemo_AttachA-D.xlsx

D1. Fluidized Bed Sewage Sludge Incinerators
D2. Multiple Hearth Sewage Sludge Incinerators

Attachment E. Emission Reduction Details (‘Actual’) See BeyondTheFloorMemo_AttachE.xlsx

E1. Emission Reductions for Each BTF Control Conside red

E2. BTF Emissions for SNCR

E3. BTF Emissions for Afterburner Retrofit

E4. BTF Emissions for PBS

E5. BTF Emissions for WESP

E6. BTF Emissions for FF

E7. BTF Emissions for ACI/FF

Attachment F. Emission Reduction Details (‘Potential’ )8

See BeyondTheFloorMemo_AttachE.xlsx

F1. Emission Reductions for Each BTF Control Conside red

F2. BTF Emissions for SNCR

F3. BTF Emissions for Afterburner Retrofit

F4. BTF Emissions for PBS

F5. BTF Emissions for WESP

F6. BTF Emissions for FF

F7. BTF Emissions for ACI/FF

Attachment G. Correspondence between EPA’s testing and monitoring group and ERG regarding Hg control.