1



### MEMORANDUM

TO: Amy Hambrick, U.S. EPA, Sector Policies and Programs D ivision/Natural

Resources and Commerce Group

FROM: Eastern Research Group, Inc.

DATE: January 2011

SUBJECT: Revised Secondary Impacts of Controls for the Sewage Sl udge Incineration Source Category

1.0 INTRODUCTION

This memorandum presents the secondary impacts associat ed with control devices used to comply with the proposed standards for existing and new sewage sludge incineration (SSI) units. Secondary impacts result from the consumption of fuel, water, and electricity and generation of solid wastes by control devices.

Section 2.0 presents the background for the proposed standards . Section 3.0 presents the secondary impact estimates associated with control devic es necessary for all SSI units comply with proposed standards. This memorandum focuses only on s econdary impacts associated with

control devices. Section 4.0 summarizes the estimated se condary impacts that would result from the compliance of new units expected to come online in t he next five years. Section 5.0 summarizes the emissions resulting from increased fuel and electricity requirements for different

controls.

2.0 BACKGROUND

The U.S. Environmental Protection Agency (EPA), under sect ion 129 of the Clean Air Act (CAA), is required to regulate emissions of 9 polluta nts from existing sewage sludge incineration (SSI) units. The 9 pollutants are: hydrogen chl oride (HCl), carbon monoxide (CO), lead (Pb), cadmium (Cd), mercury (Hg), particulate matte r (PM), total mass basis dioxins/furans (TMB PCDD/PCDF) and toxic equivalency basis 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 (MACT) for each category or subcategory of sources. The SSI source category comprises two subcategories: multiple hea rth incineration units (MH) and fluidized bed incineration units (FB). To determine the MACT for each subcategory, EPA must first determine the minimum stringency “floor” requirem ents. Development of the MACT floors for SSI units is described in a separate memorandum. 1 

### An analysis of beyond-the-floor controls
was also conducted, in which three different control co mbinations were evaluated:

• Combination 1 is the MACT floor level of control for t he two subcategories developed for existing multiple hearth (MH) units and fluid ized bed (FB) units.2



### • 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, after burner retrofits for MH units not already having them, and the addition of activated car bon injection (ACI) in

combination with a fabric filter for MH units for additi onal Hg and PCDD/PCDF

emissions reduction.

3.0 SECONDARY IMPACT ESTIMATES FOR EXISTING UNITS

For the control combinations listed above, facilities m ay need to install the following types of control devices on SSI units:

• Venturi scrubbers (VS) or wet electrostatic precipitator s (WESP) to reduce Cd, Pb, and PM emissions,

• Packed-bed scrubbers (PBS) to reduce HCl and SO 2 

### emissions,

• Selective non-catalytic reduction (SNCR) to reduce NO

x 

### emissions,

• ACI systems, in combination with a FF, to reduce PCDD/P CDF and Hg emissions,

and

• Afterburners (AB) to reduce CO and organic compound emissions

.

Electricity is required to operate the pumps and fans asso ciated with WESP, VS, PBS, FF, and SNCR systems. Also, water and subsequent wastew ater disposal are required to operate VS, WESP, and PBS systems. Fabric filter and ACI syst ems require a method to dispose of the dust produced from the systems. Additionally, ACI requires the use of activated carbon. Supplemental fuel (i.e., natural gas) is required to operat e afterburners for MH SSI units.

Table 3-1 shows, for each of the controls analyzed, the estimated secondary impacts for the FB and MH subcategories.

The algorithms used in the cost analysis provide annual cost estimates for electricity, water, carbon requirements, and supplemental fuel as item ized components of the annual costs

for the control device. 2,3 

### These cost elements for the control devices anticipat ed to be installed to comply with the standards were then summed to provide an e stimate of the overall costs of electricity, water, activated carbon, and supplemental f uel. To estimate the secondary impact components (e.g., electricity, water, dust), the itemiz ed annual cost of each component was divided by the unit price of the component used by the algorithm

.3 

### Table 3-1. Secondary Impacts for Controls Analyzed

Controls Analyzed Subcategory Controls Required

for Compliance Electricity

Required (MW

hr/yr) Water

Required (gal/yr) Activated

Carbon Required (ton/yr) Dust

Produced (ton/yr) Supplemental

Fuel (mmcf ft 3

natural gas/yr)

1 -

MACT

Floor FB units PBS, SNCR 505 32,035,300 - - -

MH units VS, WESP, PBS 4,915 202,325,500 - - -

Total VS, WESP, PBS,

SNCR 5,420 234,360,800 - - -

2

- MACT

Floor +

AB for

MH units FB PBS, SNCR 505 32,035,300 - - -

MH VS, WESP, PBS, AB 4,915 202,325,500 - - 1,013

Total VS, WESP, PBS,

SNCR, AB 5,420 234,360,800 - - 1,013

3

- MACT

Floor +

AB and

ACI/FF

for MH

units FB PBS, SNCR 505 32,035,300 - - -

MH VS, WESP, PBS,

AB, ACI/FF 43,185 202,325,500 4,370 4,890 1,013

Total VS, WESP, PBS,

SNCR, AB, ACI/FF 43,690 234,360,800 4,370 4,890 1,013



### 4.0 SECONDARY IMPACT ESTIMATES FOR NEW UNITS

As discussed in the new source analysis memorandum, EP A expects that two new FB units would come online in the next five years 4 

### . Estimations of the secondary impacts resulting from the pollution controls implemented for these units were calculated using the same methodology described for existing units in Section 3.0.

Table 4-1 shows the estimated values for secondary impacts for the two new FB units.

Table 4-1. Secondary Impacts: New Units

Subcategory Controls Required

for Compliance Electricity

Required (MW

hr/yr) Water

Required (gal/yr) Activated

Carbon Required (ton/yr) Dust

Produced (ton/yr) Supplemen tal

Fuel (mmcf natural gas/yr)

New Units PBS, ACI/FF, AB 597 17,172,000 67.0 67.9 16.7



### 5.0 SECONDARY AIR POLLUTANT IMPACTS

Emission factors from EPA’s Egrid 5 

### database were used to calculate emissions resulting from the electricity required for additional control de vices, and emission factors from EPA’s AP42 emission factor document 6 

### were used to calculate emissions resulting from the com bustion of

additional fuel for afterburners. Increased electrical use from the controls will require additional4



### fuel to be burned in power plants, resulting in emissions of CO 2 

### and criteria pollutants, such as

SO 2 

### , NO

x 

### , and CO. Emissions of these pollutants (caused by increas e in electricity) were estimated using EPA’s Egrid database. 5 

### The Egrid database summarizes emissions of criteria pollutants on a per electrical usage basis (lb emitted pe r MW-hr), on a national average or state average basis. For this analysis the national average w as used. Afterburners require supplemental fuel , such as natural gas, to operate. The afterburner a lgorithm indicates the amount of fuel needed by each unit. To estimate emissions from combustio n of natural gas, emission factors

from EPA’s AP-42 emission factor document were used. 6 

### Tables 5-1 summarizes the resulting

emissions of CO 2 

### , CO, NO

x 

### , and SO 2 

### from combustion of natural gas supplemental fuel and increase electricity usage for the three control combina tions analyzed for existing sources. Table 5-2 shows the results for new sources, and table 5-3 shows results for combined existing and new sources. Table 5-4 shows the Egrid and AP-42 emission factor s used for the calculations.

REFERENCES

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

2. Revised Cost and Emission Reduction of the MACT Floor L evel of Control. Memorandum from Eastern Research Group, Inc. to Amy Ham brick, U.S. Environmental Protection Agency. January 2011.

3. Revised Analysis of Beyond the Maximum Achievable Contro l Technology (MACT) Floor Controls for Existing SSI Units. Memorandum from Eastern Research Group, Inc. to Amy Hambrick, U.S. Environmental Protection Agency. Jan uary 2011.

4. Revised Estimation of Impacts for New Units Construct ed Within Five Years After Promulgation of the SSI NSPS. Memorandum from Eastern Research Group, Inc. to Amy Hambrick, U.S. Environmental Protection Agency. January 2011.

5. EPA eGRID database eGRID2007 Version 1.1. Year 2005 summary t ables located at www.epa.gov/cleanenergy/documents/egridzips/eGRID2007V1_1_year05_S ummaryTab les.pdf

6. U.S. Environmental Protection Agency, 1995. Compilation of Air Pollutant Emission Factors (AP-42), Fifth Edition, Volume 1: Stationary a nd Point Sources, Chapter 1:

External Combustion Sources.5Table 5-1.SecondaryAir PollutantImpacts:ExistingUnitsAll Units ComplyControlsAnalyzedElectricity Requirements and Emissions(tons/yr)*Supplemental Fuel Requirements and Emissions(tons/yr)*Total Secondary Emissions(tons/yr)MWhper yrCO2EmittedNOxEmittedSO2Emittedft3Natural Gasper yrCO2EmittedCOEmittedNOxEmittedCO2EmittedCOEmittedNOxEmittedSO2Emitted1 - MACT Floor 5420 3602 5.2 14.3 - - - - 3,602 - 5.2 14.32-MACT Floor+ AB for MHunits5420 3602 5.2 14.3 1,013,417,920 60,805 42.6 50.7 64,407 42.6 55.9 14.33-MACT Floor+ AB and ACI/FFfor MH units43689 29039 42.3 114.9 1,013,417,920 60,805 42.6 50.7 89,844 42.6 93.0 114.9*Emissions estimated based on emission factors listed inTable 5-4.Table 5-2. Secondary Air Pollutant Impacts: New Units afterFive Years (2 New Units)Electricity Requirements and Emissions(tons/yr)*Supplemental Fuel Requirements and Emissions(tons/yr)*Total Secondary Emissions (tons/yr)MWh per yrCO2EmittedNOxEmittedSO2Emittedft3Natural Gasper yrCO2EmittedCOEmittedNOxEmittedCO2EmittedCOEmittedNOxEmittedSO2Emitted597 397 0.58 1.57 16,659,400 1000 0.70 0.83 1,397 0.70 1.41 1.57*Emissions estimated based on emission factors listed inTable 5-4.Table 5-3. Secondary Air Pollutant Impacts: Combined Existing and New Units after 5 YearsControls AnalyzedTotal Secondary Emissions (tons/yr)CO2EmittedCOEmittedNOxEmittedSO2Emitted1 - MACT Floor1,397 0.7 6.6 15.92 - MACT Floor + AB for MH units65,804 43.3 57.3 15.93 - MACT Floor + AB and ACI/FF for MH units91,241 43.3 94.4 116.56Table 5-4. Emission FactorsPollutantElectricityaNatural Gasb(lb/MWh)(lb/106scf)(lb/ft3)(ton/ft3)CO21,329120,0000.120.00006CO-848E-054.2E-08NOX1.93661000.00015E-08SO25.2589---a. National emission factors from Egrid5for EGUs.b. Natural gas emission factors from AP-42