1

MEMORANDUM 

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

Resources and Commerce Group 

From: Roy Oommen, ERG 

Date: June 2010 

Subject: Estimation of Impacts for New Units Constructed Within Five Years After 

Promulgation of the SSI NSPS 

1.0 INTRODUCTION 

The U.S. Environmental Protection Agency (EPA), under section 129 of the 

Clean Air Act (CAA), is required to develop new source performance standards (NSPS) 

regulating emissions of nine pollutants and opacity from sewage sludge incineration 

(SSI) units: hydrogen chloride (HCl), carbon monoxide (CO), lead (Pb), cadmium (Cd), 

mercury (Hg), particulate matter (PM), dioxins/furans (CDD/CDF), nitrogen oxides 

(NOx), and sulfur dioxide (SO2). This memorandum describes the estimation of cost and 

emission impacts of complying with the NSPS. Section 2.0 discusses the estimation of 

the number of new sources that may be constructed within five years after promulgation 

of the SSI NSPS. Section 3.0 discusses the methodology used to estimate cost and 

emissions reductions from complying with the maximum achievable control technology 

(MACT) floor level of control required in the NSPS, and Section 4.0 discusses control 

options more stringent than the MACT floor level of control. 

2.0 ESTIMATION OF NEW SOURCES 

 Several significant changes have occurred to SSI units in the past 20 years. The 

U.S. EPA’s Office of Water (OW) set emission and discharge standards for sewage 

sludge disposal methods (including incineration) in 1993 (40 CFR part 503). As a result 

of the 503 rule, many wastewater treatment facilities chose to use alternative methods for 

disposing of sewage sludge, such as landfilling or land application, rather than try to meet 

the incineration requirements. Many of the closed incinerators had been operated by 

municipalities or agencies serving smaller populations, i.e., less than 50,000 people.1

 

The general trend has also been for facilities still incinerating sewage sludge to 

replace older multiple hearth (MH) units with newer fluidized bed (FB) units because of 

better emissions performance, savings in fuel cost, and flexibility in operation. Since 

1988, there have been over 40 new FB systems installed, with 11 replacing existing MH 

units.2

 Discussions with the National Association of Clean Water Agencies (NACWA), 

the industry trade group, indicated that only FB units are likely to be constructed in the 
2

future.3 Consequently, it was assumed that any new units that would be built after 

promulgation of the NSPS would be a FB design. 

In order to estimate the number of new sources that may be constructed in the five 

years following promulgation of the NSPS, the number of sources being constructed five 

years prior to proposal of the rule was reviewed to determine if there was a trend. Under 

EPA's "New Source Review" (NSR) program, if a company is planning to build a new 

plant or modify an existing plant such that air pollution emissions will increase by a large 

amount, then the company must obtain an NSR permit. The NSR permit is a construction 

permit which requires the company to minimize air pollution emissions by changing the 

process to prevent air pollution and/or installing air pollution control equipment. The 

NSR program defines control levels based on the type of program the source is subject to: 

 reasonably available control technology (RACT), best available control technology 

(BACT), or lowest achievable emissions reduction (LAER). Information from the EPA’s 

RACT/BACT/LAER database contains case-specific information on the "Best Available" 

air pollution technologies that have been required to reduce the emission of air pollutants 

from stationary sources. This information has been provided by State and local permitting 

agencies. The database was searched for sewage sludge incineration units permitted or 

constructed since 2005. The search results showed two fluidized bed (FB) units at the 

R.L. Sutton Water Reclamation facility in Georgia were permitted in 2005 and completed 

construction in 2008 and are currently in operation.4

 Additional information collected 

from State environmental agencies and permits indicated an additional 3 units at the Mill 

Creek Wastewater Treatment Plant in Ohio were expected to finish construction and be in 

operation in 2010.5 All of these new FB units were replacements for MH units. 

Based on the data collected, and assuming the trend in construction continues, 

five additional FB units will be permitted to be constructed in five years after the NSPS is 

proposed. However, given the time necessary to review and assess the requirements of 

the NSPS and plan, permit, and construct incineration units, it is unlikely that all five 

would be in operation in the five years. For this analysis, it was assumed at least two 

new FB units would be constructed and in operation in this time period. 

3.0 METHODOLOGY USED TO ESTIMATE COST AND EMISSION 

REDUCTIONS OF THE MACT FLOOR LEVEL OF CONTROL. 

Cost and emission reductions for new units complying with the NSPS were 

calculated by: (1) determining the controls that these units would most likely apply if the 

NSPS were not in place (referred to as the baseline level of control), (2) calculating the 

cost of complying with the NSPS emission levels, and (3) estimating the emissions 

reduction from complying with the NSPS emissions levels. Each of these steps is 

discussed in more detail. 
3

3.1 Determining Baseline Controls 

The baseline level of control that new units would likely implement (in the 

absence of the NSPS) was determined from reviewing the most common controls used at 

existing FB units, as shown in the SSI inventory memorandum.1 Table 3-1 shows the 

distribution of controls. Based on this information, the baseline controls assumed for the 

new units are a combination of venturi scrubbers and impingement scrubbers. Data 

gathered on the controls currently used at FB units indicates that few FB units operate an 

afterburner, because their CO emissions are already low. However, in order to meet the 

new source floor limit, the analysis costs out an afterburner to reach the limit. In reality, 

new FB units that are constructed are likely to be designed to meet the CO level. Costing 

an afterburner provides a conservative estimate of costs. 

3.2 Calculating Baseline Emissions

The SSI baseline emissions memorandum6

 documents the calculation of baseline 

emissions from existing FB SSI units. Baseline emissions are calculated on a mass basis 

by multiplying the concentration of the pollutant in the emission stream, flow rate of the 

emission stream, and the hours of operation of the SSI unit. For units where no 

emissions test data were collected, baseline emissions were estimated using an average 

uncontrolled concentration and applying reduction efficiencies associated with the 

control devices located at each SSI unit for each pollutant. 

An average flue gas flow rate factor was also developed for FB units relating the 

flue gas flow rate to the dry sludge feed rate from units providing emission test data. For 

units where sludge feed rates were not collected, unit capacities were multiplied by a 

capacity utilization factor of 75 percent, which was the median of the capacity 

utilizations reported in the ICR survey responses. More information about how unit 

capacity values were obtained can be found in the SSI inventory database memorandum.1

The flow rate of the flue gas stream was calculated by multiplying the dry sludge feed 

rate by the average flue gas flow rate factor. 

Based on the information gathered from RACT/BACT/LAER and permits, it is 

likely that new FB units constructed will be replacements for existing units. However, it 

cannot be determined how many units will be replaced at a facility or the total number of 

units that will be in operation at a facility. For this analysis, the simplest and most 

conservative assumption was used, that only one FB unit would be constructed replacing 

one older MH unit. The operating hours for facilities operating one unit was assumed to 

be 8400 hours per year (incorporating two weeks downtime). 

Table 3-2 shows the average concentration factors, average dry sludge capacity, 

and operating hours, as well as other default parameters necessary for the costs. These 

factors were applied to each new unit estimated to be constructed within the next five 

years. Table 3-3 shows the estimated baseline concentrations for new units. 
4

3.3 Calculating Costs and Emission Reductions

Costs were calculated using the procedures and algorithms discussed in the 

memorandum, “Cost and Emissions Reduction of Complying with the MACT Floor for 

Existing SSI Units”.7 Control devices costed out were those that would be necessary to 

meet the MACT floor level of control for new sources. It is possible for some units with 

wet scrubbers to comply with the NSPS limits for SO2 by adding caustic. However, it is 

uncertain if all units could do this. Therefore, this analysis assumes a packed bed 

scrubber would be used, which would provide a more conservative estimate of costs. 

Similarly, wet electrostatic precipitators can be used for PM control; a FF was costed in 

this analysis to provide a conservative estimate of costs. Table 3-3 shows the comparison 

of baseline emissions levels to MACT floor levels to determine the amount of pollutant 

reduction needed and the types of control devices that would be used to meet the levels. 

Emission reductions from applying the MACT floor requirements to the baseline 

emission levels are presented in Table 3-3. The inputs to the cost algorithm are presented 

in Table 3-2. For this analysis, it was assumed that controls applicable for PM would 

also reduce PM2.5. 

Table 3-4 shows the estimated total capital investment (TCI) and total annual 

costs (TAC) calculated for a single unit using the cost algorithms previously discussed. 

The table also shows the monitoring, testing, reporting, and recordkeeping costs. The 

table shows the TCI and TAC for the two new FB units that are assumed to be 

constructed and in operation in the five years after proposal of the NSPS. Table 3-5 

shows the detailed capital and annual costs of continuous CO emissions monitoring for 

each new SSI unit (continuous CO emissions monitoring costs were not presented in the 

“Cost and Emissions Reduction of Complying with the MACT Floor for Existing SSI 

Units” memorandum because it was an alternative monitoring requirement and not 

required) . 

4.0 ANALYSIS OF BEYOND THE FLOOR OPTIONS 

The control technologies costed to achieve the MACT floor levels are generally 

the most effective controls available: fabric filters for PM, Cd, Pb; activated carbon 

injection for Hg and CDD/CDF; afterburners for CO; and packed bed scrubbers for HCl 

and SO2. In addition, incremental additions of activated carbon have not been proven to 

achieve further reductions above the projected flue gas concentration estimated to 

achieve the limits for new sources. Data gathered does not indicate that any FB units 

operate NOx controls, such as selective noncatalytic reduction, selection catalytic 

reduction, or flue gas recirculation because the NOx emissions are already low. 

Therefore, no beyond the floor options were analyzed for this analysis because we are not 

aware of any technologies or methods to achieve emission limits more stringent than the 

MACT floor limits for new units, which are based on the lowest emitting FB units. 
5

5.0 REFERENCES 

1. Inventory Database for the Sewage Sludge Incineration Source Category. 

Memorandum from Eastern Research Group to Amy Hambrick, U.S. 

Environmental Protection Agency. June 2010.2. A Comparison of Fluid Bed 

and Multiple Hearth Biosolids Incineration. Ky Dangtran, John Mullen, and Dale 

Mayrose. Paper presented at the 14th Annual Residuals and Sludge Management 

Conference. February 27-March 1, 2000, Boston MA. 

3. Meeting minutes from Sewage Sludge Incinerator Informational Meeting with the 

National Association of Clean Water Agencies (NACWA). Research Triangle 

Park, NC. August 25, 2009 

4. R.L. Sutton Water Reclamation Wastewater Treatment permit # 4953-067-0018-V01-1 RACT/BACT/LAER Clearinghouse. http://cfpub.epa.gov/rblc/

5. Mill Creek Wastewater Treatment Plant. Final permit to install. Permit 

Applicatoin #14-05837. 

6. Estimation of Baseline Emissions From Existing Sewage Sludge Incineration 

Units. Memorandum from Eastern Research Group to Amy Hambrick, U.S. 

Environmental Protection Agency. June 2010. 

7. Cost and Emissions Reduction of Complying with the MACT Floor for Existing 

SSI Units. Memorandum from Eastern Research Group to Amy Hambrick, U.S. 

Environmental Protection Agency. June 2010. 
Table 3-1. Control Device Distribution for Fluidized Bed Incinerators1

Existing Control Devices # units

% Control Abbreviations:

Abbreviation

abd - mc - vs - imp

2 3.64 abd

abd - vs - imp - hss - cs 1 1.82 aboabo - imp - wesp 1 1.82 ac inject.ac inject. - vs(ad) - wesp

3 5.45 ac polish.

ccpt 1 1.82 agrcs - vs - pbt

2 3.64 bag

unknown

4 7.27 ccpt

vs

5 9.09 cs

vs - cs 1 1.82 cs/tgvs - imp 25 45.45 fgrvs - imp - wesp

8 14.55 hjs

vs- imp - wesp - ac polish. 1 1.82 hssvs(ad) - wesp 1 1.82 impTotal 55 100.00 pbs

pbt

Venturi scrubber (vs, vs(ad)) 49 0.89 rto

Impingement scrubber (imp) 38 0.69 vs

Wet ESP (wesp) 14 0.25 vs(ad)

Cyclone separator (cs)

4 0.07 wesp

Activated carbon (ac inject or ac polish)

4 0.07 whs

Afterburner (abo or abd)

4 0.07 ws

Packed bed scrubber (ccpt, pbs, pbt)

2 0.04 mc

packed bed towerwet hydrosonic scrubbewet scrubber (undefinemulticloneregenative thermal oxidventuri scrubberventuri pak or ring jet scwet electro static preciphorizontal gas scrubberhydrosonic scrubberimpingement tray scrupacked bed scrubbercounter-current packed cyclone seperatortwin gas cyclonic scrubflue gas recirculation

1 Email from Robert Dominak, CoChair NACWA Biosolids Management Committee, to Amy Hambrick, U.S. EPA, on 8/5/2009: “SSI Inventory Updated InSSI_Inventory (RPD 8-5-09 ).xls

Distribution of Control Combinations

Distribution of Individual Controls

Co

detached afterburneron-hearth afterburneractivated carbon injectiactivated carbon polishacid gas removal systebaghouse
3-2. Cost and Emission Reduction Calcualtion Inputs

Parameter

Default (Average of known data for FB 

subcategory)

Capacity (dtph) 2.26

Capacity (dry lb/hr) 4516.36

Sludge Feed Rate (dry tons/hr) 1.69

Sludge Feed Rate (dry lb/hr) 3387.27

Operating Hours (hr/yr)1 8400

Stack Gas Flow Rate (dscfm) 9239.97

Stack Gas Temp (°F)2 

1050

ACI Adjustment Factor3 1.03

Sludge Heating Value (btu/lb)4 7740

NOX, lb/MMBtu 0.07

PM(gr/dscf) 0.0054

HCl (ppmvd) 0.124

1. Conservatively assumed new unit would operate 350 days per year (2 weeks downtime).

2. Assumed average gas temperature used for commercial and industrial solid waste incinerators (CISWI)

3. ACI algorithm is based on 90% Hg reduction efficiency and 98% CDD/CDF reduction efficiency. This

adjustment factor will be used to adjust total annual costs to the estimated reduction efficiency needed to meet the floor.

4. Converted to btu/lb from 18 MJ/kg dried, undigested sludge (http://www.aseanenvironment.info/Abstract/41015799.pdf)
Table 3-3. Summary of Emission Reductions for New SSI Units

Pollutant

Concentration Units

Additional Control Needed for MACT

Baseline Concentration NSPS Limit

MACT Emission Concentration

Emission Reduction (concentration)

Emission Reduction (tp

Cadmium (Cd) mg/dscm Add FF 0.002 0.00051 0.00051 0.002 2.36E-Carbon Monoxide (CO) ppmvd Add ABD 16.331 7.4 7.4 8.931 1.51E+Hydrogen Chloride (HCl) ppmvd none1 0.124 0.12 0.050 0.074 1.64E-

Lead (Pb) mg/dscm Add FF 0.011 0.00053 0.00053 0.011 1.53E-Mercury (Hg) mg/dscm Add ACI 0.014 0.001 0.001 0.013 1.82E-Nitrogen Oxides (NOx) ppmvd none2 27.926 26 26 1.926 5.35E-

Particulate Matter (filterable) mg/dscm Add FF 12.443 4.1 4.1 8.343 1.21E+Particulate Matter (PM2.5) mg/dscm Add FF 11.801 2.3 2.3 9.501 1.38E+Sulfur Dioxide (SO2) ppmvd Add PBS 3.303 2.0 2.0 1.303 5.04E-Total Dioxin/Furans ng/dscm Add ACI 15.962 0.024 0.024 15.938 2.32E-Total Dioxin/Furans (TEQ) ng/dscm Add ACI 1.312 0.0022 0.0022 1.310 1.90E-1. Assumed Scrubber (installed for SO2 control) has 98% efficiency for HCl control2. Assumed units could meet limit by making minor adjustments rather than installing add-on control3. The NSPS Dioxin/Furans limits determined for MH units were used rather than the limits determined for FB units because MH limits reflect better performancControl Device Key:

FF = fabric filterABD = detached afterburnerACI = activated carbon injectionPBS = packed bed scrubber
Table 3-4. MACT Costs Associated with Model FB Unit

TCI TAC

Add FF $1,995,892 $580,670Add PBS $1,013,167 $233,832Add ACI $25,786 $163,338Add ABD $625,106 $233,589

Subtotal: $3,659,952 $1,211,429

Initial Stack Test $61,000Annual Stack Test $61,000Bag Leak Detection System $25,500 $9,700Wet Scrubber Monitoring $24,300 $5,600ACI Monitoring $0 $9,800Annual Control Device Inspection $1,000CO CEMS $134,000 $41,400Annual Visual Emissions Test of Ash Handling $250 $740Reporting and Recordkeeping $2,989

Subtotal: $245,050 $132,229

TOTAL: $3,905,002 $1,343,657

Assuming 2 new units come online in 5 years:

Total TCI after 5 year: $7,810,003

5th Year TAC: $2,687,314

Control Device Key:

FF = fabric filterABD = detached afterburnerACI = activated carbon injectionPBS = packed bed scrubberControlsMonitoring, Testing, Reporting and RecordkeepingParameter
A. Parameters

1. Recording lime/carbon flow, min/4-hr period2. Annual operating hours, hr/yr (H)3. Cost index a. 2008 575.4

 b. 2006 499.6 c. 1997 386.5 d. 1993 359.2 e. 1992 358.24. Operating labor wage rate, $/hr (LR) $34.605. Capital recovery factor, 20-yr equipment life, 7% interest (CRF)

= [i x (1 + i)a] / [(1 + i)a - 1], where i = interest rate, a = 

equipment life

0.09439

B. Total Capital Investment, $ (TCI)

1. Planning $4,0002. Select type of equipment $10,0003. Provide support facilities $20,6004. Purchased equipment cost (PEC) $48,4005. Install and check equipment $18,2006. Perf. spec. tests (certif.) $15,7007. Prepare QA/QC plan $17,5008. Total capital cost = Planning + selecting equipment + support facilities + 

PEC + installation + perf. spec. tests + QA/QC plan

$134,000

C. Annual Costs, $/yr

1. Operating labor = (5 min to record lime/carbon flow/4-hr period) x (1 

hr/60 min) x H x LR

2. Maintenance materials = 0.02 x TCI3. Operation & maintenance = Day-to-day activities + annual RATA + CGA + annual 

QA + O&M review and update

$27,600

4. Recordkeeping and reporting = $1,000 x (525.4/386.5) $1,2005. Overhead = 0.6 x (labor + maintenance materials)6. Property taxes, insurance, and administration

= 0.04 x TCI

7. Capital recovery = CRF x TCI $12,6008. Total annual cost = Operating labor + maintenance materials + 

recordkeeping and reporting + overhead + property taxes, insurance, and administration + capital recovery

$41,400

Notes:

Sources:

Table 3-5. CO Continuous Emissions Monitoring Costs

1. Hospital/Medical/Infectious Waste Incinerators (HMIWI) [EPA-HQ-OAR-2006-0534] Testing and Monitoring Options and Costs Memo (IV-B-66).2. E-mail and attachment from Peter Westlin, EPA, to Mary Johnson, EPA. August 19, 2008. Monitoring Options for SNCR on Medical Waste Incinerators.3. E-mail from Dan Bivins, EPA, to Mary Johnson, EPA. September 27, 2006. Cost of CO CEMS.1. Monitoring costs have been rounded to the nearest $100 to be consistent with level of rounding in original costs.Parameters/Costs Equation CO CEMS4. E-mail from Dan Bivins, EPA, to Mary Johnson, EPA. July 28, 2006. Some Preliminary Thoughts on the HWI Monitoring.