Potential Impacts of Complying with MACT Standards 

for Biosolids Incinerators by Adding 

Additional Air Pollution Control Devices 

 

Since the MACT Standards are normally based on the average emissions from the 

top operating 12 percentile of regulated units, a substantial number of multiple hearth 

incinerators and fluidized bed incinerators, by definition, will be required to add 

additional air pollution control devices in order to achieve compliance with the ten 

potential MACT Standards. 

For this analysis, the following was assumed: 

• Fifty (50) of the 63 existing fluidized bed incinerators and 125 of the 167 existing 

multiple hearth incinerators will require new air pollution control systems to 

comply with the potential MACT Standards. 

 However, not all of the incinerators will be able to comply with the potential 

MACT Standards by installing additional air pollution control devices. These 

incinerators will have to be shut down and in most cases the sewage sludge will 

be hauled to municipal solid waste landfills for disposal. 

• Each of the POTWs that practice incineration have enough room around their 

incinerator(s) to install the additional air pollution control devices that might be 

required to meet the potential MACT Standards. 

While this is the best case scenario, there will be POTWs, like the Northeast Ohio 

Regional Sewer District’s Easterly WWTP, where these is simply not enough 

room to install additional equipment. As a result, this incinerator will have to be 

removed from services. 

• There is a lack of operational and maintenance (O&M) cost data for the additional 

air pollution control devices. This is the reason why, in most cases, only capital 

cost are presented. The capital costs presented herein, are NACWA’s current 

best estimate, and therefore, may be subject to change at a later date. 

• Cadmium, lead and mercury emissions are a function of the concentration of these 

metals in the biosolids, which can vary greatly from POTW to POTW. As a 

result, the installation of additional air pollution control devices will not enable all 

sewage sludge incinerators to meet potential MACT Standards for the three 

metals. 

• Removal efficiencies will vary from POTW to POTW depending on the 

concentrations of the regulated pollutants in the sludge fee and incinerator exhaust 

gases. 
It should also be noted that oxides of nitrogen and carbon monoxide emissions 

from sewage sludge incinerators are inversely proportional. As a result, there will be 

a substantial number of sewage sludge incinerators that will not be able to 

simultaneously comply with the two potential MACT Standards. 

 The following is a summary of the potential cost impacts of adding additional air 

pollution control devices on both fluidized bed incinerators and multiple hearth 

incinerators: 

1. Reduction in Particulate Matter and Metal Emissions 

It should be noted that there is not any data on the emissions of particulate matter 

less than 2.5 microns in diameter (PM2.5) and condensable particulate matter emissions 

from sewage sludge incinerators. As a result, it is not known what the MACT Standards 

will be and/or whether the two following air pollution control devices will be able to 

reduce condensable and PM2.5 emissions to enable POTWs to comply with the potential 

MACT Standards. 

• Advanced Scrubbing Systems

In order to reduce particulate matter and some of the particulate based cadmium, 

lead, and mercury, an advanced scrubbing system might be required. 

Recent bids for the Northeast Ohio Regional Sewer District Southerly WWTC’s 

new fluidized bed incineration project, the procurement cost of each of the new 

“Venturi Pak” advanced scrubbing system is $0.75 million. Assuming $0.5 - 1.0 

million for delivery and installation costs, related instrumentation, controls and 

electrical modifications, and engineering related services, the total cost of a single 

unit installed would be in the range of $1.25 - $1.75 million/unit. 

Total costs to replace existing venturi/impingement tray scrubbing systems with 

one of the two advanced scrubbing systems (i.e., “Venturi Pak” or “Ring Jet”) 

could be in the range of: 

 

$60 million - $90 million for fluidized bed incinerators 

$155 million - $220 million for multiple hearth incinerators 

• Wet Electrostatic Precipitators (ESPs) 

If wet electrostatic precipitators (ESPs) are required to reduce particulate matter 

and some of the particulate based metal emissions, costs would be substantially 

higher than the aforementioned costs for advanced scrubbing systems. 
In 2001, bids for a new biosolids handling complex at the Metropolitan WWTP in 

St. Paul, Minnesota which included the installation of three wet ESPs. The bid 

price for the three units was $2.49 million or $831,000 per unit. Associated 

design, ductwork, piping, structural, instrumentation and controls, electrical, etc, 

total $2.6 million. As a result, total costs averaged $1.7 million per wet ESP. 

Given substantial increases in corrosion resistant metal costs since 2001, along 

with a 44% increase in the Engineering News Record’s construction cost index, 

costs in 2009$ would be at least $2.5 million per wet ESP. 

 

 Assuming installed costs of $2.5 - $3.0 million per wet ESP, total costs 

 nationwide would be in the range of: 

 $125 million - $150 million for fluidized bed incinerators 

 $310 million - $375 million for multiple hearth incinerators 

 For the Northeast Ohio Regional Sewer District Southerly WWTC new fluidized 

 bed incineration project, approximately 15 feet would have to be added onto the 

 new facility to house the wet ESPs and associated equipment. The estimated cost 

 to add three wet ESPs to this project is $10 million, with estimated annual 

 additional electrical costs of $250,000. 

 The addition of the three wet ESPs would reduce Southerly’s projected 

 particulate matter emissions from 6 tons/year to 3 tons/year (i.e., 50%), with a 

 cost effectiveness of $250,000/ton of particulate matter removed (2013$). 

2. Reduction in Sulfur Dioxide and Oxide of Nitrogen Emissions 

• Sodium Hydroxide 

 To reduce sulfur dioxide and oxides of nitrogen emissions, sodium hydroxide 

could be added to the wet scrubbing systems. Costs to design, procure and install 

a sodium hydroxide addition system at the Southerly WWTC were estimated to be 

$0.5 million for three incinerators, with estimated annual chemical costs of $0.7 

 million/year. 

Assuming capital costs of $0.25 - $ 0.3 million per incinerator, the total capital 

costs nationwide would be in range of: 

$12.5 million - $15 million for fluidized bed incinerators 

$31 million - $38 million for multiple hearth incinerators 

The addition of a sodium hydroxide would reduce Southerly’s sulfur dioxide 
emissions from 6 tons/year to 3 tons/year (i.e., 50%), and the oxides of nitrogen 

emissions from 44 tons/year to 40 tons/year (i.e., 10%). This will result in a cost 

 effectiveness of $120,000/ton of sulfur dioxide removed and $90,000/ton of 

 oxides of nitrogen removed (2013$). 

• Urea or Ammonia

To reduce oxides of nitrogen emissions, either urea or ammonia would be added 

to the hot gases leaving the incinerators. Cost to design, procure and install a urea 

injection system at the Northeast Ohio Regional Sewer District Southerly WWTC 

has been estimated to be $ 5 million, with annual operating & maintenance costs 

of $0.5 million (2013$). 

Assuming capital costs of $ 1.5 - $ 2 million per incinerator, the total capital 

costs nationwide would be in range of: 

$75 million - $100 million for fluidized bed incinerators 

$185 million - $250 million for multiple hearth incinerators 

The addition of urea would reduce Southerly’s oxides of nitrogen emissions from 

6 tons/year to 3 tons/year (i.e., 50%), and the oxides of nitrogen emissions from 

44 tons/year to 32 - 40 tons/year (i.e., 10 – 25%). This would result in a life cycle 

cost effectiveness of greater than $60,000/ton of oxides of nitrogen removed 

(2013$). 

The procurement of an ammonia injection system at the Metropolitan WWTP in 

St. Paul, Minnesota in 2001 had a bid price approximately $400,000/incinerator 

(2009$). However, the unit is not being used due to the low oxides of nitrogen 

emissions from the plant’s three fluidized bed incinerators. 

It should also be noted that the use of urea and ammonia results in the conversion 

of the oxides of nitrogen to nitrous oxide (N2O) a greenhouse gas. 

3. Reduction in Mercury Emissions 

• Activated Carbon Adsorbing System

In 2005, the Ypsilanti, Michigan WWTP installed a new fluidized bed incinerator 

equipped with a proprietary activated carbon adsorbing system to reduce mercury 

emissions. Ypsilanti’s Consultant believes that this unit will also reduce dioxin 

emissions. The cost to procure and install the system is roughly $3 million. In 

addition, the activated carbon will have to be replaced once every three years. 
Assuming capital costs of $3.5 - $4 million per incinerator, total cost nationwide 

would be in the range of: 

$175 million - $200 million for fluidized bed incinerators 

$ 438 million - $500 million for multiple hearth incinerators 

• Activated Carbon Injection System followed by a Baghouse 

In 2001, bids were received for an activated carbon injection system/baghouse 

for each of the three new fluidized bed incinerators located at the Metropolitan 

WWTP in St. Paul, Minnesota. The bid price for the three systems, including 

procurement, installation, appurtenances and engineering related services, was 

$6 million or $2 million per unit. 

Given substantial increases in corrosion resistant metal costs since 2001 and a 

44% increase in the Engineering News Record’s construction cost index, costs in 

2009$ would be approximately $3 million per system. 

Assuming capital costs of $3.5 - $4.0 million per system, total costs 

nationwide would be in the range of: 

$175 million - $200 million for fluidized bed incinerators 

$438 million - $500 million for multiple hearth incinerators 

4. Reduction in Carbon Monoxide Emissions 

Carbon monoxide emissions can be reduced by utilizing either internal or external 

afterburners. However, this action, which requires the burning of substantial quantities of 

fossil fuel, will result in a substantial increase in oxides of nitrogen emissions and 

greenhouse gas emissions. 

While the use of internal afterburners will result in reduced carbon monoxide 

emissions, most if not all of the POTWs that practice incineration will be required to 

install external afterburners to meet the potential MACT Standards. 

It has been estimated that the cost to procure and install an afterburning system, 

along with all appurtenances, engineering services and building space, will be in the 

range of $3 - 4 million per unit. As a result, total costs nationwide will be in the range of: 

$150 million - $200 million for fluidized bed incinerators 

$375 million - $500 million for multiple hearth incinerators 
5. Reduction in Hydrogen Chloride 

At this time, we do not know of any method to reduce hydrogen chloride 

 emissions from sewage sludge incinerators. 

 

6. Potential Cost Summary 

Pollutant Removal System Fluidized Bed 

Incinerators 

Multiple Hearth 

Incinerators 

Particulate matter 

and metals 

Advanced Scrubbing 

System $60 - 90 million $155 - 220 million 

Particulate matter 

and metals 

Wet Electrostatic 

Precipitators $125 - 150 million $310 - 375 million 

Sulfur Dioxide and 

Oxides of Nitrogen 

Sodium 

Hydroxide $12.5 - 15 million $31 - 38 million 

Condensable 

particulate matter 

and PM2.5 Unknown Unknown Unknown 

Oxides of Nitrogen Urea $75 - 100 million $185 - 250 million 

Mercury Activated Carbon 

Adsorbing System $175 - 200 million $438 - $500 million

Mercury Activated Carbon 

Injection + Baghouse $175 - 200 million $438 - $500 million

Carbon Monoxide Afterburners $150 - 200 million $375 - 500 million 

Hydrogen Chloride Unknown Unknown Unknown 

Individual Cost Ranges $773 - 955 

million 

$1, 932 – 2,383 

million 

Total Cost Ranges 

 

$2,705 – 3,338 

million 

The costs to comply with potential MACT Standards will result in substantial cost 

increases for the POTWs and their rate payers (i.e., customers). 

 

RPD 

11-23-09