August 7, 2012

Technical Demonstration for Negligible Impact to Air Quality

For the Amendment to 

10 CSR 10-6.400 Restriction of Emission of Particulate Matter from Industrial Processes

Background

The Missouri Air Conservation Commission (MACC) adopted an amendment to 10 CSR 10-

6.400 Restriction of Emission of Particulate Matter from Industrial Processes on October 28, 

2010. The amendment added an alternative compliance method for wet corn milling drying 

operations. Prior to the amendment, wet corn milling drying operations were required to operate 

a control device capable of 99.5% control efficiency by weight and there was no outlet 

concentration limit that could be used in lieu of the control efficiency requirement. When 

investigating the origin of this requirement, the Missouri Department of Natural Resources’ Air 

Pollution Control Program was unable to determine the reason this level of control was 

specifically required for these types of operations. It is believed that the rule language was likely 

borrowed from a different state’s rule originally written to control total suspended particulate 

matter (TSP) emissions, which would make 99.5% control efficiency by weight much easier to 

achieve when considering the removal of particles much larger than PM10. 

In late 2009, National Starch and Chemical Company (National Starch) requested a variance 

from this rule requirement, as it was demonstrated that due to their clean upfront process and 

resulting low inlet concentration of PM10, 99.5% control efficiency was not possible. Their inlet 

PM10 concentration is 0.09 grains/dry standard cubic foot (grain/dscf). Therefore, in order to 

achieve 99.5% control efficiency, their outlet concentration would need to be 0.00045 grain/dscf. 

The department’s Air Pollution Control Program is unaware of any type of control technology

that could guarantee this level of control.

National Starch currently has a wet scrubber in operation to control particulate matter emissions 

from their wet corn milling drying operation units, which is able to guarantee a control efficiency

of 99% for inlet concentrations ranging from 1 – 2 grain/dscf. For National Starch’s much lower 

inlet concentration, the scrubber can only guarantee an outlet concentration of 0.01 grain/dscf, 

which equates to a control efficiency of approximately 88.9%. The next level of control would 

be a bag house, which could only guarantee a level of control down to 0.005 grain/dscf (a control 

efficiency of about 94.4%). This still would not achieve the 99.5% control efficiency required in 

the rule, and due to the high moisture content of the emissions from these units, it is unlikely that 

a bag house would be able to work as designed.

In March 2010, the MACC granted a variance to National Starch from this rule requirement, and 

the department’s Air Pollution Control Program began developing a rule amendment to address 

this issue. Through the rulemaking, an alternative compliance method based on an outlet 

concentration of 0.01 grain/dscf was added to the rule, which could be used to comply with the 

rule in lieu of the 99.5% control requirement for wet corn milling drying operations.

Negligible Impact to Air Quality Demonstration
There are only two sources in the state that the wet corn milling drying operations requirement in 

10 CSR 10-6.400 applies to. In addition to National Starch, the other wet corn milling drying 

operation is owned by Lifeline Foods, which operates with a much higher inlet concentration of 

PM10 emissions, making the 99.5% control efficiency easier to meet than the alternative 

compliance method based on a 0.01 grain/dscf outlet concentration limit. Therefore, this 

amendment is not expected to have any impact on the control requirements for Lifeline Foods.

With their wet scrubber in operation (outlet concentration of 0.01 grain/dscf), National Starch 

currently has a controlled potential to emit of 3 ton/year of PM10. National Starch investigated 

the Environmental Protection Agency’s (EPA’s) Best Available Control Technology databases 

and found no control technology that could guarantee an outlet particulate matter concentration 

of less than or equal to 0.00045 grain/dscf, which would be required to achieve 99.5% control 

efficiency. The most stringent technology that could be applied would be a bag house, which 

could only guarantee a level of control of 0.005 grain/dscf, and as stated above, a bag house 

likely could not function properly because of the high moisture content of the emissions 

associated with a wet corn milling drying operation process. However, if a bag house were 

applied this would only provide an additional 50% control, reducing the controlled potential to 

emit from 3 ton/year to 1.5 ton/year and equating to a cost of over $200,000/ton of PM10

removed.

The hypothetical control scenario of implementing a bag house—the most stringent technology

available—for National Starch’s wet corn milling drying operation would result in an 

insignificant reduction in overall PM10 emissions. Table 1 below shows EPA’s 2008 National 

Emissions Inventory data for PM10 emissions in Missouri for 17 source sectors. As can be seen, 

2008 PM10 primary emissions in Missouri totaled 882,813.58 tons (actual emissions). The 

difference of 1.5 tons of controlled potential emissions from a single source equates to less than 

0.0002% of the statewide actual PM10 emissions from 2008, which would be expected to result 

in a negligible impact to overall air quality in the state.

Table 1. 2008 PM10 Emissions for the State of Missouri from the National Emissions Inventory

State Source Sector Pollutant Code DESCRIPTION

2008 Emissions 

(Tons)

MO Fuel Comb. Elec. Util. PM10-PRI PM10 Primary (Filt + Cond) 10,124.7

MO Fuel Comb. Industrial PM10-PRI PM10 Primary (Filt + Cond) 792.54

MO Fuel Comb. Other PM10-PRI PM10 Primary (Filt + Cond) 6,367.80

MO Chemical and Allied Product Mfg. PM10-PRI PM10 Primary (Filt + Cond) 437.12

MO Metals Processing PM10-PRI PM10 Primary (Filt + Cond) 889.57

MO Petroleum and Related Industries PM10-PRI PM10 Primary (Filt + Cond) 45.83

MO Other Industrial Processes PM10-PRI PM10 Primary (Filt + Cond) 14,777.45

MO Solvent Utilization PM10-PRI PM10 Primary (Filt + Cond) 120.03

MO Storage and Transport PM10-PRI PM10 Primary (Filt + Cond) 1,774.12

MO Waste Disposal and Recycling PM10-PRI PM10 Primary (Filt + Cond) 5,093.22

MO Highway Vehicles PM10-PRI PM10 Primary (Filt + Cond) 9,808.44
MO Off

-Highway PM10-PRI PM10 Primary (Filt + Cond)6,404.78

MO Miscellaneous PM10-PRI PM10 Primary (Filt + Cond) 806,178.0

MO Total Emissions PM10-PRI PM10 Primary (Filt + Cond) 862,813.58