MEMORANDUM 

From: The Office of Air Quality Planning and Standards 

 U.S. Environmental Protection Agency 

To: EGU NSPS Docket (EPA-HQ-OAR-2011-0044) 

Date: March, 2011 

Subject: Multi-pollutant Control Technologies 

Introduction 

In addition to single pollutant controls, several emerging multi-pollutant technologies in various 

stages of commercial development are available to reduce emissions. These include technologies 

that offer the potential for improved environmental performance at lower costs than traditional 

technologies. The following is a brief summary of some of the multi-pollutant control technologies, 

including propriety technologies. This summary is not intended to be a comprehensive list of 

available technologies. The performance values given here are those that have been provided by the 

technology provider in publically available sources. Inclusion of a technology in this summary is 

not intended to be an endorsement of that technology by the US EPA the US Government 

Multi-pollutant Control Technologies 

Airborne ProcessTM

The Airborne ProcessTM employs a proprietary method of sodium bicarbonate regeneration that 

involves dry sodium bicarbonate injection, wet sodium scrubbing, and staging with oxidants. The 

sodium sulfate by-product (the end product after scrubbing of flue gas emissions has occurred) is 

regenerated into two end products. The first product is sodium bicarbonate for re-use in the 

scrubbing process, and the second is a salable fertilizer that is generated using a granulation process. 

It is projected to provide 99.5% removal of SO2, 98% removal of SO3 (sulfuric acid mist precursor), 

98% removal of NOX, and 90% removal of Hg from plant emissions. 

APTECH CST LLC (Clean Stack Technologies)

The APTECH CST process uses a slurry-injection technology to reduce SO2, SO3, NOX, mercury, 

chlorides, and prevent slagging with less than 0.4% parasitic power required. The technology is 

expected to achieve emissions reductions of greater than 70% for SO2 and NOX, close to 100% for 

SO3 and HCl, and potentially greater than 60% for Hg. 

CEFCO

The CEFCO Process integrates two technologies to selectively capture and remove flue gas 

pollutants and CO2 and then convert these captured pollutants into salable end-products or readily 

disposable waste streams. The first technology component (Ewan's shockwave "free-jet collision" 

scrubbing) applies a sequence of reactors and aero-coalescers to strip flue gas of metals, fine 
particulates, SOX, NOX, and CO2, and capture them as segregated products. The second technology 

component (the "Cooper Process") is a chemical process which uses chemical reagents for the 

selective conversion of each pollutant in succession, into concentrated forms of recovered metals, 

potassium sulfate fertilizer, potassium nitrate fertilizer, pure CO2, or readily disposable waste 

streams. As an integrated process, the CEFCO Process is designed to remove greater than 90% of 

CO2 and over 99% of all other pollutants from gas streams with less than 10% energy penalty or 

parasitic load burden. 

COMPLY 2000

The COMPLY 2000 process is a patented ozone-based technology designed to remove flue gas 

pollutants. As the flue gas exits the boiler, it passes through the O3 aspirator where the flue gas is 

mixed with O3 (Ozone) to convert NO to NO2, which, as a result, becomes water soluble. As the 

gas then enters the unit, it blends with the first fog field where a full gas–to–liquid contact takes 

place. The fogging process floods the product of combustion (POC) and fog mix with condensation 

nuclei, encouraging acid vapor forming hydrolysis reactions. The fogging spray is mixed with a 

hydrogen peroxide solution to provide SO2 conversion to sulfuric acid. 

As the mixed moist gas passes through the cooling coil, the condensing coils extract heat and the 

captured pollutants run off of the finned coil to the drain. The treated gas then passes through the 

second fog field where the moisture levels are elevated and the cooling coil is cleaned of any dirt or 

soot. From the second fog field, the clean gas passes through the condensing coil where any other 

heat is extracted, and the clean gas is cooled to lower temperatures. From the condensing coil, the 

clean cool gas is directed to the outside air. The wastewater enters the holding tank to be treated 

(acids to be neutralized). After treatment, it is recycled back to the high-pressure pumps for use in 

the foggers. The COMPLY 2000 process is designed to remove up to 98% of combustion emission 

pollutants such as NOX, SO2, Hg, and PM2.5, and capture up to 25% of the CO2. 

Copper-Oxide (CuO)

The Copper-Oxide (CuO) process is designed to remove SO2 and NOX from coal-fired boiler’s flue 

gas streams. The SO2 is absorbed on alumina spheres that are impregnated with copper. The 

reaction forms copper sulfate, which then acts as a selective reduction catalyst of NOX in the 

presence of NH3. The process consists of an absorber, regenerator, solids heater, and combustor. 

When the flue gas stream enters the absorber the SO2 is adsorbed by a sorbent and NOX is reduced 

by injecting NH3. The spent sorbent is transported to the solids heater where the sorbent is 

regenerated by contacting combustion gas from the natural gas combustor. The sorbent then is 

transported back to the adsorber for reuse. Current tests have shown the CuO process to remove 

90% of SO2 and NOX. 

Electro-Catalytic Oxidation (ECO®)

The Electro-Catalytic Oxidation (ECO) process removes flue gas emissions in a single adsorber 

vessel and the utilization of an integral WESP. The system phases are a gas converter stage, 

condensing WESP, and acid recovery system. The gas converter provides electrical oxidation of 

SO2, NOX, and Hg. The oxidized molecules then form particulates that, along with any SO2 and 

NO2 that were not converted to acids, are removed by the WESP. The ECO process is designed to 

remove up to 90% of NOX, 98% of SO2, 70% of Hg, 88% of HCl, and 90% of PM2.5 for a coal-fired 

power plant. 
Electron Beam Process (E-Beam)

The Electron Beam Process (E-Beam) process removes NOX and SO2 through a series of steps set 

up after the particulate matter control. The system consists of an evaporative spray cooler to cool 

the flue gas to 140-150°F. Gaseous ammonia is injected into the flue gas before the main process 

vessel. In the main process vessel, the flue gas is irradiated by a beam of high-energy electrons, 

while water is added as a coolant to counter the temperature rise. In this process, hydroxyl radicals 

and oxygen atoms are formed and oxidize SO2 and NOX, which mix with water from the flue gas to 

form sulfuric and nitric acids. The sulfuric and nitric acids are neutralized by NH3 and the products 

are ammonium sulfate and ammonium sulfate-nitrate, which are collected in the PM control device. 

The projected emission removal efficiencies are up to 90% for NOX and up to 95% for SO2. 

Indigo Multi Air Pollutant System (MAPSystemTM)

The Indigo Multi Air Pollutant System (MAPSystem) was designed to reduce SO2, NOX, PM, and 

Hg emissions through chemical, fluidic and electrostatic processes. Reagants oxidze the NOX and 

enable the removal of mercury, while sorbents remove acidic compounds. The fluidic process 

provides mixing to enhance removal efficiency. The flue gas then proceeds to the ESP or bag 

house. Projected removal efficiencies are up to 94% for Hg, up to 97% for SO2, and up to 54% for 

NOX. 

Nalco Mobotec techology

This process involves three technological components. T he addition of ROTAMIX technology for 

the injection of ammonia or urea lowers NOX emissions, while furnace sorbent injection (FSI) 

systems can be applied effectively to reduce SO2 and mercury emissions. FSI systems coupled with 

ROFA technology increase the contact/interface between sorbent and flue gas. This improved 

mixing reduces sorbent usage while maintaining desired emission levels. The combination of the 

ROFA, FSI, and ROTAMIX systems can reduce SO2 up to 98% and NOX up to 95% at relatively 

low auxiliary power requirements. 

NOXSO

THE NOXSO process is a dry, regenerable system capable of removing both SO2 and NOX in flue 

gas from coal-fired utility boilers burning medium-to-high sulfur coals. The flue gas passes through 

a fluidized-bed adsorber downstream of a precipitator. The SO2 and NOX are adsorbed by the 

sorbent. The NOX is desorbed and recycled to the boiler. The sulfur is regenerated and reacted with 

methane to produce an off-gas with a high SO2 concentration. This gas is used to produce 

elemental sulfur. The projected removal efficiencies for SO2 are up to 98% and for NOX are up to 

90%. 

Pahlman ProcessTM

The Pahlman ProcessTM uses the PahlmaniteTM sorbent mineral powder to adsorb SOX, NOX, and 

Hg. The technology can remove multiple pollutants by a single, dual or multi stage dry process and 

does not require NH3. The process creates end products that can be used to make detergents, 

fertilizers, and food preservatives. Removal efficiencies of greater than 99% for SOx and NOx and 

greater than 65% for Hg have been reported. 
ReACTTM

The ReACTTM process controls SO2, NOX, Hg and PM in a multistage regenerative process that 

produces salable byproduct. A moving bed adsorber provides contact between flue gas 

(downstream of a primary particulate control device, typically an electrostatic precipitator) and 

activated coke pellets, where SO2, SO3, NOX, and Hg are adsorbed onto the carbon surfaces. 

Ammonia is injected upstream in order to promote the SO2 and NOX reactions. The moving bed 

acts as a particulate collection step as the impingent of the flue gas on the activated coke pellets 

provides "polishing" control of particulate. 

Activated coke from the adsorber is then processed in a regenerator vessel which completes the 

reduction of NOX to N2, and drives off SOX in a concentrated sulfur rich gas stream. Adsorbed 

mercury is retained in the activated coke in a region of the regenerator where temperature 

conditions allow the mercury to accumulate. Regenerated activated coke is screened to remove 

fines and returned to the absorber. Sulfur rich gas is then processed using conventional technology 

to produce salable sulfuric acid. 

This completely dry process does not evaporate any water into the gas stream. It can reduce SO2

and SO3 emissions to greater than 98%, NOX capture can be in the range of 30 to 60%, mercury 

capture is in the range of 90%, and a net reduction of particulate in the range of 50% is expected. 

SkyMine®

Skyonic’s SkyMine® technology is a post-combustion system that reacts flue effluent with sodium 

hydroxide and pulls CO2 out to form sodium bicarbonate ("better-than-food-grade baking soda") 

while also removing heavy metals and acid gases. The process uses energy in the form of waste 

heat from the plant. In addition to capturing and mineralizing CO2, the process cleans SOX and NO2

from the flue gas, and removes heavy metals such as mercury. The process is reported to permit the 

removal of up to 99% of the CO2 and virtually all of the SO2, NO2, Hg, and other heavy metals. 

SNOXTM

The SNOX process is a catalytic flue gas cleaning process. The process generates no secondary 

sources of pollution, such as waste water, slurries or solids. It consumes no water or materials, 

except for ammonia for the catalytic NOX reduction. The principal SNOX process steps are dust 

removal in ESP (or bag filter); heating of the flue gas to about 400°C; catalytic reduction of NOx by 

NH3 added to the gas upstream of the DeNOx-reactor; catalytic oxidation of SO2 to SO3 in the 

subsequent oxidation reactor; cooling of the gas to about 260°C; and, further cooling of the gas to 

about 100°C in the "WSA Condenser", a falling film condenser and concentrator with vertical glass 

tubes, whereby the SO3 and H2SO4 vapor is condensed and separated as concentrated sulfuric acid 

from the bottom chamber of the condenser. 

SNOX removes up to 99% of SO2 and SO3 and up to 96% of the NOX in flue gases. The sulfur is 

recovered as 94 – 96% concentrated sulfuric acid of high purity. NOX is catalytically reduced by 

ammonia to nitrogen and water. Essentially all dust and particulates are removed from the flue gas. 

The heat produced in the process and by cooling of the flue gas to 100°C is recovered as steam and 

preheating of combustion air, thus increasing boiler thermal efficiency and gross power production. 
The process is in particular suited for boilers burning high sulfur refinery residues, such as 

petroleum coke (petcoke), orimulsion, heavy oils and tars and sour gases. 

SOx-NOx-Rox Box

The SOx-NOx-Rox Box (SNRBTM) involves two technological components. High-temperature 

filter bags and circular monolith catalyst developments enable multiple emission controls in a single 

component with a low plan-area space requirement. The high-temperature bag provides a clean, 

high-temperature environment compatible with effective SCR operation, and a surface for enhanced 

SO2/sorbent contact. SO2 removal is accomplished using either calcium- or sodium-based sorbent 

injected into the flue gas. The NOX removal is accomplished by injecting ammonia (NH3) to 

selectively reduce NOX in the presence of a selective catalytic reduction (SCR) catalyst. Particulate 

removal is accomplished by high-temperature fiber bag filters. The SNRBTM can achieve greater 

than 70% SO2 removal and 90% or higher reduction in NOX emissions while maintaining 

particulate emissions below 0.03 lb/MMBtu.