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� Mr. Kevin Kain Mr. Tarfk Hanaty September 10, 2010 Page 6 -� ��i�i Moss & Barnett An �S Is required to address the differences in ope2ting Conditions between the proposed Bituminous Roseville Plant and the plants In North Carolina used to generete emissions factors for hydrogen suifide and the carbon bed used to control hydrogen sulfide emisslons and filter bed used to control volatlle organic compound and particulate emission. Carbon Bed/Carbon Flter — CE004 There is a lack of sufficfent information for making the condusion that the proposed air polluUon control technology will work in the manner nxessary to support the condusion that the plant will not have an adverse envlronmental fmpad. Bituminous Roadways proposes to vent asphalt storage tank emisslons, loading and unloading to a carbon bed filter to reduce volatile organic compound (VOC) an8 condensable particulate matter (PM) emissions. The targeted pollutant is hydrogen sulfide, which presents a disagreeable odor at very low concentradons. Carbon bed filters remove low-mncentratlon gases and vapors from an exhaust stream by adhering pollutants to the surface of porous solids. To a large extent the character of the material targeted for adsorption determines the applkabllity of carbon bed filters for poilution control. Key factors are a material's molecular wefght, vapor pressure and polarity. ^ The Bttumfnous Roadways permit appUcatlon uses 90°h as the desOVCtlon/conVOl efflciency for hydrogen sulfide for the carbon bed. This percentage calculation is cridcai bepuse it reFlects the effectiveness of the alr pollutlon contrd tedinology. Variatlon by a few percent can have a signiflcant impzc[ on amblent concenpations of the targeted polluWnt. For example, 'rf destruttlon/controi effldency for hydrogen sulflde were reduced from 90% to 70%, concentrations on and around our bulldin9 would exceed the hydrogen sWfide odor threshoids and hydrogen sulfide s[andards for New York, Kentucky and New Mexfco. We reviewed manufacturers' data from several carbon bed manufacturers. One manufacturer rated materials on a four point scale: "Excellent" with one pound of carbon adsorbing 25% of its own weigh of the materlal; "Good" with one pound of carbon adsorbing 15°k of its own weight; "Poor' with car6on adsorbing 5°k of the material by weight and none. This manufacturer rated the ability of carbon to adsorb hydrogen su�fide as "Poor." Other manufacturers rated the abilily of carbon to adsorb hydrogen sulflde as "Satlsfactory" (10�0- 20%), another 2ted i[ "Good" (16.6%), and another manufacturer rated the abillty of carbon to adsorb hydrogen sulfide as "6ccellent." This manufacturers data is availabie upon request. The dlvergence of carbon bed manufacturer opinion on the ability of carbon to adsorb hydrogen sulflde reises material questions as N the effectiveness of the controt technology. The absence of manufacturer data In the permft application is an unacceptable and glaring omission. With such a divergence of opinion and inherent uncertainty, it is imperetive for the Agency and the public to be able to evaluate the manufacturers data for this control Cechnology. The manufacturers' carbon bed data also show that carbon adsorbs many of the other constltuents of the waste stream (such as benzene) much better than it dces hydrogen sulfide. This suggesCS that whfle the orbon bed may initially adequately control hytlrogen sulflde emissions, its ability to do so may degrade rapfdly over tlme as other waste stream constituents