CONTROLLING MERCURY AND SELENIUM EMISSIONS FROM COAL-FIRED COMBUSTORS USING A NOVEL REGENERABLE NATURAL PRODUCT

FOSSIL FUEL COMBUSTION SOURCES ARE THE LARGEST SINGLE CONTRIBUTOR OF ATMOSPHERIC MERCURY EMISSIONS AND THE SECOND LARGEST CONTRIBUTOR OF ATMOSPHERIC SELENIUM. OF ALL THE TRACE METALS CONTAINED IN COAL, MERCURY AND SELENIUM ARE OF GREATEST CONCERN SINCE THEY ARE THE MOST VOLATILE OF THE METALS, THEY ARE WIDESPREAD AND RELATIVELY TOOXIC, AND THEY DEPOSIT IN BIOSYSTEMS. IN ANTICIPATION OF FUTURE EMISSIONS REGULATIONS, THERE IS A NEED TO DEVELOP MEASURES THAT WILL CONTROL THESE SPECIFIC METALS. THESE METALS ARE DIFFICULT TO COLLECT BECAUSE OF UNUSUAL CHEMICAL AND PHYSICAL PROPERTIES. ALTHOUGH SELENIUM IS REMOVED IN VARIOUS DEGREES BY FLUE GAS DESULFURIZATION SYSTEMS, CONTROL SYSTEMS ARE NOT DESIGNED SPECIFICALLY TO CONTROL SELENIUM. EXISTING MERCURY CONTROL SYSTEMS RELY ON THE USE OF SORBENTS OR WET-SCRUBBING EQUIPMENT. IN ADDITION, ONCE THE MERCURY IS CAPTURED, THESE SORBENTS MAY BECOME HAZARDOUS WASTES THAT MUST BE DISPOSED OF. FURTHERMORE, CONTROL SYSTEMS DO NOT PROVIDE CONSISTENT REMOVAL EFFICIENCIES FOR MERCURY. THEREFORE, A UNIQUE NATURALLY-OCCURRING SORBENT TO CAPTURE MERCURY AND SELENIUM WILL BE DEVELOPED IN PHASE I. A SIGNIFICANT BENEFIT OF THE SORBENT IS ITS REGENERABILITY, WHICH ALLOWS THE ADSORBED METALS TO BE RECOVERED FOR RE-USE AND ELIMINATES THE GENERATION OF HAZARDOUS WASTES. PROCESS ECONOMICS ARE EXPECTED TO BE FAVORABLE SINCE THE SORBENT IS A RE-CYCLED NATURAL PRODUCT, IT CAN BE REGENERATED FOR RE-USE, AND THE ADSORBED METALS CAN BE RECOVERED.