Methodology for characterizing emissions from small (0.5–2 MTD) batch-fed gasification systems using multiple waste compositions

Abstract

A compact, containerized gasification system was characterized for air emissions while burning four waste types. A methodology is presented for developing a standardized test waste composition and demonstrated using three military and one civilian waste types. Batch charges of waste were processed through a gasification chamber, afterburner, and wet scrubber. The 0.5–2 metric ton per day (MTD) system was designed for mobile deployment by the military in forward operations but would be applicable to small scale civilian applications. Emissions data from these types of small capacity, cyclically operated systems are lacking, limiting efforts to compare technologies and their environmental performance. Eight tests were conducted in a 7-day period at the Kilauea Military Camp (KMC) in Hawaii. The pollutants characterized were chosen based on their regulatory and health relevance: particulate matter (PM), mercury (Hg), elemental composition, volatile organic compounds (VOCs), polyaromatic hydrocarbons (PAHs), and polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Averaged data from 4-hour runs, including startups and shutdowns, indicated that five of the nine EPA-regulated compounds (lead, cadmium, Hg, sulfur dioxide, and hydrogen chloride) were under the emission limits set for Other Solid Waste Incineration Units (OSWI) while four, PCDD/PCDF, PM, nitrogen oxides, and carbon monoxide, were higher. The procedures through which waste compositions were created and emissions were characterized provide a methodology by which differing waste to energy technologies can be compared on an equivalent basis. This system’s emissions compare favorably with alternative disposal methods. PM and PCDD/PCDF emission factors were, respectively, over 39 and 9 times lower from this unit than from published data on burning simulated military waste in an air curtain incinerator and in open burn piles (“burn pits”).