Sorbent Traps for Continuous Measurement of Metal HAP Emissions - Phase II

During this Phase II SBIR research project, Ohio Lumex will complete development of a sorbent trap method for continuous emissions monitoring of metal hazardous air pollutant (HAP) emissions. If method sensitivity is sufficient and the method is approved by EPA, it may also be used as an alternative to Method 29 for short-duration testing. Metal HAP emissions from stationary sources are currently determined using emissions factors derived from intermittent stack testing measurements, input feed stream data, and plant operating parameters. Emissions factors may have significant uncertainty, particularly for sources where feed stream metal content is highly variable. Continuous measurements are needed to provide superior accuracy, but current technology is limited and cost prohibitive. The proposed technology would meet that need with repetitive in-stack sampling using paired sorbent traps with periodic analysis of time-integrated samples collected over a period of several days. This approach is analogous to EPA Performance Specification 12B. This innovative and performance-based method will include robust quality controls, including pair agreement, breakthrough measurements, and spike recoveries. Technical feasibility was established during Phase I for three candidate sorbent traps, each using a different sorbent material. During Phase I, most simulated stack gas spike recoveries were measured within 75-125%. Phase II will optimize sorbent trap production, sample digestion, and analytical processes to improve these results, ensuring all target metals are recovered within an acceptable range, while also efficiently capturing and retaining metals from the sample gas stream. The sorbent trap method will be compared to Method 29 using Method 301 criteria. The proposed method is designed with particular focus on continuous sampling for hazardous waste combustors, metal smelting operations, iron and steel production, secondary smelting facilities, and coal-fired power plants. There are approximately 3300 individual point sources in the United States that fall within these categories. For continuous measurements, stationary sources will purchase these traps for use with continuous sampling equipment. For shortterm sampling as an alternative to Method 29, the customers are stack testing companies. Other customer categories will be discussed in the proposal. Continuous measurement of metal HAP emissions will improve EPA’s air emissions inventory and allow point sources to better understand their emissions. Sources that utilize control technologies to remove metals from the gas stream can use this information to optimize controls. For short-term testing, this method will benefit stack testers, who almost universally agree Method 29 is cumbersome, expensive, and hazardous.