Air Emission Monitoring & Control Flashcards

Which control technology is most effective for removing fine particulate matter (PM2.5) from industrial exhaust streams?

Answer: Fabric filter (baghouse)

Fabric filters (baghouses) achieve collection efficiencies exceeding 99% for fine particulate matter, outperforming mechanical separators and simple wet scrubbers for PM2.5.

Under the EPA's New Source Performance Standards (NSPS), what regulatory concept triggers applicability when a facility makes a 'major modification'?

Answer: Prevention of Significant Deterioration (PSD) review

A major modification at a major stationary source in an attainment area triggers PSD review under the NSPS framework, requiring BACT analysis and air quality impact assessment.

An environmental auditor reviewing a facility's CEMS records finds that the monitor was out of service for 12% of the operating hours in a quarter. What is the likely regulatory concern?

Answer: Both A and B are likely concerns

Excess monitor downtime above the allowed threshold (typically 5% under Part 75) is a violation, and missing data periods require substitution with conservative values, making both regulatory concerns valid.

What does the opacity standard of 20% (6-minute average) primarily regulate under EPA Method 9?

Answer: The visual obscuration caused by particulate-laden exhaust from a stack

EPA Method 9 visual opacity is a surrogate measure of particulate emissions, assessing the degree to which stack exhaust obscures light as observed by a trained, certified observer.

Which of the following best describes Selective Catalytic Reduction (SCR) as an NOx control technology?

Answer: It removes NOx by injecting ammonia or urea into the flue gas upstream of a catalyst

SCR systems inject ammonia (or urea that hydrolyzes to ammonia) into exhaust gas, where it reacts with NOx over a catalyst to produce harmless nitrogen gas and water vapor.

What is the significance of the 'Class I area' designation under the Clean Air Act for an air quality permit applicant?

Answer: Visibility and air quality receive the highest level of protection, imposing stricter PSD increment limits

Class I areas (such as national parks and wilderness areas) have the most stringent PSD increment limits to preserve air quality and visibility, affecting nearby source permit conditions.

During a source test, a facility's measured NOx emission rate is 0.10 lb/MMBtu. The permit limit is expressed as 0.15 lb/MMBtu. Which statement is correct?

Answer: The facility is in compliance with 33% margin below the permit limit

Measured NOx of 0.10 lb/MMBtu is below the permit limit of 0.15 lb/MMBtu, demonstrating compliance with approximately a 33% margin.