10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
These 10 free QRO questions are organized by exam domain, so you can see how each part of the QRO - Certification for Municipal Solid Waste Combustion Facilities Operator - Combustion System Operator blueprint is tested. Reveal the answer and explanation under each question.
An upstream recovery line now removes more glass from incoming municipal solid waste without removing water or combustible material. The furnace continues to receive the same mass of the remaining waste per hour. Which change should the operator anticipate?
Correct answer: A - Greater thermal input per hour, because each kilogram of residual waste contains less inert material.
A representative ash lot produces three validated laboratory results: total lead, 410 mg/kg of solid ash; TCLP lead, 3.4 mg/L of extract; and TCLP mercury, 0.34 mg/L of extract. Under the federal toxicity-characteristic rule, which conclusion follows?
Correct answer: C - The mercury extract establishes the toxicity characteristic because it exceeds the 0.2 mg/L threshold.
At a transfer station, a loaded vehicle weighs 31,800 kg. Its stored tare is 12,000 kg, but equipment added to the vehicle has increased the tare to 12,600 kg. The new tare was verified on the serviceable scale in the same vehicle configuration and is approved for this ticket. The allowable waste payload is 19,500 kg; all other transport conditions are satisfied. Which ticket entry and disposition are correct?
Correct answer: D - Record 19,200 kg of waste and release the vehicle.
CO spikes persist at a steady furnace load even though outlet O2 and measured chamber temperatures remain within their approved ranges. Which additional finding would most strongly support poor gas-air mixing?
Correct answer: D - Several secondary-air nozzles are plugged despite an unchanged total combustion-air flow.
A wet scrubber uses sodium hydroxide to neutralize hydrogen chloride. Downstream treatment brings the dilute blowdown to its required pH and removes most suspended solids, but the dissolved-chloride concentration changes little. Why has clarification not removed the chloride along with the ash?
Correct answer: B - Neutralization forms soluble sodium chloride; gravity settling removes suspended solids rather than dissolved ions.
A centrifugal scrubber-recirculation pump develops a gravel-like rattle and fluctuating discharge pressure as the pressure drop across its suction strainer increases. Tank level, liquid temperature, pump speed, and valve positions have not changed. A suction-side leak check passes. What mechanism best explains this combination?
Correct answer: B - Restricted suction causes vapor bubbles to form and then collapse as pressure recovers inside the pump.
During a shift handover at a two-chamber controlled-air combustor, the incoming operator questions a primary-air setting of 55% of theoretical air. The unit is at its approved operating settings; secondary-air delivery is verified, secondary-chamber temperature is in range, and outlet CO is low and stable. All feed permissives are satisfied. The incoming operator proposes stopping waste feed until primary air reaches 100% of theoretical. How should this proposal be handled?
Correct answer: B - Retain the primary/secondary air split and continue monitoring final combustion performance.
The approved quality-assurance procedure for a CO monitor accepts zero and upscale errors no greater than 2% of span. Its range is 0-250 ppm. Before any adjustment, zero gas reads 1 ppm and a certified 150 ppm gas reads 154 ppm. Both readings are stable, all other required checks pass, and plant operating conditions are satisfactory. What is the correct disposition?
Correct answer: C - Accept both checks; the larger error is 1.6% of span, and the as-found readings should be recorded.
The induced-draft fan trips during firing. Furnace pressure becomes positive, and smoke begins escaping around a charging-door seal. Which control-room response has priority as the draft-loss emergency procedure is initiated?
Correct answer: A - Confirm that waste feed and auxiliary fuel are isolated and keep personnel away from the gas-release area.
A fabric filter's differential pressure suddenly falls while its outlet bag-leak detector and opacity monitor both rise. Gas flow is unchanged, compressed-air cleaning is functioning normally, and the readings have been verified. This combination should direct the operator's investigation toward:
Correct answer: D - A torn bag or failed bag seal allowing dirty gas to bypass filtration.
The full bank has 1,020 more QRO questions with explanations.
Continue in the free practice test →
View plans