Welcome back to TPO magazine's Exam Study Guide Series, which offers a pair of water/wastewater study questions with in-depth explanations of the answers. Last time, we covered a set of wastewater and drinking water treatment questions on the topics of Rotating Biological Contactors and PFAS MCLs. This time you can test your knowledge about sewer velocity and incubator temperatures.
Wastewater Treatment Sample Question
A ping-pong ball travels from manhole A to manhole B 200 feet away in 1.5 minutes. The sewer line is a 6-inch sewer main. The line is running full. What is the velocity in this sewer main? Bonus - Is it within recommended speed?
A. 0.9 feet per second
B. 1.48 feet per second
C. 2.22 feet per second
D. 3.42 feet per second
Water Treatment Sample Question
An operator is instructed to prepare a total coliform analysis for process control. What temperature should the incubator be set at?
A. 20 degrees C (plus or minus 0.5 degrees)
B. 25 degrees C (plus or minus 0.5 degrees)
C. 35 degrees C (plus or minus 0.5 degrees)
D. 40 degrees C (plus or minus 0.5 degrees)
To see answers for both of the above questions, click this link.
About the authors: Rick Lallish is the Water Pollution Control program director at the Environmental Resources Training Center of Southern Illinois University-Edwardsville. He provides training for entry-level operators in the wastewater field and operators throughout the state looking to further their education. Lallish was also named the 2017 Illinois Operator of the Year and 2018 president of the Illinois Association of Water Pollution Control Operators.
Drew Hoelscher is the program director of drinking water operations at the Environmental Resources Training Center in Edwardsville, Illinois.
