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 Sequencing Batch Reactors and Chlorine Gas Withdraw Rate. This time you can test your knowledge about oxidation ditch detention time and liquid chlorine storage.
Wastewater Treatment Sample Question
An oxidation ditch has a volume of 1,560,000 gallons. If the flow to the oxidation ditch is 980,000 gallons per day, what is the detention time in hours?
A. 15.1 hours
B. 38.2 hours
C. 76.2 hours
D. 90.4 hours
Water Treatment Sample Question
What temperature should be maintained in a room storing liquid chlorine containers?
A. Less than 50 degrees F so the cylinders or containers do not build up pressure.
B. At least 65 degrees F, but not to exceed 100 degrees F.
C. Greater than 100 degrees F or the liquid will not convert to a gas.
D. Temperature is not important because the containers are sealed carbon steel vessels.
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.
