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 Lagoon Walk-Throughs and Aging Water Samples. This time you can test your knowledge about types of trickling filters, and how to determine lead concentrations in drinking water.
Wastewater Treatment Sample Question
What type of trickling filter is best used for BOD reduction, but not for reporting purposes?
A. Nitrifying trickling filter
B. Low-rate trickling filter
C. Intermediate-rate trickling filter
D. High-rate trickling filter
Water Treatment Sample Question
Using the data in the table, what is the 90th percentile concentration for lead?
A. 12.82 ug/L
B. 13.25 ug/L
C. 13.86 ug/L
D. 7.26 ug/L
To see the answers to both the above questions, click this link.
About the authors: Rick Lallish is the Water Pollution Control program director at the Environmental Resources Training Center (ERTC) 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.
