Exam Study Guide: Solids Retention Time and Total Trihalomethanes

Maintaining your education is important, especially in a career that demands licensing exams. Prove you’re an expert operator by answering these questions and others from our Exam Study Guide Series.

Exam Study Guide: Solids Retention Time and Total Trihalomethanes

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 Secondary Clarifier Denitrification and New Groundwater Sources. This time you can test your knowledge about solids retention time and total trihalomethanes.

Wastewater Treatment Sample Question

Solids retention time (SRT) is an important process control measure, what does it mean?

A. How long the flow remains in the system
B. How much time it takes for the stalk ciliates to populate 
C. How long a suspended solids particle remains under aeration
D. How long the bacteria remains in the secondary clarifier

Water Treatment Sample Question

How many disinfectant byproducts (DBPs) make up the total trihalomethanes (TTHMs)?

A. Two
B. Three
C. Four
D. Five

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 (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.


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