Exam Study Guide: Volatile Solids Calculations and Bacteriological Sampling

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: Volatile Solids Calculations and Bacteriological Sampling

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 Types of Blowers and Evaluating Water Quality. This time you can test your knowledge about volatile solids calculations, and bacteriological sampling.

Wastewater Treatment Sample Question

A digester is being fed with sludge that is 60% volatile solids. The sludge withdrawn is 40% volatile solids. What is the percent reduction in volatile solids?

A. 20%
B. 39.6% 
C. 55.6%
D. 67.1%

Water Treatment Sample Question

How many repeat bacteriological (total coliform) samples should an operator collect if a routine bacteriological sample is total coliform positive?

A. One
B. Two
C. Three
D. Zero, repeat samples are only required if the sample tests positive for E. coli.

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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