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 Solids Retention Time and Total Trihalomethanes. This time you can test your knowledge about anaerobic digester classifications and water hardness calculations.
Wastewater Treatment Sample Question
Which classification of anaerobic digester is the most efficient at pathogen reduction, increased volatile solids reduction and decreased detention times?
A. Heterophilic
B. Mesophilic
C. Thermophilic
D. ATAD
Water Treatment Sample Question
Using the data below, what is the approximate magnesium concentration in mg/L?
Total hardness = 470 mg/L as CaCO3
Calcium = 136 mg/L
Elements and atomic weights: Ca, 40.078; Mg, 24.304; C, 12.0096; O, 15.999
A. 3
B. 32
C. 147
D. 334
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.
