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 Chlorinator Vacuum Loss; and Pump Maintenance. This time, you can test your knowledge about facultative lagoons, and hypotonic solutions.
Wastewater Treatment Sample Question
What is the recommended operational layout of a multicell facultative lagoon during the summer (or warmer) months?
A. Tangential operations
B. Parallel operations
C. Series operations
D. Single-cell operations
Answer: The answer to this question is C. Facultative lagoons operated in series mode during warmer or summer months allow for reduced effluent solids. By operating in series, the solids (such as algae) are kept in the primary or secondary cells, and improves effluent qualities and possibly avoiding NPDES excursions (TSS). Proper operation of Lagoon systems is a basic knowledge point for many lower levels of Wastewater certification.
Water Treatment Sample Question
Which stream of water from a reverse osmosis membrane system is the most hypotonic?
A. Concentrate
B. Permeate
C. Reject
D. Feedwater
Answer: The correct answer is B. Reverse osmosis is a membrane process capable of separating the water molecule from unwanted contaminants. During this process, the feedwater is pressurized through the membrane creating a stream of permeate or recovery water and a stream of concentrate or reject water. The permeated water is relatively free of contaminates and sometimes referred to as pure water. The lack of solutes in the permeated solution is what makes this solution more hypotonic than the hypertonic feedwater and reject water.
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.
