Exam Study Guide


By Rick Lallish

Conditions recognized as major operating problems causing poor performance or failure of wastewater collections systems are known as what?

A. Industrial discharges

B. Peripheral lateral discharges

C. Inflow and Infiltration

D. Fouled lift stations

Answer: C. Inflow and infiltration problems have been overlooked for decades. Many municipalities have adopted the out-of-sight, out-of-mind approach. This has caused many to scramble to find funds to correct for years of neglect. Inflow and infiltration problems are the leading cause of excessive hydraulic overloads, private-home sewage backups, and premature failure of the collection system. More information may be found in the OWP, CSU-Sacramento textbook: Operation and Maintenance of Wastewater Collection Systems (Eighth Edition), Chapter 4.


By Drew Hoelscher

What does the CT value represent in water treatment?

A. How smooth the inner wall is on a piece of pipe

B. A measure on how effective a disinfectant is in pathogenic inactivation

C. The size of particle passing through a particle counter

D. The electrical charge of a coagulant

Answer: B. The effectiveness of oxidants varies when treating water for pathogenic organisms. Most water treatment manuals list chlorine, chloramines, ozone and chlorine dioxide as the most commonly used options. Knowing each oxidant will perform differently, an operator can rely on the calculated CT value to ensure the appropriate log removal/inactivation of pathogens is obtained.

About the author(s)

Rick Lallish is water pollution control program director and Drew Hoelscher is program director of drinking water operations at the Environmental Resources Training Center of Southern Illinois University Edwardsville.


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