Exam Study Guide - December 2019

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WASTEWATER - By Rick Lallish

During an afternoon plant walk-through, you notice a thin, light-tan foam covering approximately 10% to 25% of the aeration basins. What condition does this indicate?

A. Normal conditions

B. Startup conditions

C. Nocardia filaments

D. Old sludge (long solids retention time, low food/microorganism ratio)

Answer: A. The ability to interpret visual conditions in an activated sludge facility is vital to successful operations. A thin, light-tan foam is normal. The startup condition is usually a thick, white, billowy foam; Nocardia typically appears as a thick, greasy and dark-tan foam. Old sludge usually presents thick, scummy and dark-brown foam. Knowing these conditions will help operators troubleshoot and operate an activated sludge facility efficiently and professionally. More information may be found in the Water Environment Federation textbook: Wastewater Treatment Fundamentals I – Liquid Treatment, Chapter 8.

DRINKING WATER - By Drew Hoelscher

What is the recommended location for a newly installed service line?

A. 45 degrees up from the bottom of the main

B. At the bottom of the main

C. At the top of the main

D. 45 degrees down from the top of the main

Answer: D. Tapping a water distribution main 45 degrees from the top helps eliminate any accumulated trapped air in the top portion of the main and any accumulated sediment in the bottom portion of the main from entering the service line. It is also important to install service lines below the deepest anticipated frost lines for that area and to provide a means of slack by laying the line in a downward S-curve formation from the tap.

About the authors

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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