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Education/Training + Get AlertsWASTEWATER
By Rick Lallish
What test is done on influent and effluent samples to determine the volume of solids removed in clarifiers or ponds? What apparatus is used to run this analysis?
A. Total suspended solids, crucibles
B. Acid-to-alkalinity, beakers
C. Settleable solids, Imhoff cones
D. Settleability, settleometers
ANSWER: C. The settleable solids test is done using the Imhoff cones. The test measures the volume of settleable solids in one liter of sample that settles to the bottom in a one-hour period. The test may be done on influent or effluent and in clarifiers or settling tanks. The test should not be confused with the settleability test done on MLSS in activated sludge plants. More information may be found in the OWP, CSU-Sacramento textbook Operation of Wastewater Treatment Plants, Volume II, seventh edition, Chapter 16.
DRINKING WATER
By Drew Hoelscher
What is the percent strength in the solution mixing tank if an operator adds 96 gallons of chemical to 700 gallons of water?
A. 13.7%
B. 12.1%
C. 8.3%
D. 7.3%
ANSWER: B. It is common for a water operator to be tasked with making chemical dilutions at a treatment facility. In most cases this task is relatively simple, but an opportunity for error presents itself anytime chemical dilutions are performed.
(Chemical gallons / Total gallons) x 100 = % strength
(96 Chemical gallons / 796 Total gallons) x 100 = 12.06% strength
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.