Exam Study Guide - October 2022

Licensing exams can be challenging. Our Exam Study Guide helps you prepare by presenting questions similar to those on an actual exam. You can find many more sample questions on the TPO website at www.tpomag.com/study.

Interested in Education/Training?

Get Education/Training articles, news and videos right in your inbox! Sign up now.

Education/Training + Get Alerts


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.


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 


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.  


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.