Exam Study Guide: Preliminary Treatment Safety; and Sulfuric Acid Titration

Maintaining your education is important, especially in a career that demands licensing exams. Prove you’re an expert operator by answering these questions and others from our Exam Study Guide Series.

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 Imhoff Tank Maintenance; and Water Softening Math. This time, you can test your knowledge about preliminary treatment safety, and sulfuric acid titration.

Wastewater Treatment Sample Question

What safety concerns may be present in the preliminary treatment process?

A. Hydrogen sulfide
B. Waterborne diseases
C. Physical accidents/hazards
D. Explosive mixtures/gases

Answer: The answer to this question is A, B, C and D. The preliminary treatment area is one of the most hazardous areas of the treatment plant. Any of the safety concerns listed in the question are viable concerns. Hydrogen sulfide and explosive gases such as methane are possible due to long runs in collection systems and organisms consuming dissolved oxygen. Waterborne diseases are an everyday hazard in the industry. Personal hygiene and laundering work clothing (separate from all other home laundry) are key ways to avoid these diseases. Finally, physical accidents are always possible due to wet conditions, mechanical equipment, spills and electrical hazards. Good operator safety awareness is a key component to operator training and development. 

Water Treatment Sample Question

What is an operator measuring when titrating sulfuric acid into a sample of water and stopping at a pH of 8.3?

A. Total alkalinity
B. Carbonate alkalinity
C. Bicarbonate alkalinity
D. Total hydroxide and one half the carbonate alkalinity

Answer: The correct answer is D. In order to measure the alkalinity in raw and treated water at a water purification plant, the operator typically collects a 50 ml or 100 ml water sample and adds phenolphthalein indicator. If the pH of the water sample is above 8.3, the sample of water will turn pink. The operator will decrease the pH to 8.3 by titrating sulfuric acid into the sample. At this time, the operator makes note of the milliliters of sulfuric acid used to determine the P alkalinity.

In other words, the P alkalinity is the measurement of the total hydroxide and one half the carbonate alkalinity. The operator then proceeds to determine the total alkalinity by adding another indicator and titrating with sulfuric acid until the correct pH end point has been reached. 

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.


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