Plant Operations Practice Questions for Washington Level I

1. Question 1

   What is the basic job of a surface aerator?

   1. Settle biological solids below the surface
   2. Add oxygen and circulate basin water
   3. Measure oxygen and record basin readings
   4. Remove foam from the basin surface
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   Answer: B. Add oxygen and circulate basin water

   A surface aerator moves water at the basin surface to transfer oxygen and provide mixing.

2. Question 2

   What happens in a trickling filter?

   1. Media circulates through an aeration basin
   2. Sludge settles beneath rotating treatment discs
   3. Air carries wastewater around dry media
   4. Wastewater flows over attached-growth media
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   Answer: D. Wastewater flows over attached-growth media

   A trickling filter distributes wastewater over media where attached microorganisms help remove biodegradable waste.

3. Question 3

   What is the basic purpose of tertiary filtration?

   1. Inactivate organisms before discharge
   2. Remove remaining suspended particles
   3. Measure the final effluent flow rate
   4. Increase chlorine residual after filtration
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   Answer: B. Remove remaining suspended particles

   Tertiary filtration removes particles that remain after secondary treatment, helping further polish the effluent.

4. Question 4

   How does a wastewater sand filter remove particles?

   1. Pass water across rotating filter panels
   2. Strain water through a surface screen
   3. Pass water through sand or similar media
   4. Hold water still so particles can settle
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   Answer: C. Pass water through sand or similar media

   A sand filter passes wastewater through granular media that captures remaining suspended particles.

5. Question 5

   What part of a disc filter captures suspended particles?

   1. The filter panels mounted on the discs
   2. The air diffusers below the filter tank
   3. The granular bed beneath the discs
   4. The settling zone between the discs
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   Answer: A. The filter panels mounted on the discs

   A disc filter uses filter panels mounted on rotating discs to capture suspended particles from the water.

Operator Master has 53 Level I plant operations questions, free, with an explanation after every answer.

• Math and Calculations10 questions
• Pumps and Hydraulics8 questions
• Secondary Clarification5 questions
• Biological Treatment4 questions
• Headworks and Screening4 questions
• Grit Removal2 questions
• Laboratory2 questions
• Primary Treatment2 questions