FREE Wastewater Operator Preliminary Treatment Processes Questions and Answers

Question 1

Which preliminary treatment process is primarily designed to remove large, insoluble solids such as rags, sticks, and plastics from the incoming wastewater flow?

Accepted Answer

Screening

Answer

Grit removal

Answer

Pre-aeration

Answer

Flow equalization

Question 2

An operator notices an accumulation of sand, gravel, and coffee grounds at the bottom of the grit chamber. This indicates the grit chamber is effectively performing its primary function, which is to remove:

Accepted Answer

Inorganic, heavy solids

Answer

Organic solids

Answer

Dissolved nutrients

Answer

Volatile suspended solids

Question 3

Which of the following describes the purpose of a comminutor in preliminary wastewater treatment?

Accepted Answer

To grind and shred larger solids into smaller, more manageable particles.

Answer

To increase the dissolved oxygen content of the wastewater.

Answer

To separate oil and grease from the wastewater stream.

Answer

To reduce the velocity of the wastewater for grit settling.

Question 4

A wastewater treatment plant is experiencing frequent blockages in its primary clarifiers due to large rags and debris. What preliminary treatment process is likely failing or inadequate?

Accepted Answer

Screening

Answer

Grit removal

Answer

Pre-aeration

Answer

Flow equalization

Question 5

What is the primary benefit of including pre-aeration in the preliminary treatment process, especially in older plants or those with long collection systems?

Accepted Answer

To reduce odors and help 'freshen' septic wastewater.

Answer

To promote the settling of inorganic grit.

Answer

To significantly remove dissolved organic pollutants.

Answer

To equalize fluctuations in flow rate.

Question 6

Which of the following is NOT a typical objective of preliminary treatment processes in a wastewater treatment plant?

Accepted Answer

To reduce the organic load (BOD) by a significant amount.

Answer

To protect downstream equipment from damage.

Answer

To remove abrasive inorganic solids.

Answer

To remove large floating and suspended solids.