Wastewater Operator Solids Handling and Disposal Questions and Answers

Question 1

An operator is using alkaline stabilization to treat biosolids. What is the primary goal of this process?

Accepted Answer

To raise the pH to inactivate pathogens and reduce odors.

Answer

To significantly reduce the volume of the sludge by removing water.

Answer

To increase the nutrient content (nitrogen and phosphorus) for fertilizer.

Answer

To produce biogas for energy recovery.

Question 2

Which of the following is a key objective of anaerobic digestion when used for sludge stabilization?

Accepted Answer

To convert volatile solids into methane and carbon dioxide.

Answer

To increase the dissolved oxygen content of the sludge.

Answer

To sterilize the sludge using high temperatures and oxygen.

Answer

To bind heavy metals using chemical precipitation.

Question 3

A treatment plant needs to dispose of its biosolids by land application on a public park. According to EPA 40 CFR Part 503, which class of biosolids is required for this type of use?

Accepted Answer

Class A

Answer

Class C

Answer

Class B

Answer

Class AB

Question 4

An operator is deciding between two solids handling processes: thickening and dewatering. What is the primary distinction between these two processes?

Accepted Answer

Thickening reduces some free water to decrease volume but the sludge remains a liquid, while dewatering removes more water to produce a cake-like solid.

Answer

Thickening uses biological processes, while dewatering uses chemical processes.

Answer

Thickening is for primary sludge, while dewatering is for secondary sludge.

Answer

Thickening increases the pH of the sludge, while dewatering lowers it.

Question 5

During the operation of a properly functioning anaerobic digester, a significant reduction in which parameter indicates effective stabilization?

Accepted Answer

Volatile Solids

Answer

Total Suspended Solids (TSS)

Answer

Fixed Solids

Answer

Settleable Solids

Question 6

Which of the following pieces of equipment is MOST commonly used for dewatering sludge into a solid cake?

Accepted Answer

Belt Filter Press

Answer

Gravity Thickener

Answer

Dissolved Air Flotation (DAF) Unit

Answer

Grit Chamber