Solids Handling Practice Questions for Level 1 · Entry

1. Question 1

   What does a settleable-solids test determine?

   1. Oxygen used during incubation
   2. Weight retained on a filter
   3. Solids dissolved in the sample
   4. Volume settling in a set time
   Show the answer

   Answer: D. Volume settling in a set time

   A settleable-solids test uses an Imhoff cone to measure the volume of solids that settles from a wastewater sample during a specified time.

2. Question 2

   A sludge drying bed drains much more slowly than similar beds. Loading and weather are comparable, and water remains on the surface. What should the operator check first?

   1. Check filtrate drainage
   2. Add more wet sludge
   3. Raise polymer dose
   4. Stop all bed ventilation
   Show the answer

   Answer: A. Check filtrate drainage

   A restricted filtrate drainage path directly fits slow drainage and standing water. Adding sludge, changing polymer without evidence, or stopping ventilation does not correct the blocked drainage path.

3. Question 3

   Which description correctly separates sludge thickening from sludge dewatering?

   1. Thickening stabilizes organic solids, while dewatering completes biological treatment before storage
   2. Thickening separates grit from sludge, while dewatering removes scum from liquid surfaces
   3. Thickening produces the final dry solids, while dewatering adds water to make sludge easier to pump
   4. Thickening raises the solids concentration, while dewatering removes more water to produce a wet cake
   Show the answer

   Answer: D. Thickening raises the solids concentration, while dewatering removes more water to produce a wet cake

   Thickening concentrates sludge, and dewatering removes more water so the solids can form a wet cake for handling. For example, thickened sludge may still pump, while dewatered cake may move on a conveyor. A describes stabilization, B describes grit and scum removal, and C reverses the water-removal purpose.

4. Question 4

   What is the main purpose of digesting wastewater sludge before further handling?

   1. Concentrate sludge by settling solids and returning separated water to treatment.
   2. Stabilize organic solids so the sludge is less likely to decay and smell.
   3. Condition sludge with polymer so water drains faster during mechanical dewatering.
   4. Store sludge between scheduled hauling trips.
   Show the answer

   Answer: B. Stabilize organic solids so the sludge is less likely to decay and smell.

   Digestion breaks down biodegradable organic matter and makes sludge more stable and less likely to become strongly odorous. For example, stabilized sludge is less likely than raw sludge to turn putrid during later handling. A describes thickening, C describes conditioning, and D describes storage rather than digestion.

5. Question 5

   A clarifier's sludge-blanket reading rises over several rounds while the effluent is still clear. What does the trend mean?

   1. The clear-water zone is growing, so the operator should document improved settling before changing any sludge flow.
   2. The inlet flow is becoming more even, so the operator should verify the weirs and keep the sludge settings unchanged.
   3. The sludge is getting thinner, so the operator should review only the underflow concentration.
   4. Settled solids are building higher in the clarifier, so sludge removal and settling conditions need review.
   Show the answer

   Answer: D. Settled solids are building higher in the clarifier, so sludge removal and settling conditions need review.

   A rising blanket means the top of the settled-solids layer is moving upward and reducing the clear zone above it. For example, continued buildup can bring solids close enough to the weirs to leave with the effluent. A reverses the trend, B assigns it to even flow, and C mistakes blanket height for sludge concentration.

Operator Master has 8 Level 1 · Entry solids handling questions, free.

• Plant Operations54 questions
• Math and Calculations50 questions
• Laboratory13 questions
• Safety13 questions
• Biological Treatment12 questions
• Disinfection10 questions
• Pumps and Hydraulics8 questions
• Regulations and Compliance8 questions
• Primary Treatment6 questions
• Secondary Clarification5 questions
• Grit Removal4 questions
• Headworks and Screening4 questions