Primary Treatment Practice Questions for Level 4 · Expert

1. Question 1

   A damaged clarifier baffle is increasing solids carryover. A second clarifier can carry average flow but not the afternoon peak. Equalization can hold six hours of peak flow. The repair takes four hours under the approved work plan, and the crew and parts are ready. What is the best plan?

   1. Delay the repair, keep both units online, and increase effluent monitoring through the peak.
   2. Equalize the peak, repair and verify the damaged unit, then return stored flow within capacity.
   3. Repair during average flow, raise sludge withdrawal, and send the peak directly to the sound unit.
   4. Isolate the damaged unit before the peak, send average flow to the sound unit, and bypass the excess.
   Show the answer

   Answer: B. Equalize the peak, repair and verify the damaged unit, then return stored flow within capacity.

   The four-hour repair fits within six hours of equalization. Equalizing the peak allows the known hydraulic defect to be repaired and verified without overloading the sound clarifier.

2. Question 2

   Two clarifiers normally receive 50% of plant flow each. During a four-hour sludge-pump repair, Clarifier 1 must be reduced to 30% of normal plant flow. Clarifier 2 can accept 10% more plant flow, and influent can be reduced by 10%. Which plan meets all three limits?

   1. Route 90% total as 30% to C1 and 60% to C2
   2. Keep total flow and shift 20% to Clarifier 2
   3. Reduce influent 20% and leave the flow split equal
   4. Shift all Clarifier 1 flow to Clarifier 2
   Show the answer

   Answer: A. Route 90% total as 30% to C1 and 60% to C2

3. Question 3

   Primary effluent TSS rises only during the first hour of morning flow. Blanket depth stays normal, sludge pumps meet capacity, and influent sampling shows a short surge of fine solids. A polymer trial improves capture but also increases primary-sludge mass by 25%, leaving little digester reserve. What is the best next evaluation?

   1. Make the polymer dose permanent through all daily flow periods
   2. Stop primary sludge withdrawal during the morning surge
   3. Test surge-paced feed against solids capacity
   4. Raise the blanket limit to store the fine solids
   Show the answer

   Answer: C. Test surge-paced feed against solids capacity

Operator Master has 3 Level 4 · Expert primary treatment questions, free.

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