Question 4029 of 234 · California Wastewater Operator Exam
Which of the following is true about return activated sludge concentration compared to mixed liquor?
Exactly one answer is correct.
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Correct answer to question 4029
- D: RAS is more concentrated than mixed liquor because it comes from the clarifier underflow
Explanation
Thickening in the secondary clarifier concentrates the solids in the bottom, so RAS may be 5,000 to 10,000 mg/L versus 2,000 to 3,000 for mixed liquor.
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