The Sludge Volume Index (SVI) in the activated sludge process is calculated as:
Choose the correct answer
Volume of sludge after 30 min settling (mL/L) divided by MLSS (mg/L) x 1000
MLSS / volume after settling
(MLSS x SRT) / HRT
Volume settled / total volume
Correct Answer
A. Volume of sludge after 30 min settling (mL/L) divided by MLSS (mg/L) x 1000
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SVI (mL/g) = [settled sludge volume (mL/L) x 1000] / MLSS (mg/L). SVI < 100: excellent settling; 100-150: good; 150-200: fair; > 200: poor (bulking sludge, filamentous growth). Used to monitor sludge settleability in activated sludge plants.
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