Sludge Volume Calculator

Calculate Sludge Volume Index (SVI) and assess sludge settling characteristics

Settling Test Data

Settled Sludge Volume after 30 min (mL)

Cylinder Volume (mL)

MLSS Concentration (mg/L)

Return Sludge Concentration (mg/L)

Influent Flow (m3/day)

71.4 mL/g

Excellent Settling

Settled Volume25.0%

SDI (Sludge Density Index)1.400

DSVI (Diluted)71.4 mL/g

Blanket Depth25.0%

RAS Ratio77.8%

RAS Flow Rate7778 m3/day

Thickening Factor2.29x

Excellent< 80 mL/g

Good80-150 mL/g

Fair150-200 mL/g

Bulking> 200 mL/g

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MyCalcBuddy Editorial Team

This page is maintained as an educational calculator reference.

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Formula Source: Standard Mathematical References

by Various

ðŸ”„Last reviewed: May 2026

âœ“Formula checks are based on standard references and internal QA review.