1. What is Sludge Volume Index (SVI)?

Definition: SVI is a measurement of the settling characteristics of sludge in wastewater treatment processes.

Purpose: It helps wastewater treatment plant operators assess sludge quality and predict clarifier performance.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( SVI \) — Sludge Volume Index (mL/g)
• \( SV \) — Settled Sludge Volume (mL/L)
• \( MLSS \) — Mixed Liquor Suspended Solids (mg/L)

Explanation: The formula calculates the volume occupied by 1 gram of sludge after 30 minutes of settling.

3. Importance of SVI in Wastewater Treatment

Details: SVI values indicate sludge quality:

• 50-150 mL/g: Good settling sludge
• 150-250 mL/g: Fair settling sludge
• >250 mL/g: Poor settling (bulking sludge)

4. Using the Calculator

Tips: Enter the 30-minute settled sludge volume (mL/L) and MLSS concentration (mg/L). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical SVI range for good sludge?
A: 50-150 mL/g indicates good settling characteristics.

Q2: What causes high SVI values?
A: Filamentous bacteria growth, low dissolved oxygen, nutrient deficiency, or high F/M ratio.

Q3: How do I measure SV?
A: Fill a 1L graduated cylinder with mixed liquor, let settle for 30 minutes, and record volume of settled sludge.

Q4: What's the difference between SVI and DSVI?
A: DSVI (Diluted SVI) uses diluted sludge and is more accurate for bulking sludge.

Q5: How often should SVI be measured?
A: Daily in conventional activated sludge plants, or as process conditions change.