1. What is the Sludge Volume Index (SVI)?

The Sludge Volume Index (SVI) is a measurement of the settling characteristics of sludge in wastewater treatment plants. It indicates the volume occupied by 1 gram of activated sludge after 30 minutes of settling.

2. How Does the Calculator Work?

The calculator uses the SVI equation:

Where:

• \( Settled\ Volume \) — Volume of sludge after 30 minutes settling (mL/L)
• \( MLSS \) — Mixed Liquor Suspended Solids concentration (mg/L)

Explanation: The equation calculates how many milliliters 1 gram of sludge would occupy after settling.

3. Importance of SVI Calculation

Details: SVI is crucial for monitoring activated sludge process performance. It helps assess sludge settling quality and predict potential bulking problems.

4. Using the Calculator

Tips: Enter settled volume in mL/L and MLSS in mg/L. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical SVI value?
A: Normal SVI ranges from 50-150 mL/g. Values >150 may indicate bulking, while <50 may indicate old sludge.

Q2: How is settled volume measured?
A: By allowing mixed liquor to settle in a 1-liter graduated cylinder for 30 minutes and recording the settled volume.

Q3: What affects SVI values?
A: Factors include sludge age, organic loading, dissolved oxygen levels, and presence of filamentous organisms.

Q4: What's the difference between SVI and DSVI?
A: Diluted SVI (DSVI) is measured at lower MLSS concentrations and is less affected by solids concentration.

Q5: How often should SVI be measured?
A: Daily monitoring is recommended for most activated sludge plants to detect trends early.