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

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

2. How Does the Calculator Work?

The calculator uses the SVI formula:

Where:

• \( Settled\ Volume \) — Volume of settled sludge in mL/L
• \( MLSS \) — Mixed Liquor Suspended Solids concentration in mg/L

Explanation: The equation calculates the volume in milliliters occupied by 1 gram of sludge, providing insight into sludge settling characteristics.

3. Importance of SVI Calculation

Details: SVI is crucial for monitoring activated sludge process performance. It helps operators assess sludge settleability and identify potential bulking or pin floc problems.

4. Using the Calculator

Tips: Enter the settled volume in mL/L and MLSS concentration in mg/L. Both values must be greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical SVI value?
A: Normal SVI ranges between 50-150 mL/g. Values above 150 may indicate bulking sludge, while values below 50 may indicate old sludge.

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

Q3: What affects SVI values?
A: SVI is affected by factors like sludge age, food-to-microorganism ratio, temperature, and the presence of filamentous organisms.

Q4: What does a high SVI indicate?
A: High SVI (>150 mL/g) typically indicates poor settling characteristics, often due to filamentous bulking or viscous bulking.

Q5: How often should SVI be measured?
A: In most treatment plants, SVI should be measured daily as part of routine process control monitoring.