1. What is MLVSS?

MLVSS (Mixed Liquor Volatile Suspended Solids) is a measure of the concentration of microorganisms in the activated sludge process. It represents the organic fraction of the MLSS (Mixed Liquor Suspended Solids) that can be volatilized at 550°C.

2. How Does the Calculator Work?

The calculator uses the MLVSS equation:

Where:

• \( MLSS \) — Mixed Liquor Suspended Solids (mg/L)
• \( volatile\_fraction \) — Fraction of MLSS that is volatile (dimensionless, typically 0.7-0.8 for domestic wastewater)

Explanation: The equation calculates the biologically active portion of the suspended solids in the aeration tank.

3. Importance of MLVSS Calculation

Details: MLVSS is crucial for determining the active biomass in activated sludge systems, calculating food-to-microorganism (F/M) ratios, and designing aeration tanks.

4. Using the Calculator

Tips: Enter MLSS in mg/L and volatile fraction (typically between 0.6-0.85 for most wastewater treatment plants). All values must be valid (MLSS > 0, volatile fraction between 0-1).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between MLSS and MLVSS?
A: MLSS measures all suspended solids in the mixed liquor, while MLVSS measures only the organic (volatile) portion that represents the active biomass.

Q2: What are typical MLVSS values?
A: Typical MLVSS ranges from 1500-4000 mg/L in conventional activated sludge systems, depending on the process.

Q3: How is volatile fraction determined?
A: By igniting dried MLSS at 550°C and measuring the weight loss. The volatile fraction = (weight loss) / (initial weight).

Q4: Why is MLVSS important for process control?
A: It helps determine the appropriate sludge age and food-to-microorganism ratio, which are critical for efficient treatment.

Q5: Can MLVSS be used to estimate microorganism population?
A: Yes, though it's an indirect measure. About 60-80% of MLVSS is typically active microorganisms.