MLVSS Calculator

In wastewater treatment, Mixed Liquor Volatile Suspended Solids (MLVSS) measures the active biological mass in an aeration tank — the living microorganisms doing the actual treatment work. Enter your Mixed Liquor Volume, MLSS concentration, Volume of Settled Solids, and Settle Time into the MLVSS Calculator to get the MLVSS Concentration in mg/L. Secondary outputs include Sludge Volume Index (SVI), Volatile Fraction, and MLVSS/MLSS Ratio, with optional Flow Rate and Aeration Tank Volume for expanded process analysis.

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mg/L
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Results

MLVSS Concentration

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Sludge Volume Index (SVI)

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Volatile Fraction

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MLVSS/MLSS Ratio

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Frequently Asked Questions

What is MLVSS and why is it important in wastewater treatment?

MLVSS (Mixed Liquor Volatile Suspended Solids) represents the organic portion of suspended solids in an aeration tank. It's crucial for monitoring the biological activity and health of the activated sludge process in wastewater treatment systems.

How do I calculate MLVSS concentration?

MLVSS is typically calculated by measuring the volatile fraction of MLSS through laboratory analysis involving ignition at 550°C. The volatile portion that burns off represents the organic biomass content.

What is the difference between MLSS and MLVSS?

MLSS (Mixed Liquor Suspended Solids) includes all suspended solids, while MLVSS specifically measures only the volatile (organic) portion. MLVSS is typically 70-80% of MLSS in healthy activated sludge systems.

What is a typical MLVSS range for activated sludge systems?

Typical MLVSS concentrations range from 1,500 to 4,000 mg/L, depending on the treatment process design, loading conditions, and desired effluent quality. Higher concentrations may indicate better treatment efficiency.

How does SVI relate to MLVSS measurements?

Sludge Volume Index (SVI) measures sludge settleability and is calculated using settled volume and MLSS. It helps assess sludge quality and settling characteristics in conjunction with MLVSS data.

What factors affect MLVSS levels in aeration tanks?

MLVSS levels are influenced by organic loading rate, sludge retention time (SRT), temperature, pH, dissolved oxygen levels, and the food-to-microorganism (F/M) ratio in the system.

How often should MLVSS be monitored?

MLVSS should be monitored daily in most treatment plants to ensure optimal process control. More frequent monitoring may be needed during process upsets or when adjusting operational parameters.