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SVI Formula:
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The Sludge Volume Index (SVI) is a measurement used in wastewater treatment to evaluate the settling characteristics of activated sludge. It represents the volume in milliliters occupied by 1 gram of suspended solids after 30 minutes of settling.
The calculator uses the SVI formula:
Where:
Explanation: The formula calculates how well sludge settles by relating the settled volume to the concentration of suspended solids.
Details: SVI is crucial for monitoring the health and performance of activated sludge processes in wastewater treatment plants. It helps operators assess sludge settleability and make operational adjustments.
Tips: Enter the settled volume in mL/L and MLSS concentration in mg/L. Both values must be positive numbers.
Q1: What is a good SVI value?
A: Typically, SVI values between 50-150 mL/g indicate good settling sludge. Values above 150 may indicate bulking sludge, while values below 50 may indicate old or dense sludge.
Q2: How is settled volume measured?
A: Settled volume is measured by allowing a 1-liter sample of mixed liquor to settle for 30 minutes in an Imhoff cone or graduated cylinder, then reading the volume of settled sludge.
Q3: What factors affect SVI?
A: SVI is affected by factors such as sludge age, food-to-microorganism ratio, temperature, pH, and the presence of filamentous organisms.
Q4: How often should SVI be measured?
A: In most wastewater treatment plants, SVI is measured daily to monitor process performance and make timely operational adjustments.
Q5: What is the difference between SVI and DSVI?
A: DSVI (Diluted Sludge Volume Index) is measured at a standardized mixed liquor suspended solids concentration, making it more comparable across different plants than SVI.