SVI (Sludge Volume Index) Calculator




The Sludge Volume Index (SVI) is a crucial parameter in wastewater treatment that measures the settleability of sludge in a given wastewater sample. It helps operators and engineers assess the effectiveness of the treatment process and make necessary adjustments to ensure the production of high-quality effluent. Calculating SVI manually can be time-consuming and complex, but with the SVI Calculator, this task becomes quick and straightforward.

This article will provide you with an overview of SVI, the formula used for its calculation, step-by-step instructions on how to use the SVI Calculator, an example calculation, frequently asked questions, and a conclusion highlighting the importance of SVI in wastewater treatment.


The Sludge Volume Index (SVI) is calculated using the following formula:


  • SVI = Sludge Volume Index (mL/g)
  • V = Volume of settled sludge (mL)
  • H = Height of the settled sludge (mm)

How to use?

Using the SVI Calculator is simple and efficient. Follow these steps:

  1. Gather Data: First, you need to collect data on the volume (V) and height (H) of the settled sludge. Make sure the units are in milliliters (mL) and millimeters (mm) respectively.
  2. Access the Calculator: Visit the SVI Calculator on your preferred platform or use specialized software if available.
  3. Enter Data: Input the values for V and H into the respective fields on the calculator.
  4. Calculate SVI: Click the “Calculate” or “Submit” button, and the calculator will provide you with the SVI value.
  5. Interpret Results: The SVI value represents the settleability of sludge. Lower SVI values indicate better settling, while higher values may signify settling problems.


Let’s go through a simple example to calculate SVI using the provided formula:

Suppose you have collected the following data from a wastewater treatment plant:

  • Volume of settled sludge (V) = 150 mL
  • Height of the settled sludge (H) = 25 mm

Using the formula:

So, the SVI for this sample of sludge is 180 mL/g.


1. What is a good SVI value?

  • A good SVI value typically falls between 50 and 150 mL/g. Values below 50 indicate excellent settleability, while values above 150 suggest settling issues.

2. Why is SVI important in wastewater treatment?

  • SVI is crucial because it helps operators assess the performance of the wastewater treatment process. It allows for adjustments to optimize treatment and ensure compliance with environmental regulations.

3. Can I calculate SVI manually?

  • Yes, you can calculate SVI manually using the formula provided earlier. However, using an SVI Calculator simplifies the process and reduces the risk of errors.


The SVI (Sludge Volume Index) Calculator is a valuable tool for wastewater treatment professionals, making the assessment of sludge settleability quick and accurate. By monitoring and optimizing SVI values, treatment plants can maintain efficient operations and ensure the production of high-quality effluent, contributing to environmental protection and public health.

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