SLUDGE VOLUME INDEX – SVI
Sludge Volume Index, also known as SVI, describes how well the sludge from the aeration tank settles and compacts. It’s a common test question on the operator exam, so be sure to absorb this information before your next test, and try these practice problems on your own.
Sludge volume index ( SVI ) is fairly easy and quick to perform, and can be obtained using data from laboratory tests and a simple math formula. Once you’ve solved a few problems, you’ll get the hang of it.
In order to calculate sludge volume index ( SVI ), you will need two numbers. The first number comes from a 30-minute settleability test, where 1 liter of the mixed liquor sample from the aeration tank is poured into a container called a settleometer. The sludge is allowed to settle for 30 minutes, and the volume of the settled sludge is measured in mL/L.
The other number used in the sludge volume index ( SVI ) calculation comes from a MLSS test. It simply determines the suspended solids concentration of the sample from the aeration tank, in mg/L.
Sludge volume index ( SVI ) is calculated by dividing the settleability by the MLSS concentration. The SVI is always expressed in mL/g.
FORMULA TO CALCULATE SLUDGE VOLUME INDEX – SVI:
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When calculating the sludge volume index ( SVI ), make sure you don’t make any mistakes with the units. On math problems, it’s easy to make mistakes when you’re in a rush to complete the exam. Sometimes, the best thing to do is to slow down to ensure you don’t make any mistakes.
If you’re getting ready to take your operator certification exam, get in the habit of checking your work. At the test center, make sure to double-check your work before you submit it. You don’t want to get it wrong, simply because of a calculation error.
HELPFUL RESOURCES
If you’re looking for practice problems for wastewater math, click on the following link: Practice Problems
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