Sludge Volume Index (SVI) is an extremely useful parameter tomeasure in a wastewater treatment process. In simple terms, SVI is the result of a mathematical calculation. It takes into account the 30-minute settleability test result and the activated sludge mixed liquor suspended solids (MLSS) test result to come up with a number (or index) that describes the ability of the sludge to settle and compact. SVI gives a more accurate picture of the sludge settling characteristics than settleability or MLSS alone.SVI can indicate changes occurring in the activated sludge treatment process. By trending SVI data over a period of time,
