What indicator is used for assessing clarifier stability?

The Sludge Volume Index (SVI) is a crucial indicator used to assess clarifier stability in wastewater treatment processes. It provides a measure of the settleability of the activated sludge in a clarifier. SVI is determined by measuring the volume of settled sludge after a specified time and relating it to the concentration of sludge in suspension.

A low SVI indicates that the sludge is compact and has good settleability, which is ideal for clarifier performance. Conversely, a high SVI suggests that the sludge is flocculating poorly and may lead to problems such as carryover of solids into the effluent, reduced treatment efficiency, and potential compliance issues with discharge limits.

Using SVI allows operators to monitor and control the conditions within the activated sludge process to ensure the system operates efficiently, maintain proper sludge density, and enhance the overall stability of the clarifier. Thus, it serves as a direct correlation to the settling characteristics of the sludge, making it the most relevant parameter among the options provided for assessing clarifier stability.