What index is used to measure membrane fouling?

The Silt Density Index (SDI) is widely used to assess membrane fouling, particularly in water treatment processes. The SDI measures the rate at which particles in the water can clog membrane filters, providing a quantitative indicator of the potential for fouling. It is determined through a standardized test that quantifies the amount of silt present in a water sample by measuring the time it takes for a known volume of water to pass through a filter of a specific pore size. A higher SDI value indicates a greater risk of membrane fouling because more particulate matter is likely to accumulate on the membrane surface.

In contrast, while other indices exist, such as the membrane fouling ratio, filtration efficiency index, or purge efficiency index, these are not the primary metrics used to assess and predict fouling associated with membranes. The SDI is specifically tailored to focus on fine particulates and particulate fouling, making it the preferred choice in many membrane applications.