Silt Density Index

This technical brief discusses the importance of Silt Density Index (SDI) testing in reverse osmosis (RO) systems to predict and prevent membrane fouling, particularly when producing drinking water from seawater. Maintaining a low SDI value is crucial to minimize fouling and maintain membrane performance.

Reverse Osmosis (RO) is a membrane-based filtration method commonly used to produce drinking water from seawater by removing salt and other substances. Membrane fouling is a major issue in RO systems, affecting permeate flux and product quality. The Silt Density Index (SDI) test measures the potential fouling rate of membranes by particles, bacteria, and organics in feed water. Membrane manufacturers and designers recommend keeping the 15-minute SDI value below 4.0 to minimize fouling. SDI values above 5 indicate higher plugging percentages. Graver recommends using high-efficiency melt blown filters like Stratum A or Stratum C Series to reduce SDI and protect RO membranes.

Need help?

You can find the right application or product using our Tool, or through our Chat Bot.