Assessment of silt density index (SDI) as fouling propensity parameter in reverse osmosis (RO) desalination systems

Desalination and Water Treatment, Volume 51, Issue 4-6, 2013, DOI:10.1080/19443994.2012.699448, pages 1091-1103
Assessment of silt density index (SDI) as fouling propensity parameter in reverse osmosis (RO) desalination systems
R.M. Rachman a, N. Ghaffour a*, F. Wali a & G.L. Amy a
a Water Desalination and Reuse Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia Phone: Tel. +966 28082180
Abstract
In spite of its limitations in predicting membrane fouling, the silt density index (SDI) is widely used in reverse osmosis systems because of its simplicity. It is important to use a reliable fouling index with good reproducibility and precision. Authors evaluate the reliability of SDI in order to understand the reasons for the low level of precision and accuracy.
Authors used a number of commercial SDI membranes and feedwater quality in their investigation. Results revealed the existence of membrane properties’ variation within manufacturers, producing a lack of accuracy in fouling risk estimation. The nature of particles during SDI filtration provides information that particle concentration and size play a significant role in SDI quantification with substantial representation given by particles with size close to membrane nominal pore size. In addition, turbidity-assisted SDI measurements along with determination of ultrafiltration permeate and clean water fouling potential, establish the indication of nonfouling-related phenomena involved on SDI measurement such as natural organic matter adsorption and hydrodynamic conditions that alters during filtration.
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