Fouling factors INDEX

Fouling cannot be easily assessed by only interpreting the permeate flux data. Irreversible fouling is normally used as an indicator to estimate the membrane fouling index, named hereafter, irreversible fouling factor (FR, ). This is defined as the ratio of the water permeate flux difference measured before and after NF of a HA solution to the water permeate flux measured before NF of a HA solution. 

Silt density index (SDl) is a sensitive method for determining the ability of a filter to remove colloidal particles 14). SDl (in min ) is used extensively as a criterion in minimizing fouling of reverse osmosis membranes. The lower the SDl value, the cleaner is the stream. Manufacturers of reverse osmosis membranes recommend that the stream be prefiltered so that it has an SDl factor less than 3.0. Typically 1 pm absolnte 6) filters have an SDl of about 4-5. Manufacturers of hallow fiber membrane filters claim SDI s in the range of 1.75 to 2.25. SDl measurements of effluents from the nano alumina media range from 0.5-1.0. The SDl of 32% PAC media was measured and found to be about 1.0. Turbidity as well as SDl tests have confirmed that the extent of shedding of PAC particles into effluent streams is minimal. 

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