• Membrane Journal
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• v.19 no.2
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• pp.165-171
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• 2009

This study was for the evaluation of adaptability of the fiber filter as the pre-treatment of the RO membrane through SDI (Silt Density Index) measurement. The turbidity of raw waters were $0.76{\sim}1.6$ NTU for the effluent of sewer treatment plants (STP) and $2.2{\sim}3.3$ NTU for sea waters and 100 NTU for the surface water. The turbidity of the $2^{nd}$ filtrate of the serially connected two fiber filters was $0.07{\sim}0.25$ NTU and $SDI_{15}$ was $1.4{\sim}2.8$ when the 17% PAC was dosed $10{\sim}30ppm$. Results of the turbidity and $SDI_{15}$ of the $2^{nd}$ filtrate of the fiber filter which were compared with them of the lab scale MF/UF disc filter for the same STP's effluents showed that filtrate quality were enhanced with a little on the order of two stage fiber filter>MF>UF, the difference in $SDI_{15}$ was only $0.7{\sim}1.0$. So, the filtrate of the serially connected two stage fiber filter could satisfy $SDI_{15}$ 5.0 safely which was normally required for the feed water by the RO membrane supplier and it means the serially connected two stage fiber filter could be applied as the pre-treatment process of the RO membrane.