Investigation of organic fouling during ultrafiltration dedicated to reverse osmosis pretreatment

Abstract

Ultrafiltration (UF) membrane has been widely proposed as a pretreatment unit to reduce fouling in RO membrane. However, less attention has been paid for UF fouling study using high saline water such as brackish water or seawater. This paper presents a study of ultrafiltration fouling of organic matters dissolved in high saline water. Alginate, humic acid and protein were used as models of organic matters present in seawater. The fouling behavior was investigated by observing the adsorptive fouling (membrane-solutes interactions) and ultrafiltration fouling (membrane-solutes-solutes interactions). The results showed that organic fouling behavior of UF membrane in high saline water was different with in fresh water. The presence of salt ions in a feed containing organic matter increased adsorptive fouling (for alginate and humic acid) but it decreased adsorptive fouling for BSA. The UF fouling behavior of an organic matter in NaCl solution was the most similar with the fouling behavior demonstrated by organic matters dissolved in real seawater. Further, the fouling behavior was influenced by salt concentration, salt type and organic foulant type.