Successfully Operating a Seawater UF Pretreatment System

Abstract

To overcome problems of high silt density index (SDI) and reverse osmosis (RO) feedwater turbidity in its Phase A plant, Kindasa Water Services, Jeddah, Saudi Arabia, introduced ultrafiltration (UF) in the pretreatment system of its Phase B1 expansion. Based on pilot trials of the UF plant, it was decided to include high-rate dual-media filters upstream of UF to make the pretreatment system more reliable. Commissioned in August 2006, the plant's pretreatment system was able to achieve SDI of less than 1.0 and turbidity of less than 0.2 ntu. Raw seawater SDI was not measurable, and turbidity was greater than 10 ntu. Although the UF system's performance was satisfactory, the plant experienced UF fiber damage, lower UF recovery because of high consumption of flushing water, biofouling in RO membranes, and mechanical damage of UF components. Remedial measures were adopted to overcome those problems.