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A high rate fibre filter was used as a pre-treatment to seawater reverse osmosis (SWRO) to reduce membrane fouling. Seawater was drawn from Chowder Bay where the Sydney Institute of Marine Science, Australia is located. A lab-scale fibre filter with a height of 1000 mm and a diameter of 30 mm was used in conjunction with inline coagulation. The effect of operating the fibre filter with different packing densities (105, 115 kg/m 3) and filtration velocities (40, 60 m/h) was investigated in terms of silt density index (SDI 10), modified fouling index (MFI), pressure drop (ΔP), turbidity and molecular weight distribution (MWD). The use of in-line coagulation improved the performance of fibre filter as measured by the MFI and SDI. Regardless of filtration velocity and packing density the MFI and SDI 10 values remained low as did the turbidity until the end of the filtration run. The MWD analysis showed the removal efficiencies of organic materials like biopolymers, fulvic acids, low MW acids for even experiments with the highest filtration velocity (60 m/h) and lowest packing density (105 kg/m 3). This pre-treatment has a small foot print as it has the capacity of operating at a very high filtration velocity.

Hybrid processes combining fibre filter with deep bed filtration process such as (i) fibre filter and sand filter, (ii) fibre filter and anthracite and (iii) fibre filter and dual media filter were investigated as pre-treatments to SWRO. Seawater was drawn from Chowder Bay, Sydney. The effect of different pretreatment hybrid systems was investigated in terms of silt density index (SDI 10), modified fouling index (MFI), headloss across the filters and reduction in turbidity and dissolved organic carbon (DOC). The in-line flocculation in fibre filter improved the performance of the pretreatment hybrid system as measured by the MFI, SDI 10 , headloss, turbidity and DOC removal. The lowest SDI 10 and MFI were found with a fibre filter operated at a filtration velocity of 40 m/h followed by dual media filter operated at a filtration velocity of 5 m/h. The lowest headloss and turbidity was found with a fibre filter operated at a filtration velocity of 40 m/hr followed by anthracite operated at a filtration velocity of 5 m/h. This system also gave an effluent with the lowest DOC of 0.64 mg/L corresponding to a removal efficiency of about 70%.