OPERATION OF AL-BIRK SWRO PLANT WITH TOYOBO MEMBRANE INSTEAD OF DUPONT B-10 MEMBRANE

Since its start-up in 1983, lower than expected plant performance had been observed at Al-Birk SWRO plant, capacity 2270 m 3 /d. Initially, the plant was operated on two stages DuPont B-10 followed by B-9 polyamide hollow fine fiber membranes. Though the initial performance of the B-10 membrane was acceptable, but within three months of operation, due to membrane biofouling, the membrane performance dropped. A considerable drop in both salt rejection as well as plant productivity was observed. The intensity of fouling became so alarming that it necessitated frequent membrane cleaning, cartridge filter (CF) replacement, at nearly 10 days interval. To overcome the biofouling problem and in order to find a replacement to the discontinued B-10 chlorine intolerant membrane, one train in the plant was operated in one stage utilizing the chlorine tolerant Toyobo HB 9155 HFF cellulose triacetate membrane (CTA), which is also characterized by its ability to repulse the organic foulants. For comparison, the second train was kept in normal operation in two B-10 and B-9 stages. Furthermore, the Toyobo membrane is the only membrane now available as replacement of B-10 membrane without system modification. Both trains were operated under the same prevailing operating conditions. Intermittent chlorine injection (ICI)by passing 0.2 ppm Cl2 in the feed for one hour only in 24 hours of operation was applied in the operation of HB9155 membrane and chlorination/dechlorination was applied in treatment of feed to B-10 membrane. After a few months of operation, the membrane performance, as measured by permeate flow , water recovery, conductivity and ∆p, were as follows: 46 m3/hr, 28%, about 120 µs/cm and 0.2-0.35 bar for Toyobo membrane, compared to 33 m3/hr, 25% - 20%, 120 µs/cm and 0.5-1.5 bar for B-10 membrane, respectably. There was a gradual decline in Toyobo HB9155 membrane performance, which was as discovered later, due to malmanufacturing of some membrane elements due to glue failure. Toyobo membranes, however, maintained a satisfactory performance, requiring no cleaning, contrary to DuPont B-10 membrane, which showed a drastic reduction in performance in spite of biweekly cleaning. The preliminary results indicate that, in addition to the suitability of Toyobo HB 9155 membrane as replacement of B-10,without changing the pressure vessels and with only minor modification in operating conditions, it can provide the solution to this outstanding of B-10 fouling problem. This, however, is being verified by the continuing long-term SWRO plant operation.