Document Type: Research Paper
Chem Eng Dept, Ege University
In this study, the applicability of nanofiltration (NF) membranes as a pretreatment prior to reverse osmosis (RO) in seawater desalination was investigated. The membranes used were NF270 and NF90 as the NF membranes, while the brackish water (BW) RO membrane BW30 was used as the RO membrane. In desalination tests, permeates of the NF membranes were collected and used as the feed to the BW30 membrane. The calculated permeate fluxes were 6.7 L/hm2, 11.3 L/hm2, 24.3 L/hm2, and 36.6 L/hm2 for single BW30-35 bar, NF270-30 bar + BW30-35 bar, NF90-30 bar + BW30-25 bar and NF90-30 BW30-35 bar, respectively. The calculated water recovery and rejected salt values were 51.6%, 41.4%, 24.8%, 15.4% and 98.2%, 98.2%, 96.0%, 91.0% for NF90-30 bar + BW30-35 bar, NF90-30 bar + BW30-25 bar, NF270-30 bar + BW30-35 bar and single BW30-35 bar, respectively. The qualities of the product waters of integrated systems (NF + BWRO) and the single BWRO system were also investigated. Boron rejection was fairly well with average boron rejections of 59.3% and 60.2% by NF90-30 bar + BW30-25 bar combination and NF90-30 bar + BW30-35 bar, respectively while single BW30-35 bar gave an average rejection of 49.6%. The results obtained showed that the quality of product water obtained using single BWRO did not comply with the irrigation standards, while the integrated systems provided total compliance to irrigation standards with the exception of boron.