Page 283 - ro membanes

266 12. REVERSE OSMOSIS SYSTEM DESIGN AND PRETREATMENT
TABLE 12.6 Reverse Osmosis Permeate-Water Quality Seawater SourcedPersian
Gulf
Water-Quality Parameter
Temperature, C pH
Ca2þ, mg/L Mg2þ, mg/L Naþ, mg/L
Kþ, mg/L CO32, mg/L HCO3, mg/L SO42, mg/L Cl, mg/L
F, mg/L NO3, mg/L B, mg/L
Br, mg/L TDS, mg/L
Permeate-Water Quality
Persian Gulf Source Seawater Quality
18e35 6.0e7.0 570 1,600 14,100 530
4.2 155 3,300 24,650 1.5 0.00 6.3
83 45,000
Single Pass SWRO System
19e36 5.1e6.0 1.4e2.6 2.0e3.6 142e228 4.3e6.8 0.0
1.8e2.3
3.1e6.5
222e305 0.9e1.2 0.00 1.3e2.5 1.2e1.5 380e520
Split Partial
Two Pass RO System
20e37 5.1e6.0 0.6e0.8 0.9e1.3 25e45 1.5e2.2 0.0
0.6e0.9
2.1e3.2
37.5e64 0.5e0.8 0.00 0.7e1.0 0.60e0.80 70e120
The entire volume of permeate from the first pass of the Point Lisas SWRO system is further treated in a second-pass RO system to meet the final product water-quality specifica- tions. The second-pass system also consists of two stagesdeach equipped with BWRO mem- branes. The Point Lisas seawater desalination plant has the same number of first-pass and second-pass RO membrane trains.
Because of the high fouling potential of its source seawater, this two-pass/two-stage configuration has proven to be beneficial. The high-pressure pumps of the first stage are designed for 80% lower feed pressure than these of typical single-stage system, which allows to significantly reduce the fouling on the RO elements of this pass. The permeate from the first pass is treated through a second pass system and an interstage booster pump is installed to deliver the remaining 20% of the feed pressure needed to produce water similar to that in a single-pass RO. Overall, this configuration produces better water quality, higher recovery, and results in less membrane fouling than a typical single-pass system for the same source water quality.