Saturation time test of membrane to supply clean water using reverse osmosis with pressure stage in rejection

The tsunami in Pandeglang had resulted in high salinity of water and caused water scarcity. Furthermore, there were difficulties accessing water due to dry season in 4 sub-districts in Pandeglang in 2019. Reverse osmosis (RO) is a suitable technology to provide clean water, however, the advanced research is required to undrestand the method and determine the optimum pressure of multi-pass RO to produce clean water with a long saturation time of the membrane. The experimental research used RO multi-pass was operated in Tanjung Lame by various pressures 6-3, 6-4, and 7-4 on the first and second stage to observe the effect of flux decrease and TDS increase throughout 72 hours. Used P1 = 6 bar/P2 = 3 bar showed a better result compared to P1 = 6/P2 = 4 and P1 = 7/P2 = 4 in producing clean water. Provided clean water at 20 ppm has been done by RO multi-pass, which permeates the first stage used as a feed in the second stage. P1 = 6 bar and P2 = 3 bar give the saturation time of membrane 72-80 hour on the first stage and 72-131 hour on the second stage.