Chlorinated Water and RO Membranes
Chlorinated Water and RO Membranes
(OP)
I have been told that chlorinated city water will destroy RO membranes over time. Is this correct? If so, is the damage reversible/repairable? We have a set out we are considering rejuvenating, but they had chlorinated city water run through them for about a year or roughly 300,000 gallons worth.





RE: Chlorinated Water and RO Membranes
If they are thin film composites the chlorine resistance is usually rated in terms of ppm-hours. This number is the product of free chlorine in ppm and the contact time in hours. TFC membranes are typically rated in the range of 1,000 ppm-h before irreversible degradation occurs. If the free chlorine in the city water was greater than 0.1 ppm for the year; the membranes are likely damaged.
You didn't specify which disinfectant your city is using, however, if they are using chloramines then the ppm-h rating for TFC elements is about 300,000 ppm-h.
RE: Chlorinated Water and RO Membranes
RE: Chlorinated Water and RO Membranes
RE: Chlorinated Water and RO Membranes
RE: Chlorinated Water and RO Membranes
cub3bead, maybe exchanging one bug for another? Sulfite feeds some Thiobacillus species.
RE: Chlorinated Water and RO Membranes
P.S. Even if you have a feed Cl concentration less than manifacturer's limit, depending on your concentration factor, it becomes more concentrate at the end elements and stages.
RE: Chlorinated Water and RO Membranes
To avoid this, I usually use bisulfite and monitor chlorine removal using ORP. Ac is another solution but as cub3bead said sometimes it can cause biofouling problems.