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Hi When you say "outlet of RO plant", do you mean in the permeate ? Unless you have a major leak from feed to permeate, that won't happen. If you mean you are getting carbon at the feed to the RO, that is not uncommon. You need to backwash your carbon filters to ensure all the fines are...

Boron isn't well rejected by RO. To get really good removal, you need to raise the pH.

No reason why they can't be outside, you just need to take extra care over the instrumentation and valves - make sure everything is weather proof. I guess the other issue will be loading / unloading resin in bad weather.

Hydranautics www.membranes.com Dow filmtec www.filmtec.com Both have some good case studies, but are obviously biased towards their own membranes. Are you looking for something specific, or just a general "grounding" ?

You will achieve a better quality dosing NaOH than you will by just letting the CO2 pass through the membrane. It's just the lack of degasser means you need to dose more NaOH. The extra NaHCO3 will therefore increase the conductivity of the final water, because the membrane will reject a given...

Ok, I guess you are adding sodium hydroxide (caustic soda) to the water. This will convert CO2 to HCO3 (NaOH + CO2 =>NaHCO3). The HCO3 will be rejected by the membranes. If you can use a degasser to remove the CO2, then you will need much less NaOH. Your final permeate will be dependent on...

I really should look at the dates of the posts before replying....

From the top .... Francis is not suffering from high DP. The primary pressure has stayed the same, and the secondary pressure has increased. My guess is somebody has closed the concentrate valve. There is a good chance you have scaled the system though, if this is true. HP13 / Rommel - High...

Toyobo details can be found here ... http://199.172.235.79/cgi/nls_cgi.exe/org_detail?102

Depending on the process you are looking for, I'd also check out Ecolochem.

45mg/l ? Wow, that's a lot. Given the previous reply, I'd just use a caustic dosing set - cheaper capital and running costs, and you can get the pH to any level you choose. You may be correct about the calcite unit continuing to work, I've only one site to go on and we definitely saw a drop off...

I really don't know. The water I had experience on was a surface water, which turned limestone brown even after an RO plant. The other thing you may get is ferric hydroxide precipitation, due to local high pH's at the surface of the media. I'm a bit confused now as to what you are trying to...

It will work, but not for very long. The iron will coat the limestone, because of a boundary layer effect. This will quickly prevent further interaction between the CO2 and the media.

Permutit Boby used to do this regularly in the 70s and 80s. They would use an eductor to suck the air out of the top of a pressure vessel, causing the regeneration chemical to flow into the vessel from the bottom. The chemical flow was stopped using a level probe in the tank. When they were...