New method of RO membrane Cleaning
Published on by Nikolay Voutchkov, Water Globe Consulting, LLC - President
Taxonomy
- Water
- Reverse Osmosis
2 Comments
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Hi Anthony: I agree with your comments and observations based on my personal experience with the system.
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Hi Nikolay, thanks for the link. Yeah, the DHP guys have been pushing this for some time (actually suspect they are on commision or something). I really like this concept, there's sometihng to be said for a very well engineered solution. There is no doubt this works very well and if it is employed as a regular maintenance clean, it should significantly extend membrane life. However I underrstand that it isn't effective to solve problem cases (ie. it isn't able to clean a horribly fouled membrane). Once the membrane gets to badly fouled it will have limited effect. I have seen the results of some large scale trials on this, and showed positive results. We went down the path of purchasing licences etc, and designing this into our plants. But the patent costs were simply prohibitively large. As the licences were charged on basis "per plant", smaller to mediaum sized plants are at disadvantage. In a way I see this as compensating for ineffective pre-treatment. That is, this works very well on suspended solids fouling (which is easily prevented by membrane pre-treatment). But one strength this CIP method has, is with regular application, I imagine this is effective at controlling biofouling. Both, the osmotic shock should knock the bacteria around and therefore impede growth, and also it should help lift off deposited accumulating bacteria cells before they reach the stage where they begin producing EPS (when the DP problem occurs). Typically with bio, there is a grace period from plant start up of 2 - 3 months, while the cells accumulate on the membrane (but don't yet cause DP increase - operator is blisfully unaware), before the cells start producing EPS resulting in the DP increase. With regular application ofthe DOHS CIP, the accumulation ofthe cells can be managed before they reach the critical mass. Cheers, Anthony