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  1. dfmorvan

    Introduction & Question: Antiscalant for small RO systems and question on RO membrane pressure

    Hi your recyling alternative seems legit.
  2. dfmorvan

    Introduction & Question: Antiscalant for small RO systems and question on RO membrane pressure

    Hi Regarding CO2 depletion of mixed bed for a small system the easiest way is to use a softener instead of antiscalant and to dose caustic. Other solutions exists (degassing membranes) but they will be over expensive.
  3. dfmorvan

    Demineralisation chain

    Hi Cationic resins are pretty sturdy stuff. They can swell if they see too much chlorine, but it takes some time usually and you said that the change was abrupt It would point out to some ingress of suspended matter.
  4. dfmorvan

    Looking to increase RO (reverse osmosis) output. Will these system modifications work?

    Hi Ajz To determine what you can get out of the unit, you need to provide a detailed (as much as possible) water analysis. Please add any pretreatment you may use before the RO (sand filter, decantation, softener) This will help determine the scaling potential of the feed water and we could...
  5. dfmorvan

    RO Cleaning Cycle, when to do it

    Do some flow normalization (there are spreadsheet available from membranes suppliers. When normalized flow decreases of 15% or norm pressure drop climbs 15 % it is time to clean.
  6. dfmorvan

    Mass balance of a demineralisation unit.

    Hi There will be negligible water loss thru the degasser (the water/air flows are not comparable to a cooling tower plus the water is not hot (normally)). There may be some small losses with mist generation but really not a lot, 1% would be a max. However as other have pointed out, there is...
  7. dfmorvan

    TDS high / delta p and productivity are OK

    @Laefranz For Fujiwara test check for instance http://www.membrane.unsw.edu.au/wp-content/uploads/Vis-Inspection.pdf As for rejection enhancer, I think that Kurita (ex BKGiulini) used to have some specialty for that. It should be some tannin containing formulation that "coats" or adsorbs on...
  8. dfmorvan

    How to remove Tannin from my well water

    Hi Yes, it sort of confirms my first impression. Your water is not very hard (50 ppm as CaCO3) and so a combination of anionic resin and softening resin could give some good results. I know only of 2 Resin suppliers in India Ion exchange and Thermax, but for a small application like this you'll...
  9. dfmorvan

    How to remove Tannin from my well water

    Hi Sujith It is difficult to give an precise opinion with so little data. Do you have some more water analysis ? By which method did the WT company remove the iron? As for resin causing irritation, it depends on what you are regenerating the resin with. If you use salt to regenerate a softener...
  10. dfmorvan

    How to remove Tannin from my well water

    Hi Sujith there are specialized resins for tannin removal. They are usually weak base resins and can be cleaned quite efficiently. Look up for "organic scavenger resin", some manufacturers have specialized ion exchange resins to do that which can be regenerated with salt insted of caustic soda...
  11. dfmorvan

    TDS high / delta p and productivity are OK

    It is true that the symptoms can lead to think about membrane oxidation, so you can do a fujiwara test to check for membrane oxidation. There are some chemical treatments to try to get some rejection back, mainly based on Tannin molecule (from memory). I have never tried them so I cannot comment...
  12. dfmorvan

    Chlorine dioxide - RO membranes - CEDI

    As for the resins, cationic resin will be OK as long as the concentration is not too high. I'm more reserved about anionic resins as they will oxidise more easily. You risk losing some strong capacity which is important for capturing weakly ionized species as CO2, SiO2 and Boron. Thereis also...
  13. dfmorvan

    Chlorine dioxide - RO membranes - CEDI

    During the test we made in a dairy application ( reuse of "cow water" from milk evaporation condensate) we were working @ 1 ppm equivalent Cl2. I was first surprised to see that rejection was not affected. The test lasted for something like a month. So I think that a low residual can give good...
  14. dfmorvan

    Chlorine dioxide - RO membranes - CEDI

    Hi Schulgarten1 some doc http://www.membranes.com/docs/tab/TAB115.pdf
  15. dfmorvan

    total hardness

    or it may precipitate - depends widely on pH and presence of oxidants including Oxygen http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0042/0901b80380042b91.pdf?filepath=liquidseps/pdfs/noreg/609-02042.pdf&fromPage=GetDoc
  16. dfmorvan

    total hardness

    Hi H2S should be removed prior to RO.
  17. dfmorvan

    When I should specify a Solenoid dosing pump and a Motor dosing pump?

    For such small flowrates, Solenoid will give you a better value for money. You do not need high pressure, so a motor is not needed in my opinion. Prominent (as cited before) has an extended range, but for such low flowrates, Grundfos also make very good and reliable equipment that can dose down...
  18. dfmorvan

    TDS high / delta p and productivity are OK

    Hi wwtp2014 Check membrane manufacturers sites like dow or hydranautics. They provide free spreadsheets to do this. Delta P alone is not necessarily an accurate way to quantify fouling (even if generally speaking its upward variation indicates that something is wrong.) The problem is that there...
  19. dfmorvan

    TDS high / delta p and productivity are OK

    Hi Normally, cleaning, if properly done, even frequently, should not degrade the membrane salt rejection. I would encourage you to check on your procedure. It must be adapted to the nature of foulants. Also are you doing some normalization to follow the performance reduction of your unit to...
  20. dfmorvan

    Chlorine dioxide - RO membranes - CEDI

    Hi I used a pilot plant with 4" filmtech membranes in the dairy industry. Chlorine dioxyde concentration was around 1 ppm. It worked fine. I have no idea about CEDI with ClO2. regards

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