What is the Reason that the RO Membranes Weight is High After One Week Operation?

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What is the Reason that the RO Membranes Weight is High After One Week Operation?

Our RO membranes weight is high after one week operation.

What's the reason ? Also white color scaling?  Picture attached.

What weight after RO membranes put in operation? 

Help much appreciated.

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13 Answers

  2. Thanks all. I noted some point form your comments i will update soon to check. 

  4. White color deposits are caused due to Calcium and magnesium in water.

    The weight increase because of the scaling.

    You have regularly wash the membrane with Citric acid.

    Rajendrakumar V Saraf, FIE, FIWWA

    Chairman

     Viraj Envirozing India Pvt. Ltd

    21, Radhakrishna, Near SBI, Paud Road

    Pune 41038

    Tel 02015433445, 9822186763

    www.virajenvirozing.com

  6. Hello Mohsen,

    This is a question answered with multiple questions:

     

    • What is the position of this membrane in the pressure vessel? Usually scaling issues show up first in last membrane of vessel
    • Recommend checking the composition of this deposits 
    • Is this happening for all membranes or just those in certain location? Lead or rear side?
    • What is the increase in a) salt passage, b) differential pressure c) feed pressure (or reduction in flow if feed pressure constant). These three factors together give a very good clue as to the possible type of the problem.

    In general, having weight increase at this early stage is sign of very bad problems. Judging from the picture, scaling problem.

    Either something solid already present in the feed (like clay for example) or scaling are the explanations that could explain such rapid increase.

     

     check if there was an interruption in the dosing of antiscalant - it is recommended to check the obvious first.

     

    Weight of membranes after put in operation should be weight of the new membrane + slight increase because of the wetting.

    It can be easily checked by soaking a new membrane in water, then letting it drain for 30 minutes and weight.

    My feeling is that should only be half a kilo more than a bagged new membrane.Based on your answers to the above I can suggest some thing.

  8. A destructive membrane autopsy is required to confirm the fouling situation.  However, if your RO unit is not operating at low pH, scale is suspected.  If this is the case, use of an anti-scalant is suggested. 

    I am the first in the world to design a quantifiable foulant procedure for hollow fine fiber membranes.  It is called Membrane Punch Autopsy (MPA). 

  9. The weight of the membrane incresded due to deposition of salt, biofouling and dirt etc.This is depends upon inlet water quality.Membrane filtration systems operating in deposition have one influent (feed) and one effluent (filtrate) stream. These systems are also commonly called “dead-end” or “direct” filtration systems and are similar to conventional granular media filters in terms of hydraulic configuration. In deposition mode, contaminates suspended in the feed stream accumulate on the membrane surface and are held in place by hydraulic forces acting perpendicular to the membrane, forming a cake layer. Most hollow-fiber MF and UF systems operate in deposition mode. Typically, accumulated solids are removed from MF/UF systems by backwashing. However, some systems operate until accumulated solids reduce the flow and/or TMP to an unacceptable level, at which point the membrane cartridge is replaced. Some MF/UF systems utilize a periodic “backpulse” or a short interval of reverse flow (which may include air and/or addition of small doses of oxidants) designed to dislodge particles from the membrane surface without removing these solids from the system

  10. I have to agree with Sam and Walter, certainly looks like Calcium Carbonate. Do you have pretreatment such as a softener or utilizing an Anti-Scalant? What is your incoming Hardness? Concentrate/Permeate percentage? TDS volume? Sodium? Sulfates? Over all Water Chemistry? This is the kind of information needed to determine what the problem is, and how to correct it.

    1 Comment

    1. Increased weight is exxpected if ssolidss are ollecting in the filter but as terry says more information is required to determine whats happening

  11. Assume that maximum 50% of the membrane weight is now water (i.e., if the membrane weight is 36 lbs, it is now 36 + 0.5x36). 

    As for the white color, that is calcium carbonate.  To verify that, dip the membrane into acidic water (pH of 2 to 4) and observe the change in color.  If the color disappears, that is CaCO3.  

    If the membrane is scaled severely, most of the weight will come from the precipitation of scaling on the membranes.

  13. Hello. it looks like a scale problem. But from the photo judging? let analyze the residue. No changes in differential pressure and flow/product performance noted?