Textile WasteWater treatment and recycle issues

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My question regarding wastewater sludge dewatering polymer issues in recycling section. We have UF followed by RO. Cationic Polymer is effecting UF. Choking its membrane and i read a articles about it some polymer escape from UF and effects RO.

Q1. What are the alternate for Cationic polymer we can use. 

Q2. RO permeability is reduced with in a week and required CIP every month. Is it true polymer can escape from UF 

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11 Answers

  1. The question is not clear. Does it mean that the polymer is added in sludge dewatering process and filtrate is subjected for UF and RO?  If the Polymer addition in correct then it goes along with sludge and does not come to the filtrate.  Please check the polymer dozing first.

     

    Prof. Rajendrakumar V Saraf virajparyawaranprashala@gmail.com

  2. This is a classic case of old meets new. 

    With everything we do, it is critically important to ask "Why?". It becomes even more important to ask why when there is a problem. In textile operations it was common to use cationic polymers to knock out color bodies and even sizing products when conventional clarifiers were used. If these materials are larger than the nominal filter size for your UF, the obvious question is "why are you still using the cat?" Have you obtained a bench size UF to see if the cat is needed? 

    Yes, most low molecular weight pDADMACs or EPI-amines will go thru the UF and they will plug the RO especially if you have some low to medium molecular weight polyacrylate contained in the wastewater or being added as an RO antifoulant. Run a particle size analyses on the feed to the UF and the filtrate from the UF. That will tell you what size particles are passing thru and the amount. 

    Remember "Why". And hope this helps.

    1 Comment

    1. We do not have resources to investigate what u r suggesting. I m observing the problem or plant parameters. Its looks like it been polymer r the reason. And also working on replacements of polymer 

      1 Comment reply

      1. Actually you do and if not the equipment you need is easy to obtain and inexpensive. You will need a turbidimeter, a vacuum aspirator for a sink, vacuum flask and a Millipore vacuum funnel. This is the very same equipment needed to run a SDI.  If you have RO's and are not running SDI's on the water going to the RO's, you are making a grave mistake. Your UF membrane will have performance specifications. Get Millipore filters of the same pore size. Then run filtration tests of the feed to the UF. Weigh the pads before use and let them dry at 150F. Time how long it takes to filter 1 liter of water. Use the before and after weights to determine how much material was filtered. Send the filter pads to a lab for analyses. That will get you started. This gets me back to my original Post. "Why?" If you have membrane equipment, why are you not tracking its performance? Having an RO and not running SDI's is asking for maintenance trouble.

  3. Dear Mr.Fawad: Here is a reply from our Hydropath Expert:

    Please see below response from Hydropath

    Hi Rashid,

     

    This does not sound exactly like the situations we have treated so far, so please forgive me if I ask more questions.

     

    As I understand from what you are saying, this is an issue caused by the polymer used in sludge dewatering. As you are talking about UF and RO, I assume that what you are saying here is that the centrate (the fluid separated in the dewatering process) is snet to be “cleaned” in the UF and RO. Is that correct? And what is happening is that some of the polymer that is added before the dewatering process (centrifuges/ belt presses) is staying in the centrate and hence going through and clogging the filtration. Is that the issue?

     

     

    I’m afraid this is not really an area we have a great deal of expertise in – our applications are prevention of struvite and reducing the polymer in the dewatering process. We might be able to help by reducing the amount of polymer used, but that tends to be about 10-20%, so I’m not sure that will have a significant effect on the life of the membranes.

     

    I’m not sure this is a problem we can help with, I’m afraid.

     

    Let me know how you want to proceed further

     

    Regards

    Rashid Faruqi

     

    A sset  I ntegrity  M anagement Specialist

    ATG-GIS Consulting

    Calgary, AB T3H 3C7

    CANADA

     

    Cell: +1.587.999.7776

     

  4. Since most membranes have a negative surface charge at neutral pH, it makes sense that cationic polymers would foul the membranes. 

    So investigating use of non-ionic or anionic polymers (together with the appropriate coagulant) is a sensible thing to do.

    1 Comment

  5. It will all come down to testing different polymers and looking at the setup. For example, are you properly relaxing the polymer and giving it time to mix and react? Are you doing daily jar testing to check the correct dosage is being used and not an excess?

  6. This is another example of the 5 P's:  Proper Planning Prevents Poor Performance.  Intimate knowledge ahead of time with regards to process chemistry has to shed light on which post-treatments are appropriate, rather than some catch-all system.  Now that your system is broken effectively, you come running to others screaming help.  Too bad. 

    Go back to the beginning and think:  Why are cationic polymers being used at the point in the process upstream of Ultra-filtration?  Why was UF chosen to begin with?  Is it worth the money to completely re-design the system and start over?  One has doubts, so, you need to examine what gets rid of any carry over of un-reacted cationic polymer upstream of the UF.  Anionic polymers as suggested by others may help, but you are also likely to end up with too much organic "goop" in the water with result being "tar babies".

    What do your membrane OEM folks have to say?  Are you going to listen to them?  Are you able to comply?  

    Have you considered simply adding an intermediate system such as a clarifier plus clearwell?

    If you could at least do the lion's share of polymer excess removal in a clarifier, you might have better results down the road.

    2 Comments

  7. Pl. contact us we have a solution through our Product: Hydroflow.we shall install at U/s of RO plant Membranes to avoid any scaling.

    ilyaskhan@atg-gis.com

    Regards,

    M.Ilyas Khan

    1 Comment

  8. Sorry about spelling-fat fingers on an iPhone. 

  9. You may want to look st alternatives to cationic polymers.  We experienced cationic polymer bonding permanently to membranes, reducing flux rates. Cationic pliymers are not recommended for certain membrane mayerisls. Check with your membrane manufacturer. 

  10. You may want to look st alternatives to cationic polymers.  We experienced cationic polymer bonding permanently to membranes, reducing flux rates. Cationic pliymers are not recommended for certain membrane mayerisls. Check with your membrane manufacturer. 

  11. Where is the Cationic Polymer currently being used?  Here’s why I ask.  You may want to look at charge neutralizing the system with a coagulant and then using an anionic polymer as your floccualant which should help protect the UF.  Cationic polymers could escape the UF but what you can do is run an acrylamide test on the UF water going to the RO to be certain. 

    2 Comments