RO for high COD inlet

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We are designing a RO system to be applied on treated water after MBR system. Still the water has 250 mg/l COD. The conventional programs to design RO don’t allow to design the RO systems for such high COD concentration. As someone experience on this kind of RO systems? How to design?

 

Much appreciated!

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17 Answers

  1. I have facing a problem with high silt ratio came from bore well. Before R.O pre-treatment equipment are MMF , ACF and 10 micron Filter bag housing. Can any one suggest me about the controlling of silt. 

    2 Comments

    2. For silt reduction maybe use some coagulant and ultrafiltration prior FEED INTO RO system . I had experience with creating micro pin flocs and than filtrating it with XFlow and INGe membra

      2 Comment replies

      2. Michael , Good to hear you. We have no more space , we can just coagulant dosing before MMF and After feed pump 3 inch PVC line , Otherwise have no other option due lack of space availability . Please suggest best of the best coagulant available in market. However, Our First pass R.O has 4 inch 1 micron membrane AD-90 Model  GE brand  like ultra filtration membranes , only change in Passes, First pass R.O has three passes for converting 12000 ppm to < 100 ppm TDS , PD Pump Pressure 35 Bar, Furthermore, SDI mostly After ( MMF+ACF+10 Mirco Bag filter is) above 3. 

  2. Installing a Softerwater catalytic conditioner as a pretreatment to either the PAC filtration and/or RO will reduce the electrical charge of the remaining minerals allowing the back flush operation the PAC filtration and RO membranes to be more effective increasing the usable life of filter media and membranes. Contact me for further information.

    1 Comment

  4. After MBR you ​have to use  biological activated carbon for ​RO

  5. If it is true that you have your biological system optimized, then we can say that most of the 250 mg/l COD would consist of biologically inert material.

    In that case to lower the COD to reasonable levels for RO feed would require either adsorption or (chemical) oxidation.

    I suggest you explore using powdered activated carbon (PAC) dosed in the aeration tanks. There are systems out there that can be installed along with PAC regeneration to reduce the PAC usage. Otherwise the PAC will be removed together with the WAS.

  7. Thanks very much for all your answers!

    I will try to answer all of you:

    We are dealing with industrial waste water, the aim, is to reuse the water, but more important reduce the volume of water into environment (this is an obligation!).

    It is needed to treat 4800 m3/d (200 m3/h).

    In this moment the CAPEX it is not important, the factory really need to solve the problem. ZLD will be on the table to discuss!

    The WWTP is working very well, follow the parameters: the BOD is less than 20 mg/l this is why we can’t reduce more the COD with the biological process, Nitrogen 0,90 mg/l, phosphorous 0,3 mg/l; conductivity 3800 us/cm.

    Of course the first option is to try to reduce as much as possible the organic matter before RO. But we have already the WWTP optimized, and with the best available technologies (MBR, with membranes of 0.02 µm). Activated Carbon would be an option but we have afraid for our experience that will be “clogging” often.

    This project will be quite similar to a landfill leachate, where RO is used, and we think the design could be similar! I will contact Mr Pat, for the Rochem membranes, it seems a good way. Also I would like to explore more the Mr Derya option of AFM medium.

    2 Comments

    1. Good day Cátia,

      We re-purify any kind and flow of wastewater in to potable water with 95% efficiency, just renewable, small space and very low operating costs between another advantages ensuring short period investment recovery.

      15 years experience in wastewater purification.

      Regards,

      arturo.k01@gmail.com

    2. Hi Catia

      It is not a bad idea to use CF to reduce the organics but must be careful with the type of carbon that you use, also the system (tank, diffusers, piping etc.) must be designed to be sanitized with steam, just like in the dairy industry, also the Carbon media must be replaced more frequent that usual, hard to tell now because it depends on the maintenance that the operators give to the system, best case scenario would be 12-18 months.

      I think your best bet is to use a membrane that can be sanitized with hot water such as the Hydracore 70 manufactured by Hydranautics, I’ve used those membranes to concentrate cheese whey and although they need to be cleaned every day, they do a pretty good job reducing COD from about 100,000 to less than 2000 with a concentration factor of x3, which is a 98+ % COD removal.

      However, I will recommend you to run a pilot, especially with the type of water that you are dealing with.

      I hope this help you, if you are used to a different brand of membranes, I am sure that DOW will have an equivalent to the Hydranuatics Hydracore.

      If you need more information, I will be happy to share it with you.

      Good Luck

      Luis Inarejo

  8. If you have suspended solids going into your MBR a better screen or filter would be a cheap option to reduce loading and increase your effluent quality. After the MBR if needed an AC filter is a good option but bear in mind the cost of getting the filter recharged. Minimise the loading on your RO anyway you can, less energy and less fouling.  RO will probably be your most expensive process in terms of kg nutrient removed, depending on the application and effluent quality requirements you could RO a fraction of your flow and dilute. Lots of options but I'd say start from the beginning and look for any opportunity to reduce loading.

  9. Totally different opinion here.  Traditional RO elements (not membranes) are primarily limited by the feed spacer, not the capability of the membranes.  Rochem manufactures DTRO® RO modules and systems for treating very dirty water such as landfill leachate with COD in the multiple thousands of parts per million. The membranes are cleaned every 200 or so hours and depending on the application have a typical life of 3 to 7 years. Contact me for more information

    1 Comment

  11. One activated carbon filter as pretreament and a membranes cleaning programe  is the best solution. 

  13. Hi there. What is the throughout volume? 

  16.  Hi Cátia  

    After MBR you have to use pre-treatment for RO. We are supplying  AFM filter for pre-treatment for Reverse Osmosis. It can reduce COD less than 50. We are doing test with AFM for the gelatin sewage water after conventional water treatment plant now. If you want, I can share with you  with you results after test. Also if you want to follow link you can see product and details.

    http://www.advancewater.co.uk/dryden-aqua/

    https://www.drydenaqua.com/files/water/resources/pdf/Reports/BiofoulingandPretreatmentpriortomembranesusingAFM.pdf

    for further information

    Regards 

    Derya Ertugrul

    derya@advancewater.co.uk 

     

     

  17. Put in a filter unit before MBR they are not fittet for large particles