Adoption of DAF as a pre-treatment method for desalination plants

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We are thinking of adopting dissolved air flotation (DAF) as a pre-treatment method for desalination plants. Your points of view, advice and experience about adopting DAF for desalination are welcome! 

Some of the questions I have are:

  1. Is DAF efficient for water treatment for desalination?
  2. Which kind of coagulant is preferred for seawater desalination process?
  3. Which parameters play key roles in flotation of seawater?

Please give your suggestions. 

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9 Answers

  1. Whilst I have not seen this in practice, I have noticed that in AMD desal plants in South Africa there are many fines that the plants struggle to cope with that naturally float and overload the UF. My experience suggest that a combination DAF and sedimentation approach would greatly improve the process both in AMD and seawater applications.

  2. Dear Vahid!

    DAF is very well suited as pre treatment for desalination in areas where algae blooms and similar events occur (oil spills). It will very effectively reduce the algae content to more than 90% in most cases. Often, additional membrane treatment is required anyway for small organic substances not removable by flotation, but harmful for RO.

    As others have written, iron based coagulants are best and aluminium based ones are not desired in desalination. Using polymers is effective, but must be very well considered, as they are very harmful for the RO. Many RO manufacturers require NO cationic polymer at all, because they cause strong fouling. 

    Depending on the intake water quality it might not be required to run a DAF system at all times. However, it should be running on stand-by, in order to get it started fast in case of intake water quality change. Depending on the water temperature and salinity, conventional DAF systems can be inefficient with a very high energy consumption due to thermodynamic laws (decreasing solubility of air in water). Especially in those cases, technologies like akvoFloat are superior. 

    Best regards, Johanna

    1 Comment

    1. Thanks for your valuable and comprehensive information

  3. We are testing this process now in the Unites States, in the oil and gas industry.  We have several things that we like so far, however we have had a few challenges with this technology that had to be over come for it to work effectively.  

  4. Have you considered SteelBlue technology. . This system uses a proprietary and uniquely configured arrangement of magnetic fields to alter the physical properties and energy states of water. The SteelBlue system modifies the internal energy of the entire water system, altering properties such as surface tension, disperse-ability and solvating properties of water. The net energy environment is modified driving insoluble substances to assume nano-sized dimensions. Second, these energy changes favor production of stable micro and nano bubbles. Each bubble is a region of rich, relatively negative dipole useful for sequestering positive ions like sodium while dispersing negative ions like nitrates

  5. DAF is suitable for organic material removal like algae' not for kind of treatment.

    in general you can start with kind of ferric.

  6. Hi Valid, it depends upon your water source, please contact me on pactuae@eim.ae, to understand more about the problem in order to give you the correct solution. Regards, Arshak Toufenkjian. 

  7. Hello Vahid, I would recommend Lamella clarifiers followed by gravity sand filters for pretreatment to SWRO considering the capital and operating cost involved . You can use any ferric iron-based coagulant in combination with anionic flocculants for better results.

  8. Good day!
    You have asked a very good question about the flotation of seawater - but why ??? What is the result you want by applying this method ???
         To achieve good results, we offer our method of desalination desalination, in which:
    - The output of desalinated water will be 85%, which is not achievable for reverse osmosis;
    - Energy consumption for desalination of one cubic meter is not more than 0.5 kW, which is also not feasible to reverse osmosis;
         All this without additional aeration - so my answer - aeration result for desalination - negative.
         A company DAF to think about cooperation with the new technologies.

    1 Comment

  9. 1. Yes, DAF is quite common for large-scale SWRO plants in the Gulf region

    2. PolyDADMAC-based ones quite common often with ferric chloride. Genesys International is a well known and established membrane specialty chemicals supplier that can assist

    1 Comment

    1. Good day!
      You have asked a very good question about the flotation of seawater - but why ??? What is the result you want by applying this method ???
             To achieve good results, we offer our method of desalination desalination, in which:
      - The output of desalinated water will be 85%, which is not achievable for reverse osmosis;
      - Energy consumption for desalination of one cubic meter is not more than 0.5 kW, which is also not feasible to reverse osmosis;
             All this without additional aeration - so my answer - aeration result for desalination - negative.
             A company DAF to think about cooperation with the new technologies.