forward osmosis spiral wound module

Spiral wound modules made from flat sheet forward osmosis membranes

Spiral wound module summary

Packing density up to 600 m2/m3
Advantage suitable for large-volume applications due to high packing density and resulting small membrane footprint
Disadvantage membrane fouling is a big problem if waste water streams are not pre-treated to remove the majority of fouling agents,

 Detailed description

forward osmosis spiral wound module
image from microdyn-nadir.com

Spiral wound modules represent the most common membrane configuration in today’s water treatment industry. The reason mainly being a combination of high achievable packing density and the fact  that spiral wound modules are based on flat sheet membranes – the most common membrane form factor in today’s membrane production industry. Spiral wound modules for reverse-osmosis mediated desalination of seawater can reach packing densities as high as 1200 m2/m3 (8 inch modules from Toray). To achieve this kind of packing density, the distance between membrane layers becomes less than 1mm, and as a result spiral wound modules tend to foul very easily if waste water streams are not pretreated before entering the modules.

When it comes to spiral wound forward osmosis modules, packing densities cannot reach the same values as is the case for spiral wound reverse osmosis modules (refer to the table below for a calculation example). The reason being, that in forward osmosis processes there must be a cross flow of solutions on either side of each individual membrane layer. This requirement increases the total thickness of spacers between membrane layers and subsequently decreases the packing efficiency. Having said that, spiral wound forward osmosis membrane modules from Hydration Technology Innovations have packing densities close to 600 m2/m3. Since flat sheet membranes are currently the predominant membrane configuration in the FO membrane production industry, it is expected that spiral wound modules will constitute the bulk of upcoming FO module products for large-volume water treatment applications. For reasons similar to what was mentioned for hollow fiber FO membrane modules, usage of spiral wound FO modules for industrial water treatment is limited to applications where waste water streams contain low concentrations of fouling agents. Such applications include:

  1. Desalination
  2. Downstream waste water processing steps
Parameter Value
Membrane width 0,5m
Membrane length 20m
Thickness of individual membranes 200μm
Spacer thickness 3mm
Inner diameter of collection tube 10mm
Outer diameter of membrane roll 278mm*
Internal volume of module 0,03m3
Active area per module 9,5m2
Packing density 320

* See giandrandi.ch for an online calculation tool of  membrane roll diameter

The links below lead to information on alternative forward osmosis module design possibilities:

  1. Plate and frame forward osmosis membrane modules
  2. Tubular forward osmosis membrane modules
  3. Hollow fiber forward osmosis membrane module

9 COMMENTS

  1. Dear Zienab

    So do we 🙂 Realistically though, we will probably have to wait until late 2016 before spiral wound FO membrane elements will be commercially available. In the meantime, what kind of element size and numbers are you interested in? And what is the application?

    Cheers

    Ed

  2. Hi Sai

    What kind of FO membranes do you need? Flat sheet, hollow fibre, or tubular? And how many samples are you looking for?

    Cheers

    Ed

  3. Hi Ed
    I am student of BS chemical engineering, final semester. We need FO unit for experimentation purpose. Feed to be treated is produced water from an upstream Oil & Gas company. In my opinion plate & frame configuration should suit the said feed, however you can consider it also.
    What I need to know is dimensions, active area and price, also the date of delivery most importantly.
    Seeking for your reply.

  4. Hi Sai,

    Please check FTSH2O for commercially ready spiral CTA FO membrane in variety of dimensions.

    Cheers,

    Yurong

  5. Hi Mujahid

    Thanks for reaching out on your exiting plans. Would it be possible for you to share some additional information with regards to the questions below?

    – What is the composition of the feed water to be treated (TDS, COD, BOD, SDI, viscosity, etc)?
    – Have you given thought to the draw solution you will be using?
    – What exactly do you mean by “15 module system”?
    – Can you give me a more detailed breakdown of the feed throughput (i.e. liters/hour) and which recovery rates you are aiming for?
    – What is your budget and expected lead time?
    – Where is the system to be located and which external conditions will it be facing?

    Cheers

    Ed

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