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Replacements of existing Ultrafiltration (UF) Membranes


Replacement or Retrofitting UF Membranes are the best method to enhance the overall life of the UF system already installed, while avoiding further CAPEX costs, using existing pumps, valves, piping and skids, thereby providing a very attractive value proposition. In most cases, with proper operation and maintenance of the UF system, there are a wide range of cases where, with successive replacements of Theway UF Membranes, UF systems have run successfully for over 15 years.


File Photo of an example of replacement of existing UF Membranes with exactly equivalent Theway Membranes


Replacements of UF Membranes, while attractive, require extra effort from the owner/operator to ensure a successful replacement –


1. Feed Quality – Replacements of UF Membranes take place, in general, from 1 to 5 years from the installation of membranes. This varies with duty cycle, feed quality, cleaning frequency, effectiveness and a wide range of other parameters. Generally, the worse the feed quality, the shorter should be the filtration cycle and lesser the filtration flux, more frequent the backwash cycle and longer the backwash time, backwash flux. Even flushing and air scouring cycles are to be tweaked to suit the feed water quality.


Apart from these general guidelines, it is very important to note the current feed water quality, as compared to the feed water quality, during the installation of the previous UF membranes a few years back. If there is a change in parameters, it is imperative to work with the UF Membrane manufacturer to render a MEPSOR Projection (A Membrane Projection Software Report), which shall help in deciding the fluxes, cycle times and the frequencies of the UF system. In many cases, failure to take note of these changes in feed water quality is the main reason for problems during replacement. What we need to understand is, if these conditions could have affected the previously installed membranes, then they can affect the newly installed replacement membranes too.




2. Pump Condition – As the driving force for the Ultrafiltration process, the UF feed pump should be in proper operating condition, without rust and leakage, and able to develop the required pressure at the required flow rate. For more details of pump selection of your UF Membranes, refer here - https://www.thewaymembranes.com/post/choosing-the-right-pump-for-your-ultrafiltration-membranes





3. Valve Condition – Valves generally tend to degrade with time. It is important to ensure good health of each component of the valves related to the UF system, since this can affect the flow rate and pressure values of the whole process. If this is not ensured, no matter how many times we replace membranes, we will run into trouble with each attempt.





4. Piping Condition – Piping needs to be clean, without plaque and biomass build up in the inner walls. It is also important to check once again pipe sizing to ensure that the sizing is sufficient for the required flow rate.




5. Programming and Automation Condition – Sensors and instruments in a UF System require periodic maintenance and recalibration. When this is not ensured, the system may be operating in a condition different from what is being seen/reported by the instruments, which may have substantial impact on the health and life of UF membranes. Further, the automation should also be operating as designed in the form of appropriate signals and feedback loops to the PLC/SCADA system to and from the instruments and actuators at the UF system.




6. CEB and CIP System Conditions – Proper Dosage of cleaning chemicals at regular intervals in required quantities have to be made with chemicals of acceptable quality and purity. This is to be ensured to maintain good condition of the modules. Dosing pumps, tanks and piping have to be in proper condition.



7. Tank Conditions – Tank cleaning is laborious and cumbersome, but is mandatory for a for healthy UF operation. Unclean tanks can adversely affect feed water quality, thereby affecting membranes. Also, an unclean backwash tank will keep providing you with TSS/Turbidity in permeate in the following cycle, even if your membrane is healthy.





8. Pretreatment Conditions – The most important aspect to take care in a UF plant are the pretreatment conditions for a UF system. One must keep in mind that UF membranes are meant to treat and remove sub-micronic particles i.e. particulates of size less than 0.1 microns, even as low as 0.02 microns. Allowing particles bigger than 5 microns is not prudent and should be removed from the feed stream using pretreatment systems including PSFs, ACFs, Disc Filters, Cartridge Filters, Basket filters etc. With sufficient pretreatment UF can run for many years, when coupled with proper operating parameters.


State of Mind Requirements


We must have the following viewpoint when we go for replacements of UF membranes -

1. Existing UF Membranes – Existing UF membranes might have aged or might have been damaged due to any of the above listed reasons. It is important to realize which one of the reasons was responsible for the need for replacement.


2. Startup of UF System after replacement – When new replacement membranes have been installed into your system. It is very important to start the UF system, like it is a new system. Start it with all the precautions in the Theway UF Operation manual. For example – Start with 20% flow rate setting, Start at 50% of pressure setting and move upwards.


3. Costly Lessons – With UF membranes, mistakes are generally costly, since even small breakages in the membrane can start affecting your product water quality. UF membranes are sophisticated but sensitive and need to be handled with proper care. It is imperative to ensure that all of the above problems are taken care of.


Theway offers replacements for a wide range of popular UF membranes including UF membranes from Hydranautics, Dupont, Inge, Hyflux, Pentair, Suez, GE, IMT etc.

Please visit here to know more - https://www.thewaymembranes.com/direct-retrofit



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