On 14th October, Veolia announced that it would start manufacturing a non-PVDF membrane at its main production facility in Hungary in addition to continuing with its current PVDF based ZeeWeed range. Surprisingly, the polymer was not disclosed and the membrane water fraternity was bemused by the lack of detail of what polymer would be used to replace PVDF. The new polymer is described as complementary, but it is not clear whether it would be used in the ZeeWeed product design format or in a purpose-designed format optimized around its own characteristics. Also, would be it be an unsupported fiber like the ZW1000 or 1500 or a supported fiber for MBR as in the ZW500.
11 years ago this week, the Veolia business forerunner, GE Water bought the Dutch membrane specialist IMT to gain access to a PES membrane manufacturing facility, subsequently branded as the ZW700B. This diversified the PVDF portfolio and proved useful as a replacement option to other PES providers, but did not seem to displace the company’s PVDF focus. Of course, PES operates in a different format to PVDF.
The recent announcement suggests a fundamental shift in Veolia’s thinking to offer an option for gradually moving away from PVDF altogether in the long term. Presumably this will depend upon whether the EU PFAS restriction proposal gains traction and whether application dependent derogations are offered, for example to MBR. Options of different membrane polymers to replace PVDF in a potentially identical product type are known but not prevalent.
Alternatively, Veolia’s new membrane could be something totally new. A completely novel product would require approvals and a track record, together with proof of stability and longevity. Establishing these characteristics would present a significant challenge.
The timing of Veolia’s announcement is potentially fortuitous. Only three months ago, Chinese researchers published a paper which showed that PVDF membranes could shed PFAS components in response to chemical cleaning, Membrane Aging by Chemical Cleaning Drives the Overlooked Release of Per- and Polyfluoroalkyl Substances from Polyvinylidene Fluoride (PVDF) Ultrafiltration Membranes in Drinking Water Treatment | Environmental Science & Technology Letters | ACS Publications. The paper potentially provides support for the case by the EU to include PVDF as a PFAS in its restriction proposal.
It has long been recognised that polymeric membrane performance evolves. With use, fine particulates can partially obstruct pores to reduce permeability but improve removals. On the other hand, chlorine cleaning for both PVDF and PES membranes has been shown to affect membrane characteristics, changing pore size and surface properties. The studies have shown that the stability of polymeric membranes cannot be taken for granted and aging effects need to be considered for applications in which performance is critical.
A new polymeric would need to go through an extensive period of review to assess its suitability. A good place to start would be knowing what the membrane was made of. Meanwhile, ceramic membrane suppliers will be observing developments with interest and sense a growing opportunity!