Though PES membranes are widely used for protein concentration, medical devices, and water and wastewater treatment, the inherent hydrophobic nature of PES, causing membrane fouling is their primary disadvantage. Literature shows a significant amount of research on the modification of PES membranes via a number of methods to reduce fouling and improve performance. Despite decades-long research, commercial availability of charged PES membranes is extremely limited.

Technically, the primary approaches to develop charged PES membranes are modification of the PES polymer and surface modification. Despite past presentations regarding whey protein concentration with charged membranes produced via surface modification, the long-term success of these membranes has not occurred.

ZwitterCo membranes utilize a brand new zwitterionic copolymer chemistry. Rather than a step-change to existing membrane chemistry, ZwitterCo membranes represent a leap forward with a revolutionary anti-fouling membrane chemistry that has been shown in field operation to be permanent and stable.

Please visit our innovation page on our website to learn more about the chemistry.

The graph contained data provided by our customer. On some days, data was only provided for the ZwitterCo Evolution SF membranes.

Evolution SF sanitary elements are ideal for the following applications: high-solids protein concentration, streams with high fat content, and protein concentration where NF is already being used (and lactose and ash rejection is not required).

Evolution SF replace tighter UF membranes at the back-end of a system, such as those rated as 3 kDa and 5 kDa. If the UF membranes needing to be replaced are 10kDa or greater, then Evolution PCM should be considered.

Evolution SF may replace conventional piperazine-based NF membranes, often rated from 200 Da – 800 Da MWCO. An important question to consider when replacing NF membranes is: “What else does the NF need to retain other than protein in my product?”. Evolution SF is not designed to significantly reject smaller species like lactose or minerals.

For example, in WPI production, an evaporator cannot be used to drive up the solids before drying because it will denature the protein. Instead, an approach is to use NF to remove water and drive up the solids before drying. If Evolution SF is used in this application, more lactose will pass and increase the protein even higher, resulting in a higher bulk density. Additionally, Evolution SF elements can be more simply and better cleaned than conventional NF elements, including using chlorine if needed.

The thickness of Evolution membranes are consistent with that for conventional polyester-backed membranes, so the membrane area of Evolution spirals is equivalent to conventional membrane elements.

Systems cleaned and sanitized using high temperature and high pH are mostly found in Western Europe. Specific polypropylene-backed membranes, often referred to as pHT or HpHT, are sold for these systems.

The temperature specifications for Evolution membranes are equivalent to sanitary membranes produced on polyester backing – 55°C / 131°F for continuous operation and 50°C / 122°F for cleaning. Common sanitizing chemicals such as chlorine (though not for RO) and peracetic acid are used to ensure systems are sanitized thoroughly. ZwitterCo is collaborating with customers to explore higher temperature sanitization and has ongoing research to expand the range of Evolution membranes.

Evolution SF membranes are a direct replacement for conventional membranes, and the same pumps and motors will be used when replacing NF membranes. Our experience is that Evolution SF will run at the same or lower pressure than conventional NF.

Evolution SF elements are already FDA-compliant for whey and milk processing, and FDA-compliant Evolution PCM and Evolution RO elements will be available by the end of 2025. We are pursuing additional certifications, including USDA, 3A Sanitary Standard 45-03, Halal, and Kosher for Evolution membranes. We have also begun working on European Regulation (EC) 1935/2004 for 2026.

Yes, there is a case study on our website showing this data from a US-based whey processor using Evolution RO to concentrate effluent streams.

ZwitterCo has begun pursuing European Regulation (EC) 1935/2004, with a target completion data in 2026. See question 7 (above) for further information on regulatory certifications.

A significant amount of analytical work has been performed while pursuing FDA compliance. These data confirmed that the potential constituents of the zwitterionic copolymer are present at such low levels, if at all, as to be safe to a reasonable certainty.

Evolution SF membrane elements, including their individual subcomponents, have been determined to comply fully with the Federal Food, Drug, and Cosmetic Act and applicable food additive regulations, including but not limited to 21 C.F.R. 174.5 (“General provisions applicable to indirect food additives”), when used consistent with guidelines.

Short answer: no.

Early in the webinar, we discussed two different ways to apply zwitterionic technology: ZwitterShield™ technology, which is zwitterionic chemistry bonded to existing membranes, and ZwitterCore™ technology, which represents fundamentally new membranes where the zwitterionic layer performs the entire separation (please see our innovation page for more on this).

Our membranes using ZwitterCore technology, including Evolution SF and PCM, have not been irreversibly fouled by organics in any application. For example, on the wastewater side, which is where we started with our technology, we can handle up to 5% oil in the feed and fully recover performance, which is a huge differentiator of our membranes.

In water and wastewater applications using our RO membranes with ZwitterShield technology, we have seen some irreversible fouling, which is not surprising at the RO level. Since our technology addresses organics, we have had some challenges with inorganic fouling with our RO membranes.

However, in the five installations we have running on wastewater effluent in the dairy industry using Evolution RO, we have not seen any irreversible fouling of the membrane itself. We have seen physical plugging where prefiltration was not properly in place, but that is a separate issue.

Evolution membranes have not been around long enough to fully validate this; however, we expect them to last at least two and a half years in these applications.

We expect Evolution membranes to have longer operational life than conventional membranes because cleaning chemistry is the primary cause of surface degradation of membranes. Because less aggressive cleaning is required with ZwitterCo Evolution membranes, they should last longer.

Evolution membranes represent significant value creation for food, dairy, and biotech processors. Their pricing is commensurate with that value creation and will result in a lower total cost of ownership than conventional membranes.

ZwitterCo offers both a subscription model and direct sale model to make it easy for customers to try Evolution membranes and would love to demonstrate this with a trial at your plant. Please contact us to discuss further.

Evolution SF is not designed to reject salt or lactose, so while it will retain protein, both lactose and salt will pass into the permeate. Because this will likely make disposal of the permeate an issue, desalination of salt whey is not seen as an ideal application for Evolution SF.

Since Evolution RO still has a polyamide component, the oxidizer tolerance for Evolution RO is the same as that for conventional RO. Just like conventional RO, chlorine should not be used with Evolution RO membranes.

Conversely, Evolution PCM and Evolution SF membranes are chlorine tolerant with similar guidelines as conventional PES UF membranes.

In terms of concentration sugars and other solubles, we do have an installation at a corn refiner using an SF-RO treatment train. The feed has high solids and high viscosity, and they are doing product concentration. The treatment train utilizing our membranes has performed quite well.

In terms of water recovery in general, this is a huge potential application for ZwitterCo, both in plant protein and many other applications. Our membranes can recover water that is currently being sent to wastewater, including diafiltration water, rinse water, or process water. By utilizing our membranes in these applications, plants can reduce their freshwater demand and decrease the amount of wastewater being treated. With the coming food-grade certification, we plan to pursue water reuse for process and would gladly discuss trials with any plant that is interested.

Thanks to the anti-fouling nature of the membrane, we believe we can achieve higher solids with Evolution RO versus conventional RO. While we do not have specific data on this application yet, we would happily run a trial with you at your plant to demonstrate this.

The ZwitterShield™ technology in Evolution RO membranes improves fouling resistance and cleanability; however, it does not alter the rejection properties of the polyamide barrier layer in the membrane. Thus we expect the BOD in the RO permeate to be roughly the same as what you are seeing with your conventional RO membranes.

Evolution membranes are designed to be direct replacements for conventional sanitary membranes and are designed to have the same pressure limits. Pressure is mainly a function of the spiral element construction, so our membrane chemistry does not affect those limits.

Maximum operating pressures:

• Evolution PCM: 300 psi (20 bar)
• Evolution SF: 580 psi (40 bar)
• Evolution RO: 800 psi (55 bar)