"We believe ZwitterCo technology will become a critical piece in solving the global water crisis"
As global industries face mounting pressure to reduce their environmental footprint and confront growing water scarcity, the demand for advanced water treatment technologies has never been more urgent. At the forefront of this innovation is zwitterionic membrane technology, a breakthrough in membrane science that offers unparalleled resistance to fouling and exceptional durability in even the harshest conditions. In this interview, we speak with Alex Rappaport, CEO and Co-Founder at ZwitterCo, to explore how zwitterionic membranes differ from conventional materials like PVDF and PES.
Could you briefly explain what zwitterionic membranes are and how they differ from traditional membrane materials like PVDF and PES?
Zwitterionic membranes are a revolutionary class of filtration materials that leverage zwitterions—water-loving molecules that contain both positive and negative charges—to create a highly hydrophilic and fouling-resistant surface. Unlike traditional membranes made from polymers like PVDF (polyvinylidene fluoride) or PES (polyethersulfone), which tend to foul easily and degrade in performance over time, zwitterionic membranes are inherently anti-fouling. This means they resist the accumulation of organic materials, oils, fats, proteins, and other contaminants that typically clog (or “foul”) traditional membranes.
Zwitterionic membranes are the culmination of decades of cutting-edge fouling-resistant membrane research
The result is a membrane that maintains high performance for longer, requires shorter, less frequent cleaning, and has dramatically lower maintenance costs and replacement frequency. In essence, zwitterionic membranes are the culmination of decades of cutting-edge fouling-resistant membrane research.
With global water consumption potentially growing by 160% by 2030, how do you envision zwitterionic membrane technology playing a role in addressing the increasing water scarcity?
Water scarcity is one of the defining challenges of our time, and industrial water users, who account for around 20% of freshwater withdrawals worldwide, are under growing pressure to recycle and reuse their wastewater. ZwitterCo’s technology enables the treatment and reuse of water streams that were previously considered untreatable due to heavy organic contamination. Our zwitterionic membranes provide the robustness needed to operate in the toughest process and wastewater streams, allowing customers to reclaim water from food & beverage processing, landfill leachate, digestate, and other difficult streams. As water reuse becomes a necessity rather than a luxury, our membranes empower industries to become stewards of their own water supply, elevating sustainability while protecting the bottom line. We believe this technology, along with others, will become a critical piece in solving the global water crisis.
What role do zwitterions and zwitterionic copolymers play in the overall performance of membranes? How does their molecular structure help in improving the membrane’s effectiveness?
ZwitterCo membranes can operate continuously for much longer durations without significant flux decline
At a molecular level, zwitterions create a hydration shell—a thin, tightly bound layer of water molecules at the surface of the membrane and throughout its pores—that acts like a physical barrier to organic and hydrophobic foulants. This hydration shell resists adhesion from oils, proteins, and other ‘sticky’ contaminants, effectively repelling fouling at the surface. When we incorporate zwitterionic copolymers into our membranes, we’re embedding these properties throughout the membrane, not just on the surface. This is crucial because past attempts at imparting the extreme hydrophilicity and anti-fouling characteristics of zwitterions into membranes were only able to do so at the surface, often by grafting zwitterions onto pre-formed membrane surfaces, but this resulted in membranes with excellent surface properties, but which still saw significant fouling within their pore structure. Therefore, the integration of zwitterions throughout the membrane’s surface and pores translates directly to consistent performance, more uptime, lower operating costs, and fewer disruptions in operation.
Zwitterionic membranes are said to reduce maintenance, downtime, and replacement costs. Could you elaborate on how these membranes help companies save on operational costs in the long term?
Traditional membranes often suffer from rapid fouling in streams with even small levels of organic contamination and require frequent cleaning, chemical flushes, and eventually full replacement, sometimes in a matter of months. Each cleaning cycle or replacement not only costs money but also introduces downtime, labor costs, and chemical disposal issues. ZwitterCo membranes can operate continuously for much longer durations without significant flux decline. When cleaning is required, they respond well to low-cost, mild cleanings, avoiding the need for harsh and expensive speciality chemicals. Over the lifespan of the membrane, this adds up to substantial savings in reduced chemical use, extended equipment uptime, lower labor costs, and fewer replacements.
We’re just scratching the surface of what zwitterionic chemistry can do
When improving the efficiency of an existing membrane system undergoing regular fouling challenges, like we might see in landfill leachate treatment or dairy processing, our performance improvements can lead to a 25-50% reduction in total cost of membrane operations, in addition to saving on chemicals and being more water efficient.
When implementing membrane solutions for water reuse in novel, hard-to-treat applications, our solutions are designed to produce clean water at or below the cost of municipal freshwater and sewer fees and alternative treatment options.
As zwitterionic membrane technology continues to evolve, what advancements or innovations do you foresee in membrane materials, pore sizes, or product lines over the next decade?
We’re just scratching the surface of what zwitterionic chemistry can do. From the founding of ZwitterCo, we’ve always treated the material chemistry innovation as a platform chemistry, one we knew could be expanded and adapted across different membrane classes and form factors. Today, ZwitterCo’s membranes are primarily used in water and wastewater applications with our superfiltration (SF) and reverse osmosis (RO) product lines. But soon you will see new products geared toward food and process applications where organic fouling is a major challenge and a bottleneck in plant operations.
Beyond that, we have always heavily invested in R&D, and our team is actively developing new membranes and membrane formats. So, stay on the lookout for further innovation across the membrane market.
Ultimately, our vision is to build out a complete membrane portfolio powered by the amazing characteristic of the zwitterionic chemistry, offering a toolbox of solutions for customers across industries and geographies, paving the way for economic and environmentally responsible industrial water treatment and reuse.