ZwitterCo’s new approach to water reduction and treatment is as unique to the ethanol industry as the Massachusetts-based company’s name. Recognized by Fast Company as one of the world’s most innovative companies in 2024, ZwitterCo has created a novel membrane technology unlike almost anything, according to Alex Rappaport, CEO and co-founder. Rappaport built ZwitterCo from a Tufts University Lab idea into the 2023 breakthrough technology company of the year at the Global Water Summit.&nbsp;Over the past five years, the team has raised multiple rounds of capital (including a second startup round of $54.8 million), added leading experts in water treatment to its team and debuted its technology in several sectors with known water handling issues, including ethanol and biorefining.&nbsp;The company name is a direct reference to zwitterions, molecules that have unique properties allowing them to attract water while rejecting organic compounds. By harnessing those properties, ZwitterCo has been able to design and commercialize an advanced membrane technology that offers a chemistry breakthrough for treating wastewater streams. A ZwitterCo membrane, made with zwitterion-infused material, has unprecedented fouling resistance, the company says, and organic material doesn’t get stuck in the unique pore structure like it might in traditional membrane systems. It’s like the difference between a cooking pan with a normal surface versus an option with a brand-new non-stick coating, Rappaport says.&nbsp;While the company was formed with a big-picture vision of addressing water scarcity and reuse, the team’s industry-specific approach can be distilled down to a goal of providing better membrane performance and usability over time.&nbsp;“We believe if you are going to try and get plants off of the water grid, membranes have to be more scalable and sustainable,” Rappaport says.&nbsp;A plant can’t afford to use membranes if they need to be replaced every two weeks while also requiring enzymatic cleaning, he emphasizes. “We wanted to engineer a membrane that could last for years in tough environments that you could clean with generic chemicals,” Rappaport says. “We wanted to create something that could take biological or chemical treatment processes out of the equation.”The work has allowed the team to grow quickly and enter most markets that need wastewater treatment, while also helping other sectors that doubted treating certain waste streams would ever be possible.The Case for Zwitterions&nbsp; Organic fouling is the enemy of all membranes used in contaminated surface water or high-strength industrial wastewater streams. Clogs limit the lifespan and effectiveness of the pore structure or filter substrate. Membrane material made with zwitterions, however, helps to repel organic compounds like proteins, fats and oils that would normally stick to a membrane and create fouling.&nbsp;Most membranes have a certain permeability over time, Rappaport explains, with some options only lasting 20 cleaning cycles. Part of the issue is the pressure required to maintain membrane performance through fouling.&nbsp;The zwitterionic option prevents severe fouling, so the outflow remains at the right levels, helping to maintain the integrity of the filtration media longer. Less cleaning is required with fewer harsh cleaners, which helps maintain the integrity of the filtration media longer.&nbsp;“You can go from cleaning a fouled membrane every couple of days with expensive, formulated chemicals to cleaning once every week or two using generic cleaners,” Rappaport says.&nbsp;Part of the secret to the material is the electrical charge. Zwitterions have an equal number of positive and negative charges, so they act like salt to water. According to ZwitterCo, the hydrophilic property “pulls water to the membrane, actively displacing or repelling organic compounds so they cannot adhere to and foul the membrane.”&nbsp;Using the latest techniques in molecular self-assembly, the zwitterions are situated on the membrane material in a way that creates water-loving channels. Rappaport says the membranes essentially have a single layer of water molecules that act as a shield against organic compounds. While most membranes are made to control air pockets to allow water flow, the ZwitterCo approach is more about creating water highways. During filtration, water passes through the highways, while the large organics remain behind.&nbsp;To create a more durable membrane that can withstand more wastewater streams for longer periods of time, the company adds a proprietary copolymer to the zwitterions that helps prevent the molecules from wearing away. The secret sauce of ZwitterCo is somewhere in the combination of the charged particles and the copolymers.&nbsp;DCVC, an early investor in ZwitterCo, says there are several use cases for the technology. The investment firm celebrated the opening of a ZwitterCo innovation center outside of Boston in 2024, noting interest in dealing with water usage in a world with an ever-expanding population.&nbsp;“Membranes are the treatment workhorses of the water industry,” DCVC said in a statement. “You will find water treatment membranes in every Starbucks, hospital and manufacturing plant, as well as small and large municipal water and wastewater facilities. But the chemistry from which membranes are made has been essentially unchanged for decades.”&nbsp;Since opening the innovation center, ZwitterCo has been able to launch a reverse-osmosis filter product along with multiple offerings for specific industries.&nbsp;Evok Innovations, an investment entity that led a round of funding for ZwitterCo, said in a statement that its investment recognized the “interlinked challenges of decarbonization and water scarcity.”&nbsp;“The full spectrum of the energy transition, from power and next-gen fuels to mining and critical minerals, relies on clean water,” said Naynika Chaubey, partner at Evok Innovations. “The increasing unreliability of global water sources could put many of our energy systems at risk.” Chaubey also noted that the membrane technology “is critical and timely, making this investment a cornerstone of Evok’s portfolio.”Zwitterions In the Field&nbsp; In its quest to help create clean water from every source, ZwitterCo has worked with companies in power generation, dairy processing, food waste digestate, produced water, meat and poultry, bioprocessing and others. The company has clients in the refining industry in Europe and the U.S. Rappaport once spent time in the Permian Basin of West Texas, explaining the filtration tech to an engineer trying to treat shale-oil wastewater and other products.&nbsp;With Mott Corp., ZwitterCo provides waste solutions for manure and food-waste digesters, breweries and distilleries. The company has also installed the membrane solution for Brown County Organics, which operates the world’s largest manure biogas project.In the meat and poultry industry, ZwitterCo created a version of its super filtration option as an alternative to dissolved air floatation, a mechanical screening process used to treat wastewater.&nbsp;For the biofuels sector, ZwitterCo can specifically help producers lower CI scores by dealing with residual organic-laden streams like thin stillage in the ethanol industry or digestate in the renewable natural gas (RNG) space. The company’s tech can reduce impact on energy consumption, operational costs and overall CI scores, it says.&nbsp;The super filtration option offered by ZwitterCo is designed to concentrate thin stillage by more than three times, reducing the amount of water passing through the evaporators and ultimately reducing load on downstream evaporators by more than 75%.The super filtration membranes can also be used to purify food ingredients and high-value molecules to improve product quality and enable lower-CI processes. By using a membrane process to remove suspended solids, proteins and other dissolved compounds, applications such as enzyme refining or active pharmaceutical ingredient refining following fermentation or sugar purification following saccharification can yield high-quality product outputs, but with fewer unit operations and less overall energy and water usage.&nbsp;Solugen, a biotech and clean energy company creating biobased products in Texas and Minnesota through a strategic partnership with ADM, was an early adopter of ZwitterCo membrane technology.&nbsp;At its state-of-the-art biomanufacturing facility in Houston, Solugen worked with ZwitterCo to find a lower-maintenance membrane solution that allows for the reuse of enzymes. Solugen relies on a water-based chemi-enzymatic process that removes impurities from a water stream while maintaining the presence of enzymes. ZwitterCo offered Solugen a product that required four to six times less energy than traditional, open-channel membranes.&nbsp;After adopting a ZwitterCo membrane solution, Solugen was able to reduce cycle times by nearly 100%, according to the company. The plant’s maintenance requirements were reduced and cleaning of the membranes streamlined. Solugen says it uses a warm water flush, caustic wash and a water rinse to clean its membranes and restore the original clean water to roughly 95%. Its enzyme solution also isn’t compromised.Systems Approach&nbsp;&nbsp; The membrane solutions from ZwitterCo can be customized to an individual plant or process, but most are drop-in replacements for existing filtration tech. The engineering team at ZwitterCo can provide turn-key systems or work with other preferred third parties. Rappaport says the company does a lot of on-site work and is not a membrane-in-a-box supplier. ZwitterCo takes a system approach to filtration, whether at a biogas facility or a grain processing plant.&nbsp;The engineering team helps interested parties set up feasibility studies at their respective plants or explore financial options for first-time use.&nbsp;Although Solugen was the first plant that installed the tech, ZwitterCo has since worked with more than 100 facilities. The capital raised to date has helped the team expand to meet demand in an area it believes is increasingly drawing more focus: industrial water use.&nbsp;“Right now, there is a confluence of market factors working and looking at the cost of water and how much gets used,” Rappaport says.The market factors include consumer pressure, perspectives on availability and in the case of ethanol production, the push to use water as a vehicle to lower a plant’s overall CI score. Rappaport emphasizes that he is just one of many water entrepreneurs trying to tackle the issue at scale now.&nbsp;ZwitterCo is ready to save the world’s unusable water, he says. With the zwitterionic copolymer membranes, the company says it can go “where no membrane has gone before,” and that its unique name will someday be central to any discussion on water. Author: Luke Geiver&nbsp; writer@bbiinternational.com&nbsp;&nbsp; &nbsp;

2025-05-30 - Molecule-Coated Membranes (Ethanol Producer Magazine)

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With its zwitterionic copolymer membranes, ZwitterCo has a new option for producers focused on water treatment.

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