Ultrasonic PVDF Reduces Membrane Fouling for Efficient Water Reuse

Membranes are the gold standard for water treatment and reuse. However, membrane fouling inhibits flux, wastes energy, requires cleaning and replacement, and disables concentrate recirculation. Pure Blue Tech proposes ultrasonic PVDF transducers be embedded within membrane systems to reduce fouling. This innovation has potential to transform the economics of membrane operations and water reuse. Pure Blue Tech will develop the approach of integrating PVDF transducer into layers of the membrane system. Ultrasonic wave energy is non-intrusively applied to the operating membrane, preemptively mitigating fouling before and while it occurs by disrupting cake layer formation, organic and biological fouling, particle agglomeration, salt and silica precipitation, and concentration polarization. The goal of this new approach is to reduce attenuation, power intensity, system complexity, and costs relative to traditional attempts that used thick PZT transducers. In Phase I we will place thin, flexible PVDF transducers close to the membranes in a minimal ratio for flat-sheet crossflow cells and plate-and-frame systems. We will then design a spiral wound element configuration and calculate its technical and operational potential for the target market, Wastewater Reverse Osmosis (WWRO). WWRO is a cornerstone for water reuse. Municipal and industrial element sales in 2018 totaled about $200 million, constituting about 10% of the total membrane market. This innovation can retrofit existing or new build membrane-based water reuse systems. Our target municipal customers are city and county wastewater treatment plants with WWRO systems or plans. Our target industrial customers are plant owners and operators at companies committed to reuse, sustainability, and process improvements. For wastewater installations mat tolerate filtration and chemical cleaning cycles, the payback may be as short as one year because cleanings have multiple costs including power, downtime (production loss), labor to clean, chemical cost, cost of disposing chemicals, and shortened membrane life if the chemicals are harsh. Relative to current technologies, PVDF ultrasound has potential to eliminate or reduce the need for MF /UF pretreatment systems. If successful, the capital cost of the overall systems could be cut up to 50%. This would save tens of millions of dollars for a large municipal WWRO facility and space would be reduced by almost half. Environmentally, we recognize benefits including reduced cleaning chemicals and reduced discharge volume. Reducing fouling may enable recirculation of concentrate because membranes can withstand higher feed concentrations. Thus, this technology can minimize concentrate while generating product water that properly removes salts, organics, chemicals, and pathogens.