An engineer at the University of Massachusetts Amherst is designing a new system that keeps water purification membranes clean using safe, non-polluting nanoscale fibers to redirect and capture microbes, as well as unwanted biological and chemical matter, thus improving the lifetime filtering capacity of the membrane.
Jessica Schiffman, assistant professor of chemical engineering in the UMass Amherst College of Engineering, says using the nanofiber strips to prevent fouling and clogging of the membranes would be a high-technology improvement to what is already a widely used state-of-the-art water treatment method.
Schiffman has been awarded a one-year, $100,000 grant from the National Science Foundation’s Chemical, Bioengineering, Environmental and Transport Systems division for the research.
Schiffman says membranes, thin sheets of material that remove unwanted bacteria and other contaminants when water is pushed through them, already are in widespread use for water purification. They are used for large municipal water supplies, buildings, laboratories and hospitals. They also are very effective in purifying water supplies in underdeveloped parts of the world. “Membranes are the number one technology for cleaning water,” she says, “And they work very well when they are clean.”
Over time, however, the membranes become fouled and they are less efficient, require more energy to push the water through them and ultimately require cleaning. Schiffman says she believes she can address this fouling process by redirecting the unwanted material to strips of nano-scale fibers containing a naturally occurring “bio-glue” attached to the surface of the membrane. The biological and chemical contaminants will be trapped on the strips and these strips can also kill the microbes.
“It’s like creating an entire bowling alley on the surface of the membrane,” Schiffman says. “Water will flow freely and be purified by the pores on the membrane’s surface, aka the bowling lanes, while the fouling agents will become trapped in the gutters. By trapping the gunk in sacrificial areas, the central lanes stay clear and will allow the membranes to function well for a long time.”
Schiffman says the strips are made of nanoscale fibers created using dopamine chemistry, an organic chemical found in the body. It is a clean, non-polluting way to capture and remove unwanted contaminants from the water, she says. “One of the goals is to avoid having to use toxic chemicals to clean the membranes,” she says.
A key goal of the research will be to demonstrate that the strips can be securely adhered to the surface of the membrane allowing them to remove the contaminants while the other sections allow water through the existing pores.
Schiffman says using the nanomaterials on an existing successful technology has several advantages. It makes the membrane multifunctional and it does this by using a non-polluting cleaning material.