NSF grant will help create beneficial biofilms on water purification membranes

UNIVERSITY PARK, Pa. -- A team of chemical engineers at Penn State has received a three-year, $400,000 National Science Foundation grant to help prevent biofouling of reverse osmosis (RO) membranes.

"The objective of this proposal is to develop beneficial biofilm enhanced RO membranes," said Manish Kumar, assistant professor of chemical engineering and the grant's principal investigator.

Reverse osmosis is a critical membrane technology for developing new water sources and often serves as the final barrier for removal of salts and other contaminants during water treatment. But RO membranes are susceptible to biological growth and biofouling, which occurs when thick biofilms form, causing problems with the treatment process. This increases energy consumption and contaminant passage, reducing RO's effectiveness and sustainability.

To solve this problem, the research team, which includes co-principal investigators Tom Wood, Endowed Biotechnology Chair Professor of Chemical Engineering, and Tammy Wood, postdoctoral researcher in chemical engineering, is seeking to employ metabolic engineering to reduce biofilm build up.

"Our lab found a specific gene that can dispense biofilm. We want to introduce good microorganisms (biofilms) to get rid of the bad microorganisms," Tammy Wood explained. The challenge is that we also have to control the size of the biofilm formed by the good microorganisms so they don't get too thick. Otherwise, the good biofilms will also foul the treatment system."

She said the good biofilms are designed send a signal to themselves that mediate their growth.

Kumar added that biofilms cannot be prevented, so the only option is to pit the good biofilms versus the bad. "Even if we have the strongest antibiotics available, some bacteria continue to replicate. Every 20 minutes they have a chance to alter their genetic makeup. If we kill 99 percent of bacteria, it's the 1 percent that evolves," he said.

Tammy Wood said they can measure how well their good biofilms are working by a color test. "The good bacteria are red, so we can check under a microscope and see how they compare with the bad strains," she said.

Kumar noted that if the research is successful, it would mean that RO membranes wouldn't need as much maintenance or require as much energy. He predicted that this grant will potentially have a broad range of societal impacts.

"If we can control biofilms on RO membranes, then a large majority of disinfectant and chemical usage will be eliminated and the overall power consumption of this critical water treatment technology will be minimized," Kumar said.

The good biofilms created may also be used for more diverse engineering applications, such as reducing corrosion, forming hydrogen for fuel cells, biocontrol in agriculture and patterning in microfluidic devices.

Kumar said the work has been aided by two undergraduate students by the chemical engineering department's summer Research Experience for Undergraduates Program.

"Penn State chemical engineering senior Tevin Moore and University of Oklahoma sophomore James Guerra have already built a see-through RO system that lets the team observe biofilm growth in real time."

The three-year grant is titled "Living Reverse Osmosis Membranes: Engineered Membrane Biofilms that Control Their Own Thickness, Prevent Biofouling and Degrade Contaminants."

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Last Updated July 07, 2014