NM Tech Researchers Study Methods to Thwart Biofouling

Snezna Rogelj and Frank Huang

by George Zamora

SOCORRO, N.M., April 10, 2007 – New Mexico Tech researchers are studying the cannibalistic nature of certain bacteria in hopes of finding new ways to prevent other bacteria species from forming “biofilms” that commonly foul up and clog filtering processes in water purification and desalination systems and facilities.

Frank Huang, associate professor in the New Mexico Tech Department of Civil and Environmental Engineering, and Snezna Rogelj, a biology professor at the research university in Socorro, are specifically focusing on applying bacterial cannibalism to mitigate the biofouling that occurs in membrane filters used to remove salt from the briny water that is routinely produced in crude oil and natural gas production.

Recent records supplied by the oil and gas industry in New Mexico show that more than 100 million barrels of produced water are generated each year in the state, with most of it being reinjected back into the same geological formations in which the fuel reserves are found.

“Lea County, New Mexico, for example disposes of roughly 70,000 acre-feet of oilfield-produced water (brine) per year — enough to sustain a city of 300,000 for a year, if it could be purified,” the Tech researchers note in a recently published technical report on their study.

“Water produced from oil and gas operations is therefore increasingly seen as a potential asset, as opposed to an environmental liability,” the researchers point out. “Even partial desalination of water for use in industry, agriculture, and recreation would dramatically decrease pressures on freshwater aquifers and provide more water for beneficial uses.”

Recurring problems with biofouling, however, invariably arise when large-scale implementation of membrane filters are used for desalinating produced waters.

“Naturally occurring bacteria tend to form complex bacterial communities, or biofilms, on the surfaces and interiors of the filters, where they build ‘houses,’ and, in short order, soon clog up the works,” Rogelj says.

Various biofilm matrices are relatively common and widespread throughout Nature, Rogelj says, and range from the slippery residue that forms a ring around bathtubs to the bacteria species responsible for tooth cavities and kidney infections.

The New Mexico Tech researchers are using a two-fold bacterial approach to alleviating the biofouling problem— developing ways of breaking down the biofilms that are already formed, and preventing the bacterial matrix from forming.

“We looked at injecting these bacterial cannibals into the biofilms to burst open the bad bacteria, but these parasites are very specific to their hosts, and you have to match them up exactly,” Huang says. “This is difficult to do, so it’s not a practical solution.”

“Now, we’re exploring the possibilities of using agents to prevent the bacteria from sticking to each other before they form the biofilms on the filters,” Rogelj adds. “Prevention is a better approach. . . . You know what they say, ‘A gram of prevention is worth a kilogram of cure.’”

Huang and Rogelj’s research study has been conducted at the laboratory scale for the past two years, but the researchers recently have garnered additional support and funding from Sandia National Laboratories and the State of New Mexico to expand the research to a “trailer-scale” operation which can be easily transported and used for field site testing and experiments.

“Whatever we come up with, it has to work all the time to be entirely reliable,” Rogelj points out, “not just on some days.”

Huang and Rogelj are joined in their research study by New Mexico Tech assistant professor of biology Scott T. Shors, and are also assisted by several Tech undergraduate and graduate students. The research is financed in large part by funding made available through the New Mexico Water Resources Research Institute.