Sunday, 26 October 2014
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Sensing supplies

Two technologies based on Sandia National Laboratories’ microChemLab are soon expected to be checking for toxins and harmful bacteria in the USA’s water supplies.

The microChemLab is a hand-held “chemistry laboratory.” The liquid prototype was designed and built at Sandia/California, while the microChemLab that takes measurements in the gas phase was developed at Sandia/New Mexico.

Complete with the microChemLab, electronics, and sample collector, both devices weigh about 25 pounds and fit into a box the size of a small suitcase. The only external parts of the two sensor portable technologies are water collectors.

“Our goal is to place these sensors within utility water systems and use them to quickly determine if the water contains harmful bacteria and toxins,” says Wayne Einfeld, who heads the Sensor Development Focus Area within Sandia’s Water Initiative. “This on-site monitoring approach would enhance current utility monitoring systems that require water samples to be sent to laboratories for analysis, which sometimes takes days for results.”

The United States has more than 300,000 public supply water wells, 55,000 utilities, 120,000 transient systems at rest stops or campsites, and tens of millions of hydrants. Up until now, real-time, remote water quality monitoring for toxins has been very limited.

The liquid microChemLab is currently being tested at the Contra Costa, California, Water District, says Jay West, California principal investigator.

Specifically, the team is testing to determine the steps necessary to identify toxins in drinking water, as well as expanding its capabilities as an autonomous monitor.

The device is presently collecting and analysing a water sample every 30 minutes and reporting results via a real-time data link to researchers at Sandia. In the first stages of development, this technology has the potential for early detection of biological toxins and could prove to be very helpful in maintaining the integrity of the nation’s water supplies.

The California microChemLab identifies proteins by separating samples into distinct bands in seconds to minutes. Separations occur in channels as narrow as a human hair coiled onto a glass chip about the size of a small coin.

Curtis Mowry, principal investigator for the New Mexico project, says his team is seeking to develop a device that detects trihalomethanes, undesirable by-products of the chlorination process used to control the bacterial content of water. Trihalomethanes, which can form when surface water is treated with chlorine, are carcinogenic and can have adverse liver and kidney effects.

“The EPA has regulations for water utilities to monitor for trihalomethanes on a regular schedule,” Mowry says. “Currently they have to collect samples and send them to labs for analysis. They get numbers back a few days later. This is a scary thing for us as consumers. The way it’s done now, chemists may have measured high levels and there is chance someone has already consumed the water before the utility has the analysis results. Using the microChemLab will provide a way to bring the labs to the site and get results in a more timely manner.”

The microChemLab system is expected to help water utilities to limit the initial formation of trihalomethanes by functioning as a component of a process control loop.

New Mexico’s portable unit analyses a sample of water by bubbling air through it and collecting trihalomethanes from that air. The collector is heated, sending the trihalomethanes through a separation column and then over a surface acoustic wave (SAW) detector.

“The collector and the separation column can be purchased off the shelf, but the SAW detector is at the heart of the microChemLab,” Mowry says. “The goal by the end of summer is to replace the commercial separation column with a Sandia microfabricated column made using micro-fabrication technology to reduce the power needed and increase performance.”

Commercial columns are about four to five inches in diameter. Microfabricated columns will be half a square inch. They are in development and need further tuning for trihalomethanes.

The Sandia/New Mexico microChemLab uses similar concepts to the California one — collect, separate, and detect. The main difference is at the “front end” of the device, where different capabilities are needed to be able to extract gases such as trihalomethanes from the water.

“Both systems will speed the analytical process and give the utility operator better information in a shorter time period,” Einfeld says. “In addition to routine water quality monitoring, both are expected to be part of early warning systems that can help alert utility operators to intentional contamination events that might occur at vulnerable locations downstream from treatment plants.”

Sandia researcher Jay West calibrates an instrument as part of a project to determine the steps necessary to identify toxins in drinking water


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