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Researchers at Michigan Technological University are on to a simple, low cost solution to the complicated problem of keeping antibiotics out of water supplies. In a study of vetiver grass grown in antibiotic-laden water, they found that 95.5% of the drugs were removed from the water and taken into the plant tissue.
Vetiver grass is sturdy, spiky grass native to India that is well known for its use in erosion control. Vetiver grass is also used in perfumes and in handicrafts for local economic development projects. In a somewhat ironic twist given its aromatic properties, vetiver grass is also an up-and-comer in the growing field of phytoremediation, in which plants and wetlands are used to remove contaminants from wastewater and stormwater.
Antibiotics are part of a growing problem with pharmaceuticals in drinking water, both for human and animal consumption as well as crop irrigation. The buildup of antibiotics in the environment could encourage drug-resistant strains of bacteria to develop. Wastewater that passes through a treatment plant can still contain antibiotics, because conventional treatment methods do not break down excreted antibiotics.
In the Michigan Tech experiment, researchers grew vetiver grass under controlled conditions in a greenhouse, using a hydroponic system. Over a twelve-week period they exposed the grass to different concentrations of two antibiotics commonly used in the dairy industry, tetracycline and monensin. The results: the plants took up all of the tetracycline and all but .5% of the monensin. The researchers also noted that the plants seemed to enjoy the antibiotic bath and grew significantly faster than those in a control group. The next step is to figure out what to do with the antibiotics after they take up residence in the plant tissue.
Phytoremediation is one of those sustainability threefers we love so much. The basic concept is to use plants, often in constructed wetlands, to suck pollutants out of water. The plants provide a low cost, energy efficient way to tackle pollution, they form a wildlife habitat or potential recreation area, and they could also be harvested for other uses — as a source of non-food crops for biofuels, for example. But wait, there’s more. Phytoremediation also fits right into the U.S. EPA’s ambitious plan to create more green jobs by reclaiming brownfields for sustainable energy projects. Though a non-native species, vetiver is easily controlled and is not considered invasive, so don’t be surprised to see a big place for it in the sustainability toolkit of the future.
Image: Vetiver grass by treesftf on flickr.com.
Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. You can also follow her on Twitter @TinaMCasey and Google+.