El Guapo's post reminded me of this one I saw mentioned in Goverment Technology magazine....not really a similar story...but interesting nonetheless.
Feeding Old Beer to Hungry Bacteria May Help Clean Up Superfund Site
Imagine: hundreds of gallons of old beer being dumped while billions of hungry bacteria just wait for some stimulating brew to fuel a chemical reaction that can contain the pollutants in Oklahoma's Tar Creek, one of the nation's most contaminated sites.
University of Tulsa chemistry professor Tom Harris made the connection between the expired beer and its potential for improving the efficiency of man-made wetlands, which a governor's task force has recommended as a way of cleaning up the hazardous wastes emanating from the old zinc and lead mines in northeast Oklahoma.
Harris and TU chemistry student Crystal Redden, a Picher native who used to play on the mine tailings, are working this summer to determine how helpful old beer might be.
Redden, a sophomore, is a student in TURC (Tulsa Undergraduate Research Challenge), a program that offers highly motivated undergraduate students challenging research, advanced coursework and one-on-one mentoring with faculty. Her work is funded by TURC and through TU's Science, Mathematics, Engineering, and Technology program, which is funded by the National Science Foundation. She attended the Oklahoma School of Science and Mathematics.
Also assisting is TU biology professor William Rosche. Another TU chemistry student, Brooke Stephenson, helped lay the groundwork for the current experiments.
"We are seeking innovative but practical ways to enhance the efficiency of engineered wetlands so that they can be made smaller," explains Harris. "While wetlands accumulate the heavy metals, they must be 'cleaned out' at the end of their useful lifetime." The soil-trapped pollutants must be removed from the ground and placed in a safe place where they no longer pose a health hazard. Thus, the smaller the wetlands, the less expensive.
When groundwater seeps into the mines, it flushes out iron, zinc, lead and cadmium. In a natural wetland, bacteria can capture such heavy metals and hold them in place in the soil. However, it appears that in a matter of months the bacteria's work rate fades and ends.
"The goal is to get the mine drainage to pass through the organic matter and trap the heavy metals," says Harris.
Key players in this clean-up system are sulfate reducing bacteria -- or SRB -- that convert sulfate ions to sulfide ions, a process that precipitates or separates the iron out of the water, trapping it in the soil. Another key microorganism is the fermenting bacteria, which consume the beer. These capsule-shaped bacteria measure about one micron. This means 1,000 bacteria placed end to end could fit in a millimeter.
The SRBs use simple organic acids, such as lactic acid, as their energy source, and they use sulfate ion for respiration, converting it to sulfide. The acids are produced by the fermenting bacteria -- which the TU research team believes are consuming the carbohydrates found in the beer. The quantity of simple organic acids is the limiting factor of SRB activity.
"We believe it is the fermenting bacteria that break down the big sugar molecules from the beer into a form that the SRBs can use," says Rosche. "One organism's waste provides the other's food."
Rosche says that when the beer is added, "it almost appears that we're giving the bacteria an appetizer." He and TU biology student Karen Gaber, a junior from Tulsa, are conducting laboratory studies to try to identify specific bacteria that make the system work.
If the approach works, one could build smaller wetlands and then stimulate them periodically with an inexpensive source of organic carbon. "Initially we were going to use molasses," says Harris. "However, we then learned that a beer distributor in Tulsa disposes of hundreds of gallons of waste beer each month, so we switched to beer."
For now, Harris is using store-bought beer, but hopes beer distributors could be persuaded to donate their stale beer if he is able to construct a small-scale version of an engineered wetland in the Tar Creek area.
Experiments have been conducted using plastic flower boxes that are 2 to 3 feet long with a depth and width of about six inches. Gravel is placed on the bottom followed by a layer of mucky organic matter -- laden with SRBs and fermenting bacteria -- from the Tar Creek area.
In one study conducted by Stephenson, simulated mine drainage was slowly pumped through the gravel and soil beds, and by adding just 24 ounces of beer once a month, approximately 60 percent of the sulfate and iron was removed over several months. By contrast, a control bed that received no beer was completely inactive after only one month of operation. These initial research findings were presented in April at the American Chemical Society meeting in San Diego.
Now, Redden is retesting the addition of beer but using different types of test beds. One box has a deep layer of soil, another has a column of gravel going down the middle of the bed, and a third has a thinner layer of soil.
Redden uses a syringe to draw some liquid from inside the soil layer, and then runs samples through an ion chromatograph -- to test for sulfate -- and an atomic emission spectrometer -- to test for heavy metals. New technology involving use of microelectrodes plugged into the soil is providing additional information on the chemistry and biology within the test beds.
Tar Creek, deemed as a Superfund site by the U.S. Environmental Protection Agency, covers about 40 square miles in a limestone area, including Picher, Cardin, Quapaw, Commerce and north Miami.
According to Gov. Keating's task force report, which was issued last October, underground mining began in 1891 and ended in 1970, leaving 300 miles of tunnels, 165 tons of tailings, known as chat piles, and more than 1,300 mine shafts.
Harris says pollutants may also emanate from the chat piles, either washed out by rainwater or blown off by the wind. The chat has been used for aggregate in cement and asphalt, although the Bureau of Indian Affairs has prohibited the Quapaw and Miami tribes from selling chat found on tribal lands.
When large-scale mining stopped, Harris says, the pumping of water also ceased. As the mines filled with water, the exposed sulfide minerals were exposed to oxygen and bacteria, which caused them to dissolve, creating acid mine water. The drainage began feeding into the creek in 1979 via natural springs, boreholes, and open mine shafts. The ferrous material gives Tar Creek its orange color. In addition, the mine tailings, known as chat, which contain some lead, zinc and cadmium, remain on the surface of the ground, looking like bare hills or dunes.
The EPA says it has removed topsoil from more than 1,500 homes to reduce exposure to lead, especially among children. EPA reports that lead levels of children that had been over the limit set by the federal government have gone down from 50 to 20 percent since the topsoil removal. Additional soil and turf removal is slated for approximately 600 properties.
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* TU chemistry professor Tom Harris can be reached by e-mail at firstname.lastname@example.org and by phone at (918) 631-3090.
* TU biology professor William Rosche can be reached by e-mail at email@example.com or by phone at (918) 631-2759 or in his lab at (918) 631-2563.
* Rolf Olsen, News and Marketing Manager, The University of Tulsa; E-mail: firstname.lastname@example.org; phone: (918) 631-2653.