Cleaning leaky tanks of degreaser is a costly
problem for dry cleaning plants throughout the country. Driven by
protection of the environment and a need for more cost effective
clean-up Dr. J.F Devlin, associate professor of geology, leads a team
of researchers at the University of Kansas department of geology to
improve the efficiency of current groundwater remediation techniques.
Devlin's research focuses on permeable reactive barriers, or PRBs, which are trenches dug around contaminated areas and filled with grains of iron creating a wall that filters the groundwater. PRBs can clean chemicals found in explosives, dry cleaning solutions and insecticides, some of which are cancer causing. All can cause problems with irrigation and drinking water.
Although PRBs have been in use since 1992, little is known about the processes that govern the efficiency of them. The chemical reaction that takes place between the iron and the contaminated groundwater is one focus of the research. Devlin said the research provides information on how PRBs work and could eventually lead to a better product.
The chemical reaction between the iron and contaminants was poorly
understood in large part because no one knew how to identify the
different mechanisms. Devlin describes the reaction like a fast food
restaurant in which there are three parts: production of the cooks,
production of the people working the registers and the number of
registers open. Studying the efficiency of the registers and the number
of registers open separately had never been done until Devlin started
his work. Devlin said that by separating the two aspects of the
reaction he has a much better picture of the efficiency.
Ian Bowen, one of Devlin's graduate teaching assistants, tests the chemical reactions commonly used in PRBs. Bowen lowers iron into beakers of polluted groundwater. By testing the pollution levels Bowen can measure the time it takes for harmful chemicals to react with the iron and produce new chemicals less harmful to the environment. "It gives us information on how well it works," Devlin said of the research.
Another problem facing PRBs is a need for a better understanding of flow direction of the groundwater. Pete Schillig, a doctoral student researching under Devlin, said that most failed PRBs were installed incorrectly because the installers didn't understand the flow direction. If the barrier is installed at the wrong angle, the groundwater simply flows around leaving the filter unused.
Schillig works with a mechanism called a point velocity probe that was developed by Devlin and others at the University of Waterloo to measure groundwater flow more accurately. Understanding groundwater flow helps engineers install a PRB correctly.
"We need to build a better mouse trap," Schillig said.
Fewer than 200 PRBs are installed in North America today in large part because of high installation costs. Natalie Garven, an environmental scientist, works with Devlin and at the Kansas Department of Health and Environment where she is responsible for finding the proper method of remediation for a polluted site. She said the expense of PRBs is not always worth the results.
"We don't want to make a responsible party go bankrupt," Garven said. If a company were to file for bankruptcy, the cost of remediation would be passed onto taxpayers.
The iron research done at KU could enhance other iron-using remediation methods as well as PRBs. Jeff Poyer, unit manager for the remedial section of KDHE, said it has been more popular in Northeast Kansas for businesses to make a web of wells filled with iron to keep costs down. Garven has also used a method called emulsified zero-valent iron, a method that involves injecting iron into the groundwater. "There is a lot of investing that is normally conducted before any type of remediation method is put in place," Poyer said. Poyer added that other options are often just as effective and less costly.
The research done at KU won't reveal a solution to all groundwater contamination problems, but it will help scientists like Devlin understand how to develop better remediation methods. Once researchers understand what governs the chemical reaction's efficiency they will know what variables to adjust to make a better product. Pollution clean-up is an unwanted and unbudgeted cost for chemical producing businesses, but with the help of research like Devlin's groundwater remediation can become less expensive.
Devlin's research focuses on permeable reactive barriers, or PRBs, which are trenches dug around contaminated areas and filled with grains of iron creating a wall that filters the groundwater. PRBs can clean chemicals found in explosives, dry cleaning solutions and insecticides, some of which are cancer causing. All can cause problems with irrigation and drinking water.
Although PRBs have been in use since 1992, little is known about the processes that govern the efficiency of them. The chemical reaction that takes place between the iron and the contaminated groundwater is one focus of the research. Devlin said the research provides information on how PRBs work and could eventually lead to a better product.
Ian Bowen, one of Devlin's graduate teaching assistants, tests the chemical reactions commonly used in PRBs. Bowen lowers iron into beakers of polluted groundwater. By testing the pollution levels Bowen can measure the time it takes for harmful chemicals to react with the iron and produce new chemicals less harmful to the environment. "It gives us information on how well it works," Devlin said of the research.
Another problem facing PRBs is a need for a better understanding of flow direction of the groundwater. Pete Schillig, a doctoral student researching under Devlin, said that most failed PRBs were installed incorrectly because the installers didn't understand the flow direction. If the barrier is installed at the wrong angle, the groundwater simply flows around leaving the filter unused.
Schillig works with a mechanism called a point velocity probe that was developed by Devlin and others at the University of Waterloo to measure groundwater flow more accurately. Understanding groundwater flow helps engineers install a PRB correctly.
"We need to build a better mouse trap," Schillig said.
Fewer than 200 PRBs are installed in North America today in large part because of high installation costs. Natalie Garven, an environmental scientist, works with Devlin and at the Kansas Department of Health and Environment where she is responsible for finding the proper method of remediation for a polluted site. She said the expense of PRBs is not always worth the results.
"We don't want to make a responsible party go bankrupt," Garven said. If a company were to file for bankruptcy, the cost of remediation would be passed onto taxpayers.
The iron research done at KU could enhance other iron-using remediation methods as well as PRBs. Jeff Poyer, unit manager for the remedial section of KDHE, said it has been more popular in Northeast Kansas for businesses to make a web of wells filled with iron to keep costs down. Garven has also used a method called emulsified zero-valent iron, a method that involves injecting iron into the groundwater. "There is a lot of investing that is normally conducted before any type of remediation method is put in place," Poyer said. Poyer added that other options are often just as effective and less costly.
The research done at KU won't reveal a solution to all groundwater contamination problems, but it will help scientists like Devlin understand how to develop better remediation methods. Once researchers understand what governs the chemical reaction's efficiency they will know what variables to adjust to make a better product. Pollution clean-up is an unwanted and unbudgeted cost for chemical producing businesses, but with the help of research like Devlin's groundwater remediation can become less expensive.
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