Will Bioremediation Work At Allied? Microbial Ecologist Skeptical
The U.S. Environmental Protection Agency will decide on the final cleanup plan for the Allied Paper Landfill site soon. But the City of Kalamazoo is still weighing its options. The city has been in talks with BioPath Solutions - a company that breaks down PCB waste with microbes. BioPath says the treatment would cost at least $15 million less than the EPA’s proposed plan. But the question remains - will it work?
Brace yourself for a science lesson - because you can’t really talk about PCBs without one. PCBs stands for polychlorinated biphenyls. It’s the chlorine that makes PCBs stick tight to things like soil and much harder to break down. At the Allied Paper Landfill site, those PCBs are stuck to clay and leftover paper residue from the old paper mills.
What companies like BioPath do is try to remove or neutralize the “C” in PCBs. Get rid of the chlorine and the compounds are easier to break down.
Dr. James Tiedje teaches microbial ecology at Michigan State University and has studied ways to break down PCBs for more than 20 years. He says for BioPath’s method to work, the company will first have to make sure their product can degrade these kinds of PCBs.
You see, there are more than 200 PCBs, each one with a different arrangement of chlorines. If you have, say, 50 varieties on one site, it gets complicated.
“The very nature of biology is specificity. So if you have 50 different chemicals, you have a challenge for biological enzymes because they are specific. So to have one enzyme to degrade 50 different compounds is really a challenge. And that’s what limits bioremediation of PCBs,” says Tiedje.
BioPath Solutions is currently testing their product on a PCB sample it took downriver from the Allied site. But Tiedje says even if that works, the PCB-eating microbes still have to find a way to get to the PCBs.
“And the more clay you have in a system, the more difficult it is to get that dispersion so that the pollutant and the microbe are side-by-side,” he says.
In fact, that’s one of the main reasons why the Environmental Protection Agency said this method wouldn’t be a good fit at the Allied site. The clay and paper residue are just too tightly bound to the PCBs.
Tiedje says there are a few ways companies like BioPath try to fix that. Some use a detergent to break chemical bonds, others churn up the material so it’s more likely that the PCBs and microbes will meet.
Mick Warner is the president of BioPath Solutions. He says the first step of is to basically compost the material, turning it over often. Warner says the leftover paper pulp at Allied is a lot like dead leaves - it’s rich in carbon.
“So in order to have a composting operation, you need to have one part nitrogen to 30 parts carbon. So what a municipality will often do is take leaf waste and mix it with grass clippings - cause grass clippings have a higher nitrogen component. And when you do that, then you can get this material to decompose.”
Breaking down the paper pulp makes it easier for the microbes to get to the PCBs. Then BioPath would add its product. Warner says that helps the native organisms on the site to eat the PCBs.
“So we’re not introducing microbes, we’re not introducing enzymes, but rather just allowing the bugs that are there to function the way that they would function in the absence of the contaminant,” says Warner
But the game isn’t over once native organisms reach the pollutant. They still have to survive long enough to break them down. MSU’s James Tiedje says the microbes will likely need oxygen - so the compost will have to be mixed often. If the weather gets too cold at the site, the EPA says the microbes could stop working.
So - will BioPath’s method work at the Allied Paper Landfill? Right now it’s hard to say. Warner says it will take about ten to 12 weeks for BioPath to get results back from the sample test.
Tiedje is not optimistic. He says there have been no great successes in cleaning up large sites like Allied with microbes.
“One wants to see the proof that there’s something really really different and understanding the basis for why that’s so different than the thousands of scientific papers that have studied this before,” he says.
The EPA will meet with BioPath Solutions to talk about the Allied Paper Landfill cleanup in March.