(somber music) - [Narrator] In the massive coal fields of Pennsylvania, scars from the mining industry can be seen along its rivers and streams.

At its height, coal mining fueled the Industrial Revolution, but it also left behind thousands of mines that continue to pollute the environment with acid mine drainage.

- [Bill] The coal mine drainage is a challenge because so many of the operations that created the problem have gone bankrupt and aren't there anymore to deal with it.

And they've generated a pollutant source that could last for thousands of years.

- [Narrator] Penn State professors Bill Burgos and Jennifer Macalady are part of a transdisciplinary research effort to find and develop more effective remediation.

- We have a team of people that includes engineers, hydrologists, microbiologists to do this important job that we have to clean up acid mine drainage.

- The legacy of the coal mining operations has basically taken rock that was stable under a certain condition and now exposed it to air and water, leading to these reactions that produce this drainage.

- [Narrator] This is the air shaft of an abandoned underground coal mine.

The orange water coming out of the ground is highly acidic and steeped with toxic heavy metals, principally iron, aluminum, and manganese.

- What happens in coal mines is the pyrite, or the iron sulfide minerals that are associated with the coal, get oxidized to form sulfuric acid and that sulfuric acid dissolves rocks around it and gives you the iron aluminum manganese.

So we know some of the metals to look for.

The other things that we look for are things like sulfate.

We measure the pH.

We measure the alkalinity.

- So the challenge is to make acid mine drainage able to support life again.

And in order for it to support life, we have to raise the pH and we have to get metals to fall out of solution to become precipitates that we can then dispose of safely.

- [Narrator] In current treatment systems, acid mine drainage is commonly run through limestone channels to neutralize the acidity and remove heavy metals.

The problem is that the limestone becomes coated with iron particles and rendered ineffective, needing to be replaced.

But the science and engineering team may have found a biological answer near the source of acid mine drainage in a place called the kill zone.

- When you are traveling over landscapes in Pennsylvania that are affected by acid mine drainage, you often will see pretty large kill zones where there's no vegetation, there are dead trees, not much life.

But the color is often very red and that red color is actually a result of treatment.

It's the result of iron being oxidized and being immobilized in sort of what we're calling an iron mound.

What we find is a whole community of organisms that are together accomplishing this task of removing iron from solution while the pH remains low.

And that community contains a really quite beautiful assemblage of organisms that harvest light, organisms that produce oxygen, organisms that cycle iron, organisms that recycle organic matter.

What we would like to see in the future is a combination of the existing types of passive treatment in which we use natural microbial communities of the sort that are creating iron mounds.

Those communities can remove most of the iron at a low pH and so that is really a magical ability that we can use as a component of passive treatment to improve their efficiency.

- [Narrator] But even finding and getting to the many sources of pollution is going to be a challenge.

To that end, Penn State faculty and students work with stakeholder citizen groups like the Moshannon Creek Watershed Association.

- Dr. Burgos contacted us and so they came and they sampled the watershed.

It's a mix of small tributaries and then there's a number of mine discharges that are sampled as well.

So we got a chance to learn more about one of our tributaries where we felt like we needed to learn more.

- [Narrator] Looking at Moshannon Creek tributaries like the veins of a leaf, you can see the area to the west is adversely affected by acid mine drainage.

The students are working to identify where to target future cleanup efforts.

(indistinct yelling) - And what you need to do is break that leaf up into sections, measuring flow and measuring chemistry at different spots across the leaf to figure out and spatially identify where the worst pollutant sources might be coming in and then ideally if there is assistance that we can provide with helping in a Growing Greener grant for remediating some of these sources.

That's what we want to do in the future.