SOLON– You wouldn’t expect most high school seniors to spend much time at Solon’s waste water treatment plant behind Randall Park. But on a blustery Saturday morning, McKenna Cole and her father were ducking around two planter boxes attached to a vat of wastewater, making quick adjustments to her experimental filtration system.
Though Cole plans to enter her project into the Iowa State Fair and the Google Science Fair, the project she is working on isn’t your typical high school science experiment. Cole got the idea from a visit she took with her physics class to the Aragon Lab in Chicago.
Since May, Cole has been studying the process of phytoremediation and built her version of the process in July at the Solon plant. Her data, which she has been taking daily since September, shows promise to reduce the need for the chlorination process of wastewater treatment.
Insulated with Styrofoam, the two planters are stuffed full of 11 young poplar trees and their soil. Hoses pump chemically untreated wastewater filled with nitrogen and other pathogens into the planters. The water filters through the roots of the trees where microorganisms in the root-soil barrier metabolize the nitrogen and phosphates. Then, the remaining water drips into retrofitted rain gutters, and comes out nearly clean.
“I just thought this is awesome. Why isn’t this happening everywhere?” she said. “It’s just such a green alternative.”
Though her findings so far are positive, Cole’s research is just starting. Her focus is whether or not phytoremediation in the wintertime is still a viable alternative to some water filtration processes. Cole’s most important data will be gathered over the coming months.
“One of the hang ups is that they think it won’t work in the winter time,” Cole said. ““It’s a misconception that the tree is what actually doing the filtration. Since the microorganisms actually do it, it should still work even though the tree looks dead.”
In the larger picture, Cole is concerned about the amount of wastewater related pollution that Iowa sends to its streams and rivers, which ultimately ends up in the Gulf of Mexico. Currently she is working with local experts to study phytoremediation as an alternative to pricey chlorination and dechlorination processes.
“I couldn’t cut chlorination and dechlorination process out totally, but my process could help reduce costs,” she said.
Public works director Scott Kleppe gave Cole permission to perform the experiment and said he is also excited to see the data.
“I thought it would be a good project and it seemed like she had a lot of help, but just needed a place to do it,” he said.
With tightening limits on phosphates released into Iowa’s streams, both Kleppe and Cole are concerned about how waste treatment plants will further filter out these harmful elements.
“McKenna is filtering three gallons of water per tree per day,” said Kleppe. “She is removing fecal matter, which is usually treated through chlorine and then must be dechlorinated before entering the stream.”
The cost of chlorine on a chemical level is $1.15 per pound and Solon is currently using six to10 pounds per day to remove phosphates. Additionally, the Solon plant spends $1.62 per pound to dechlorinate that water. This process also uses about 1,000 gallons of potable water, a revenue stream that Kleppe says they are loosing out on.
According to Kleppe, the Department of Natural Resources is in the process of lessening the amount of phosphates allowed in treated wastewater. In order to reduce the amount of phosphates leaving the plant and maintain the new levels the plant would need to add further processes Kleppe said.
“One of the ways to do it is how McKenna is doing it or through chemicals,” he said. “I’m really interested to see what the lab data is and look at future treatment options. We would need to investigate how much land would be needed to replicate her project on a larger scale.”