Tech tested on Cape Cod could track backyard septic-system pollution
Nitrogen from septic systems has been disrupting local waterways for years, causing fish kills and blooms of toxic algae. Now, field testing on Cape Cod is playing a national role in the development of technology to monitor nitrogen — even in individual backyards — as a step toward keeping the excess out of our waters.
“There must be at least 30 septic tanks in the ground here — dozens of leachfields,” says Brian Baumgaertel, showing a visitor around the Massachusetts Alternative Septic System Test Center, where he is the director.
When an innovation in septic systems comes along, chances are, the technology has to prove itself at this facility, run by Barnstable County at the southern end of Joint Base Cape Cod.
The unassuming property has a few office trailers alongside a field dotted with septic covers and sheds. Percolating around every corner here is another science experiment.
“We use, like, anything we can here, in terms of where we put stuff,” Baumgaertel says as he steps into a small trailer to show off one of his latest projects: testing nitrogen sensors for a product-development contest sponsored by the U.S. Environmental Protection Agency.
A few years ago, the EPA launched a contest for the best low-cost sensor to monitor nitrogen from septic systems and automatically transmit the data.
Baumgartel’s team tested the prototypes.
“Nitrogen sensors aren't a new thing,” he says. “They've existed for a long time. They're used at treatment plants, but the cost is totally prohibitive for use in smaller, individual systems.”
Those sensors typically run $15,000 to $30,000. The EPA contest was looking for one priced at $1,500 or less, so it would be usable in backyard septics.
Universities and companies from as far away as Ireland brought their sensors to this trailer for an initial one-week test, he says.
On the counter in front of him is the testing setup: a barrel of wastewater the size of a large plant pot, and next to it, a metal box that contains a sensor.
“Here you can see two pipes running in. One is to draw the sample; one is to dispel some of the waste material,” he says.
“So they went through the one-week test. Then they did a one-month test, and then the final test was a six-month test, to see how well the sensor would run over a long period of time.”
Only one sensor passed the one-month test. Then, it passed the six-month test.
It was declared the EPA winner and recently finished field testing here, bringing it one step closer to commercial development.
The product has yet to come to market, sensors like this will soon be put to good use, according to Korrin Petersen, vice president for clean water advocacy at the Buzzards Bay Coalition.
“In our coastal areas around Buzzards Bay and on Cape Cod, we have sort of over-loved our estuaries,” she says — by moving to this area, “to a place that is beautiful, and putting a lot of the nitrogen into the ground.”
The Buzzards Bay Coalition plans to install nitrogen sensors as part of a model septic-system project around West Falmouth Harbor, and the Barnstable Clean Water Coalition is doing a similar project near Shubael Pond.
Petersen says sensors that send data to the cloud will be far more efficient than how conservationists monitor nitrogen now, which is to visit the sites each month, collect samples, and take them to a lab.
The winning sensor was developed at Stony Brook University on Long Island. Associate Professor Qingzhi Zhu, who designed it, says the idea was to make a device that would provide data for a long enough period without maintenance.
“This is a big challenge, because once we install the sensor in the septic system ... we want [to] let it run long-term,” he says. “This is our purpose.”
It turns out his sensor won’t meet the EPA price goal of $1,500; it will actually cost about $5,000. But individual homeowners may not be buying the nitrogen sensor — at least for now.
Instead, makers of new septic-treatment technology could use the sensor to speed up the process of proving their systems work, which right now costs about $200,000 per jurisdiction, says Bud Dunbar, president of Verified Water, the company working to commercialize the sensor that won the EPA challenge.
“The dirty little secret here is that septic systems don't work,” he says. “They separate the solids, but they don’t separate the dissolved pollutants, like nitrogen. That nitrogen is getting into our drinking water and into the surface water at an alarming rate, and it's accelerating.”
The hope here — for both business and conservation — is that more backyard septic systems will become little treatment plants of their own, in places where tying to a sewer has not been possible.