Rome zeroing in on water filter
The city is running a pilot study on three carbon systems that remove more chemicals during treatment.
The city of Rome is about halfway through a test of three types of filtration systems that can absorb tiny perfluorinated chemicals used in carpets and other materials that repel oil and water.
Two would cost about $300,000 a year once they’re installed; the third would be about half that price.
“It’s a real-world pilot study,” Water and Sewer Director Mike Hackett said about the test that started in February and is expected to run into the summer.
Calgon and Jacobi are both offering coal-based GAC — granulated activated carbon — systems to replace the sand in the city’s eight water filtration beds. Hackett said they’re also testing a cheaper coconut-based carbon and they’re all working well.
Samplings of filtered water from the Etowah River show a decline in PFOA and PFOS. Extended exposure to the chemicals could cause developmental problems in fetuses and breast-fed babies, certain cancers and liver damage.
The U.S. Environmental Protection Agency lowered its advisory limits last May to a combined 70 parts per trillion, from 600 ppt. Hackett’s reports show a top level of 37 ppt, and in some samplings none of the chemicals were detected.
The next step is to extend the testing.
“We need to know how long the filters last,” Hackett said. “The coconut is almost half the price, but if we’re replacing it more often that could make it more expensive over time.”
For this round they’ll use water withdrawn from the Oostanaula River. It’s the city’s main source but it’s fed by the Conasauga River, which flows through Dalton and has higher levels of perfluorinated chemicals. Water from the Etowah and Oostanaula can be mixed if necessary to lower the levels.
John Boyd, the assistant water and sewer director, said the department just spent nearly $130,000 on two raw water pumps for the Etowah intake. The department is funded through customer fees, not property taxes.
“This will give us some redundancy as we’re dealing with PFOA and PFOS and the possibility of a low river flow,” he said.
Hackett said the Etowah is a good backup source but the Oostanaula has a greater capacity.
“That’s what we really want to run off, and I think we’re about to get there,” he said.
A GAC filtration system also can remove disinfection byproducts that form during the water treatment process. And Hackett said it’s also effective on what is expected to be the EPA’s next target: cyanotoxins, which come from algae blooms.