Franklin's H2o czar shows off water purification pilot facility

From the outside, the pipes, meters, tanks and taps that fill most the space inside the City of Franklin's cutting-edge water purification demonstration facility could be mistaken for a high-end barn.

The new pilot facility is expected to significantly increase the availability of water in Franklin — and, by setting a precedent, likely encourage similar processes statewide.

The facility is the state's first facility to augment drinking water supplies in addition to applying this technology to treat water to purified standard, said Michelle Hatcher, the director of the city's water management.

The water reclamation could also help the city's budget.

"Two thirds of our water supply is purchased," Hatcher said. Franklin purchases the water from Harpeth Valley Utilities District, which pulls water from the Cumberland River.

In simple terms, the facility, which is located at the intersection of the Harpeth River and Interstate 65, is a small-scale test case for purifying water. It produces about 10 gallons of purified water per minute as compared to 3 million gallons a day at larger facilities. Think of the process like a much higher-level home water filtration system.

If it works, Franklin — and maybe other municipalities and utilities — will build a similar, full-scale water reuse facility.

The water will reach potable levels, but won't be used for drinking. Instead, it could be used to wate fields or in other ways tap water might be used.

"This facility is specifically only geared around advanced technologies," said Hatcher, who recently led a group around the facility. "So it's important to note, (we are) looking at how we can reuse water and the advanced kind of treatment techniques that we can do with water to take it to that next level."

Step 1: Membrane Filtration

High pressure pumps pull water through the hollow fiber membranes, leaving contaminants behind. Contaminants such as particles, bacteria, and protozoa are collected and filtered out.

Step 2: Ozonation

Oxygen molecules from the air are subjected to high electrical voltage to produce ozone gas, which is infused into the water to destroy microorganisms. The ozone is consumed and converted to dissolved oxygen.

Step 3: Biofiltration

Water flows through a filter with millions of biologically active carbon granules. Living bacteria breaks down organic compounds and contaminants.

Step 4: Granular activated carbon

Water flows through a canister of carbon granules. The granules are activated, which create small pores and lots of surface area to adsorb chemicals in the water.

Step 5: Ultraviolet disinfection with advanced oxidation

The vessels are fitted with ultraviolet lamps, which produce rays similar to extremely concentrated sunlight. A powerful disinfectant is injected to form powerfully reactive molecules that destroy microconstituents in the water including pharmaceuticals and personal care products.

A decade ago, the city developed its Integrated Water Resources Plan, a roadmap for using water resources in Franklin and stewardship of the Harpeth River. The plan projected growth in the city's southeast along the Interstate 65 corridor — where growth continues — and the city secured land for a new clean water facility.

In recent years, the city opened a $132 million wastewater collection and treatment facility, which broke ground in 2018. That facility, located on Claude Yates Drive on land behind Franklin High School, currently provides the water for the pilot facility.

"This is innovative for Franklin, but these processes are being utilized across the nation and around the world. They are proven to be safe, sustainable, and forward-thinking, and they position our community well for the future on so many levels," said city administrator Eric Stuckey.

Once the research is completed at the pilot facility this summer, the city and state Department of Environment and Conservation will evaluate the data and determine the best course of action.

Franklin's Board of Mayor and Aldermen will then make a determination on next steps in terms of design and construction of a new clean water facility in southeast Franklin.