The City of Gainesville is home to the University of Florida and the Florida Gators — and to an innovative water reclamation facility with an exemplary biosolids program.

 

The Kanapaha Water Reclamation Facility (WRF), owned by Gainesville Regional Utilities, is tucked away in the southeast corner of the city, where a landscape of student apartments merges with single-family homes. Further east, the city gives way to farmland.

 

Just 12 miles down the road from the Kanapaha facility, Class B biosolids are transported by tanker trucks for land application at the Whistling Pines Ranch where they supplement inorganic fertilizer. Biosolids from GRU’s Main Street Wastewater Treatment Plant are also land-applied there.

 

“Recycling biosolids is a sustainable, environmentally beneficial practice that improves and maintains productive soils and also reduces chemical fertilizer use,” says Paul Davis, utility engineer. Team effort is inherent throughout GRU. Biosolids from more rural neighboring towns, like Hawthorne, Waldo, and High Springs, are managed through the GRU plants.

 

“We take their waste activated sludge,” says James (Jamie) Hope, director of water reclamation facilities and lift stations. “It’s at 1 to 1.5 percent solids, and they have no way of thickening it. We charge them, but only to cover costs.”

 

Hope says the state Department of Environmental Protection (DEP), appreciates the practice because of the help GRU provides for the smaller communities who may not otherwise be able to recycle their biosolids. GRU also partners with the university and accepts thickened solids from an on-campus treatment plant.

 

Treat and Separate and Treat Again

Wastewater entering the Kanapaha WRF is treated with an activated sludge process. Secondary effluent is run through a sand filter and disinfected with chlorine. Effluent is either pumped to four 1,000-foot-deep Floridan aquifer injection wells, or to 1,000 reuse customers who use it for irrigation. The water is treated to primary and secondary drinking water standards.

 

Reuse water goes to nearby neighborhoods, commercial properties, parks, aesthetic water features, infiltrating wetlands, and a golf course. Because only 31 percent of the effluent is now reclaimed, the facility is always on the lookout for new customers. New developments are usually connected to the reuse system, but as the building market has slowed, so has the acquisition of new customers.

 

At Kanapaha, solids from the secondary clarifier that are not returned to the aeration basin are pumped to three aerobic digesters that operate in series. The first and second are sized at 0.66 and 0.64 million gallons and use coarse-bubble diffused aeration. The third digester (0.64 million gallons) uses a floating mechanical surface aeration system. The Main Street plant incorporates two 1.29-million-gallon digesters that use both coarse-bubble and surface-mechanical aeration systems.

 

Biosolids are thickened using two Ashbrook and two Andritz gravity belt thickeners, each two meters wide. Only one gravity belt thickener is used at a time, leaving the others available for maintenance and cleaning. Just before the thickeners are mixing chambers where ClariFloc polyacrylamide emulsion polymer (SNF/Polydyne) is added.

 

In-house trucking

From the thickeners, biosolids are stored in below-grade tanks until a truck pulls in for loading. Coming out of the digesters, the solids content ranges between 1.2 to 1.5 percent. After thickening, the goal is to produce a product with no more than 5 percent solids. Anything thicker would be difficult to pump into and out of the tanker trucks.

 

GRU owns the tanker trucks — two 6,000-gallon and two 4,000-gallon units. It takes about 30 minutes to load the tank at the plant, and about two hours total for trucks to travel to the application site and back. Three to four truckloads of biosolids are delivered from the Main Street plant daily, and five to six loads from the Kanapaha facility. At the farm they’re pumped into a storage tank. GRU pays for an employee at the farm to manage the application process.

 

“It’s beautiful,” says Davis. “For more than 25 years we’ve been doing it. We’re lucky in Gainesville that we can go right out of town. Since the land application program is agricultural in nature and the city is making a long-term investment at the site, GRU’s land application program preserves Alachua County rural areas, farming and crop production, and supports future agricultural uses at and near the application site.”

 

At the ranch, biosolids are spread using a GEA Houle spreader system. They are either injected 6 inches below the surface or surface-applied with adistributor. If they are surface-applied, the solids are disked into the soil. Kanapaha’s biosolids professionals believe they have a high-quality product that economically is a perfect fit. So, for the time being, there are no plans to raise the biosolids grade from Class B to Class A.

 

“We have to account for paying customers when considering costs to treat the biosolids,” says Davis. “The program is the most cost-effective and environmentally sustainable method of providing wastewater treatment services to GRU’s customers, and it saves local communities from having to finance and manage their own biosolids programs.”

 

Operator as teacher

Beyond concern for protecting the public, Hope and others at the plant believe education is a key component of their jobs. “We are very engaged in the community,” says Hope. “We do approximately 50 tours a year, from college-age students to home-schoolers.”

 

Public utility professionals from all over the world, visit the plant. Visitors tour the treatment plant and can also explore the adjacent Chapman’s Pond and nature trails. The land spans 66 acres and includes 1.8 miles of trails open for public use. Ponds, streams, waterfalls and fountains in the park are all supplied by reclaimed water and include educational signage. Chapman’s Pond has a berm and barrier-free access so that everyone can see the nests and bird boxes along the perimeter. A kiosk provides bird identification.

 

GRU also constructed a series of man-made wetlands at nearby Kanapaha Middle School. It serves as a living laboratory for students as they observe the ecosystem provided by the reclaimed water. Educating students goes beyond the mechanisms of treatment plant operation and biodiversity to potential careers. That grows more important as treatment plant operators approach retirement with no replacements in sight.

 

“In Florida, the average age of wastewater treatment plant operators is 52 years old,” says Hope. “We go to career day for recruitment.” With all the effort put into plant tours, education and community outreach, it’s no surprise that people gain a new understanding for wastewater treatment and biosolids management. Many are outright won over.

 

“I have given hundreds of tours,” says Hope. “Afterward, people have much more of an appreciation for what we do. They become our advocates and allies.” And you can never have too many of those.