St. Petersburg to build waste-to-energy plant
ST. PETERSBURG -
Every year, the city transports roughly 36,000 tons of treated sewage to Polk County to be used as fertilizer.
That simple form of recycling reduces the burden on city landfills, but trucking the waste as much as 80 miles away still costs the city about $2.6 million per year.
Now, city officials are planning to save money by turning the sewage into renewable energy that could be used to power its water treatment plant or be converted into natural gas to fuel service vehicles.
Last week, the City Council approved a $2.9-million contract with a consulting firm to design a system to convert methane gas from sewage into energy at its wastewater treatment plant on 54th Avenue South.
The plant would then be used to process all of the city’s wastewater solids, known as sludge. That would lower maintenance and equipment costs at other plants and reduce the city’s diesel usage by 1,600 gallons a day, said Mike Connors, St. Petersburg’s public works administrator.
Over a 20-year period, the project is estimated to save the city roughly $30 million, Connors said.
“We reduce our greenhouse gas emission, lessen our reliability on foreign oil. We reduce odors that are emitted at our three remaining plants,” Connors said. “It’s very favorable.”
Under the proposal, sludge from the city’s two other wastewater treatment plants would be piped to the plant on 54th Avenue. There, it would be processed in new tanks known as anaerobic digesters that are capable of storing the methane byproduct that can be converted to energy.
“We’re then going to cleanse that gas and use it to run a generator to power the plant or compress it into a tanker truck to fill tanks,” said Connors.
The program could also help boost the St. Petersburg’s “green” image, which recently took a hit after a report commissioned by the League of Women Voters and the St. Petersburg Area Chamber of Commerce criticized the city for not having universal curbside recycling.
The city has focused its efforts on recycling construction debris and yard waste, which costs the city $1.1 million to collect, grind and transport to farms in Manatee County to be used as mulch.
One possible future recycling project would be to convert the yard-waste to energy using thermal processing. City officials plan to evaluate that process in the next five years.
Design of the energy system at the 54th Avenue plant is expected to take as much as 15 months. Construction would take another two years.
The conversion of sewage from a waste product that is expensive to dispose of into usable energy would be a huge benefit for the city and taxpayers, said Mayor Bill Foster.
“There’s nothing sexy about waste; this is a process that we as the government have to provide and it comes at a cost,” Foster said. “Converting that into a sellable or usable product is incredible.”