Fried turkey is often a staple of Thanksgiving meals, but making one produces a pesky byproduct: used oil.
Dumping it down the drain can cause all kinds of problems for residents and for the city – it’s hard on garbage disposals and residential pipes, and it clogs city pipes.
And often, when frying a turkey, there’s too much grease to throw in the garbage. That’s why the city of Durango, around the holidays, offers a way to get rid of that used oil.
The Durango Santa Rita Water Reclamation Facility accepted used cooking oil from dozens of residents over the holiday weekend, at no cost.
The oil, which once produced energy in the form of food for humans, will be used to generate electricity for the water reclamation facility, said Assistant Utilities Director Jarrod Biggs.
The process works something like this: Used cooking oil collected by residents is dropped off at the wastewater plant. Once all the oil is collected for the day, city employees use a forklift to move the vat to a digester with enzymes that break down waste. That digester uses microbes to consume sludge from the city, including the used oil, and turns it into methane. That methane is then pumped into a turbine that produces energy for the plant.
“We can use that (grease) in our digester to make electricity and buy down the cost of our plant,” Biggs said.
Collecting used oil and turning it into energy is nothing new for the Santa Rita Water Reclamation Facility.
It’s been doing it during the holidays for years, Biggs said. But it wouldn’t be worth it to offer the service year-round, he said.
“It’s a game of quantities. That’s what makes Thanksgiving and Christmas so good; we collect a lot more (grease),” Biggs said. “If we were collecting a couple gallons every couple days, it’s not well worth the effort to have staff on site to manage that.”
But even with the excessive amount of grease produced during the holidays, the gas produced by the grease dumped in the digester is “just a burp” compared to what the plant produces each day, said Brian Scholz, operator with the reclamation facility. The digester processes up to 7,000 gallons of sludge each day. By comparison, the city collected about 50 gallons of used oil Friday, the day after Thanksgiving, Scholz said.
The Santa Rita Water Reclamation Facility is the largest construction project the city has ever undertaken. The $54 million improvements are being made at the behest of the Colorado Department of Public Health and Environment to bring water released from that plant up to nutrient pollution standards. The improvements will also increase the plant’s capacity – six new buildings and five structures are planned as part of the facility – and rid the area of a putrid smell that often pervades areas around Santa Rita Park.
Collecting oil and using it to produce electricity is far more preferable for the city than the alternative – dumping the grease down the drain. It’s no secret that oils and fats are bad for pipes: City officials in London found a 15-ton “fatburg” made of grease and towelettes in the sewers there from people dumping grease down the drain.
Oils and fats congeal at low temperatures, causing clogs in drains that the city often has to clean, Biggs said. Grease sticks to the walls of the sewer lines, both residential and public, and can eventually clog a pipe – much like plaque can build up in someone’s arteries.
Of all the sewer overflows, causing water to leave sewer pipes where it shouldn’t in the past year, 48 percent were caused by grease and fat buildup, Biggs said.
“We are wanting to implement and get everybody in the spirit of, ‘It is not good to flush (grease),’ because it could cause you personally problems and it has a history of causing the city problems,” Biggs said.