Where it all goes after we flush
It takes a strong stomach to turn Oldsmar's wastewater into fertilizer. Face masks don't block the odor.
By TAMARA EL-KHOURY
Published April 24, 2007
OLDSMAR - Their jobs, like those of their counterparts across Pinellas County, are not glamorous.
Seven days a week, the 13 men who work at the Oldsmar wastewater treatment plant deal with the waste Oldsmar residents flush down their toilets, push down their garbage disposals and rinse down their drains.
The stench has knocked the uninitiated on their rears. The chemicals needed to process the sludge can burn and scar.
But Joshua Wolfe, 37, just 15 months on the job, is already immune to the unpleasantries. On a recent Tuesday, he packed 10 grams of sludge into a foil dish with his bare hands to prepare it for testing.
"This is definitely not for the squeamish of heart as far as working goes," Wolfe said.
Waste management remains one of the core - if forgotten - functions of local government for sanitation. But the vital occupation could soon change significantly under a grand plan this small Pinellas County city has for changing how it and a host of regional neighbors deal with human waste.
Oldsmar wants Pinellas County, Dunedin, Tarpon Springs and Clearwater to join it in building a multimillion-dollar biosolids drying facility to produce a safe, organic pellet-shaped product that can be sold as fertilizer.
Economics, along with environmental issues, are forcing the newfangled proposal. The sod farms in Manatee, Citrus and Hardee counties that Oldsmar and other local cities have shipped their processed sludge to for decades are being snapped up for real estate development; those that remain demand higher environmental standards.
The new technology has other benefits as well, as it uses heat rather than a caustic chemical to neutralize the biohazards in sludge.
But until the new facility and its heat-drying technology is deployed, the messy and dangerous step that gets repeated every Tuesday night at the Oldsmar plant - lime stabilization - will continue.
On a recent rainy Tuesday, Wolfe, who hopes to get his operator's license, worked alongside Jim Hudgins, 56, an 18-year veteran of the industry.
"Just so you know, this is third-degree chemical burn," Wolfe said, lifting his calf and pointing to a scar caused when lime splashed into his boot and rubbed against his skin.
By the time Wolfe and Hudgins started work, the wastewater had already gone through multiple filtering and neutralizing processes, separating most of the water from solids and foreign objects such as adhesive bandages, shoes, sand and other things.
The resulting solid moved onto the gravity belt Tuesday, looking like muddy water, and was still just 1.2 percent solid.
Then the sludge is mixed with a polymer, causing the sludge and water to repeal from each other, creating a 7.9 percent solid.
The result is thick enough to make a mud ball. What started out as 35,000 gallons of wastewater is reduced to 7,000 gallons of sludge by the time it leaves the gravity belt and is fed into one of four pits, each holding up to 12,000 gallons of sludge.
Next, Hudgins and Wolfe don face masks to protect their skin as caustic granule lime is pulled down from a silo on the roof to mix with water. The liquid lime is then pumped into the four tanks holding the sludge.
The masks do nothing to block the stench as the sludge is blended with the lime. Hudgins and Wolfe don't flinch. A novice could faint.
For three hours, the mixture is churned until the sludge's biohazards are neutralized. Then it's held for an additional 22 hours before it's hauled once a week to sod farms.
On Thursday, a tanker hauls off only 35,000 gallons of sludge from the Oldsmar plant - the eventual byproduct of nearly 12-million gallons of wastewater that flows in weekly.
"When people go to the bathroom, they don't know where it goes," Hudgins said. "They just don't want it to come back at them."