From trash to ash: Where your waste goes each week
After throwing out a banana peel, you probably never think about it again. When you put trash cans at the curb each week, you also likely don’t wonder what happens to the waste. Yet the moment that banana peel is tossed into a garbage truck, it kicks off a long journey before ending up in a landfill.
York County produces about 1 million pounds of garbage a day, said Jennifer Cristofoletti, the community services outreach coordinator for the York County Solid Waste Authority. “Each of us produces about two pounds of garbage a day.”
York County is home to one of just 75 waste-to-energy facilities in the United States. When the York County Resource Recovery Center, owned by the authority, incinerates waste, it produces not only ash but steam, which creates power through a turbine and generator system. That produces enough energy to power York City each day, or about 36 to 46 megawatts per minute per day, Cristofoletti said.
The energy is sold to the Pennsylvania-New Jersey-Maryland Grid, according to the York County Solid Waste Authority's website.
When garbage trucks arrive and leave, they are weighed at a scale house to keep track of how much waste comes in each day, Cristofoletti said. Next, trucks go to the tipping hall, a large garage with a pit the length of a football field alongside the back wall. The pit is narrow but 50 feet deep.
The garbage is dumped onto the tipping hall floor, where workers in Bobcat tractors pull aside noncombustible items like metals or toxic items like medical waste. Once the items that aren't appropriate to burn are removed, the Bobcat tractors push the waste into the pit.
Now the waste-to-energy process begins. Like an arcade game, a giant crane and claw mounted to the garage ceiling pick up trash from the pit. An operator sits a few stories above the pit, moving the claw to grab 8 to 12 tons of garbage at a time. From the pit, the claw takes trash and drops it into one of three chutes that lead to the three combustion barrels.
Hydraulic ram feeder arms continuously push the garbage from the chutes into a combustion barrel. They are like cement truck barrels, but they only make six rotations per hour. Natural gas starts the combustion process and is shut off when it becomes self-sustaining. The barrels can heat up to between 1,800 and 2,200 degrees Fahrenheit, Cristofoletti said.
The leftover ash is now called bottom ash. Since the combustion barrels are tilted, the bottom ash falls into cold water conveyors below. The material is taken to the ash recycling facility across the road, where sand, metal and other aggregates are taken out by machines. Next the wet ash is pressed into a “cake.” Some of the cakes are mixed with fly ash, which is produced from the air filtration process. Now the ash is finally ready to head to Modern Landfill.
During combustion, water is run through pipes that span the interior walls of the barrel. The heat produces steam in the pipes, and the steam then goes through a secondary heating system. Next the steam travels to the turbine, which powers the generator. The water is from the York Water Co. and is largely reused for the process via water collection built into the system.
The three combustion barrels and steam-powered generator make enough energy to power 20,000 homes daily, Cristofoletti said. Using a waste-powered system, the recovery center saves 375,000 barrels of fossil fuels each year, according to the waste authority's website.
Even after the ash and energy producing processes are complete, some toxins are also produced. Gasses and particulate matter from the combustion process must be filtered out before the air is released into the atmosphere.
After combustion, the air is sent to an air pollution control unit: a dry scrubber and then bag house. In the dry scrubber the air is sprayed with a lime slurry to neutralize the gasses. That creates particulate matter called "fly ash" from the dried, unreacted lime and reaction products, Cristofoletti said. Fly ash, which contains some harmful particles, must be combined with the bottom ash to balance out the toxins.
Next the air goes to the bag house, where particulate matter is removed. A series of long fabric bags are propped open with cylindrical metal cages inside of them.
As the scrubbed air passes through, the fly ash sticks to the bags. Every 15 minutes, the bags pulsate, dropping the fly ash to the ground.
Finally, the air leaves the bag house and is released through the three stacks in a 324-foot-tall cement pillar. The pillar contains all three stacks. The very small amount of particles left in the air at that point will be harmless by the time it reaches the ground, Cristofoletti said.
In the base of the stacks is a Continuous Emissions Monitoring system. That shows the amount of particulate matter in the air as it goes up into the stacks. The CEM system only allows particulate matter registering between 0 and 10 on the meter.
“A real-life example, you know, one puff of cigarette smoke would send the meters to 30,” Cristofoletti said. If the amount of particulate matter detected is at 10 for more than 15 minutes, an alarm will sound to let workers know they need to check the air-cleaning systems for an issue, she said. The Department of Environmental Protection can access data from the CEM system at any time, according to Cristofoletti.
By the time ash is sent to Modern Landfill, it is much smaller than its original form. The original waste is reduced by 90% when turned into ash, Cristofoletti said. Even though incinerating waste helps reduce the amount of waste in landfills, York County is still searching for a new place to take it.
The York County Solid Waste Authority is trying to find a new place to put its waste if Modern Landfill closes in 2025 as scheduled. While a part of the problem is how much waste is produced, the biggest challenge will be finding existing facilities to take waste as opposed to creating new landfills. The search for new waste storage facilities has begun, but no specific facilities have been decided upon.
— Reach Noel Miller at NMiller3@yorkdispatch.com or via Twitter at @TheNoelM.