trash to treasure

How it works: bioreactor technology

• On the east end of the dump stands a tower that stores sludgy recycled trash water containing bacteria, fungi, and other microorganisms or microbes.

• The yucky mix flows from the storage tower into horizontal perforated pipes that line the landfill.

• The liquid is then injected into the trash, where it acts as food for hungry microbes, causing the trash to decompose much faster than it normally would.

• Accelerated decomposition means faster generation of valuable gaseous byproducts — methane and carbon dioxide.

• Another set of vertical pipes act like wells, sucking up the gas and transferring it to a processing facility on the west end of the land.

• Machinery at the processing site sterilizes and separates the gases, preparing them for sale to Atmos Energy and other customers.

25,000

Percentage the yucky mix flows from the storage tower into horizontal perforated pipes that line the landfill. the liquid is then injected into the trash, where it acts as food for hungry microbes, causing the trash to decompose much faster than it would normally.

On the east end of the dump stands a tower that stores sludgy recycled trash water containing bacteria, fungi, and other microorganisms or microbes.

Accelerated decomposition means faster generation of valuable gaseous byproducts — methane and carbon dioxide.

Another set of vertical pipes acts like wells, sucking up the gas and transferring it to a processing facility on the west end of the land.

Machinery at the processing site sterilizes and separates the gases, preparing them for sale to Atmos energy and other customers.

T He Economy Of Space

Garbage service is built-in for the city’s single-family homes (it accounts for the biggest chunk of the $20.98 charge on our monthly sewer bill), but multi-family complexes or businesses have to pay by the ton to dump trash at the landfill. because Mccommas bluff is so large, Dallas accepts trash from other counties, commercial outfits and anyone else willing to pay its $21-per-ton fee. that’s the most substantial way the city generates revenue on Mccommas bluff, a total of $25 million in 2008. the city expected to net $28 million in 2009, but a good portion of its customer base is the construction industry, and because the economy has weakened, Nix says, construction tapered off so the city expects to net $23 million. the landfill opened in 1981 and is projected to be used until 2031, when it originally was estimated to fill up. but bioreactor technology could mean it will last much longer than that — another 22 years, Smith says. lating into more space in the landfill — and Smith says, space equals money.

The cost to run the landfill was $18.5 million in 2008, so with dumping fees plus residential garbage fees (roughly $4 million annually) the city expects to earn roughly $9 million in 2009.

And if, as Smith predicts, new technology evolves that changes landfills from finite to infinite space, McCommasBluff could continue operating as a city cash cow for decades and even centuries to come.

REDUCE, REUSE... YOU KNOW THE REST

Recycling has come a long way in Dallas, Nix says. “We were pretty behind for a long time. We did not follow the green track in late ’80s and early ’90s,” she says.

In 2005, only about one in four Dallas households recycled. Today, Nix says almost half of Dallas homeowners recycle: “Our count of recyclers, as provided by route drivers and further estimated based on big blue cart deliveries, is 46 percent.”

The city’s goal for the “Too Good To Throw Away” program, which educates homeowners on recycling and provides the blue bins for singlefamily residences, was 50 percent of eligible households by 2011.

“We ought to get there a bit earlier than estimated,” Nix says. “We’re certainly seeing big strides in the amount of recycling materials we’re collecting.”

Effective recycling programs mean more landfill space; our current recycling rate means we save more than a month of landfill space every year.

“When we bury something, we hope it will degrade,” Smith says. “Everything we want to go into the landfill is not this type of stuff [gesturing toward a plastic water bottle from which he’s drinking]. We want it to decompose.”

The city doesn’t sift through garbage to mine recyclables, so any non-biodegradable items tossed in the trash remain in the landfill taking up space.

“We would love for it to be out,” Smith says. “It’s not a perfect world but it is getting better.”