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Advocate Lake Highlands (October 2009) : Page 40

trashto treasure How it works: bioreactor technology • The yucky mix flows from the storage tower into horizontal perforated pipes that line the landfill. • On the east end of the dump stands a tower that stores sludgy recycled trash water con- taining bacteria, fungi, and other microorgan- isms or microbes. • 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 pro- cessing 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 Number of homes that can be heated daily by the landfill’s methane emission 30 Percentage of time by which the land- fill’s life expectancy should increase because of bioreactor technology 20 Number of landfills in the nation using bioreactor technology (Dallas was the first landfill in texas to try it) 308 Number of methane wells reaching down into the Dallas landfill 120 Feet each well extends into the land- fill waste (the waste is at least 130 feet deep any place a well exists) $100,000 Average net amount the city makes each month from the sale of methane 250,000 Gallons of liquid that can be pumped into a cell each day to jump-start the microbes in bioreactor technology 40 This system helps Dallas turn trash to money by speeding up the decomposition process that would naturally occur. On the east end of the dump stands a tower that stores sludgy recycled trash water containing bac- teria, fungi, and other microorgan- isms or microbes. the yucky mix flows from the stor- age 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. 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. the economy of space Garbage service is built-in for the city’s single-family homes (it accounts for the biggest chunk of OctOber 2009 advocatemag.com/lake-highlands the $20.98 charge on our monthly sewer bill), but multi-family com- plexes 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 mil- lion in 2009, but a good portion of its customer base is the construction industry, and because the economy has weakened, Nix says, construc- tion 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. because the technology breaks down garbage more quickly, it means the amount of garbage in each cell will decrease more quickly, trans-

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