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[GreenYes] Compost-to-Switchgrass-to-Fuel?


Re the recent post about the prospect of using compost to create biofuels,
an EPA award-winning example in Seattle was reported last April, in relevant
part (see comment that follows):

King County Executive Ron Sims announced that the county will bring about 2
million gallons of homegrown biodiesel to King County to power Metro buses.

"This is another case of the county turning waste into a resource," Sims
said in a statement. "This time biosolids from our local wastewater
treatment process are being used to grow canola that will be refined into
biodiesel to power our local transit system. This ultimate act of recycling
shows how far we've come in developing new approaches to creating energy
independence while reducing our carbon footprint."

The biosolids are retrieved from two King County wastewater treatment plants
and transported to Sunnyside to fertilize canola.

"Biosolids (are) very high in nutrients. I know that in Eastern Washington
the biosolids are used to improve soils and fertilize a lot of different
crops," said Annie Kolb-Nelson, the Media Relations Planner for King County
Wastewater Treatment Division. It's "fecal matter, basically."

The canola crop is a test of a hypothesis by University of Washington
scientists in 2003. King County teamed up with Natural Selection Farms of
Sunnyside. Soon some of the annual 115,000 tons of biosolids were put to use
by other area farmers as well.

Canola is crushed into oil by a seed-crushing facility in Sunnyside, then
shipped to Seattle's Imperium Renewables for processing into biodiesel. The
biofuel will be enough to run all Metro diesel-powered buses on a 20 percent
mix of biodiesel and ultra-low sulfur diesel for nearly a year.

The "fecal matter" comment is not exactly accurate: in fact, biosolids
across the U.S. contains a significant portion of food waste that begins its
route via a food waste disposer (aka garbage disposal; common in most U.S.
homes), traveling through underground sewers (no trucks) to wastewater
treatment plants for processing into compost-quality biosolids, often via AD
and with energy capture. After all, food waste is similar to human waste:
@ 70% water, with a slightly higher ratio of C:N than human waste, which is
helpful in most wastewater treatment processes, and enriches the quality of
biosolids. All in all, an important aspect of recycling that shouldn't be
overlooked by those focused on managing solid waste.

For an interesting essay on the historical and contemporary recycling of
human waste, read "Wasteland" in the current issue of Harper's.

Kendall Christiansen







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