http://www.pwmag.com/industry-news.asp?sectionID=760&articleID=547650

From sludge to fuel

California is the first state to power local industry with
wastewater-treatment byproducts instead of coal.

Source: PUBLIC WORKS MAGAZINE

Publication date: August 1, 2007

By Amara Rozgus

Five Los Angeles-area sanitation districts have signed on with
Atlanta-based EnerTech Environmental, a developer of renewable energy
technologies, to convert their biosolids into a renewable fuel, called
E-Fuel.

Scheduled to open in mid-2008, the nation's first commercial
“sludge-to-fuel” facility is expected to convert 675 wet tons per
day of sludge into about 145 tons per day of E-fuel, which will be sold
to a local cement kiln as a coal alternative.

Until the development of the patented “Slurry-Carb” process,
wastewater treatment plants have disposed of their primary
byproduct—biosolids—by selling it as fertilizer, shipping it to
landfills, or incinerating it onsite to power their pumps and boilers.
The latter option has become less popular in light of tougher air
restrictions and other sludge-to-fuel technologies, such as thermal
drying, that often consume more energy than the resulting product
generates.

Using heat and pressure, the SlurryCarb process chemically carbonizes
the organic matter in the biosolids and ruptures the cell walls,
releasing bound water. The resulting slurry is dewatered to 50% total
solids using centrifugation rather than evaporation; it then dries using
about two-thirds less energy than conventional drying methods. The
energy savings result in about one-third reduction in overall cost when
compared to traditional biosolids drying methods. The final product,
E-Fuel, can be sold as a renewable fuel with approximately 7000 BTU per
pound.

 

The nation's first “SlurryCarb” facility, shown here, is sited on an
old landfill next to a wastewater treatment plant that serves Rialto,
Calif. Fees from communities that bring their sludge to this facility
will go to the city's general fund. Source: MBN Group Inc. 

The SlurryCarb facility will be located next to the wastewater treatment
plant in Rialto, reducing hauling costs of the biosolids as well as
fossil-fuel emissions. None of the public works entities
involved—Rialto, San Bernardino, Riverside, Orange County Sanitation
District, and Los Angeles County Sanitation District—contributed to
funding the new facility, which is owned and operated by EnerTech. The
$78 million project is financed through private equity funds.

While the new option won't necessarily save the agencies any money—in
some cases, sending biosolids to the SlurryCarb facility will cost more
than traditional disposal alternatives—it's environmentally friendly.

“Why spend more money on biosolids removal when you can spend less?”
says Layne Baroldi, legal affairs liaison with the Orange County
Sanitation District. “Because it's the right thing to do.” The
county estimates that the SlurryCarb method will cost $72 per ton
compared to the $50 per ton it's been spending to send biosolids to a
landfill in Arizona.

But continuing to ship biosolids out of state is not environmentally
beneficial. California is very sensitive to environmental issues,
especially the reduction of fossil fuels. By allowing this
facility—and possibly more in the future—to be built, the state will
reduce fossil-fuel emissions from trucks. In addition, using a renewable
fuel keeps power plants from using precious non-renewable fuel.

Rialto may even make money in the deal. EnerTech has helped pay to close
the landfill on which the SlurryCarb facility will sit; the landfill was
due to close anyway, so Rialto got off easy by not having to pay the
whole price. Plus, Rialto will charge $0.50 per wet ton to agencies that
bring their biosolids to the facility.

Web extra: 

For a demonstration of the SlurryCarb process, visit:   HYPERLINK
"http://www.enertech.com/technology/slurrycarb.html" 
www.enertech.com/technology/slurrycarb.html  

