Aerobic bioreactor technology to power Georgia poultry farms
ATI, which expanded from Vietnam to locations in Tennessee, Nevada and California, conducted trials at five locations-one in Bakersfield, Ga., and four in Vietnam-and discovered all five pilot plants were capable of generating clean energy and reducing greenhouse gases and leakage from landfills to nearly zero, the company said.
The aerobic bioreactor technology uses less odorous components than anaerobic digestion and decreases sludge, according to Alicia McDonald, director of research for ATI's Clean Energy Division. Microbes, such as bacteria, degrade the waste mass, which could include animal manure, agricultural and forestry waste, food waste, paper and other organic biodegradable products. The feedstock is broken down into a safe, easy-to-handle, odor-free and nutrient-rich organic fertilizer, McDonald said. She added that promoting optimal conditions necessary for bacteria to thrive increases the extent of organic waste decomposition and increases conversion rates and the effectiveness of the process.
"We are working for commercialization," she said. "We're most excited about the opportunities in biomass on poultry farms." The company is developing up to 30-year contracts with Vietnamese poultry farmers near Atlanta, Ga. The fertilizer byproduct will present a savings to the farmers as fertilizer costs rise. "Those farmers have all sorts of pains hitting their wallets," she said. Besides being environmentally friendly and producing a less putrid fertilizer than the ones on the market, the bioreactor eliminates the problems of waste storage and groundwater contamination, and saves farmers money on removal and tipping fees.
In ATI's process, it's imperative to control the addition and removal of moisture and air from and into the waste mass, collect and extract methane gas and pollutants, and monitor the internal temperature of the bioreactor, McDonald said. Monitoring of these variables should be done daily, weekly, monthly and annually. Waste temperatures are maintained
by properly balancing air and liquid addition rates.
The bioreactor can run on wood chips, manure and carcasses from the poultry farms. Running 5.5 10-week cycles per year, the bioreactor can decompose 504 tons of chicken manure, 1,500 tons of wood chips and 54 tons of defeathered chicken carcasses per cycle, McDonald said. The manure can produce about 30,240 cubic meters of methane, which converts to about 317,000 kilowatt hours of energy, and the wood chips can produce about 15,120 cubic meters of methane, converted to about 159,000 kilowatt hours of energy, she said. The poultry farmers will use that energy for cooking and heating, along with powering their homes. "Our first and foremost goal is to make sure these farmers can sustain themselves," McDonald said. Any extra energy may be sold to the grid and ATI already is in discussions with some utility companies to develop agreements.
ATI has conducted other renewable energy projects in Vietnam, many in the solar energy sector. "We have years and loads of energy projects we've done with the Department of Energy in the U.S. and many major energy corporations all around the world," McDonald said. "There's lots of new stuff on the horizon for ATI."
The company would also like to experiment with municipal solid waste as a feedstock for its aerobic bioreactor, she said. The technology would not have to be retrofitted, but would be required to operate on a grander scale.