Researchers develop method to make renewable natural gas directly from waste
In Washington, Washington State University said that a pilot study of a new method for treating sewage sludge from a wastewater treatment plant efficiently created renewable natural gas while reducing the cost of the treatment.
When the researchers pretreated sludge collected from a nearby wastewater facility, they produced 200% more renewable natural gas compared to current practices and reduced the final disposal cost by nearly 50%. Renewable natural gas could be used in the same way as fossil-fuel based natural gas for a wide variety of uses, including for electricity generation, home heating, or for transportation without the same climate effect as fossil fuels, the university said.
“This technology basically converts up to 80% of the sewage sludge into something valuable,” said Birgitte Ahring, corresponding author on the paper and a professor in WSU’s Bioproducts, Sciences, and Engineering Laboratory and the Gene and Linda Voiland School of Chemical Engineering and Bioengineering. “If we can replicate this work on other organic materials, we’ll have a waste treatment technology that is world-class when it comes to efficiency.”
For their study, the WSU research team added a pretreatment step, treating the sludge at high temperature and pressure with oxygen added before the anaerobic digestion process. The small amount of oxygen under high-pressure conditions acts as a catalyst to break down the long polymer chains in the material. The researchers showed that their pretreatment resulted in reduced cost to treat the sewage from $494 to $253 per ton of dry solids.
The team then used a novel bacterial strain that they discovered and isolated to upgrade the biogas, converting carbon dioxide with hydrogen into methane or renewable natural gas. The researchers analyzed and verified the renewable gas, showing that it was 99% pure methane.
The researchers are working with WSU’s Office of Innovation and Entrepreneurship and have patented the bacterial strain. They are now working with an industrial partner to develop a larger scale project.
Category: Research
