New 'wastewater' jet fuel could cut airplane emissions by 70%

Scientists have discovered how to convert wastewater into biofuel to cut plane emissions by 70% — creating a new sustainable version of aviation fuel using biomass and agricultural waste.

A new technology can convert wastewater into biofuel to cut plane emissions by 70% versus conventional jet fuel, scientists say.

Sustainable aviation fuel (SAF) currently makes up less than 1% of the fuel used in the aviation industry, but there is a pressing need to find greener fuel solutions as 2.5% of global carbon dioxide emissions come from aviation.

Mainstream aviation fuel options use oil, while alternative options have relied on fat or grease. In a study published April 25 in the journal ACS Sustainable Chemistry and Engineering, scientists outlined a technology that converts wastewater from breweries and dairy farms into the ingredients needed for SAF — namely volatile fatty acids.

The scientists deployed methane-arrested anaerobic digestion (MAAD) — a process pioneered by Meltem Urgun Demirtas, Argonne National Lab's department manager for Sustainable Materials and Processes. In this process, bacteria, rather than traditional wastewater treatments, break down the organic matter in wastewater via anaerobic digestion, converting the wastewater into butyric acid and lactic acid. These acids could then subsequently be converted into SAF, the scientists said.

However, the process also produces lactic acids, which limit the production of SAF and even lower its carbon efficiency when being converted from volatile fatty acids into SAF. To get around this, the scientists also created an electrochemical separation method, which extracts organic compounds from wastewater.

The final result was the development of an in-situ product recovery process that removes desired waste in complex mixtures through membrane separation. Coupled with anaerobic digestion, these methods enabled the team to create durable microbial communities that produced a large amount of butyric acid.