LLNL researchers convert methane with 3D printed solid-state bioreactor
The lattice scaffold system was reported to outperform conventional liquid-state reactors by more than 10 times
Researchers at Lawrence Livermore National Laboratory (LLNL) have developed a 3D printed solid-state bioreactor that converts waste methane into succinate, a chemical used to make polymers, stabilize drugs and add flavor to food.
According to the team, the system performed more than 10 times better than conventional liquid-state systems while consuming less power.
Methane produced at landfills and wastewater treatment plants is often burned, and its energy value is lost. The researchers built the reactor to recover that gas as a fuel, chemical feedstock or bioproduct.
“Bioproduction using poorly soluble gases has long been limited by slow mass transfer and low efficiency because conventional liquid-phase bioreactors are not well suited for gas fermentation,” said Fang Qian, a Scientist at LLNL and corresponding author of the study.
The team printed thin lattice scaffolds and filled their walls with a hydrogel containing methanotrophs, bacteria that naturally consume methane.
“Rather than have this big tank of a ‘broth’ that you’re putting gas into, we produced these thin structures that we call scaffolds. They’re 3D printed. They have a lattice structure, and we put the microorganisms into a hydrogel that fills these really thin walls,” said Nathan Ellebracht, a Scientist at LLNL.
Hawi Gemeda, an Engineer at LLNL, said the laboratory’s additive manufacturing capabilities let the team combine material selection, printing method, geometric design and performance modeling in one workflow, and that printing allowed fast prototyping at different sizes. The team started with a 2-milliliter reactor and increased it to 1 liter.
Samantha Ruelas, a Scientist at LLNL, said the microbes perform the conversion without added heat or pressure, which can lower costs compared with chemical processes.
“Economically, chemical plants only work at large scales. At smaller landfill or wastewater treatment facilities, there aren’t really good, existing solutions that scale down. Our approach could be applied at a small plant and allow them to get value out,” Ellebracht said.
Qian added the team was extending the solid-state concept to other bioprocesses, including aerobic sugar fermentation, where oxygen mass transfer remains a bottleneck.
