Thin biofilm can transform CO₂ into renewable energy

NIBIO has contributed to growing a technique for turning greenhouse gases like CO₂ or CO into biomethane—a renewable power supply. Utilizing skinny layers of microorganisms, so-called biofilms, greenhouse gases might be remodeled into clean-burning gasoline.

Carbon-based gases reminiscent of carbon dioxide (CO₂) and carbon monoxide (CO) are sometimes related to air pollution and local weather change. However what if these gases could possibly be changed into one thing helpful as a substitute—like clean-burning gasoline?

That is what Dr. Lu Feng and different researchers have been engaged on. The objective of the collaboration has been to develop a brand new methodology for producing inexperienced biomethane, a sustainable different to pure gasoline.

By way of 5 scientific papers, the researchers have documented how biofilm-based processes can be utilized to provide biomethane with over 96% purity.

The papers seem in Biomass and Bioenergy, Journal of Environmental Chemical Engineering, Bioresource Technology Reports, Bioresource Technology and Biotechnology for Biofuels and Bioproducts.

Engineered biofilm for focused conversion

A biofilm is a layer of microorganisms that develop on surfaces. The microbes work collectively and kind a type of neighborhood that may course of gases and switch them into methane.

“As an alternative of decomposing natural waste, as is finished in conventional biogas manufacturing, the biofilm methodology captures and processes gasoline streams utilizing self-selected microorganisms harbored inside skinny biofilm beneath oxygen-free circumstances,” Dr. Feng explains.

“Biofilms are widespread in nature,” he continues. “Our intention has been to engineer the biofilm to work for us for focused conversion, both by utilizing mounted or transferring mattress reactors. This opens new alternatives to transform climate-impacting gases into useful power.”

Amongst different issues, the researchers experimented with including chosen microorganisms—a course of often called bioaugmentation—to enhance methane manufacturing.

“By introducing particular methane-producing microbes into the reactors, we have been in a position to steer the method in direction of extra environment friendly CO₂ conversion,” says Dr. Feng.

Biofilm reactors preserve excessive methane high quality and tolerance

The researcher says that the biofilms they’ve developed present a secure and environment friendly course of.

“They assist retain the microbes, enhance gasoline–liquid contact, and largely improve contact floor for the response. Additionally they tolerate dangerous substances that will in any other case disrupt gasoline manufacturing.”

Particularly, biofilms will help handle challenges reminiscent of excessive ranges of ammonia and hydrogen sulfide (H₂S). These are substances usually present in industrial gasoline streams and might be problematic in typical bioreactors.

“In one in every of our research, we examined how biofilm reactors deal with H₂S which is a poisonous gasoline that may considerably cut back methane manufacturing,” says Dr. Feng.

“The outcomes confirmed that techniques with out biofilm misplaced as much as 30% of the methane, whereas the biofilm reactors maintained excessive methane high quality even at extraordinarily excessive H₂S content material.”

The researchers additionally examined the impact of ammonia, which often inhibits methane manufacturing. On this research, they used a sort of reactor known as AnMBBR (Anaerobic Transferring Mattress Biofilm Reactor), and located that the biofilms have been in a position to produce methane even at excessive ammonia concentrations.

“Excessive ammonia might be accrued when fish sludge, animal slurry, or meals waste are used to provide biogas”, says Dr. Feng.

“Our evaluation confirmed that the biofilm contained microbes that tolerate ammonia, together with a bunch known as Methanothermobacter, which might use H₂ and CO₂ to provide methane.”

Unlocks nice potential from unconventional substrates

In one other research, the researchers examined the biofilm methodology on syngas—a mix of hydrogen and carbon monoxide.

“This might unlock the potential of utilizing waste to provide biomethane, for instance, plastic waste and woody biomass, which beneath regular circumstances doesn’t degrade in a bioprocess,” Dr. Feng says.

The researchers discovered that including additional hydrogen may improve methane manufacturing.

An excessive amount of hydrogen, nevertheless, led to imbalance within the course of.

“This exhibits that biofilm reactors have nice potential, but in addition that they require cautious management to perform optimally at an industrial scale,” says Dr. Feng.

“Biofilm-based processes provide a strong and versatile platform for future biogas manufacturing. This might change into an necessary contribution to lowering dangerous gasoline emissions whereas producing renewable power,” he provides.

Offered by
NIBIO – Norwegian Institute of Bioeconomy Analysis