Scientists Added Bacteria To A Reactor And Achieved Something That Seemed Impossible

By Jannat Un Nisa

Scientists Added Bacteria To A Reactor And Achieved Something That Seemed Impossible

Transforming carbon dioxide, a major greenhouse gas into usable fuel sounds like something out of science fiction. Yet, Norwegian researchers have made it a lab reality. Led by Dr. Lu Feng of the Norwegian Institute of Bioeconomy Research (NIBIO), the team has successfully demonstrated that thin layers of microbes can convert carbon dioxide (CO?) and hydrogen (H?) into pipeline-grade methane with a stunning 96% purity.

This breakthrough not only offers a sustainable way to recycle waste gases but also provides a method for storing excess renewable energy and reducing reliance on fossil fuels showing how biology can replace brute-force chemistry with elegant natural processes.

At the heart of this innovation is biomethanation, a process where specialized microorganisms hydrogenotrophic methanogens transform CO? and H? into methane (CH?) and water. These archaea, though microscopic, perform an essential task: using hydrogen to strip oxygen from carbon dioxide, leaving behind pure methane.

Dr. Feng and his team adapted knowledge from anaerobic digestion traditionally used to decompose organic waste and redirected it to convert gaseous streams. Their custom-built trickle bed reactor provides a home for the microbes on plastic carriers, forming a biofilm that allows the microbial community to work continuously and efficiently.

One of the key engineering challenges was hydrogen's poor solubility in water. Since microbes can only use dissolved hydrogen, this bottleneck could limit methane production. The team overcame it by using packed columns to increase the contact area between gas and liquid. Continuous recirculation ensures a steady supply of hydrogen to the microbes, maintaining productivity.

As Dr. Feng noted, "By introducing specific methane-producing microbes into the reactors, we were able to steer the process towards more efficient CO? conversion." He emphasized that biofilm reactors have enormous potential but require precise control to perform reliably at industrial scale.

Biofilms are not random microbial sludge, they are organized, resilient communities embedded in a self-produced matrix. In anaerobic systems, they retain slow-growing species, stabilize the environment, and protect against process shocks. This makes them ideal for continuous operation and system recovery after interruptions.

Moreover, biofilm structures reduce the energy cells spend searching for nutrients and protect them from inhibitors that could slow down metabolism. This internal efficiency translates to stable methane yields and higher conversion rates.

Even advanced reactors can falter if the gas composition is off. Too much hydrogen can lead to the buildup of unwanted volatile fatty acids, harming performance. The Norwegian team found success by maintaining a balanced hydrogen-to-CO? ratio, controlling temperature, recirculation rates, and gas integrity.

Their optimized reactor achieved over 96% methane concentration without any additional purification steps. This level of quality is crucial for compatibility with gas grids, engines, and industrial burners.

The trickle bed biomethanation system is particularly well-suited for concentrated waste gases from industries like cement production, wastewater treatment, and anaerobic digestion plants. These reactors operate at moderate temperatures and near ambient pressure, minimizing energy costs compared to chemical alternatives.

Methane produced this way can be stored for months and transported through existing natural gas infrastructure. More importantly, the approach integrates with renewable electricity systems using surplus wind or solar energy to make hydrogen, which, when combined with captured CO?, becomes storable methane.

While the results are promising, mass transfer, the movement of gases through liquid and biofilm remains the key performance lever. Future designs aim to optimize contact area, film thickness, and turbulence without excessive energy input. Nutrient management is another balancing act; trace metals like nickel and cobalt are vital for microbial enzymes but must be precisely dosed.

According to the team, the focus now shifts toward scaling up and ensuring long-term reactor reliability. The biofilm approach could pave the way for durable, self-sustaining systems adaptable to various industrial gas streams.

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