Technology that prevents fouling in bioreactors for better CO2 capture

May 05, 2023 | Biotechnology

Successful reduction of carbon emissions affects global climate and it includes looking into negative emission technologies and other sources before they get released in the first place. One of the biological approaches to reducing greenhouse gasses aside from planting trees, is algae. About 50 percent of the global carbon dioxide is absorbed by marine algae alone. They grow anywhere - 10 to 50 times faster than terrestrial plants.

Algae have been grown in transparent tanks or tubes supplied with carbon dioxide for the conversion of greenhouse gasses into other compounds. This process produces 7 to 10 times higher yield than ponds for a given amount of land. However, this process can lead to the unwanted buildup of algae which leads to frequent shutdowns, reduction of efficiency, and costly operational cleanouts.

Researchers from the Massachusetts Institute of Technology (MIT) developed an economical technology that significantly limits fouling on the walls of photobioreactors, allowing more photosynthesis to happen. The solution comes with the transparent containers being coated with a material that can hold a small electrostatic charge.

Algae cells naturally have a small negative electric charge on their membrane surfaces and the team thought of using electrostatic repulsion to push excess algal growth away. A negative charge is created on the vessel walls, using high-performance dielectric material or an electrical insulator with high permittivity. With only a small voltage, this material causes a change in surface charge. This electrostatic interaction does not not shock the algal cells and the scientists are able to control cell adhesion. And since it isn’t cell specific, there is potential for using it with other cells, such as mammalian and bacterial cells.

The team used both silicon dioxide and hafnium oxide as dielectric materials and they proved to be more efficient compared to conventional plastics used in making photobioreactors. These materials can be applied in a coating that is thin (10 to 20 nanometers thick) to a photobioreactor system.

Depending on the application, the system has massive implications and can be used to either repel or attract cells by the reversal of voltage. A similar setup can be done with human cells in the production of artificial organs by introducing a charged scaffold that could attract cells into the right configuration. Seeing its effectiveness in lab-scale tests, this technique can be assimilated to commercial production with the incorporation of new developments.