Pilot technology for direct capture of CO₂ from air by a cascade of biological and non-biological membranes (m-DAC4)

The "m-DAC4" project is aimed at the development of an innovative hybrid technology for capturing carbon dioxide (CO₂) from the atmosphere. The main issue that the project concerns is the growing need for efficient and sustainable methods of capturing CO₂ in the context of global climate change and the increase of anthropogenic carbon emissions. Specifically, the focus is on developing technologies that can regulate atmospheric CO₂ levels regardless of its origin. The project's scientific hypotheses focus on the potential of combining two CO2 capture technologies: (1) specialized membranes (both biological and synthetic) and (2) direct capture from air (DAC) - to create a more efficient system. The scientific novelty and innovation of the project consists in the creation of an entirely new 4-step hybrid of a direct-capture system with membrane-separated chambers to precisely capture and regulate CO₂ levels. This system will be monitored by precise laser-based methods. 

Project Implementation Summary

The project developed and validated the concept of a modular cascade system for the direct capture and biological reduction of CO₂ in an airflow. The research activities covered the structural design of the system, the development and testing of different membrane materials, CO₂ monitoring, and the application of laser technologies to stimulate biological activity.

Main Activities

• Structural models and a prototype architecture of the modular gas-contact system were developed.
• Synthetic and biological membranes were selected and experimentally tested, including cellular membranes containing microalgae and enzymatic membranes incorporating carbonic anhydrase.
• The compatibility, stability, and applicability of the different membrane materials were evaluated under conditions relevant to their intended operating environment.
• Different approaches to monitoring CO₂, temperature, and relative humidity (CO₂/T/RH) were investigated, including an experimental laser-based CO₂ measurement system.
• Femtosecond laser experiments were conducted on cellular biological membranes. Under specific irradiation regimes, a positive effect on their CO₂-capturing activity was observed.

Key Technological Decisions

The results led to the optimization of the initial concept and to several key technological decisions:

• simplification of the original four-chamber architecture into a two-chamber validation sub-model;
• use of commercially available CO₂/T/RH sensors for reliable inlet and outlet monitoring;
• prioritization of biological membranes due to their closer alignment with the objectives of the developed technology;
• cascade arrangement of the membrane modules, with the cellular module serving as the primary CO₂-capture stage and the enzymatic module capturing the residual CO₂;
• use of replaceable membrane cassettes to facilitate maintenance, testing of different materials, and future system upgrades.

Main Outcome

The structural design of a modular cascade gas-contact system with replaceable biologically active membrane cassettes was finalized. The developed technology reached Technology Readiness Level 5 (TRL 5) — technology validated in a relevant environment.

Dissemination and Technology Transfer

The project results were presented and disseminated through:

• participation in three international scientific conferences;
• participation in one international exhibition forum;
• two scientific publications;

(https://doi.org/10.3390/ma19132869   

https://doi.org/10.7546/CRABS.2026.07.06)

• the utility model “Modular Cascade Gas-Contact System for the Biological Reduction of Carbon Dioxide in an Airflow.” (https://portal.bpo.bg/bpo-registers/utility-models/view/BG_U_2026_7380)

The results provide a basis for new collaborations with international research institutions, further system optimization and scale-up, and the continued development of the technology towards future practical applications.

This material was created with the financial support of the European Union through the “NextGenerationEU” instrument. All responsibility for the content of this document lies with the Institute of Solid State Physics – BAS, and under no circumstances can it be considered to reflect the official position of the European Union and the Monitoring and Reporting Structure to the Bulgarian Academy of Sciences.

Head of the research team: Assoc. Prof. Dr. G. P. Yankov

Team members:
Assoc. Prof. Dr. E. Iordanova

Chief Assistant Prof. Dr. V. Atanasova

Electronics engineer R. Stefanov

Assoc. Prof. Dr. Valentin Mihaylov

Chief Assist. Prof. Dr. Georgi Marinov