The work carried out during the project to achieve the RO was organized based on four interconnected work packages (WP). As described in the project proposal, each WP included various tasks to help achieve the four different RO of the project. WP1: Design and operation of a CO2-MCM prototype. Work focused first on the evaluation of different CO2 adsorbent materials by impregnating fumed silica (FS) with polyethylenimine (PEI) of different molecular weights. From these experiments, the most suitable material composition to perform indoor CO2 capture was obtained and thus this composition was selected to be used within the CO2-MCM prototype. Along the project, up to three CO2-MCM prototypes were developed, with different degrees of automation at different degrees of miniaturization. The last prototype was built in a single box, containing all the instrumentation to operate autonomously as well as the capture module containing the adsorbent material. WP 2: Determine the optimal conditions for steering gas bio-electro-fermentation towards selective production of hexanol. Tasks around this WP focused on the optimization of bioelectrochemical system towards selective production of biofuels, specifically methane. Methane was selected as a suitable biofuel to be produced bioelectrochemically using CO2 from indoor environments over other biofuels such as ethanol and hexanol, as originally described. Several experiments were carried out to assess the effect of operating variables (liquid and gas hydraulic residence time) over methane conversion and productivity rate. Tests also focused on the evaluation of the carbon needs to evaluate the feasibility of the coupling of CO2-MCM within the microbial electrosynthesis module (MESM). Results demonstrated the importance of the selection of a suitable liquid renovation rate as well as the minimum CO2 requirements to sustain a proper methane conversion within the MESM. This was useful information for the coupling of the capture and bioconversion module. The evaluation of the coupling of the microbioreactor module (MBM), by coupling of capillary microreactors was tested to reduce gas-to-liquid mass transfer limitation within the MESM. Results demonstrated that methane conversion was increased by 25 % as compared to when the microreactor was not in use. WP 3 Set up a MICRO-BIO process prototype to demonstrate the optimized process operation for hexanol production. Tasks around WP3 were carried out since the beginning of the project, as when each module was designed, it was designed taking into consideration how to integrate this module with the rest of the modules. The CO2-MCM module was the only module automated, while the MESM together with the capillary reactor module were operated semi-automatically, Instead, to assess the different synergistic relations between the modules, off-line coupling of the modules was performed, which means all three modules were operated in continuous mode, but they were not physically connected. One important milestone achieved along the project was the evaluation of the CO2-MCM within real environments at the Jacobs office in Bristol. This allowed us to demonstrate and evaluate the capability of the prototype to capture CO2 within a real environment. WP 4 Management, training, exploitation, and dissemination activities. Definitively this WP was one of the most active along the entirety of the project, as multiple activities were performed to manage, exploit, and disseminate the project. Because of the nature of the project (indoor air), the project captured great attention from the public (schools, non-expert public, professional sector, stakeholders) and thus we were invited to several activities (conference talks, school talks, radio, TV, press) to disseminate the project. Training activities were also carried out such as a training course in Delft University. At the same time, multiple meetings were carried out with the supervisory committee to assess the progress of the project and to plan the next steps.
