Development of a lightweight multi-skin sheet photobioreactor for future cultivation of phototrophic biofilms on facades.

This article covers the development of a novel emerse photobioreactor (ePBR), using a polycarbonate multi-skin sheet (MSS), to cultivate terrestrial cyanobacteria as surface-associated phototrophic biofilms in an aerosol-based cultivation process. The aerosol, generated by ultrasonic transduction, moistens and nourishes the biofilm inside the multi-skin sheet emerse photobioreactor (MSSePBR). Advantages of the MSSePBR, such as its low weight design and reduced water consumption due to the usage of aerosol, simplify the development for future facade bioreactors. To develop the MSSePBR, surface roughness, static contact angle and luminous transmittance were investigated to characterize the properties of the cultivation surface for phototrophic cultivation. The polymeric MSS showed good luminous transmittance and proofed its optical suitability for the cultivation of terrestrial cyanobacteria. Using the MSSePBR, the terrestrial cyanobacteria Coleofasciculus chthonoplastes and Trichocoleus sociatus were cultivated with either ambient air, air with increased CO2 content or flue gas. The cultivation of terrestrial cyanobacteria showed higher productivities for biomass in the MSSePBR than in suspended systems. Cultivation with increased CO2 contents and flue gas was possible, thus a combination with flue gas treatment is feasible. An up-scaled prototype of the MSSePBR was introduced to show the possibilities for future industrial-sized and facade applications.