Design and construction of an experimental modular flat plate air lifting Photobioreator for microalgae growth study and efficient high quality biomass production

Abstract

For more than 100 years microalgae have been used as a source of human food, fertilizers, animal feed and a variety of compounds and pigments of high added value for pharmacological, cosmetic and medicinal use. However, only in the last four decades, microalgae production has also become a potential renewable source of energy, used in biofuel production, fixation of greenhouse gases (CO2), production of Oxygen (O2) and Hydrogen (H2). From that point on, the interest in biotechnological knowledge about these microorganisms, as well as the most efficient means to make it growth efficiently, has started to attract the attention of governmental authorities, environmental protection agencies and also the commercial interest of companies worldwide. Currently, microalgae for energy production are cultivated through open and closed photobioreactors (PBR), the first being responsible for 80% of the total biomass produced. Although open PBRs are most popular by its low cost, the closed FBRs are the equipments with the greatest potential for the study of microalgae cultivation, as well as for the production of high quality biomass, both at the experimental and industrial levels. The main challenge for the design of a closed PBR is that it has a compatible cost versus operational characteristics such as its volumetric productivity (PV) - [gL-1d-1] and its productivity per illuminated surface of the reactor (PSI) [gm-2d -1], that in summary represents a high photosynthetic efficiency (FSE) usually expressed in [microEm-2d-1]. For instance, the herein proposed PBR, denominated EVONi PBR-FPA 7L, will be addressed for experimental use in research laboratories and biotechnology centers at the universities, being offered to the Brazilian market as a competitive choice when compared with its similar local and foreign competitors. Designed with a innovative split modular construction, the EBR-PBR-FPA 7L will have vertical flat plate geometry with multiple recirculation chambers and a bottom air + CO2 lift aspersion system for algae growth medium agitation. The reactor lighting will be initially artificial, made by a photonic system of LEDs (Light Emitting Diode), with the possibility in the future to migrate to sunlight source in models with greater illuminated area and volumetric capacity. For robust development of the EBR-Ni PBR-FPA 7L, the biotechnological knowledge about the cultivation of the microalgae called Haematococcus pluvialis (Hp) will be adopted and supported by the researchers and technicians of the laboratory of Molecular Biotechnology of the Institute of Physics of São Carlos, University of São Paulo (IFSC-USP), who work at the Polo TErRA (Thematic Pole of Renewable Energies and Environment). This exchange of knowledge will allow the evaluation and validation of the PBR design, as well as its construction and experimental operation. In future stages, as a natural evolution of the development and commercialization of the EBR-Ni FBR-FPA 7L, the objective will be to consolidate the multidisciplinary knowledge acquired by the company and apply it to develop new PBRs, but now with larger production capacities and control capabilities, allowing microalgae cultivation processes through experimental pilot or industrial plants. (AU)