Design and fabrication of a simple and cost-effective microalgae culture photobioreactor and optimization of culture conditions

In connection with the cultivation of microalgae, the type of photobioreactors is one of the major parameters that should be considered as it directly affects the economy and efficiency of the process. In this study, a new design and fabrication of a microalgae culture photobioreactor using a plastic bag were performed. The performance of the photobioreactor was enhanced, and technically evaluated through tests such as stability, physical strength, light penetration rate, mass transfer rate, temperature control and mixing. The experimental results on plastic photobioreactors indicated that the main issues were related to the aeration and mixing in the system. To address this problem, an airlift pump was designed and installed at the end of the photobioreactor. The performance of the photobioreactor in the production of microalgae biomass was tested using the municipal effluent of Malek Ashtar University as a culture medium and inoculation of Chlorella vulgaris species. To optimize the culture conditions of microalgae, three factors: urea, phosphate, and baking soda concentrations were considered. The results showed the relationship between carbon, nitrogen, and phosphorus sources in increasing the cellular content of microalgae, which in the minimum amount of organic carbon source, with increasing the concentration of nitrogen and phosphorus, cell biomass production increases significantly. Accordingly, the production of more than 14 g/l of biomass in the amount of 0.9 g/l of baking soda, 0.25 g/l of urea, and 0.5 g/l of phosphate was obtained..