Upstream bioprocessing of Spirulina platensis microalgae using rainwater and recycle medium from post-cultivation for C-phycocyanin production

Background

The cultivation of microalgae represents a water-intensive process, prompting the need to reduce its water footprint and explore alternative water sources. Therefore, this research work aims to investigate the growth of Spirulina by recycling the culture medium obtained from the post-cultivation process and substituting rainwater resources for the preparation of the culture medium.

Methods

The effect of pre-treatment methods, specifically microfiltration and UV-light was investigated. These methods were applied to treat the recycled medium and rainwater resources used for Spirulina cultivation. Biomass concentration, biomass productivity and phycocyanin accumulation of Spirulina were examined to assess the Spirulina growth under different pre-treatment conditions.

Significant Findings

After three cultivation cycles in the recycled medium, biomass productivity decreased from 0.2246 to 0.0802 g/L/d which might be due to high salinity and biological pollutants that inhibit Spirulina growth. However, different pre-treatment methods using microfiltration and UV-light on the recycling medium were found to be effective in increasing biomass productivity from 0.1395 to 0.1861 g/L/d. Additionally, the use of rainwater for Spirulina cultivation was explored. Applying pre-treatment methods to the rainwater, biomass productivity was further improved from 0.3211 to 0.3837 g/L/d. These findings suggest that the use of pre-treatment methods and alternative rainwater resources can improve the biomass productivity of Spirulina and potentially reduce the environmental impact throughout the microalgae cultivation process.