Cultivation of microalgae in organic media and effect of wavelengths of lights on growth

The main goal of this study was to extract nutrients from two types of seaweed, firstly Laminaria digitata and also Ascophyllum nodosum, to use as an organic medium for growing microalgae A. platensis more commonly known as spirulina. Extraction was done with water, and filtered. To get information on which concentration of seaweed versus water suits for the culture, different amounts of concentration was studied by following the growth of the cultivation in organic media made from concentrated seaweed extraction and also with nutritional analysis. A. platensis was grown in 2 L cultivation unit in organic media and in organic media with organic certified nitrogen and phosphate added, that was compared to growth in inorganic media. This study revealed that A. platensis grew in organic media and density was within range in organic media compared to inorganic media where the difference was not significant with ANOVA analysis in density according to dry weight measurements. Biomass from cultivation was freeze dried and measurements on percentages of the c-Phycocyanin (cPC) content was done. Measurements showed lower percentages of cPC content in microalgae grown in inorganic media compared to organic media. This study showed that there is a possibility of using liquid seaweed extraction as nutrients to grow microalgae. Two types of light sources were compared with different wavelengths of the blue and red lights. The cultures were cultivatied in cultivation units (220 L), where growth and concentration of cPC content were measured over 8 days. The experiment were repeated three times and results showed significant difference (according to ANOVA analysis) in density between different light sources, resulting in faster increase in growth rate of microalgae grown with light source A compared to light source B. Concentration of cPC in biomass between the two light sources resulted in 1-2% higher cPC content in the biomass grown with light source B compared to light source A