Enhancing the biomass production of microalgae by mixotrophic cultivation using virgin coconut oil mill effluent

Skim is a major by-product of the virgin coconut oil (VCO) industry consisting of nutrients and is currently discharged to the environment as waste. Hence, this research aimed to utilize skim as a medium for Botryococcus braunii and Chlorella vulgaris growth. The effect of organic carbon resourced from glucose and glycerol on biomass was also investigated at certain concentrations with intervals 100:0 to 0:100 (%). Results indicated that Botryococcus braunii and Chlorella vulgaris cultivated under 20% VCO mill effluent gave the highest biomass production, which accounts for 1.69 g/L and 5.34 g/ L; 89.40% and 86.70% COD reduction efficiency. Whereas, mixotrophic condition showed a positive trend for Botryococcus braunii at 80:20 (glucose:glycerol) with 5.60 g/L biomass production and 97.64% COD removal efficiency. Vice versa, the addition of glucose:glycerol gave an inhibitory impact on Chlorella vulgaris as the biomass production was merely 1.66 g/L with COD efficiency 94.03%.