Potential of using organic fertilizer to cultivate Chlorella vulgaris for biodiesel production

Cultivating microalgae at industrial scale for biodiesel production required substantial amount of mineral fertilizer, typically nitrogen and phosphorus. In fact, the production of mineral fertilizer implies the usage of energy and fossil fuels resulting to unsustainable practise in a long term. On the other hand, organic fertilizer which is derived from food waste, biomass or manure also contains high value of nutrients that can support microalgae growth. Hence, in the present study, the potential of using organic fertilizer as an alternative nutrient source to cultivate Chlorella vulgaris was investigated. Under the supplement of organic nutrients, it was found that C. vulgaris grown favourably under the following conditions: initial nitrate content of 26.67 mg/L, 24 h of continuous illumination and pH of 5. Nevertheless, slow growth rate was observed when cultivating C. vulgaris under open environment; a reduction of 27% was recorded in comparison with controlled environment. On the other hand, it was possible to reutilize the water to re-cultivate C. vulgaris. This observation reflects the high adaptability of C. vulgaris towards the surrounding environment and suitability to be grown under outdoor conditions. Total lipid of 18.1% from C. vulgaris biomass was successfully extracted and the fatty acids methyl ester profile was proven to be suitable for making biodiesel.