Investigation of four microalgae in nitrogen deficient synthetic wastewater for biorefinery based biofuel production

Microalgae are a possible source of biofuel, but no commercial development has yet been developed. Possible approaches to improve economic feasibility involve increasing lipid content and the usage of biorefinery in microalgae. In this regard, the nitrogen-deficient-synthetic wastewater was fed to four microalgae to increase the lipid and carbohydrate content. In conjunction, changes in the amount of biorefinery components, including proteins and pigments, during nitrogen synthetic wastewater feeding have also been reported. The study revealed that both lipids and carbohydrates increased as much as 2 and 1.5 times in selected microalgae after 20 days of nitrogen-deficient-synthetic wastewater relative to nitrogen sufficient conditions, respectively. In particular, after 20 days of exposure to nitrogen deficient synthetic wastewater, the highest Lipid content of 40% was displayed by Desmodesmus sp. The same species had also shown an increased carbohydrate content of 18.3%. Carotenoids was retained in Desmodemsus sp. (0.03%) through nitrogen deficiency, but were shown to be reduced in three other algae. Analysis of the FAME profile of four nitrogen-deficient microalgae indicated that lipid was promising for biodiesel production as it showed an increase in saturated fatty acid content and a decrease in unsaturated fatty acid content. However, during nitrogen insufficiency, unavoidable side reactions involving reductions in protein levels, chlorophylls (a and b type) and biomass were observed in all four microalgae. But 23.3% protein was found in Desmodesmus sp. at end of 20^th day of nitrogen deprivation The study showed that feeding of nitrogen-deficient-synthetic wastewater raised the lipid and carbohydrate content and maintained carotenoids in selected microalgae. Above said approach is possibly a low cost economical option for biorefinery.