Enhanced lipid accumulation of Chlorella vulgaris with agricultural waste under optimized photoheterotrophic conditions

The study reports the usage of carrot pomace on lipid accumulation of Chlorella vulgaris in photoheterotrophic conditions for biodiesel production. The important parameters which effect lipid accumulation and transesterification reaction were optimized. The addition of 0.5 g/L carrot pomace sugar caused 1.38 times higher microalgae growth and 2.07 time higher lipid concentration when compared with the photoautotrophic conditions. The highest lipid accumulation was observed as 44.8% under nitrogen limitation and photoheterotrophic conditions supplemented with 0.5 g/L pomace sugar. The highest C16 + C18 fatty acid methyl ester (FAME) content was determined as 95.1% by in situ transesterification in a very short time and moderate temperature such as 30 degrees C among the tested approaches. It can be concluded that most fuel properties of synthesized methyl esters were found to well match with ASTM D6751 and EN 14,214 standards. To the best of our knowledge, this is the first report about the effect of carrot pomace hydrolysate on microalgae growth and lipid accumulation in photoheterotrophic conditions for biodiesel production.