Biocircular platform for third generation biodiesel production: Batch/fed batch mixotrophic cultivations of microalgae using glycerol waste as a carbon source

The green microalga, Scenedesmus incrassulatus PPAY1 was cultivated in vertical tubular photobioreactor under batch/fed-batch modes. Biodiesel derived glycerol waste (BDGW) was applied as a cheap main nutrient source. For batch cultivation (BC), maximum biomass concentration was reached at 2.83 gL-1when 20 gL-1 BGW was used. In contrast, in the case of fed-batch cultivation (FBC), the maximum algae and lipid contents were achieved at 5.65 gL-1 and 58.27%, respectively when 30 and 20 gL-1 BDGW were applied. The highest lipid yield of 2.94 gL-1was found at 30 gL-1 BDGW. The analysis of the fatty acid content revealed that palmitic acid-, oleic acid- and linoleic acid- were mainly found in both BC and FBC conditions. As expected, FBC was in a better culture strategy than BC. BDGW could be used directly without any pretreatment in both algal biomass growth and microalgal oil accumulation which simplifies cultivation and reduces operating costs during biodiesel production.