Lipid extraction from freshwater and marine microalgae using confined impinging jet mixer

Microalgae are capable of mitigating carbon dioxide emissions and producing highly productive oil with a potential for new generation biofuel applications. However, commercial scale production of biofuel from microalgae remains limited due to the highly energy intensive steps involved in the process. Additionally, there is a pressing need to explore sustainable alternatives to freshwater microalgae to alleviate environmental burden on scarce freshwater resources. Confined impinging jet mixer (CIJM) offers a process intensification approach for microalgal lipid extraction in a resource-efficient manner. The use of CIJM allows bypassing the energy intensive step of dewatering the diluted microalgae cultivated in open raceway ponds or photobioreactors. In this work, we perform a comparative investigation of lipid extraction from freshwater and marine microalgae using CIJM. The univariate experimental approach is adopted to examine the effect of process parameters including feed concentration, solvent to feed ratio on extraction. The extraction for freshwater microalgae is found to be more than three times of that yielded by marine microalgae. Multistage operation is shown to increase overall yield. The total lipid extraction at the end of three stage cascaded CIJM is 33% for freshwater microalgae and 13% for marine microalgae. The intensified technological approach demonstrated here holds promise to develop sustainable methods for microalgal lipid extraction.