Harvesting and pre-treatment of microalgae cultivated in wastewater for biodiesel production: A review

Global greenhouse gas emissions, primarily CO2, are projected to rise by 1.3% per year between 2005 and 2011.

“However, this shift has increased global greenhouse gas emissions, primarily CO2, which are projected to rise by 1.3% per year between 2005 and 2011 [1, 5].”

Complex and hard cell walls of microalgae can be broken down by mechanical, chemical, and enzymatic treatments, making it easier for solvents to penetrate and extract lipids.

“Furthermore, the complex and hard cell walls of microalgae can be broken down by a variety of mechanical, chemical, and enzymatic treatments, which makes it easier for solvents to penetrate and extract the lipids [5, 35].”

Combined enzymatic and mechanical/solvent-free extraction methods are more promising for lowering solvent usage and energy consumption for lipid extraction.

“A more promising approach includes combined enzymatic and mechanical/solvent-free extraction methods to lower solvent usage and energy consumption for extracting lipids efficiently [5, 39].”

Extreme reaction conditions like high alcohol-to-oil ratio and temperature are necessary for heterogeneous catalysts to accelerate the reaction.

“However, extreme reaction conditions like high alcohol-to-oil ratio and temperature are necessary for these catalysts to accelerate the reaction [5].”

The remaining factors, such as iodine value, viscosity, cetane number, cold properties, distillation temperature, and polyunsaturated fatty acid, are primarily determined by the fatty acid composition.

“The remaining factors, such as iodine value, viscosity, cetane number, cold properties, distillation temperature, and polyunsaturated fatty acid, are primarily determined by the fatty acid composition [5, 40].”