Sub and supercritical water extraction of valuable products from algae

Laufzeit
01.09.2015 - 01.09.2018

Microalgae is considered as a promising substitute resource for both energy and human health, as they contain high amount of carbohydrates, proteins and lipids, while not grabbing arable land. The main concept is a hydrothermal bio-refinery. First the valuable substance will be extracted followed by residue converted by hydrothermal liquefaction and the process water treated by aqueous phase reforming. As the last step reaction water with nutrients should be used for the production of algae. In the whole process the reaction medium is water.

Contents
Microalgae is a rich source of carbohydrates, proteins, minerals, vitamins, oils, fats and polyunsaturated fatty acids (FUFAs), which are important food supplements. Production of algal extracts involving toxic organic solvents or aggressive extraction that could deteriorate biologically active compounds. Water in high pressure and temperature condition has a lower dielectric constant, which means it can work as a polar solvent. Sub- and supercritical water (critical point 374℃, 22.1MPa) is a feasible green solvent for algal extracts production.

Aims
By optimizing extraction conditions, the highest efficiency should be obtained while maintaining the functional properties of extracts. A selectivity of substance of different polarities will be reached by applying different temperatures and pressures around critical point.

Approach

• Pretreatment of selected algae samples
• mechanical, ultrasonic, chemical, enzymatically

Extraction process

• temperature, pressure, flow rate, modifiers
• kinetics of extraction
• evaluation of bioactive properties of extracts
• other mechanical factors affecting extraction efficiency