Steam Explosion and Vibrating Membrane Filtration to Improve the Processing Cost of Microalgae Cell Disruption and Fractionation

Abstract

The aim of this study is to explore an innovative downstream route for microalgae processing to reduce cost production. Experiments have been carried out on cell disruption and fractionation stages to recover lipids, sugars, and proteins. Steam explosion and dynamic membrane filtration were used as unit operations. The species tested were Nannochloropsis gaditana, Chlorella sorokiniana, and Dunaliella tertiolecta with different cell wall characteristics. Acid-catalysed steam explosion permitted cell disruption, as well as the hydrolysis of carbohydrates and partial hydrolysis of proteins. This permitted a better access to non-polar solvents for lipid extraction. Dynamic filtration was used to moderate the impact of fouling. Filtration enabled two streams: A permeate containing water and monosaccharides and a low-volume retentate containing the lipids and proteins. The necessary volume of solvent to extract the lipids is thus much lower. An estimation of operational costs of both steam explosion and membrane filtration was performed. The results show that the steam explosion operation cost varies between 0.005 $/kg and 0.014 $/kg of microalgae dry sample, depending on the cost of fuel. Membrane filtration cost in fractionation was estimated at 0.12 $/kg of microalgae dry sample.

Isolation of Industrial Important Bioactive Compounds from Microalgae

“…Other techniques such as enzymatic extraction, supercritical extraction, ultrasonic-assisted extraction, microwaves are used to facilitate lipid extraction by solvent [ 113 ]. Nevertheless, only a few cell disruption techniques feasible for commercial application, namely, steam explosion [ 114 ], enzymatic hydrolysis, bead milling and horn sonication [ 113 ]. Purification of algal oil (PUFAs) is an essential step as the crude form of these oils are inedible due to its impurities, odour, taste and unattractive for consumption as its turbid appearance.…”

Current and novel approaches to downstream processing of microalgae: A review

“…Cell wall disruption via hydrolysis is variably referred in the literature as water bath treatment (McMillan et al, 2013), autoclave (Florentino de Souza Silva et al, 2014), hydrothermal pretreatment (Xiao et al, 2019) and steam explosion (Lorente et al, 2018). In all these variations two main mechanisms are thought responsible for the microalgae cell disruption; cell wall rupture due to internal pressure buildup from the heating, and hydrolysis of cell wall components.…”

Isolation of Industrial Important Bioactive Compounds From Microalgae: A Review

“…Other techniques such as enzymatic extraction, supercritical extraction, ultrasonic-assisted extraction, microwaves are used to facilitate lipid extraction by solvent [116]. Nevertheless, only a few cell disruption techniques feasible for commercial application, namely, steam explosion [117], enzymatic hydrolysis, bead milling and horn sonication [116]. Purification of algal oil (PUFAs) is an essential step as the crude form of these oils are inedible due to its impurities, odour, taste and unattractive for consumption as its turbid appearance.…”