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The process of extracting lipids from high-moisture Scenedesmus quadricauda microalgae biomass disrupted with microwave was examined. The study showed that microwave pre-treatment is effective in algae cell rupture while microwave power was found to be a significant factor to enhance the degree of cell disruption. Though microwave pre-treatment time had some effect, the degree of cell rupture seemed to decrease after a certain pre-treatment time. The total lipid from Scenedesmus quadricauda sp. were extracted using a mixture methanol and sulphuric acid as an organic solvent. In addition, it was discovered that microwave pre-treatment enhances the disruption of microalgae cells to attain a high level of lipid yields. Optimal lipid yield obtained in this study was 49% at power 600 W, heating time of 8 min and extraction time of 3.5 h.

In order to increase the methane yield from biomass, this paper investigates the mechanical pretreatment effect of a Hollander beater on the anaerobic digestion process of Pelvetia canaliculata macroalgae using a response surface methodology (RSM). Higher values on methane yield were obtained at lower F/I ratios, with an increase up to 2.5-fold at an F/I value of 0.3. A multi-objective optimization study was carried out with the aim of maximizing the methane yield while minimizing the pretreatment time. An optimum methane yield of 283 ml/gVS was obtained for 50 min pretreatment time and a ratio F/I of 0.3, which represents an increase of 45% compared to non-pretreated algae.