The effect of low-temperature pretreatment on the solubilization and biomethane potential of microalgae biomass grown in synthetic and wastewater media

•C. vulgaris and native algae were grown in sterile and non-sterile media.•Methane production from native microalgal biomass was 154-252 L CH4 kg−1 VS.•Low-temperature pretreatment at 80 °C increased the biomethane potential by 11-24%.•The differences in the BMP and solubilization originate from cultivation media.

Microalgae have been suggested as a sustainable raw material for biofuel production in the form of methane via anaerobic digestion. Here, pretreatments at 60-80 °C were investigated, aiming to study the impact of algae culture media on biomethane potential and pretreatment efficiency. Chlorella vulgaris and mixed culture of native algae species (dominating by Scenedesmus sp.) were grown in synthetic medium, wastewater (sterilized and non-sterilized) and digestate from anaerobic digestion of pulp and paper biosludge (sterilized and non-sterilized). The biomethane potential for native microalgal biomass varied between 154 and 252 L CH4 kg−1 VS depending on culture media. The efficiency of the low-temperature pretreatment (80 °C, 3 h) for solubilization (9-12%) of C. vulgaris and native algae biomass was similar for algae grown in sterilized and non-sterilized wastewater media. The pretreatment increased the biomethane potential of native algae biomass by 11-24%.

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