Evaluation of wine lees ultrasonic cavitation as pre-treatment and its possible use as substrate for microalgae biomass production

Ultrasonic cavitation is a technology used to improve organic carbon solubilization of a substrate, increasing its biodegradability for further biological treatment. Moreover, its application has a pasteurization effect on waste stream. In this study, different cavitation times (5, 10, 20 and 30 min) are tested on white and red wine lees to evaluate the organic compounds solubilization, physical-chemical variation and antimicrobial cavitation effects, with the aim of further valorization with biotechnological applications such as microalgae growth. Wine lees cavitated effluents are applied as substrate for Chlorella vulgaris growth, obtaining a microalgae-yeast microbial community biomass of 2.4 ± 0.7 g L⁻¹ (WL) and 1.7 ± 0.0 g L⁻¹ (RL) with 33.9 ± 4.1 % (WL) and 60.5 ± 5.3 % (RL) of lipids content. Ultrasound cavitation is efficient in controlling native microorganism proliferation (yeast and mold) only applying at least 10 min of pretreatment. This pretreatment allows to change chemical-physical and microbiological properties of wine lees, that are compatible as organic substrate for microalgae cultivation in a circular economy approach.