Deep eutectic solvent-based protein recovery from microalgal biomass grown in piggery wastewater

Microalgae are a promising alternative to address wastewater treatment while converting wastewater nutrients into valuable protein-rich biomass, providing a dual-purpose solution. This study investigates protein recovery from microalgal biomass based on Scenedesmus almeriensis cultivated in swine wastewater using deep eutectic solvents (DESs) and their water mixtures. The behavior of two DESs (choline chloride:urea and choline chloride:glycerol at a 1:2 molar ratio) was evaluated with varying amounts of water. Both DESs outperformed water in protein extraction, and adding water to the DES:biomass mixture improved recoveries. The impact of the experimental factors was evaluated using a factorial design. The highest protein yield (16.8 %) was obtained with DES ChCl:2Urea with 81.6 % of water, by milling discs, a 12:1 DES:biomass ratio and extraction at 30 °C by 0.5 h. Despite moderate yields, this work underscores the potential of aqueous solutions of DESs as green solvents for protein recovery from microalgae.