Lipase catalysed biodiesel synthesis with integrated glycerol separation in continuously operated microchips connected in series

•Integrated system for biodiesel synthesis with integrated glycerol separation was developed.•A conversion of 95% was obtained within residence time of 2 h.•Deep eutectic solvent was used to extract the biodiesel.•Purified biodiesel was produced with glycerol content under detection limit. Although the application of microreactors in different processes has been extensively explored in recent decades, microreactors continue to be underexplored in the context of the enzyme-catalysed process for biodiesel production. Due to their numerous advantages, microreactors could become the next step in the development of a biodiesel production process characterised by sustainability, cost-effectiveness and energy efficiency. In this investigation, biodiesel production was catalysed by lipase from Thermomyces lanuginosus (Lipolase L100). Edible sunflower oil was used as a model substrate in order to investigate the process. After optimal process conditions had been determined, waste-cooking oil was used for biodiesel production to make the production process more sustainable. Three different substrate-feeding strategies were investigated and finally an optimal strategy was proposed. In all the investigated systems, fatty acids methyl esters (FAME) content was higher than 95% and obtained in a significantly shorter time (less than 2 h) compared to the batch process in which biodiesel production was catalysed by lipase (C = 95%, t = 96 h). After the optimal biodiesel production system had been proposed, an integrated system with two microchips connected in series was developed. The first microchip was used for biodiesel production and the second for simultaneous purification i.e. glycerol separation. Finally, purified biodiesel was produced with glycerol content below the detection limit.