Anaerobic digestion of microalgae in a circular economy approach with the Algotech project

With the current socio-economic and energetic context, developing new biotechnologies in food and biofuel field has never been crucial. Microalgae are a polyphyletic group and a huge pool of biological diversity 1. The Algotech project aims to develop the use of microalgae, particularly in the chemical, phytopharmaceutical and energy fields in a circular production route. Financial limits are known to be the most critical point during the process of setting up and marketing the products generated by microalgae, in particular because of the high cost of harvesting, drying, extraction and their maintenance. Thus, to respect the spirit of the circular economy promoted by the Algotech project, anaerobic digestion of microalgal residues (with potentially other co-substrates) will be used. In fact, large scale cultivation of microalgae to produce high added value components or biofuels implies production of large amount of biomass residues after their utilization. The anaerobic digestion of microalgae is a prospective environmentally feasible option and a key unit process for creating a renewable source of energy for industrial and domestic needs 2. Therefore, different challenges will be tackled such as the low C/N ratio and ammonia inhibition and the selection of the most suitable substrate to enhance the biogas production will be discussed.