Etude et Optimisation du Couplage MicroAlgue-Bactérie Anaérobie pour la Production d’Energie par voie biologique à partir de biomasse primaire et de déchets organiques – SYMBIOSE

Our approach is based on the mechanisms observed in natural aquatic environments.
The selection of microalgal populations able to grow rapidly on the digestate
produced from anaerobic digestion was one of the main achievements. The
demonstration of interactions between microalgae and aerobic bacteria identified
optimized microbial consortia. Optimal conditions for anaerobic conversion of
selected biomass into biogas and macronutrients (N, P, K) have been identified, and
the expected performance in terms of energy and nutrients recycling were calculated.
The results from these two tasks have led to the design of mathematical models able
to represent and to optimise the biological mechanisms involved. These models are
also used to implement control strategies, and for scaling up the industrial process.
The analysis of the coupled system and the perspectives for industrials applications
are supported by a Life Cycle Assessment study.
Finally all the concepts developed were tested on a pilot associating culture of
phytoplanktonic biomasses and anaerobic digestion at the laboratory scale and pilot
plant at pre-industrial scale (pond of 60 m2 and 1 m3 digester).

Among the major results of the project, the cultivation of microalgae on a digestate and the methanisation of these organisms have been demonstrated to be feasible and for a wide variety of microbial consortia. Results obtained on anaerobic digestion of microalgae allowed us to identify the limiting steps of this process and the optimisation strategies. The modeling led to the identification of optimal conditions for production of energy and nutrient recycling. Environmental impacts associated with industrial perspectives were evaluated and the processes which revealed the greatest impacts were identified. The implementation of two coupled systems at the laboratory, pilot and pre-industrial scale was a significant step, which offers new perspectives of investigations on the fundamental aspects and industrial applications.

.

- 20 oral presentations in national and international conferences
- 14 articles were published in peer review international journals
- One patent was registered on a method of coupling anaerobic digestion and culture of microalgae.