Although promising, the microbial electrosynthesis concept is only few years old. The consortium is well‑aware that the associated technology is not mature. The underlying idea of the project is therefore to take a strong position in this field by acquiring knowledge in order to prompt future innovations and associated industrial developments. Our objective is to establish a detailed framework for the implementation of BES technologies for waste biorefinery. On the basis of scientifical, technical, environmental and economic knowledge acquired during the project, we identify key components and associated specifications for the elaboration of a future industrial development strategy.
Narrowing the scope of potential industrial application of bioelectrosynthesis for waste biorefinery requires several interconnected issues to be handled in an integrated approach.
WP1 – Determining cathode operating conditions for microbial electrosynthesis
After defining and analyzing the theoretical cathode settings related to the synthesis of different molecules, the experimental evaluation starts with simplified experimental settings allowing well-controlled electrochemical conditions at the biocathode (three electrode systems with abiotic anode). The main objective is to study the influence of operating parameters at the cathode (cathode potential, pre-selected inocula, pH, temperature) on the type and kinetics of the products formed. The WP1 considers a first bioconversion step consisting in using CO2 as a carbon source for the production of acetate. Then, strategies combining several biocathodes and/or biocathodes combined with fermentation steps are considered for elaborating more complex added value organic products.
WP2 – Understanding and optimizing electrochemical performances
The first objective is to optimize electrochemical performances by trying to maximize current densities. This work is conducted at the anode and at the cathode. Different waste hydrolysates are tested at the anode. The influence of cathode configuration (electrode material, electrode geometry) is also studied.
WP3 – Operating and evaluating a labscale BES for waste derived microbial electrosynthesis
The objective is to set up basic labscale configurations with both biological anode and cathode. The anode input consists of waste hydrolysate selected according to the results of WP2. First, a single cathodic compartment fed with CO2 is included on the basis of the results obtained in WP1 and WP2. This configuration is operated and evaluated in terms of electrochemical and metabolic (using stable isotopes) performances. A model (under COMSOL Multiphysics® environment) of the BES is developed. Microbial community analysis using modern high throughput tools are performed both at the cathode and the anode. Then, more complex configurations including a cathodic network are set up, operated and evaluated.
WP4 – Identification of environmentally sensitive parameters and benchmarking of the BIORARE concept
Fictitious but realistic scenarios leading to the definition of a reference perimeter for Life Cycle Assessment (LCA) are defined with all partners. A sensitivity analysis of selected parameters is performed allowing the early identification of environmentally sensitive components that may in turn contribute to the technical (WP1, WP2, WP3) or industrial (WP5) discussion.
WP5 – Industrial strategies for the implementation of the BIORARE concept
The economic and regulatory components are taken into consideration. Societal analysis as well as more detailed effective integration of the BIORARE reactor into existing industrial settings is studied. WP5 aims at refining, rationalizing and optimizing the coupling between BES technology and all elemental and energy fluxes available within existing waste treatment facilities (here the coupling with an anaerobic digestion treatment is depicted).
