WAEster

Winner of the 2024 call for projects.

For the bio-economy to be circular, biowaste needs to be properly treated and recycled into useful products via environmental biorefinery (EB) processes. While the use of microalgae is currently prohibitive for lower added value applications, their implementation in EB processes is a promising alternative to decrease production costs of renewable microalgal biomolecules.

However, further technological innovations are still needed: 

• At the level of cultivation, harvesting, fractionation, functionalization and separation of the components of the microalgal biomass to optimize the entire transformation process.
• In addition, co-valorization of molecules and recycling of process effluents is essential to increase added value and sustainability.

In this context, the WAEster project proposes to explore an integrated EB process that couples:

• Microalgae cultured on untreated waste fermentation effluents to the production.
• Separation of fatty acid ethyl esters (FAEEs).

The process aims to recover and valorize a maximum of microalgae constituents and process effluents in a minimum of steps and with minimal energy consumption, in order to reduce cost.

The WAEster project aims at incorporating primary validated production and conversion stages into a complete circular EB process, completing the cycle by the study and development of adapted downstream processing (DSP) steps.

Key steps and methodology:

Parameters of microalgae cultivation in photobioreactors (PBR) such as light, organic loading rate and retention time, and the link between the lipid profile of the biomass and the FAEE yield of the transesterification process will be deepened in order to understand and drive a stable process, and optimize FAEE productivity.

The crucial step of biomass harvesting will be addressed using flocculation/flotation, a very low energy and efficient separation process that causes minimal stresses on the biomass, which can in turn positively impact in situ lipid functionalization.

Membrane filtration processes will be studied to purify the FAEEs without the use of organic solvent, and, depending on their composition, to recycle the liquid and solids residues that arise during the process.

To ensure the circularity of the process, systematic characterization of the solid and liquid fractions generated along the way will be necessary to adapt and optimize co-products valorization and waste recycling. For example, residual fractions generated will be evaluated for recycling in the dark fermentation phase.

Each step will be first investigated and optimized at the laboratory scale to arrive at level 4 on the Technology readiness level scale, a proof of concept of the entire process. To reinforce this proof of concept, the process will subsequently be scaled up by an order of magnitude (10L PBR) to achieve a FAEE production at the gram scale, and thus pave the way for further exploitation of the WAEster process in collaboration with members of the private sector.
 

Project lifetime:
 

2024 - 2029

Scientific managers:
 

Robert Van Lis (INRAE) and Maeva Subileau (Institut Agro Montpellier)