BioSym: Biologic depollution and valorisation of effluents

The objectives of the research under this theme are to improve the understanding and implementation of biological treatment processes for effluent treatment, particularly for wastewater.

The developed approaches developed aim at (i) developing innovative processes for the treatment of effluents and their energy recovery (ii) directing the control of bio-reactions and the optimization of reactors towards the elimination of micropollutants, integrating chemical, ecotoxicological and microbial characterizations, (iii) optimizing bioprocesses through experimental approaches, from laboratory scale to actual site scale, and the use of digital tools.

Valorization of effluents to reduce their economic and environmental impacts

Bioelectrochemical processes are investigated for reducing wastewater treatment costs (suppression of the aeration of wastewater treatment plant tanks). A distinction is made between passive treatment based on the bioelectrochemical snorkel process (ANR biotuba) and treatment based on the microbial electrolysis process that produces hydrogen (WE-MET Project). The large-scale deployment of these bioelectrochemical processes could allow, in the long term, the construction of wastewater treatment plants that are at least autonomous, or even exceeding their energy requirements. The hydrogen produced could be used to produce electricity (domestic, industrial or automotive fuel cells) or heat (by combustion).

Optimization work has been carried out in recent years in LGC independently on the technological building blocks of bioelectrochemical processes (anode, cathode, electroactive biofilms, membrane, fluidic…) and then combined to design a 15 L microbial electrolysis cell demonstrator. This demonstrator is to be installed within the Hydrogen platform on the Toulouse INP campus. The next objective is to adapt the technology to the treatment of industrial wastewater from the agro-food, textile and tannery sectors, which are more contaminated with chemicals, heavy metals and recalcitrant pollutants.

Micropollutants degradation

After initial tests in synthetic solutions and laboratory units (Delgado Thesis 2009), we demonstrated that membrane bioreactors (MBRs), under specific operating conditions, are good candidates for the elimination of organic micropollutants (MP). Even in real-life situations (ANR PANACEE (2011-2015) and Projects Onema -SMS and REMPAR (2015-2019)), MBRs systematically lead to an abatement of toxicological effects (eco-geno) or endocrine disruptors while MPs are still present. Today we are interested in the kinetics of emergence and effects of the transformation products of these molecules (ANR TRANSPRO 2019-…) and the implementation of coupled processes for an optimized treatment according to the uses of the treated water (SUDOE INNOVEC’EAU). We are also interested in the capacity of the purifying biomass to degrade these MPs under stress: Thus, we obtained remarkable MP abatements by a tertiary process with immobilized biofilm MBBR (moving bed biofilm reactor) for which the mechanisms are being elucidated (Abtahi et al, 2018). This questioning also comprises a study on an aquaponics system with biofiltration water treatment.

Visualisation of aeration path in a section of MBR by ERT

Optimisation des procédés biologiques de traitement de eaux usées

Wastewater treatment processes can be optimised for abatement performance, sludge reduction  (Minerva project), chemical inputs or energy consumption (Mocopée I & II). To this end, modelling approaches and simulation tools are developed: knowledge-based modelling of biological reactions under original conditions (presence of drugs, predators, very large processes, etc.), this modelling coupled with filtration modelling, statistical modelling by fuzzy logic.

These approaches are associated with experiments, and even with the development of new experimental methodologies: electrical resistivity tomography (ERT) for the study of hydrodynamics, statistical analysis of the morphology of flocs. The whole approach (experimental and digital) drives the understanding of the phenomena involved in these processes forward and progresses thanks to this understanding.