Home > Research at LGC > BioSyM - Bioprocesses and Microbial Systems > Research topics > Theme 4 : Biological depollution of contamined environments

Theme 4 : Biological depollution of contamined environments

Contact : Marion Alliet et Claire Joannis-Cassan

Expertise at the service of environmental conservation

- The studies carried out in this theme focus on the understanding and the optimization of biological treatment processes, applied to various effluents. Much of the work involves the use of membrane bioreactors for wastewater treatment. Classical notions of Chemical Engineering were used to optimize the biological reaction.
- Moreover, the aims of environmental conservation complement the profitability objectives of the depollution processes with toxicological certification of the treatments on the horizon.

Submerged membrane bioreactor for hospital wastewater treatment (pilot scale).

Understanding and optimizing wastewater decontamination processes

- For Membrane Bioreactors, energy expenditure, mainly due to the actions taken to limit fouling remains an obstacle to their development. Two lines of research are being pursued to understand fouling and prevent it from happening.

  • Firstly, the development of a global simulator of membrane bioreactors that incorporates three model blocks: biological depollution, membrane clogging and the balances (mass energy) for the overall process. This enables optimization of the syncopated filtration mode and of aeration management for fouling limitation resulting in energy saving (PhD: Yusmel Gonsalez Hernandez, 2013-2016) [1].
  • In addition, more specific studies to understand the mechanisms underlying fouling have accelerated their modeling (studies carried in the research framework FERMAT FR-CNRS 3089 INPT): sludge rheology (Region project, post-doc J. Günther, 2009-2010), evaluation of mean shear stress assessed in sludge around the membrane module (1 Pa, an order of magnitude greater than that usually found for water; PhD: E. Braak, 2009-2012, Léopold Escande Award) [2], effect of this stress on the sludge properties affecting the clogging (particle diameters, soluble microbial product concentrations).
    - Several projects concerning the elimination of anti-cancer drugs from wastewater by membrane bioreactor treatment have placed the department at the forefront of research in the domain. The feasibility of the process and the elimination of 75% of the drugs present were demonstrated during the ANR project coordinated by the team TOXEAUBAM (2006-2009 PhD: of L. Delgado, 2009: laboratory scale and semi-synthetic effluent).

Hydrodynamics around a membrane bundle. Photos of bubbles in sludge, in water and the computational fluid dynamics (CFD).

- Part of the outcome of this work was the micropollutants elimination mechanisms (biodegradation and adsorption and the fate of these molecules in the sludge solid phase was studied during the ANR project Jeune Chercheur BioMedBoue (Young Researcher BioMedSludge) coordinated by the department (2009-2013; PhD: J. Seira, 2013). Owing to the development of analytical methods to quantify low concentrations of anti-cancer drugs both in the liquid and in the solid sludge phase, rigorous determination of the concentrations indicated that biodegradation is the main process contributing to their elimination (40%) while adsorption only accounts for 0.5%.
- Currently, as part of the ANR project CD2I PANACEE 2010 -2015, coordinated by the department, these results have been extended to an experiment on a hospital site and on a semi-industrial scale pilot plant (500L/d). Analytical approaches using geno-, cyto-and eco-toxicity support chemical quantification. Although toxicity was shown to be largely decreased, pharmaceuticals do not seem as refractory as detergents and other traces of hospital activity, themselves affecting the biological efficiency of the process. These studies should help future research to focus on bio-enhancement in the treatment of micropollutants.

Degradation of DNA used as a biomarker to evaluate the toxicity of effluent.