Research on advanced proccesses

Sanni, I., Carabin A., Dirany A., et Drogui P. (2018). « Traitements électrochimiques des eaux usées industrielles : Un exemple de collaboration université-industrie« . Vecteur Environnement : Revue des spécialistes de l’environnement au Québec, vol. 51, no 1, p.30-32.

Yassine Ouarda, Bhagyashree Tiwari, Antonin Azaïs, Marc-Antoine Vaudreuil, Sokhna  Dieng Ndiaye, Patrick Drogui, Rajeshwhar Dayal Tyagi, Sébastien Sauvé, Mélanie Desrosiers, Gerardo Buelna, Rino Dubé (2018). « Synthetic hospital wastewater treatment by coupling submerged membrane bioreactor and electrochemical advanced oxidation process: Kinetic study and toxicity assessment« . Chemosphere 193, pp. 160-169.

In this work, the combination of membrane bioreactor (MBR) and electro-oxidation (EO) process was studied for the treatment of a synthetic hospital wastewater fortified with four pharmaceutical pollutants namely carbamazepine (CBZ), ibuprofen (IBU), estradiol (E-E) at a concentration of 10 μg L−1 venlafaxine (VEN) at 0.2 μg L−1. Two treatment configurations were studied: EO process as pre-treatment and post-treatment. Wastewater treatment with MBR alone shows high removal percentages of IBU and E-E (∼90%). Unlikely for CBZ and VEN, a low elimination percentage (∼10%) was observed. The hydraulic and the solid retention times (HRT and SRT) were 18 h and 140 d respectively, while the biomass concentration in the MBR was 16.5 g L−1. To enhance pharmaceuticals elimination, an EO pretreatment was conducted during 40 min at 2 A. This configuration allowed a 92% removal for VEN, which was far greater than both treatments alone, with lower than 30% and 50% for MBR and EO, respectively. The MBR-EO coupling (EO as post-treatment) allows high removal percentages (∼97%) of the four pharmaceutical pollutants after 40 min of treatment at a current intensity of 0.5 A with Nb/BDD as electrodes. This configuration appears to be very effective compared to the first configuration (EO-MBR) where EO process is used as a pre-treatment. Toxicity assessment showed that the treated effluent of this configuration is not toxic to Daphnia magna except at 100% v/v. The MBR-EO coupling appears to be a promising treatment for contaminated hospital effluents.

Hospital wastewaters, Pharmaceutical pollutants, Electrochemical advanced oxidation process, Membrane bioreactor, Daphnia toxicity test

Combinaison des procédés d’électrocoagulation et d’électro-oxydation pour le traitement des eaux usées résiduaires issues des opérations de nettoyage de cuves industrielles

Master thesis of Isbath Sanni

Research advisor : Patrick Drogui

Industrial wastewaters are generally characterized by complex and diverse pollutants. This makes them difficult to treat them by conventional biological processes. Therefore,It becomes a priority to develop innovative and efficient processes for the treatment of a wide range of pollutants. Electrochemical processes such as electrocoagulation (EC) and electro-oxidation (EO) have recently proved their effectiveness for the treatment of industrial refractory matrices. These processes are simple to operate and do not require the addition of chemicals reagents. The purpose of this project was to combine EC and EO for the treatment of highly contaminated wastewater (Chemical Oxygen Demand COD of 10 360 ± 665 mgO2/L and an initial concentration of phosphorus of 22.9 ± 0.9 mg/L), from industrial cleaning tanks in order to meet sewer discharge standards. After a characterization step (1) the EO was tested then (2) the EC and finally (3) the coupling EC-EO. Indeed, EC was used as a pretreatment method to remove suspended solids, fine colloidal particles and total phosphorus (Pt) while EO was chosen for its ability to directly and indirectly oxidize refractory organic contaminants. Thus, for the EO, different operating parameters were investigated such as the type of anode (boron-doped diamond (BDD), iridium dioxide (IrO2) and mixed-metal oxide (MMO), the current density (0.05 to 0.23 A/cm²), the amount of electricity (0 to 122 Ah/L) while for the EC the current density varied from 4.5 to 13.6 mA/cm² and the amount of electricity from 0 to 3.06 Ah/L. With regard to the EO process, the best COD abatement rate was obtained with BDD (91 ± 4.9%) versus 52 ± 7.3% for other anodes. Despite a significant removal of COD, the EO alone did not allow the removal of total phosphorus and colloidal particles. The combination EC-EO allowed 97% of phosphorus removal while 95% of COD was removed to meet the sewer discharge standard. Moreover, the EC-EO coupling reduces operating costs to 7.3 $CAD/m³ against 24 $CAD/m³ when the EO process is used alone.