Février, 2022

04feb15 h 00 min18 h 00 minSoutenance de thèse Marcos Oliveira Filho

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Détails

La soutenance de thèse de Marcos Oliveira Filho intitulée « Mechanisms of degradation under operating conditions of polymeric filtration membranes used in membrane bioreactor »

Aura lieu le vendredi 4 février à 15h dans l’amphi Concorde bâtiment U4 à L’Université Paul Sabatier

Pour celles et ceux qui ne peuvent pas venir sur place, il vous sera possible si vous le souhaitez d’assister en distanciel en vous connectant au lien Zoom ci-dessous :

https://univ-tlse3-fr.zoom.us/j/92422461860?pwd=NmpGNkYzcU01c0hwZWdHVFRnemF3QT09

ID de réunion : 924 2246 1860

Code secret : 473007

Membres du Jury :

  • Mme Catherine FAUR, Rapporteure
  • Pierre BERUBE, Rapporteur
  • Christophe DAGOT, Examinateur
  • Mme Murielle RABILLET-BAUDRY, Examinatrice
  • Mme Christel CAUSSERAND, Directrice de thèse
  • Yannick FAYOLLE, Co-directeur de thèse

Résumé :

While membrane bioreactors (MBR) have been broadly applied to wastewater treatment, membrane ageing studies focused mainly on: i) understanding the chemical action of sodium hypochlorite or ii) following ageing in drinking water facilities. Thus, a comprehensive study under full-scale MBR operating conditions is still required. The present thesis aim to: (i) understand the chemical action of sodium hypochlorite to commercial polyvinylidene fluoride (PVDF)/Polyvinylpyrrolidone (PVP) hollow fibers used in MBRs; (ii) Describe membrane ageing of these membranes in urban wastewater full-scale MBR based on characterization of harvested membranes and full-scale process indicators. For this, Zeeweed® 500D membranes were aged at bench-scale by single soaking in hypochlorite solution at similar concentration and pH of MBR cleaning protocols. In addition, membranes were sampled between 2016 and 2021 from the full-scale MBRs of Seine Morée (capacity: 50 000 m3/d) and Seine aval (capacity: 300 000 m3/d) wastewater treatment plants in northern Paris in operation since 2014 and 2017, respectively. Simultaneously, process data were collected and analyzed. Both bench-scale and full-scale aged hollow-fibers were compared by the chlorine exposure dose (C x t) and characterized using similar analytical methods. Great differences were found between ageing at bench-scale and full-scale. At bench-scale, membranes presented stable mechanical properties, intrinsic permeability increased at first as a result of hydrophilic agent degradation and small pores were formed (diameter < 20 nm), then it decreased as a result of a decrease in porosity, likely due to a restructuration of PVDF chains. At full-scale, permeability seemed to increase as a result of a more pronounced oxidation/dislodgement of PVP molecules leading to higher porosity and the appearance of bigger pores (diameter > 40 nm). These changes favored irreversible fouling in contrary to bench-scale ageing. Ageing was also described based on permeability index after each cleaning in place protocol. This is the ratio of permeate flux and transmembrane pressure when membranes are in operation at full-scale. The permeability index decreased over time and this decline rate seemed to vary according operating conditions. Due to these differences, cumulative indicators associated to the process conditions were developed to enable a more accurate monitoring of membrane ageing among MBRs. Correlations among these indicators, membrane properties and permeability index were performed. The cumulated filtered mixed liquor suspended solids (MLSS) mass was found to correlate well with most of the membrane properties and permeability index from both MBRs and should be included in membrane ageing studies. In addition, the decline in permeability index correlated well with PVP content and intrinsic permeability, thus these are key indicators for membrane ageing monitoring.

Key-words: membrane bioreactor, ultrafiltration, hollow-fiber, wastewater treatment, multi-scale, full-scale, long-term operation.

Date et heure

(Friday) 15 h 00 min - 18 h 00 min

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