L’élimination des micropolluants organiques est devenue aujourd’hui un objectif de santé publique car leur toxicité et bioaccumulation au travers de la chaine trophique sont incontestables. Les hydrocarbures aromatiques polycycliques (HAP) et le nonylphénol (NP) présents en faible concentration dans l’eau usée sont peu éliminés par le traitement. Ces composés hydrophobes se retrouvent fortement sorbés à la matière organique des boues de station d’épuration. Les procédés de traitement de ces boues, comme la digestion anaérobie (DA) jouent un rôle central car ils constituent une des dernières barrières avant rejet vers l’environnement par épandage. La DA élimine les HAP et le NP mais les performances restent insatisfaisantes. L’objectif de cette thèse est d’améliorer les performances d’élimination des HAP et NP par la DA en utilisant l’électrolyse microbienne et l’ajout des matériaux conducteurs. Les résultats montrent que le graphite poreux permet de lever deux limites à la bioremédiation des HAP: le manque d'accepteurs d'électrons terminaux et la biodisponibilité limitée des HAP. En effet, le graphite poreux semble faciliter l'échange direct d'électrons avec la communauté syntrophique anaérobie ce qui améliore les performances d’hydrolyse de la matière et des contaminants associés, particulièrement, l’élimination de 12 HAP est accrue de 21 à 33 %. Pour le NP, les processus impliqués semblent être différents car aucune amélioration n’est observée quelles que soient les conditions.. L’addition du graphite non-poreux (avec une surface spécifique moindre) et du platine (avec une conductivité plus élevée) n’éliminait que deux HAP de faible poids moléculaire suggérant que la conductivité ne constitue pas un facteur majeur dans la dissipation des HAP. L’ajout du graphite poreux en plus grande quantité, par contre, n’a pas confirmé l’hypothèse qu’une augmentation de surface spécifique du matériau conducteur accroit également l’élimination des HAP. Lors de la DA assistée par différents matériaux, un enrichissement de méthanogènes hydrogénotrophs a été constaté qui pourra être à la racine des performances observées. Dans ce contexte, la composition microbienne de l’inoculum joue un rôle majeur dans l’ampleur d’une biodégradation des HAP. L'utilisation de matériaux conducteurs abordables tels que le graphite poreux et non-poreux pourrait présenter une stratégie de biodégradation alternative pour éliminer les HAP des boues, du sol ou des sédiments. / The elimination of organic micropollutants from the environment has become a public health goal today because of their toxicity and bioaccumulation through the trophic chain. Polycyclic aromatic hydrocarbons (PAHs) and nonylphenol (NP) are found at low concentrations in wastewaters. They are removed from wastewaters by sorption onto sewage sludge due to their hydrophobicity. Anaerobic digesiton (AD) that is used for sewage sludge treatmentThe treatments of these sludge, like anaerobic digestion (AD), therefore, plays a central role in reducing the micropollutant load before dissemination to the environment via sludge spreading. Removal performances of PAHs and NP are removed byunder AD are, yet, but limitedwith low performances. The aim of this PhD work is to enhance removalthese performances thanks to the use of two emerging techniques, microbial electrolysis and the addition of conductive materials. The results demonstrate that independent of the application of a potential porous graphite circumvents two limits of PAH bioremediation: the lack of terminal electron acceptors and PAHs’ limited bioavailability. Mediatorless electron exchange between the anaerobic syntrophic community and the conductive material presumably facilitates sludge hydrolysis which, in turn, leads to the enhanced bioavailability of PAHs and their subsequent biodegradation. The reductions of 12 PAHs were improved by 21 to 33% while NP was eliminated to the same extent in the digesters with and without conductive material. The addition of non-porous graphite (with less specific surface) and platinum (exhibiting higher conductivity) eliminated only two low molecular weight PAHs suggesting that conductivity is not a major factor in the dissipation of PAHs. The addition of porous graphite in larger quantities, however, did not support the hypothesis that an increase in specific surface area of the conductive material also enhances the removal of PAHs. During conductive material supplemented AD, an enrichment of hydrogenotrophic methanogens was ascertained which could be at the root of the removal performance. In this context, the microbial composition of the inoculum plays a major role in the extent of PAH biodegradation. The use of affordable conductive materials such as porous and non-porous graphite may present an alternative biodegradation strategy for removing PAHs from sludge, soil or sediments.

This thesis investigates an alternative solution to deal with the civil structure vibration. Non-contact electromagnetic or Eddy current damping is selected as a score of vibration suppression. Electromagnetic damping relies on the interaction between a permanent magnet and conductor. An electromagnetic damper (EMD) is applied both to a laboratory footbridge structure and 6-storey model-scale aluminium moment resisting frame (AMRF). In this first study the EMD is connected in series with an electronic shunt circuit to construct an electromagnetic shunt damper (EMSD). A robust optimisation method is applied to develop the corresponding optimal design formula of the EMSD. The principle of an EMSD is to convert mechanical energy to electrical energy. Hence, the induced electromotive force (emf) is generated by electromagnetic induction. This emf induces an amount of shunt damping, which is fedback to the structure to achieve vibration suppression. It was found that when the impedance was applied, the shunt damping feature was of a similar nature to viscous dampers. In contrast, when an RLC (resistance-inductance-capacitance) circuit is connected, the shunt damping is analogous to a tuned mass damper. A second form of EMD is Eddy current damper (ECD), which relies on a geometrical arrangement of permanent magnets and conductors to produce damping forces. The vertical and horizontal orientation of the magnet, unidirectional and alternative pole projection and moving different direction of the conductor are investigated. A theoretical study involving the infinite boundary and finite boundary (the method of images current) is carried out to obtain an analytical calculation of the damping force. On the basis of this analysis, one type of ECD prototype was physically built. A performance test was carried out to determine the damping characteristics of the ECD, which agreed with the results of the numerical analysis. In addition, the ECD was applied to control the dynamics of the 6-storey AMRF. It was found that, the ECD can effectively increase system damping and have a satisfactory control effect.