Wastewater treatment by novel hybrid biological – ion exchange processes

This study presents two novel methods for treating important environmental contaminants from two different wastewater streams. One process utilizes the kinetic advantages and reliability of ion exchanging clinoptilolite in combination with biological treatment to remove ammonium from municipal sewage. A second process, HAMBgR (Hybrid Adsorption Membrane Biological Reactor), combines both ion exchange resin and bacteria into a single reactor to treat perchlorate contaminated waters. Combining physicochemical adsorptive treatment with biological treatment can provide synergistic benefits to the overall removal processes. Ion exchange removal solves some of the common operational reliability limitations of biological treatment, like slow response to environmental changes and leaching. Biological activity can in turn help reduce the economic and environmental challenges of ion exchange processes, like regenerant cost and brine disposal. The second section of this study presents continuous flow column experiments, used to demonstrate the ability of clinoptilolite to remove wastewater ammonium, as well as the effectiveness of salt regeneration using highly concentrated sea salt solutions. The working capacity of clinoptilolite more than doubled over the first few loading cycles, while regeneration recovered more than 98% of ammonium. Using the regenerant brine for subsequent halotolerant algae growth allowed for its repeated use, which could lead to cost savings and production of valuable algal biomass. The algae were able to uptake all ammonium in solution, and the brine was able to be used again with no loss in regeneration efficiency. This process has significant advantages over conventional biological nitrification; shorter retention times, wider range of operational conditions, and higher quality effluent free of nitrate. Also, since the clinoptilolite is continually regenerated and the regenerant is rejuvenated by algae, overall input costs are expected to be low. The third section of this study introduces the HAMBgR process for the elimination of perchlorate and presents batch isotherm experiments and pilot reactor tests. Results showed that a variety of ion-exchange resins can be effectively and repeatedly regenerated biologically, and maintain an acceptable working capacity. The presence of an adsorbent in the HAMBgR process improved bioreactor performance during operational fluctuations by providing a physicochemical backup to the biological process. Pilot reactor tests showed that the HAMBgR process reduced effluent perchlorate spikes by up to 97% in comparison to a conventional membrane bio-reactor (MBR) that was subject to sudden changes in influent conditions. Also, the HAMBgR process stimulated biological activity and lead to higher biomass concentrations during increased contaminant loading conditions. Conventional MBR systems can be converted into HAMBgR’s at a low cost, easily justifiable by the realized benefits. The concepts employed in the HAMBgR process can be adapted to treat other target contaminants, not just perchlorate.

Les étrangers aux frontières de la France : étude de récits de migration (1870 à nos jours)

In this dissertation, I examine how migration narratives make an ambiguous contribution to the democratization of French national borders. National borders are essentially spaces of crises from which it is possible to study the constant evolution of national identity. Migration narratives, regardless of their ideological dimension, offer representations of the border and of the foreigner that result from a tension between the difficulty to think identity outside of the national frame and the questioning of such a strong tie between identity and the nation. At the border, identities are fundamentally unstable. The first part is focused on the north-eastern and the southern borders of France at the end of the 19th century. The French nationalist literature at the time, advocating for the return of Alsace-Lorraine to the Republic, is characterized by a tension between nationalism and regionalism. The ideology of latinity constitutes a second major feature of the discourse on French identity. Developed by Louis Bertrand, it claims that France can only be regenerated in Algeria. However, a gap between his fictional works and his essays reveals latinity as hybrid and heterogeneous. Borders are also polysemic, namely, they do have the same meaning for everyone. The second part of the dissertation focuses on the southern border of France from the 30s to the 90s. The study of films and novels demonstrate that former borders are still active, especially colonial borders. Finally, the third part of the dissertation addresses the representation of migrants who were trapped in the north of France, at the border of the Schengen area, from the 90s to 2009. Migration narratives bring attention to the totalitarian tendencies of the state, but they also struggle with the contradictions of the humanitarian discourse and the analogies made with previous immigration waves.