Estudio de la aplicabilidad de un polímero de ciclodextrina como soporte para la eliminación de fenol en un reactor biológico de lecho fluidizado

Resumen

ESTUDIO DE LA APLICABILIDAD DE UN POLÍMERO DE CICLODEXTRINA COMO SOPORTE PARA LA ELIMINACIÓN DE FENOL EN UN REACTOR BIOLÓGICO DE LECHO FLUIDIZADO RESUMEN: "Contamination of waters is a high-priority subject in the European environmental "icy. Phenol, among organic pollutants, is spilled by many industries and its concentration is "limited due to its high toxicity to people and aquatic organisms. Biological treatment can be an attractive technique to eliminate phenol because of its low costs and minimal generation of dangerous by products. In fluidized bed biological reactors, microorganisms grow on a particle support suspended by the up-flow of polluted water. The advantages of this configuration lie on the limited space requirements, although high power is needed to fluidize the support. Therefore, using low density supports could be an interesting alternative to conventional supports (sand, activated charcoal, etc.). cyclodextrins are cyclic oligosaccharides constituted by several glucose units, with a hidrophobic cavity and a hidrophilic edge. This structure enables cyclodextrins to form inclusión complexes with hidrophobic substances, maintaining its solubility. Ocasionally, crosslinking of cyclodextrin is suitable in order to control its solubility without loosing its inclusión ability. Cyclodextrin polymers crosslinked with epyclorhidrin have been frequently used for the adsorption of aromatic compounds, showing an activity of both the polymeric network and cyclodextrins. These polymers have hydrogel Kroperties, so they can swell a lot. Consequently, their densities are slightly igher than water. In this work, the application of an insoluble polymer of b-cyclodextrin (PbCD) as support for a fluidized bed biological reactor (fbbr) has been studied in order to elimínate phenol from polluted waters. Firstly, a hydrodynamical characterization of the polymer was made with the purpose of studying its behaviour when the support is fluidized by water. Then, it was compared with other typical supports described by general equations. Afterwards, when the biofilm of microrganisms adapted to the biodegradation of phenol was grown around the polymer, the operation of the fluidized bed biological reactor was evaluated for different conditions of operation, studying the influence of different operation parameters in its biodegradative activity. The performance of the fbbr was compared with a completely stirred tank reactor (CSTR), which also used PbCD as support and phenol as polluting agent, and whose efficiency was evaluated for several conditions. Biodegradative activity of fbbr was characterized by a simple mathematical model based on two typical kinetics of biological growth (Monod and Andrews). Finally, the performance of fbbr was studied when the system was under several disturbances. The aim of these experiments was to evaluate the increase in toughness of fbbr when PbCD is used as support. In order to evaluate that toughness, periods of starvation of variable duration were applied to FBBR, as well as shock loads of variable magnitude and duration. In addition, the influence of additional nutrients and oxygen absence was studied.