This work is focused on the evaluation of a beta-cyclodextrin polymer as a carrier medium in a fluidized bed bioreactor treating aqueous phenol as a model pollutant. The insoluble polymer support was obtained in the shape of spherical beads by crosslinking beta-cyclodextrin with epichlorohydrin. A batch of swollen polymer particles was loaded into the reactor and inoculated with a mixed bacterial culture. Bacterial growth on the polymer beads was initially stimulated by glucose addition to the medium, and then gradually replaced with phenol. The operational variables studied after the acclimation period included phenol load, hydraulic residence time and recirculation flow rate. Low hydraulic residence times and moderate phenol loads were applied. The elimination capacity was usually about 1.0 kg-phenol/m(3)d, although a maximum of 2.8 kg-phenol/m(3)d was achieved with a retention time of only 0.55 h. The depuration efficiency was not affected by the recirculation flow rate in the range studied. Neither operational nor support stability problems were detected during the operation. A high degree of expansion was achieved in the bioreactor due to the hydrogel nature of the cyclodextrin polymer and, consequently, a low energy requirement was necessary to fluidize the bed.

ABSTRACT:The suspension polymerization of ␤-cyclodextrin (␤-CD) with epichlorohydrin (EP) has been studied using a fractionated factorial design with two levels and six variables (␤-CD:EP molar ratio, NaOH concentration, temperature, stirring speed, delay time before paraffin addition, and ␤-CD concentration). Different variables, such as the amount of ␤-CD in the product, particle size, degree of swelling, and sorption capacity, have been analyzed as the responses for the synthesized polymers. The experimental design approach permitted to select the optimal conditions of synthesis depending on the desired features of the product.

BACKGROUND: Because of the lower fluidization energy required and the protection against shock loading and starvation due to their sorption capacity, light adsorbents such as hydrogels could be used as biofilm carrier media in fluidized bed bioreactors for wastewater processing. This work explores the feasibility of a cyclodextrin hydrogel as biomass support to degrade phenol under extremely low-nitrogen availability and under nitrogen amendments.

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