Evaluation of effective diffusion coefficient and intrinsic kinetic parameters on azo dye biodegradation using PVA‐immobilized cell beads

Abstract

An immobilized mixed culture (Aeromonas hydrophila, Comamonas testosteroni, and Acinetobacter baumannii) was prepared by entrapment into phosphorylated polyvinyl alcohol (PVA) gel beads. The unsteady-state diffusion mechanism in a gel bead was applied to estimate the effective diffusion coefficients (D(e)) and the partition coefficients (K(p)) of azo dye. In addition, a simple method was developed to determine the intrinsic kinetic parameters of immobilized cells from observed reaction rates and the intrinsic kinetic parameters were then verified by fitting the experimental data into the reaction-diffusion model in a batch reactor running at a well-stirred state. The calculated effectiveness factor (eta(cal)) approached unity at Thiele modulus (Phi) < 0.3 (i.e., d(p) < 0.475 mm). The experimental effectiveness factor (eta(exp)) was in the range of 0.71-0.45 for a corresponding sphere diameter (d(p)) of 1.91 +/- 0.16 to 4.43 +/- 0.07 mm at an initial dye concentration of 200 mg/L. The results show that intraparticle diffusion resistance has a significant effect on the azo dye biodegradation rate.

Hydrodynamic characteristics of immobilized cell beads in a liquid–solid fluidized‐bed bioreactor

“…The biomass of the immobilized cell beads increased, reaching a stable level after 7 days of cultivation. The physical properties of the gel beads with/without cells were obtained according to our previously studies (Chen and Lin, 1994;Chen et al, 2003b), the biomass concentration in the gel beads was determined ac-cording to the bicinchoninic acid assay method modified according to our previous study (Chen et al, 1998). Figure 1 illustrates the LSFBR system used for the experiments.…”

“…Immobilized cell methods can be divided mainly into two groups: the binding method (Blanco et al, 1995;Mulcahy and Shieh, 1987) and the entrapping method (Hashimoto and Furukawa, 1987;Chen and Lin, 1994;Kudlich et al, 1996). In our previous study, a mixed culture having a high capacity for rapid decolorization of azo dye was immobilized by a phosphorylated polyvinyl alcohol (PVA) gel (Chen et al, 2003b). The PVA immobilized cell beads exhibited a remarkable color removal capability in batch experiments.…”

“…Therefore, a detailed knowledge of hydrodynamic behavior of carrier particles is the first essential step for the correct design and operation of the FBRs. Nevertheless, very little information is available in the literature regarding the hydrodynamic behaviors of gel beads in the FBRs, although we have provided extensive information on the mechanical strength, gel structures, and internal diffusional limitations of PVA immobilized cell beads in our previous research (Chen et al, 2003b).…”

Removal of acid red 88 from wastewater by adsorption on agrobased waste material. A case study of Iranian golden Sesamum indicum hull

“…Because of composing chelate by metal ions produce micro-toxicity to fish and other organisms (1,2). The release of azo dyes into the environment is a concern due to coloration of natural waters, toxicity, mutagenicity and carcinogenicity of these dyes and their bio-transformation products (3,4). Some dyes under anaerobic conditions in wastewater, may decompose into carcinogenic aromatic amines and cause serious malady to men and animals (5,6).…”

Mass Transfer in Bioreactors

“…The diffusion coefficient in the AC core was calculated by the method explained in Hines and Hines and Maddox (1987), supposing Knudsen diffusivity, but the value was changed in two orders of magnitud in order to fit the model ; Lee et al2006), comparing the values reported for other dyes in references. The diffusivity in the biofilm was assumed to be 100 times larger than the diffusivity in the AC core, based in values reported for other dyes of the same kind (Fan et al 1987;Chen et al 2003). The kinetic constants were estimated from experimental data and fitted to model.…”