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Biodegradation Kinetics (biodegradation + kinetics)
Selected AbstractsBiodegradation kinetics of benzene, methyl tert -butyl ether, and toluene as a substrate under various substrate concentrationsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2007Chi-Wen Lin Abstract Owing to the complexity of conventional methods and shortcomings in determining kinetic parameters, a convenient approach using the nonlinear regression analysis of Monod or Haldane type nonlinear equations is presented. This method has been proven to provide accurate estimates of kinetic parameters. The major work in this study consisted of the testing of aromatic compound-degrading cultures in batch experiments for the biodegradation of benzene, methyl tert -butyl ether (MTBE), and toluene. Additionally, batch growth data of three pure cultures (i.e., Pseudomonas aeruginosa YAMT421, Ralstonia sp. YABE411 and Pseudomonas sp. YATO411) isolated from an industrial petrochemical wastewater treatment plant under aerobic conditions were assessed with the nonlinear regression technique and with a trial-and-error procedure to determine the kinetic parameters. The growth rates of MTBE-, benzene-, and toluene-degrading cultures on MTBE, benzene, and toluene were significant. Monod's model was a good fit for MTBE, benzene and toluene at low substrate concentrations. In contrast, Haldane's equation fitted well in substrate inhibition concentration. Monod and Haldane's expressions were found to describe the results of these experiments well, with fitting values higher than 98%. The kinetic parameters, including a maximum specific growth rate (µm), a half-saturation constant (Ks), and an inhibition constant (Ki), were given. Copyright © 2007 Society of Chemical Industry [source] Characterization and modelling of denim-processing wastewaters for activated sludgeJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2001Derin Orhon Abstract The study involved characterization of denim-processing wastewaters, mainly to generate the necessary experimental data for the modelling and evaluation of the activated sludge process. The striking feature of the wastewater quality was the excessive suspended solids content requiring effective removal before biological treatment. COD fractionation was, however, typical for a textile effluent in general, with a biodegradable fraction of 90%, a readily biodegradable COD ratio of 20%, a predominantly soluble slowly biodegradable fraction of 55,60% and negligible particulate inert COD. Hydrolysis was identified as the significant step in the biodegradation kinetics with rate coefficients quite specific to plant operation. Evaluation of the hydrolysis kinetics showed that the magnitude of the slowly biodegradable COD could be reduced with a higher hydraulic detention time, effectively improving the quality of the soluble effluent. © 2001 Society of Chemical Industry [source] Modeling for batch phenol biodegradation with immobilized Alcaligenes faecalisAICHE JOURNAL, Issue 4 2006Xiaoqiang Jia Abstract Intrinsic cell growth and phenol biodegradation kinetics of Alcaligenes faecalis were studied in shaking flasks. Batch phenol biodegradation experiments were carried out in a 7.5 L fermentor with immobilized Alcaligenes faecalis in polyurethane foams. A double-layer reaction-diffusion model was developed to describe the dynamic behaviors of batch phenol biodegradation processes. Phenol degradation (within the cell-immobilized polyurethane foams as well as in the main liquid phase) and cell growth (within the cell-immobilized polyurethane foams only) at different initial phenol concentrations were simulated and analyzed in terms of both biodegradation time and layer radius course. The good agreement between the model simulations and the experimental measurements for phenol degradation in the main liquid phase validates the proposed double-layer reaction-diffusion model. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] Investigating the importance of flow when utilizing hyaluronan scaffolds for tissue engineeringJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 2 2010Gail C. Donegan Abstract Esterified hyaluronan scaffolds offer significant advantages for tissue engineering. They are recognized by cellular receptors, interact with many other extracellular matrix proteins and their metabolism is mediated by intrinsic cellular pathways. In this study differences in the viability and structural integrity of vascular tissue models cultured on hyaluronan scaffolds under laminar flow conditions highlighted potential differences in the biodegradation kinetics, processes and end-products, depending on the culture environment. Critical factors are likely to include seeding densities and the duration and magnitude of applied biomechanical stress. Proteomic evaluation of the timing and amount of remodelling protein expression, the resulting biomechanical changes arising from this response and metabolic cell viability assay, together with examination of tissue morphology, were conducted in vascular tissue models cultured on esterified hyaluronan felt and PTFE mesh scaffolds. The vascular tissue models were derived using complete cell sheets derived from harvested and expanded umbilical cord vein cells. This seeding method utilizes high-density cell populations from the outset, while the cells are already supported by their own abundant extracellular matrix. Type I and type IV collagen expression in parallel with MMP-1 and MMP-2 expression were monitored in the tissue models over a 10 day culture period under laminar flow regimes using protein immobilization technologies. Uniaxial tensile testing and scanning electron microscopy were used to compare the resulting effects of hydrodynamic stimulation upon structural integrity, while viability assays were conducted to evaluate the effects of shear on metabolic function. The proteomic results showed that the hyaluronan felt-supported tissues expressed higher levels of all remodelling proteins than those cultured on PTFE mesh. Overall, a 21% greater expression of type I collagen, 24% higher levels of type IV collagen, 24% higher levels of MMP-1 and 34% more MMP-2 were observed during hydrodynamic stress. This was coupled with a loss of structural integrity in these models after the introduction of laminar flow, as compared to the increases in all mechanical properties observed in the PTFE mesh-supported tissues. However, under flow conditions, the hyaluronan-supported tissues showed some recovery of the viability originally lost during static culture conditions, in contrast to PTFE mesh-based models, where initial gains were followed by a decline in metabolic viability after applied shear stress. Proteomic, cell viability and mechanical testing data emphasized the need for extended in vitro evaluations to enable better understanding of multi-stage remodelling and reparative processes in tissues cultured on biodegradable scaffolds. This study also highlighted the possibility that in high-density tissue culture with a biodegradable component, dynamic conditions may be more conducive to optimal tissue development than the static environment because they facilitate the efficient removal of high concentrations of degradation end-products accumulating in the pericellular space. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||