Modeling of a vapor-phase fungi bioreactor for the abatement of hexane: Fluid dynamics and kinetic aspects

During some previous works, a packed-bed lab-scale biofilter (177 · 10-6 m3), inoculated with a selected strain of Aspergillus niger had been tested for the abatement of hexane vapors, showing a maximum elimination capacity of 200 g hexane/m3 reactor/h. A steady-state mathematical model taking into account axial dispersion effect was applied to describe the process and predict experimental results, but many model parameters could not be calculated from experimental data. The aim of the present work was to carry out further investigations to accurately determine the dispersion coefficient and the kinetics parameters to verify the effective validity of the model. Analysis of residential time distribution revealed the presence of a certain degree of axial dispersion (dispersion coefficient D of 1.22 · 10-4 m2/s). Experimental data from kinetic trials carried out in reduced height reactors, together with data from full-scale runs, were elaborated to estimate the kinetic saturation constant (Ks), the coefficient yield (Y), the maximum growth rate (μmax) and maximum substrate degradation rate (rmax). All these parameters were introduced into the model, which was then solved by simulation software finding a good correlation between experimental and theoretical results. © 2004 Wiley Periodicals, Inc

Xylitol crystallization from synthetic solutions: The combined effects of xylitol supersaturation level and cooling temperature

The aim of the present work was to evaluate a xylitol down-stream methodology combining low pressure evaporation and cooling

Glucose syrup and corn steep liquor as alternative to molasses substrates for production of baking-quality yeast

In the present study the possibility of substituting molasses with glucose syrup produced from corn starch and supplemented with corn steep liquor (CSL) (a by-product of cornstarch extraction process) as a source of proteins, vitamins and oligo-elements was investigated. For this purpose, fed-batch fermentations with constant volume were carried out to evaluate the influence of molasses sugars replacement (0-30-60-100%) by glucose syrup on biomass growth, yield coefficient (Yx/s) for substrate conversion into biomass, nitrogen and phosphorus (as P2O5) content of final biomass. A mixture of cane and beet molasses was used, and integrations of nitrogen, phosphorus, biotin, thiamin, inositol, nicotin amide, nicotinic acid, piridoxin and zinc were supplied For fermentations with 100% of sugars as glucose, addition of corn steep was considered and calculated on the basis of CSL and molasses composition. A substitution of molasses sugars up to 60% led only to a slight reduction in biomass nitrogen content. Complete replacement of molasses sugars brought to reduced biomass yield (partly due to the absent buffering power of molasses and then to an excessive pH reduction of medium during fermentation), Yx/s, nitrogen content, and higher phosphorus content. In this case, addition of CSL could partly compensate the negative effects. Copyright © 2009, AIDIC Servizi S.r.l