Sergio Alejandro Medina-Moreno

The biodecoloration of an industrial textile effluent with indigo blue dye in an up-flow packed-bed bioreactor with Heterobasidion annosum immobilized under conditions approaching plug-flow was evaluated and modeling. The bioreactor operated with defined geometric parameters (L/dt > 5, L/dp > 50, ε » 1) as criteria that, together with the packed-bed Reynolds number (Rep < 10), approach the hydrodynamics of plug flow. Biodecoloration efficiencies ranged from 54.6% to 93.9% across several flow rates. A steady-state mathematical model incorporating a mass balance for an up-flow packed-bed bioreactor and Monod-like kinetics was developed and experimentally validated (= 0.9902, RMSD=0.1171). The model yielded a maximum specific dye removal rate linked to biomass enzymatic capability (qmax) of 0.0077 mg mg⁻¹ h⁻¹. Simulations demonstrated that increasing the concentration of immobilized biomass within the bed significantly reduced the residence time required for steady-state dye removal. The Damköhler number (DaI) was used to identify the biodecoloration rate-limiting step, which was limited by convective transport at low flow rates (Rep < 1.5) and by reaction kinetics at higher flow rates (Rep > 1.5). This study presents an engineering framework that combines hydrodynamic criteria with kinetic modeling, offering a predictive, scalable strategy for treating recalcitrant textile effluents in fungal-packed-bed bioreactors.

The present study evaluated the performance of the fungus Trichoderma reesei to tolerate and biodegrade the herbicide diuron in its agrochemical presentation in agar plates, liquid culture, and solid-state fermentation. The tolerance of T. reesei to diuron was characterized through a non-competitive inhibition model of the fungal radial growth on the PDA agar plate and growth in liquid culture with glucose and ammonium nitrate, showing a higher tolerance to diuron on the PDA agar plate (inhibition constant 98.63 mg L-1) than in liquid culture (inhibition constant 39.4 mg L-1). Diuron biodegradation by T. reesei was characterized through model inhibition by the substrate on agar plate and liquid culture. In liquid culture, the fungus biotransformed diuron into 3,4-dichloroaniline using the amide group from the diuron structure as a carbon and nitrogen source, yielding 0.154 mg of biomass per mg of diuron. A mixture of barley straw and agrolite was used as the support and substrate for solid-state fermentation. The diuron removal percentage in solid-state fermentation was fitted by non-multiple linear regression to a parabolic surface response model and reached the higher removal (97.26%) with a specific aeration rate of 1.0 vkgm and inoculum of 2.6 x 108 spores g-1. The diuron removal in solid-state fermentation by sorption on barley straw and agrolite was discarded compared to the removal magnitude of the biosorption and biodegradation mechanisms of Trichoderma reesei. The findings in this work about the tolerance and capability of Trichoderma reesei to remove diuron in liquid and solid culture media demonstrate the potential of the fungus to be implemented in bioremediation technologies of herbicide-polluted sites.

The present work evaluated the performance of the fungus Trichoderma reesei to tolerate and biodegrade the herbicide diuron in its agrochemical presentation in agar plate, liquid culture, and solid-state fermentation. The tolerance to diuron was characterized through a non-competitive inhibition model, showing higher tolerance on the PDA agar plate (K_i=98.63 mg L^− 1) than liquid culture with glucose and ammonium nitrate as carbon and nitrogen sources (K_i=39.4 mg L^− 1). Diuron biodegradation was characterized through the model of inhibition by the substrate. Trichoderma reesei had a maximum radial growth rate (v_rmax) of 1.17 cm d^− 1 on agar plate. In liquid culture, Trichoderma reesei biotransformed diuron in 3,4-dichloroaniline using the amide group from the diuron structure as a carbon and nitrogen source, with a maximum specific growth rate (µ_max) of 0.0245 h^− 1 and a yield of the biomass on the substrate (Y_XD) of 0.154 mg mg^− 1. In solid-state fermentation with a mix of barley straw and agrolite (70:30) as support-substrate, the maximum diuron removal percentage (97.26%) was reached with a specific aeration rate of 1.0 vkgm, inoculum of 2.6x10⁸ spores g^− 1, and an initial diuron concentration of 160.81 mg kg^− 1. The diuron removal in solid-state fermentation by sorption on the barley straw and agrolite was discarded compared with the removal magnitude of the biosorption and biodegradation mechanisms of Trichoderma reesei. The Trichoderma reesei performance in its tolerance and capability to remove diuron in liquid and solid culture media displays its potential to be used in bioremediation technologies of herbicides polluted sites.

Bioscorodite crystallization is a promising process for the proper immobilization of arsenic from acidic metallurgical wastewater, and Acidianus brierleyi is an effective archaeon to oxidize Fe(II) and As(III) simultaneously. This paper deals with the development of an experimentally validated mathematical model to gain insight into the simultaneous processes of Fe(II) and As(III) oxidation via microbial cells and the exopolysaccharide (EPS) matrix, As(V) precipitation, and bioscorodite crystallization, which are affected by several factors. After the mathematical structure was proposed, a model fitting was performed, finding global determination coefficients between 0.96 and 0.99 (with p-values < 0.001) for all the variables. The global sensitivity analysis via Monte Carlo simulations allowed us to identify the critical parameters whose sensitivity depends on culture conditions. The model was then implemented to evaluate the effect of cell concentration, Fe(II) and As(III) concentrations (at Fe/As = 1.4), and oxidation rate constants for A. brierleyi and the EPS region, noting that these factors play an important role in the process. Our results showed that the proposed model can be used as a robust simulation platform for the further analysis of the bioscorodite crystallization process under extremophilic conditions.

In some fermentation systems, whey components (lactose, proteins and minerals) can produce isopentyl acetate (IA). An analysis of the best conditions for IA production with Kluyveromyces marxianus was developed in this work. The experiment design was two-factor and three-level design based on a response surface methodology (RSM) using Design-Expert^® software. The analysis of anomeric protons by nuclear magnetic resonance (1H-NMR) showed 81.25% of β lactose content. This characteristic favored the production of IA. The maximum output (Mp) of IA, determined by gas chromatography, was 9.52 g/L (p < 0.05). The central composite design (CCD) was used to perform the factor analysis. Results showed that concentrations of 0.03 (g/L) ammonium sulphate and 0.3 (v/v) of isoamyl alcohol are the best conditions for a maximum rate of IA production. The production of IA can reduce the discharge of whey, allowing its reuse and revaluation.