Modeling and Optimization of Gas Sparging-Assisted Bacterial Cultivation Broth Microfiltration by Response Surface Methodology and Genetic Algorithm.

Aleksandar Jokić,Arpad Kiralj,Vanja Vlajkov,Selena Dmitrović,Jovana Grahovac,Nataša Lukić,Ivana Pajčin

doi:10.3390/membranes11090681

Abstract

Production of highly efficient biomass-based microbial biopesticides significantly depends on downstream processing in terms of obtaining as high concentration of viable cells as possible. Microfiltration is one of the recommended operations for microbial biomass separation, but its main limitation is permeate flux decrease due to the membrane fouling. The effect of air sparging as a hydrodynamic technique for improvement of permeate flux during microfiltration of Bacillus velezensis cultivation broth was investigated. Modeling of the microfiltration was performed using the response surface methodology, while desirability function approach and genetic algorithm were applied for optimization, i.e., maximization of permeate flux and minimization of specific energy consumption. The results have revealed antagonistic relationship between the investigated dependent variables. The optimized values of superficial feed velocity and transmembrane pressure were close to the mean values of the investigated value ranges (0.68 bar and 0.96 m/s, respectively), while the optimized value of superficial air velocity had a more narrow distribution around 0.25 m/s. The results of this study have revealed a significant improvement of microfiltration performance by applying air sparging, thus this flux improvement method should be further investigated in downstream processing of different bacterial cultivation broths.

Highlights

Nowadays, conventional agriculture often depends on chemical pesticides and inorganic fertilizers in order to achieve stable and great quantity agricultural output
The results of this study have revealed a significant improvement of microfiltration performance by applying air sparging, this flux improvement method should be further investigated in downstream processing of different bacterial cultivation broths
Microfiltration experiments were performed according to the Box–Behnken’s experimental plan (Table 1), where the effects of microfiltration operational conditions to steady state permeate flux (J) and specific energy consumption (E) were investigated

Summary

Introduction

Conventional agriculture often depends on chemical pesticides and inorganic fertilizers in order to achieve stable and great quantity agricultural output. I.e., cultivation broth clarification, is the step in downstream processing with an aim of a solid/liquid separation to recover the microbial cells from their suspending medium in order to increase concentration of the active component in the final biopesticide product. The effective recovery of the cultivation broth components, especially microbial biomass considering necessity to maintain cell viability, is the penultimate step in biopesticide production, which can directly affect product formulation and product efficiency. When it comes to Bacillus-based biopesticides production, this downstream separation step has not been addressed comprehensively yet

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