Effects of the liquid vapor oxygen transfer coefficient (k_Lα) on ethanol production from cassava residue and analysis of the fermentation kinetics

Abstract

Cassava residue is the solid waste generated from the production of tapioca starch and has considerable reuse value. In this study, cassava residue was examined as a hydrolysate for ethanol production, and the effects of different liquid phase oxygen transfer coefficients (k L α) on the production of ethanol from cassava residue hydrolysates were studied. Based on analyses of dissolved oxygen and a set of optimal experimental schemes, dynamic models of cell growth and product synthesis were optimized, using MATLAB. When k L α was 85, fermentation was optimal; the ethanol titer reached 23.14 g L −1 at 72 h and cell growth reached 6.23 g L −1 at 96 h. Additionally, experiments were performed according to the dissolved oxygen curve obtained under these conditions. The resulting ethanol titer was 24.43 g L −1 (72 h) and the cell mass was 6.45 g L −1 (96 h). 84

Co‐fermentation metabolism characteristics of apple vinegar with Acetobacter pasteurianus and Lactobacillus plantarum

“…The total acid was titrated using an acid-base method. The ethanol content was determined using a 7890A gas chromatography (GC) detection system (Agilent, State of California, USA) equipped with an Aminex DB-624 25 m × 0.200 mm column (Agilent, USA), in accordance with previous methods (Li et al, 2018). The reducing sugar content was measured using a DNS kit (Solarbio, Beijing, China).…”

Gas pressure intensifying oxygen transfer to significantly improving the bio‐oxidation productivity of whole‐cell catalysis

“…22,23 OTR (K L α), an important index for simulating aerobic cell reaction process and reactor design and amplification. 24,25 Therefore, optimizing the two factors, C* À C L and K L α, could be the main strategy to improve OTR. On the other hand, to improve the driving force of mass transfer C* parameter should be increased, mainly by reducing biocatalysis temperature, changing broth solute, and increasing oxygen partial pressure.…”

“…K L represents the oxygen mass transfer coefficient driven by concentration difference (m/h); α represents the specific surface area (m 2 /m 3 ); C * represents the saturated DO concentration (mmol/L); C L represents the DO concentration in the broth (mmol/L); C * − C L means the difference of oxygen concentration, which is the driving force affecting the transfer rate. Moreover, in industry, K L and α are combined into one parameter, designed as volume transfer coefficient ( K L α ), an important index for simulating aerobic cell reaction process and reactor design and amplification 24,25 . Therefore, optimizing the two factors, C * − C L and K L α , could be the main strategy to improve OTR.…”

Development of modeling and simulation of bubble‐liquid hydrodynamics in bubble column

“…Early studies have usually focused on the laminar flow mode system, and the bubble behaviors were not be considered. [10][11][12][13][14][15] Hu et al 16 found that threshold values for mammalian cells growing in suspension cover a wide range of from 8 to 450 Pa and cannot obtain a precise value. Nienow et al 17 indicted that if hydrodynamic stress is lower than critical value, it makes no effect on cell growth; however, the negative response will result in the slower growth, change of metabolism, etc, when it exceeds over threshold value.…”

“…[10][11][12][13][14][15] Hu et al 16 found that threshold values for mammalian cells growing in suspension cover a wide range of from 8 to 450 Pa and cannot obtain a precise value. [10][11][12][13][14][15] Hu et al 16 found that threshold values for mammalian cells growing in suspension cover a wide range of from 8 to 450 Pa and cannot obtain a precise value.…”