Continuous Production Of Acetic Acid Research Articles

Production of Acetic Acid and Whey Protein from Cheese Whey in a Hybrid Reactor under Response Surface Optimized Conditions

Experimental investigations were carried out in a membrane-integrated hybrid bio-reactor system for direct and continuous production of acetic acid and whey protein from waste cheese whey under response surface optimized conditions. In this novel scheme of fermentative production, using Acetobactor aceti, the major operating parameters such as temperature, concentrations of yeast extract, and glucose were optimized. Under the set of optimum operating conditions (temperature of 300 °C, pH of 6.0, yeast extract concentration of 15 g/L and glucose concentration of 44 g/ L), more than 95% pure acetic acid was produced with a concentration of 84.1 g/L, yield of 97.4% and productivity of 7.2 g/(L· h). Simultaneous production of whey protein powder makes the process more economically viable. Findings indicate that acetic acid could be produced directly and continuously from waste cheese whey with high productivity, yield and purity under response surface optimized conditions, in a simple, flexible, energy-saving and environmentally benign membrane-integrated hybrid reactor system.

Modeling and simulation of direct production of acetic acid from cheese whey in a multi-stage membrane-integrated bioreactor

Modeling and simulation of direct and continuous production of acetic acid in a two-stage membrane-integrated hybrid reactor system was done. The total production and purification scheme involved fermentation of a cheap, renewable carbon source (cheese whey) under non-neutralizing regime in a membrane-integrated new reactor with provisions of downstream separation and recycle of microbial cells and unconverted carbon source from product acetic acid by microfiltration and nano-filtration membranes. The model attempts to capture the major governing parameters like dilution rate, cross flow rate, recycling of materials, pH along with fermentation kinetics under substrate-product inhibitions and all the associated transport phenomena of the components through micro and nanofiltration membranes. The system produced 98.6% pure acetic acid at a flux of 75L/(m2h) with yield of 0.98g/g and productivity of 4.1g/(Lh). Performance of the model is well reflected in low relative error (<0.05), high Willmott d-index (d>0.97) and high overall correlation coefficient (R2>0.98).

Analysis of acetic acid productivity in a continuous two‐stage bioreactor with cell recycling

AbstractThe performance of a two‐stage system with cell recycling and fresh feed at each stage is studied numerically for continuous acetic acid production. In this system, both filtrate and bleed broth from the first stage are supplied to the second fermenter. At high substrate conversions, this configuration is found to provide higher acetic acid productivities than either a previous configuration where only the first‐stage bleed broth is fed to the second stage or a single recycle chemostat at the same bleed ratios. Copyright © 2005 Society of Chemical Industry

A shaking bioreactor equipped with twin ceramic membranes for acetic acid production using Acetobacter pasteurianus

A shaking bioreactor system with twin internal ceramic membranes was developed for effective perfusion culture and applied to the continuous production of acetic acid using Acetobacter pasteurianus. The system makes it possible to carry out the back-washing of the membrane without stopping the continuous operation because one membrane can be washed by medium feed flow while another membrane provides filtration of the broth by the simple switching of the medium and the broth flow direction. The medium flow through the membrane could successfully wash the surface of the membrane thereby effectively maintaining the filtration ability. By using the system, continuous operation of more than 800 h was achieved and the maximum acetic acid productivity reached 13.4 g l−1 h−1 using air enriched with 40% O2.

Continuous acetic acid production by a packed bed bioreactor employing charcoal pellets derived from waste mushroom medium

A packed bed bioreactor using charcoal pellets produced from waste mushroom medium by thermal carbonization was developed and applied to continuous acetic acid production. The pellets were characterized by their high specific surface area (200 m 2/g) with numerous micropores (2–10 μm). The continuous acetic acid fermentation started up smoothly after seeding and was successfully operated for about 180 d under various retention times. The maximum acetic acid productivity was about 3.9 g/ l/h using normal aeration and 6.5 g/ l/h using air enriched with 40% O 2. The pellets are expected to prove useful as a new packing material for bioreactor in terms of their bacterial affinity, high specific surface area with appropriate pore sizes for bacteria, as well as the operational stability of the system and the low production cost.

Analysis of a two-stage fermentor with cell recycling for continuous acetic acid production

The steady-state performance of a recycle two-stage fermentor with cell separators after each stage is studied numerically for continuous production of acetic acid. This system has two fresh-medium feed streams and the bleed withdrawn from the first stage is supplied to the second fermentor for utilization of the high cell concentration in the bleed. Kinetic expressions and parameter values are taken from the literature. The effects of operating parameters on the concentrations of cells, substrate and product in the two stages, the critical dilution rate for washout, the acetic acid productivity and the substrate conversion are examined and discussed. For overall productivity and conversion, the present two-stage system is found to be more efficient than a recycle chemostat and a recycle two-stage fermentor with a separator after the final stage. It exhibits sufficient promise for the continuous production of acetic acid that it should be tried out experimentally.

Performance of a multistage fermentor with cell filtering and recycling for continuous acetic acid production.

The steady-state performance of a multistage fermentor with cell filtering through a membrane and recycling of concentrated cells is studied numerically for continuous production of acetic acid. The tanks-in-series model is used to describe the flow behaviour of culture broth in the multistage fermentor. Kinetic expressions and parameter values are taken from the literature. The effects of the total number of stages, the dilution rate, the bleed ratio, the recycle ratio and the feed concentrations as operating conditions on fermentor characteristics such as the concentrations of total and viable cells as well as substrate and product in each stage, the cell viability, the acetic acid productivity and the substrate conversion were examined under the conditions of equal tank volumes and a recycle ratio equal to or greater than one. An increase in the number of stages and decreases in the bleed and recycle ratios and in the feed concentration of product enhance the productivity. The relations between the maximum productivity and the corresponding optimum dilution rate and between the corresponding outlet concentrations of the four components and the optimum dilution rate are presented as figures. Equations for the average cell viability and the critical dilution rate causing cell washout are also obtained. Furthermore, the minimum feed concentration of substrate for its complete consumption is mentioned. Compared to a single tank fermentor, staging and cell recycle increase substrate utilisation and acetic acid productivity. The computed performance of the fermentor configuration proposed in this study is sufficiently promising for the continuous production of acetic acid that it should now be checked experimentally.

Continuous Production of Acetic Acid from CO2 in Repeated-batch Cultures Using Flocculated Cells of Acetobacterum Woodii.

The biological utilization of CO2 in the production of acetic acid in anaerobic fermentations of Acetobacterium woodii was studied in a bubble-column bioreactor. To increase the productivity of acetic acid a repeated-batch culture technique was developed by introducing concentrated cells using a synthetic polymeric flocculant. The effects of the operating conditions of gas flow rate, cell density and medium composition on volumetric productivity of acetic acid were examined. At suboptimal operating conditions the production rates of various cultivation schemes were examined. This approach is especially valuable for simplification of the process and utilization of the energy required for the separation of the cells from the liquid content.

Multi-stage biofilm reactor for acetic acid production at high concentration

Continuous production of acetic acid by liquid surface culture ofAcetobacter aceti M7 was investigated using a Multi-Stage Biofilm Reactor (MSBFR) composed of ten shallow flow horizontal reactors of laboratory scale. With varying dilution rate in the range from 0.049 to 0.2 h−1, the maximum exit acetic acid concentration reached was as high as 98.0 g/l at the lowest dilution rate with step feed of ethanol-rich medium to stages 3, 5, and 7. The production rate (4.3 g/l/h) was rather high considering the inhibitory effect of high acetic acid concentration. This may be ascribed to non-homogeneous distribution of acetic acid concentration in the bioreactor and step feed of ethanol-rich medium.

Continuous acetic acid production by the bioreactor system loading a new ceramic carrier for microbial attachment

We have developed a bioreactor system for aerobic fermentation, using a new ceramic carrier “APHROCELL” which has a suitable shape for liquid and gas passage. In acetic acid fermentation byAcetobacter cells from ethanol, as a typical example of aerobic fermentation, a productivity of 17.25 g/l h was attained at continuous production of 23 g-acetic acid/l; at an acetic acid concentration around 53 g/l, the productivity was 6.4 g/l h. Thus a marketable vinegar can be obtained continuously by this bioreactor system. Because of the simplicity of the APHROCELL reactor, scale up should be relatively easy.

Acetic acid production by Acetogenium kivui in continuous culture — kinetic studies and computer simulations

This work considers the continuous production of acetic acid by the homoacetogenic and thermophilic bacterium Acetogenium kivui. A mathematical model for the growth kinetics has been developed. The unstructured model for growth and product formation includes product and substrate inhibition as well as maintenance energy effects. The associated model parameters have been identified by non-linear optimization and evidenced experimentally in continuous culture as steady-state data. By using a mineral medium with glucose as the energy and carbon source for the bacteria proper carbon balances are available. The model permits good predictions of steady-state concentrations.

The production of acetic acid from carbon dioxide and hydrogen by an anaerobic bacterium

For the advantageous utilization of carbon dioxide (CO 2), we developed a bioreactor that produces acetic acid from CO 2 using hydrogen (H 2) as the energy source. BR-446 (genus Acetobacterium), which has the highest rate of acetic acid production of the many acetogenic anaerobes isolated in our laboratory, was chosen for the study. Its specific production rate was 3.6 g g −1 h −1. The production rate was affected by the dissolved hydrogen concentration (DH 2) and was found to have a higher value at a low DH 2 level. As the bioreactor, the membrane-filtration type was superior to the immobilized cell type. A constant, continuous acetic acid production for over 1000 h was established using the membrane-filtration type reactor. To further improve productivity, pressurization of the reactor system proved to be effective. Finally, a productivity of 149 g l −1 d −1 was established at high cell density and this value is promising for the future industrial application of this system.

Continuous production of acetic acid using immobilized acetobacter aceti in a three-phase fluidized bed bioreactor

Continuous operation of a three-phase fluidized bed bioreactor using immobilized cells showed that both immobilized and suspended cells contributed to the production of acetic acid. Unlike the rapid decrease in the productivity at dilution rates above 0.25 h −1 in the free cell fermentation, the productivity was little affected by the dilution rate in the immobilized cell fermentation. Theoretical models were proposed for the continuous process. The models approximately agreed with the experimental results. Experimental results and/or theoretical calculations based on the kinetic models showed that suspended cells were important in the production of acetic acid if the solid holdup was small or if gel radius was large. Theoretical calculations showed that an optimal solid holdup or gel size existed at higher dilution rates because of the k L a dependence on solid holdup and particle diameter.

Effects of product inhibition on continuous acetic acid production by immobilized Acetobacter aceti: Theoretical calculations

The behavior of a three-phase fluidized bed bioreactor with immobilized Acetobacter aceti was theoretically studied in the range where product inhibition was present. The maximum productivity appeared at a certain dilution rate, D M, when particles with radii larger than 0.4 mm were used. In this case, suspended cells were important in acetic acid production. The value of D M increased with increasing the gas-liquid volumetric oxygen transfer coefficient, k L a. When small particles with radii of 0.4 mm were used, the productivity was not affected significantly by the dilution rate because immobilized cells were important. Hence, it is desirable to use smaller particles to obtain higher product concentrations and productivity at lower dilution rates.

Continuous production of acetic acid by electrodialysis bioprocess with a computerized control of fed batch culture

The technique of electrodialysis bioprocess, in which acetic acid is continuously removed from the reaction mixture, was applied to the production of acetic acid by Acetobacter aceti. The continuous supply of ethanol and concentrated nutrient solution to the reaction mixture allowed the production of acetic acid to continue for 30 d, while production continued for only 2 d without the electrodialysis system, with or without pH control. During electrodialysis bioprocess, 2221.9 g of acetic acid was produced from 1991.6 g of ethanol during the course of a single culture run of 30 d. The maximum rate of production of acetic acid obtained by electrodialysis bioprocess under the improved electrodialysis conditions was 5.5 g h −1, which was about 1.7 times higher than the rates obtained by bioprocesses without the electrodialysis system. The improvement in the rate of production and yield of acetic acid resulted from the alleviation of the inhibitory effect, on metabolism of the microbe, of the acetic acid that is produced, by maintaining a favorable pH and a low level of acetic acid in the reaction mixture by electrodialysis.

Acetic acid production using a fermentor equipped with a hollow fiber filter module

The continuous production of acetic acid by Acetobacter aceti M23 was carried out using a fermentor equipped with a hollow fiber filter module. The culture continued for 830 h with various dilution rates, which were changed stepwisely from low to high. The final cell concentration was 21.9 g dry cell/L and the maximum productivity of acetic acid was 12.7 g/L.h for the exit acetic acid concentration of about 50 g/L. The productivity was higher than any literature's values surveyed so far. The cell concentration was 62.8 times and the productivity was 4.6 times as high as those of the fermentor without the filter module. The productivity increased with the increase of dilution rate up to 0.3 h(-1). It is interesting to note that the viable cell concentration was kept almost constant about 1.1 x 10(9) cells/ml in spite of the increase of dilution rate. Use of oxygen-rich air was indispensable to establish the high productivity of acetic acid.