Flash Fermentation Research Articles

Process design and economics of a flexible ethanol-butanol plant annexed to a eucalyptus kraft pulp mill

This work proposes a strategy, from a process design standpoint, for pulp companies to enter the Brazilian ethanol market. The flexible plant converts eucalyptus-derived glucose to either ethanol or butanol (according to market conditions) and xylose only to butanol production. Depending on the biomass pretreatment technology, Monte Carlo simulations showed that the Net Present Value (NPV) of the flexible plant increases by 20–28% in relation to an ethanol-dedicated plant. Whereas the lower costs of the steam explosion technology turns the investment more attractive (NPV = 184 MMUSD; IRR = 29%), the organosolv technology provides better flexibility to the plant. This work also shows that excessive power consumption is a hurdle in the development of flash fermentation technology chosen for the flexible plant. These results indicate that conventional batch fermentation is preferable if the enzymatic hydrolysis step operates with solids loading up to 20 wt%.

Recycling Of Peneapple Waste Using Lactobacillus Delbroeckii to Lactic Acid

The liquid pineapple waste contain mainly sucrose, glucose, fructose, and other nutrients. It therefore can potentiall be used as carbon source for organic acid fermentation. Recently, lactic acid has been considered to be an important raw material for production of biodegradadable lactace polymer. The experiments weree carried out in shake flash fermentation using lactobacillus delbroeckii. Effect of some parameters such as temperature, initial Ph, initial substrate concentration, yeast extract concentration and fermentation time to the yield have been studied. The highest yield was 85.65% achieved at 40 0C, PH 6.00, 52.2 g/l sugar concentration with 5 g/l yeast extract. There was no significant increasing in lactic acid production was observed if supplementation of yeast extract above 10%.Keyword : lactic acid fermentation, liquid pineapple waste, lactobacillus delbrueckii

Steady-State Simulation of the Strip-Flash Ethanol Fermentation Process

The conventional ethanol fermentaion is a typical inhibitory process, leading to low productivity and yield. A new ethanol fermentation process coupled with gas stripping and vacuum flash, named as strip-flash fermentation, is proposed. The process is provided with the advantages of both stripping fermentation and flash fermentation, and improves the ethanol productivity by increasing the in-situ ethanol removal. And a model of flash-strip fermentation process was established. The theoretically analyses indicate that increasing gas flux and liquid phase recycling ratio can help to enhance productivity and yield of strip-flash fermentation process, and comparison to striping fermentation or flash fermentation, flash-strip fermentation has shown a better productivity. The results has also shown the possibilities of further application and optimization of this process.

Energy Requirements for Butanol Recovery Using the Flash Fermentation Technology

Acetone–butanol–ethanol (ABE) facilities have traditionally presented unattractive economics because of the large energy consumption during recovery of the products from a dilute fermentation broth (∼13 g/L butanol). This problem results from the high toxicity of butanol to microorganisms that catalyze its production. Flash fermentation is a continuous fermentation system with integrated product recovery. The bioreactor is operated at atmospheric pressure and the broth is circulated in a closed loop to a vacuum chamber where ABE is continuously boiled off at 37 °C and condensed afterward. With this technology the beer achieved a concentration of butanol as high as 30–37 g/L. This paper studies the energy requirements for butanol recovery using the flash fermentation technology and its effect on the energy consumption by the downstream distillation system. Compressors are used to remove the vapors from the flash tank, thus maintaining the desired vacuum. The heat recovery technique of vapor recompression i...

Development of real-time state estimators for reaction–separation processes: A continuous flash fermentation as a study case

The development of reliable on-line state estimators applicable to reaction–separation processes is addressed in this work. Artificial Neural Network-based software sensors (ANN-SS) are proposed to allow on-line measurement of key variables, with an estimation algorithm that uses secondary variables as inputs. A continuous laboratory-scale flash fermentation for bioethanol production is considered as a case study. The process consists of three interconnected units: fermentor, filter (tangential microfiltration for cell recycling) and vacuum flash vessel (for the continuous separation of ethanol from the broth). The concentrations of ethanol in the fermentor and of ethanol condensed from the flash are successfully monitored on-line using ANN-SS. The proposed model contributes to improve the understanding of the complex relationships between process variables in the reaction and separation units, which is of major importance to allow the operation of the ethanol production process near its optimum performance.

Optimisation of a continuous flash fermentation for butanol production using the response surface methodology

Factorial design and response surface techniques were used in combination with mathematical modelling and computational simulation to optimise an innovative industrial bioprocess, the production of biobutanol employing the flash fermentation technology. A parametric analysis performed by means of a full factorial design at two levels determined the influence of operating variables on butanol yield and productivity. A second set of simulations were carried out based on the central composite rotatable design. This procedure generated simplified statistical models that describe butanol yield and productivity as functions of the significant operating variables. From these models, response surfaces were obtained and used to optimise the process. For a range of substrate concentration from 130 to 180 g/l, the optimum operating ranges ensure butanol productivity between 7.0 and 8.0 g/l h, butanol yield between 19 and 22%, substrate conversion above 90% and final butanol concentration around 25 g/l.

Dynamics and Control Strategies for a Butanol Fermentation Process

In this work, mathematical modeling was employed to assess the dynamic behavior of the flash fermentation process for the production of butanol. This process consists of three interconnected units as follows: fermentor, cell retention system (tangential microfiltration), and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). Based on the study of the dynamics of the process, suitable feedback control strategies [single input/single output (SISO) and multiple input/multiple output (MIMO)] were elaborated to deal with disturbances related to the process. The regulatory control consisted of keeping sugar and/or butanol concentrations in the fermentor constant in the face of disturbances in the feed substrate concentration. Another objective was the maintenance of the proper operation of the flash tank (maintenance of the thermodynamic equilibrium of the liquid and vapor phases) considering that oscillations in the temperature in the tank are expected. The servo control consisted of changes in concentration set points. The performance of an advanced controller, the dynamic matrix control, and the classical proportional-integral controller was evaluated. Both controllers were able to regulate the operating conditions in order to accommodate the perturbations with the lowest possible alterations in the process outputs. However, the performance of the PI controller was superior because it showed quicker responses without oscillations.

Optimization Strategies Based on Sequential Quadratic Programming Applied for a Fermentation Process for Butanol Production

In this work, the mathematical optimization of a continuous flash fermentation process for the production of biobutanol was studied. The process consists of three interconnected units, as follows: fermentor, cell-retention system (tangential microfiltration), and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The objective of the optimization was to maximize butanol productivity for a desired substrate conversion. Two strategies were compared for the optimization of the process. In one of them, the process was represented by a deterministic model with kinetic parameters determined experimentally and, in the other, by a statistical model obtained using the factorial design technique combined with simulation. For both strategies, the problem was written as a nonlinear programming problem and was solved with the sequential quadratic programming technique. The results showed that despite the very similar solutions obtained with both strategies, the problems found with the strategy using the deterministic model, such as lack of convergence and high computational time, make the use of the optimization strategy with the statistical model, which showed to be robust and fast, more suitable for the flash fermentation process, being recommended for real-time applications coupling optimization and control.

An Alternative Process for Butanol Production: Continuous Flash Fermentation

The objective of this work is to introduce and demonstrate the technical feasibility of the continuous flash fermentation for the production of butanol. The evaluation was carried out through mathematical modeling and computer simulation which is a good approach in such a process development stage. The process consists of three interconnected units, as follows: the fermentor, the cell retention system (tangential microfiltration) and the vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The efficiency of this process was experimentally validated for the ethanol fermentation, whose main results are also shown. With the proposed design the concentration of butanol in the fermentor was lowered from 11.3 to 7.8 g/l, which represented a significant reduction in the inhibitory effect. As a result, the final concentration of butanol was 28.2 g/l for a broth with 140 g/l of glucose. Solvents productivity and yield were, respectively, 11.7 g/l.h and 33.5 % for a sugar conversion of 95.6 %. Positive aspects about the flash fermentation process are the solvents productivity, the use of concentrated sugar solution and the final butanol concentration. The last two features can be responsible for a meaningful reduction in the distillation costs and result in environmental benefits due to lower quantities of wastewater generated by the process.

Technical and Economic Considerations for Various Recovery Schemes in Ethanol Production by Fermentation

Six alternative ethanol recovery processes were investigated from an economic and technical perspective. The processes were evaluated by use of the commercial simulation software Aspen HYSYS 2004.2 with an integrated fermentation model. The six alternatives included two variations of the flash fermentation process as well as various distillation configurations. Certain weaknesses and potential processing improvements were highlighted, and economic and technical targets were set for future comparisons. Distillation with two columns operating at different pressures and distillation with a vapor recompression system for heat recovery were found to be the best alternatives overall. However, from an energy standpoint, the modified flash fermentation process yielded the highest efficiency.

Performance of immobilized Zymomonas mobilis 31821 (pZB5) on actual hydrolysates produced by Arkenol technology.

By applying the Arkenol process using highly concentrated sulfuric acid, various biomass feedstocks, including cedar tree, rice straw, newspaper, and bagasse, were successfully processed and converted into glucose and xylose for fermentation usage in a flash fermentation reactor in which the performance of National Renewable Energy Laboratory's patented rec-Zymomonas mobilis 31821 (pZB5) after immobilization was investigated. The immobilization medium is a photocrosslinked resin made from polyethylene glycols or polypropylene glycols. Recombinant or rec-Z. mobilis used in the study has been shown to efficiently ferment glucose and xylose at a relatively high concentration (12-15%), that is a typical hydrolysate produced from cellulosic feedstocks. The application of immobilized rec-Z. mobilis and flash fermentation technology, together with concentrated acid technology producing a high concentration sugar solution, promises to speed the development of the cellulose-to-ethanol industry.

Surface active properties of the culture filtrates of a Micrococcus species grown on n-alkanes and sugars

The surface active properties of the culture filtrates (from shake flash fermentation for 140 h at 37 ± 1°C) of a species of Micrococcus are described in terms of surface tension, emulsification and foamability using carbon sources, such as n-dodecane, n-tetradecane, n-hexadecane and n-octadecane as the different n-alkanes, and sucrose, fructose, glucose and mannose as the different sugars. The surface tension for the culture filtrate was lowest with dodecane (45·2 mN m −1) followed by tetradecane (49·1 mN m −1), hexadecane (50·8 mN m −1) and octadecane (58·3 mN m −1) among the n-alkanes; for the sugars, sucrose had the lowest value (51·4 mN m −1) followed by fructose (52·8 mN m −1), mannose (57·3 mN m −1) and glucose (57·5 mN m −1). All the n-alkane systems showed 70–80% emulsification of a test mixture composed of equal volumes of kerosene and the respective culture filtrate. But only 84 and 50% of the formed emulsions with tetradecane and dodecane, respectively, remained stable during 48 h of ageing. Although the culture filtrate of fructose showed the highest initial emulsification of 62% among the sugars, almost no decay of the formed emulsion (41%) was observed with that of sucrose. Foamability noted with a single nozzle spurger was appreciable with the sucrose and fructose systems, but negligible with the n-alkane systems.

Novel Repeated Batch Operation for Flash Fermentation System: Experimental Data and Mathematical Modelling

A novel repeated batch operation mode was proposed for ethanol fermentation, where the fermenter beer was periodically exchanged between the fermenter with biomass recycle and the distillation unit, to promote the selective removal of ethanol. Using the mathematical model developed, as based on the experimental results, the optimal operation of the proposed method was shown to attain high performance, with a productivity of about 12 g dm−3 h−1 and a product concentration of 400 g dm−3.

Novel Repeated Batch Operation for Flash Fermentation System: Experimental Data and Mathematical Modelling

A novel repeated batch operation mode was proposed for ethanol fermentation, where the fermenter beer was periodically exchanged between the fermenter with biomass recycle and the distillation unit, to promote the selective removal of ethanol. Using the mathematical model developed, as based on the experimental results, the optimal operation of the proposed method was shown to attain high performance, with a productivity of about 12 g dm−3 h−1 and a product concentration of 400 g dm−3.