Simultaneous acetone butanol ethanol (ABE) fermentation by Clostridium beijerinckii P260 and in situ product recovery was investigated using a vacuum process operated in two modes: continuous and intermittent. Integrated batch fermentations and ABE recovery were conducted at 37 °C using a 14-L bioreactor (7.0 L fermentation volume) containing initial substrate (glucose) concentration of 60 g/L. The bioreactor was connected in series with a condensation system and vacuum pump. Vacuum was applied continuously or intermittently with 1.5 h vacuum sessions separated by 4, 6, and 8 h intervals. A control ABE fermentation experiment was characterized by incomplete glucose utilization due to butanol toxicity to C. beijerinckii P260, while fermentation coupled with in situ recovery by both continuous and intermittent vacuum modes resulted in complete utilization of glucose, greater productivity, improved cell growth, and concentrated recovered ABE stream. These results demonstrate that vacuum technology can be applied to integrated ABE fermentation and recovery even though the boiling point of butanol is greater than that of water.

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 is used to reduce energy requirements. With this technique the heat generated by the compression and partial condensation of the vapors provides the energy for boil up (heat of vaporization) in the flash tank. Thus the energy requirement for the flash fermentation is essentially the electrical power demanded by compressors. Energy for recirculation pumps accounts for approximately 0.5% of the total energy consumption. Small increments in butanol concentration in the beer can have important positive impacts on the energy consumption of the distillation unit. Nonetheless, the energy use of the recovery technology must be included in the energy balance. For a fermentation with a wild-type strain, the total energy requirement for butanol recovery (flash fermentation + distillation) was 17.0 MJ/kg butanol, with 36% of this value demanded by the flash fermentation. This represents a reduction of 39% in the energy for butanol recovery in relation to the conventional batch process. In the case of a fermentation with a hyper-butanol producing mutant strain, the use of the flash fermentation could reduce the energy consumption for butanol recovery by 16.8% in relation to a batch fermentation with the same mutant strain.

The purpose of the present study was to investigate possible methods to enhance the rate of aerobic biodegradation of hydrocarbons (ex-situ treatments). In this work, the bioremediation processes were applied to a sandy soil with a high level of contamination originated from the leakage of a diesel oil underground storage tank at a petrol station. Laboratory scale experiments (Bartha biometer flasks) were used to evaluate the biodegradation of the diesel oil. Enhancement of biodegradation was carried out through biostimulation (addition of nitrogen and phosphorus solutions or Tween 80 surfactant) and bioaugmentation (bacterial consortium isolated from a landfarming system). To investigate interactions between optimizing factors, and to find the right combination of these agents, the study was based on full factorial experimental design. Efficiency of biodegradation was simultaneously measured by two methods: respirometric (microbial CO2 production) and gas chromatography. Acute toxicity tests with Daphnia similis were applied for examination of the efficiency of the processes in terms of the generation of less toxic products. Results showed that all bioremediation strategies enhanced the natural bioremediation of the contaminated soil and the best results were obtained when treatments had nutritional amendment. Respirometric data indicated a maximum hydrocarbon mineralization of 19.8%, obtained through the combination of the three agents, with a total petroleum hydrocarbons (TPH) removal of 45.5% in 55 days of treatment. At the end of the experiments, two predominant bacteria species were isolated and identified (Staphylococcus hominis and Kocuria palustris).

BACKGROUND: Butanol fermentation is product limiting owing to butanol toxicity to microbial cells. Butanol (boiling point: 118• C) boils at a higher temperature than water (boiling point: 100• C) and application of vacuum technology to integrated acetone-butanol-ethanol (ABE) fermentation and recovery may have been ignored because of direct comparison of boiling points of water and butanol. This research investigated simultaneous ABE fermentation using Clostridium beijerinckii 8052 and in situ butanol recovery by vacuum. To facilitate ABE mass transfer and recovery at fermentation temperature, batch fermentation was conducted in triplicate at 35• C in a 14 L bioreactor connected in series with a condensation system and vacuum pump.

This paper presents the techno-economics of greenfield projects of an integrated first and second-generation sugarcane biorefinery in which pentose sugars obtained from sugarcane biomass are used either for biogas (consumed internally in the power boiler) or n-butanol production via the ABE batch fermentation process. The complete sugarcane biorefinery was simulated using Aspen Plus®. Although the pentoses stream available in the sugarcane biorefinery gives room for a relatively small biobutanol plant (7.1-12 thousand tonnes per year), the introduction of butanol and acetone to the product portfolio of the biorefinery increased and diversified its revenues. Whereas the IRR of the investment on a biorefinery with biogas production is 11.3%, IRR varied between 13.1% and 15.2% in the butanol production option, depending on technology (regular or engineered microorganism with improved butanol yield and pentoses conversion) and target market (chemicals or automotive fuels). Additional discussions include the effects of energy-efficient technologies for butanol processing on the profitability of the biorefinery.

Ethyl levulinate is a diesel additive that has received special attention recently due to its potential for production in large quantities from inexpensive feedstocks. Several processes have been developed for the conversion of biomass into levulinic acid and ethyl levulinate, and an economic analysis of these routes would indicate the main hindering factors of their commercialization. This Review focuses on filling this gap in current knowledge by gathering data from scientific papers and patents to create a simulation to analyze processes by focusing on the production of ethyl levulinate in nine countries or regions across the globe. The key indicator to analyze the economic feasibility of ethyl levulinate production is a comparison of its minimum selling price to the local wholesale price of diesel on an energy basis. Processes simulated in Brazil, China, and India presented promising results with feedstocks such as sugarcane bagasse and rice residues. Also, the integration of ethyl levulinate production into existing ethanol plants is a factor that may improve process economics. Overall, this Review specifies key factors in economic and environmental performances of the processes to indicate research topics that could achieve high impact on industrial‐scale processes once matured.

The techno-economics of greenfield projects of a first-generation sugarcane biorefinery aimed to produce ethanol, sugar, power, and n-butanol was conducted taking into account different butanol fermentation technologies (regular microorganism and mutant strain with improved butanol yield) and market scenarios (chemicals and automotive fuel). The complete sugarcane biorefinery with the batch acetone-butanol-ethanol (ABE) fermentation process was simulated using Aspen Plus®. The biorefinery was designed to process 2 million tonne sugarcane per year and utilize 25%, 50%, and 25% of the available sugarcane juice to produce sugar, ethanol, and butanol, respectively. The investment on a biorefinery with butanol production showed to be more attractive [14.8% IRR, P(IRR>12%)=0.99] than the conventional 50:50 (ethanol:sugar) annexed plant [13.3% IRR, P(IRR>12%)=0.80] only in the case butanol is produced by an improved microorganism and traded as a chemical.

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