Ethanol,the ultimate feedstock

Ethanol appears to be a key factor in the “biomass alternative” to fossil feedstocks for producing fuels and chemicals. If produced at a low enough price relative to crude oil, it and its derivates could account for 159 billion pounds, or 50%, of the US production of synthetic organic chemicals, presently valued at $113 billion. This use would consume 4.2 billion bushels, or about 54%, of the corn crop.

This study evaluated the potential savings in ethanol manufacture to be gained by applying advanced process engineering or genetic engineering of improved organisms, centering on the use of fluidized bed bioreactors operating at high cell densities with immobilized cells of either the Saccharomyces yeast or the bacterium: Zymomonas mobilis.

A new continuous plant could produce at about $1.82/gal based on Zymomonas or $1.97/gal based on the Saccharomyces yeast. The bacterium has a competitive edge as a result of its lower sensitivity to product inhibition.

There appears to be no inherent design limitation to effect the engineering improvements required for the advanced process. In a longer-term, more difficult research effort, it might be possible to reduce or eliminate product inhibition to reduce cost even further.

     

Development of new ethanologenic Escherichia coli strains for fermentation of lignocellulosic biomass

Two new ethanologenic strains (FBR4 and FBR5) of Escherichia coli were constructed and used to ferment corn fiber hydrolysate. The strains carry the plasmid pLO1297, which contains the genes from Zymomonas mobilis necessary for efficiently converting pyruvate into ethanol. Both strains selectively maintained the plasmid when grown anaerobically. Each culture was serially transferred 10 times in anaerobic culture with sugar-limited medium containing xylose, but noselective antibiotic. An average of 93 and 95% of the FBR4 and FBR5 cells, respectively, maintained pLO1297 in anaerobic culture. The fermentation performances of the repeatedly transferred cultures were compared with those of cultures freshly revived from stock in pH-controlled batch fermentations with 10% (w/v) xylose. Fermentation results were similar for all the cultures. Fermentations were completed within 60 h and ethanol yields were 86–92% of theoretical. Maximal ethanol concentrations were 3.9–4.2% (w/v). The strains were also tested for their ability to ferment corn fiber hydrolysate, which contained 8.5% (w/v) total sugars (2.0% arabinose, 2.8% glucose, and 3.7% xylose). E. coli FBR5 produced more ethanol than FBR4 from the corn fiber hydrolysate. E. coli FBR5 fermented all but 0.4% (w/v) of the available sugar, whereas strain FBR4 left 1.6% unconsumed. The fermentation with FBR5 was completed within 55 h and yielded 0.46 g of ethanol/g of available sugar, 90% of the maximum obtainable. Author to whom all correspondence and reprint requests should be addressed. Names are necessary to report factually on available data. However, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA im plies no approval of the product to the exclusion of others that may also be suitable.     

Carboxylate Platform: The MixAlco Process Part 2: Process Economics

The MixAlco process employs a mixed culture of acid-forming microorganisms to convert biomass to carboxylate salts, which are concentrated via vapor-compression evaporation and subsequently chemically converted to other chemical and fuel products. To make alcohols, hydrogen is required, which can be supplied from a number of processes, including gasifying biomass, separation from fermentor gases, methane reforming, or electrolysis. Using zeolite catalysts, the alcohols can be oligomerized into hydrocarbons, such as gasoline. A 40-tonne/h plant processing municipal solid waste ($45/tonne tipping fee) and using hydrogen from a pipeline or refinery ($2.00/kg H₂) can sell alcohols for $1.13/gal or gasoline for $1.75/gal with a 15% return on investment ($0.61/gal of alcohol or $0.99/gal of gasoline for cash costs only). The capital cost is $1.95/annual gallon of mixed alcohols. An 800-tonne/h plant processing high-yield biomass ($60/tonne) and gasifying fermentation residues and waste biomass to hydrogen ($1.42/kg H₂) can sell alcohols for $1.33/gal or gasoline for $2.04/gal with a 15% return on investment ($1.08/gal of alcohol or $1.68/gal of gasoline for cash costs only). The capital cost for the alcohol and gasification plants at 800 tonnes/h is $1.45/annual gallon of mixed alcohols.     

Ethanol production in a membrane bioreactor

Pilot plant trials were conducted in a corn wet mill with a 7000-L membrane recycle bioreactor (MRB) that integrated ceramic microfiltration membranes in a semi-closed loop configuration with a stirred-tank reactor. Residence times of 7.5–10 h with ethanol outputs of 10–11.5% (v/v) were obtained when the cell concentration was 60–100 g/L drywt of yeast, equivalent to about 10⁹−10¹⁰ cells/mL. The performance of the membrane was dependent on the startup mode and pressure management techniques. A steady flux of 70 L/(m²·h) could be maintained for several days before cleaning was necessary. The benefits of the MRB include better productivity; a clear productstream containing no particulates or yeast cells, which should improve subsequent stripping and distillation operations; and substantially reduced stillage handling. The capital cost of the MRB is $21–$34/(m³·yr) ($0.08–$0.13/[gal·yr]) of ethanol capacity. Operating cost, including depreciation, energy, membrane replacement, maintenance, labor, and cleaning, is $4.5–9/m³ ($0.017–$0.034/gal) of ethanol.     

Preliminary estimate of the cost of ethanol production for ssf technology

The Solar Energy Research Institute (SERI) recently completed a detailed engineering and economic analysis of the simultaneous saccharification and fermentation (SSF) based wood-to-ethanol process. The reference-case design was based on a plant capacity of 1920 dry t/d and a wood cost of $42/dry t. For this case, the preliminary estimate of the production cost of the ethanol product is about $1.22/gal. The combined effects of optimizing SSF enzyme loading, increasing plant capacity to 10,000 dry t/d, and reducing wood cost to $34/dry t are to reduce the preliminary estimate of the production cost to about $0.95/gal. Other technological improvements may further reduce the production cost. Certain technical assumptions, inherent in the analysis, are being investigated further.

     

Ethanol production from glucose and xylose by immobilized Zymomonas mobilis CP4 (pZB5)

Fermentation of glucose-xylose mixtures to ethanol was investigated in batch and continuous experiments using immobilized recombinant Zymomonas mobilis CP4(pZB5). This microorganism was immobilized by entrapment in κ-carrageenan beads having a diameter of 1.5–2.5 mm. Batch experiments showed that the immobilized cells cofermented glucose and xylose to ethanol and that the presence of glucose improved the xylose utilization rate. Batch fermentation of rice straw hydrolysate containing 76 g/L of glucose and 33.8 g/L of xylose gave an ethanol concentration of 44.3 g/L after 24 h, corresponding to a yield of 0.46 g of ethanol/g of sugars. Comparable results were achieved with a synthetic sugar control. Continuous fermentation experiments were performed in a laboratory-scale fluidized-bed bioreactor (FBR). Glucose-xylose feed mixtures were pumped through the FBR at residence times of 2–4 h. Glucose conversion to ethanol was maintained above 98% in all experiments. Xylose conversion to ethanol was highest at 91.5% for a feed containing 50 g/L of glucose and 13 g/L of xylose at a dilution rate of 0.24/h. The xylose conversion to ethanol decreased with increasing feed xylose concentration, dilution rate, and age of the immobilized cells. Volumetric ethanol productivities in the range of 6.5–15.3 g/L·h were obtained. The improved productivities achieved in the FBR compared to other bioreactor systems can help in reducing the production costs of fuel ethanol from lignocellulosic sugars. This article has been authored by a contractor of the US go vernment under contract DE-AC05-96OR22464. Accordingly, the US government retains a nonexclusive, royaltyfree license to publish or reproduce the published form of the contribution, or allow others to do so, for US government purposes.     

Fermentation and costs of fuel ethanol from corn with quick-germ process

The Quick-Germ process developed at the University of Illinois at Urbana-Champaign is a way to obtain corn oil, but with lower capital costs than the traditional wet-milling process. Quick-Germ has the potential to increase the coproduct credits and profitability of the existing dry-grind fuel ethanol process, but the fermentability of the corn remaining after oil recovery has not been tested. Therefore, a series of pilot scale (50 L) fermentations was carefully controlled and monitored with unique methods for standard inoculation and automatic sampling. It was found that the concentration of suspended solids was significantly reduced in the Quick-Germ fermentations. When compared at the same concentration of fermentable sugars, the fermentation rate and yield were not statistically different from controls. When Quick-Germ was integrated into a state-of-the-art dry-grind fuel ethanol process, computer simulation and cost models indicated savings of approx $0.01/L of ethanol ($0.04/gal) with the Quick-Germ process. Additional savings associated with the lower suspended solids could not be quantified and were not included. However, the savings are sensitive to the price of corn oil. Mention of brand or firm name does not constitute an endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned.     

Potential Enzyme Cost Reduction with the Addition of Surfactant during the Hydrolysis of Pretreated Softwood

The potential economic benefits of surfactants addition on enzymatic hydrolysis of steam-exploded lodgepole pine (SELP) and ethanol-pretreated lodgepole pine (EPLP) were investigated in this study. Free cellulase readsorption on fresh substrate was used to recover and recycle cellulase enzymes during the hydrolysis of SELP and EPLP substrate. Supplementing Tween 80 during the hydrolysis could facilitate enzyme recycling for EPLP substrate. A logarithmic correlation was established between surfactant concentration and free cellulase content after lignocellulosic hydrolysis, which was used to compute enzyme cost savings over various Tween 80 concentrations. A simple economic analysis of enzyme cost savings versus the cost of surfactant was undertaken. The results indicated that the addition of Tween 80 (priced at US $0.25/kg) during the hydrolysis of the EPLP substrate could save 60% of the total enzyme cost at concentrations in the 0.025% to 0.2% range. The addition of Tween for the hydrolysis of the SELP substrate significantly reduced the material cost by 24% per 1 gal of ethanol produced, and the ethanol production cost could be reduced by 8.6% with the addition of Tween and enzymes recycle for the hydrolysis of SELP substrate. A schematic concept of recycling enzyme and surfactant was also presented with a recirculation of process streams during hydrolysis. Further analysis indicated a 66% reduction in total enzyme cost could potentially be achieved under the concept.     

Biomass conversion to mixed alcohol fuels using the MixAlco process

The MixAlco process is a patented technology that converts any biodegradable material (e.g., sorted municipal solid waste, sewage sludge, industrial biosludge, manure, agricultural residues, energy crops) into mixed alcohol fuels containing predominantly 2-propanol, but also higher alcohols up to 7-tridecanol. The feed stock is treated with lime to increase its digestibility. then, it is fed to a fermentor in which a mixed culture of acid-forming microorganisms produces carboxylic acids. Calcium carbonate is added to the fermentor to neutralize the acids to their corresponding carboxylate salt. The dilute (−3%) carboxylate salts are concentrated to 19% using an amine solvent that selectively extracts water. Drying is completed using multi-effect evaporators. Finally, the dry salts are thermally converted to ketones which subsequently are hydrogenated to alcohols. All the steps in the MixAlco process have been proven at the laboratory scale. A techno-economic model of the process indicates that with the tipping fees available in New York ($126/dry tonne), mixed alcohol fuels may be sold for $0.04/L ($0.16/gal) with a 60% return on investment (ROI). With the average tipping fee in the United States rates ($63/dry tonne), mixed alcohol fuels may be sold for $0.18/L ($0.69/gal) with a 15% ROI. In the case of sugarcane bagasse, which may be obtained for about $26/dry ton, mixed alcohol fuels may be sold for $0.29/L ($1.09/gal) with a 15% ROI.     

Sodium and silver phosphate glasses doped with chlorides of Fe,Mn and Zn

A number of samples of sodium and silver phosphate glasses doped with various compositions of some transition metals viz. iron, manganese and zinc chlorides alongwith undoped samples of sodium and silver phosphate glasses were synthesized and characterized by X-ray diffraction, IR spectral, electrical conductivity and differential scanning calorimetry (DSC). The glass transition temperature (T _g) and crystallization temperature (T _c) values obtained from DSC curves were found to increase with increasing concentration of the dopant Fe/Mn/Zn chlorides in both sodium and silver phosphate glasses and the following sequence is observed: T _g(–FeCl₃)>T _g(–MnCl₂)>T _g(–ZnCl₂) T _c(–FeCl₃)>T _c(–MnCl₂)>T _c(–ZnCl₂) The increase in T _g and T _c values indicate enhanced chemical durability of the doped glasses. The electrical conductivity values and the results of FTIR spectral studies have been correlated with the structural changes in the glass matrix by the addition of different transition metal cations as dopants.     

Inclusion compounds of cystostatic active (C5H5)2VCl2 and (CH3C5H4)2VCl2 with α-, β- and γ-cyclodextrines: Synthesis, EPR study and microbiological behavior toward Escherichia coli

The inclusion of vanadocene dichloride (VDC) and 1,1′-dimethyl vanadocene dichloride (MeVDC) into cyclodextrines (α-CD, β-CD and γ-CD) was studied by EPR spectroscopy. It was found that VDC and MeVDC with β-CD and γ-CD form true inclusion compounds, but with α-CD, VDC and MeVDC gave only fine dispersion mixtures. The inclusion was validated by anisotropic EPR spectra of solid samples. In addition, the antimicrobial was validated by anisotropic EPR spectra of solid samples. In addition, the antimicrobial behavior (against E. coli) of each of the complexes was determined. It was established that not only did VDC and MeVDC cause elongation of E. coli, but also the new vanadocene inclusion complexes were effective in this regard.     

Hydride generation atomic absorption spectrometry with insitu graphite tube trapping for the determination of Se (IV) and Se (VI) in baltic sea water samples

This paper reports the results of an optimisation study for a procedure to determine the total selenium and its inorganic species, Se(IV) and Se(VI) using atomic absorption spectrometry combined with hydride generation and in-situ trapping of the analyte on the inner walls of the graphite tube. With the use of the proposed modification, a detection limit (3σ) of 0.018 ng/ml is achieved. This paper presents exemplary results, according to the proposed procedure, for selenium determination in samples of marine water. The concentrations of selenium in the samples ranged from <0.02 ng/ml to 0.16ng/ml of Se(IV) and from <0.02 ng/ml to 0.10 ng/ml of Se(VI).     

Reactions ofn-hexane andn-nonane on Pt catalysts and hydrogenating off hydrocarbonaceous adspecies after reaction

n-Hexane andn-nonane were reacted on Pt black, 6% Pt/SiO₂, 0.8% Pt/KL zeolite and a 0.6% industrial Pt/Al₂O₃ catalyst. Selectivities were compared at ∼10% conversion. After reaction, the catalyst was exposed to H₂ and the hydrocarbons leaving the catalysts were analyzed. The amount of hydrocarbons left the catalysts decreased in the sequence Pt black>Pt/SiO₂>Pt/KL>Pt/Al₂O₃. The composition of removed hydrocarbons gave important—although indirect—information on the possible state of “hydrocarbonaceous deposits” during catalysis.     

Effect of C∶N molar ratio on monomer composition of polyhdroxyalk anoates produced by Pseudomonas mendocina 0806 and Pseudomonas pseudoalkaligenus YS1

Polyhydroxyalkanoates (PHAs) are biodegradable polymers produced by bacteria. In this study, the effect of C∶N molar ratio on the monomer composition of PHAs was investigated, including medium chain length PHA produced by Pseudomonas mendocina 0806 and PHA blends consisting of monomers of 3-hydroxybutyrate and medium chain length hydroxyalkan⇘te produced by Pseudomonas pseudoalkaligenus YS1. It was observed that there were some fixed ranges of C∶N molar ratio that affect the monomer composition of PHA independently of the substrate. For strain 0806, the ranges were C∶N <20, 20<C∶N<200, and C∶N>200. The monomer composition was constant among these ranges when using glucose and octanoate as the sole substrate. For strain YS1, the ranges were C∶N<20, 20<C∶N<45, and C∶N>45. These results are useful for controlling monomer composition in PHA production.     

Quantitative HPLC Determination and Stability Studies of Pyridostemin in Extracts and Water Dispersible Granule Formulations of Stemona curtisii

A reversed-phase high-performance liquid chromatographic method has been developed and validated for the determination of pyridostemin, the major pesticidal alkaloid found in Stemona curtisii. This methodology was applied to the investigation of plant extracts and water dispersible granule formulations. Stability indicating procedures have also been carried out. The chromatographic separation was on a C₁₈ column with a mixture of acetonitrile–water–triethylamine (30:70:0.12, v/v/v), using UV detection at 300 nm. Validation procedures showed that the method was specific, accurate and precise. The response was linear over a range of 5–25 μg mL⁻¹ with recoveries in the range of 98.28–102.85%. The RSD for intra- and inter-day precision were <0.72 and <1.29%, respectively. Extraction of plant material with dichloromethane gave a significantly higher pyridostemin content in the crude extracts when compared with extractions in methanol. Partial purification of the crude extracts by silica gel column chromatography was used to concentrate the mixture about fourfold. Degradation behavior of pyridostemin in the partially purified extracts followed first-order kinetics. The main pathways for its decomposition were base hydrolysis and oxidation.     

Chemometric study of soil analysis data

The present paper deals with chemometric interpretation of soil analysis data collected from 31 sampling sites in the region of Kavala and Drama, Northern Greece. The determination of 16 different chemical and physicochemical characteristics is principally needed for prognosis of the land treatment and fertilizing. The study carried out indicates that the application of multivariate statistical approaches could reveal new and specific information about sampling sites. It has been found that they could be divided into four general patterns: pattern 1 contains dominantly inorganic and alkaline soil samples from semi-mountainous regions in close proximity to the seacoast; pattern 2 indicates the same soil sample type and regional location as pattern 1 but is far from the coastal line; pattern 3 includes samples from sites from the plains with organic and alkaline soils with close proximity to the coast; pattern 4 resembles pattern 3 as soil type but involves samples from sites far from the shore. Further, six latent factors were identified, conditionally named “structural”, “acidic”, “nutritional”, “salt”, “microcomponents” and “organic”. Finally, an apportioning procedure was carried out to find the source contributions in the measured analytical values. In this way the routine estimation of the soil quality could be improved.     

Ternatine, a new diterpene alkaloid fromDelphinium ternatum

A new alkaloid, ternatine (C₂₄H₃₃NO₅), was isolated from aerial parts of theDelphinium ternatum plant. According to the¹H,¹³C NMR, IR, and mass spectra of the base and its triacetate, ternative was assumed to have the structure of 4β-methyl-7α-isobutyryloxy-11α,15β,19β-trihydroxyhetisane. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 187–189, January, 1997.     

A new C-glucoside from <Emphasis Type="Italic">Commelina communis</Emphasis>

A new C-glucoside, 3,4-epoxy-5-hydroxymethyl benzoate 2-C-β-glucoside (1), together with a known alkaloid, 1H-indole-3-carbaldehyde (2), were isolated from the whole plant of Commelina communis L. The structures of these compounds were determined by 1D, 2D NMR and MS techniques. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 51–52, January–February, 2009.     

Determination of inorganic oxyhalides in drinking water by on-line coupled capillary isotachophoresis— capillary zone electrophoresis

Some oxyhalides can be found in drinking waters as inorganic disinfection byproducts. An on-line coupled capillary isotachophoresis—capillary zone electrophoresis (CITP-CZE) method was developed for the analysis of chlorate, chlorite and bromate in water. The optimized CITP-CZE electrolyte system consisted of the following: 10 mM—HCl+20 mM—β-Alanine (leading electrolyte), 5 mM—succinic acid (terminating electrolyte), and 10 mM—succinic acid +5 mM—β-Alanine +0.1% HPMC (carrier electrolyte). A clear separation of oxyhalides from other components of drinking water was achieved within 25 min. Method characteristics, i.e., linearity (0–200 ng/mL), accuracy (88–110%), intra-assay (3–5%), quantification limit (5–15 ng/mL), and detection limit (2–5 ng/mL), were determined. Minimum labor requirements, sufficient sensitivity and low running cost are important attributes of this method. It was found that the developed method is useful for the routine analysis of oxyhalides in water.