Saturday, November 29, 2008

Downstream processing of biobased succinic acid (3)

Approach III: Ammonium-Based SA Purification: Extraction and Crystallization
(Huh, et al. Process Bio. 41(2006)1461-1465

•Key points for the process
–SA crystallizer: Succinate ion is protonated by ammonium bisulfate to form ammonium sulfate and SA. SA crystallizes due to its low solubility at pH 1.5-1.8 (optimal yield generated)
–Methanol purification: SA is advantageously dissolved in methanol but sulfates relatively insoluble in methanol
–Thermal craker: Ammonium sulfate cracks to produce ammonium and ammonium bisulfate, which can be reused.

–Minimal use of additional reagents
–Produce virtually no waste by-products
–Permit internal recycle of the base and acid

It is recommended!

Friday, November 28, 2008

Biobased succinic acid players

According to Huw Kidwell, the current worldwide use of succinic acid is around 20,000 to 30,000 tonnes per year and this is on the increase by around 10 per cent a year, which attracts industrial interests in biobased sugar platform succinic acid production. This is a big cake and who will be the first to have the market share?
Bioamber, a joint venture by ARD and DNP develop a commercially viable technology for the production of succinic acid by fermentation of various renewable feedstocks. It will use carbon dioxide from the ethanol plant for its fermentation process, according to the company. The plant will have an annual capacity of 5,000 metric tons, producing succinic acid, ethanol and biodiesel.

2. MBI International

MBI, established in 1981 by the Michigan High Technology Task Force, has a history of developing biobased chemicals and agricultural feedstocks into chemicals derived from fermentation processes. In 1996, the company patented the unique bacterium it isolated for production of succinic acid from sugars. MBI is actively seeking commercial partnerships for its biobased succinic acid platform.
BioEnergy International, LLC is a privately-held, science and technology company in the development and commercialization of next generation biorefineries for the production of high-value bio-based chemicals (such as succinic acid) and fuels from renewable feedstock through the use of its proprietary biocatalyst technology.
Royal DSM N.V., and ROQUETTE have joined forces to implement and commercialize the fermentative production of biorenewable succinic acid, which – amongst other applications - opens the possibility to produce bio-based performance materials. By the end of 2009 a demonstration plant in Lestrem (France) will be operational.

Downstream processing of biobased succinic acid (2)

Approach II: A Combination of Electrodialysis and Water Splitting
(Glassner et al. US Patent, 5,143,834)

1. Key points for the process
–Use conventional electrodialysis to recover and concentrate the succinate salt from a whole broth containing cells and impurities
–A water-splitting electrodialysis to convert the succinate salt to succinic acid and base
–Treatment with ion-exchangers to remove charged impurities from succinic acid

2. Advantages
–Allow cell-containing whole broth to be sent directly to electrodialysis without pretreatment such as filtration and centrifuge
–Preferential recovery of desired succinate salt over acetate through the membranes

–High cost associated with electrodialysis such as membrane costs and electrical energy costs

Tuesday, November 25, 2008

Downstream processing of biobased succinic acid (1)

Unlike ethanol, which you can just distill away from other components, you cannot do that with succinic acid! Downstream processing is key steps to commercialize biobased succinic acid production. The broth of succinic acid (SA) fermentation has a lower SA concentration (~60 g/L) with the side products such as acetic acid, meleic acid, formic and lactic acid etc. It is a major factor involved in industrial scale production using fermentation due to the cost (60%) involved in downstream processing to concentrate and purify the products.
There are techniques needed for pure SA production and efficient recovery process. SA fermentation usually proceeds best at an approximately neutral pH (6.0-7.0), but acid products will eventually lower the pH,therefore,the pH of the broth needs to be rained and maintained by addition of base; The added basic compounds generally react with the acid to form salts rather than the desired free acid product itself. The traditional succinic acid recovery method is based on precipitation and crystallization technology, acidification by ion-exchange resins and crystallization process:
–Removal of insoluble materials such as dead cells
–Concentrate the fermentation broth
–Crystallization and filtration
–Purification of the acidified product by ion-exchange resins

Approach I: Ca-Based SA Separation: Precipitation and Washing
(Datta et al. US Patent, 5, 168,055)

Key process-related problems
–Separation of dilute product streams and the related cost of recovery
–Elimination of the salt waste from current purification process
–The reduction of inhibition to the product of the fermentation itself
–Separation of other acidic by-products such acetic acid, formic acid, lactic acid, citric acid,etc.

Product related problems
- one mole of product ends up one mole of gypsum, which is a by-product with little value
- Odor and color contamination
- Comsumption of CaO, CaOH, and H2SO4, which are not regenerated within the process

Monday, November 24, 2008

A review: Production of succinic acid by bacterial fermentation

A review paper titled "Production of succinic acid by bacterial fermentation" was published in "Enzyme and Microbial Technology 39 (2006) 352–361" .This paper reviews processes for fermentative succinic acid production, especially focusing on the use of several promising succinic acid producers including Actinobacillus succinogenes, Anaerobiospirillum succiniciproducens, Mannheimia succiniciproducens and recombinant Escherichia coli.

Breakthrough: convert lignin to biofuels

Scientists achieve chemical breakthrough that converts sawdust into biofuel, reported by Newspost online.

Sunday, November 23, 2008

Integrated biorefinery for SA and bioethanol production

Since SA fermentation needs CO2 input and biothanol fermentation produce CO2 as a main product, a integrated biorefinery has been suggested for the biorefinery, i.e. Integrating the succinate and the ethanol fermentations would decrease carbon lost as waste CO2 and produce three commercial products; ethanol, SA and diethyl succinate as shown below:

Saturday, November 22, 2008

Chemical firms show growing interest in bio-based production.

"Renewable Feedstocks are in the Bag", written by Bill Gerards, Contributing Editor of

The new fate of biofuels

The oil price has drop to the point where current bioethanol production from biomass is not profitable. The recent sharp up-and-down of the petroleum oil price is unusual and does not look like the change of oil supply-and-demand equilibrium. I believe the oil price will be back soon and the efforts towards biofuels production need to stay the right track.

Succinic acid production

Traditionally, SA can be synthesized through chemical process from maleic anhydride through n-butane using petroleum as starting material; the high raw material cost of maleic anhydride limits the use of succinic acid for a wide range of applications. Recently efforts have been focusing on produce SA via fungal or bacterial fermentations through the TCA reactions because the increased market expected to come from the synthesis of biodegradable polymers; polybutylene succinate (PBS) and polyamides (Nylon®x,4) and various green solvents.

During biochemical pathways for SA synthesis, bacteria used mainly utilize the phosphoenolpyruvate (PEP) carboxylation reaction and the reductive arm of the TCA cycle. It requires CO2 input; Formation of by-products such as acetic, formic and lactic acid can be a major problem, but will be solved by improving the microbs and the fermentation conditions. Theoretically, redox balance gives 1.714 mol succinate per mol glucose or 1.12 g succinate each gram glucose.

The manufactering cost is mainly affected by succinic acid yield, productivity, raw material cost and utilization, and product recovery method. The technological efforts still need to reduce the cost of both aerobic and anaerobic fermentations – nutrients and carbon feedstocks; improve the robustness of fermentations, increase the productivity of organisms – a minimum of 2.5 g/(L. h) is needed for the process to be economically competitive; and ferment both 5 and 6 carbon sugars.

Where are we for succinic acid commercialization?

"The Quest to Commercialize Biobased Succinic Acid" written by By Jessica Ebert from Biomass Magazine.

Friday, November 21, 2008

Biofuel education

Many universities have developed programs for biofuel education. Since next 5-10 years, biofuels will have big impact on the daily life of common people, common people can not ignore it, neither avoid it. So, there is really need more biofuels public education programs.

Thursday, November 20, 2008

The Integrated Forest Product Biorefinery (2)

A modern pulp mill employs about 70% of the technologies needed by a biorefinery and provides a means of “fast tracking” the development of innovative biorefinery technologies.

Although the conversion of wood cellulose into a sugar-rich process stream has been extensively studied, it is frequently overlooked that economic factors favor the manufacturing of paper over biofuels/biochemicals, making the practical success of this approach doubtful. In sharp contrast, wood glucomannans are rapidly extracted and degraded in the Kraft pulping process to isosaccharinic acids and not utilized as a significant part of pulp fibers. Degraded glucomannans end up as energy during black liquor gasification. Because of the relatively low heating value of hemicellulose, it contribute only 15-20% of heating value to black liquor. Therefore, hemicellulose is worth more as ethanol/chemicals than as energy.

Energy values of different fuels in an IFBR
Fuel Heating Value(GJ/MT)
Oil 43.5
Biomass (20% H2O) 15
Black liquor (80% ds) 12.6
Lignin 26.9
Carbohydrates 13.6

Hemicellulose (mainly xylose in hardwood, grass and agricultural crop residuals and glucomannan in softwood) comprise ~ 5 – 26% of biomass and are an under utilized biochemical resource that could be readily converted to bioethanol/biochemicals. The removal of these hemicellulose prior to kraft pulping should improve the overall kraft pulping process by reducing cooking times and improving chemical impregnation. These process benefits will facilitate practical implementation of this biorefinery concept.

Prior to Pulping Approach:
  • Uses hot water extraction vessels to extract hemicelluloses
  • Acetic acid is separated, and sugars are fermented to fuel grade ethanol with known processes as shown below
  • Removing the “sugars”improves throughput potential of existing operations such as pulping and chemical recovery
  • Ethanol is at the low end of potential products
  • Development of further value includes biorefining systems to produce high-value chemicals as well as biodiesel and ethanol

Post-Pulping Approach:
• Extraction of cellulose- and lignin-derived chemicals from black liquor
• Recovery of tall oil soap and extractives from black liquor
Gasification of black liquor residuals, wood waste, and other biomass to produce syngas
• Conversion of syngas to methanol, DME, ethanol, Fischer-Tropsch fuels, etc.

Wednesday, November 19, 2008

The fate of biomass

Biomass has been traded like a commodity as solid biofuels within Europe, including wood chips, wood pellets, briquettes, logs, sawdust and straw bales etc. The standard and markets have been established.

However, biomass has been utilized and will be utilized more as feedstocks for the production of liquid fuels through thermochemical and biological conversion in the world.

Will be a competition for both fuels? Whatever, biomass will suddenly become a hot commodity like corn when biofuels become a hot industry.

The Integrated Forest Product Biorefinery (1)

It has been generally acknowledged, that North America’s forest products industry must consider new manufacturing strategies and new products if they want to stay competitive in the global market place. One of the industry’s strength is the fact that it is one of the few nationally based industries that have the necessary skill set and infrastructure available to collect and process sufficient biomass for the rapid development and commercialization of biorefining technologies in the near future. The development of biorefining technologies leveraged with pulp manufacturing would be one of the few technological solutions that would avoid the $0.5-1 billion of new investment costs needed to develop a biorefinery capable of processing 1,000-2,000 tons of wood a day.
The forest product industry is part of the manufacturing sectors that convert wood into high-value products and can contribute about 5% to current U.S. GDP. It frequently provides employment in many rural one-industry towns critically dependent upon their natural wood resource such as in the states of Georgia, Wisconsin, Michigan, Maine, Alabama, Arkansas, etc. Unfortunately, the recent downturn in the pulp and paper industry and composite wood products sector has resulted in permanent closure of many pulp and board manufacturing facilities. As a reult, these plant closures put those states that are dependent upon the forest industry as a main contributor to economic health and employment in an extrem difficulty situation. The loss of pulp mills has led to substantial increases in rural unemployment and reductions in future economic growth.
Recently there is a renewed interest in the production of biofuels and bio-based chemicals from lignocellulosics because they are derived from a renewable and carbon-neutral feedstock contrary to their fossil fuel-based counter parts. In addition, oxygen rich chemicals are in principle easier to make from the sugar components present in lignocellulosics by mostly fermentation routes, as compared to complex catalytic conversions of oxygen deficient feedstocks such as oil or natural gas. Within these challenging economic conditions tremendous new opportunities are developing in the forest product industry. The conversion of the fuels industry from hydrocarbon-based technologies to carbohydrate-based would dramatically improve rural employment opportunities, enhance national security, and improve environmental performance, including reductions in CO2 emissions, which is so-called "carbohydrate economy".
Traditionally, pulp mills have one main product stream: From wood chips to pulp fiber (and thermal energy). When looking at this industry, it is not difficult to find that pulp mill is a Natural home for the forest product biorefinery because the pulp and paper industry is the largest handler of forest residues (lignocellusics) and has put tons of money to build the infrastructure such as boiler house, generators, control rooms, pipe bridges, water and effluent stations, warehouses, woodyards, wood procurement, storage tanks. These infrustructure can be used or co-utilized, which will save ~ 35% of capital cost compared to new greenfield construction. This industry already has hundreds of highly trained technical professionals that are available for cellulosic biorefineries. The co-production and process integration can reduce allocated production cost. The second product stream such as bioethanol and other biochemicals can add additional revenue to the industry. This is a new concept: The Integrated Forest Product Biorefinery (IFPB), which has two product steams: From wood chips to pulp fibers and biofuels/biochemicals.

One-Step Process Developed for Polylactic Acid Production

According to Japan Chemical Week, Japanese scientists have developed technology for the synthesis of polylactic acid (PLA) from biomass in one step.
In the conventional process of making PLA, starch from plants like corn, sugarcane or potatoes undergoes microbial fermentation and complicated processes to form cyclic lactide monomers, which are then subjected to ring-opening polymerization in the presence of a metallic catalyst and heat to obtain the polymer. The article reports PLA manufacturers have been aggressively pursuing simpler, more-efficient process technology. In addition to being simpler than current processes, this technology is also able to produce specific PLA enantiomers.
The technology has reportedly been successfully patented, but the details of the technology were not provided.
Cited from "Industrial Biotech Innovation Report"

Stable Enzyme Solutions

A new patent about "STABLE ENZYME SOLUTIONS AND METHOD OF MANUFACTURING" relating to the stabilization during storage has been assigned to Novozymes A/S.

Superactive cellulase formulation using cellobiohydrolase-1 from Penicillium funiculosum

A new patent (US 7,449,550) was assigned to Alliance for Sustainable Energy LLC for the new invention on developing a superactive cellulase formulation using cellobiohydrolase-1:

"Purified cellobiohydrolase I (glycosyl hydrolase family 7 (Cel7A) enzymes from Penicillium funiculosum demonstrate a high level of specific performance in comparison to other Cel7 family member enzymes when formulated with purified EIcd endoglucanase from A. cellulolyticus and tested on pretreated corn stover. This result is true of the purified native enzyme, as well as recombinantly expressed enzyme, for example, that enzyme expressed in a non-native Aspergillus host. In a specific example, the specific performance of the formulation using purified recombinant Cel7A from Penicillium funiculosum expressed in A. awamori is increased by more than 200 percent when compared to a formulation using purified Cel7A from Trichoderma reesei."

Succinic Acid

Succinic acid (SA), also known as amber acid or butanedioic acid, is a dicarboxylic acid having the molecular formula of C4H6O4. After its first purification of succinic acid from amber by Georgius Agricola in 1546, it has been produced by microbial fermentation for the use in agricultural, food and pharmaceutical industries, i.e. one of the fermentation end-products of anaerobic metabolism (Fig.1).

Fig. 1. Biochemical Pathways for SA synthesis

Currently, most of commercially available succinic acid is produced by chemical process, in which liquefied petroleum gas or petroleum oil is used as a starting material.

Succinic acid can be used as a precursor of many industrially important chemicals and considered by US-DOE as one of twelve top chemical building blocks that can be manufactured from biomass (Fig. 2.).

Fig. 2.

Tuesday, November 18, 2008

Molecular-weight cut-off for membrane separation

Reverse osmosis or nano-filtration membranes with differing pore sizes are often selected to separate phenolic compounds and sugar degraded by-products in the hydrolyzates. Usually, the pore size of a membrane is given by the molecular-weight cut-off instead of pore diameter. The molecular weight of the typical chemical compounds in the liquors under studies is shown below:

Compounds MW
Hexoses 180.2
Pentoses: 150.1
Acetic acid 60.1
Furfural 96.1
HMF 110.1

Saturday, November 15, 2008

Negative effect of biofuel production on global warming reduction

There is a report on negative effect of biofuel production on global warming:

This new study results show N2O release from agro-biofuel production negates global warming reduction by replacing fossil fuels.

"When the extra N2O emission from biofuel production is calculated in “CO2-equivalent” global warming terms, and compared with the quasi-cooling effect of “saving” emissions of fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), depending on N fertilizer uptake efficiency by the plants, can contribute as much or more to global warming by N2O emissions than cooling by fossil fuel savings."

Pump 'gas' from biomass: the journey from dream to reality (10)

A three-step plan on nearly parallel track needed to make biofuel production affordable and sustainable: R&D, demonstration, and deployment. This report summarized these plans to address the issue to bring biofuels to pump: an aggressive plan for ending Americana's oil dependence.

Thursday, November 13, 2008

Detoxification: a key step in the biorefinery process (2)

The detoxification for bioethanol production from lignocellulosic biomass needs to reduce trace containment levels to the following concentrations: lignin: < 1%; acetic acid: < 1 g/L; furfural:< 0.5 g/L; HFM: <0.8 g/L; formic acid:<5g/L.

Tuesday, November 11, 2008

Detoxification: a key step in the biorefinery process (1)

It has been recognized that hemicellulose from wood furnish can be pre-extracted using hot water, acid, alkali, and organic solvent and then converted into bioethanol by fermentation. Typically, the wood extracts from hot-water or organo-aqueous extraction consist of monomeric and oligomers of sugars (hexoses and pentoses), acetic acid, methanol, aromatic compounds, and other low molecular-weight (MW) extractable substances. However, the presence of various lignins derived components and phenolics interferes with the enzyme adsorption and function to the target substrate in the subsequent hydrolysis process, as well as potentially toxic to the micro-organisms for fermentation. In addition, small molecules such as acetic acid, furfural and hydroxyl methylfurfural (HMF) produced from these processes are also potent inhibitors for fermentation. Obviously, separation of the toxic products from the pre-extracted liquor mixture is a key step in the biorefinery process.
There are several methods which can be used for separation purpose, including striping, distillation, centrifugation, chemical separation, and filtration. Striping off volatile compounds can be performed right after the extraction stage but doesn’t remove the lignin derived compounds. Multiple fractional distillation is often proposed but this is an energy-intensive operation with high capital cost, especially for the separation of chemicals that can form azeotropes such as water and acetic acid. Chemical separation requires additional chemicals to bond the target compounds such that they can be separated more easily. However it is usually hard to achieve the desirable product stream with high purity for a multiple compound liquor mixture and this also requires additional chemical cost and recovery, which is not practical for a massive production. Centrifugation obviously can not work for the wood extracts or pulping spent liquor. Filtration is a simple physical method that can be easily performed with fair capital cost and most importantly, it can preserve the values of the separated streams. Typically, membrane filtration with specific pore size (molecular weight cut-off) can be used to separate different molecules in the extract liquor. But its captial and operation cost, regeneration are the trade-off.

Sunday, November 9, 2008

More about lignocellulosic biomass pretreatments

Currently biomass pretreatment is still a necessary step to establish a cheap sugar platform for bioethanol and biochemical products. An ideal pretreatment technology should target the three basic requirements: simple process,cost effective, and high sugar recovery.

If we examine all the pretreatment technologies published so far, few of them meet such fundamental requirements. To design a pretreatment approach, a fundamental understanding of biomass cell structure,cellulose and lignin chemistry,and transport phenomenon is necessary. The following picture has been used and cited widely to visually demonstrate the effect of pretreatment for those non-scientific people. Unfortunately, I am afraid there is somewhat misleading. People who saw this pretreatment representation may think the lignin is fragmented and cellulose Cristal is damaged after treatment. In reality, it is not this situation for the majority of the pretreatment technologies published so far. Even through severe pulping process, some lignin is still linked to carbohydrate and cellulose structure is still unaffected to an striking extent.

The more appropriate visual demonstration may be shown as follow, i.e. after pretreatment, the hemicellulose, some soluble lignin, and some cellulose in amorphous regions are extracted or removed, leaving the lignocellulosic matrix with somewhat alteration.

The key for the pretreatment is to open channels/pores due to the removal of these chemical components and somewhat alteration or dislocation of the cell wall structure. As a result, it allow enzymes or chemicals more easily to transport into cell structure and function. No doubt, a relatively severe treatment causes more damage to the cell wall structure. The question is how much more degradation occurs for removed hemicellulose and cellulose (monomer sugars).

To meet the above three requirements for a pretreatment, the chemical selected should has the ability to participate and remove dissolved lignin. One of the process parameters: temperature needs to be set carefully to avoid lignin redistribution and re-deposition/re-adsorption; Because the monomer sugar formation and degradation occur simultaneously, an appropriate process configuration and operation need to be balanced to avoid more sugar degradation.

Friday, November 7, 2008

Xylose to Acetic Acid?

In hardwood, there are about 7 acetyl groups per 10 xylose units, which can be easily cleaved under alkali conditions.

Instead of converting xylose to ethanol by direct fermentation, it may make acetic acid via fermentation of xylose to acetic acid.


Therefore, 10 moles of xylose can generate 32 moles of acetic acid because 10 moles of xylose has 7 moles of acetic acid and 10 moles of xylose can be fermented to 25 moles of acetic acid.

Y.Y. LEE reported a total 76 wt% conversion and a maximum acetate concentration of 15.2g/L (2001); Parekh and Cheryan were able to achieve final broth concentrations of 102 g/l (as HAc) with 93% conversion of the glucose feedstock using dolime (Ca(OH)2Mg(OH)2) for pH control in a fed batch fermentation with cell recycle provided by cross-flow membrane filtration.

Wednesday, November 5, 2008

What can we expect from yeast for bioethanol commercial production?

For biofuel production from biomass, we want to robust microorganisms. Yeast is a traditional one but we need a yeast that has the ability to ferment both C5 and C6 sugar and more product tolerance.

Many scientists cross the world have been taking efforts to engineer yeast that can improve the speed and efficiency of ethanol production, which is a critical component to economically making biofuels a significant part of energy supply.

The 1st aspect is to engineer the yeast to ferment both C6 and C5 sugars by genetic modification. One of the example is the "Purdue yeast" developed by Nancy Ho.
The 2nd aspect is to engineer the yeast that has high-ethanol-tolerance. The typical example is the one developed by by MIT scientists (see

New direction for biofuels?

Obama's victory means the beginning of the change in the Unite State of America, a new direction to overcome the challenge and realize the dream of prosperous. What about biofuel?

Please read the news "Ethanol and Obama":

Tuesday, November 4, 2008

Is it also the time to vote for bioenergy?

US presidential election is underway today. Who will get the the job of US president?

Both candidates emphasize on alternative energy. But one of them put more emphasis on bioenergy, the other more on nuclear power energy. The fate of bioenergy in the near may be decided today.

Monday, November 3, 2008

Process configuration for saccharification using enzyme

Process configuration
separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF)

  • Run each step under optimal conditions
  • Enzymatic hydrolysis at 45-50 0C and fermentation at about 30 0C
  • Possible to run fermentation in continuous model with cell recycling

The sugar released (glucose and cellobiose) inhibit the enzyme during hydrolysis

Advantages: Glucose produced consumed immediately by fermenting microorganisms
n avoid end-product inhibition of b-glucosidase

  • Low enzyme loading
  • Fast rate of hydrolysis
  • High production rate
  • Process integration in one reactor: cost saving


  • Inability to recycle and reuse the yeast due to its mix with lignin residue
  • Formation of lactic acid
  • The difference in optimal temperature for hydrolysis and fermentation
    -A compromise but improvement by the thermotolerant yeast

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