Biobased Industrial Products Priorities for Research and Commercialization (2000) / Chapter Skim
Currently Skimming:
4 Processing Technologies
4 Processing Technologies
Pages 74-102
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 74... ...
The industries for producing chemicals and fuels from petroleum are characterized by high raw material costs relative to processing costs, while in the analogous biobased industries processing costs dominate. Reducing the costs of producing commodity biobased industrial products such as chemical intermediates derived from fermentation will depend most strongly on reducing the costs of processing technology, the focus of this chapter.
|
From page 75... ...
Prototypes Prototypes of highly integrated biorefineries already exist in the United States. Plants that currently process agricultural and forestry materials into value-added products include corn wet and dry milling plants, soybean processing plants, wheat mills, and paper mills.
|
From page 76... ...
corn wet milling industry are fuel alcohol (31 percent) , high-fructose corn syrup (36 percent)
|
From page 77... ...
However, these wastes also represent potential fermentation feedstocks for generating additional value-added products. Corn wet mills could comprise the front end of an industrial complex that produces food, specialty chemicals, industrial products, fuels, and pharmaceuticals.
|
From page 78... ...
681 Total industrial and food uses 1,655 Total corn grain produced 9,265b a Industrial uses of corn grain as raw material in the manufacturing of industrial products include industrial starch, manufacturing alcohol, and fuel alcohol. Food uses include grain processed for edible applications including high-fructose corn syrup, glucose and dextrose, cereals, food starch, and beverage alcohol.
|
From page 79... ...
Moreover, all of the wastes from soy processing plants are relatively benign biological materials that can be readily degraded in conventional waste treatment plants and are usually processed onsite. As with corn wet milling, soy processing plants could serve as the front end of an industrial complex that produces food, specialty chemicals, fuels, and pharmaceuticals.
|
From page 80... ...
and foreign refineries Impact on other users Gives fuels, food, Status quo pharmaceuticals, specialty and commodity chemicals producers more options at potentially lower costs Technical stage Early, room for Mature, not much room tremendous for improvement improvement National security Less dependence on Greater dependence on foreign feedstocks foreign feedstocks Export potential Potential to export more Increases import of finished goods from primary and finished domestic resources goods Environmental effects Largely positive to Many negatives neutral xx Lessons from Petroleum Refinery Experience Several lessons from fossil feedstock refineries might prove helpful in the future development of biorefineries and should be incorporated into strategic planning for the industry. These lessons include the following: • refineries invariably produce more and more products from the same feedstock over time, thereby diversifying outputs; • refineries are flexible and can shift outputs in response to change • processes in refineries improve incrementally over time; and • process improvement invariably makes the cost of raw material the dominant factor in overall system economics.
|
From page 81... ...
Conversion of raw materials -- such as wood, other lignocellulosic biomass, vegetable crops, starch-producing crops, and oil seeds -- to final end products often will require a combination of processes. This section identifies the technologies that might be used by future biobased industries.
|
From page 82... ...
Chemical wood pulping produces as a byproduct more than 50 million metric tons of lignin a year in the United States. The most common process in the United States for removing lignin is kraft pulping, which involves cooking wood chips with a mixture of sodium hydroxide and sodium sulfide to partially depolymerize and solubilize the lignin.
|
From page 83... ...
Potential Lignin is an important coproduct with sugars resulting from the hydrolysis of lignocellulosics. The overall economics of biorefineries that use lignocellulosics as raw materials would be improved by finding uses for lignin and avoiding lignin disposal costs.
|
From page 84... ...
The AFEX process followed by treatment with cellulases and hemicellulases gives high sugar yields (approximately 90 percent of theoretical estimates) from various raw materials using low enzyme levels (about 5 IU per gram of dry biomass; Holtzapple et al., 1991; de la Rosa et al., 1994)
|
From page 85... ...
It does not cover pulping technologies because pulp cost is generally too high for most uses in biobased products. Proven Direct combustion of wood for cooking and heating has been practiced for centuries.
|
From page 86... ...
, gases, and char. Major product yields following liquid pyrolysis can vary from 25 to 70 percent of inlet raw materials.
|
From page 87... ...
. Only limited commercial development of gasification using renewable raw materials, such as wood, to produce useful products has occurred, mainly because of the poor economics.
|
From page 88... ...
Biological Processes Biological processes often play a role in the pretreatment and conversion of renewable resources into industrial products. For example, starch resulting from corn wet milling is enzymatically hydrolyzed to glucose syrup that is then fermented to ethanol and other products.
|
From page 89... ...
. Fuel ethanol production involves fermentation of glucose syrup by the yeast Saccharomyces cerevisiae in large-scale, high-capacity fermentors.
|
From page 90... ...
The Japanese fermentation industry has dominated worldwide production of amino acids for the past 20 years and during this period has used random mutation and selection programs to develop high-producing microbe strains for many amino acids (e.g., glutamic acid, phenylalanine and lysine)
|
From page 91... ...
Their eventual dominance of the amino acid industry included numerous amino acids other than glutamic acid, such as lysine, tryptophan, phenylalanine, threonine, and aspartic acid for human nutrition and animal feeds. The last of the early U.S.
|
From page 92... ...
The production of L-malic acid, an acidulant used in beverages, involves conversion of fumaric acid by fumarase. A number of different L-amino acids used in food and feed supplements are produced enzymatically.
|
From page 93... ...
Its discovery eventu ally led to growth of the high-fructose corn syrup industry, which uses abundant corn starch from the U.S. agricultural sector as its starting raw material.
|
From page 94... ...
reactors, can produce ethanol from mixed waste papers, agricultural wastes, and pulp and paper mill wastes (Emert and Katzen, 1980, Katzen and Fowler, 1994)
|
From page 95... ...
Upstream Processes Renewable natural resources, including lignocellulosic biomass, will provide the raw materials for future biobased industries. Developing economical processes for pretreating this biomass will be essential to make
|
From page 96... ...
• improving bioreactors for heat, momentum, and mass transfer for viscous, non-Newtonian fermentation broths and solid-liquid broths; • developing new methods for monitoring biological processes, such as discrete sensors using microfabrication, real-time monitoring, and digital imaging of bioreactors; and • developing new concepts in process control, such as the applica tion of expert systems, artificial intelligence, neural networks, and principal component analysis. The development and improvement of biological conversion processes will depend on continuing research to elucidate fundamental biological principles, combined with engineering analyses to improve biobased product yield (raw material conversion)
|
From page 97... ...
to reduce production of undesirable byproducts; and • analysis of processes or steps in biochemical pathways that limit formation of desired products and identification of genetic changes to alleviate these limitations. Microbiological Systems Microbiological systems, particularly those involving anaerobic bacteria, are essentially multicatalytic reactors that direct the microbial metabolism toward the production of useful biobased products.
|
From page 98... ...
Such under standing will aid in engineering bioreactor control to enhance the rate and conversion of raw materials into useful products. • Basic research on cultures containing multiple microorganisms, particularly those in which the microorganisms have symbiotic relationships that increase growth and product formation.
|
From page 99... ...
This initial step in reversing enzyme activity gives hope that it can be done with other enzymes, but extensive fundamental research to elucidate the precise structure and mechanism of the catalytic sites of the enzymes in question must precede such work. To capitalize on and expand recent developments in enzyme processing, future research in this area should: • further explore catalysis by enzymes from thermophiles and other extremophiles; • elucidate the mechanisms that allow enzymes isolated from ex tremophiles to remain stable in hostile environments (such mecha nisms might eventually be incorporated into stabilization strategies for industrial enzymes from nonextremophiles)
|
From page 100... ...
In the production of organic solvents, this low product concentration reflects the microbe's low tolerance for these solvents. For organic acids the protonated species of the acids adversely affect the biosynthetic enzymes; neutralization of the acid is often required during fermentation.
|
From page 101... ...
Biorefineries offer a number of potential advantages over petroleum refineries, including domestic raw materials, lower environmental impacts, and potentially greater sustainability. Thermal, mechanical, chemical, and biological processes all play a
|
From page 102... ...
Further reductions in the price of the biobased raw materials will help process economics but not as much as will reducing the costs of processing technologies. Very low-cost processing technologies must be developed if biobased industrial products are to penetrate commodity markets.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.