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1. Introduction:
Modern biotechnology is a powerful and versatile tool which can compete
with chemical and physical means of reducing energy and material consumption
and minimising the generation of waste and emissions.
There is general agreement that the use of biotechnology in industry does
not simply remove pollutants but also will prevent pollution at the
source.
Efforts to achieve clean industrial products and processes will also bring
great benefits to industry over the next ten or twenty years.
Industrial biotechnology, using microorganisms and biological catalysts
(enzymes) to produce goods and services, has come of age.
Biotechnology and CO2 emissions
The soya bean: an important renewable resource
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The soya bean has long been used to develop products ranging from
foiod and diesel fuels to polymers, fabric softeners, solvents, adhesives,
linoleum, rubber substitutes, printing inks, and plastics. Recent
advances in recombinant genetic biotechnology have made it possible
to alter the lipid composition of soya beans to increase the variety
of biohydrocarbons available for industrial applications. Amides,
esters and acetates of biohydrocarbons are currently used as plasticisers,
blocking/slip agents and mold-release agents for synthetic polymers.
Biohydrocarbons linked to amines, alcohols, phosphates and sulfur
groups are used as fabric softeners, surfactants, emulsifiers, corrosion
inhibitors, anti-static agents, hair conditioners, ink carriers, biodegradable
solvents, cosmetic bases and perfumes. In combination with aluminium
and magnesium, the soya bean is used to produce greases and marine
lubricating materials. |
2. Biotechnology in industrial sectors
Various parts of the industry are experimenting with the new tools offered
by biotechnology. Of particular interest is the possibility of using biobased
resources as feedstocks in the larger volume sectors. While biobased manufacturing
will not necessarily always be cleaner, it is certain that wastes from
biobased manufacturing will be more compatible with conventional wastewater
treatment systems.
Pharmaceuticals
Today, many pharmaceuticals are semi-synthetic molecules, in that part
of their structure is synthesised by a living organism and later modified
by chemical processing. Thanks to biocatalysis optimised fermentation,
and replacement of organic solvents by water, modern biotechnology contributes
to cleaner production of such semi-synthetic antibiotics.
An enzymatic process for producing an antibiotic
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Thermostabilised enzymes and the development of a new bioreactor
process by Kaneka Corporation are used to produce 2,000 metric tons
a year of amoxicillin, an antibiotic. This all-enzymatic process has
displaced an older one in which part of the synthesis was carried
out chemically but created problems, including coloring of the product,
formation of by-products, and low energy efficiency. |
Textiles and leather
The textiles industry is continuously seeking new sources of innovation,
one of which is biotechnology. In 1996 the global enzyme market for textiles
amounted to $ 178 million. Moreover, textile and apparel companies are
spending more time and money on environmentally relevant issues. Regulatory
pressure is expected to intensify for both textiles and leather as less
polluting technologies become available and it becomes possible to generate
less waste.
Enzymes have been used in textile processing since the early part of this
century to remove starch-based sizing, but only in the past decade has
serious attention been given to using enzymes for a wide range of textile
applications.
Enzymes are expected to have an even greater impact on effluent quality
as more fibre preparation, pre-treatment and value-added finishing processes
convert to biotreatment. In addition, enzymes are very effective catalysts
even under mild conditions and do not require the high energy input often
associated with chemical processes.
Food:
In the food sector, biotechnology has long played an accepted role in
traditional processes, such as cheese making. Both modern and traditional
biotechnology can be an important supportive tool for the food industry
and give considerable added value to food products. When evaluating the
use of biotechnology "from the farm to the fork" it is necessary to balance
the environmental impact of commercial agriculture with that of alternative
production routes, such as growth of microorganisms in fermentors or from
fossil fuel feed stocks. The environmental benefits of producing food
additives by fermentation or enzymatic routes instead of traditional organic
synthesis are similar to those for other specialty chemicals. In the case
of fermentation-derived preservatives, the effect is even more favorable
when the fermentation broth is incorporated in the finished product. In
the most desirable situation, bacteriocin-producing cultures are used
in fermented foods (such as sauerkraut) where they consume carbohydrates,
naturally preserve the finished product and contribute nutritive value
of their own. A biotechnology application with very great potential environmental
benefit would convert waste streams from one process into raw materials
for another, or upgrade underutilised raw materials into a more valuable
form.
Ideas abound, including alternative uses for the grape pomace left over
from wine-making, corn cobs as a substrate for citric acid production,
and cranberry waste as a substrate for fungal bioinoculants. Use of the
large quantities of whey produced during cheese making also hold out great
promise. One successful approach has been the production of lactose-fermenting
yeasts as flavoring ingredients.
Sugars from starches
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Starch processing involves the conversion of maize or another grain
into dextrose and other syrups by a hydrolysis reaction. This was
formerly done using acid at high temperature and pressure, but dextrose
yields were limited to about 80 %, the process was hazardous and expensive
and produced large quantities of salt as a by-product. The initial
change to enzymatic hydrolysis in the 1960s increased dextrose yields
and eliminated the drawbacks of the acid process. In the 1970s, development
of immobilised glucose isomerase enzymes enabled the production of
high fructose corn syrup. In the 1980s, thermostable alpha-amylases
helped increase yields, and in the 1990s, recombinant thermostable
amylases have helped reduce costs. |
Animal feed
Since the common protein sources used in animal feeds (e.g. soya, fishmeal,
wheat and maize ) are deficient in methionine, lysine, threonine and tryptophan,
these essential amino acids are added as supplements to monogastric diets,
e.g. for poultry and pigs. Whereas methionine is produced by chemical
synthesis (300,000 tons in 1996) lysine, threonine and tryptophan are
produced by industrial fermentation, using mutants of Corynebacterium
glutamicum and recombinant strains of E.coli.
Feed enzymes are designed to degrade components of raw materials that
limit digestibility and/or lead to higher levels of excretion of manure,
nitrogen and phosphorus. Endoxylanases and phytases are the best-known
feed-enzyme products. Endoxylanase enzymes hydrolyse phytic acid and release
inorganic phosphate, thereby avoiding the need to add inorganic phosphates
to the diet and reducing phosphorus excretion. If phytase is added to
feeds for pigs to liberate phosphate in the feed, phosphate release in
manure is reduced by 30 %. In a country like the Netherlands, this would
reduce the phosphate released into the environment by 20,000 tons a year.
The marginal price increase in the feed cost to farmers (about 2 %) would
be compensated for by a reduced levy on discharge of phosphate.
Pulp and Paper
The pulp and paper industry is very capital-intensive with small profit-margins.
It must meet increasing demand for pulp and paper and, at the same time,
comply with increasingly stringent environmental regulations. Driven by
market and environmental demands for less chlorinated products and by-products,
it is the fastest growing market for industrial enzymes. In the United
States, this market is projected to grow by 15 % a year for the next ten
years.
In paper-making, various processes are used to separate the cellulose
fibres from the lignin in wood to form a slurry (pulp) that is then processed
into paper and board. Existing chemical pulping operations create a great
deal of pollution. Biopulping, which involves the treatment of lignocellulosic
materials with lignin-degrading fungi, has been shown to result in energy
savings and strength improvements. Enzymes are now also being incorporated
into the pulping process, where they offer a number of advantages.
The structure and chemical chemical composition of pulp fibres are of
paramount importance for paper strength and other properties. Enzymes
can be used to reduce fibre coarseness, increase paper density and smoothness,
and improve appearance. Most pulp is produced using the kraft process.
Kraft pulps have a characteristic brown colour, which must be removed
by bleaching before manufacturing paper for writing or other products
for which appearance is important. Chlorination is traditionally used,
but pulp manufacturers are turning to other techniques because of consumer
resistance and environmental regulations. According to studies conducted
in Finaland, hemicellulases (mainly xylanases) improve bleaching. They
are now being used commercially in Scandinavia, Canada, the United States,
and Chile. Treating kraft pulps with xylanases significantly reduces chemical
consumption with almost no loss in pulp yiels or quality. A new enzyme
that is better suited to the temperatures and pH found in pulp processing
has also been developed in Israel and successfully tested in a large-scale
trial.
Using bacteria to remove by-products
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Adding polymers to paper stops fibres from becoming waterlogged
and gives the paper wet strength. However, the polymer production
process creates contaminants which reduce its effectiveness. Carbury
Herne Limited and Hercules Inc. have developed a bioprocess for removing
these by-products.
Two strains of bacteria are used to digest the by-products which are
then washed out of the polymer before it is applied to the paper.
This treatment is considered not only more environmentally acceptable,
but it is also less expensive than developing a new product or a new
manufacturing process to do the same job.
The process has now been adopted at production scale at two plants
that make packaging paper for food liquids. As the bioreactors were
built into existing production lines, costly redesign of the production
process was avoided. |
Energy
Biotechnology is having a major effect on the economics and the environmental
impact of the energy sector. Biotechnology can produce cleaner coal and
petroleum, chiefly by removing sulfur and thus reducing the environmental
contaminants released during combustion. Production of low-sulfur fuels
will extend fossil fuel reserves and reduce levels of air contaminants.
Biotechnology also has the potential for producing equivalents to petroleum
distillates, such as biodiesel. Ethanol, methane, and molecular hydrogen
are even cleaner fuels, all of which would, if produced biologically,
greatly lower levels of greenhouse gases.
The bioconversion of synthesis gas to liquid fuels such as methanol is
also being investigated. Synthesis gas is a mixture of CO, H2 and CO2
made by the partial oxidation of any carbon-based material. Feeds for
the production of synthesis gas include agricultural, municipal, and paper
wastes and biomass grown specifically for this purpose. The range of feeds
for synthesis gas make it a particularly versatile source of fuels. With
potentially lower processing costs and greater carbon yield, fuels derived
from synthesis gas are an attractive alternative to fuels produced by
fermenting biomass-derived sugars.
Bioethanol
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Bioethanol is a liquid transportation fuel. Currently, most bioethanol
is made from sugar cane, maize and other starch crops. In the United
States, close to a billion gallons of ethanol are produced annually,
and in Brazil production may be four times that. However, a tax credit
is needed to achieve a competitive market price. To be economically
competitive with fossil fuels, the technology for producing ethanol
from biomass-derived sugars will require using high-yield low-cost
crops and more efficient methods of converting lignocellulosic waste
material into fermentable sugars. These two areas are the focus of
current research. In studies sponsored by the Department of Energy,
US scientists are investigating a simultaneous saccharification and
fermentation procedure for converting cellulose to ethanol. The process
combines cellulose hydrolysis and fermentation steps in one vessel
to produce high yields. The objective is to develop, by the year 2000,
technologies for producing ethanol from biomass at a cost that will
be competitive, without tax incentives, with the cost of gasoline.
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Metals and minerals
There are two biotechnological processes used in the mining industry for
the recovery of metals and minerals. To date, the cleanliness of bioprocesses
compared to conventional metal recovery methods has not yet been established;
the use of life cycle assessment would be helpful.
Biotech for mining and metals recovery includes the use of microorganisms
for bioleaching and minerals bio-oxidation. These processes are employed
worldwide by the mining industry to extract base and precious metals.
They use bacteria, principally Thiobacillus ferrooxidans and Leptospirillum
ferrooxidans and certain thermophilic (high temperature) bacteria to leach
metals such as copper and gold from a sulfide mineral. Copper recovery
companies that use bioleaching report that it has advantages over conventional
roasters, smelters, and pressure autoclaves:
- no noxious gases are produced;
- construction time is shorter;
- environmental permits are acquired faster and environmental reporting
is less onerous;
- no toxic effluents are produced;
- environmentally stable iron arsenate residue is produced;
- metal recovery is excellent;
- operation is simple and safe, as processing is at ambient temperature
a nd pressure;
- smaller projects can be developed economically.
Biotechnology in the galvanising industry
Landskrona Galvanoverk in Sweden has designed a biotechnological process
for metal finishing to replace the traditional alkaline degreasing process,
which uses 5 % sodium hydroxide at pH 11-14. The enzymatic degreasing
process has replaced the alkaline process, which creates a large volume
of wastewater containing heavy metals. The new process, which is also
used in two other companies, produces half as much sludge and uses a tenth
the quantity of water. In addition, thanks to cost savings, the payback
time is expected to be five years.
Modern biotechnology offers new approaches to cleaner industrial products
and processes. At its core is the principle of working in harmony, rather
than conflict, with the natural world. Biotechnological solutions can
supplant technologies that pollute the biosphere and/or deplete finite
resources, but industry, the research community, government, and the public
need to work together to help biotechnology fulfill its potential for
industrial sustainability.
Biotechnology in the galvanising industry
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Landskrona Galvanoverk in Sweden has designed a biotechnological
process for metal finishing to replace the traditional alkaline degreasing
process, which uses 5 % sodium hydroxide at pH 11-14. The enzymatic
degreasing process has replaced the alkaline process, which creates
a large volume of wastewater containing heavy metals. The new process,
which is also used in two other companies, produces half as much sludge
and uses a tenth the quantity of water. In addition, thanks to cost
savings, the payback time is expected to be five years. |
Modern biotechnology offers new approaches to cleaner industrial
products and processes. At its core is the principle of working in harmony,
rather than conflict, with the natural world. Biotechnological solutions
can supplant technologies that pollute the biosphere and/or deplete finite
resources, but industry, the research community, government, and the public
need to work together to help biotechnology fulfill its potential for
industrial sustainability.
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