Chapter 12 Large-scale and Industrial Utilisation - Anamed

Chapter 12
Large-scale and Industrial Utilisation
The scope for large-scale utilisation of water hyacinth is limited because of the
transport costs. Water hyacinth, being 95% water, is very heavy and bulky to
transport. Any larger-scale application must, therefore, be situated close to
where water hyacinth grows. Nonetheless, because of its abundance and
cheapness, there exists the challenge to discover means whereby valuable
products can be made, or whereby water hyacinth could be a substitute for more
expensive raw materials such as oil.
In this context, proposals have been made in both India and Bangladesh to
locate low cost, simple processing units for the manufacture of paper and board
close to areas of infestation with water hyacinth.
12.1 Building Boards
The Housing and Building Research Institute in Dhaka have experimented with
making hardboards of different densities by mixing water hyacinth board
cuttings with different kinds of adhesives including urea formaldehyde,
polyvinyl acetate and starch. They suggest that such hard boards should be
suitable for internal uses such as partition walls and false ceilings. They have
also investigated not only water hyacinth fibre reinforced cement corrugated
roofing sheets, but also roofing sheets made from bitumen coated water
hyacinth board. Such boards are light and waterproof, is effective and durable
as compared with traditional thatched roofing, and is considerably less costly
than galvanised corrugated iron sheets, see Haider (1989)
The production of water
hyacinth cement boards has
been investigated also by the
Paper and Board Division of
the Regional Research
Laboratory in Jorhat, India,
see Ghosh et al (1984). They
crushed and squeezed water
hyacinth stalks in a crusher,
and then pulped them. The
pulp was bleached by two
stage hypochlorite bleaching
with
a mild alkali extraction. It was
Figure 12.1 A fragment from a pressed
board made in the Sudan
discovered that the maximum physical strength was given by mixing 7.5 parts
water hyacinth pulp with 46.25 parts cement and 46.25 parts silica, which can be
Chapter 12 Large Scale and Industrial Utilisation Page 78

obtained from sand from fresh-water lakes. The sheets were made in a hydraulic
press, and corrugated sheets by keeping the plain sheets over a caul plate under
pressure in a hydraulic press.
Water hyacinth fibre has qualities similar to asbestos fibre; both are polymeric
and fibrous. The difference of course is that water hyacinth fibres are
combustible, but within a cement board that is of no consequence.
12.2 Greaseproof paper
Water hyacinth has also been proposed as a potential source of raw material for
greaseproof paper, see Goswami and Saika (1994). Water hyacinth is rich in
hemicellulose, which imparts greaseproofness to paper provided the fibres are
properly hydrated in a beating process rather than cut. To obtain greaseproof
qualities in bamboo or wood pulp, the pulp has to be beaten for a very long time.
In tests at the Regional Research Laboratories at Jorhat, India, water hyacinth
stalks were washed and crushed in a three roll crusher to reduce the water
content from 95% to 30-35% without damaging the fibres. The crushed stalks
were then air dried down to a water content of 15% before use. Water hyacinth
pulp blended with bamboo pulp in the ratio 3:1 was found to give optimum
qualities of strength (from bamboo) and greaseproofness (from water hyacinth).
12.3 Cardboard
The Centre for Research of Human Resources and the Environment at the
University of Indonesia, Jakarta established a factory as a model for the
production of cardboard from water hyacinth, see Roekmijati et al (1987). This
was part of their programme of seeking productive outlets for waste materials.
800kg water hyacinth and 500kg waste cardboard and paper are used each day
to produce 800kg or 4000 sheets of cardboard. Rice husks were used as the fuel
in the digestion process. The quality of the cardboard was judged not to be
particularly high, but suitable for thread cones in a thread or textile factory, for
the inner parts of hats, bags, office folders etc. Without subsidies, the process
was considered to be only just economically viable, but of significant social and
environmental usefulness,.
Workers at the Regional Research Laboratories at Bhopal, India, have
suggested that there is scope for using water hyacinth fibre in developing
composites with plastics, cement and other matrix materials, so as to be able to
make items such as fibre filled ropes, wall covers, partitions etc.
12.4 Fuel
Biomass is already a very important source of energy in many tropical countries.
In the Association of South East Asia Nations (ASEAN), it was estimated in
1997 that energy from biomass such as wood and agricultural residues
Chapter 12 Large Scale and Industrial Utilisation Page 79

epresented about 40% of total energy consumption, i.e. more than 2.5 million
Terajoules per year, see F.A.O. (1977). The bulk is in woodfuels. The main
applications are in the domestic sector and small-scale industries, but
increasingly in modern systems for combined heat and power generation.
The advantages of wood and biomass are that they are
• cheap
• locally available
• in abundant supply, and
• can save a substantial amount of foreign exchange.
In environmental terms, biomass as a source of fuel is "carbon-neutral", that
means that the CO2 released by its burning is matched by the amount used up in
its production. With modern improvements in technologies, emissions such as
carbon monoxide, polycyclo-aromoatic-hydrocarbons, nitrous oxides and
particulate matter can be drastically reduced. It is estimated that producing
energy from biomass creates 20 times more local employment opportunities than
energy production from imported sources - yet another considerable benefit.
Modern applications have demonstrated that biomass energy can be
competitive for larger-scale industrial applications.
Intermediate Technology Publications have produced an excellent guide to
the production of energy from renewable sources, see Clancy and Brandt (1994).
12.4.1 Briquettes
Briquettes are a good commercial product, because they are compact and can be
easily transported. Also, they require a large weight of water hyacinth, which
clearly makes a useful contribution to its control. It has been calculated that, to
make 40 tonnes per day of briquettes, 1,300 wet tonnes per day of water
hyacinth are required, and that an area of land of about 12 hectares are required
for sun drying, see Köser et al (1983).
Machinery is required to
• disintegrate the dried water hyacinth.
• screen it.
Figure 12.2 Screw Extrusion Press
• chop or grind it to a
6mm particle size.
• compress it into
briquettes, a pellet
mill or a ram
extrusion press.
In Thailand, a mixture of
50% water hyacinth and
50% rice husks is used,
as this gives a stronger,
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less brittle product than with water hyacinth alone, see Shah and Bhattacharya
(1983). The briquetting takes place because the compression of the screw
together with the heating coils raise the temperature to 250 degrees centigrade. It
is believed that the high temperature softens the lignin, which behaves as a
waterproof glue. They use an extruding machine that produces 2 briquettes per
minute, each 50cm long and 0.5kg in weight. The heat content of the briquettes
is about 85% that of wood charcoal The energy output of each briquette exceeds
the energy used in its production by a
factor of about ten.
In Thailand also briquettes
are made which are a mixture of
ground lignite, dried water
hyacinth and binder in the ratio
6:3:1. The binder is 4% glue,
3% resin and 3% a synthetic
compound made from tapioca.
Such briquettes, which are very
strong, have four times more
heat than wood charcoal and
cost 30% less than wood
charcoal.
In Kenya, briquettes are
produced from coffee husks. It
is possible that such briquettes
could be produced in all coffee
Figure 12.3 Piston Press
producing countries, and that water hyacinth could be combined with coffee
husks.
Depending on the particular briquetting machine used, to work effectively
they require a feedstock that
- has a moisture content of less than 18% (some require between 4 and
8%).
- consists of pieces of between 2 and 20 mm in size, and can include
some dust.
- is free of such materials as sand, earth, stones and metal.
The optimum particle size and moisture content, and the latitude, must be
determined through experience.
Briquetting machines can usually handle between 150 and 550 kg per hour,
but the Danish firm below manufacture a machine that handles 1300 kg/hr. As a
guide, a machine that produces 250kg of bricks per hour will, in a 40 hour week,
produce 5 tons of briquettes, and in a 50 week year will produce 250 tons of
briquettes.
The additional equipment required includes a hammar mill, inclusive of filter
and cyclone, drying equipment, conveyors and screw feeds, storage bins (wet
and dry), bagging equipment, exhaust fans, an electrical control panel, cutting
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equipment for the extruded material and 3 phase electrical facilities of about
150kw.
J K Köser et al (1983) suggest that air drying of water hyacinth is essential,
because water removal by mechanical means, i.e. double roll and screw
pressing, reduces the water content only to 60%. It is possible that the 12
hectares suggested above could be considerably reduced using air drying devices
described in Chapter 13, though then the mechanical equipment of tractors and
six-ton spreaders would need to be replaced with human labour.
Köser et al suggest also that the resultant briquettes have a substantially
improved calorific value, if as much as possible of the "external ash" that is a
part of water hyacinth can be removed (see Chapter 5). This can be done by
disintegrating the water hyacinth with a tape grinder, which reduces the external
minerals to particle sizes of below 3mm, whereas the plant material mostly has a
granular size of between 5 and 10mm. A gyrating screen can separate such
material into a discard fraction of less than 3mm with an ash content of 60%,
and a plant fraction containing only 12% ash. The discards are valuable as a soil
improver.
Sun /
air
drying
g
Grinder
Screen
For soil improvement
Grinder
Figure 12.4 Simplified flow-chart of the briquetting plant proposed by
Köser et al (1983).
The following are some suppliers of briquetting machines in Europe:
ABC Hansen A/S, Kirkegade 1, P O Box 73, DK 8900 Randers, Denmark
Tel: +45 86 42 64 88, Fax: +45 86 41 36 22
SHIMADA (UK), Pyrford, Wappenham, Northants, NN12 8SG, England
Tel: +44 1327 860281, Fax: +44 1327 860596
Adelmann AG, Postfach 11 50, 97747 Karlstadt, Germany
Tel: +49 9353 79030, Fax: +49 9353 790317
Hopper
Briquetting
Machine
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12.4.2 Biogas
Anaerobic digesters of all sizes, fed with a wide variety of organic raw
materials, have been built in almost every country of the world. The following
three examples were taken from the internet.
1. Denmark
A combined heat and power plant in Dalmose, which uses both natural gas and
biogas, provides 400 households in the urban districts of Dalmose and
Flakkebjerg with electricity and heating. The biogas is supplied by the Hashøj
Biogas Plant which has been established as an independent cooperative society
composed of 19 local farmers, who also supply livestock manure to the plant.
Since the summer of 1994, the combined heat and power plant has been in
full operation using biogas and natural gas as two equal fuels, each covering
50% of the fuel requirement of the two gas-driven motor generator units. The
annual combined heat and power production adds up to 8,500 MWh power,
which is supplied to the power grid, and 14,000 MWh district heating.
2. Sweden
The biogas plant is the first large plant for treatment of livestock manure and
industrial waste in Sweden. The Laholm Municipality in Halland is located in an
area with a large concentration of livestock, where investments in the
environment, decentralised energy production and secondary agricultural
produce go hand in hand. The biogas plant is an important element in this plan
with a view to increasing the use of biofuels in decentralised combined heat and
power stations.
The biogas generated meets the major part of the local heat requirements in a
new residential area comprising 350 dwellings. At the same time, electricity is
produced which is sold to the public grid.
Furthermore, livestock manure originating from 20 animal husbandry units
and organic waste from a number of local companies are converted to an
environmentally friendly fertiliser. Pasteurisation is undertaken to ensure 100%
hygienisation, so that the plant can also receive sorted household waste and
wastewater sludge.
Current research being conducted in Sweden in atmospheric pressure
gasification technology is expected to enable the production of twice as much
electrical power from biofuel as a conventional combined heat and power plant.
3. Nepal. This example is interesting, because it describes the relationship
between the construction company, the bank and the customer.
Since its establishment, the Biogas and Agricultural Equipment Development
Company has installed more than 13,000 thousand biogas plants in Nepal. Most
of them are the fixed-dome design biogas plants. The Biogas Company, with the
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joint cooperation of the Agricutural Development Bank of Nepal (ADB/N),
handles biogas promotion and development. ADB/N handles credit and
government subsidies. The company conducts a survey, studies the technical
feasibility and receives the order for the construction of a biogas plant either
through ADB/N, or from individual customers who do not want to receive credit
for biogas installation. The construction and supervision of biogas plants are
carried by a supervisor from the company. Final supervision is also done from
ADB/N branch offices. Upon completion of the biogas plant, a final bill of
payment is made to the company from the branch of the bank. To ensure the
effective utilisation of biogas plants, the Biogas Company provides a 6-year
guarantee for its operation with an annual check. If complaints come from the
customer, as many visits as are necessary are made until the problems are
resolved. Such effective services have led to a high level of operation of biogas
plants in this region. Between four and five thousand biogas plants are built each
year in Nepal.
Given a throughput of at least 100 wet tonnes per day, the most economically
promising applications for the biogas are for engine fuel or electricity
generation. The most efficient digesters may use the juice only from water
hyacinth leaves and stems, see Mbendo and Thomas (1998).
12.4.3 Other Forms of Fuel
Ethanol is manufactured in very large quantities from biomass in many
countries, including Brazil, Kenya, Malawi and Zimbabwe, for use as fuel,
including as a major supplement to petrol for motor cars. Clancy and Brandt
(1994) advise caution before constructing a large plant (see page 198), but point
out that many farmers in the USA produce fermentation ethanol, and are selfsufficient
in fuel.
Water hyacinth is certainly a suitable raw material for the processes of
fermentation and distillation from which ethanol is manufactured. Methanol can
be produced from the catalytic conversion of water hyacinth biogas. Like
ethanol, methanol can be used as an addition to petrol for cars and for industrial
purposes.
2,3-butanediol can be manufactured by the delignification of sun-dried and
crushed water hyacinth with caustic soda, the enzymatic hydrolysis of that
delignified water hyacinth and subsequent fermentation, according to
researchers at Nagpur University, India, see Motwani et al (1993). The authors
state that 2,3-butanediol is an interesting product owing to its diverse potential
uses as a polymeric substance. It has a high octane number and can therefore be
used as an octane booster for gasoline or as high-grade aviation fuel.
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Diesel fuel can be manufactured from biomass also, see Kuester (1984). In
South Africa, liquid hydrocarbon fuels have been manufactured from a nonpetroleum
feedstock, coal, for many years. In many respects, biomass has more
attractive characteristics than coal, it has more volatile matter, a higher hydrogen
to carbon ratio and lower sulphur and ash content. Its relative disadvantage is
that is has a lower heating value, because it has a higher oxygen content. Also,
of course, coal is already densified, and therefore has economies of scale,
particularly with regard to transport. But water hyacinth is plentiful and free!
Kuester, a professor of chemical engineering in Arizona, USA, believes that
270 litres of diesel type fuel can be produced from one ton of feedstock on a dry,
ash-free basis. The chemical process involves firstly the production of a
synthesis gas containing olefins, hydrogen and carbon monoxide using a
circulating solid fluidised bed gasification system, followed by catalytic
liquefaction in which the synthesis gas is converted into liquid hydrocarbon fuel.
Pyrolysis may produce not only a combustible gas, but also liquid compounds
and a solid residue which performs well as an alternative to charcoal,
according to research undertaken at the University of Hohenheim in Germany.
The results presented in Figure 12.5 were obtained with pyrolysis of dried water
hyacinth at a range of temperatures. The chart shows how the proportion of the
solid residue, a product which could be a substitute for charcoal, decreases with
an increase in processing temperature, whereas the gas fraction increases, see
Philipp et al (1979).
Figure 12.5 Pyrolysis of Water Hyacinth
(fractions in % by weight)
solid residue
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12.5 Carbon Black
Carbon black is produced from the pyrolysis of water hyacinth at 350°C, see
Sumathi et al (1984) and Ahmed et al (1984). This can be used as a black
pigment in paints and inks, in carbon paper, the tyre and tube industry, the
rubber industry and in plastics. In the investigation of Sumathi et al, the dried
stalks of leaves were carbonised in an open stainless steel vessel for 10 minutes,
and the resulting carbon was ground into a fine powder. Addition of this carbon
black to water hyacinth pulp together with normal sizing agents such as rosin
soap and alum gave only light grey coloured papers. In Ahmed et al, dried water
hyacinth stems were carbonised for 20 minutes, finely powdered, impregnated
with ZnCl2 and activated with superheated steam. They suggest that this process
is potentially economic, if the ZnCl2 can be recycled, and that the product can
be used safely in the medicinal and pharmaceutical industries.
12.6 Water hyacinth in water purification
Water hyacinth has been shown to be effective in removing a vast range of
impurities from water, amongst them the following:
• Metals; copper, zinc, iron, mercury, cromium, calcium
• Sewage effluents
• Livestock manure and runoff from agricultural land
• By-products of sugar refining, tanneries, palm oil manufacture, cheese
making, rubber factories
• Algae, suspended matter and odour causing compounds.
• Bacteria, fungi and viral substances
• Acids, alkalis and salts
• Organic compounds, including phenols
• Toxic substances such as pesticides
Scientists have suggested that impurities are taken up by the water hyacinth
by means of:
processes of diffusion and osmosis through the outer surfaces of the root
hairs and
processes of ion exchange of metal ions and ions of chemicals at the root
surfaces. Both fresh and dried water hyacinth function as ion exchangers in
the presence of metal ions.
Water hyacinth thrives where there are high levels of nutrients, and this very
quality can be used to advantage. The majority of contaminants are converted by
the water hyacinth into harmless waste, and so the used plants can be safely
composted or used as mulch.
Under ideal conditions, one hectare of water hyacinth plants can absorb the
average daily nitrogen and phosphorus waste production of over 800 people.
The water hyacinth should cover not more than one third of the water surface.
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The use of aquatic plants for purifying effluent water has achieved great
popularity in recent years. Paradoxically, it is possible that if water hyacinth
were to be used by local authorities and industries for cleaning up their wastes,
given efficient filtering at the purified water outlet to collect broken off plant
parts and seeds, the conditions for water hyacinth growth downstream would be
considerably less ideal.
12.7 Possibilities for the use of water hyacinth in food and pharmaceuticals
12.7.1 Microcrystalline cellulose (MCC)
MCC produced from water hyacinth was found to be comparable with
commercial MCC in almost all respects, in tests made at the food and
Fermentation Technology Division of the Department of Chemical Technology
at the University of Bombay, see Gaonkar and Kulkarni (1987). It was tested
with good results as a thickening agent with mango juice and as an anti-caking
agent for powdered sugar.
12.7.2 Cellulase
The National Environmental Engineering Research Institute in India has
undertaken a cost-benefit analysis for the production of cellulase from water
hyacinth, which is to be harvested from Akkulam Lake in Kerala, a major tourist
attraction near Thiruvananthapuram. The plant will process 4,000 kg/day
harvested water hyacinth to produce 400,000 IU cellulase enzyme and 180kg
compost. The investment payback period was estimated as 4.5 years, with 50%
of the capital cost as grant-in-aid from the Ministry of Environment and Forests,
Government of India. The cost benefit analysis considered both the direct
(cellulase and compost) as well as the indirect (recreational, health, navigational
and fisheries) benefits, see Khanna 1998.
12.7.3 Possibilities with pharmaceuticals
It has been claimed that protein and amino acid concentrates extracted from
water hyacinth leaves contain vitamin A, which could be isolated. The roots and
rhizomes yield stigmasterol which is used in some synthetic steroidal drugs. It
has been reported also that the roots contain diosgenin, used in the synthesis of
first progesterone and then cortisone. Homeopathic medicines have also been
made from water hyacinth, see Haider (undated). We are not aware, however, of
any recent publications on this subject, nor of any project that produces
pharmaceuticals.
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12.8 Production of fertilisers
As mentioned already in paragraph 3.6, Bio-Earth (Uganda) Ltd. produce
organic fertilisers in substantial quantities. They use the following process;
Stage 1. Water hyacinth is brought in by truck.
Stage 2. The entire plant is crushed in a hammer mill together with coffee
husks, so that the resultant mixture has a moisture content of 55%
Stage 3. Rock phosphate and/or ash is added in such proportions as to give
the desired nitrogen, phosphorus and potassium contents and ratios.
Stage 4. The entire mixture is placed in a container with a blower system to
introduce air - for 10 days. A temperature of 65 - 70°C is achieved,
and weed seeds and pathogens are killed. The process is complete
when the temperature drops, and the oxygen content falls below
14.4%
Stage 5 The mixture is then placed in windrows for 6 weeks, and stirred
once a week. The process is finished when the temperature drops
below 40°C.
Stage 6. The product is screened to remove large particles, and bagged for
distribution and sale.
In stage 3, phosphate and ash are added in varying proportions to produce
different fertilisers for bananas, tea, coffee and vegetables, sugar cane, and they
also produce a universal fertiliser.
This project has been financed by aid from Denmark. They receive technical
support from Makerere University, from which they are also provided with
facilities for analysis of soil and fertiliser contents. The project workers hope
that the enterprise will become self standing, and have ambitious plans to
produce 6,000 tons of fertiliser per year. The most expensive steps are the
harvesting and transport of the fresh water hyacinth.
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