Possible utilization of the water hyacinth in nutrition and industry

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Possible utilization of the water hyacinth in nutrition and industry Powered By Docstoc
					          Ha Mai Anh
         Bo Thu Huyen

Possible utilization of the
water hyacinth in nutrition
 and industry in Vietnam

Horizon International Bilingual School
1. Target:
   Water Pollution is one of the biggest problems in the world. We
    research for the best solution for water pollution in Saigon River in
   To purify water using Water Hyacinth plant.
   To control the growth of water hyacinth
   To use it reasonably in industry

2. Method and Material
  2.1. Introduction
  2.2. Disadvantages
  2.3. Solutions
  2.4. Advantages

3. Equipment:
  3.1. Water’s Samples
  3.2. Nutrition Fact Table
  3.3. Biogas
  3.3. Water hyacinth’s furniture

4. Conclusions

5. Sources

6. Special thanks
1. Target:
      Water Pollution is one of the biggest problems in the world. We research for
       the best solution for water pollution in Saigon River in Vietnam.
      Purify water using Water Hyacinth plant.
      How to control the growth of water hyacinth.
      How to use it reasonably.

2. Method and Material:
2.1 Introduction:
                                                                     Life history:
                                                                     Why did
                                                                     botanists, and
                                                                     travelers carry
                                                                     water hyacinth to
                                                                     Vietnam between
                                                                     the 16th and the
                                                                     20th centuries?
                                                                     How did they
                                                                     carry and tend it?
                                                                     Can we go back
                                                                     the earliest dates,
                                                                     specific points of
                                                                     introduction and
                                                                     pathways of
                                                                     dispersal in
                                                                     Vietnam? These
are hard questions to answer given the dearth of evidence. However, it is worth
mentioning that several institutions were instrumental to the transfer of biota between
Vietnam and Mekong River before the 20th century.
Scientific classification
Kingdom:              Plantae
Division:             Magnoliophyta
Class:                Liliopsida
Order:                Liliales
Family:               Pontederiaceae
Genus:                Eichhornia
 Seven species, including:
 E. azurea - Anchored Water Hyacinth
 E. crassipes - Common Water Hyacinth
 E. diversifolia - Variableleaf Water Hyacinth
 E. paniculata - Brazilian Water Hyacinth

Water hyacinth is a non-native, invasive, free-floating aquatic macrophyte. With
board, think and glossy ovate leaves, water hyacinth may rise some 1 meter in height.
The leaves are 10-20 cm across, supported above the water surface by long, spongy
and bulbous stalks. The feathery, freely hanging roots are purplish black. As much as
50 percent of a single water hyacinth’s biomass can be roots, which extend to a depth
of up to 2 feet in the water. Moreover, its dramatic lavender flowers and shiny green
leaves make it highly prized as an ornamental plant. Water hyacinth is known as one
by way of runners, eventually forming daughter plants. The growing season for water
hyacinth is typically from March to early December. However, the majority of plants
do not die and carry over plants begin to grow in spring as the weather warms. Plants
can tolerate extremes of water level fluctuation and seasonal variations in flow
velocity, extremes of nutrient availability, pH, temperature and toxic substances. It
spreads and grows rapidly under favorable temperature and nutrient condition
(warmer temperatures and higher nutrient levels)
           Distribution: North region of South America, Asia , Australia and Africa

   2.2 Disadvantages:
    Hindrance to water transport: Access to harbours and docking areas can be
    seriously hindered by mats of water hyacinth. Canals and freshwater rivers can
    become impassable as they clog up with densely intertwined carpets of the weed.

   Clogging of intakes of irrigation, hydropower and water supply systems: Many large
    hydropower schemes are suffering from the effects of water hyacinth. The Owen Falls
    hydropower scheme at Jinja on Lake Victoria is a victim of the weeds rapid
    reproduction rates and an increasing amount of time and money is having to be
    invested in clearing the weed to prevent it entering the turbine and causing damage
    and power interruptions. Water hyacinth is now a major problem in some of the
    world’s major dams - the Kariba dam which straddles the Zambia-Zimbabwe border
    on the Zambezi River and feeds Harare has pronounced infestations of the weed.

   Blockage of canals and rivers causing flooding: Water hyacinth can grow so densely
    that a human being can walk on it. When it takes hold in rivers and canals it can
    become so dense that it forms a herbivorous barrage and can cause damaging and
    dangerous flooding.

   Micro-habitat for a variety of disease vectors: The diseases associated with the
    presence of aquatic weeds in tropical developing countries are among those that
    cause the major public health problems: malaria, schistosomiasis and lymphatic
    filariasis. Some species of mosquito larvae thrive on the environment created by the
    presence of aquatic weeds, while the link between schistosomiasis (bilharzia) and
    aquatic weed presence is well known. Although the statistical link is not well defined
    between the presence of aquatic weeds and malaria and schistosomiasis, it can be
    shown that the brughian type of filariasis (which is responsible for a minor share of
    lymphatic filariasis in South Asia) is entirely linked to the presence of aquatic weeds.

   Increased evapotranspiration: Various studies have been carried out to ascertain the
    relationship between aquatic plants and the rate of evapotranspiration compared with
    evaporation from an open-surfaced water body. The rate of water loss due to
    evapotranspiration can be as much as 1.8 times that of evaporation from the same
    surface but free of plants. This has great implications where water is already scarce.

   Problems related to fishing: Access to sites becomes difficult when weed infestation
    is present, loss of fishing equipment often results when nets or lines become tangled
    in the root systems of the weed. These problems make fisherman get struck up socio-
    economic problems seriously.

   Reduction of biodiversity: Where water hyacinth is prolific, other aquatic plants have
    difficulty in surviving. This causes an imbalance in the aquatic micro-ecosystem and
    often means that a range of fauna that relies on a diversity of plant life for its
    existence, will become extinct. Diversity of fish stocks is often effected with some
    benefiting and others suffering from the proliferation of water hyacinth. People often
    complain of localised water quality deterioration. This is of considerable concern
    where people come to collect water and to wash.

   In a murine ,malaria model, immunization with a tetanus toxoid- Plasmodium berghei
    peptide conjugate resulted in rates of protection ranging from 75 to 87%, identical to
    those observed with a killed vaccine made of the whole parasite

2.3 Solutions:

The 3 main mechanisms used are biological, chemical and physical control. Each ha sits
benefits and drawbacks. Chemical control is the least favored due the unknown long-term
effects on the communities with which it comes into contact. Physical control, using
mechanical mowers, dredger or manual extraction methods, is used widely but it costly
and cannot deal with very large infestations. It’s not suitable for large infestations and is
    generally regarded as a short-term control method, being relatively easy to use and
    arguably providing the only economic and sustainable control.

Chemical control:
The application of herbicides for controlling water hyacinth has been carried out for many
The common herbicides are 2,4-d, Diquat and Glysophate. It has been found that there is a
good success rate when dealing with small infestations but less success with larger areas.
Application can be from the ground or from the air and requires skilled operators. As
mentioned earlier the main concern when using herbicides is the environmental and health
related effects,especially where people collect water for drinking and washing.

Physical control:
Mechanical removal of water hyacinth is seen as the best short-term solution to the
proliferation of the plant. It is however costly, using either land-based ‘clamshell’ bucket
cranes, dragline or booms or, alternatively, water based machinery such as mowers, dredges,
barges or specially designed aquatic weed harvesters. Such methods are suitable for only
relatively small areas.
Many of these techniques require the support of a fleet of water and land-based vehicles for
transporting the large quantities of water hyacinth which is removed. Mats of water hyacinth
can be enormous and can have a density of up to 200 tonnes per acre
Manual removal of water hyacinth is suitable only for extremely small areas. It is difficult,
labour intensive work and in some areas there are serious health risks associated with the
work. Transportation of the harvested weed is also costly, because it has such a high water
content. Chopping can reduce the volume and the water content. Besides these three
mainstream forms of control Harley, Julien and Wright suggest another method, namely the
reduction of nutrient inputs to the water. Although strictly speaking this is a preventative
method, it can be argued that a reduction in nutrients in the water body will result in
a reduction in the proliferation of water hyacinth. In recent decades there has been a
significant increase in the level of nutrients dumped into waterways from industrial and
domestic sources as well as from land where fertilisers are used or where clearance has
caused an increase in runoff.

Biological control
Biological control is the use of host specific natural enemies to reduce the population density
of a pest. Several insects and fungi have been identified as control agents for water hyacinth.
These include a variety of weevils, moth and fungi. Biological control of water hyacinth is said
to be environmentally benign as the control agents tend to be self-regulating. Control
programmes are usually inexpensive due to the fact that the control agents are known and
only a small numbers of staff are required to run such programmes. One major drawback is
that it can take a long time to initiate such projects because it can take several years for the
insect population to reach a population density sufficient to tackle the pest problem.
            Supported: Australian center for international agricultural research

                     Before                               After

       The mite Orthogalumna terebrantis Wallwork
   The moth Acigona infusella Walker and Sameodes albiguttalis The miridae
    Eccritotarsus catarinensis Carvalho)
   The weevils Neochetina eichhorniae Warner and Neochetina bruchi Hustache

2.4 Advantages:
Although there are some disadvantages, we can utilize water hyacinth to make
profits for Our Country – Vietnam – such as producing paper, fiber board,

    Paper: The Mennonite Central Committee of Bangladesh has been experimenting
    with paper production from water hyacinth for some years. They have established two
    projects that make paper from water hyacinth stems. The water hyacinth fibre alone
    does not make a particularly good paper but when the fibre is blended with waste
    paper or jute the result is good. The pulp is dosed with bleaching powder, calcium
    carbonate and sodium carbonate before being heated. Similar small-scale cottage
    industry papermaking projects have been successful in a number of
    countries,including the Philippines, Indonesia, and India.

   Fibre board: Another application of water hyacinth is the production of fibreboards for
    a variety of end uses. The House and Building Research Institute in Dhaka has
    carried out experimental work on the production of fibre boards from water hyacinth
    fibre and other indigenous materials. They have developed a locally manufactured
    production plant for producing fibreboard for general-purpose use and also a
    bituminised board for use as a low cost roofing material.The chopped water hyacinth
    stalks are reduced by boiling and then washed and beaten. The pulp is bleached and
    mixed with waste paper pulp and a filter agent such as china clay and the pH is
    balanced. The boards are floated in a vat on water and then finished in a hand press
    and hung to dry. The physical properties of the board are sufficiently good for use on
    indoor partition walls and ceilings. Investigations into the use of bitumen coated
    boards for roofing are underway.

   Charcoal briquetting: This is an idea which has been proposed in Kenya to deal with
    the rapidly expanding carpets of water hyacinth which are evident on many parts of
    Lake Victoria. The proposal is to develop a suitable technology for the briquetting of
    charcoal dust from the pyrolysis of water hyacinth. The project is still very much at the
    idea stage and both a technical and a socio-economic study are planned to evaluate
    the prospects for such a project.
   Biogas production: The possibility of converting water hyacinth to biogas has been an
    area of major interest for many years. Conversion of other organic matter, usually
    animal or human waste, is a well established small and medium scale technology in a
    number of developing countries, notably in China and India. The process is one of
    anaerobic digestion which takes place in a reactor or digester (an air tight container
    usually sited below ground) and the usable product is methane gas which can be
    used as a fuel for cooking, lighting or for powering an engine to provide shaft power.
    The residue from the digestion process provides a fertiliser rich in nutrients. The use
    of water hyacinth for digestion in a traditional digester presents someproblems. Water
    hyacinth has a very high water content and therefore harvesting effort yields a low
    reward in terms of organic matter for conversion to biogas. The digester size has to
    be large compared with that of a traditional type due to the low gas production to
    plant volume ratio and this can in turn present problems for obtaining an airtight seal.
    Water hyacinth has to be pre-treated before entering the digester (macerated,
    chopped or beaten) to promote digestion and to remove air entrapped in the tissue of
    the plant which would cause it to float.

   Water purification: Water hyacinth can be used to aid the process of water
    purification either for drinking water or for liquid effluent from sewage systems. In a
    drinking water treatment plant water hyacinth have been used as part of the
    pretreatment purification step. Clean, healthy plants have been incorporated into
    water clarifiers and help with the removal of small flocs that remain after initial
    coagulation and floc removal or settling.The result is a significant decrease in turbidity
    due to the removal of flocs and also slight reduction in organic matter in the water.In
    sewage systems, the root structures of water hyacinth (and other aquatic plants)
    provide a suitable environment for aerobic bacteria to function. Aerobic bacteria feed
    on nutrients and produce inorganic compounds which in turn provide food for the
    plants. Water hyacinth has also been used for removal or deduction of nutrients,
    heavy metals, organic compounds and pathogens from water.

   Animal fodder: In Vietnam pig farmers boil chopped water hyacinth with vegetable
    waste, rice bran, copra cake and salt to make a suitable feed for pigs and ducks, also
    for fishes. The high water and mineral content mean that it is not suited to all animals.
    The use of water hyacinth for animal feed in developing countries. Animal feed is
    often in short supply and although humans cannot eat water hyacinth directly, they
    can feed it to cattle and other animals which can convert the nutrient into useful food
    products for human consumption.

   Fertilizers: Water hyacinth can be used on the land either as a green manure or as
    compost. As a green manure it can be either ploughed into the ground or used as
    mulch. The plant is ideal for composting. After removing the plant from the water it
    can be left to fry for a few days before being mixed with ash, soil and some animal
    manure. Microbial decomposition breaks down the fats, lipids, proteins, sugars and
    starches. The mixture can be left in piles to compost, the warmer climate of tropical
    countries accelerating the process and producing rich pathogen free compost which
    can be applied directly to the soil. The compost increases soil fertility and crop yield
    and generally improves the quality of the soil. Compost can be made on a large or
    small scale and in well suited to labor intensive, low capital production. In developing
    countries where mineral fertilizer is expensive, it’s an elegant solution to the problem
    of water hyacinth proliferation and also poor oil quality. In Vietnam, water is mixed
    with organic municipal waste, grass and species, also with fungi (Trichodema) and
    sold to farmers and stores.

   Furniture: Made with the water hyacinth vine wove around a wood and rattan frame,
    the furniture is very durable and easy to maintain. Water hyacinth is a easily
    replenished plant that dries to a soft and strong fiber. This furniture has been in
    production for only a few years but is getting attention from designers around the
    globe for it's unique appearance and durability.
   3. Equipment:

   3.1. Water’s samples:



We took this sample from water hyacinth's water .This is a kind of bacteria
convert ammonium to N2 which means composition of waste material into
useable form of nitrogen.

Nitrogen-fixing bacteria form symbiotic associations with the roots of legumes like
clover and lupine, and trees such as alder and locust. Visible nodules are created
where bacteria infect a growing root hair (Figure 4). The plant supplies simple carbon
compounds to the bacteria, and the bacteria convert nitrogen (N2) from air into a form
the plant host can use. When leaves or roots from the host plant decompose, soil
nitrogen increases in the surrounding area.

Nitrifying bacteria change ammonium (NH4+) to nitrite (NO2-) then to nitrate
(NO3-) – a preferred form of nitrogen for grasses and most row crops. Nitrate is
leached more easily from the soil, so some farmers use nitrification inhibitors to
reduce the activity of one type of nitrifying bacteria. Nitrifying bacteria are
suppressed in forest soils, so that most of the nitrogen remains as ammonium.

Denitrifying bacteria convert nitrate to nitrogen (N2) or nitrous oxide (N2O) gas.
Denitrifies are anaerobic, meaning they are active where oxygen is absent, such as in
saturated soils or inside soil aggregates.

   3.2 Nutrition fact table:
   According to United Nations University research, we got this information. This
   tells us how close protein we eat and water hyacinth leaves grow in human waste.

   Water hyacinths have a water content of over 90 per cent. The dry matter contains
   between 10 and 26 per cent of crude protein, but the leaves contain higher levels
   (about 38 per cent). The mineral content depends directly on the water where the
   hyacinth grows, but the mean value ranges from 17.0 to 26 per cent. The fibre
   level averages about 20 per cent. For leaf flour, for example, a net protein ratio
   (NPR) value of 3.7 was found (this is 85 per cent of that in the casein control); for
   petioles, the NPR was 1.7, but we expected this because of the high fibre content
   in this part of the plant. For the total plant, the result was poor, but this can be
   explained on the basis of its high fibre content, and principally because of the high
   mineral levels in the roots

The protein quality of water hyacinth leaves grown on human waste is presented in
table 1, in comparison with the FAO reference pattern. This table shows that water
hyacinth may be a good source of high-quality protein and other nutrients like
vitamins; however, technology for its optimum utilization must still be developed.
There are many possibilities; the most important, perhaps, is that of leaf protein
concentrate (LPC) production for use in countries with high rates of undernutrition
and malnutrition (27, 28). It is interesting to compare the geographic area where water
hyacinths grow with the hunger map of the world

TABLE 1. Comparison between the 1973 FAO Protein Reference Pattern and the
Protein of Water Hyacinth Leaves Grown in Human Wastes (g/100 g Protein)

Amino Acid               FAO                    Water Hyacinth
                         Reference              Leaves Grown in
                         Pattern*               Human Waste

Lysine                   5.4                    5.7
Methionine +
cystine                  3.5                    2.7
Threonine                4.0                    4.3
Isoleucine               4.0                    4.7
Leucine                  7.0                    8.3
Valine                   5.0                    5.6
Phenylalanine +
tyrosine                 6.1                    8.8
Tryptophan               0.96                   1.0
Histidine                -                      2.2
Arginine                 -                      5.2

3.3 Biogas:
Biogas, a mixture of methane and carbon dioxide, can be used in just as many ways as
town or natural gas. It can provide intense localized heat compared to energy from
solar panels/ the important uses of high-grade energy are for heating lighting, cooking
and fuel for internal combustion engines. If biogas provides energy for cooking,
lighting and fuel, it also replaces wood for fires. Thus leads to conservation of forest,
less labor requirement and fertile soil for farming, creates new business and is of
course much cleaner for air contamination.

Water hyacinth has a high content of fermentable matter and therefore a high potential
for biogas production, but the high lignin content can reduce the actual production.
The low bulk density could result in large voids with poor compaction and low feed
rates as a result, conducted trials with anaerobic digestion of agricultural waste. Rice
straw, maize stalks, cotton stalks and water hyacinths mixed with cow dung were
digested in different containers. The mixture of water hyacinth and cow dung was
found to produce more biogas per kilogram VS added than maize and cotton stalks,
but the total biogas production per kilogram DM added was lower for the water
hyacinths. The low values for total gas production was probably mostly due to the
high lignin content and low percentage of volatile solids in the water hyacinths Table
2 is a summary of reported gas yields where water hyacinth made up all or the major
part of the substrate. This shows that water hyacinths can compete well with any kind
of animal manure as a substrate for biogas production.

Table 2.

Summary of reported gas yields with water hyacinth as a main substrate

                                   Biogas          Residence time   Methane
Source                                                                          Substrate
                                   production      (days)           (%)

                                   (l/g    (l/g
                                   DM)     VS)

Chanakya et al. (1993)             0.291   0.348   300              60          W (fresh)

Chanakya et al. (1993)             0.245   0.292   300              60          W (dry)

Chynoweth et al. (1983, from
                                   –       0.19    –                –           W
Moorhead and Nordstedt, 1993)

Ellegård et al. (1983)             –       0.4     –                –           W

Hanisak (1980, from Moorhead and
                                   –       0.24    –                –           W
Nordstedt, 1993)

Moorhead and Nordstedt (1993)      –               15–60            63–67       W

Patel et al. (1993a)               0.190   0.293   8                62–66       W

Patel et al. (1993b)               0.143   0.286   8                –           W

Madamwar et al. (1991)             0.19    0.4     8                65          WC

W = water hyacinth as only substrate. WC = a mix of water hyacinth and cattle dung
was digested.

The gas produced during the process consists mainly of methane, carbon dioxide and
ammonia, but small amounts of hydrogen sulphide may occur. The proportion of
methane in the produced gas is usually up to 60%, but depends on the substrate
(Temperature, pH and pressure may alter the gas composition slightly. The specific
gravity decreases when the methane content increases).

3.4 Furniture:
There’s a company which has exported water hyacinth products for a long time- Dang
Gia company. Our group got an interview with the director- Mr Hien and we’ve got a
lot of information. The company has 2 branches (Long An-Vinh Long Province) and
gives jobs for people who live in those provinces. There are some numbers can prove
water hyacinth's products help many people and make money for handicraft
production's export.
     Income from exporting of this company: 300-400 million dollars/ year
     Income from selling water hyacinth processed : 4000-5000 VND/1 kg (0.2-
         0.3USD/1 kg)
     Made more than 200 jobs/year
     The labor earn 8000-16000 VND/ product (0.5-1USD/product)
     Every year they open some class to teach people learn how to make water
         hyacinth handicraft.
     Area of purchase water hyacinth processed: Long An, Vinh Long, Dong Thap,
         Kien Giang, Tay Ninh (mainly in West of Vietnam)………..

   And now this company is developing their products. They keep exporting to many
   countries such as: Taiwan, China, Germany, France, USA, some EU/Asian
   countries …….. (

"Thailand, the Philippines have produced water hyacinth products for 20 years but the
price is quite high. Vietnam has plentiful material, lower labor fee, fine work
experience and just need to design more novel products............Vietnam will be the
best supplier water hyacinth products in the world" Mr. David Kao-director of Appolo
company (Taiwan)-which exports handicraft production company specifically to EU
 Water hyacinth is not only help people have jobs but also earn money for Vietnamese
     2004 Tai Tri company exported 10 containers with 9500 products to USA and
        got more than 1 billion USD
     There are some companies which also supply high-quality water hyacinth
        products for 5 stars resorts.
     Average income of the workers: 20000-30000 VND/day (1.2-2 USD/day)
     2001-2005 Dong Thap province makes more than 1000 work/ year
     Our mission in 2010 is to reach at 118 million dollars with 40000 workers
     2003 income from exporting water hyacinth products: 360 million USD
     2004 income from exporting water hyacinth products: 430 million USD
     Distribution: An Giang, Phu Tan, Cho Moi, Thap Muoi, Thanh Binh, Tam
        Nong, Vinh Long, Cao Lanh………
There are 7 steps to make water hyacinth products (the information was gotten
from Dang Gia Company)
   1. Collecting water hyacinth processed

                          Collecting water hyacinth

   2. The company buys water hyacinth

   3. Standard for good water hyacinth:
    The length must be from 50 cm-80 cm
    The weight of the body

   4.   Dry out:
       Hand-made: under the sunlight
       Machine: oven from 30-40 degree
       Choose dried water hyacinth which has the same color

   5. Weave dried water hyacinth after soaking them into water in few seconds

   6.   Dry again to protect complete products from being moldy
       In dry season: put dried products under sunshine (about 2 hours)
       In rainy: put dry products by oven 30 degree-40 degree ( about 4 hours)
       Spray chemicals which keep products strong (the chemicals is not
        poisonous, it's really good for protecting environment too)

   7.   Products are complete
                       Water hyacinth products

4. Conclusions:
Although, water hyacinth is known as the worst aquatic weed in the world, in
Vietnam, we’ve researched on water hyacinth our project shows that water hyacinth is
not as bad as we think.
As we mentioned above there are 3 ways to control growth of water hyacinth. Two of
them, both Chemical and Biological have side affects besides that they take long time
to get the result.
Instead of waiting for the result of biological and chemical treatment, why don’t we
use physical treatment? Actually, in Vietnam, labor fee is lower than some countries
we matched, the more water hyacinth plant expands, and the more chance for
unemployed people to get jobs and the more Vietnam economy improves.
Beside economics advantages, in Vietnam it’s also a nutritious food for people. In
countryside, people can find it easily. They don’t use it directly; first they will choose
the best part of water hyacinth (flower, stem…) and mix it with another ingredient
such as: shrimp, meat, fish, lemon and vegetable. This kind of food is not only
delicious but also nutritious (according to the nutrition fact table above) so why don’t
we make it as a common food?
Moreover, water hyacinth furniture has been exported to many countries. It becomes
more and more common because of quality and appearance, the price is quite
reasonable. European customers do like hand -made handicrafts and water hyacinth
products are known as the best handicraft product now. That’s why we should take
use of this plant to make a good preparation for Vietnam handicraft industry to step
into a new world.

*If we had enough instruments for bioremediation we would like to have
installed systems and equipment for Saigon River.

                              Saigon River

The country which has more than 2000 rivers, lakes and streams like it or not it is
inevitably attracts mosquitoes and some kinds of insect, which cause diseases such as
malaria. Protection from this problem is to take lariam- tablet once in a week.
5. Sources:



-Soner EFE- Zeki DENGIZ-Aram KENCI, Microbiology book, Biology series, 2005,
page 32, 42, 43

-Cung Kim Tien, Biological dictionary, 2003

-Raven Johnson, Campbell Biology-sixth edition, 2002, page 685, 781

-Tu dien bach khoa sinh hoc, Ban tu dien nha xuat ban khoa hoc va ki thuat( Biology
dictionary, Science and Technology publisher) page 1955

-Elsevier Science Ltd (January 1987), Water Hyacinth (Aquatic Plant Studies, No 1)

-Gabriel Tieella, Introduction to medical immunology, fourth edition, page 321

-Elsevier (January 2007),   Water hyacinths as a resource in agriculture and energy
production: A literature review [An article from: Waste Management]

6. Special thanks:
We would like to thank to Mr. Ali Kutlu who supports us, Dang Gia Company which
gave us a lot of useful information, Ms. Thu-biology teacher in HIBS, Van Lang
university-Vice Dean Ms. Dieu for her advice and Dr. Ensar for giving information
about illness, Thanh-our friend for helping us to get pictures. And especially to Mr.
Oncu who guides us through the project.

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