Earlier this year they made a breakthrough when they managed to overcome certain kinds of pulping problems and produced different kinds of paper and paper boards. However, the cost-benefit analysis of this method is still to be worked out.
Thygarajan explains that only the stalk is used in the new method. He says: “It is chopped into pieces three to five cms long and then cooked with chemicals in a five litre capacity stainless steel autoclave at temperatures of 120 to 130 degrees centigrade for about two hours.
The cooked material is washed with water and the pulp bleached with hypochlorite in two stages with an intermediate alkali wash. The pulp is then beaten into paper.” The paper with high water resistance shows appreciable strength, appearance and smoothness suitable for writing and printing.
Beside this, other varieties of papers and boards for use as file covers and cards can also be made satisfactorily in hand made paper units. However the tear and folding strengths are lower than those prepared with conventional raw materials. Thygarajan says the RRL process can be used in rural areas where water hyacinth is in abundance.
Paper making is only one of the potential uses of the water hyacinth. Under the Commonwealth project in which Bangladesh. Egypt, Fiji, Guyana, Malaysia, Papua New Guinea and Sri Lanka are also participating, each country has been assigned to examine different possible uses.
Besides studying the possibilities of making paper, India, along with Bangladesh and Fiji, is also studying the possibility of bio-gas production using different kinds of digestors.
Malaysia is investigating the role of water hyacinth in treating industrial effluents. The uncontrolled growth of the plant is the result of its extraordinary capacity to accumulate large amounts of nutrients and it is, therefore, an ideal biological filter of water. And it can absorb heavy metals like cadmium, nickel and mercury besides potent carcinogens and could also be used to concentrate and reclaim valuable metal.
Malaysian researchers have also reported that a regular cycle of pig and fish production is maintained by growing water hyacinth for use as pig feed and draining the washings from the pig stys into water to fertilise plant growth and increase the food chain base for fish as well.
Perhaps the most fascinating study is the water hyacinth’s potential as food for humans. A researcher in Florida discovered that hyacinth can be converted into a product that is high in crude protein, the leaves dried in an oven and ground into a light green powder which has a slightly spicy smell and a taste similar to tea.
Perhaps one of the most novel methods of control is being experimented with in Georgetown, Guyana. The manatee, a herbivorous aquatic mammal, is used to control the water hyacinth as well as other vegetation.
The use of plants and pathogens in biological control is being studied in Sri Lanka. But there are fears that biological control methods may not be feasible on a commercial scale.
There are experiences to show that eradication instead of solving environmental problems may actually bring about more acute problems associated with the eutrophication of natural waters. When water hyacinths were wiped out with herbicide in Lake Seminole it was soon replaced by another pest, the alligator weed.
Although substantial progress has been made in finding useful applications for the water hyacinth there is no denying that in many countries the plant is an environmental hazard. The plant still grows faster than it can be used and for the moment the only way of getting rid of it is to employ large numbers of people to remove it manually.