Sacred Plant-Removes Heavy Metals

“From the sacred fountains of Chinese Royal family to lakes of Bengaluru they have encountered variety of waters and when they are happy with the quality of water they cannot control and pop out. The water is just right for this native of Amazon- ‘Eichhornia Crassipes or Water hyacinth’ to make this lake a field of blue blossoms under the blue skies. Credit goes to the citizens of the area who have kept the lake as clean as possible from 2009 because hyacinth blooms only in clean and nontoxic waters. With so many constructions going around maybe this is the last we will see a field of hyacinths. Capturing these rarely seen blossoms for future. “

Why was Hyacinth so sacred to Chinese royal family that no one was allowed to take it out of the fountains which were heavily guarded?

Water Hyacinth: A Blessing Not a Curse

People(lazy) dealing with aquatic plants term water hyacinth the worst aquatic weed in the world because of its alarming growth rate  causing  serious social, economic and environmental problems including ecological imbalance in lakes resulting in choking of fish life and native aquatic plants.

But its a boon in disguise if we are not completely lazy and keep its growth under control regularly. Just like its fast growth rate it sucks up pollutants from waste water which includes sewage and industrial effluents .

The first person to recognize the full potential of water hyacinths (Eichhornia crassipes) was  agricultural scientist Sir Albert Howard, founder of the organic farming movement, while working in India in the 1920s.

He found it to be very efficient in purifying sewage effluent. He also found that an acre of water hyacinth could remove 2.4 tons of ammonium sulphate (nitrogen fertilizer) in one hour, and phosphorus just as efficiently. One research study found that planting one hectare of water hyacinth removed the equivalent of nitrogen and phosphorus produced daily by 800 persons.

Its almost magical in its  phytoremediation properties as it can soak up soluble heavy metal ions and cyanide in polluted waters. Many studies spanned across decades have shown that water hyacinth has high removal rates for various dye stuffs and heavy metals like iron (Fe), zinc (Zn), copper (Cu), chromium (Cr), cadmium (Cd), manganese (Mn), mercury (Hg) and arsenic (As) from aqueous solutions.

One study to clean up and reuse water by means of hyacinth was undertaken in Iraq showing promising results. UN report gives details of this study where they used hyacinth for waste water treatment using this simple technology with very little cost. The technology also reduced nitrogen and phosphorus in the wastewater. The removal percentage was about 80% for nitrogen and 48% for phosphorus. These percentages depended on the surface area of the pond, water flow rate and efficiency of the system operation. It also removed heavy metals . How does this plant removes pollutants? Check the above  mentioned UN report.

Even after showing such good results  it has still not been applied in our cities water bodies. Why? Because of regular control measures needed to keep its growth under control. Its not an impossible task. One time investment in boats and mechanical harvesters is all it needs and we are never lacking in manpower in India.

Secondly one may say what all can be done with so much of harvested hyacinth . Water hyacinth plant also has abundant nitrogen content and it has been harvested and used a substrate for biogas production. Heavy metal recovery from the sludge thus produced is an established technology now. On the other hand  several woven items like bags and baskets can be made out of hyacinth . “MAPSAS” -An NGO in Bangalore is doing this good work for the upliftment of poor.

Go for Hyacinth next time!


Nature Lover, Bangalore

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