Water Hyacinth: Unlikely Hero

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Water Hyacinth (ECCP archives, SMART Cebu 2010-2011)

Invasion seems like negative predicament.  But for the Tominé Reservoir in Bogota, Colombia, invasion is what saved it.  In 2003, the non-indigenous water hyacinth reached water reservoirs supplying 4% of Bogota’s potable water, and also generating electricity for the region.  Due to the combined effects of wastewater discharge, agrochemicals, deforestation and soil erosion, water quality had gone down over the years.  Traditional ways of managing the water system had high environmental impact at zero cost efficiency.

Then the water hyacinth started appearing.  A number of studies had been done by this time on its purifying capabilities.  So instead of eradicating a sworn enemy, the aquatic plants which already occupied 7.5% of the surface, were corralled for a scientific project.  The pre-invasion water quality measurements were dug up, the post-invasion water quality measured and then they waited for nature to take its role. (Water Quality Improvement of a Reservoir Invaded by an Exotic Macrophyte)

Could it be that where waste water was, is exactly where the water hyacinth needed to be?

An environmental engineer of University of Andes confirms that “Today Tominé Reservoir is still in good health thanks to water hyacinth.”

The numbers add up—or in this case drop down—in a study of Lake Caohai in China first implemented in 2011.  After 7 months of planting the water hyacinth, the average  TN (Total Nitrogen), NH4(+)-N (Ammonia) and NO3(-)-N (Nitrate/Nitrite) significantly reduced from 13.8, 4.7 and 5.8mgL(-1) respectively, down to 3.3, 0.02, and 0.8mgL(-1).

An experimental study in Iraq initially implemented in September of 1994 expounds on the simple purifying mechanism of the water plant.  Every part of it has been nature-engineered for this purpose.  The roots, which under best conditions can extend 10-30cm beneath the surface, traps suspended solids in the water.  The wide rimmed leaves are specifically shaped to block out sunlight and its UV rays that kill microorganisms.  Working harmoniously, an ecosystem (a slimy film) is formed for tiny microbes to feed off the solid organic matter.  Without sunlight, the algae can’t live beneath, leaving the “food” entirely for the microorganisms.  And this it does with gusto, turning suspended solids into sediments.  As these sediments grow heavier, gravity pulls them to the bottom, leaving the water clearer.

Although a balance between the risk of wild proliferation and its positive impact needs to be struck, since water hyacinths are here to stay, it can finally stay for a productive reason.

Sources:
Naufal A.Al-Masri. 1999. Iraq Country Report, Project for the Preparation of Sourcebook for Alternative Technologies for Freshwater Augmentation in West Asia Region. Internal Technical Report, ACSAD, Damascus, Syria.
Rodriguez, M, et al. 2011. Water Quality Improvement of a Reservoir Invaded by an Exotic Macrophyte. Bogota, Colombia.
http://www.unep.or.jp/ietc/publications/techpublications/techpub-8f/c/Iraq1.asp
http://conservationmagazine.org/2014/03/water-hyacinth-in-kings-bay/
https://www.ncbi.nlm.nih.gov/labs/articles/23582406/
http://www.bioone.org/doi/abs/10.1614/IPSM-D-11-00023.1
http://www.switchurbanwater.eu/outputs/pdfs/W1-1_CBOG_RPT_D1.1.6_Strategic_Planning_Process_-_Tomine.pdf
Z Wang et al. Chemosphere 92 (2), 177-183. 2013 Apr 09.
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