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Green water: a deeper problem

  • Green water: deeper problem

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Let not green colored water from the nearby lake fool you into taking a sip.

The greenery is brought about by the presence of blue green algae; microorganisms that thrive on pollutants in our water bodies.


Though the word ‘nutrients‘ in a normal sense refers substances that add value to growth, in environmental terms, it represents notorious pollutants.

And that’s the precise tag name given to nitrates and phosphates in our water bodies.

Being primary constituents of fertilizers, sewage and some industrial effluents nitrates and phosphates are no strangers to our lakes, steams and runoffs.

Take a classic example of Lake Victoria, the second largest freshwater lake in the world who’s shores are colonized by bluish green algae and the notorious water hyacinths.

As long as human life exists, phosphates and nitrates will continue playing a role in the wasting away of our inland fresh water bodies through a hazardous process with a long name: eutrophication.


Eutrophication is a stage of lake deterioration triggered by the build up of algae and hyacinths which thrive on nutrients.

Yes…those same nutrients our crops thrive on, lead to a whole new problem when they are in water.

This build up of algal and plant matter in lakes comes with it’s fair share of challenges one of which is the blockage of sunlight and reduced aquatic oxygen which reduces aquatic life.

Fish ports that once produced a tonne of fish suddenly start having unexplained reductions in fish catch.

Nutrient removal 

One of the touted solutions to this challenge is in improving treatment technologies for industrial effluents and sewage discharge before release into the environment.

Several low cost materials have been tried and tested in this regard including rice husks, biochar and activated carbon.

But beyond nutrient removal, another hazard lurks in these waters endangering the health of those who drink it.


When the blue green algae die, they release microcystins; liver toxins known to linger in water for weeks if not months.

Microcystins haven’t been known to kill people but sure do bring about long term liver damage if ingested continuously over time.


Rice husks have been tried and tested as a possible cheap material capable filtering off these toxins with relative efficiency.

However, innovators and water technologists have a role cut out for them especially among communities relying on nutrient polluted water for sustenance.

Such water treatment initiatives will not only tackle unique environmental challenges but also long-term health risks posed by such toxins e.g. liver damage.

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