Connecting Waterpeople

Unchartered waters: the nutrient siege

  • Unchartered waters: the nutrient siege

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When water turns green, it symbolizes a bigger problem than we can imagine.

Industrial effluents, sewage runoffs and over fertilization bring about the massive problem of nutrient pollution in water bodies.

When nutrients such as nitrates and phosphates accumulate in water, they trigger a build up of algae which decay and are broken down by bacteria leading to reduced water oxygen.

Low oxygen levels in water leads to fish death affecting surrounding communities.

But what’s of most importance is the sources of these nutrients.


Since effluents from food and pulp related industries contain high levels of nutrients, there’s need for treatment to lower the threshold levels before release.

But this isn’t usually the case.

These nutrients end up accumulating in rivers and runoffs and are usually carried miles away to inland water bodies leading to algal build up.

But the main concern with industries arises from the cocktail of pollutants that they release.

A mixture of industrial chemicals, metals, dyes, plasticizers etc. may affect water bodies in more ways than we can imagine.

But besides industries, some urban centres and municipalities struggle to dispose off human waste.

This sanitation struggle usually gives rise to another nutrient conduit which damages our environment in a number of ways.

Sewage effluents

Since sewage by itself is naturally nutrient rich, treatment before disposal is of great importance.

But since wastewater treatment is sometimes inefficient, release of nutrient rich sewage effluents affects our environment and water bodies.

Construction of pit latrines next to sunken boreholes also creates bigger problems because of the mobility of nitrates which are highly soluble in water.

It’s not uncommon to find boreholes with nitrate levels way above the maximum allowable WHO limit of 50mg/l.

Consuming such water over the long haul exposes infants to blood health complications together with increasing the risk of cancer development in adults.

But besides sewage, livestock and crop farming are another bunch of culprits in this nutrient pollution problem.


Use of mineral fertilizers and intensive livestock farming are both practices we can’t avoid due to the population bubble.

Since mineral fertilizers are manufactured from phosphate rocks, over fertilization leads to washing off of phosphates into surrounding water bodies during rainy seasons.

Since phosphates are sparingly soluble in water, they attach to sediments which are carried off to distant water bodies causing environmental stress far from their locations of origin.

This problem is compounded with other poor land management methods such as over application of manure.

The global nutrient imbalance created by the misuse of phosphate fertilizers is seen in the prices of fertilizers in the market.

As the mineral is wasted, more is mined depleting reserves in the process.

What this means is that ultimately, phosphate recovery technologies will prove more useful in the future to stabilize fertilizer costs.


One of those materials touted as a possible solution to this problem is biochar.

Biochar is formed when agricultural wastes are pyrolyzed (burnt in the absence of oxygen) producing a highly porous, carbon rich substance capable of trapping stuff in it’s pores.

Though biochar is used in a number of applications such as air filtration, water treatment and as a soil amendment, it could find good use as a material capable of absorbing nutrients from polluted water.

But what makes biochar stand out is it’s ability not only to remove nutrients from water but it’s reuse in agriculture when applied as a soil conditioner.


Nutrient pollution especially the loss of phosphates is a growing problem needing innovative players to rise to the occasion and tackle it.

Tackling this environmental problem is tantamount to improving food security because of nutrient recovery for reuse in agriculture.

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