CIRCULAR REVOLUTION: FROM WASTEWATER TO FERTILIZERS

Phosphorus is a unique substance.

It’s one of the three most important macronutrients needed for agriculture yet it’s the only one among the three that is mined.

Most of global phosphorus is mined in Morocco and the Western Sahara Republic – which Morocco has laid claim to for decades.

Phosphorus is unearthed as rock phosphate which is further processed into phosphate fertilizers such as diammonium phosphate (DAP) or tri-superphosphate (TSP).

Farmers then use this fertilizer for sowing seeds and seedlings leading to robust root development and good yields.

The process of mining and using phosphorus (also called phosphate) has created a well-oiled system of processing and supply of global fertilizer which has guaranteed constant food production over time.

But is this really sustainable?

PEAK PHOSPHORUS

Some scientists are tracking phosphorus reserves over time and used it to predict a phenomenon called ‘peak phosphorus’.

Since phosphorus is mined, then the reserves will deplete at some point.

Peak phosphorus signifies a time when production will get to it’s peak after which a decline in production will follow..

Now peak phosphorus is a concept that is debated by many.

But we still can’t escape the fact that phosphorus production will decline in days to come – simply because it is mined.

Which leads me to the question…

Are there any other possible phosphorus reserves we could use besides mining it?

Phosphorus is an element which cannot be degraded further.

In other words, it will keep on circulating within the environment in different forms.

Environmentalists call this the phosphorus cycle.

Plants assimilate it and later shed it off into the soil after they die.

But plants are not the only players in this game.

Humans and animals also take up phosphorus from food and use it to build useful substances such as DNA.

So phosphorus is in plenty in animal excreta and carcasses.

If that’s so, then here are some possible unconventional sources for agricultural phosphorus.

FOOD PROCESSING INDUSTRIES

Circular economy principles dictate using what we view as waste to recover, reuse and recycle what’s of value.

It may also mean using knowhow to convert waste into value.

Since food processing industries use plant and animal inputs, most of their effluents have a very high concentration of phosphorus.

A case in point is slaughterhouse wastewater which might have as much as nearly 1 gram of phosphorus per liter.

A gram might look small but given that thousands of liters being are released on an hourly basis, this constitutes a very large amount of phosphorus.

Simple phosphorus recovery strategies might include using materials that discriminately ‘soak up’ for reuse in agriculture.

But food and processing industries aren’t the only option around.

DOMESTIC SEWAGE

It would surprise you that human waste has a phenomenal level of phosphorus.

But it’s unfortunate that most of it ends up in our water bodies leading to build up of harmful algae and loss of aquatic biodiversity.

So what if some young innovators are willing to roll up their sleeves and dig into the muck with profits in mind?

Let me explain…

STRUVITE

A number of innovators have already found footing in this terrain by extracting a useful phosphorus based fertilizer  – struvite – from human urine.

A bit of chemistry is needed to help the mineral crystallize and make it fit for use.

Mind you, these are not soil amendments such as compost but have the potential of being categorized as actual fertilizers with an NPK rating.

Reusing circular economy to recover phosphorus is also beneficial in other ways.

REDUCTION OF CARBON FOOTPRINT

Mining uses tonnes of fossil fuels.

But what if we were to use technologies like adsorption, and precipitation to recover phosphorus?

It will save us energy costs and reduce the carbon footprint.

SO WHAT AM I SAYING?

There’s a shortage of fertilizers in many African nations.

So instead of depending on imported fertilizers, why can’t we innovate around the circular economy and produce our own?

Wherever people exist, industries are bound to thrive.

Why not reuse industrial wastewater for fertilizer production?

Why not reuse urine for the production of struvite and other minerals that could enrich soils?

These are possibilities.

But let’s make them work.