And now peak phosphorus?
The murmurs heard a few years ago are now getting louder. The scientific community is worried and it may not be long before the mass media gets to another inconvenient truth.
Phosphorus plays an important role in the metabolism of living things – in the formation of DNA, RNA and cell membranes. In humans, it helps in bone formation. We get phosphorous from food, which in turn comes from soil or from the fertilisers applied to crops.
Most of the phosphate used in fertilisers is gouged out from mines under the ground in a damaging process called strip mining. Since phosphate is a finite resource, it is being argued that a shortage is imminent, with some predicting that it will run out by the end of this century. Many mines are degrading and yielding lower grades of phosphate.
While there is not enough data available about the actual amount of reserves, China, Morocco, US, South Africa and Jordan are said to hold 90% of the world’s phosphate deposits. With growing demand for fertilisers, spurred by food, the demand for phosphate is only expected to rise, which in turn will have a profound effect on food prices.
The most striking aspect about the problem is that phosphate is actually being excreted from living bodies day after day. Due to the modern system of diluting human wastes with water and sending it away for disposal, the precious nutrient is not only being lost but causing new problems such as eutrophication. Many lakes and streams around the world which receive an excess of phosphate from waste streams are suffering from serious ecological effects such as oxygen depletion and fish-kills.
If the phosphate from wastes were recovered and converted back into fertiliser, not only would it save millions of dollars but it could spare the environmental degradation caused both at source and sink.
Recovery of phosphorus from sewage sludge is costly. On the other hand, eco-san toilets which do not use water for flushing and diluting wastes could effectively create organic fertilisers that recycle not just phosphorus but nitrogen, potassium and other nutrients.
For many years, we have been hearing voices critical about the conventional systems of flush toilets and sewage disposal which are throwing out the proverbial baby (nutrients) with the bath water (sewage). It is time to heed these voices more seriously.
Does it make sense to go through the elaborate process of mining phosphate and then losing it all in wastewater? Agreed, it is difficult to uproot the conventional wastewater systems which are already in place in most of the big cities in the world. But there are still about 2 billion people without adequate sanitation.
Can we, at least, get it right for the unserved millions?