World Water Day 2023: How Recycling Phosphorus Can Help Feed the World

As the world’s population continues to grow, mankind needs to produce more food.
There is therefore an ever-increasing demand for synthetic and mineral fertilizers such
as phosphorus. Phosphorus however is one of the nutrients in wastewater that mankind
is wasting into our surface waters.

We extract the mineral phosphorus from mines. The production of phosphorus fertilizer
requires the use of sulfuric acid. It is coming to light however that we will be facing
global shortages of this chemical in the coming decades. The shortage of sulfuric acid is
therefore likely to cause a global phosphorus supply and food security crisis, especially
for those in low-income countries. To prevent this shortage problem, the recycling of
phosphorus from wastewater is now being recommended.

How is Phosphorus Recycled from Wastewater?
Recycling phosphorus from wastewater involves changing the pH of the sewage and
adding magnesium rich salt to produce a new compound called magnesium ammonium
phosphate. This process produces a form of phosphorus rich fertilizer called struvite.
This removal and recovery of phosphorus from wastewater prevents phosphorus
pollution in rivers and surface water.

The advantage of this method is that it does not require sulfuric acid. Dublin’s Ringsend
sewage treatment system is preventing phosphorus from entering Dublin Bay by
producing Struvite. For this reason, Ireland may want to provide struvite recovery in all
their other large urban sewage treatment plants, but this may be decades away.

Phosphorus recycling to food crops can also be achieved from separated urine. This
method will be useful for small villages and rural areas. Struvite production from
separated urine is more cost-effective because it only requires adding magnesium salt
to the urine and mixing it. This method can be easily carried out in homes or local
communities at a small scale, but for various reasons this is unlikely to be widely
implemented. It would therefore be better achieved at a national level if the urine was
collected and treated at Uisce Éireann treatment plants. This would require a new policy
for parallel treatment system for the urine. The advantage would be to produce much
larger and more commercial quantities of struvite. The removal and recycling of
phosphorus from urine has the advantage that a pure toxic metal free fertiliser is
produced that is safe for use on food crops.

In addition, Uisce Éireann will also more effectively and at a lower cost, remove the
pharmaceuticals present in separated urine, than from the discharge from municipal
sewage treatment plants.

Why Should We Recycle Phosphorus?
If mankind doesn’t recycle enough phosphorus to meet the growing global demand for
phosphorus fertilizers, then prices for fertilizer and for food will become unaffordable for
millions, especially those in low-income countries. The remaining phosphorus rock
reserves have a high contamination of cadmium that the European Union wants to
reduce and minimise. Recycling phosphorus from wastewater without metals is
therefore crucial for long term sustainable agriculture and food safety.

In my view the Struvite produced from separated urine that is very pure and does not
contain toxic metals or pharmaceuticals, will increasingly be accepted as the safest form
of recycled phosphorus for use in the food chain.

How Can You Get Involved?
Are you concerned that pure phosphorus recycling to agriculture is still not a national
water treatment policy and is not happening in your local area? Are you are concerned
about algae and phosphorus pollution emerging in nearby surface waters. Do you want
to play a part in preventing future food crisis? Then you or your local community can
start by making struvite yourself from separated urine. Herr Ltd offers domestic and
small community phosphorus recycling systems with low running costs that are easy
and safe to use and require minimal maintenance.

As a further step, by automatically growing enough flowers in glasshouse hydroponic
systems with the remaining left-over urine, this will treat the remaining nitrogen and
pharmaceuticals that are still present to prevent these pollutants from entering
groundwater. Over long composting periods using mushroom mycelium, the harvested
dead flower biomass along with kitchen food waste can be composted to deal with the
remaining pharmaceutical and nitrogen pollutants.

Conclusion
Recycling phosphorus is a useful tool to prevent phosphorus pollution and is crucial for
sustainable agriculture and food security. With the European Union concerns about
toxic cadmium in imported mineral phosphorus, and the coming shortage of sulfuric
acid, and the consequent rising cost for phosphorus fertiliser; mankind needs to
implement this alternative method to prevent phosphorus pollution and the production of
a pure phosphorus fertilizer.

If you’re interested in learning more about phosphorus recycling or want to get involved,
contact Ollan Herr Ltd today. www.herr.ie