The problem with phosphorus

Phosphorus is an essential mineral for humans, livestock and crops. It's vital for human health because it helps to keep our blood balanced and our nerves and muscles working; it works in tandem with calcium to keep our bones and teeth strong, and it helps our bodies turn fat, carbs and protein into energy. Phosphorus is found naturally in meat, fish, dairy products, beans, grains, nuts and seeds.

Phosphorus in agriculture

Phosphorus is found naturally in soil, but its importance as a nutrient means farmers have traditionally used it as a fertiliser in order to boost yields. Unfortunately this practice has led to problems. Firstly, waste phosphorus runs off from the fields and pollutes our waters. Secondly, the mined phosphorus used for fertiliser comes from finite resources, which could run out within five decades. This will mean a rise in prices for fertilisers and a lowering of yields for farmers who can’t afford them, resulting in a rise in food prices and more food shortages.

In Cambridge, an agricultural consultancy company has been experimenting with phosphorus use in barley growth. Specifically, they stopped adding phosphorus to the soil to find out how that would affect crop growth - they discovered that, because there was enough legacy phosphorus already in the ground, it took eight years before there was a fall in phosphorus levels in the plants.

Our Phosphorus Future

Ironically, even though phosphorus is an essential mineral for humans and an important nutrient for crops, our misuse of it is leading to pollution problems, and in a report just published - Our Phosphorus Future - scientists are calling for action. The overuse of fertilisers has not only led to millions of tonnes of phosphorus being released into rivers and lakes, with a devastating impact on the environment, it has also depleted global resources of this precious mineral. For example, phosphorus pollution in water helps to accelerate the growth of algae which produce toxins that are harmful to animals and any humans who come into contact with contaminated water. In the UK, it’s estimated that 75% of our lakes and 54% of our rivers are failing phosphorus standards, costing the country around £170m a year in pollution costs.

So, on the one hand, phosphorus pollution is causing a problem, and on the other, the cost of mined phosphorus has risen dramatically - by around 400% since 2020 - which means poorer farmers are unable to afford to fertilise their crops, which will lead to lower yields and higher food prices.

Unsurprisingly, Our Phosphorus Future’s authors are calling for global action - they want a 50% reduction in pollution and a 50% increase in phosphorus recycling by 2050. It is thought that, globally, recycling waste phosphorus will return 8.5 million tonnes to our farms, which could save $20 billion in annual fertiliser costs and provide enough food for four times the population. On the other hand, they estimate that doing nothing would eventually cost $300 billion to put right.

Phosphorus recycling from wastewater

Wastewater contains a significant amount of phosphorus, and there are a number of projects underway that are looking for new ways of recycling it in sufficient quantities to make it a cost-effective exercise. Currently inorganic phosphates are chemically removed from wastewater and organic phosphates are removed by bacteria. Phosphorus can also be physically removed with the use of filters, or it can be removed using a combination of these methods.

Projects that are using nature to remove phosphorus from our water

However, there is another, more natural way of managing phosphorus in our water. At the recent Utility Week Live conference, delegates heard about projects being run by water companies to remove phosphorus from wastewater using natural solutions. Severn Trent is restoring wetland areas and sites of special scientific interest using reed plants that have the ability to filter phosphates. In Norfolk, a project between Anglian Water, the Environment Agency and the Norfolk Rivers Trust has constructed wetlands with areas of open shallow water (shallow cells) and native plants that absorb phosphorus, cleaning water which can then be released into the River Ingol.

So it is possible to fertilise our crops at the same time as keeping our waters clean and not depleting the planet of its finite mineral supply.

Wastewater treatment services

Castle Water offer a variety of wastewater treatment services,  including nitrogen and phosphorus wastewater treatment . We work collaboratively with you to identify your needs so we can advise wastewater treatment solutions that are tailored to your business specifically.

Find out more about our business water services and switch to Castle Water to start saving up to 80% on your fixed water charges.