Experts struggle to find ways to improve phosphorus recycling
Most phosphorus used in fertiliser is wasted and ends up polluting water
Securing sufficient phosphorus for agricultural production is one of the big challenges for the future. Supplies of phosphorus used in the production of fertiliser are dwindling, and deposits exist only in the territory of a few countries.
At the same time, vast amounts of the valuable element are wasted. Only a fifth of the 16 million tons of phosphorus ends up in human nutrition. Most of it flows into rivers, lakes and seas, where it causes serious environmental damage; phosphorus is also a fertiliser for algae, which depletes oxygen supplies when used to excess.
The problem is that phosphorus ends up dispersed over a wide area and is difficult to recover for re-use. However, Jouni Lehtoranta, a special researcher at the Finnish Environment Institute (SYKE), points out that unlike resources such as oil, coal, and natural gas, phosphorus can be recycled.
Recycling phosphorus is an idea that is still in its early stages. However, as phosphorus cannot be manufactured artificially, developing more efficient ways of recycling is becoming increasingly important.
“The present system is set up on the assumption that phosphorus is used only once. The production of food depends on a constant supply of phosphorus”, Lehtoranta says.
The efficient use of animal manure would be a great benefit, as large amounts of phosphorus end up in the manure, which is not used efficiently now because industrial animal production is no longer linked closely with grain farming.
Lehtoranta has studied phosphorus flows and has considered different options for recycling.
“We need to reduce over-fertilisation. Animal food, manure, and plant waste, human waste, and all other biologically based material that emerges in production needs to be used more efficiently”, Lehtoranta says.
Shortening the food chain would also save phosphorus: “We should use less meat and milk products.”
Preparations are underway around the world to deal with the looming shortage of phosphorus.
Western Europe is largely dependent on imports, and in February the EU drew up a “Green Paper”, which is a plan to secure sustainable food production. One aim is to increase the recycling of phosphorus through improved agricultural technology, increase the utilisation of phosphorus in household waste, to work for the more efficient processing of manure, and to reduce food wastage.
Sweden aims to achieve a 60 per cent recycling rate of phosphorus in waste water by 2015 by fertilising fields with sludge from sewage. Finland, meanwhile, hopes to become a model country in recycling nutrients in order to improve the state of the Archipelago Sea.
There is plenty of phosphorus at the sea bottom in waters near Finland.
Lehtoranta feels that it would not be a viable proposition for now to start dredging it from the bottom, but he says that fishing could be one way to recover phosphorus from the sea, as about one per cent of the fresh weight of fish comprises phosphorus.
Previously in HS International Edition:
Siilinjärvi mine only source of phosphate ore in Western Europe (2.5.2012)
No agreement near over Russian phosphorus emissions (7.2.2012)
NEWS ANALYSIS: Phosphorus flows – information doesn’t (31.1.2012)
Improved St. Petersburg sewage treatment reduces pollution in eastern reaches of Gulf of Finland (27.8.2010)