6 November 2013
UK’s first production of eco-friendly, ultra-pure fertiliser for crops and turf.
A new technology that creates phosphorous-based fertiliser from sewage could hold the key to securing future global food supplies, experts announced today.
A £2m nutrient-recovery reactor, the first of its kind in Europe, is now producing sanitised fertiliser, purer than any other, from the unique vintage of wastewater coming out of Slough in Berkshire. This sustainable source of phosphorous, the key ingredient in fertiliser, whose price has increased by 500% since 2007, is a welcome alternative to mining phosphate rock from dwindling, non-renewable reserves.
The UK uses 138,000 tonnes a year of the phosphate fertiliser. All of it is imported from abroad. This adds to the costs, not to mention the reliance on external sources for such a vital resource, which is used to produce all food consumed by human beings.
Mineable reserves of phosphorus, in countries like Morocco, the US and China, are set to be completely depleted in 100 years, according to some experts, while others say ‘peak phosphorous’* will occur as early as the mid-2030s, after which it is expected to become increasingly scarce and expensive.
“With the world’s affordable mineable reserves of phosphorous set to start running out in the next 20 to 30 years, this new technology could offer a solution to securing global food supplies over the coming decades,” said Peter Melchett, policy director at the Soil Association.
“Without fertilisation from phosphorous, wheat crop yields will fall by more than half. Meanwhile, as the planet’s population is predicted to hit nine billion by 2050, demand for food will increase. Sustainable alternative sources of phosphorous, like this reactor at Slough sewage works, are vital if we are to keep pace with this demand.”
While the source for the fertiliser produced by the new facility may be dirty, the product itself, Crystal Green, is cleaner than anything else on the market. Heavy metals content, in particular, is lower by an order of magnitude in Crystal Green compared to traditionally sourced fertilisers.
Nutrient-recovery facilities like the new one at Slough sewage works are ideally suited to sewage works in industrialised areas. High-strength organic waste from businesses on the Slough Trading Estate, immortalised in BBC television series The Office, means wastewater entering the works is rich in in the nutrients ammonia and phosphorus, which can cause struvite.
If left unchecked struvite settles as a rock-like scale on pipes at the sewage works until it clogs them completely. But Slough’s new reactor, built by Ostara Nutrient Recovery, makes phosphorous settle in the form of struvite in a controlled setting, turning it into crystalline fertiliser pellets, which the company markets under the brand name Crystal Green.
With the new facility up and running Thames Water expects to save up to £200,000 a year, which it has until now spent on chemical dosing to clear pipes of struvite at Slough. All such operational savings put a downward pressure on customers’ bills.
The new reactor will also improve the quality of treated effluent leaving the sewage works, reducing nutrient levels and in turn reducing algae growth in rivers and streams, which can suck oxygen out of watercourses leaving little for fish and other wildlife.
The reactor is expected to sustainably produce 150 tonnes a year - half a tonne a day - of top-grade fertiliser for sale to crop-growers, golf green-keepers and gardeners.
All of the UK’s imported fertiliser is “water-soluble,” and so is less crop-efficient and poses a higher environmental risk due to it leaching into waterways causing surges in algal growth. The Crystal Green fertiliser being produced at Slough avoids these problems: as well as coming from a sustainable source, it is slow-release and so much more efficient for plants and kinder to the environment.
“This new facility is a model for sustainable innovation in the UK and indeed across Europe,” said Phillip Abrary, president and chief executive of Ostara. “Removing nutrients from where they shouldn’t be - in our waterways - and using them to create a new generation of enhanced-efficiency fertiliser is the smart thing to do economically and the right thing to do environmentally.”
Piers Clark, commercial director for Thames Water, said: “This is a classic win:win. We are producing eco-friendly steroids for plants, while also tackling the costly problem of struvite fouling up pipes at our works. The cash and carbon cost of digging phosphate out of the ground in a far-flung foreign clime then shipping it back to Britain makes no sense when compared to the local, sustainable process of our reactor in Slough. As we gain experience with this new technology, we intend to evaluate its suitability for installation at other Thames Water plants in the UK.”
He added: "Slough has taken some stick over the years, from the likes of poet John Betjeman and Ricky Gervais, but this scheme is rebranding it as an eco-warrior at the forefront of the global effort to save the planet.”
Slough is not the first place to experience this headache: struvite is also known to have scaled the waste pipes of the Ancient Greeks as far back as 300BC. Ostara Nutrient Recovery Technologies is based in Vancouver, Canada. Its North American facilities have been in operation since 2009 and its Crystal Green fertiliser is sold throughout North America and has received Environment Agency approval for sale in the UK.
*Peak phosphorous (Source: Soil Association):
Worldwide 158 million tonnes of phosphate rock is mined every year, but the supply is finite. Recent analysis suggests that we may hit ‘peak’ phosphate as early as 2033, after which supplies will become increasingly scarce and more expensive. This critical issue is missing from the global policy agenda. Without fertilisation from phosphorus it has been estimated that wheat yields could more than halve in coming decades, falling from nine tonnes.