Thames Water is using innovative Canadian technology to produce the UK’s first eco-friendly, ultra-pure fertiliser phosphorous-­based fertiliser in a new £2 million plant at its Slough sewage treatment works in Berkshire.

A £2m nutrient-recovery reactor, the first of its kind in Europe, is being used to generate a sustainable source of phosphorous, the key ingredient in fertiliser, whose price has increased by 500% since 2007.

The fertiliser, known as Crystal Green is produced by Vancouver-based Ostara Nutrient Recovery Technologies. The product is cleaner than anything else on the market - heavy metals content, in particular, is lower by an order of magnitude 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 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. The new reactor, built by Vancouver-based 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.

Phillip Abrary, president and chief executive of Ostara commented:

“This new facility is a model for sustainable innovation in the UK and indeed across Europe. 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.”

With the new facility producing 150 tonnes per annum, 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 - operational savings which 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.

Technology could be rolled out to other Thames Water plants 

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.”

The UK uses 138,000 tonnes a year of the phosphate fertiliser all of it imported from abroad. 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.

New technology could be key to future global food supplies

Experts said the new technology could hold the key to securing future global food supplies and provide an alternative to mining phosphate rock from dwindling, non-renewable reserves.

“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.”

Ostara’s North American facilities have been in operation since 2009 and its Crystal Green fertiliser is sold throughout North America.  Crystal Green has received Environment Agency approval for sale in the UK.