Phosphobrine: the innovative new process yielding agricultural fertiliser from wastewater

Ever heard of struvite? If the answer is yes, you might be aware of the destructive effect it can have on your wastewater treatment infrastructure.

Struvite is a salt that causes blockages and damage to wastewater treatment pipes and equipment. But it’s not all bad news. The minerals natural properties make it a rich source of magnesium, nitrogen and phosphorus, making it an ideal and endlessly renewable source of fertiliser for agricultural applications.

The process of extracting struvite from wastewater, in a fertiliser compatible form, dubbed Phosphobrine by SUEZ’s expert project team, represents a new and compelling process to give wastewater by-products a second life – and a novel avenue for utilities to boost the environmental, financial and operational performance of their wastewater facilities.

The Phosphobrine process was born in 2017 when two of Perth’s largest wastewater treatment plants, managed by the award-winning Aroona Alliance partnership between SUEZ, Water Corporation and Broadspectrum, faced growing operational and maintenance challenges to its complex networks as a result of accumulating struvite.

So how does it work?

The technology is placed on phosphorus-rich streams, such as centrates from pre-digestion dewatering or digested sludge centrates. This is then combined with excess desalination brine – previously released into the ocean – in a fluidised bed reactor at the right conditions for the struvite to form. Up to 90% of the phosphorus present is recovered, therefore minimizing chemical treatment and maintenance costs due to recirculated phosphorus and unwanted struvite precipitation in pipes.

What about the end product?

The Phosphobrine process captures magnesium, nitrogen and phosphorus to create a nutrient-rich agriculture grade struvite fertiliser in the form of easy-to-handle granules in a range of sizes. It’s endlessly renewable, locally produced, sustainable, and entirely made of otherwise unwanted by-products – Phosphorus is otherwise a non-renewable resource, 75% of phosphorus comes from ore extraction.

Monitoring the Phosphobrine process

A new source of revenue

Phosphobrine delivers genuine circular economy outcomes from waste, saves on costly maintenance, repair and replacement of infrastructure, and opens lucrative new revenue streams for wastewater and desalination plants. In the two full-scale pilot Phosphobrine facilities in Perth, the process has the potential to generate 3.5 tonnes of struvite daily, ready to be on-sold to agricultural operations to enrich production rather than simply going to waste and creating ongoing maintenance headaches.

It’s a win-win for utilities, industry, and the environment.

Contact a SUEZ expert today to find out the benefits of Phosphobrine for your organisation.