By Professor Ana Soares, Professor of Biotechnology Engineering at Cranfield University

In the domain of wastewater treatment, it’s remarkable to note that England and Wales have poured an eye-watering £8 billion in removing phosphorus, with another 5 billion in the next 5 years over the last decade and a half. However, amidst this financial outpouring, a troubling reality emerges: the conventional techniques employed for phosphorus removal are riddled with challenges.

These methods lean heavily on iron-based coagulants, which, though effective to a degree, exact a heavy toll on the environment. The excessive use of chemicals not only drives up operational costs but also leaves a substantial carbon footprint in its wake, contributing to the alarming rise in greenhouse gas emissions. Moreover, these methods generate copious amounts of sludge, exacerbating the burden on waste management systems. It’s abundantly clear that a paradigm shift is imperative—a shift towards more sustainable alternatives that can alleviate the strain on our ecosystems while effectively treating wastewater.

While certain alternatives, such as algae and ion exchange resins, show promise, they encounter practical limitations. Algae, for instance, require ample sunshine and vast expanses of land, making them unsuitable for the UK’s climate. On the other hand, ion exchange resins and chemical reactors that precipitate phosphorus as struvite demand high chemical input and are effective only at high phosphorus concentrations.

Responding to these challenges, Cranfield University, in collaboration with Microvi, has embarked on a pioneering endeavour. Their ground-breaking technology harnesses the remarkable properties of bio-mineral forming microorganisms to extract phosphorus from wastewater. These microorganisms exhibit a remarkable ability to selectively capture phosphorus and ammonia, concentrating them into crystalline structures that can be in return separated and used as resource. Lab tests have demonstrated the efficacy of this approach, achieving up to 90% phosphorus removal—a milestone achievement in the field.

However, challenges persisted in retaining non-native microorganisms within wastewater systems. To address this hurdle, Microvi has developed innovative biocatalysts, ensuring the efficient retention of microorganisms within bioreactors. By employing continuous flow reactors equipped with these bio-mineral biocatalysts, phosphorus removal rates of up to 96% can be achieved, yielding effluent with phosphorus concentrations below 2 mg P/L. This transformative process has been named the bio-mineral phosphorus removal (BMPR) process. The other major advantage of this processes is the recovery of precipitates that have a clear crystalline structure and have been identifies as struvite, with high purity, as demonstrated after pathogens, metals and pharmaceuticals analysis.

The bio-mineral phosphorus removal (BMPR) process was selected amongst 10 innovations are sharing in up to £4.5 million, to demonstrate how bold solutions can help solve the biggest challenges facing the water sector, today and into the future. The Water Discovery Challenge is a part of a series of competitions from Ofwat, delivered collaboratively by Challenge Works with Arup and Isle Utilities, designed to drive innovation and collaboration in the sector to benefit customers, society, and the environment.

Inherent risks accompany wastewater treatment innovations. Recognising this, Cranfield University and its partners are committed to ensuring the reliability and cost-effectiveness of the (BMPR) process through rigorous testing at large scale and stakeholder engagement. Drawing upon past successes in commercialising nitrogen and carbon removal technologies, they seek to catalyse widespread adoption of the bio-mineral phosphorus removal process, thereby enhancing the sustainability and resilience of the water sector for generations to come.