Phosphorus removal at rural wastewater treatment | An update from the Ofwate funded project ALT-P

A collaborative study led by United Utilities, known as the ALT-P project, has explored sustainable alternatives to traditional chemical treatments for phosphorus removal in rural wastewater treatment works. The project, involving partners such as Southern Water, Wessex Water, the University of Portsmouth, and others, received funding from Ofwat’s Water Breakthrough Challenge in 2021 and is set to conclude in November 2025.

The research focused on three primary methods:

Electrocoagulation: This technique employs electrical reactions to aggregate particles, effectively removing phosphorus without the need for liquid chemical dosing. Trials at United Utilities’ Woolton wastewater treatment works in Liverpool demonstrated its efficacy, highlighting benefits such as reduced impact on alkalinity, elimination of health and safety risks associated with chemical storage, and potential carbon footprint reduction.

Natural Coagulants: Researchers investigated bio-based coagulants derived from plants, algae, and tree bark. A six-month trial compared traditional ferric sulphate dosing with natural coagulants at Woolton WwTW. The findings indicated that combining natural coagulants with ferric sulphate is a viable method for phosphorus removal. Notably, United Utilities has already implemented natural coagulants at sites in Cheshire as part of their AMP7 investment programme.

Reactive Media: This approach utilizes adsorptive materials that attract phosphorus to their surfaces. Southern Water and the University of Portsmouth led trials on seven new reactive materials, including cockleshell and catalytic carbon, at various sites in Hampshire and West Sussex. Some materials, particularly Phosflow pellets made from naturally occurring minerals, achieved notably low phosphorus levels.

The ALT-P project’s outcomes offer promising sustainable alternatives to traditional chemical treatments, potentially reducing environmental impact and enhancing safety in wastewater management.

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