United Utilities has become the first water company in the UK to adopt an innovative plant-based natural coagulant method of phosphorus removal.

Excess phosphorus remains the most common cause of water quality failure in England and Wales, with ever-tightening regulatory targets driving investment in 2025-30. UK water companies currently spend in the region of £39 million a year on metal-based chemicals to remove phosphorus, with demand and prices rising.

Chemical processes pose a particular challenge for small, rural sites, which have higher relative investment needs for phosphorus removal and limitations in terms of site footprint, transport logistics and community impact.

Earlier this year the North West water company was the lead partner in a nationwide project to put alternative methods of phosphorus removal to the test. Backed by Ofwat’s Water Breakthrough Challenge, researchers examined three alternative phosphorus removal methods – electrocoagulation, natural coagulation and reactive media. A range of different technologies from various providers were explored in lab tests and onsite trials.

Now, following a successful six-month on-site trial in a test lane at their Woolton Wastewater Treatment Works in Merseyside, United Utilities is introducing a method which uses a natural coagulant created from tree bark at some of its small rural wastewater treatment facilities across the North West.

United Utilities’ Principal Engineer (Innovation), Callum Grundy, explained the importance of the project saying:

“We are exploring a range of different technologies and methods that enhance phosphorus removal and reduce reliance on chemical dosing. This trial has delivered fantastic outcomes, and we are incredibly excited that we are now introducing solutions based on natural coagulants more widely across our region.

“The extensive research means we now understand the capacity for phosphorus removal, the ideal site characteristics and how best to implement them."

Following the trial, United Utilities is working closely with provider Veolia Water Technologies to fast-track the introduction of the product.

Brian Jones from Veolia Water Technologies commented:

“Our Hydrex range of plant-based products are already used in the food and beverage industry to provide water clarification.

“The trial has demonstrated that introducing a Hydrex plant-based coagulant has proved to be very effective in settling out suspended solids and colloidal matter from wastewater and this has resulted in significant reductions of excess iron and phosphorus in the final effluent."

Callum Grundy added: “Innovative approaches such as this support the water sector’s drive to embed more sustainable treatment processes. They help us increase resilience, deliver financial and carbon savings and help maintain compliance, which will ultimately mean a cleaner environment.”

The adoption of this method follows United Utilities’ adoption of the FujiClean CRX system. Earlier this year the company became the first in Europe to adopt the system which is particularly suited for sites that have previously used septic tanks.