Anglian Water leading Triple Carbon Reduction project

The project is aiming to create a so-called ‘triple carbon’ synergy and to this end a demonstration plant will be set up.

The core of the demonstration is an electrolyser, using renewable energy from site to split water into hydrogen and oxygen. The oxygen produced will be channelled into a novel wastewater treatment process called Membrane Aerated Biofilm Reactor (MABR), a ‘drop-in’ technology that increases the amount of wastewater that can be treated in the biological tanks that provide an environment for bacteria to digest organic waste.

MABR uses up to 75 per cent less energy compared to existing processes that bubble air into tanks where up to 70 per cent of the oxygen is wasted.

The oxygen pipe from the electrolyser will merge into process air pipework which goes to the MABR, said Giulia Pizzagalli, innovation projects manager at Anglian Water.

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“The electrolyser will produce approximately 730kg of oxygen per day, which will be oversized for our MABR. The volume of oxygen is likely to be dictated by a combination of treatment needs - maintaining effluent quality while reducing energy consumption and nitrous oxide emissions - and how much oxygen the biology in the process will be able to adapt to and sustain.

“Understanding this is one the key objectives of the trial. We have two MABR tanks running 24/7 with three membrane modules each: one tank running on air as a control and the other on progressively oxygen enriched air as a test reactor.”

Pizzagalli added that the 228kW alkaline electrolyser has been integrated into a system including pre-treatment, electrolysis, compression and storage.

The current system should produce 90kg of hydrogen every 24 hours, which Pizzagalli said is enough to fuel 30 cars.

The demonstration plant will be located at a Sludge Treatment Centre with Anaerobic Digestion facilities producing biogas.

The demonstration will use combined heat and power derived electricity from site, augmented by electricity from the grid if required.

“At the point at which we roll this out at scale, we will be looking to exploit excess electricity from our existing and planned solar assets,” said Pizzagalli.

The demonstration plant will be using potable water, but the project has a view of using treated wastewater in the future, which will need to be treated to electrolysis standard.

“As part of the Triple Carbon Reduction project, we are working with Cranfield University to investigate the required quality to meet standards and the additional treatment needs, with the aim of producing alternative, sustainable and effective treatment flowsheets for using treated wastewater for hydrogen generation,” said Pizzagalli.

The project has a completion date of June 2024 and involves Severn Trent, United Utilities, Scottish Water, Northern Ireland Water, OxyMem, Jacobs, ERM, Cranfield University, University of East Anglia, Brunel University, and two main suppliers Logan Energy and Element 2.