By Dr Dana Ofiteru, Newcastle University
Access to a continuous flow of untreated municipal wastewater at the BEWISe pilot plant enabled the first systematic feasibility study of bacteria-based self-healing (BBSH) concrete under realistic wastewater conditions.
Portland-cement concrete contributes about 8 % of anthropogenic CO2 emissions and, in wastewater treatment plants and sewers, undergoes (bio)chemical corrosion that drives considerable maintenance expenditure – estimated at ~£85 million per year in the United Kingdom. Improving durability of concrete has therefore implications both for lowering emissions and reducing the costs for water companies.
Supported by funding from UKRI-EPSRC and an Impact Acceleration Account, we used mortar prisms containing environmental bacterial-spores alongside uninoculated controls and immersed them in the BEWISe wastewater stream while identical specimens were tested in tap water (Fig 1).
Over several months the inoculated mortars exhibited reproducible crack closure through bacteria-mediated calcium carbonate precipitation. When supplementary calcium and carbon sources were incorporated, comparable healing occurred in uninoculated specimens, indicating that the resident wastewater microbiome can supply the required activity (Fig 2). A twelve-month re-cracking trial confirmed retention of the healing capacity.
These findings underpin an ongoing Knowledge Transfer Partnership with Northumbrian Water that will evaluate the embedding of these research in Northumbrian Water and charting a practical route toward longer-lasting, lower-carbon wastewater infrastructure.
