Practical Considerations for Electrokinetic-Biocementation Using Carbonic Anhydrase-Producing Bacteria: Field Set Ups and Environmental Sustainability Assessment

This scoping study assesses practical aspects of electrokinetic (EK) biocementation of clay soil underneath a railway embankment ahead of upscaled testing to include a reduced-scale field pilot as an intermediate step towards subsequent pilot embankment treatment. It considers suitable field setups and performs Life Cycle Analysis (LCA) of biocementation by biostimulation of carbonic anhydrase (CA)-producing bacteria compared to hydrated lime slurry, if both treatments were implemented electrokinetically. LCA analysis was conducted using SimaPro software (version 9.6.0.1) with Ecoinvent database and bench-scale laboratory testing data. Electroosmotic flow modelling was performed to instruct on suitable setups and for estimates of power consumption towards the field application of 30 m of railway embankment and foundation soil. LCA indicated a considerable reduction in global warming if CA biocementation is used (0.00823 kg CO2 eq for biocement vs. 0.022136 kg CO2 eq for lime), and resource usage (7.06 × 10−5 kg Cu eq compared to 8.47 × 10−5 kg Cu eq for lime). Biocementation was more water-consuming compared to lime, as it involved multiple chemical solutions. Terrestrial acidification, aquatic eutrophication, and ecotoxicity were slightly higher for biocement, possibly due to system boundaries and processes assumed for material production. Further sustainability improvements would be possible if waste materials (e.g., captured industrial CO2) could be used. Field trials will be essential for validation, system optimisation, and advanced model calibration.