Proof-of-principle: Automation of a photoelectrocatalytic wastewater treatment system for the inactivation of antibiotic resistant E. coli

Intensive research has been applied to photoelectrocatalysis (PEC) for water/wastewater treatment; however, the scale-up & automation of these systems hasn't been examined. This is a critical step if PEC is to be a viable solution for water/wastewater treatment. In this work, a PEC system has been scaled up, holding a treating volume of 0.85 L in automated batch runs. Expanded titanium mesh was anodised to form titania nanotubes on the surface and was used as the photoanode with a length of 950 mm, with 3 meshes in concentric packing. The largest diameter was 28 mm giving an estimated geometric surface area of 929 cm². This work is a proof-of-principle using the charge (coulombs) passed to solution at a fixed potential to establish the required time for treatment. To ensure effective treatment, a minimum threshold current (>1.5 mA) is used for calculating the total charge, this prevents any dark current from being summed should the irradiation or power turn off, and a 1.5 factor-of-safety is also used. When the system was operated in an automated mode with the addition of 0.3 mM of peroxymonosulfate, it achieved a >5 log reduction in antibiotic resistance E. coli in synthetic wastewater.