Optimization of hole morphology in perforated aluminum electrodes for continuous-flow electrocoagulation of industrial laundry wastewater

Industrial laundry wastewater contains surfactants, suspended solids, phosphate, oil–grease, and refractory organic matter, requiring compact treatment with stable hydraulic and electrochemical performance. This study investigated aperture morphology as an independent design variable for perforated aluminum electrodes in a continuous-flow electrocoagulation reactor at a fixed nominal open-area ratio of approximately 25%. Five perforated morphologies–circular holes, square holes, longitudinal elliptical holes, transverse elliptical holes, and 45° oblique rounded slots–were compared with a flat-electrode reference. Residence-time distribution analysis, CFD-based gas–liquid–coagulant interpretation for all morphologies, pollutant-removal tests, voltage-rise monitoring, specific energy consumption, operating-cost estimation, and MCDA were integrated to evaluate treatment and operability. The oblique rounded-slot electrode (OS-45) provided the most balanced system-level performance, with a mean residence time of 6.93 min, dead-zone fraction of 4.2%, coagulant-distribution uniformity index of 0.88, COD removal of 86.2%, turbidity removal of 93.8%, MBAS removal of 81.5%, phosphate removal of 80.4%, total SEC of 1.18 kWh/m³, and operating cost of 0.229 USD/m³. These results demonstrate that aperture orientation and rounded-edge geometry improve hydraulic renewal, coagulant utilization, voltage stability, energy efficiency, and lifecycle performance beyond the effect of open area alone.