Screening Life-Cycle Carbon Assessment of Greywater Electrocoagulation: Effects of Applied Current, Electricity Carbon Intensity, and Electrode Production Route

Electrocoagulation (EC) can reduce the organic load of greywater, but increasing treatment intensity may shift environmental burdens toward electricity use and sacrificial-electrode production. This study integrated bench-scale experiments with a screening life-cycle carbon assessment to evaluate aluminum (Al) and iron (Fe) electrodes at applied currents of 0.1, 0.2, and 0.3 A. COD removal, electrolysis energy consumption, and theoretical electrode consumption were evaluated, with climate-change impacts expressed per cubic meter of treated greywater and per kilogram of COD removed. Applied current significantly affected COD removal (p < 0.001), whereas the overall effect of electrode material was not significant. Mean COD removal increased from 68.0 to 95.8% for Al and from 62.0 to 96.2% for Fe between 0.1 and 0.3 A, while specific energy consumption increased from 0.45 to 3.00 and 3.15 kWh/m3, respectively. Under the reference life-cycle scenario, total global warming potential increased from 0.46 to 2.16 kg CO2e/m3 for Al and from 0.33 to 1.83 kg CO2e/m3 for Fe. Lower-current operation also produced the lowest impact per kilogram of COD removed. Contribution analysis revealed a shift in environmental hotspots: primary-Al production dominated at 0.1 A, whereas electricity dominated Al at higher currents and Fe under all tested currents. Electricity-carbon-intensity and electrode-production-route scenarios showed that decarbonized electricity substantially reduced impacts at high current, while low-carbon Al and scrap-based steel became increasingly important as electricity-related impacts declined. The results demonstrate that the climate performance of greywater EC depends jointly on treatment target, applied current, electricity supply, and electrode production pathway. The assessment provides early-stage decision support for lower-carbon and more circular EC design but should be validated through pilot-scale operation and an expanded multi-impact life-cycle inventory.