Electrocoagulation–flotation treatment of industrial Pangasius processing wastewater for simultaneous COD reduction and ammoniacal nitrogen removal

Abstract Wastewater from Pangasius processing plants contains high concentrations of organic matter and nitrogen, posing challenges for conventional treatment systems. A bibliometric assessment of aquaculture‐processing wastewater studies revealed increasing interest in compact physicochemical processes and resource‐oriented treatment strategies. Guided by this trend, the present study evaluated an electrocoagulation‐flotation (ECF) reactor equipped with aluminum electrodes for the treatment of real Pangasius processing wastewater. Response surface methodology based on a Box–Behnken design was applied to examine the effects of current density (7.14–14.28 mA/cm 2 ), initial pH (7–9) and electrolysis time (20–40 min) on COD reduction and NH₄ + ‐N removal. The developed models showed high predictive performance, with R 2 values of 0.99 for COD reduction and 0.98 for NH₄ + –N removal. Under the optimized operating conditions of 33.5 min, 12.14 mA/cm 2 and pH 8.2, COD reduction and NH₄ + –N removal reached 72.62% and 63.25%, respectively. The corresponding theoretical electrode consumption was 0.64 g/L, equivalent to 0.45 kg Al/kg COD removed and 8.85 kg Al/kg NH₄ + –N removed. Principal component analysis further showed that COD reduction was mainly associated with current density and pH, whereas NH₄ + –N removal was more closely related to electrolysis time, suggesting different dominant removal pathways. These findings provide statistically supported operating conditions and practical insights for ECF treatment of fish–processing wastewater.