Treatment of Super‐Intensive Pond Wastewater via Internal Electrolysis System With Fe/C Electrode Activated by Hydroxide

ABSTRACT Super‐intensive shrimp aquaculture generates effluents with elevated nitrogen species and suspended solids that exceed environmental discharge limits. In this study, a hydroxide‐activated Fe/C internal electrolysis (IE) system was developed for the treatment of super‐intensive pond wastewater. The novelty lies in the use of NaOH activation to suppress electrode passivation and sustain iron redox cycling without external energy input. Under near‐neutral conditions (pH 7–8.5), the system achieved up to 89.9% average removal of NO 2 − –N, NO 3 − –N, NH 3 –N, total suspended solids (TSS), and total dissolved solids (TDS), representing a 2–5‐fold improvement compared to conventional aeration‐based wastewater treatment plant (WWTP) performance. Electrode characterization (scanning electron microscope [SEM]–EDX, x‐ray diffractometer [XRD], x‐ray fluorescence [XRF]) confirmed dynamic formation of Fe 2 O 3 and Fe(OH) 3 phases, which functioned as in situ coagulants and catalytic redox mediators. Nitrogen removal proceeded via sequential nitrate reduction to nitrite and subsequent conversion to N 2 , coupled with adsorption and coagulation by iron hydroxide flocs. Hydroxide activation promoted a self‐regenerating passivation–corrosion cycle, ensuring sustained electrode activity. These findings demonstrate that hydroxide‐activated Fe/C IE offers a low‐cost, energy‐efficient, and scalable strategy for sustainable aquaculture wastewater management.