Investigation of electrocoagulation with hydroxide-activated aluminum‑copper (Al/Cu) internal micro-electrolysis system for aquaculture, dye, and antibiotic wastewater treatment

Abstract

The increasing expansion of aquaculture, combined with the extensive use of synthetic dyes and antibiotics in industrial activities, has led to severe contamination of coastal ecosystems and significant risks to human health. This study evaluates the performance of a hydroxide-activated aluminum‑copper (Al/Cu) internal micro-electrolysis (IME) system for treating aquaculture wastewater contaminated with Rhodamine B (RhB) and ciprofloxacin (CIP). The IME process utilized aluminum and copper electrodes in the effluent, and key operational parameters NaOH dosage, pH, reaction time, stirring, and oxygen bubbling were optimized to maximize pollutant removal. The system effectively reduced total solids, suspended solids, dissolved oxygen, nitrite, nitrate, ammonia, RhB, and CIP. Hydroxide activation increases electrode reactivity to organic compound waste. The system achieved removal efficiencies of 58 % for CIP, 62 % for RhB, and over 78 % for aquaculture-related pollutants. Analytical techniques such as SEM-EDX and XRD confirmed the presence of aluminum and aluminum hydroxide on electrode surfaces, while FTIR spectra demonstrated the formation of AlO bonds. Pollutant removal was attributed to flocculation with Langmuir isotherm adsorption (q_m = 2.43 mg/g, ΔG = −2.59 kJ/mol) and oxidative degradation resulting in the adequate mineralization of RhB and CIP intermediates. These findings highlight the potential of the IME system as an efficient, cost-effective, and scalable solution for complex wastewater treatment.