Optimization of Aluminum Electrocoagulation Parameters for Nutrient Removal from Hydroponic Wastewater Using Response Surface Methodology

Abstract

Hydroponic systems represent a sustainable, soil-less alternative to conventional agriculture, offering high water-use efficiency and reduced land demand. However, the resulting hydroponic wastewater solution (HWS) requires proper treatment to prevent environmental contamination and enable nutrient recovery. This study systematically optimized the electrocoagulation (EC) process for nitrate and phosphate removal from HWS using Response Surface Methodology (RSM) based on the Box–Behnken Design (BBD). The effects of three key factors—applied current (0.03–0.80 A), electrolysis time (10–60 min), and number of aluminum electrodes (2, 4, 6)—were examined to maximize nutrient removal efficiency while minimizing energy consumption. Statistical modeling in Minitab software 2021, confirmed the strong influence of these parameters on removal performance (p < 0.05, high R2 values). Phosphate removal was highly efficient, reaching 99.7% under optimal conditions (0.415 A, four-electrode configuration, 35–60 min). However, nitrate removal was low at lower levels of applied current (0.03 A), with the best performance (Greater than 95%) achieved at 0.8 A and 60 min using six electrodes. Higher current and electrode numbers improved removal efficiency, though excessive current occasionally caused electrode passivation. Energy analysis showed that increasing the current and electrode number enhanced removal efficiency but also elevated power consumption. Overall, the results demonstrate that fine-tuning current intensity and electrolysis duration is critical to balance removal performance and energy demand. The study concludes that electrocoagulation is an effective and treatment option for nutrient recovery and decentralized management of hydroponic wastewater.