Enhanced phosphate removal from piggery wastewater using electrocoagulation and RSM optimization for eutrophication control

Abstract Phosphorus-rich wastewater from pig farming poses a major threat to aquatic ecosystems due to its contribution to eutrophication. This study investigated the removal of phosphate from actual piggery wastewater using electrocoagulation, aiming to optimize operational parameters for maximum treatment efficiency. A Central Composite Design (CCD) under Response Surface Methodology (RSM) was employed to evaluate the combined effects of pH, current intensity, and reaction time on phosphate removal. Experimental results revealed that pH played the most crucial role, significantly influencing the hydrolysis of aluminum, which is essential for effective phosphate adsorption and co-precipitation. Current intensity and reaction time also supported the process but were less dominant. The quadratic regression model showed a strong fit (F = 112.79, p < 0.0001) with excellent predictive capability. Optimal conditions were determined at pH 8, a current of approximately 3 A, and a reaction time of 25 minutes, achieving a predicted phosphate removal efficiency of 96.47%, which was subsequently validated by repeated experiments. Further tests indicated that maintaining reaction times between 20 minutes ensured near-complete phosphate removal while minimizing energy consumption. This research provides a solid scientific basis for implementing electrocoagulation as a cost-effective and sustainable solution to manage nutrient-rich wastewater from intensive pig farming in Vietnam.