This study investigated the adsorption of PO43- onto encapsulated nanoscale zero-valent iron (nZVI). At initial PO43-: 10 mg center dot L-1, the optimum condition was initial pH: 6.5, nZVI dosage: 20 g center dot L-1, stirring-rate: 100 rpm, and time: 30 min, achieving PO43- removal of 42%. The effect of pH and time on the PO43- removal efficiency was quadratic-linear concave up, whereas the curve of nZVI dosage was quadratic-convex. Artificial neural network with a structure of 5-7-1 adequately predicted PO43- removal (R-2: 97.6%), and the sensitivity analysis demonstrated that pH was the most influential input. The cost of the adsorption unit was 3.15 $USD center dot m(-3).