Removal of Soluble Phosphorus from Surface Water Using Iron (Fe–Fe) and Aluminum (Al–Al) Electrodes

Abstract

The removal of soluble phosphorus using iron and aluminum electrodes was studied in water samples from the Red River, a hyper-eutrophic stream in Winnipeg, Canada. Four trials were conducted: (I) mixed batch with 150–900 mA applied for 1 min to 1 L, (II) stagnant batch with 600–900 mA applied for 1 min to 1 L, and (III and IV) continuously stirred-tank reactor with 6.25–10 min hydraulic retention times and constant 900 mA. Maximum soluble phosphorus removals of 70–80% were observed in mixed batch, and there was no significant difference between aluminum and iron electrodes ( P value of 0.0526–0.9487). Aluminum electrodes performed significantly worse than iron electrodes under higher hydraulic loads, with iron removing >70% soluble phosphorus and aluminum <40% ( P values of 0.0035–0.0143). The estimated cost of consumables, reported per million liters of water treated, to remove 70% soluble phosphorus from eutrophic waters with 0.35 g m –3 soluble phosphorus would include 5–17.5 USD electricity costs and material costs of 5.3–12.2 USD for iron and 39.2 USD for aluminum.