Electrochemically-assisted ammonia recovery from wastewater using a floating electrode

A novel methodology for the removal and recovery of NH₃ from wastewater based upon electrochemical oxidation and a previously unreported electrochemically-assisted surface transfer mechanism is introduced. Recovery of NH₃ is done by placing a porous cathodic electrode at the wastewater-air interface wherein the cathode creates local alkalinity and an electric field that draws ammonium ions towards the wastewater-air interface resulting in near-linear reductions of dissolved ammonium irrespective of concentration. This methodology resulted in great NH₃ recovery without the need for ion-exchange membranes. Also anodic reactions that simultaneously occur at depth in the wastewater induced NH₃ oxidation in accordance with proven mechanisms. The floating electrode approach offers improved NH₃ removal efficiency in comparison to electrooxidation. Trials conducted on synthetic wastewater and filtered anaerobic centrate demonstrated decreased NH₃ concentration up to 216 mg/l-hr and 110 mg/l-hr respectively under 5 mA/cm² current density. The technology would be best used to treat municipal and industrial wastewaters possessing high NH₃ concentration.