A continuous ammonium removal system comprising generally an ion-exchange medium, a brine source, and an oxidative reactor. The reactor can operate with ozone as an oxidant and bromide as an oxidation catalyst. Brine recycles continuously from the reactor to the ion-exchange medium for further ammonium removal. Modular components for inline static mixing, degassing, heat exchange, flow control and electrocoagulation affect ammonium removal from waste water.