Electro-thermal treatment of high concentration ammonia in water by gaseous oxidation in liquid phase (GOLP)

Gaseous oxidation in liquid phase (GOLP) process was proposed to degrade high concentration ammonium in water. The innovative concept behind the reactor design is that the monocrystalline silicon chip coated with catalyst could be heated instantaneously by direct current, which will gasify the surrounding ammonium solution and later catalytically convert it to harmless N2. It is found out that Co3O4 instead of Co2O3 is the active catalytic component in the GOLP process and it coats the silicon chip evenly with nut-shell particle. The experimental results reveal that the GOLP process could degrade high concentration NH4+ efficiently, in which when the current was 10 A, the reactor could remove almost 98% NH4+ after 2 h treatment, at the initial concentration 1810 mg L−1. The overall GOLP process for de-nitrification could be presumed to have two steps: (1) the gasification of liquid around catalyst; and (2) catalytic conversion of NH4+ to N2, which is experimentally demonstrated by Ion Chromatography data. Also, the influences of current and pH were investigated to optimize the operating parameters for the GOLP reactor, and the preliminary energy consumption analysis based on lab data was provided for future reference. These results show that the GOLP process will be able to sustain without extra energy input theoretically if the ammonia concentration is higher than 1.48%.