[Preliminary research on a new method of NO3- -N wastewater treatment based on electrochemistry]

A new method based on electrochemistry was presented to treat NO3- -N wastewater by analyzing theories of Pd-Me bimetal catalytic reduction of NO3- -N and NH4+ -N break point chlorination process. Presented method mainly includes following characteristics. Firstly, NO3- -N can be catalytically reduced in electric field while Ti substrate cathode was modified by common metallic elements which have empty electronic track. Secondly, NO3- -N reduction product can be controlled mainly is NH4+ -N by adjusting ratio of catalytic elements and electrolysis conditions. Finally, NH4+ -N is oxidized to harmless product N2-N by HOCl which produced from Cl- by anode oxidation process. Experiments were carried out to verified upwards theoretical assumptions. It's indicated that cathode modified by metal elements of Co and Cu can catalytic reduce NO3- -N in simulated wastewater effectively, as well as reduction product mainly was NH4+ -N while the molar ratio of Co and Cu in cathode precursor solution was 1:1. If Cl- was added to electrolysis system, NH4+ -N produced from NO3- -N reduction could be oxidized to N2-N by the anode action. Under the conditions of plate distance of 6mm, electric current of 400 mA and electrolysis time of 2.5 h, the concentration of NO3- -N, NO2- -N, NH4+ -N, and TN of simulated wastewater which initially contain 100 mg/L NO3- -N and 1000 mg/L Cl- decreased to 2.9 mg/L, 0.5 mg/L, 1.7 mg/L and 6.0 mg/L respectively.