Basic study about nitrate removal by electrolysis

In this process hydrogen was produced by electrolysis of water. To maintain a low dissolved oxygen concentration in the solution, carbon electrode was sed as the anode. Supplying microorganisms to the reactor is unnecessary for this process, because denitrifying organisms naturally occur in the reactor. The applied electric current was in the range of 5 mA to 100 mA. The initial nit ate solution used in this study was about 20mgN * l ^ - 1 , prepared by dissolving KNO; in the tap water, and no nutrition was added. The denitrification rate increased with the increase of electric current. However, nitrite as intermediate product, remained when the amount of hydrogen supplied is insufficient. This could be reduced by rising the electric current for feeding enough hydrogens. In the case of 100 mA of electric current, denitrification rate was 8.3mg - N * l ^ - 1 h ^ - 1 and nitrite remaining was less than 0.4mg - N * l ^ - 1 The hydrogen utilization efficiency decreased with the increase of the electric current, because hydrogen solubility in water is very low (1.6mg * l ^ - 1) The maximum hydrogen utilization efficiency was 76% when the electric current was 5 mA. The maximum energy consumption in this process was around 0.05 sim0.6 Wh * g ^ - 1 - N. This denitrification method is a safe, cheap and extensive method to remove nitrate from drinking water and easy to control the hydrogen flow rate by changing the electric current