Development of denitrification method with hydrogen gas as an electron donor

Two types of laboratory-scale continuous autotrophic denitrification using hydrogen gas as an electron donor were studied at 25 ℃, and the effect of feed solution rate on the denitrification rate and hydrogen utilization efficiency was investigated. In the experiment using hydrogen gas supplied from the gas tank, at each feed solution rate,high nitrate removal rate was achieved. However, high concentration of nitrite in the effluent was detected and the efficiency of hydrogen utilization was remarkably low. In the experiment using polypropylene sponge as packing material, the denitrification rate was highest. In the case hydrogen gas was dissolved in the separate column before
supplying to the column, the maximum denitrification rate was 60%. In the experiment using hydrogen generated from the electrolysis of water, with polypropylene sponge as packing material and anode and cathode were placed separately, nitrate was removed until 1 mg-N . /1 and nitrite was almost completely suppressed. Comparing with the method using hydrogen supplied from a gas tank, the method using hydrogen generated from the electrolysis of water is easy to control, high hydrogen utilization efficiency and RPPT low cost.