Abstract
An autotrophic continuous denitrification process, using hydrogen generated by electrolysis with activated carbon anodes, were experimentally demonstrated to be an effective nitrate removal process. Several fixed bed columns with polypropylene packing and honey-come shaped activated carbon anodes and stainless rod cathodes were set in thermostat chamber of 30°C, and then potassium nitrate enriched tap water, nitrogen concentration of 30mg-N·l-1, was supplied at various flow rates and electric currents. Although the anode is in the same column where microbes grow, sufficient nitrate removal was observed. For example, 94% of nitrate was removed at the HRT of as short as 1.8h for an electrical current of 6mA. A model assuming successive nitrate and nitrite reductions and plug-flow process, nitrate reduction rate=k1[NO3-][H2], and nitrite reduction rate=k2[NO2-][H2]1.5 was constructed. Calculated results with k1=1.3l·mmol-1·h-1 and k2=3.3l1.5·mmol-1.5·h-1 agreed well with the all the experimental results.
