The effects of direct electric current on the metabolism of nitrifying bacteria

The nitrification efficiency and population dynamic of nitrifying bacteria in liquid culture and biofilm under series of direct electric current were experimentally investigated.The results indicated that the electric current less than 2.5?A·m -2 had no effect on the cells in liquid,but if the electric current was more than 5?A·m -2 the nitrification efficiency decreased.Biofilm could stand even higher current,when the current increased up to 15?A·m -2 ,the nitrification efficiency only decreased 20%.In addition,the current also greatly affected the population dynamics of nitrifying biofilm.When the current was 15?A·m -2 ,the biomass on the cathode,anode and packing decreased about 90%,58% and 8% respectively.The LP/dry biofilm weight increased when the current was high.