Technological conditions and process analysis on denitrification of biofilm-electrode system

In order to acquire biofilm-electrode with good denitrification ability, biofilm-electrodes were obtained on graphite plates by continuous and batch culture methods with activated sludge, respectively. The influences of C/N ratio, current intensity and pH value on the denitrification process were evaluated. The results indicated that the denitrification rate was in direct proportion to the C/N ratio when the ratio of C/N was less than 3.0, while the increasing rate of denitrification was slowed down when the ratio of C/N was above 3.0. A maximum value of 9.26 mg/(L·h) for nitrate removal efficiency was gotten when a current intensity of 20 mA was applied. With larger amounts of current density, the nitrate removal efficiency was decreased. A nitrate removal loading of 7.89 mg/(g·h) was obtained when pH was at 7, but the denitrification ability of biofilm-electrodes was decreased with the pH value above or below 7. A comparison of denitrification with methods of electrolysis, biofilm and biofilm-electrode was carried out and a cooperation evidence of electrode process and biofilm was proved.