| In this research, completely mixed biofilm-electrode reactor (CM-BER) and compartmented biofilm-electrode reactor (C-BER) were designed and tested to remove nitrate, ammonium and organics. Effects of operation mode, parameters such as C/N ratio, current supply and hydraulic retention time were studied on the performances of CM-BER and C-BER.Firstly, we design CM-BER and choose graphite as its electrodes. The CM-BER has a good performance for the removal of nitrate (NO3--N). Effects of operating modes and parameters were tested on the removal rate of nitrate. It is shown that batch mode is more suitable for CM-BER. The best C/N ratio was about 1 and suitable hydraulic retention time (HRT) was from 4 to 7h. For 60 mA electric current supply, more than 90% of NO3--N and organics were removed in 5h when C/N ratio was 1. The average efficiency of electric current was 72% when HRT was 7h. It indicated that the removal of NO3--N was the common results of both heterotrophic and autotrophic denitrification.Secondly, based on the experience of CM-BER, C-BER was designed to remove ammonium (NH4+-N) and organics. The suitable anodic and cathodic materials are coated Ti-board and graphite, respectively. Active carbon and a small amount of ceramic granules were filled between the electrodes. Effects of temperature, pH, DO, C/N ratio, electric current supply and HRT were studied on the performances of C-BER for ammonium and organics removal. Study showed that the removal rate of total nitrogen (TN) increased with the increase of temperature. The appropriate temperature was above 20 oC. The removal rate of TN was below 10% in winter. The microorganisms at electrodes were sensitive to the change of pH value. In C-BER, nitrification decreases the pH value and denitrification increases the pH value. Under enough dissolved oxygen, the percents for organics and TN removal were 85%, 45% respectively at high C/N ratios. For lower DO, simultaneous nitrification and denitrification (SND) was...
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