ELECTROLYTIC DENITRIFICATION - LONG-TERM PERFORMANCE AND EFFECT OF CURRENT INTENSITY

The long-term performance of the biofilm-electrode reactor is demonstr ated for denitrification. The total nitrate and nitrite concentration, oxidation-reduction potential (ORP), total organic carbon (TOC), colo r, and viable cell. count in the effluent, were monitored to evaluate the performance of the reactor. Initially, the applied electric curren t intensity was varied from 0 to 100 mA. A nitrate removal efficiency exceeding 98% was achieved at a current of 20 mA when phosphate was us ed as a buffer. Current intensities between 20 to 25 mA resulted in th e lowest effluent concentrations of nitrate, whereas, lower current in tensities affected proportionately less nitrate reduction. Fnr higher current intensities, hydrogen inhibition and charge induced repulsion caused decreased reduction efficiencies. ORP was governed by both the concentrations of hydrogen and effluent nitrate. A total nitrate remov al efficiency of 85% was achieved at a current level of 25 mA in the a bsence of any nutrient. No appreciable change occurred in viable cell count in the effluent with time. (C) 1998 Elsevier Science Ltd. All ri ghts reserved.