This study aimed to determine the influence of the electric current density on the rate of nitrogen compounds removal (r_N) and the specific rate of denitrification (r_D) in a rotating electrochemical disk contractor (RECDC) and a rotating electro-biological disk contactor (REBDC). In REBDC and RECDC, the cathode consisted of disks with immobilized biomass and disk, from which biofilm was periodically removed, respectively. An aluminum anode was mounted in contactor chambers. The study was conducted using synthetic wastewater with characteristics similar to wastewater from soilless cultivation of tomatoes. The first stage of the study determined r_N and r_D in the RECDC. The second stage determined r_N and r_D in the REBDC. Four hydraulic retention times (HRT) were tested: 4 h, 8 h, 12 h, and 24 h, with electric current densities of 0.63 A/m², 1.25 A/m², 2.50 A/m², 5.00 A/m², and 10.00 A/m². In RECDC, a linear dependency was observed between r_N and current density in the examined HRTs, whereas in REBDC, a logarithmic dependency was confirmed between r_N and current density. In both contactors, an exponential dependency was observed between r_D and current density. The specific rate of denitrification decreased when the current density and HRT were increased. The study showed that, in both contactors, the rate of total nitrogen removal increased when the current density was increased and the HRT was decreased.