Table 5 summarizes the amount of dissolved electrodes and
electrical energy consumption per one cubic meter of treated
wastewater and the corresponding removal efficiencies at different
current densities and EC treatment times. As expected, it is clear
that increasing current density and/or EC time increases the
removal of heavy metal ions, which is associated with increasing
both the specific electrical energy consumption and the specific
dissolution of electrodes. In order to maximize the removal efficiency
at the operating conditions of this study, the current density
must not be less than 4 mA/cm2 and EC treatment time should be
in the range of 45 to 60 min. These operating conditions minimized
the specific energy consumption to the level of 6.25–8.33 kWh/m3
and the specific amount of dissolved electrodes to the level of
1.31–1.74 kg/m3. These consumption levels were in very good
agreement with the results reported in the study of Akbal et al.
[1] in which 20 min EC treatment with current density of
10 mA/cm2 at pH = 3.0 was able to achieve removal efficiency of
100%, 100% and 99% for Cr3+, Cu2+ and Ni2+, respectively. The corresponding
energy and electrode consumptions were 10.07 kWh/m3
and 1.08 kg/m3, respectively.