It is well known that electrical conductivity is a key parameter
that significantly affects heavy metal ions removal from wastewater
using electrocoagulation process. This was supported by the
study of Akbal et al. [1] for the removal of copper, chromium and
nickel heavy metal ions from metal plating wastewater using EC
process. They found that the removal efficiency was strongly
increased with increasing electrical conductivity from 2 (original
wastewater) to 6 mS/cm. However in the present study, the effect
of electrical conductivity on the removal of Cr3+, Cu2+, Zn2+ and Ni2+
was not noticeable when the electrical conductivity increased from
8.9 mS/cm (original wastewater) to 12.0 mS/cm using sodium
chloride salt as shown in Table 2. This leads to the conclusion that
there is no need to adjust the electrical conductivity of metal plating
wastewater above 8.9 mS/cm in order to enhance the EC performance.
This result confirms that the contribution of electrical
conductivity on EC performance seems to be negligible at high levels
which explains the disagreement between the trend of this
study and the corresponding one reported by Akbal et al.