3.4. Effect of initial pHIn the ele

3.4. Effect of initial pH
In the electrocoagulation process, pH of the solution is known to play an important role [14].To examine its effect,
the initial pH is adjusted to 3.9, 5.8, 6.7, 7.5 and 10.1. Removal efficiencies of COD and NH3-N are presented in
Fig.5 with constant operating time of 30 min and current density of 2.98 mA/cm2. The maximum removal of COD
and NH3-N were observed at initial pH 6.7 and 7.5, and the efficiencies of COD and NH3-N were 35.3% and
25.3%.The drop of removal efficiency occurred when pH tends towards acidic or basic values. When the initial pH
is increased from 3.9 to 7.1, the effluent pH increased from 5.9 to 7.8, and the influent pH is lower than the initial
pH when the initial pH is greater than 7.1. The pH could be increased by the hydrogen generation at the
electrocoagulation cathodes and the liberation of hydroxide ions from iron hydroxide[15]. To take into account the
raw water pH