In thecoagulation process, pH of the solution affects the surface chargeof both coagulant and dye (Patel and Vashi, 2013). As can be seenin the graph, the effect of pH on the color removal is not significantwithin the selected range. However, the COD reduction efficiencyof the coagulant is highly pH-dependent and maximum COD reduc-tion could be obtained at pH 6.5 (Fig. 3b). At this optimum pH, theparticles surface charge is reduced or neutralized and the suspen-sion is destabilized.