As shown in Fig. 1(b) and (l), when the pH rises from 2.6 to 4.4, COD and color removals respectively decreases from 52.33% to 40.36% and from 53.63% to 42.49% (at reaction time of 90 min) in EF-Al. As shown in Fig. 2(b) and (l), the COD and color removal respectively decreases from 64.21% to 52.93% and from 69.39% to 54.71%, when the pH rises from 2.6 to 4.4 in EF-Fe.