The range of COD in iron electrochemical process shown in figure 4.5. Because of electrochemical process did not remove insoluble COD. Change graph 3 cm can reduce COD more than 1 cm, the compare a quantity of COD by using distance. The initial of COD are approximately 800 both 1 cm and 3 cm. However, the system can reduce the COD is less than 50 percentage. So expected the electrochemical process did not remove insoluble COD.