Study On The Treatment Of Water Containing Humic Acid By Electro-Coagulation

Humic substance is the main organic composition in surface water, which can transfers to DBPs such as THMs in disinfection. DBPs are harmful to people's health. Humic acid can also affect the result of coagulation, make water colourful, cause some illness and so on. So we should pay more attention on the removal of humic acid.The solution containing humic acid compounded in lab and the groundwater from Songhua River have been studied in electro-coagulation process to remove humic acid. I have investigated the choosing of electrode material and the effect of many factors in electro-coagulation, such as current density, initial concentration of humic acid, initial pH, dosage of electrolyte and so on. Then I compared the treatment effect of electro-coagulation with that of traditional coagulation. By the means of analysis of the forms of Al³⁺, I have researched on the effect of Ala, Alb and Alc in the electro-coagulation process. I have also calculated the efficiency of current to produce Al³⁺, and determined which factor affects it most.The removal of humic acid with Al electrode is better than that with Fe electrode obviously. With the data, we can also come to the conclusion that: initial concentration of humic acid play the most important role in the electro-coagulation process. Current density, which also affects the power consuming, is another significant factor in the treatment. The removal ratios of humic acid with different initial pH are nearly the same. The concentration of the electrolyte has no effect on the removal, but it's a very important factor on power consuming. Temperature has very little effect in the electro-coagulation process. According to the composition analysis of Al³⁺, I infer that Alc plays the most significant role in electro- coagulation, and Alb the second place. Ala makes a very little effect in this process. When the concentration of OH- grows, Ala can transfer to Alb and Alc. Prolonging the reaction time and increasing the current density can make the efficiency of current to produce Al³⁺ lower, while initial pH has little effect on efficiency of current.