Study On Electrolysis-Coagulation Pretreatment Of Dyeing Wastewater With High Concentration

Dyestuff wastewater is a kind of organic wastewater with the characteristics of complexity of organic matters,high concentration,toxicity and containing of many hardly treated matters. Because of this, the traditional biological or physical chemistry techniques can not make the wastewater clean enough to satisfy the treatment criteria at an acceptable expense. Thus, it is a difficult problem to be solved to treat the high concentrated industrial wastewater in the field of environmental protection techniques in our country. In this thesis, a research based on the dyestuff wastewater from the factory where dye materials is producted in Henan was carried out. A technical route which is Electrolysis-Coagulation Treatment was proposed. The experiments were conducted to investigate the treatment efficiencies and the influence factors, based on which the optimal operating parameters were subsequently determined.The effect of electrolytic pretreatment to dyestuff wastewater of high concentration was studied. The results demonstrated that Electro-Fenton has obvious advantages compared with Coagulation-Electroflotation and Electro-Oxidation indirectly. Keeping the distance between anode and cathode about 3 centimeters,the electrolytic voltage 15 volt,the pH value about 4, electrolyzed the wastewater about 1.5 hours. Then COD concentration removing rate approached about 44% by the function of high efficient coagulation and oxidation. Furthermore the Fe2+ remained would be beneficial to the further coagulation handling. Thus, Electro-Fenton method was used as the first step of pretreatment of dyestuff wastewater.The effect of coagulate pretreatment to the wastewater treated by Electro-Fenton was studied. The results demonstrated that lime throwed in can not only rise the pH value of the wastewater, but also react with the Fe2+. When the pH value rised to 7～8, the COD concentration of the wastewater can be removed about 28% by the function of cogulation of the Fe(OH)₂ and Fe(OH)₃ reacted. In addition, Ca2+ would react with SO₄^2- in the wastewater and the little-dissolved outcome parted deposit. Afterward, Al₂(SO₄)₃ coagulant and PAM as coagulant aid were put into the wastewater to cause cogulation reaction. And the optimal...