Study On Color Removal From Reactive Dye Wastewater By Technology Of Magnesium Blended Coagulation

Dye wastewater treatment is one of the most key issues in environmental engineering. When magnesium salts were used as coagulants in chemical coagulation treatment, various researchers found that magnesium and other coagulants were blended to treat wastewater could gain better teratment efficiency under the less coagulants dosages added, which was called synergistic effect, and it is still lacked depth study.Aiming at reactive dye wastewater, which is the great mass of industrial dye wastes, the study on color removal from simulation KN-B reactive dye wastewater (concentration of 80mg/L) by technology of magnesium blended coagulation is proposed in this thesis. The experiment is devised in the following steps:(1)Commonly used four inorganic coagulants(FeSO₄, Fe₂(SO₄)₃, Al_SO43, MgSO₄) are selected and used to treat model reactive dye wastewater in this study. Optimal treatment conditions of four single coagulants under the fixed whisking condition are investigated and mechanisms of color removal treatment are analyzed. The decoloring rate reaches 95.1% under the appropriate conditions of pH 12.36, the FeSO₄ dosage of 1640mg/L and deposited 20min. The decoloring rate reaches 93.44% under the appropriate conditions of pH 10.5, the Fe₂(SO₄)₃ dosage of 290.5mg/L and deposited 3 h. The decoloring rate reaches 96.1% under the appropriate conditions of pH 11.06, the Al₂(SO₄)₃ dosage of 240mg/L and deposited 3 h. The decoloring rate reaches 97.1% under the appropriate conditions of pH 12.1, the MgSO₄ dosage of 1200mg/L and deposited 60min. Although iron salts and aluminium salts can get well color removal, they also bring side-effect. Magnesium salts not only can get well color removal, but also are safer coagulants.(2)Optimal treatment conditions of three magnesium blending coagulants under the fixed whisking condition are investigated. As experiments showed, The decoloring rate reaches 98.44% under the appropriate conditions of pH 11.1, the Mg/Fe²⁺ blengding coagulant dosage of MgSO₄ 180mg/L, FeSO₄ 71.07mg/L ,...