磁絮凝法和高梯度磁流体萃取法集成处理含铬废水

Removal of chromium-containing wastewater by integration treatment of magnetic flocculation and HGMS magnetic-fluid extraction

将磁分离技术和化学絮凝法、溶剂萃取法相结合,提出磁絮凝法和高梯度磁流体萃取法集成处理高浓度含Cr电镀废水的新工艺。采用磁絮凝法对高浓度含Cr电镀废水进行一次处理,通过正交实验方法获得了最佳磁絮凝条件:pH 8,磁性Fe3O4颗粒用量4 g,搅拌速度80 r·min-1,主絮凝剂PAFC用量6 ml,可使废水中Cr浓度由4325.13 mg·L-1降为29.8 mg·L-1;采用高梯度磁流体萃取法对磁絮凝后废水进行二次处理,将该废水流经两个串联的高梯度磁流体萃取装置,持续动态萃取7 h,在最佳萃取条件下,最高萃取率为99.40%,平均萃取率98.97%,总萃余液Cr浓度由29.8 mg·L-1降为0.31 mg·L-1,低于国家排放标准;碱性条件下磁流体萃取剂反萃率大于90%,再生磁流体萃取剂可重复使用。

The magnetic separation technology was combined with chemical flocculation and solvent extraction method to synthetically provide a new way of treating chromium-containing wastewater by the application of magnetic flocculation and high gradient magnetic separation(HGMS)for magnetic-fluids extraction.Namely magnetic flocculation method was used to treat high concentration chromium-containing electroplating wastewater once,and the optimal magnetic flocculation conditions were obtained by orthogonal test method:pH 8,the dosage of magnetic Fe3O4 particles 4 g,mixing speed 80 r·min^-1,the main flocculant PAFC dosage 6 ml,under which can reduce the chromium concentration in the wastewater from 4325.13 mg·L^-1 to 29.8·mg·L^-1.After magnetic flocculation treatment,the method of high gradient magnetic-fluids extraction was used in secondary processing,the wastewater was pumped and continuously flowed through two series of high gradient magnetic-fluids extraction devices within seven hours,and the highest extraction rate could achieve 99.4%,average extraction rate could achieve 98.97%,under optimal conditions.Furthermore,chromium concentration could be reduced to 0.31 mg·L^-1,which met the national emission standard.Under alkaline conditions,the stripping rate of magnetic fluid was more than 90%,and the regenerated magnetic fluid extraction agent can be reused.