单晶硅生产废水处理工程实例

Engineering project of wastewater treatment in monocrystalline silicon production

银川经济开发区某基地单晶硅生产过程中产生大量的原料清洗废水、机加废水、插片机废水、金刚线切割液废水、综合废水等多种废水。这些废水中含有大量硅粉和难降解有机物,可生化性差。针对该生产废水特点,采用多种废水分类收集、单独处理的形式。原料清洗废水经两级混凝沉淀工艺去除氟离子;机加废水采用混凝沉淀、混凝气浮两级工艺进行固液分离;插片机废水采用混凝气浮的预处理工艺进行固液分离,然后与综合废水混合处理;金刚线切割液经两级板框压滤机脱水后,压滤液与综合废水混合处理;综合废水采用混凝气浮、水解酸化、沉淀、好氧、MBR的处理工艺;污泥经板框压滤机脱水后外运,出水水质达到《污水综合排放标准》(GB 8978—1996)—级标准要求。

A large number of wastewater,including raw material cleaning wastewater,machine processing wastewater,chip inserting machine wastewater,diamond wire cutting fluid wastewater,comprehensive wastewater and so on,was generated during the production of monocrystalline silicon in a base of Yinchuan Economic Development Zone,which contained a large amount of silicon powder and refractory organic matter,and the biodegradability was poor.Wastewater was collected by classification and treated separately according to its characteristics.The raw material cleaning wastewater was treated by the two-stage coagulation sedimentation process to remove fluorine i-ons;The machine processing wastewater was treated by the two-stage process of coagulation sedimentation and coagulation air flotation for solid-liquid separation;The chip inserting machine wastewater was treated by the pretreatment process of coagulation and air flotation for solid-liquid separation,and then mixed with the comprehensive wastewater for treatment;The diamond wire cutting fluid was dehydrated by two-stage plate and frame filter press,and the press filtrate was mixed with comprehensive wastewater for treatment;The comprehensive wastewater was treated by the combination process of coagulation air flotation,hydrolysis acidification,sedimentation,aerobic and MBR;The sludge was dewatered by the plate and frame filter press and then transported out.The operation practice proved that the effluent quality meets the first-class standard of the Integrated wastewater discharge standard(GB 8978-1996).