混凝沉淀法处理工业含氟废水的工艺研究

以半导体工业中的含氟废水为研究对象,采用混凝沉淀法对去除废水中氟离子进行了系统的工艺研究.以Ca(OH)2为沉淀剂,分别用聚合氯化铁(PFC)和聚合氯化铝(PAC)为混凝剂,并加入聚丙烯酰胺(PAM)助凝剂的方法,对药剂投加量、混凝剂种类、体系pH值、沉降时间等因素进行了实验探索.结果显示,PFC比PAC混凝效果好.当Ca(OH)2添加量为理论值的2.5倍,PFC用量为15mg/L,助凝剂PAM用量为4mg/L,体系的pH值在6～7时,其除氟效果最佳,此时废水中残留氟离子浓度可降低至5.5mg/L,远远低于国家规定的排放标准(10mg/L).

Coagulating Process for Treatment of Fluoride-Containing Industrial Wastewater

The coagulating process for removal of F-ions in semiconductor industrial wastewater was investigated systematically by using lime as precipitating agent,poly ferric chlorine （PFC） and poly alumina chlorine （PAC） as coagulants,and polyacrylamide （PAM） as flocculant.The effects of dosage of additive,type of coagulants,pH,and settling time on removal efficiency of F-ions were explored.Results show that coagulant PFC possesses better performance than coagulant PAC.The highest removal rate of F-ions is obtained when the dosage of Ca（OH）2 is 2.5 times of the theoretical value,the dosages of coagulant PFC and flocculant PAM are 15 mg/L and 4 mg/L,and pH of the system is 6～7.The concentration of residual F-ions in the treated wastewater is as small as 5.5 mg/L,much lower than 10 mg/L specified in relevant national standard for discharge.