化学沉淀-纳米吸附工艺深度处理含氟废水

Advanced treatment of fluoride wastewater by chemical precipitation&nano material adsorption

半导体生产过程中会产生大量含氟废水,传统双钙法除氟工艺对氟的去除程度有限,不能满足日益严格的废水排放标准。为满足出水低于1.5 mg/L的深度除氟要求,对化学沉淀-纳米材料吸附组合工艺深度处理半导体企业含氟废水进行了系统性研究。通过控制变量实验考察了不同初始pH、药剂量、氟浓度、上柱液pH、共存离子对除氟效果的影响,并进行中试扩大实验研究了吸附材料的再生条件以及稳定性能。结果表明,综合考虑出水氟离子浓度与药剂成本等因素,在调节反应初始pH为8.5,并投加自制铝盐为主的沉淀剂160 mg/L条件下,出水氟离子可降到3 mg/L以下。然后过滤并调节上柱液pH至3.0进行纳米材料吸附除氟,最终出水氟离子可稳定达到1.5 mg/L以下,符合《地表水环境质量标准》(GB 3838—2002)Ⅳ类标准。最后,选择质量分数高于4%的NaOH溶液作脱附剂,可实现吸附材料的再生。

A large amount of fluorine-containing wastewater is produced in the process of semiconductor production.The traditional double calcium addition treatment process has a limited degree of fluorine removal and could not meet the stricter sewage discharge standard.A combined process of chemical precipitation and nanomaterial adsorp⁃tion for advanced treatment of fluoride wastewater was systematically studied to meet the requirement of less than 1.5 mg/L of fluorine in the effluent.The effect of fluoride removal was investigated basing on different initial pH,re⁃agents dosage,fluoride concentration of precipitation process,and pH,coexisting ions in the adsorption process by control variable experiments.The regeneration conditions and stability performance of the adsorbent were studied by pilot scale-up experiments.The results showed that,considering fluoride of outlet and costs of reagents,at the initial pH of 8.5,a homemade aluminum salt was chosen as the precipitant with a dosage of 160 mg/L,thus,the fluoride of effluent could be treated below 3 mg/L.The above effluent was followed by filtering and adjusting pH to 3.0 before adsorption by special nanomaterial,and the fluoride of the effluent was,stably,less than 1.5 mg/L,which met the TypeⅣof the Environmental Quality Standard for Surface Water(GB 3838-2002).Finally,higher than 4%NaOH solution was selected as the desorbent to regenerate the adsorbent.