基于两级强化化学混凝沉淀法的低浓度含氟工业废水深度除氟研究

Deep Fluoride Removal from Fluoridated Industrial Wastewater based on Two-stage Enhanced Chemical Coagulation and Precipitation Method

针对低浓度含氟工业废水处理厂深度除氟至1.5 mg/L的需求,充分利用CaCl_(2)和废水处理厂内PAC、PAM等常规混凝剂及投加设施,考察在废水处理工艺流程的前端与尾端分别采用化学沉淀法除氟、一级/两级化学絮凝沉淀法除氟的效能。结果表明:化学沉淀法不适合处理低浓度含氟废水,投加200 mg/LCaCl_(2)仅能将[F-]由10 mg/L降至6.8 mg/L;一级化学混凝沉淀法采用120 mg/LCaCl_(2)+600 mg/L PAC+3 mg/L PAM组合投加,能将[F-]由10 mg/L降至3.8 mg/L;两级化学混凝沉淀工艺的除氟效率明显优于一级,将120 mg/L CaCl_(2)+600 mg/L PAC+3 mg/L PAM按1:1分两段投加时,能将[F-]由10 mg/L降至1.38 mg/L,可达到深度除氟的目标浓度1.5 mg/L。研究可为含氟工业废水处理项目提供深度除氟工艺设计参考。

To address the demand for deep fluoride removal to 1.5 mg/L in industrial wastewater plants containing fluoride,the performance of deep fluoride removal by chemical precipitation method or primary/two-stage chemical flocculation and precipitation method at the front and tail end of the wastewater plant process was investigated by making full use of CaCl_(2) and conventional coagulants and dosing facilities such as PAC and PAM in the wastewater plant.The results showed that the chemical precipitation method was not suitable for treating low concentration fluoride wastewater,and the application of 200 mg/L CaCl_(2) could only reduce[F-]from 10 mg/L to 6.8 mg/L.The primary chemical coagulation and precipitation method,using a combination of 120 mg/L CaCl_(2)+600 mg/L PAC+3 mg/L PAM,could reduce[F-]from 10 mg/L to 3.8 mg/L.The fluoride removal efficiency of the secondary chemical coagulation and precipitation process was significantly better than that of the primary process.The study can provide a reference for the design of process routes for deep fluoride removal in industrial wastewater plants.