Method for treating alkaline fluorine-containing wastewater by combining induced crystallization method with tubular membrane filter

A method for treating alkaline fluorine-containing wastewater by combining an induced crystallization method with a tubular membrane filter (TMF), comprising:

• step 1, introducing fluorine-containing wastewater into a regulating pond, and regulating a potential of hydrogen (pH) of the fluorine-containing wastewater to a range of 8.0-8.5 to obtain the alkaline fluorine-containing wastewater;
• step 2, introducing the alkaline fluorine-containing wastewater from the regulating pond into a first-stage chemical sedimentation tank, adding calcium chloride, poly aluminum chloride, calcium fluoride, and tremolite into the first-stage chemical sedimentation tank sequentially in that order to obtain first-stage fluorine-containing wastewater, performing shearing treatment on the first-stage fluorine-containing wastewater by using a high-speed shearing machine to obtain sheared first-stage fluorine-containing wastewater, introducing the sheared first-stage fluorine-containing wastewater into a first-stage coagulation sedimentation tank to obtain first-stage coagulating-sedimentation wastewater, and then introducing the first-stage coagulating-sedimentation wastewater into a first-stage inclined-tube sedimentation tank to discharge a first-stage effluent;
• wherein a dosage of the calcium fluoride is in a range of 120-150 milligrams per liter (mg/L), and a dosage of the tremolite is in a range of 6-10% of the dosage of the calcium fluoride;
• and a shearing rate of the high-speed shearing machine is in a range of 5,400-5,600 revolutions per minute (r/min);
• step 3, introducing the first-stage effluent into a second-stage chemical sedimentation tank, adding calcium chloride and poly aluminum chloride into the second-stage chemical sedimentation tank sequentially in that order to obtain second-stage wastewater, stirring the second-stage wastewater to react to obtain reacted second-stage wastewater, introducing the reacted second-stage wastewater into a second-stage coagulation sedimentation tank, adding polyacrylamide into the second-stage coagulation sedimentation tank to obtain second-stage coagulating-sedimentation wastewater, and then flowing the second-stage coagulating-sedimentation wastewater into a second-stage inclined-tube sedimentation tank, and discharging a second-stage effluent through the second-stage inclined-tube sedimentation tank;
• and
• step 4, performing a treatment on the second-stage effluent by using the TMF to obtain treated second-stage effluent, and then discharging the treated second-stage effluent.