A Study Of Treatment Low-Concentration Fluoride Wastewater By Chemical Coagulation Precipitation-Adsorption

The fluorine is one of necessary nutritional trace element for human health.However, when water supplies contain excessive fluoride concentration, it can resultin dental or fluorosis, more severely it can cause crippling. Drinking water standardsfor fluoride does not exceed l.0mg/L in china, Sewage synthesis emission standard(GB8987-1996) of fluoride first-level emission standard is≤10mg/L.Defluorination in industrial waste water and F control in water resource becomethe most important research tasks in environment protection andsanitation fields homeand abroad. In our country, the technology of fluoride removal from low fluoridecontaining wastewater in the chemicalcombination industry has not grown up. Themain disadvantage of the technology is high equipmentcharge, high running fee anddisposal effect instability. In this paper, studying on fluoride removal by Chemicalcoagulation precipitation and adsorption,to provide a new method for fluorideremoval from low fluoride-containing.The results show that: the combination of CaCl₂ +PAC +PAM is effective wastewater treatment process for the low concentration of fluoride,on the condition ofdosing of CaCl₂ is 1200mg/L, under the condition of pH=10.5, the dosing of PAC andPAM is 400mg/L and 2mg/L, respectively, the remnant concentration of F in treatedwater is 4.6 mg/L,stable and strong loading capability and control of pH value is thekey for the process .As for the combination of CaCl₂ + Al₂(SO₄)₃ +PAM,CaCl₂+FeSO₄ +PAM, we also carry out detailed experiment in order to simulate localconditions and get the adaptation, optimum operation parameter and condition.Research shows that adsorption of hydroxyapatite defluorination performance issuperior to the activity of alumina and pH value has no effect on it, can quickly andeffectively remove the water fluoride, meet the demand for drinking water standardand can effectively improve water quality,and it has favorable applicationprospect.This study provided test data and design reference for engineering practice totreat the low fluoride-containing. Dynamic adsorption and mechanism of synthesizedhydroxyapatite should be further study.