Precipitation Methods Using Calcium-Containing Ores for Fluoride Removal in Wastewater

Abstract

F-containing wastewater does great harm to human health and the ecological environment and thus needs to be treated efficiently. In this paper, the new calcium-containing precipitant calcite and aided precipitant fluorite were adopted to purify F-containing wastewater. Relevant reaction conditions, such as reaction time, oscillation rate, dosage of hydrochloric acid, calcite dosage and the assisting sedimentation performance of fluorite, and action mechanism are analyzed. The experiment showed that the removal rate of fluoride in simulated wastewater reached 96.20%, when the reaction time, the dosage of calcite, the dosage of 5% dilute hydrochloric acid, and the oscillation rate was 30 min, 2 g/L, 21.76 g/L, and 160 r/min, respectively. Moreover, the removal rate of fluoride in the actual F-containing smelting wastewater reaches approximately 95% under the optimum condition of calcite dosage of 12 g/L, reaction time of 30 min, and oscillation rate of 160 r/min. The addition of fluorite significantly improves the sedimentation performance of the reactive precipitates. The experimental results showed that calcite and fluorite can effectively reduce the concentration of fluoride ions in F-containing wastewater and solve the problem of slow sedimentation of reactive precipitates.

Management of Solid Waste Containing Fluoride—A Review

“…As the aforementioned fluoride-originated pollutants raise several health problems, the World Health Organization (WHO) determined the acceptable level of fluoride content in drinking water at the level of 1.5 mg/L [ 45 ]. However, the concentration of fluorides in industrial wastewater mostly exceeds these WHO guidelines, reaching even thousands of milligrams per litre [ 40 , 84 , 85 ]. Thus, fluoride pollution in the aquatic environment, caused by natural and artificial activities, has been a significant problem worldwide.…”

Electrocoagulation as a Promising Defluoridation Technology from Water: A Review of State of the Art of Removal Mechanisms and Performance Trends

“…Incident of crippling fluorosis, thyroid disorder, infertility in women, cancer, and Alzheimer's syndrome Different processes have been evaluated to reduce high fluoride concentrations in water and, consequently, to prevent hazardous health effects. Some examples of examined technologies include adsorption [11][12][13], chemical precipitation using lime or magnesium salts [14,15], co-precipitation and adsorption through coagulation-flocculation with alum [16,17], ion exchange [18,19], electrodialysis [20][21][22], and electrocoagulation [23,24]. Amongst these technologies, electrocoagulation (EC) has emerged in recent decades as a suitable alternative compared to the conventional coagulation process.…”

“…For a continuous reactor, Rosales et al [87] indicated that residual fluoride concentration had a linear trend with flow rate at 6 A cm −2 ; in contrast, such trend was not observed for 4 A cm −2 and 8 A cm −2 due to the interferences with co-existing ions. Considering Equation (15), current density also affects energy consumption leading to an increase in operating costs. Rosales et al [87] reported that the energy consumption increased (36.78, 93.87, 160.83 kWh m −3 ) by an increase in current density (4, 6, 8 mA cm −2 ); it was confirmed that for each current density increasing in flow rate (decrease in retention time) caused the reduction of energy consumption.…”

An Effective New Treatment of Fluoride-Containing Sludge Resulting from the Manufacture of Photovoltaic Cells

“…Jiang and Zhou studied the effect of aluminum on the treatment of fluorinecontaining synthetic wastewater by crystallization [8]. Wang et al [9] demonstrated the effectiveness of calcium-containing precipitant calcite together with added precipitant fluorite to purify F-containing wastewater.…”