Experimental Study on Treatment of Fluorine-containing Industrial Wastewater by Precipitation Coagulation
The traditional calcium salt precipitation method can not meet the enterprise emission standards,and the interaction of fluoride removal conditions when calcium salt precipitation method is combined with other processes has a decisive influence on the fluoride removal results.In order to solve the problem of fluoride removal in secondary cooling water of continuous casting in a steel plant,the simulated raw water was used for experiments,and the process route of adding efficient fluoride removal agent after calcium salt precipitation treatment was adopted,and the single factor experimental analysis was carried out.Taking the dosage of calcium salt,precipitation reaction time,dosage of composite fluoride removal agent and coagulation pH of composite agent as influencing factors,the optimal experimental conditions were determined with the mass concentration of residual fluoride ions in the effluent as the index.The results showed that when calcium hydroxide and calcium chloride were used as precipitant,the molar ratio of calcium hydroxide to calcium chloride was 1∶1,the molar ratio of calcium to fluorine was 1.21∶1,the precipitation reaction time was 28 min,the coagulation reaction pH was 6.2,and the dosage of composite agent was 46 mg·L-1,the fluoride ion mass concentration in the effluent was stabilized below 2 mg·L-1.
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