Fluorine-containing wastewater treatment method

Abstract

The invention provides a fluorine-containing wastewater treatment method, which comprises the following steps of: detecting pH value of the fluorine-containing wastewater; adjusting the adding amount of alkali or acid solution according to the pH value detection result to control the pH value of the fluorine-containing wastewater; detecting fluorine ion concentration of the fluorine-containing wastewater, and determining the adding amount of a calcium salt according to the result; delivering the fluorine-containing wastewater to a first reaction tank and a second reaction tank in turn, stirring the wastewater and performing full mixing reaction; delivering the treated wastewater to a third reaction tank, stirring the wastewater, adding coagulant into the wastewater to generate flocculation reaction to realize solid-liquid separation, and separating calcium fluoride from the wastewater; delivering the treated wastewater to a fourth reaction tank, stirring the wastewater, and adding coagulant aid to improve the settling effect; and finally, delivering the treated wastewater into a settling tank, discharging clear solution, and filter-pressing silt into mud cakes. The fluorine-containing wastewater treatment method provided by the invention has ideal treatment effect, meanwhile saves the consumption of chemicals, and reduces the treatment cost.

Description

technical field [0001] The invention relates to a wastewater treatment method, and in particular to a fluorine-containing wastewater treatment method. Background technique [0002] Fluorine salts and fluorides are widely used in the industry. Taking semiconductor factories as an example, a large amount of Fluorides such as hydrofluoric acid (HF) or ammonium fluoride (NH4F) will naturally produce a large amount of fluorine-containing wastewater. In order to recover the fluoride content in the waste water and reduce the fluorine concentration in the waste water discharge. [0003] Among the various treatment methods of fluorine-containing wastewater, the calcium salt precipitation method is widely used due to its advantages of low cost, easy operation, and short reaction time. Fluoride ions in wastewater react to form calcium fluoride precipitates, and the reaction formula is as follows: [0004] Ca 2+ +2F - →CaF 2 [0005] Then some solid-liquid separation processes ca...

AI Technical Summary

Problems solved by technology

[0011] However, in the prior art, the pH meter is used to measure the pH value of the wastewater multiple times, and acid or alkali is added to adjust the wastewater to a neutral state. However, the surface of the pH meter is very easy to scale, resulting in inaccurate pH monitoring and waste of acid. Alkali, which increases the consumption of chemicals, while the increased acidity and alkalinity also increases the consumption of calcium chloride

The fluoride ion concentration detection in the prior art uses a simple fluorine electrode, which has low measurement accuracy and high consumption, and is prone to fouling, resulting in inaccurate measurement, which easily leads to inaccurate calcium chloride addition.

At the same time, in the prior art, the fluoride ion concentration is detected multiple times, and calcium chloride is added multiple times, which is extremely inconvenient and increases the processing procedures and corresponding costs.

In the prior art, the treatment time of each treatment step is too short, resulting in insufficient reaction between fluorine-containing wastewater and calcium chloride in the reaction step, thereby wasting the consumption of calcium chloride, and short growth time of calcium fluoride crystallization in the precipitation step , can not be completely precipitated resulting in unsatisfactory treatment effect

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