JPS58199089A - Treatment of waste water containing fluorine together with surfactant - Google Patents

Abstract

PURPOSE:To improve removing efficiency while saving the amt. of the chemical to be added, by subjecting waste water to an adsorptive treatment of surfactant with activated carbon at specific pH then adding the chemical thereto and separating and removing fluorine as hardly soluble salt. CONSTITUTION:Raw water is introduced through a raw water introducing pipe 1 into a pH control tank 2, where the water is mixed with the acid or alkali fed through a feed port 3 and is controlled to >=3pH. The raw water is then introduced into an adsorptive treatment tank 4 using activated carbon. The surfactant contained in the raw water is adsorbed by the activated carbon in said tank and removed. The raw water after the adsorptive treatment is introduced into a pH adjusting tank 5, where the pH is properly controlled in the same way and the treated water is introduced into a flocculation tank 7. The water is thoroughly mixed with a calcium compd., a calcium compd. in combination with a phosphoric acid compd. or a metallic salt fed through a feed port 8 in the tank 7, whereafter, the mixed water is transferred into a settling tank 9 and the fluorine compd. is settled and separated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating fluorine-containing wastewater in which a surfactant coexists.

In wastewater discharged from semiconductor factories, aluminum electrolytic smelting factories, phosphate fertilizer manufacturing factories, etc.

Contains fluorine ions and surfactants. Conventionally, methods for removing fluoride ions from wastewater include adding water-soluble calcium compounds to the wastewater.

For example, adding calcium hydroxide, calcium chloride, etc.
A method is known in which the poorly soluble calcium fluoride produced is separated by precipitation.

Alternatively, there is a method in which calcium ions and phosphate ions are added at a pH around neutrality to precipitate and separate as phosphate a-ξtite, or a method in which a metal salt is added to precipitate and separate as a sparingly soluble salt of metal and fluoride ions. As a countermeasure for this,
Existing excess calcium compounds, calcium phosphate, and metal salts are added, which has the disadvantage of increasing costs.

The object of the present invention is to overcome the drawbacks of the prior art.

Our objective is to provide a wastewater treatment method that can efficiently remove fluorine while reducing the amount of chemicals added.
This is achieved by pretreatment with activated carbon at 3 or more.

According to the present invention. The method for treating fluorine-containing wastewater in which a surfactant coexists is to adjust the pH of the wastewater to 3 or higher, remove the surfactant from the wastewater by adsorption treatment with activated carbon, and then adjust the pH as necessary. , is characterized in that a water-soluble calcium compound or a water-soluble calcium compound and a water-soluble phosphoric acid compound or metal salt are added, and fluorine is separated and removed as a sparingly soluble salt.

When the pH of the target wastewater is 3 or less, activated carbon adsorbs fluorine ions and adjusts the adsorption amount of surfactant to -6°10. To adjust the pH, a mineral acid such as hydrochloric acid or sulfuric acid or an alkaline agent such as sodium hydroxide or calcium hydroxide can be used.

In this way, when wastewater is adsorbed with activated carbon at a pH of 3 or higher,
Since the activated carbon selectively adsorbs the surfactant, the subsequent precipitation and removal of fluorine is preferably carried out without being inhibited.

Calcium compounds used in the present invention include:

Commonly used water-soluble calcium compounds such as calcium hydroxide and calcium chloride can be used, and as phosphoric acid compounds, phosphoric acid or its salts, eg salts, etc. can be used. . When using calcium and phosphate compounds, fluorine is precipitated and removed as fluoroapatite.

As the metal salt, a metal salt 2 that can form a poorly soluble salt with fluorine, such as an aluminum salt or a magnesium salt, can be used.

Next, the present invention will be explained in detail based on two drawings.

Raw water is introduced into the pH adjustment tank 2 through the raw water introduction pipe 1.

Mix with acid or alkali injected from injection port 3 to adjust raw water to pH 3 or higher. The raw water whose pH has been adjusted in this way is then introduced into the activated carbon adsorption treatment device 4. Here, the surfactant contained in the raw water is adsorbed and removed by activated carbon. Next, the raw water subjected to the adsorption treatment is introduced into the pH adjustment tank 5, and after adding acid or alkali through the inlet 6 to adjust the pH appropriately, the raw water is introduced into the aggregation tank 7. In the flocculation tank 7,
After thoroughly mixing with the calcium compound, calcium compound and phosphoric acid compound, or metal salt injected from the injection port 8, the mixture is fed into the precipitation tank 9 and subjected to precipitation separation.

In this manner, according to the present invention, fluorine can be efficiently removed without being interfered with by surfactants.

Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

Example: Waste water containing surfactant and fluorine (adjusted to pH 5 with 3001' soda in F, water passed through an activated carbon bed (column with inner diameter of 5.0 m and length of 100 cm) at 5 V = 2, resulting in activated carbon treatment. The F concentration of water is 280-7t.

TOC was 150 μ/l. Afterwards, coagulation-sedimentation treatment was performed using lucium chloride as a calcium compound, and the F concentration in the treated water was reduced to 15/F or less, whereas in the conventional method without activated carbon treatment, the CQ/F molar ratio was 2. However, in the method of the present invention, the molar ratio of 0,072 becomes 1, and the amount of calcium chloride added can be reduced to 215.

[Brief explanation of the drawing]

The drawing is a flow sheet showing one embodiment of the method of the present invention. Explanation of symbols 2.5...pH adjustment tank 4...Activated carbon adsorption treatment device 7...Coagulation tank 9...Settling tank.

Claims (1)

[Claims] fl) PH of fluorine-containing wastewater in which surfactants coexist.
After adjusting the pH to 3 or higher, adsorption treatment is performed with activated carbon. After adjusting the pH again as necessary, a water-soluble calcium compound, a water-soluble calcium compound, and a water-soluble phosphoric acid compound or metal salt are added. A method for treating fluorine-containing wastewater in which a surfactant coexists, characterized by separating and removing fluorine as a sparingly soluble salt.