KR101205065B1 - Process for removing phosphate from wastes water - Google Patents

Abstract

The present invention relates to a method for treating phosphate in wastewater, by using blast furnace slag quenched slag generated during pig iron production in a blast furnace to remove phosphate in wastewater.
The present invention is to significantly reduce the cost of phosphate removal.
In addition, the present invention can recycle the slag used to remove the phosphate as a cement aggregate or fertilizer to improve the economics, as well as to have a useful effect of reducing the discharge of sludge during wastewater treatment.

Description

Phosphate treatment of wastewater {PROCESS FOR REMOVING PHOSPHATE FROM WASTES WATER}

The present invention relates to a method for treating phosphate in wastewater, and more particularly, to a method for treating phosphate in wastewater, which enables the treatment of phosphate contained in wastewater using slag generated in a steelmaking process.

In general, industrial wastewater contains a variety of pollutants, and wastewater containing phosphorus (P) contains nitrates or organic matter.

Heavy metals, fluorine, and phosphorus in the industrial wastewater are removed using aluminum sulfate as a chemical flocculant.

However, when nitrates or organic substances are contained in the wastewater, water treatment is carried out using a biological treatment system. In general, phosphorus (P) is first removed before biological treatment systems and then nitrates or organic substances are removed.

In addition, since industrial wastewater, such as semiconductors and LCDs, contains a large amount of phosphate along with nitrate, slaked lime or alumina sulfate is added to remove phosphate before a biological treatment system for treating nitrate.

It is an object of the present invention to provide a method for treating phosphate in wastewater, which enables economic removal of phosphate contained in wastewater by using slag generated in steelmaking and steelmaking processes.

This object of the present invention is solved by providing a phosphate treatment method of wastewater to remove the phosphate contained in the wastewater by passing the wastewater through the packed column filled with the slag particles having a diameter of more than 0 and less than 1mm.

A first step of collecting the wastewater containing phosphorus (P) into the sump,

The phosphate contained in the wastewater was supplied to the inside of the packed column filled with the water slag particles having a diameter of 1 mm or less exceeding the collected wastewater and retained in the packed column as the calcium (Ca) component of the water slag. Including the second step of removal to remove the phosphate contained in the waste water.

The resin slag particles are formed by crushing the resin slag quenched from the blast furnace slag produced in the furnace to have a diameter of more than 0 and less than 1mm.

The present invention has the effect of drastically reducing the cost of phosphate removal by removing the phosphate contained in the waste water by using the slag generated in the steelmaking process or steelmaking process.

In addition, the present invention can recycle the slag used to remove the phosphate as a cement aggregate or fertilizer to improve the economics, as well as to have a useful effect of reducing the discharge of sludge during wastewater treatment.

1 is a block diagram schematically showing a process for treating phosphate in wastewater according to the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is to remove the phosphate salt in the waste water by crushing the water slag into the wood slag particles having a diameter of more than 0 and 1mm or less and then filling the wood slag particles in the packed tower and then passing the waste water through the packed tower.

The present invention is to remove the phosphate of the wastewater by the manual slag particles, the first step of collecting the wastewater containing phosphorus (P) in the sump tank,

The phosphate contained in the wastewater was supplied to the inside of the packed column filled with the water slag particles having a diameter of 1 mm or less exceeding the collected wastewater and retained in the packed column as the calcium (Ca) component of the water slag. It includes a second step of elimination.

When iron is made from iron ore in a blast furnace, silicon, aluminum, calcium, and the like in the iron ore remain as oxides and are melted without being reduced.

In addition, molten iron remains in the lower part of the furnace, and molten oxide remains in the upper part, and the molten oxide is blast furnace slag, and the slag is generated when the blast furnace slag is rapidly cooled with a high pressure cooling water.

The slag slag has a needle-like structure and when crushed, it is easily powdered into a slag particle having a diameter of more than 0 and 1mm or less.

Examples of the component ratio of such a resin slag are shown in Table 1 below.

ingredient CaO SiO ₂ Al ₂ O ₅ MgO MnO Total
Fe TiO ₂ P ₂ O ₅ content
(wt%) 35-45 30-45 10 to 15 5 ~ 8 0.3 ~ 0.7 0.4-1.5 0.5 to 0.7 N.D.

As shown in Table 1, it can be seen that the CaO content is 35 ~ 45wt%, which can remove phosphate through Scheme 1.

[Reaction Scheme 1]

5Ca ²⁺ + 3PO ₄ ^3- + OH ^- ↔ Ca ₅ (PO ₄ ) ₃ OH (s)

As in Scheme 1 above, the phosphate is reacted with a calcium compound to solidify, and this solid is treated with solids like sludge.

Through the preferred embodiment of the present invention will be described in more detail. Based on Scheme 1, an experiment was performed to remove phosphate using the handmade slag particles.

Example 1

Phosphate concentration 1ppm, 1.5ppm, 2ppm test solution of 5g each of the slag was added to each reaction for 10 minutes while stirring to see the change in the concentration of phosphorus, phosphorus was not detected anywhere in each test solution.

[Example 2]

When the concentration of initial phosphoric acid is adjusted to 10 P mg / L aqueous solution, 5 g of handmade slag particles having a diameter of 1 mm, 5 g of handmade slag particles having a diameter of 2 mm, and 5 g of handmade slag particles having a diameter of 4.5 mm are added to the aqueous solution. Residual phosphate concentration over time is shown in Table 2 below.

Reaction time
(min)
Residual Phosphate Concentration (mg / L) 1mm handmade slag particles
(5 g) 2mm handmade slag particles
(5 g) 4.5mm handmade slag particles
(5 g) 0 10 10 10 5 1.5 2.7 5.1 10 N.D. 1.2 3.8 20 N.D. N.D. 1.6 30 N.D. N.D. N.D.

That is, it can be confirmed that the removal time of the phosphate is the shortest when using the handmade slag particles having a diameter of 1mm as confirmed in Table 2.

The slag particles having a diameter of more than 0 and 1 mm or less have a high adsorption surface area and are excellent in phosphate removal efficiency.

Therefore, it is preferable to remove the phosphate in the waste water by using the slag particles having a diameter of more than 0 and 1 mm or less and having a large adsorption surface area.

Industrial Applicability The present invention can be utilized for a pretreatment system for wastewater containing a large amount of nitrates and organic matters, such as wastewater in the electronics industry. More preferably, it is applicable to systems for the pretreatment of biological treatment systems for treating nitrates and organics.

First, in the wastewater treatment system used in the present invention, as shown in FIG. 1, a water collecting tank 10 for collecting industrial wastewater containing phosphorus and the above-mentioned slag particles S having a diameter of more than 0 and 1 mm or less are filled. It consists of a packed tower 20, a storage tank 30 for input into a reactor, such as a biological treatment system, and a settling tank 50 for the final discharge of the waste water divided into sludge and waste water.

 The filling tower 20 is filled with the wood slag particles (S) in the same manner as the general sand filtration and activated carbon filtration, the supply pipe 12 to which the wastewater of the sump (10) is supplied is connected to the top, backwashing The back washing pipe 14 is connected to the lower part, and the return pipe 25 is connected to the upper part so that the waste water in the filling tower 20 is returned back to the water collecting tank 10 side.

In the backwash pipe, an on-off valve 15 is arranged to cut off the supply of waste water.

The method for removing phosphate in waste water is as follows.

After the industrial wastewater is collected in the water collecting tank 10, and the collected wastewater is supplied into the filling tower 20 through the supply pipe 12, the filling tower until draining to the storage tank 30 in the filling tower 20. (20) During staying inside, the calcium component of the handmade slag particles (S) is chemically reacted with the phosphate component contained in the wastewater on the basis of the above reaction formula 1 and solidified with calcium compound to remain inside the packed tower 20. The wastewater from which the phosphate is removed is drained to the storage tank 30 which is a biological treatment system which is a later process.

In addition, the backwashing process of backwashing the wastewater of the sump tank 10 from the lower part of the filling tower 20 to the upper side is periodically performed.

At this time, during the backwashing process, the solidified calcium compound and wastewater are sent to the collection tank 10 for reprocessing.

The residence time of the wastewater filling tower 20 is preferably maintained for about 10 minutes to 30 minutes.

It is preferable to maintain the above range because the removal efficiency of phosphate is lowered when it is less than 10 minutes, and when the efficiency is lowered when it exceeds 30 minutes.

In addition, when the phosphate removal efficiency of the filling tower 20 is lowered, the water-containing slag particles (S) of the filling tower 20 can be utilized for aggregates, fertilizer raw materials, and the like.

The wastewater drained to the storage tank 30 has a process of being separated into sludge and wastewater in the settling tank 50 after the reaction treatment through the reaction tank 40 in the same manner as the conventional biological treatment system.

Therefore, the present invention has the advantage of minimizing the running cost and sludge generation when treating the phosphate in the wastewater using the wood slag.

10: sump tank 12: supply piping
14: backwash piping 15: on-off valve
20: filling tower 25: return piping
30: storage tank 40: reaction tank
50: sedimentation tank S: wood slag particles

Claims (3)

delete The wastewater is passed through a packed column filled with water slag particles having a diameter greater than 0 and less than 1 mm to remove phosphate contained in the wastewater.
A first step of collecting the wastewater containing phosphorus (P) into the sump,
The phosphate contained in the wastewater was supplied to the inside of the packed column filled with the water slag particles having a diameter of 1 mm or less exceeding the collected wastewater and retained in the packed column as the calcium (Ca) component of the water slag. A phosphate treatment method for wastewater, characterized in that to remove the phosphate contained in the wastewater, including the second step of removing. The wastewater is passed through a packed column filled with water slag particles having a diameter greater than 0 and less than 1 mm to remove phosphate contained in the wastewater.
The said slag particle is phosphate treatment method for wastewater, characterized in that the blast furnace slag generated in the blast furnace was formed by crushing the resin slag quenched to have a diameter of more than 0 to 1mm or less.

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