JPH06480A - Treatment of waste water - Google Patents

Abstract

PURPOSE:To inexpensively and efficiently reduce COD and chromaticity by adding an appropriate substance to waste water so as to form at least one of sodium hypochlorite or caustic soda to form an electrolytic solution and apply DC voltage to the solution. CONSTITUTION:A passage 2 of waste water X is formed between positive and negative electrode plates 1 for electrolytically treating waste water X in a waste water treatment apparatus. An appropriate solution Y is added to waste water X so as to form at least one of sodium hypochlorite and caustic soda to form an electrolytic solution which is, in turn, supplied to the passage in a definite ratio by a pump P in such a state that DC voltage is applied to the positive and negative electrode plates 1. By this constitution, formed sodium hypochlorite or caustic soda is reacted with org. matter to promote the reduction of COD and chromaticity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method.

[0002]

2. Description of the Related Art Conventionally, various methods have been adopted for treating domestic and industrial wastewater. In other words, laws and regulations establish wastewater standards to prevent water pollution, and in order to reduce the pollution load of water quality indicators that are regulated by this wastewater standard, coagulation sedimentation methods, biological treatment methods, and other wastewater to be treated A wide variety of wastewater treatment methods have been put into practical use according to their characteristics. As the water quality index, there are COD (chemical oxygen demand), chromaticity, etc. as an index of water quality pollution by organic substances.

By the way, with increasing international awareness of environmental protection, wastewater standards, especially those concerning COD and chromaticity tend to be strengthened, and there is a demand for a wastewater treatment method that can be efficiently processed at low cost.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to propose a wastewater treatment method capable of efficiently reducing COD and chromaticity at low cost.

[0005]

In order to solve the above problems, the present invention takes the following technical means.
That is, in the wastewater treatment method of the present invention, an appropriate substance is added to the wastewater X so that at least one of sodium hypochlorite and caustic soda is produced to form an electrolyte solution, and a DC voltage is applied to the electrolyte solution. did. Further, salt may be added to the drainage X, or seawater may be added to the drainage X.

[0006]

As a result of adopting the above means, the present invention has the following effects. (Operation of the Invention According to Claim 1) An appropriate substance is added to the waste water X so that at least one of sodium hypochlorite and caustic soda is produced to form an electrolyte solution, and a DC voltage is applied to this electrolyte solution. By the way, although the detailed reaction mechanism is unclear, it is possible that the generated sodium hypochlorite and caustic soda react with organic matter, resulting in COD.
And, it is possible to actually promote the reduction of chromaticity. (Operation of the invention according to claim 2) In addition to the above-mentioned operation, the following operation is provided.

When salt is added to the wastewater X, sodium hypochlorite and caustic soda are produced in the wastewater X. (Operation of the Invention of Claim 3) In addition to the above-mentioned operation, the following operation is provided. By adding seawater to the drainage X, the drainage X can be inexpensively used as the electrolyte solution of the above-described embodiment.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below with reference to the drawings showing preferred embodiments. FIG. 1 is a wastewater treatment apparatus for explaining a first embodiment of the present invention, in which a drainage passage 2 is formed between positive and negative electrode plates 1 for electrolytically treating the wastewater X. Then, with a DC voltage being applied to the positive and negative electrode plates 1, the drainage used as the electrolyte solution is fed into the passage 2 using the pump P.

To this wastewater treatment device, a wastewater to be treated (hereinafter referred to as raw water X) and a solution Y added to make the raw water X into an electrolyte solution are supplied by a pump P at a constant ratio. Using this wastewater treatment equipment, treatment was performed in each of the following cases. (1) When sodium hypochlorite or caustic soda was added to raw water to form an electrolyte solution Raw water having a COD value of 160 ppm was treated as follows. 50 cc of NaOCl was added to 1000 cc of raw water to make an electrolyte solution, and electrolysis was performed at a flow rate of about 160 cc / min. As a result, a current of 24 A flows and the CO
The D value was 32 ppm. 5cc of NaOH and Na for 1000cc of raw water
Add 10 cc of OCl to make electrolyte solution, about 160 cc
Electrolysis was performed at a flow rate of / min. As a result, 32A
The current flowed and the COD value after the treatment was 24 ppm.

That is, when sodium hypochlorite or caustic soda is directly added to the waste water to be treated to form an electrolyte solution, the COD value reduction effect is actually large as shown in the measurement results. (2) When 30% saline was added to raw water to form an electrolyte solution 30% saline was added to the raw water at a ratio of 4: 1 to form an electrolyte solution, and electrolysis was performed at a flow rate of about 160 cc / min. The following table shows the measurement results of the COD value (ppm), the amount of suspended solids SS (ppm), etc.

COD SS Duck chromaticity pH Free residual chlorine (ppm) (ppm) (ppm) (ppm) Raw water 176 23 159 810 7.9 63 63 33 58 271 6.3 2.19 46 7 26 26 120 7.3 1 .31 5 13 27 122 122 7.5 0.51 3 17 31 169 7.3 0.50 In the above table, a DC voltage of 2.8 V was applied and a current of 10 A was applied.

A DC voltage of 4.1 V is applied to apply a current of 20
Flowed A. A direct current voltage of 5.0 V was applied and a current of 30 A was passed. A DC voltage of 7.0 V was applied and a current of 40 A was passed. From the above measurement results, in each example from COD
The value and the chromaticity are extremely reduced, and the effect of reducing the COD value and the chromaticity is greater when a large current is applied. (3) When 7% saline solution was added to raw water to prepare an electrolyte solution 7% saline solution was added to the raw water at a rate shown in the following table to prepare an electrolyte solution, and electrolysis was performed at a flow rate of about 160 cc / min.
The COD value of raw water is 123.6 ppm, and C
The measurement results of the OD value (ppm) are shown in the following table.

Raw water (cc) Sea water (cc) Current value (A) COD (ppm) 900 100 100 20 46.6 800 200 30 30 38.5 700 300 38 38 24.7 600 400 44 44 30.9 500 500 50 50 29.0 As is clear from this measurement result, 123.
The COD value, which was as high as 6 ppm, is significantly reduced in each of the cases. (4) When Sea Water is Added to Raw Water to Form an Electrolyte Solution Sea water (salt content of about 7%) was added to the raw water to form an electrolyte solution, and electrolysis was performed at a flow rate of about 160 cc / min. The COD value of raw water is 123.6 ppm, and the measurement result of the COD value (ppm) after the treatment is shown in the following table.

Raw water (cc) Seawater (cc) Current value (A) COD (ppm) 900 100 100 14 76.0 800 200 200 16 40.9 700 300 300 19 38.5 600 400 21 21 32.3 500 500 26 26 24.2 Oxygen, chlorine and hydrogen were generated by electrolysis.

As is clear from the measurement results, the COD value of 123.6 ppm in raw water was significantly reduced in each of the following cases. Further, as the salt content increases, the current flowing through the electrolyte solution increases, and a better COD value after treatment tends to be obtained. Seawater has a maximum salinity of about 30%, usually about 10%, and is advantageous in that it is easily supplied, especially at coastal areas, and can be obtained at a low cost.

FIG. 2 shows a wastewater treatment equipment for explaining the second embodiment of the present invention, and the difference from the first embodiment will be mainly described. This wastewater treatment device comprises an outer cylinder 3 made of a conductive material and an inner cylinder 4 arranged in the outer cylinder 3 and made of a conductive material. An untreated tank 30 and a treated tank 31 are formed in the outer cylinder 3, and the inner cylinder 4 is arranged in the untreated tank 30 and has a plurality of holes 40. The circumference of the inner cylinder 4 is covered with a filter material 41 for performing filtration separation, and the wastewater to be treated is bored in the untreated tank 30 → pores for filtration separation formed in the filter material 41 → inner cylinder 4. It is guided to the outside through a path of the plurality of holes 40 → inside the inner cylinder 4 → the processed tank 31. Reference numeral 5 is an insulating member for electrically insulating the outer cylinder 3 and the inner cylinder 4.

Raw water, a solution Y added to make the raw water into an electrolyte solution, and activated carbon AC as a filter aid are supplied to the waste water treatment device by a pump P at a constant ratio. Furthermore, a cathode is connected to the outer cylinder 3 and an anode is connected to the inner cylinder 4, and electrolysis is performed by applying a DC voltage between the outer cylinder 3 and the inner cylinder 4. According to the wastewater treatment method of this embodiment, as in the first embodiment, there is an advantage that the COD of the wastewater can be significantly reduced and at the same time, the suspended matter contained in the wastewater can be removed by filtration separation.

[0018]

The present invention having the above-mentioned structure has the following effects. (Effect of the Invention of Claim 1) Since COD and chromaticity can be promoted to be reduced by the action of the generated sodium hypochlorite and caustic soda, COD and chromaticity can be efficiently reduced at low cost. We can provide wastewater treatment methods. (Effect of invention of Claim 3) In addition to the above effect, it has the following effect.

Since the waste water X can be inexpensively used as the electrolyte solution of the above-mentioned embodiment, an inexpensive waste water treatment method can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory view of a wastewater treatment equipment for explaining a first embodiment of a wastewater treatment method of the present invention.

FIG. 2 is an explanatory view of a wastewater treatment equipment for explaining a second embodiment of the wastewater treatment method of the present invention.

[Explanation of symbols]

 X drainage

Claims (3)

[Claims] 1. A wastewater treatment method comprising adding an appropriate substance to wastewater X so that at least one of sodium hypochlorite and caustic soda is formed into an electrolyte solution, and applying a DC voltage to the electrolyte solution. . 2. The wastewater treatment method according to claim 1, wherein salt is added to the wastewater X. 3. The wastewater treatment method according to claim 1, wherein seawater is added to the wastewater X.