JPS59127691A - Higher level treatment method for secondary treated human waste water - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-level treatment method for secondary treated human waste water that reduces COD (chemical oxygen demand) to a target water quality level using a complex system of bipolar activated carbon-filled electrolysis.

Emission standards for effluent from human waste treatment facilities are set by BOD according to Japan's Waste Disposal and Cleaning Law Enforcement Regulations.
-88 and the number of E. coli bacteria are specified. On the other hand, the Water Pollution Control Act designates human waste treatment facilities as specified facilities, and higher standards may be applied depending on the water usage situation at the destination.
According to environmental standards related to the living environment, if the discharge destination is a lake or sea area, COD regulations will be applied instead of BOD, and the total amount in water bodies will be regulated by the COD value.

In principle, the above extraction standard can be secured with standard dilution (20 times), but due to the difficulty of securing dilution water and the obstacles associated with extracting a large amount of effluent water, the discharge standard is set at the lowest possible dilution rate. It has become necessary to satisfy the following.

When constructing human waste treatment facilities, there are strong demands for resource conservation, downsizing of equipment, and low dilution due to location conditions.On the other hand, due to the pollution awareness of the residents involved in the discharge destination, there is an urgent need for advanced processing methods for human waste using low dilution rates. Is it the actual situation that you want to appear? There it is.

In order to cope with the above-mentioned situation, the present inventors conducted research on a method for reducing COD of secondary treated human waste water using a low dilution rate. We have completed a COD reduction method that is more economical than any other method and that cannot be achieved with other methods.

The basic structure of this invention is that after secondary treated human waste water is oxidized with ozone, water and electricity are passed through a bipolar activated carbon-filled electrolyzer filled with granular activated carbon between the positive and negative electrodes to occlude and adsorb organic matter and electrolytically oxidize it. There is a particular thing. This method brings about the effect of accurately reducing and removing substances originating from the secondary human waste treatment water (7) COI) to the target water quality level.D The reason why the method of this invention brings about the effect is as follows.
When nitrite ions (NOi) are present in the previous stage,
By injecting and contacting ozone, the COD that could not be removed in the previous stage is converted into nitric acid 7 (NOE), decolorized, and sterilized.
The remainder of
). That is, the ozonated water is led to an electrolyzer filled with activated carbon that is energized with direct current, and the scum is floated and separated through a flotation zone that floats with hydrogen and oxygen bubbles generated by water electrolysis, and the separated water is separated between the supporting electrodes. The dissolved ions are absorbed into the pores of the bipolar activated carbon, and the organic colloidal substances are adsorbed to the pore surface of the activated carbon and concentrated. It is thought that the oxygen generated by hydroelectrolysis oxidizes and decomposes the organic substances trapped in the pores, and accelerates the rate of decomposition by adsorbing and concentrating them on the surface of the activated carbon.

In order for bipolarization to occur in ACE, electron conduction occurs when activated carbon particles come into direct contact with each other, and at 7%, no electrode reaction occurs, so in order to avoid this, an adsorption capacity with pores with high contact resistance is used. It is necessary to use a certain activated carbon, and in order for this activated carbon to become bipolar, a sufficient potential gradient must occur in the treated water compared to packed granular activated carbon, and the applied voltage must be sufficiently large. It is. That is, the electrical resistance on the activated carbon side (in other words, the electrical resistance on the treated water side) is as follows: Apparent conductivity on the activated carbon side l<1>The electrical conductivity on the treated water side must be 2.

Based on this viewpoint, the present inventors have diligently studied the properties and performance of bipolar activated carbon-filled electrolyzer carbon, and have determined that the above f(1/J(
As a result of conducting tests on the consumption of activated carbon with respect to the electric power consumption rate and the current application time, etc., it was found that (
1) It is porous granular activated carbon with a particle size of 5 to 7 mm, and has an electrical conductivity of (+1
) The apparent conductivity of granular activated carbon is 1 = 1.5 to 35 m.
Kokichi found that it is effective to use porous granular activated carbon with fi/(I).The porous granular activated carbon may have a cylindrical shape as well as a spherical shape. In addition, adsorbed activated carbon can also be used. Adsorbed granular activated carbon becomes bipolar in the electrolytic zone and surface electrolysis occurs, promoting the oxidative decomposition of organic matter in the secondary human waste treatment water, so it is easy to see from the activated carbon side. t is self-regenerating, and therefore, the filled granular activated carbon has the remarkable feature that it is not necessary to replace or replace it for regeneration in the activated carbon adsorption method, and only replenishment is sufficient.

Regarding ACE, - JP-A-52-9/1651, JP-A-49-38138 and JP-A-55-1
16488, etc., and in order to make it economical and practical for high-level treatment of secondary treated human waste water, activated carbon that satisfies the conditions I'L stated in (11) and (n1) above must be used. is indispensable, and the effectiveness can be increased by effectively bipolarity.

FIG. 1 is a schematic diagram of an apparatus for carrying out the method of the present invention, and will be specifically explained with reference to the same figure. Reference numeral 1 indicates a stock solution tank, and human waste treated water is supplied to this tank through a water supply pipe 2.

3 is an onion contact tank, and 1 is installed in the stock solution tank 1.
No. 1 Human waste treated water flows in from the outlet pipe 1a. Ozone generated in Ononai→No-4 passes through conduit 4a and passes through tank 3.
Inject it into the human waste treated water in the tank and bring it into gas-liquid contact with Jl. The ozonized human waste water flows into the receiving storage tank 5 from the overflow pipe 3a. 6 is a bipolar activated carbon-filled electrolyzer (A, CE) consisting of an electrolytic zone 6a and a scum floating zone 61);
In between, granular activated carbon 9 is filled to a predetermined packing density and filling height of V%, and a DC current line 10 is connected to both poles of 2%. Pump P across the top and treated water receiving reservoir 5
A lift pipe 11 is provided, and the tops of A and CE are provided. This is connected to a liquid supply pipe 12a provided in a chemical liquid tank 12 for regenerating the granular activated carbon 9. A drain pipe 13 with a 2-t bent part in the middle is connected to the lower part of the ACE. The top of the bent portion of this pipe is positioned at the mounting position line ``2'' of the overflow pipe 14 of the scum floating zone 6b of A and CB. A to this drain pipe 13 when the ACE is out of operation.
A pipe 13a is provided to drain the water stored in the CE.

As shown in the figure, if the ozone oxidation method is used in the first step or the ACE is used in the second step, and NO ball ions are present in the secondary treated human waste water, the COD P
By injecting 0.3 minute amount of CO2 to complete the oxidation to NOi ions and decolorization of the colored components, at the same time, it promotes the reduction of the organic matter to low molecular weight and oxidizes some organic acids, so that the organic matter becomes hydrophilic, and some of the organic matter becomes hydrophilic. Ion is dissociated to this extent and I feel lucky 2
'Lru. In addition, the bipolar activated carbon filling electrolysis method is the activated carbon adsorption method.
It has a higher efficiency than the ionized carbon, and the hydrophilic organic matter that is ionized is oxidized and decomposed, but is instead occluded in the pores of the activated carbon. The occluded and concentrated organic matter on the surface of the granular activated carbon undergoes an electrolytic oxidation reaction (this is effective and cannot be expected with ozone oxidation.The oxidation reaction due to oxygen generated by water electrolysis, and the presence of ζ in the treated water) The oxidation reaction and transfer of electrons due to the effective chlorine ζ produced in the electrolytic process 71 occur during the electrolytic reaction, and the oxidizing power of the bipolar activated carbon filling electrolysis method is due to the oxidation due to ozone. It is thought that it is more powerful than physical force and can oxidize and decompose organic matter that could not be removed by the ozone oxidation method.

The scum is adsorbed by the bubbles of 2 and 02 generated during electrolysis of the treated water and floats to the surface, and is extracted from the overflow pipe 14.

The granular activated carbon filled in the electrolytic zone 6a absorbs and absorbs dissolved ions and organic substances in a double-layered manner.
It is necessary to remove this to regenerate the activity. For this purpose, sodium chloride, calcium chloride,
A supply i<=pipe 1 provided with an electrolyte solution of an alkali metal or alkaline earth metal such as sulfuric acid in a chemical tank 12
By supplying through 2a, the regenerating chemical solution can flow into the pores of the granular activated carbon, diffuse and elute the occluded/adsorbed substances, and regenerate the granular activated carbon. The concentration of the regenerating chemical solution, the liquid dispersion density (l/m2), the droplet flow rate, etc. are determined experimentally by i%.

The purpose and benefits of this invention will be made clear by the following test examples.

Test example (1) Test conditions Filling amount of granular activated carbon 350g, cathode (15 x 18 cm made of stainless steel material), anode (15 x 18 cm made of ferrite material)
33cm) -ii Flow density 0.2 A/d m2
, voltage 7.5V, sample treated water 31/I-I (CC
)I) IV+,,,22 InL? /l)(2)
Test Method As shown in FIG. 2, a comparative test was conducted between the method of the present invention and the conventional method.

The blowing Ai of 03 was 7Qnip○3 for 11 treated water.

COD is based on the potassium permanganate method at 100C.

(3) Test results It is shown in FIGS. 2 and 3.

(4) Consideration Regarding the adsorption capacity of granular activated carbon for secondary treated human urine water, the vertical axis shows the COD treatment level, and the horizontal axis shows the removed C0I) Energy consumption per weight (energy consumption + activated carbon consumption cost and regeneration) As shown in Figure 2 (3), the method using A and CE (symbol ■) is superior to the method of simply adsorbing it on granular activated carbon (symbol ■).
In terms of the reduction of C0J), there is an excellent reduction in l'V.

For comparison with the ozone method, the ozone method alone (symbol n)
In this case, we were able to reduce COJ to 22 m9/l. The method in which the ozone method was used in combination after treatment with ACE (symbol IV) yielded results that were not significantly different from those obtained using the ozone method alone (n).

After the treatment with the ozone method, the COD was significantly reduced by the method of the present invention (symbol I) in which the treatment was combined with the 'A-CE treatment. Furthermore, in the case of a method in which a granular activated carbon adsorption method is used in combination after treatment with an ozone method (mark-arrow ■), there is no significant difference from treatment using the ozone method alone (n). As shown in the results of this first test, it was confirmed that the method of the present invention resulted in a significant reduction in C0I) of 31°.

Next, C0I) for conductive dust of some granular activated carbon
A test was conducted on the achieved level, and the results are shown in Figure 3.

The stock solution used was treated water after Oson treatment (CODMn =
22ff19/l).

The particle size of the granular activated carbon (AC) used was 1.5 mm (
Comparative Example) and those with a particle size of 5 to 7 mm.

As shown in the figure, the apparent conductivity of the activated carbon layer, [m? f/
[σ] or in the range of 15 to 35, particle size 5 to 7 mm0)
JC exhibited good COD attainment levels.

According to the method of this invention, COD of 30 to 20 m9/l can be obtained with low dilution rate treated water using the known ozone oxidation method, activated carbon adsorption method, or a combination of these methods. It is desired in the field to reduce COI which cannot be achieved by the known methods21. C
OD 1.0~L5m! It is possible to achieve 7/l.

The method of this invention includes separation of components contained in secondary treated human waste water,
The removal and oxidative decomposition process, a unique single technology combination procedure that performs it, can be easily carried out even on standard dilution urine secondary treated water.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus for carrying out the method of the present invention, FIG. 2 is a chart showing test results, and FIG. 3 is a chart showing test results showing the COD attainment level with respect to changes in conductive dust of granular activated carbon. . Explanation of symbols 3 Ozone contact tank, 6/Bipolar activated carbon filled electrolyzer, 12
- Regeneration chemical tank.

Claims (1)

[Claims] 1. After the secondary treated human waste water is oxidized with ozone, the water is passed through a bipolar activated carbon-filled electrolyzer filled with granular activated carbon between the positive and negative electrodes,
High level treatment method 2 for secondary treated human waste water characterized by reducing COD in secondary treated human waste water by applying electricity to occlude and adsorb organic matter on activated carbon and electrolytically oxidizing it. The method for higher-level treatment of secondary treated human waste water according to claim 1, which is porous granular activated carbon with a diameter of 5 to 7 mm and an apparent electrical conductivity of 15 to 35171σ/a. 3. The method for higher-level treatment of secondary treated human waste water according to claim 1, wherein the granular activated carbon is regenerated by passing an electrolyte solution through the granular activated carbon packed bed.