JP3420869B2 - Advanced treatment method and treatment equipment for human wastewater - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating night soil-based wastewater such as night soil, septic tank sludge, landfill leachate wastewater, and a mixture thereof, and in particular, a light irradiation treatment for light irradiation in the presence of a photocatalyst is used in combination. The present invention also relates to a method for treating human waste sewage capable of completely removing COD and chromaticity components, and a treatment apparatus to which the method can be applied efficiently.

[0002]

2. Description of the Related Art At present, the most advanced treatment method for human sewage wastewater is biological nitriding and denitrification treatment of human waste sewage undiluted, followed by membrane separation with a UF membrane, and aluminum permeation water or chloride chloride. 2 Inorganic coagulant such as iron is added to coagulate phosphate ions and COD, and the coagulated flocs are further U
This is a treatment method in which COD remaining in the membrane-permeated water is separated by the F membrane and adsorbed and removed by the granular activated carbon in the final step to obtain highly treated water. This advanced treatment method is called the membrane separation process,
One of the features is that it has an activated carbon treatment step in the final step.

The treated water from the treatment facility for human waste water is often discharged directly to a clean small river with a small amount of flowing water, so that it is required to treat the water to a quality as good as possible. In the membrane separation process of night soil, there are organic substances that cannot be adsorbed and removed by the treatment with activated carbon.
It was not possible to completely remove the OD and chromaticity components. In addition, the final process of activated carbon treatment process treated water COD
However, if the discharged water quality standard value, which is usually 10 to 15 mg / liter, is exceeded, the activated carbon must be regenerated, so the regeneration frequency is high, maintenance is complicated, and the treatment cost is large. There were problems with the membrane separation process.

[0004]

[Problems to be Solved by the Invention] [Problems to be Solved by the Invention] The above-mentioned problems of the conventional membrane separation process of human urine are solved, a maintenance apparatus is easily provided, a treatment cost is low, and a urinary wastewater treatment method and a treatment apparatus capable of efficiently applying the method are provided. This is the subject of the present invention.

[0005]

The above-mentioned problems of the present invention are as follows.
(1) Human urine characterized by biologically nitrifying and denitrifying human waste sewage, coagulating and separating it with an inorganic coagulant, treating the separated water with activated carbon, and irradiating the activated carbon-treated water with light while contacting it with a photocatalyst. To provide an advanced treatment method for system wastewater,
And (2) at least a biological nitrification and denitrification treatment device including a denitrification tank and a nitrification tank, a coagulation separation tank and an activated carbon treatment tank is provided, and after the activated carbon treatment tank, a photocatalyst It is possible to solve the problem by providing a human waste sewage treatment apparatus, which is characterized in that a photocatalytic oxidation unit that irradiates light in the presence is provided.

The essence of the technical idea of the present invention is to irradiate the treated water treated by the conventional membrane separation process of biological nitrification and denitrification treatment, coagulation separation with an inorganic coagulant and then activated carbon treatment in the presence of a photocatalyst. To completely remove the COD and chromaticity components of the treated water by oxidizing it, and for that purpose, the activated carbon treatment tank and the tank filled with the photocatalyst dispersed in the treated water and the active tank The purpose is to provide a photocatalytic oxidation part consisting of a light source for irradiating light rays. In the treatment of night soil sewage, there has been no concept of oxidative decomposition of COD and chromaticity components of treated water by irradiation with light in the presence of a photocatalyst after treatment with activated carbon.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION One example of steps for carrying out the present invention is shown in FIG. 1, and the present invention will be described with reference to FIG. In FIG. 1, the treatment apparatus for night soil-type wastewater of the present invention comprises a biological nitrification denitrification treatment apparatus comprising a denitrification tank 1 and a nitrification tank 2, a membrane separator 3,
It consists of a photocatalytic oxidation part having a coagulation separation tank 4, a membrane separator 5, an activated carbon treatment tank 6 and a photooxidation tank 7. The human waste water 8 is denitrified in the state of being undiluted or diluted to an appropriate dilution ratio. It flows into the tank 1 and circulates between the denitrification tank 1 and the nitrification tank 2 for anaerobic nitrification and denitrification. The nitrification-denitrification treated wastewater is subjected to solid-liquid separation by the membrane separator 3, and the biological treatment separated water 9 is transferred to the coagulation separation tank 4. Coagulation separation tank 4
In the biological treatment separated water 9, an inorganic flocculant 11 such as aluminum sulfate or ferric chloride is added to flocculate SS containing phosphate ions and COD, and the flocculated flocs are subjected to solid-liquid separation by the membrane separator 5. Then, the coagulated separated water 10 is transferred to the activated carbon treatment tank 6 filled with activated carbon to adsorb and remove COD and chromaticity components. The activated carbon-treated water is then transferred to the photooxidation tank 7 where it is irradiated with light in the presence of a photocatalyst to oxidize and remove the remaining COD and chromaticity components. The treated water treated by the treatment apparatus for human waste system wastewater of the present invention is discharged outside the system as discharged water 12.

The photocatalytic oxidation section having the photooxidation tank 7 of the present invention is a method of irradiating light from the free surface of the tank in which the water to be treated in which the photocatalyst is suspended and dispersed is stored. A method of irradiating the water to be treated in which the flowing photocatalyst is suspended and dispersed with light from around the pipe, or a method of irradiating the water to be treated in a tank containing the water to be treated in which the photocatalyst is suspended and dispersed. Either method may be used.

As described above, the activated carbon-treated water of the present invention is further irradiated with light in the presence of a photocatalyst, and the remaining COD
The treatment method of oxidizing and decomposing the chromaticity component to completely remove it has the following great advantages. That is,
When the activated carbon treatment is the final treatment as in the conventional membrane separation process, the activated carbon is regenerated when the COD of the treated water exceeds the discharge water quality standard value even if the activated carbon still has the COD treatment capacity. It had to be treated, and had the disadvantage that it had to be regenerated before the adsorption capacity of the activated carbon was fully used up. However, in the present invention, when the activated carbon-treated water is irradiated with light in the presence of a photocatalyst, COD and chromaticity components remaining in the activated carbon-treated water are photooxidized, so that the activated carbon is regenerated even if the activated carbon-treated water exceeds the discharge water quality standard value. Water can be continuously passed through the activated carbon without treatment. As a result, the COD treatment capacity of activated carbon can be used up to the maximum, and the frequency of regeneration treatment of activated carbon is greatly reduced.

According to the experiments conducted by the present inventors, after removing BOD from the night soil sewage by a usual activated sludge treatment method,
When the aggregated water obtained by adding an inorganic aggregating agent and aggregating SS containing phosphate ions and COD without irradiating nitrogen components is irradiated with active light in the presence of a photocatalyst, a large amount of ammoniacal It was found that the photocatalytic oxidation reaction preferentially causes the nitrification reaction of ammoniacal nitrogen due to the residual nitrogen, and thus the COD removal effect is significantly impaired.

Further, when treated water obtained by biologically nitrifying and denitrifying biological wastewater is immediately photooxidized in the presence of a photocatalyst, some substance in the biologically treated water remarkably exerts a photooxidation action in the presence of the photocatalyst. Since it interferes, the photo-oxidation effect is significantly inhibited. On the other hand, when the aggregated treated water obtained by adding an inorganic flocculant to the treated water subjected to biological nitrification and denitrification is further treated with activated carbon, the inhibitor that significantly interferes with the photooxidation action is removed, and It was found that a COD removing effect was obtained. Probably the inhibitor in photo-treated water (for photooxidation in the presence of photocatalyst) is phosphate ion or bicarbonate ion that is aggregated and removed by the inorganic coagulant, or high molecular weight organic substance that is adsorbed and removed by activated carbon treatment. To be done. From the above findings, in order to effectively perform the photooxidation effect of irradiating with light in the presence of a photocatalyst, human wastewater is denitrified by biological nitrification and denitrification to remove ammoniacal nitrogen, and then aggregated. It has been found that it is important to use treated water that has been treated and treated with activated carbon adsorption.

Further, according to the experiments conducted by the present inventors, the human wastewater was denitrified by biological nitrification and denitrification to remove ammoniacal nitrogen, and was further retained in the treated water after coagulation and activated carbon adsorption. It was found that the COD removal rate by photooxidation effected by irradiation with light in the presence of a photocatalyst of the COD component was considerably high, and that the COD was completely removed by a contact time of several hours. An ultraviolet irradiation lamp is suitable as a light source for light irradiation, but since the cost such as power consumption and lamp replacement cost is large, in order to perform this treatment at the lowest possible cost, the water to be treated is placed in the photooxidation tank. A method of injecting, irradiating the surface of the water to be treated with sun rays during the day, and irradiating with artificial rays only at night is preferable. For example, on the roof of a night soil treatment facility,
Alternatively, a water channel is provided outdoors so that the activated carbon-treated water can stay for several hours while irradiating sunlight to allow the photocatalytic reaction to proceed. If the water depth of the pond is too deep, the irradiation of sunlight will be insufficient. Further, if a large amount of dilution water is added to human waste-based wastewater for biological treatment, the capacity of the photocatalytic reaction tank becomes too large and it becomes difficult to carry out the biological treatment.

As the shape of the photocatalyst, there can be used known ones such as fine particles, those having a photocatalyst attached to a granular carrier, and those having a photocatalyst attached to the surface of a plate-like or rod-like material. When the photocatalyst is immobilized on the carrier, the surface area of the photocatalyst may be reduced and the reaction rate may be reduced. In that case, use the photocatalyst as it is suspended in water as fine particles having a particle size of 0.1 to 3 μm. Good to do. It is preferable that the photocatalyst fine particles are separated and collected by a solid-liquid separation means such as aggregation / precipitation, filtration, or filtration with a UF membrane, and reused. The suspension concentration of the particulate photocatalyst may be about 1000 to 5000 mg / liter. Almost no deterioration of the photocatalyst with time is observed, but for safety, it is preferable to be able to supply about 10% per year.

[0014]

【Example】

Example 1 Treated water obtained by biologically nitrifying and denitrifying human sewage undiluted (hereinafter simply referred to as “biological treated water”) was collected from a facility in F City, Shizuoka Prefecture, and the treatment method of the present invention was performed using the treatment apparatus of the present invention. According to the test, the effect of the present invention was verified. That is, C
Ferric chloride (1500 mg / liter) was added to water-treated biologically-treated water having an OD of 330 mg / liter and a chromaticity of 1800 to perform coagulation separation to obtain coagulation-separated water having a COD value of 62 mg / liter. Further, the coagulated and separated water is treated with activated carbon to obtain COD.
Activated carbon-treated water having a value of 12 mg / liter was obtained. Titanium oxide photocatalyst [Product of Fuji Titanium Co., Ltd.]
3000 mg / liter was added and suspended in activated carbon-treated water and allowed to stay for 3 hours while aerating in a tank with a water depth of 50 cm installed outdoors during fine weather in summer, and then a UF membrane with a nominal molecular weight cutoff of 10000 [Nitto Denko Titanium oxide photocatalyst fine particles were separated according to the method of manufactured by K.K. The quality of this membrane permeate is CO
The D value was 0 mg / liter and the chromaticity was zero.

Further, when the coagulated and separated water was treated with SV2 through a granular activated carbon adsorption tower for treatment, COD of the activated carbon treated water after 20 days deteriorated to 18 mg / liter.
Since this COD is worse than the standard COD of discharged water of 15 mg / liter or less, it means that the activated carbon needs to be regenerated every 20 days. On the other hand, when the activated carbon-treated water was subjected to the photocatalytic oxidation treatment, after passing through the granular activated carbon adsorption tower for 55 days, the COD of the activated carbon-treated water was 31 mg / liter at this point.
The OD was 12 mg / liter, which was a value equal to or lower than the discharged water quality standard. Therefore, according to the present invention, the regeneration frequency of activated carbon can be reduced to about 1/3.

Comparative Example 1 A titanium oxide photocatalyst was added at 3000 mg / liter directly to the water-treated biologically treated water having a COD of 330 mg / liter and a phosphate ion concentration of 432 mg / liter as in Example 1,
When the weather is fine in the summer, the CO of the membrane permeated water that has been separated by membrane after aeration for 3 days while aerating in a tank with a water depth of 50 cm installed outdoors
D was measured. The COD value of the membrane permeated water was 195 mg / liter, and the COD removal rate was small. It can be seen that it is important to add a flocculant to the biologically treated water before the photooxidation treatment, to perform the coagulation separation treatment, the activated carbon adsorption treatment, and then the photooxidation treatment.

Comparative Example 2 Inorganic flocculant was added to biologically treated water of water quality of COD of 330 mg / liter and phosphate ion concentration of 432 mg / liter of Example 1 to produce floc, and the flocculated water was subjected to membrane separation. 3000mg of titanium oxide photocatalyst
The COD of the membrane permeated water after addition of 1 / liter of the permeated water was 15 mg / liter after being allowed to stay for 1 day while aerating in a tank with a water depth of 50 cm installed outdoors during fine weather in the summer, a value that is barely satisfying the COD standard for discharged water. However, the residence time in the photocatalytic oxidation tank was too long to be practical. Therefore, it is recognized that it is important to subject the coagulated treated water to the activated carbon adsorption treatment and the activated carbon treated water to the photooxidation treatment.

[0018]

【The invention's effect】

1. COD, which was impossible in the past, is zero or close to zero,
It is possible to obtain discharged water with a very small amount of COD components. 2. The regeneration frequency of the activated carbon used for the activated carbon adsorption treatment can be greatly reduced. 3. By subjecting the biologically treated water to an aggregating treatment with an inorganic aggregating agent and an adsorbing treatment with an activated carbon, it is possible to remove a substance that interferes with the photocatalytic oxidation action, and it is possible to efficiently exhibit the photocatalytic oxidation action.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a device configuration and a treatment process of human waste system wastewater treatment of the present invention.

[Explanation of symbols]

1 denitrification tank 2 Nitrification tank 3 membrane separator 4 coagulation separation tank 5 membrane separator 6 Activated carbon treatment tank 7 Photo-oxidation tank 8 night soil sewage 9 Biologically treated separated water 10 Coagulation separation water 11 Flocculant 12 Discharged water

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C02F 9/00 504 C02F 9/00 504A 1/28 ZAB 1/28 ZABD 1/32 ZAB 1/32 ZAB 1/52 ZAB 1 / 52 ZABE 3/34 101 3/34 101A 101B (56) Reference JP-A-9-10799 (JP, A) JP-A-9-10797 (JP, A) JP-A-2-172597 (JP, A) Kai 63-214398 (JP, A) JP-A-57-10393 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 9/00 502 C02F 3/34 101

Claims (2)

(57) [Claims] 1. A method of biologically nitrifying and denitrifying human waste sewage, coagulating and separating it with an inorganic coagulant, treating the separated water with activated carbon, and irradiating the activated carbon-treated water with a photocatalyst for irradiation. Advanced treatment method for sewage system wastewater. 2. A biological sewage treatment apparatus comprising at least a biological nitrification denitrification treatment device comprising a denitrification tank and a nitrification tank, a coagulation separation tank and an activated carbon treatment tank, wherein a photocatalyst is provided after the activated carbon treatment tank. The human waste sewage treatment apparatus, which is provided with a photocatalytic oxidation unit that irradiates light in the presence of the.