JPH06170393A - High-degree purification device of organic sewage - Google Patents

Abstract

PURPOSE:To provide a compact nitrification and denitrification treatment apparatus capable of efficiently performing nitrification and denitrification treatment using a single treatment tank, reduced in washing frequency and capable of being simply washed. CONSTITUTION:In a high-degree purification device of org. sewage, an upstream fixed bed A, a downstream upper fixed bed B and a downstream lower fixed bed D are arranged through a partition wall C and a porous member is provided to the lower part of the device and an air diffusion member aerating at least the fixed bed B is provided and raw water is supplied to the fixed bed A from the raw water supply pipe 2 provided to the lower part of the fixed bed A to be upwardly passed through the fixed bed A and overflows the partition wall C at the upper part of the device to flow in the fixed bed B to be successively passed through the fixed beds B, D as a descending stream and a means refluxing a part of the outflow water from the fixed bed D to the fixed bed A and a means allowing the other part of the outflow water to flow out as treated water are provided to the lower part of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment apparatus for highly biologically purifying organic wastewater containing ammoniacal nitrogen.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, two treatment tanks having an immersion fixed filter bed filled with a filter material of granular minerals such as anthracite are used, and raw water is supplied from a raw water supply pipe 19 to the first tank. The denitrifying filter bed 20 in which the denitrifying bacteria are retained in the filter medium is used as the denitrifying filter bed 20 and the nitrifying bacteria are retained in the filter medium as the nitrifying filter bed 21 in the second treatment tank. 20 and the nitrification filter bed 21 are arranged in series, and denitrification treated water obtained by passing the denitrification filter bed 20 in a downward flow is introduced from the upper part of the nitrification filter bed 21 through a circulation pipe 31. Air is blown from the air diffusing pipe 22 at the lower part of the filter bed to aerobically nitrify it in the nitrification filter bed 21, and the outflow water (referred to as nitrification solution) is once stored in the treated water tank 23 and then degassed by the pump 30. Biological nitrification and denitration in a configuration using two immersed fixed filters circulating in the nitrogen filter 20. Arsenide devices are known.

However, this conventional technique has the following drawbacks, and the development of a more excellent technique has been earnestly desired. Organic wastewater containing SS flows into the denitrification filter bed 20, but the filter bed is clogged quickly, and the filter bed must be frequently washed. As a result, the consumption of washing water,
A large amount of cleaning wastewater is generated. There is an inconvenience that the denitrification filter bed 20 and the nitrification filter bed 21 must be separately washed. In addition, the amount of cleaning wastewater generated will increase. Since the nitrification reaction rate and denitrification reaction rate are small, the reaction tank is large, and construction cost and installation space are large. The removal rate of COD and chromaticity is extremely low. Therefore, there is a demand for a compact apparatus that can perform nitrification denitrification treatment, COD, and chromaticity removal with higher efficiency and stability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a new technique capable of solving all of the above-mentioned disadvantages (1) to (3). That is, 1) SS, BOD, nitrification and denitrification, COD, and chromaticity removal can be performed in a single tank. 2) Streamline filter bed cleaning. 3) Reduce filter bed blockage and significantly reduce filter bed wash frequency. 4) Remarkably improve the nitrification reaction and denitrification reaction rate. 5) The first settling tank is unnecessary. An object is to provide a compact device having the above functions.

[0005]

The above object can be achieved by the invention of the advanced purification apparatus for organic wastewater according to the present invention. That is, through the partition wall, the granular material having a three-dimensional network structure is packed on the upstream side, the fixed bed A for biological denitrification, and the granular material having a three-dimensional network structure is packed on the upper part of the downstream side, A fixed bed B for performing biological nitrification under aeration of oxygen-containing gas, a fixed bed D for removing COD by filling granular activated carbon at the bottom, and an air diffusion member for aerating at least the fixed bed B are provided. Raw water containing ammoniacal nitrogen is supplied from a raw water supply pipe provided in the lower part of the fixed bed A, the fixed bed A is passed through in an upward flow, and it flows into the fixed bed B over the partition wall in the upper part of the device, A means for passing the fixed bed B and the fixed bed D in a downward flow in order, and a part of the water discharged from the fixed bed D is returned to the fixed bed A at the lower part of the apparatus, and the other part is discharged as treated water. Means are provided at the top of the device to discharge the cleaning wastewater of the device. A highly purifying apparatus.

A specific example of the present invention is shown in FIG. 1, and a specific configuration of the present invention will be described with reference to the drawing. However, the present invention is not limited by the following description. In FIG. 1, a fixed bed A made up of a packed bed filled with a filter medium made of a granular material having a three-dimensional network structure and a partition wall C are provided in the treatment tank 1 of the present invention, and the granular material also has a three-dimensional network structure. A fixed bed B composed of a packed bed filled with a filter medium composed of Further, a fixed bed D of granular activated carbon is provided below it. The fixed bed A is an area for biological denitrification and filtration of raw water, and is also an area for BOD treatment. The fixed bed B mainly performs biological nitrification and advanced filtration of SS, and the fixed bed D is an area where high nitrification, COD and chromaticity removal are performed.

Organic wastewater (hereinafter referred to as raw water) 17 containing ammonia nitrogen, such as sewage, flows into the lower part of the fixed bed A of the treatment tank 1 through the raw water supply pipe 2 and passes through the fixed bed A as an upward flow. The fixed beds B and D enter the denitrified liquid outflow portion 3 at the upper part, and the fixed beds B and D are passed as a downward flow, and outflows from the treated water outflow pipe 14 as treated water 15. In addition, part of the treated water (nitrifying circulating liquid) 16 enters the raw water supply pipe 2 and the raw water 17
Mix and circulate. On the upper part of the fixed bed A, there is provided a grating (lattice) 4 which covers the upper part of the fixed bed A to prevent the filling filter medium from flowing out, and on the lower part of the fixed bed B, the fixed bed B is filled. Gratings (lattice) 6 are stretched to prevent the filter material from falling. 5 is a grating provided under the fixed beds A and D to prevent the filter medium from falling. This can be appropriately selected by omitting a part or all of it depending on the conditions, or by providing an arbitrary support floor instead of the grating, and the positions of the following air washing pipe 10 and air diffuser pipe 7 are also appropriately inside, above or below the support floor. Can be set.

Further, an air washing pipe 10 for air-washing the fixed bed A is provided in the lower part of the fixed tank A in the lower part of the treatment tank 1, and an air diffusing pipe 11 is further provided in the fixed bed A. There is. Below the fixed bed D, an air diffuser 7 is provided for supplying oxygen to the microorganisms held in the packing materials of the fixed beds B and D. Reference numeral 18 is a wash drain outlet, and 19 is a valve. The oxygen-containing gas to be sent to the air diffuser 7 is sent from the blower 9 via the gas supply pipe 8, and the air washing pipes 10 and 11 are supplied with air from the blower 13 via the air supply pipe 12. Here, the air washing pipe 10 and the air diffusing pipe 11 can be shared by the same member, and the amount of discharged air may be increased during the air washing compared with the normal case.

In any of the processing apparatuses shown in FIG. 1, the granular material having a three-dimensional mesh structure which constitutes the filter medium filled in the fixed bed A and the fixed bed B has continuous holes from the surface to the inside. It can be produced by a known foaming method using known materials such as organic polymers and inorganic compounds. The granular material is not particularly limited as long as it is suitable for the foaming method, but a urethane resin having appropriate elasticity and strength for the material itself is preferable.

As the filter medium, for example, a porous granular material such as polyurethane foam is cut into a desired shape and size before use. The size is 10 to 30 mm, preferably 15 to 2
The shape is 0 mm, and various shapes such as a square shape, a spherical shape, and the like can be taken, but a square shape is preferable. The specific gravity of the material is usually preferably about 1.0 to 1.2. The porosity is 90
% Or more is preferable. Pore size, that is, pore size is 0.1-6
It is desirable to select from the range of mm, preferably 2 to 4 mm. The number of holes per 1 cm length is 5 to 2
0 is preferable. Further, the granular activated carbon in the fixed bed D has a particle size of 2 to
3 mm is suitable.

[0011]

The function of the present invention will be described below. Organic wastewater (raw water) 17 containing ammonia nitrogen, such as sewage, is treated tank 1
Flows into the fixed bed A from the lower part of the tank and flows through the fixed bed A as an upward flow together with the nitrifying circulating liquid 16. Since the filter medium composed of the granular material having a three-dimensional network structure packed in the fixed bed A has a high concentration of denitrifying bacteria of 15,000 to 18,000 mg / liter (actual measurement value) immobilized in the network structure, NO _X in the nitrified circulating liquid 16 using the BOD in the raw water
-Reduce N (nitrate nitrogen) to N ₂ . The reaction performed by this denitrifying bacterium is represented by the following formula. BOD + NO _X −−−−− → N ₂ + CO ₂ + H ₂ O (denitrifying bacteria) Note that a small amount of gas such as air may be constantly discharged from the air washing pipe 10 to perform aerobic denitrification. ₂
It is also preferable because the gas can be easily expelled. Further, it is important to constantly aerate the air from the air diffusing tube 11 to remove the residual BOD in the A layer above the air diffusing tube 11. Otherwise, when the denitrification reaction deteriorates, a large amount of BOD flows into the nitrification section B, and the nitrification reaction is hindered.

Further, as described above, the air washing pipe 10 and the air diffusing pipe 11
Can be used together. Since the filter medium composed of the three-dimensional mesh-like granular material that constitutes the fixed bed A is also excellent in the filtration performance of SS, SS in the raw water is filtered and removed by passing through the fixed bed A, The SS of the effluent is usually lower than 5 mg / liter. When the above-mentioned polyurethane foam granules are used as the three-dimensional mesh granules, and particularly preferably the polyurethane foam granules having a specific gravity of about 1.1 to 1.2 are used, N ₂ gas generated by the denitrification reaction is generated. As a result of the CO ₂ gas bubbles being trapped in the network structure of polyurethane foam, the apparent specific gravity becomes 1.0 or less, and the fixed bed A is formed below the porous member as a floating packed layer.

Thus, fixed bed A from which most of BOD and SS in raw water and NO _X -N in circulating nitrification solution was removed
The effluent from the water enters fixed beds B and D where the biological nitrification reaction proceeds. Since the nitrifying bacteria are immobilized at a high concentration inside and on the surface of the three-dimensional network granules and granular activated carbon constituting the fixed beds B and D, NH _{3 in} the raw water is fixed.
-N is nitrified at a high speed by the reaction of NH ₃ -N + oxygen ----- → NO _X -N (nitrifying bacteria), COD,
The chromaticity is also removed by the action of the activated carbon on the fixed bed D and the organisms adhering to the activated carbon, and SS is also filtered and removed, and the treated water 15 becomes extremely clear treated water 15 and flows out of the system. The fixed bed B also has an apparent specific gravity smaller than that of water due to air bubbles trapped in the polyurethane foam granular filter medium, and forms a floating layer.

According to the present invention, a filter medium composed of three-dimensional mesh-like particles is specified and used as a filter medium to be packed in the fixed bed A, and the denitrifying bacteria and the like have a much higher concentration (4 to 5) than the conventional filter medium. It is important that the fixed bed D of granular activated carbon is provided after the nitrification section B.

The particular structure is important, and even if the dissolved oxygen concentration in the circulating nitrification solution is high, the denitrification reaction proceeds in the fixed bed A without problems. This is because, in the interior of the filter material made of cubic-mesh shape of the particulate solid because dissolved oxygen is less likely to diffuse, denitrification is difficult advances the NO _X -N inside the filter material. Further, since the fixed bed filled with the three-dimensional mesh-like particles has a large SS trapping capacity, it is less likely to be clogged and the fixed bed is washed less frequently.

[0016]

[Examples] The effect of the present invention was verified by treating the groundwater of the group through the coarse screen having an opening of 10 mm and treating the raw water having the water quality shown in Table 1 with the treatment apparatus of the present invention. Table 1 (Water quality of raw water) Water temperature: 15 to 18 ° C pH: 7.2 to 7.3 SS: 89 to 163 mg / liter BOD: 120 to 170 mg / liter COD: 36 to 44 mg / liter Total nitrogen: 27 to 35 mg /liter

Table 2 shows the processing conditions. Table 2 (Treatment conditions) Treatment equipment dimensions: Dimensions 0.4 m × 0.8 m square tank with 0.4 m × 0.4 m two tank side-by-side type with height 4.5 m fixed bed A Height 2.0 m Height of fixed bed B 1.0 m Height of fixed bed D 1.0 m Sewage flow rate: 5.76 m ³ / day Filtration rate: 36 m / day Air supply from air diffuser 7: 15 Nm ³ / day Air supply amount from air diffuser 11: 5 Nm ³ / day Nitrification solution circulation amount: 6 m ³ / day The filter medium filled in packed bed A and packed bed B has a particle size of 10 × 25 × 25 mm It is a granular piece of polyurethane foam having an angular shape and 13 cells.

Under the treatment conditions of Table 2, 10 times the sewage of the water quality of Table 1
It was continuously treated for months. Nitrifying bacteria, denitrifying bacteria, and BOD-assimilating bacteria were sufficiently immobilized on the filter material of granular particles of polyurethane foam within 30 days after the start of water flow, so from the 31st day once every day except Saturday and Sunday, 24 hours composite sample Was collected (no sampling on Saturday and Sunday) and water quality analysis was performed. The results are shown in Table 3. Table 3 (Water quality of treated water) pH: 6.8 to 7.0 SS: 1.5 to 2.2 mg / liter BOD: 2 to 3 mg / liter COD: 4.1 to 4.8 mg / liter Total nitrogen : 8.0 to 10.0 mg / liter Chromaticity: 10 or less As apparent from Table 3, SS and BOD, COD,
T-N, clear water with extremely low chromaticity was obtained. Also,
The filter bed may be washed once every 10 to 14 days, and the filtration could be continued for an extremely long time. (The conventional device of FIG. 2 requires cleaning once a day)

[0019]

EFFECTS OF THE INVENTION By treating organic wastewater with the apparatus of the present invention, (1) nitrification and denitrification can be performed at high speed, so the apparatus installation space is small and the filter bed can be reasonably washed. (2) Since nitrifying bacteria and denitrifying bacteria are immobilized at a high concentration on the surface and inside of a filter medium composed of three-dimensional mesh-like particles, the rate of nitrifying reaction and denitrifying reaction is 3 to 4 times that of the conventional method. large. Further, COD can be removed for a long period of time without regenerating the activated carbon, probably because COD-degrading bacteria propagate on the surface of the activated carbon. (3) The filter bed is not significantly clogged and the filter bed cleaning frequency is drastically reduced. Therefore, maintenance is easy and the amount of cleaning wastewater generated is small. (4) Since it is not necessary to first set up a sedimentation tank and sewage with high SS can be directly treated, it can be made more compact. (5) Since the part for removing the residual BOD by the aerobic organism is provided on the upper part of the filter bed A, even if the denitrification reaction is deteriorated, a large amount of BOD flows into the nitrification part to cause the nitrification reaction. Does not make it worse.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a one-tank type biological nitrification / denitrification treatment tank of the present invention.

FIG. 2 is a schematic view showing a typical example of a conventional two-tank type biological nitrification denitrification treatment apparatus.

[Explanation of symbols]

 1 treatment tank 13 blower 2 raw water supply pipe 14 treated water outflow pipe 3 denitrification liquid outflow part 15 cleaning water 4 grating 16 nitrification circulating liquid 5 grating 17 raw water 6 grating 18 cleaning drainage outlet 7 diffuser pipe 19 valve 8 gas supply pipe A Fixed bed 9 Blower B Fixed bed 10 Air-washing diffusing pipe C Partition wall 11 Diffusing pipe D Fixed bed 12 Air supply pipe

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C02F 9/00 ZAB A 7446-4D

Claims (1)

[Claims] 1. A fixed bed A in which a granular material having a three-dimensional network structure is filled on the upstream side through a partition wall to perform biological denitrification, and a granular material having a three-dimensional network structure is provided on the upper side of the downstream side. A diffusing member for aerating at least the fixed bed B, which is provided with a fixed bed B for performing biological nitrification under the diffusion of oxygen-containing gas and a fixed bed D for removing COD by filling granular activated carbon at the bottom. Is installed and raw water containing ammoniacal nitrogen is supplied from a raw water supply pipe provided in the lower part of the fixed bed A, the fixed bed A is allowed to flow in an upward flow, and the upper part of the apparatus crosses the partition wall to the fixed bed B. Inflow,
A means for passing the fixed bed B and the fixed bed D in a downward flow in order, and a part of the water discharged from the fixed bed D is returned to the fixed bed A at the lower part of the apparatus, and the other part is discharged as treated water. An advanced purification device for organic sewage, characterized in that means is provided at the upper part of the device to discharge the cleaning wastewater of the device.