JPH0240292A - Apparatus for anaerobically treating upward flow - Google Patents

Abstract

PURPOSE:To eliminate a dead space of a flow of raw water and to increase the rate of effective utilization of microorganisms by making the bottom of an anaerobic reaction vessel rugged and arranging raw water inflow holes at the valley parts of the rugged bottom CONSTITUTION:Blocks 10 having a triangular cross-section are arranged on both sides of each raw water inflow pipe 4 laid on the bottom. of an anaerobic reaction vessel 1 along the longitudinal direction of the pipe 4. Raw water flowing in the vessel 1 is guided upward along the slopes of the blocks 10. The angle of inclination of the slopes is regulated to 20-60 deg.. Plural raw water inflow holes have been pierced in the pipe 4 at regular intervals in the longitudinal direction so as to cover 0.5-1.0m<2> area per one hole. By this constitution, the formation of a dead space in a sludge bed at the lower part of the vessel 1 is prevented, anaerobic microorganisms are allowed to work in the entire bed and the rate of effective utilization of the microorganisms is increased.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an upflow anaerobic treatment device, and more specifically, an upflow anaerobic treatment device having a structure devised to enable efficient use of anaerobic microorganisms. The present invention relates to a countercurrent anaerobic treatment device.

(Prior art) Upflow anaerobic treatment equipment has been conventionally known as equipment for treating highly concentrated organic wastewater in industrial fields such as the food industry, fermentation industry, pulp and paper industry, and chemical industry. .

FIG. 4 shows a typical example of a conventional upstream anaerobic treatment device (hereinafter abbreviated as UASB). Its structure is such that a plurality of raw water inflow pipes 4 are inserted horizontally at appropriate intervals into a reaction tank (processing tank) 1, which is usually constructed in the shape of a rectangular pool out of concrete or the like, at a position slightly higher than the bottom plate 7. A sludge bed 2, which is a layer of anaerobic microorganisms called a so-called granulation granule, is placed in a fixed manner hanging down vertically from above, and is formed at a position sufficiently higher than the raw water inflow pipe 4. Wastewater containing a high concentration of organic matter is introduced from the inflow pipe 4, and through contact and reaction with the anaerobic microorganisms in the sludge bed 2, most of the organic matter in the raw water is converted into generated gas mainly consisting of methane gas and carbon dioxide gas. The upper part of the sludge bed 2 is filled with gas and
A separation mechanism 3 called a solid separator is provided to collect generated gas 8 and guide it to the outside through a gas line 6 for use as an energy source for an appropriate combustion device, etc., and most of the floating solids are recovered. The treated water is discharged outside the system through a treated water pipe 5 using an overflow method or the like.

Although IIAsB, which has such a structure, exhibits excellent functionality in treating wastewater containing high concentrations of organic matter (for example, 1000 mg/1 or more as BOD), the rate of decomposition of organic matter by anaerobic microorganisms is not that fast. It is also known that the growth of anaerobic microorganisms is not very fast, and therefore the amount of treatment per reactor capacity (therefore, the flow rate of raw water inflow) cannot be made very large.

In addition, the actual UASB equipment usually has a wide bottom surface area of 10 to several thousand square meters, and whether the raw water inflow pipe is installed horizontally or vertically, it is difficult to install the raw water inlet pipe per the capacity of the reaction tank. Because the throughput is not large, it is not possible to arrange the arrangement very closely, and in general, each pipe inlet has a density of 0.5 to 1. They are usually designed and constructed to cover an area of approximately 1.5 cm.

(Problems to be Solved by the Invention) By the way, when the inventors of the present invention repeatedly considered improving the performance of the above-mentioned IIAsB actual device, it was discovered that there were the following problems that should be improved. . That is, I
As mentioned above, actual IAsB equipment is designed and constructed so that each raw water inlet generally covers an area of about 0.5 to 1.0 rn' or more. This is thought to be due to this, but a dead space is created in the middle area between the many raw water inlets where there is virtually no flow of raw water, which reduces the efficiency of the equipment as a whole or prolongs the initial operation of the equipment. This results in the problem of prolongation of the transition period from the so-called start-up to the steady state.

At first glance, it seems that such problems can be solved by, for example, arranging raw water inlets at a high density or increasing the speed of raw water inflow, but in reality it is not that simple. For example, increasing the density of raw water inlets can be done by Not only does this complicate the process, but also because the processing capacity of the entire reaction tank cannot be increased, the amount of raw water flowing into each location decreases inversely, resulting in no substantial improvement. Furthermore, reducing the inlet port to increase the speed of raw water inflow, for example, has its own limits when considering clogging, since the target of treatment is raw water that contains a high concentration of organic matter. This is not a countermeasure.

FIG. 5 is a diagram schematically showing how such a dead space 9 appears. This dead space 9 is not considered to be very large in terms of volume considering the total volume of the sludge bed 2, but since microorganisms are deposited in this part and compacted, the concentration of microorganisms is higher than in other parts (5 It is estimated that it is more than twice as large.
Therefore, it is thought that the proportion of anaerobic microorganisms that cannot be used for decomposition of raw water is larger than it appears, and its inefficient effect is not necessarily small.

The inventors of the present invention have developed the present invention after repeated studies to solve the problems of the conventional device as described above. The purpose of the present invention is to provide tlAsB, which can be expected to have an extremely excellent effect of effectively eliminating anaerobic microorganisms and effectively utilizing anaerobic microorganisms.

Another object of the present invention is to eliminate the dead space that exists in conventional equipment, thereby making it possible to reduce the amount of seed sludge that must be immersed in the initial stage of the equipment, which makes it possible to secure seed sludge, which is normally difficult to secure in large quantities. It's about reducing the burden.

Still another object of the present invention is to provide a UASB that achieves improved processing capacity by effectively utilizing anaerobic microorganisms.

(Means for Solving the Problems) Therefore, the feature of the upflow anaerobic treatment device (UASB) according to the present invention, which was made to achieve the above object, is that each of the plurality of raw water inlets is It is located in the troughs of the uneven bottom plate of the anaerobic reaction tank.

In IIAsB of the present invention, the unevenness on the bottom of the reaction tank may be formed integrally at the same time as the reaction tank is constructed, or an appropriate triangular pyramid, one cone, etc. may be formed at a predetermined position after the reaction tank is constructed. It may also be of a type in which shaped blocks are placed. The shape of the unevenness may be as long as it is necessary and sufficient to eliminate the above-mentioned dead space. It may be of a type in which an inverted mountain-shaped groove is formed, and the type is not particularly limited. Generally, in consideration of the flow behavior of the raw water flowing out from the raw water flow pipe, the pipe is installed so as to exclude the presence of anaerobic microorganisms within a range that is not affected by the flow of the raw water.

The shape and arrangement of the raw water inlet located in the valleys of the unevenness may be formed in accordance with those of the raw water inlet pipe and raw water inlet in the conventional 1IAs8.

The apparatus subject to the present invention is applied on the necessary and sufficient condition that it is an upward flow type apparatus that utilizes anaerobic microorganisms, in which raw water is introduced from the lower part of the reaction tank. Examples include an upflow anaerobic treatment device in a narrow sense that decomposes organic matter into methane and the like, an upflow type denitrification device, and the like.

(Function) By having the above-described configuration, the present invention structurally eliminates the dead space that is conventionally formed on the bottom plate, where there is substantially no activity of anaerobic microorganisms, and the sludge bed in the reaction tank is completely reduced. Used efficiently.

(Example) The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 shows an example of the structure of a UASB reaction tank to which the present invention is applied and the arrangement of raw water inflow pipes. A plurality of raw water inflow pipes 4 are inserted into the reaction tank from the horizontal sides of the lower part of the frame at a constant height from the bottom plate 9 and in parallel at regular intervals.

This raw water inlet pipe 4 has raw water inlets opened at appropriate intervals in the longitudinal direction, and each raw water inlet has approximately 0.5 to 1
．． It is provided so as to cover an area of about Orn'.

The feature of this example is that blocks 1O having a chevron-shaped cross section are installed on both sides of the plural raw water inflow pipes 4 along the longitudinal direction of the inflow pipes, and the inflow raw water flows onto the slopes of the chevron-shaped blocks 10. It is located in such a way that the distribution is guided upwards along the coast.

In such a configuration, it is often appropriate to select the inclination angle of the slope of the chevron-shaped block 1o generally within a range of about 20 to 80'. This is because if the angle of inclination is less than 20 degrees, there is a risk that the dead space will be formed on this slope, and the effect of installing the blocks cannot be expected to be sufficient. Furthermore, since the angle of repose of anaerobic sludge is usually around 50°, even if the angle of inclination of the installation block is 60° or more, this tends to limit the area where anaerobic microorganisms exist that can be effectively utilized.

FIG. 2 shows an example of the structure of a reaction tank and the arrangement of raw water inflow pipes in a UASB with another configuration. In this example, the raw water inflow pipe 34 is vertically suspended from above the reaction tank 31. This figure shows a case where the present invention is applied to a UASB of the same type. The raw water inlet in this example is configured by forming a plurality (for example, five) nozzles radially at the lower end of the raw water inlet pipe 34, as shown in FIG. 2(C).

In this example, the block for removing the so-called dead space has multiple raw water inlets, considering that raw water flows in radially from the lower end of the raw water inlet pipe as shown in Fig. 2(a). A conical block 35 is placed at the farthest point from the groin, and a semi-conical block 36 is placed in contact with the side wall. It is formed as a square triangular pyramid block 37.

Example 1 The bottom surface dimensions shown in FIGS. 3(a) to (c) are 2 x 2 m.

In the reaction tank 1 with an effective height of 4 m, L = 12 on the plane
Raw water inlet pipes 4 are placed at four locations with J2 = 400mm (installation height from the bottom plate: io).

mm) L/, also shown on the bottom plate 9 T = 700m
m.

t 1 = 500mm, t 2 = 150mm
, a chevron-shaped block 10 having dimensions of an inclination angle θ=406 was installed.

Anaerobic sludge (M
LS518,000 mg/1) was added for 6 rn', and the inside of the reaction tank was kept at 35° C., and raw water was introduced to carry out the treatment. The inflow raw water used was synthetic wastewater whose main component was a mixture of glucose and monosodium glutamate at a ratio of 2=1, and which was adjusted to a raw water BOD of 5000 mg/IL by adding nitrogen, phosphorus, etc.

For comparison, a reaction tank of a comparative example having the same configuration was provided except that the chevron-shaped block 39 was not installed and the bottom plate was made flat.

For the reaction vessels of these examples and comparative examples, operation was started in 7 days with a BOD volume load of 0.5 kgBOD/rn'', and thereafter the load was increased by 20 zero every week to finally reach 5 kgBOD/rn''. /day load.

When we investigated the state of the sludge in the reaction tank about half a month after the start of operation, we found that in the reaction tank of the comparative example, there were five dead spaces above the bottom plate, and the amount of sludge in these dead spaces was about the same as the amount of seed sludge input. It took up half of the amount. After that, the quality of the treated water from the reaction tank of the comparative example deteriorated, and it was reduced to 1.5 kg BOD/
It was virtually impossible to increase the load to rn''/8 or higher.

The dead space was determined and the amount of sludge in the dead space was calculated as follows.

Determination of dead space: A sampler was inserted from the top of the reaction tank and the sludge concentration at each position at the bottom of the reaction tank was measured. Dead space is determined when the sludge is tar-like and the sludge concentration is 30,000 mg/fL.
The above area was defined as dead space.

Calculation of sludge volume: (Dead space volume based on the above sampling results) ×
(average sludge concentration in the dead space) was defined as the sludge concentration in the dead space.

On the other hand, in the reaction tank of the example, virtually no dead space formation was observed, and the load continued to increase with good treated water quality, reaching 5 kgBOD/rri after about 2 months.
″/day load was allowed.

(Effects of the Invention) As described above, IIAS8 according to the present invention can substantially eliminate the dead space for anaerobic microorganisms where raw water does not flow through a simple structural improvement of making the bottom of the reaction tank uneven. This can be expected to have the extremely excellent effect of making the use of anaerobic microorganisms more effective.

In addition, by eliminating the dead space that exists in conventional equipment, it is possible to reduce the amount of seed sludge that must be input at the initial stage of the equipment, and it has the effect of reducing the burden of securing seed sludge, which is normally difficult to secure in large quantities. There is also.

Furthermore, effective use of anaerobic microorganisms has the effect of improving the raw water treatment capacity of the device.

[Brief explanation of the drawing]

Fig. 1(a) is a plan view showing an outline of the configuration of the bottom plate of the reaction tank of the upflow anaerobic treatment device to which the present invention is applied (horizontal insertion type of raw water inflow pipe), and Fig. 1(b) ) is a longitudinal front view of the same, FIG. 2(a) is a plan view of another example (vertical hanging type of raw water inflow pipe), and FIG. 2(b) is a plan view of the reaction tank in FIG.
The longitudinal cross-sectional view along the line, FIG. 2(c), is an enlarged view of the raw water inlet pipe portion. FIGS. 3(a), 3(b), and 3(c) are diagrams for explaining the structure of the bottom plate portion for explaining the general configuration of the reaction tank used in the test of the present invention. FIG. 4 is a diagram showing an outline of the configuration of a conventional upflow anaerobic treatment apparatus, and FIG. 5 is a diagram for explaining the state of dead space that occurs in the conventional apparatus. 1: Reaction M 2: Sludge bed 3: Separation mechanism 4: Raw water inflow pipe 5: Treated water pipe 6: Gas line 7: Bottom plate 8: Generated gas 9: Dead space 1O: Mountain-shaped block 31: Reaction 34: Raw water inflow pipe 35: Conical block 36: Half-conical block 37: Triangular pyramidal block Fig. 1 (α) Fig. 4

Claims (1)

[Claims] 1. An upflow anaerobic treatment device characterized in that the raw water inlet is arranged in the valley of the uneven bottom plate of the anaerobic reaction tank formed in the uneven shape.