JPH03278806A - Solid-liquid separation of waste water containing sludge in sewage treatment - Google Patents

Abstract

PURPOSE:To accelerate the settlement of waste water, enhance the efficiency of separation for concn. thereof and facilitate the solid-liquid separation of suspended org. waste water by providing a space part inclined at an angle of 40-80 deg. to the horizontal and the waste liquors contg. sludge are introduced into this inclined space part. CONSTITUTION:A space part inclined at an angle of 40-80 deg. to the horizontal is provided. The waste water contg. sludge are introduced into this inclined space part to separate the sludge therefrom. It is referable that the inclined space part consist of a single or plurality of inclined narrow spaces an that this space part be provided with a plurality of inclined plates separated from one another, in order to permit a simultaneous separation of a large amt. of the sludge. Moreover, the inclined angle of the foregoing inclined plate is made variable and adjustable to the optimum angle according to the concn. and character of the sludge and also the plate can be inclined so as to permit a rapid downstream flow after the sludge settlement. Polyvinyl chloride, polyacrylate, silicone resins, etc., are effective in use as the surface material of the inclined plate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is aimed at reducing the solid concentration of 0.5 generated during sewage sludge treatment.
~5.0% raw sludge, surplus sludge and digested sludge (hereinafter referred to as
When separating solid-liquid (sometimes simply called sludge),
[Conventional technology] Regarding a solid-liquid separation method for suspended organic wastewater that promotes sedimentation and increases the efficiency of separation and concentration. The raw sludge is settled and separated in the first settling tank, the raw sludge is charged to a gravity thickening tank and concentrated, and the thickened sludge is then sent to a digestion tank where it is anaerobically treated. Digestion using bacteria was carried out and the waste was treated as digested sludge.

On the other hand, the supernatant sewage from the first settling tank is led to the aeration tank where activated sludge is added and aerated, and sent to the final settling tank to settle excess sludge, which is then returned to the first settling tank again. The precipitate was charged into the gravity thickening tank together with the raw sludge.

[Problem that the invention seeks to solve]

However, in the conventional sewage treatment process, since the gravity concentration tank is of an upright cylindrical type, there is a problem in that it takes a long time for the raw sludge and excess sludge to settle, resulting in inefficiency.

In addition, the digested sludge discharged from the digestion tank is sent to the dehydration tank via the storage tank, but since the solid concentration of the digested sludge is about 2%, there is almost no sedimentation effect in the storage tank, and it is sent as is to the dehydration tank. Since it contains a large amount of water, dehydration requires time and power, resulting in poor efficiency.

As described above, sludge treatment using conventional methods has a limited treatment capacity because it has to rely on natural settling due to gravity, and social problems arise due to the dramatic increase in the amount of sewage treatment due to population growth and the inflow of rainwater during the rainy season. It had become.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for solid-liquid separation of wastewater containing sludge in sewage treatment, which performs solid-liquid separation of wastewater containing sludge at high speed.

[Means for solving problems]

The solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 1 in accordance with the above object is provided by
An inclined space having an inclination angle of ~80 degrees is provided, and wastewater containing sludge is introduced into the inclined space to separate the solid sludge.

The solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 2 is the method according to claim 1, in which the inclined space portion is composed of one or more inclined elongated spaces.

The solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 3 is the method according to claim 1, wherein the inclined space is partitioned by a plurality of parallel inclined plates. The solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 4 is characterized in that, in the method according to claim 3, the inclined plate is configured so that its angle of inclination can be changed. ing.

The solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 5 is the method according to claim 3, in which the inclined plate is configured to be removable.

Here, the inclined plate is preferably one that has a large contact angle with the sludge droplets precipitated from wastewater, that is, has poor adhesion, and the surface material of the inclined plate is vinyl chloride, polyacrylate,
Silicone resin, Teflon resin, etc. are effective.

The shape of the inclined plate can be a corrugated plate shape that has a large contact area with wastewater, and the inclined plate can be installed uniformly, but discontinuously in a zigzag manner. It is also possible.

[Effect]

In the solid-liquid separation method for wastewater containing sludge in sewage treatment according to claims 1 to 4, when wastewater is placed in an inclined space and left, concentrated sludge is formed on the inclined wall surface or the inclined plate. settles and adheres, forming a precipitate layer on the plate,
The supernatant liquid accumulates in the space between the precipitate layer and the upper wall or partition plate, and the precipitate layer gradually moves to the lower part, so that the precipitate can be recovered.

In the solid-liquid separation method for wastewater containing sludge in sewage treatment described in claim 3, since the inclined space is partitioned by a plurality of parallel inclined plates, a large amount of sludge can be separated simultaneously. be able to.

In the solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 4, since the angle of inclination can be changed, the angle can be changed depending on the concentration and properties of the sludge to obtain the optimum inclination angle. After the sludge has finished settling, the sludge can be quickly flowed to the bottom by further tilting the angle.

In the solid-liquid separation method for wastewater containing sludge in sewage treatment as set forth in claim 5, by removing the inclined plate, the sludge falls to the lower part, and the recovery of the sludge is accelerated.

[Experiment example]

Next, experimental examples conducted to confirm the effects of the present invention will be described.

Here, Fig. 1 is a settling velocity curve of raw sludge in a single layer or multilayer (multi-layer), Fig. 2 is a curve showing the relationship between the slope angle and the depth of the supernatant liquid of digested sludge, and Fig. 3 is a curve showing the relationship between the slope angle and the depth of the supernatant liquid of digested sludge. The figure is a schematic diagram showing the state of installation of the inclined plate used in the multilayer sedimentation experiment.

Experimental Example 1 Polyacrylic acid ester resin sedimentation tube (vertical 1°5c-
× width 4 cm × height 100 cm) was filled with raw sludge at a concentration of 0.51%, and the sedimentation rate corresponding to the inclination angle of the sedimentation tube was measured. The results are shown in FIG. 1 and Tables 1 to 4.

Here, θ is the inclination angle from the horizontal line, Ho and H are the vertical depths of the initial and post-settling part (cm), respectively.
).

Table: 15 minutes Sedimentation time: 30 minutes Table: Sedimentation time: 60 minutes Table: Sedimentation time: 120 minutes As shown in Tables 1 to 4, the angle of inclination θ from the horizontal line is from 906 to 70°, 60° , 45°, the growth rate of the supernatant part becomes faster.

At present (θ・90'), a fixed amount of supernatant is discharged every 60 minutes. When the inclination angle θ=60°, the settling time is only 30 minutes, and the same volume as the above-mentioned current method is produced. Therefore, in the case of θ=60Q, the current 172
The same treatment can be performed with a sedimentation time of . This is a noteworthy result.

Experimental Example 2 Digested sludge (concentration 2.0x) was subjected to single-layer sedimentation in the same manner as in Experimental Example 1, and the depth of the supernatant at a sedimentation time of 24 hours was examined. The results are shown in FIG. 2 and Table 5.

From Table 5, Figure 2 and Table 5, compared to the comparative example θ・90°, θ=
It can be seen that the growth rate of the supernatant at an inclination angle of 45'' to 75° is extremely fast, and an inclination angle of θ=45· to 75° is effective.

Experimental Example 3 The space of the sedimentation layer was divided by five inclined plates made of polyacrylic acid ester as shown in FIG. This container was filled with the raw sludge of Experimental Example 1, and the sedimentation rate was examined at an angle of inclination θ of 45°. The results are shown in Figure 1 (multi-partition layer) and Figure 6.
Table 7 shows the results.

In FIG. 1, it can be seen that the sedimentation speed of multi-layer sedimentation (multi-partition layer) with an inclination angle of 45° is faster than that of single-layer sedimentation with an inclination angle of 45°, and is extremely effective.

Here, old is the vertical depth (C-) of the sedimentation layer in the space No. 1 to N004 separated by each inclined plate in Fig. 3, and St is the per unit width of the sedimentation layer calculated from the old. Volume (cm') , So is the space number, 1 to N
o, the volume per unit width of the initial raw sludge of 4 (cwt'
) [Effects of the Invention] As is clear from the above description, the method for solid-liquid separation of wastewater containing sludge in sewage treatment according to claims 1 to 5 is characterized in that Since wastewater containing sludge is introduced into the system, the solid content of the sludge is rapidly settled, and solid-liquid separation is performed quickly and efficiently.

For example, an existing gravity thickening tank for raw sludge may have an inclination angle of approximately 60 mm.
If an appropriate number of inclined plates are installed, the sedimentation processing capacity will be approximately twice that of the current level, and by changing the angle of the inclined plates, the processing capacity can be further increased.

Therefore, with the solid-liquid separation method for wastewater containing sludge in sewage treatment as set forth in claims 1 to 5, the time for sludge treatment is shortened, less space is required, and as a result, the size of the equipment is reduced. can be achieved. It can also be used in conventional equipment, thereby increasing throughput and, as a result, reducing the amount of expensive flocculant used in conventional methods.

In the solid-liquid separation method for wastewater containing sludge in sewage treatment described in claim 4, by freely changing the inclination angle, it is possible to deal with sludge of various properties, and furthermore, by freely changing the inclination angle, it is possible to deal with sludge of various properties. By changing the angle, the thickened sludge that has adhered to the bottom can be slid to the bottom, collected at the bottom and discharged, and then tilted again at a predetermined angle, thereby accelerating the settling of the sludge.

In the solid-liquid separation method for wastewater containing sludge in sewage treatment as set forth in claim 5, the inclined plate is removable, so that the thickened sludge can be collected in the lower part and easily discharged to the outside. can.

[Brief explanation of the drawing]

Figure 1 is a sedimentation velocity curve of raw sludge in a single layer or multiple layers, Figure 2 is a curve diagram showing the relationship between slope angle and supernatant liquid depth of digested sludge, and Figure 3 is a graph used in a multilayer sedimentation experiment. The installation of the inclined plate is a schematic diagram showing the state.

Claims (5)

[Claims] (1) Sewage treatment characterized by providing an inclined space having an inclination angle of 40 to 80 degrees with respect to the horizontal line, introducing wastewater containing sludge into the inclined space, and separating the solid sludge. Solid-liquid separation method for wastewater containing sludge. (2) A method for solid-liquid separation of wastewater containing sludge in sewage treatment according to claim 1, wherein the inclined space portion comprises one or more inclined elongated spaces. (3) A solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 1, wherein the inclined space is partitioned by a plurality of parallel inclined plates. (4) A solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 3, wherein the inclined plate has a variable inclination angle. (5) A solid-liquid separation method for wastewater containing sludge in sewage treatment according to claim 3, wherein the inclined plate is removable.