JPH07299500A - Production of inorganic flocculant-mixed sludge and device therefor - Google Patents

Abstract

PURPOSE:To provide a method and device capable of directly mixing the powder of an inorganic flocculant such as slaked lime, quick lime with a sludge without using water. CONSTITUTION:The inorganic flocculant powder introduced from a storage tank 1 of the inorganic flocculant powder is supplied to the center part of an ejector type or a line mixer type mixer 3 and the flowable sludge introduced from a sludge storage tank 2 is supplied from the periphery of the mixer 3 and both are directly mixed. The cost for city water is reduced since water for previously dissolving the inorganic flocculant powder is unnecessary and the load of a dehydrator is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for producing an inorganic coagulant-mixed sludge used in a sewage treatment plant.

[0002]

2. Description of the Related Art At a sewage treatment plant, sewage sludge is mixed with an inorganic coagulant such as slaked lime or quick lime and then sent to a dehydrator for dehydration treatment. It was usual that such an inorganic coagulant was dissolved in water in advance and introduced into a mixing tank to be mixed with sludge. However, such a conventional technique has the following problems.

First, a large amount of water is required to dissolve the inorganic coagulant. Secondly, if the inorganic coagulant dissolved in water is not constantly stirred, it tends to settle, and the injected concentration varies. Thirdly, the load on the dehydrator is increased by the amount of dissolved water, and the swallowing amount of sludge is reduced. Fourth, the volume of the mixing tank increases by the amount of the dissolved water. Fifth, the inorganic coagulant is easily deposited in the pipe, and the pipe is easily blocked.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, eliminates the dissolved water for dissolving the inorganic coagulant, and makes it easier and more economical to prepare an inorganic coagulant-mixed sludge. This is done to provide a method and apparatus that can be obtained.

[0005]

Means for Solving the Problems The method for producing an inorganic coagulant-mixed sludge of the present invention, which has been made to solve the above-mentioned problems, comprises the steps of mixing an inorganic coagulant powder with an ejector-type or line-mixing-type mixer at the center. The main feature is to supply the sludge with a fluidity from the surroundings and directly mix the both. Further, the apparatus for producing a mixed sludge of inorganic coagulant according to the present invention comprises a storage tank for the inorganic coagulant powder, a sludge storage tank, and a sludge storage tank for supplying the powder of the inorganic coagulant derived from the storage tank for the inorganic coagulant powder and the sludge storage tank. It is characterized by comprising an ejector type or line mixing type mixer which directly supplies the sludge having fluidity derived from the above from its surroundings.

[0006]

According to the present invention, the powder of the inorganic coagulant such as slaked lime or quick lime can be directly mixed with the sludge without using the dissolving water, so that the dissolving water becomes unnecessary and the economical effect is large. The load on the dehydrator is also reduced. In addition, since the powder of the inorganic coagulant is directly mixed with the sludge, the inorganic coagulant does not settle inside the pipe or the like, and the pipe is not clogged. Moreover, since the mixing ratio of the inorganic coagulant can be easily adjusted, the dehydrator can be stably operated.

[0007]

The present invention will be described below in more detail with reference to the illustrated embodiments. 1 and 2 show a first embodiment of the present invention, wherein 1 is a storage tank for inorganic coagulant powder, 2 is a sludge storage tank, 3 is a mixer, 4 is a sludge adjusting tank, 5 is a filter press, etc. It is a dehydrator. Inorganic coagulant powder storage tank 1 stores inorganic coagulant powder such as slaked lime and quicklime.
The sludge storage tank 2 stores fluid sludge having a water content of, for example, about 93 to 98%.

In the first embodiment, the ejector type mixer 3 is used as the mixer 3. This mixer 3 has an angle α of 30 to 60 °, preferably 40 to 50 °, as shown in FIG.
The powder supply nozzle 3b is provided at the center of the tapered main body 3a of
Further, a plurality of sludge supply nozzles 3c are provided around it. Here, the angle α is selected so that adhesion or clogging in the tube is unlikely to occur.

Then, the sludge having fluidity is guided from the sludge storage tank 2 to the sludge supply nozzle 3c of the mixer 3, and at the same time, the inorganic coagulant powder is guided from the storage tank 1 of the inorganic coagulant powder to the powder supply nozzle 3b. Eject inside 3a. Then, the powder of the inorganic coagulant is taken into the sludge ejected from the sludge supply nozzle 3c and stirred, and both are directly and uniformly mixed. The sludge supply amount is controlled by the rotation speed control of the sludge supply pump 15 and the flow control valve 6 based on the signals from the sludge concentration meter 13 and the sludge flow meter 14. Also,
The amount of the inorganic flocculant powder supplied is controlled by a rotary valve or a constant quantity feeder 7. In this way, an inorganic coagulant-mixed sludge in which the sludge and the powder of the inorganic coagulant are directly mixed is produced without using dissolved water.

In the embodiment shown in FIG. 1, the mixer 3 is installed in two stages before and after, and the sludge is mixed with the inorganic coagulant-mixed sludge produced by the mixer 3 in the front stage in the mixer 3 in the rear stage. Has been done. Thus, sludge can be added stepwise to produce an inorganic flocculant-mixed sludge having a desired concentration. On the contrary, a method of introducing the inorganic coagulant mixed sludge produced by the former mixer 3 to the latter mixer 3 and further mixing it with the powder of the inorganic coagulant may be adopted.

In the embodiment shown in FIG. 1, the sludge adjusting tank 4 equipped with a stirrer 8 mixes the inorganic coagulant-mixed sludge thus obtained.
The sludge is further stored in the tank, the sludge is further added through the sludge supply pipe 9 to adjust the concentration, and then the sludge is sent to the dehydrator 5 by the pump 10. When the final concentration adjustment is performed in the sludge adjusting tank 4 in this way, the flocculant concentration of the inorganic flocculant-mixed sludge produced by the mixer 3 is set higher than the target concentration. It is also possible to send directly from the mixer 3 to the dehydrator 5 without performing any operation.

In the dehydrator 5, the inorganic coagulant-mixed sludge mixed with an appropriate amount of inorganic coagulant is dehydrated. It should be noted that the dehydrator 5 is provided with a moisture measuring device 11 and a dehydrating sludge amount measuring device 12 for the obtained dehydrated sludge, and it is possible to control the mixing amount of the inorganic coagulant by feeding back the dehydration condition by these instruments. preferable. Generally, the amount of inorganic coagulant added, such as slaked lime, is 20 to 40% of the solid content in the sludge, so when the water content of the sludge is 95%, the solid content in the sludge becomes 5%. -40% is 1-2%. Therefore, the amount of sludge mixed with inorganic coagulant is 101% if the sludge before addition is 100%.
It will be ~ 102%.

FIGS. 3 and 4 show a second embodiment of the present invention, in which a line mixing type mixer 3 is used. As shown in FIG. 4, this mixer 3 is provided with a spiral blade 3d along a sludge flow direction inside a main body 3a having a powder supply nozzle 3b on the upper part, and a sludge supply nozzle 3c is spirally provided on a side surface of the main body 3a. Like the blade 3d, the blade 3d is inclined. The inclination angle β of this spiral blade 3d is 30-
It is preferably 60 °, more preferably 40 to 50 °.

FIGS. 5 and 6 show a third embodiment in which the line mixing type mixer 3 is used. Here, the mixer 3 is an inverted conical spiral type mixer.
Those with an opening angle γ of ~ 45 ° and a flow angle δ of 10-30 ° are used. The flow angle δ is more preferably 15-20 °.

Also in the above second and third embodiments, the sludge having fluidity supplied from the sludge storage tank 2 is sludge supply nozzle.
The inorganic coagulant powder ejected from 3c and supplied from the tank 1 of the inorganic coagulant powder is ejected from the powder supply nozzle 3b, and both are directly and uniformly mixed inside the main body 3a. The other configurations are similar to those of the first embodiment.

[0016]

As described above, according to the method and apparatus for producing an inorganic coagulant-mixed sludge of the present invention, the powder of the inorganic coagulant such as slaked lime or quick lime is directly mixed with the sludge without using dissolved water. Because it can be done, no dissolved water is needed, and the economic effect of saving the water bill is very large. Further, the load on the dehydrator is reduced, and the amount of sludge swallowed can be increased. In addition, there is no sedimentation of the inorganic coagulant inside the pipe or the like, and there is no risk of the pipe being blocked. Furthermore, claims 2 to 4
By adopting the above method, the concentration of the inorganic coagulant can be controlled more accurately.

[Brief description of drawings]

FIG. 1 is a flow sheet showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing an ejector type mixer of the first embodiment.

FIG. 3 is a flow sheet showing second and third embodiments of the present invention.

FIG. 4 is a sectional view showing a line mixing type mixer according to a second embodiment.

FIG. 5 is a perspective view showing a line mixing type mixer according to a third embodiment.

FIG. 6 is a diagram showing the geometrical shape of a line mixing mixer according to a third embodiment.

[Explanation of symbols]

1 inorganic flocculant powder storage tank, 2 sludge storage tank, 3 mixer, 3a mixer body, 3b powder supply nozzle, 3c sludge supply nozzle, 3d spiral blade, 4 sludge adjusting tank, 5 dehydrator, 6 flow control valve, 7 fixed quantity feeder, 8 stirrer, 9
Sludge supply pipe, 10 pumps, 11 Moisture measuring instrument, 12 Dewatered sludge amount measuring instrument, 13 Sludge concentration meter, 14 Sludge flow meter, 15
Sludge supply pump

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01F 5/04 C02F 11/00 ZAB A

Claims (5)

[Claims] 1. An inorganic coagulant powder is supplied from the central part of an ejector type or line mixing type mixer, and fluid sludge is supplied from the periphery thereof to directly mix the two. Method for producing sludge mixed with inorganic coagulant. 2. An inorganic coagulation characterized in that the sludge mixed with an inorganic coagulant produced by the method of claim 1 is introduced into an ejector-type or line-mixing-type mixer in the subsequent stage and further mixed with a fluid sludge. Method for producing agent-mixed sludge. 3. Inorganic coagulation, wherein the inorganic coagulant-mixed sludge produced by the method of claim 1 is introduced into an ejector-type or line-mixing-type mixer in the subsequent stage and further mixed with the powder of the inorganic coagulant. Method for producing agent-mixed sludge. 4. An inorganic coagulant having a desired concentration by producing an inorganic coagulant-mixed sludge having a high inorganic coagulant concentration by the method of claim 1 and storing the sludge in a sludge adjusting tank and mixing the sludge with the sludge. A method for producing an inorganic coagulant-mixed sludge, which is a mixed sludge. 5. A storage tank for inorganic coagulant powder, and a sludge storage tank,
Inorganic coagulant powder that is introduced from the storage tank of the inorganic coagulant powder is supplied from the center and fluid sludge that is introduced from the sludge storage tank is supplied from the surrounding area to directly mix the two. An apparatus for producing an inorganic coagulant-mixed sludge, comprising: