JP2010000436A - Method and apparatus for dehydrating organic sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for dehydrating organic sludge by which sludge in a water treatment system is not subjected to concentration variation in a sludge storage tank, sludge treatment performance in planed throughput can be maintained, stable concentration-dehydration treatment can be performed at a fixed chemical pouring ratio, what is necessary is just to perform chemical pouring of substantially treating only sludge fed from a water treatment system, and there is no need of performing new chemical pouring to sludge in a dehydrated and separated liquid. <P>SOLUTION: The method comprises: an incorporation stage where a polymeric flocculant or a polymeric flocculant and a fibrous dehydration assistant are added and incorporated to organic waste water or organic sludge containing suspended matter; a concentration stage where the flocculated sludge produced in the incorporation stage is subjected to concentration treatment, so as to obtain a separated liquid and concentrated sludge; and a dehydration stage where the concentrated sludge obtained in the concentration stage is subjected to dehydration treatment by a screw press 4, so as to obtain a dehydrated cake and a dehydrated and separated liquid, The dehydrated and separated liquid obtained in the dehydration stage is returned to the incorporation stage and/or concentration stage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and apparatus for dewatering organic sludge produced in the course of treatment of organic wastewater such as human waste, sewage sludge and other organic wastewater or sewage, human waste, factory wastewater, and septic tank sludge.

  In general, organic sludge generated in organic wastewater treatment equipment is concentrated and dewatered for sludge reduction and stabilization. For this organic sludge dewatering, a dewatering machine such as a centrifugal dewatering machine, a belt press, a multi-disk dewatering machine, a screw press or the like is generally used. The most suitable one is selected from various dehydrators.

  Of the various dehydrators described above, the screw press useful for dewatering the organic sludge of the present invention is configured by fitting a screw shaft concentrically into a liquid-permeable outer cylinder. The screw press is a continuous dehydrator. It consists of a first half (concentration zone) and a second half (pressing / dehydrating zone) near the sludge supply port, and the dehydrated cake is discharged from the rear end of the outer cylinder. It has become so. In a screw press, sludge is supplied between a screw shaft and an outer cylinder from a sludge supply port, and the screw shaft is rotated to dehydrate the sludge while being squeezed, and the dewatered cake is discharged.

As described above, a general screw press is configured by fitting a screw shaft concentrically in a liquid-permeable outer cylinder, and the space between the cylindrical outer cylinder screen and the screw shaft is supplied with sludge. It narrows from the mouth side toward the sludge outlet side. In the screw press, when the total length of the screen is L (mm) and the inner diameter of the outer cylinder is D (mm), the total length is 4 to 5 times the inner diameter of the outer cylinder, and L = 4D to 5D. In the screw press, since the separated liquid is discharged most from 1D to 2D from the end on the sludge supply port side, this portion is called a concentration zone. A pressing / dehydrating zone is formed following the concentration zone.
The outer screen of the screw press has a large number of apertures, and the aperture area is 0.3 to ¹ mm ^{2. When} the aperture is a perfect circle, the diameter is 0.6 to 1.1 mm. It is.

In the screw press, the amount of separated liquid discharged in the sludge dehydration process is affected by the pressure in the cylinder and the opening diameter of the cylindrical outer cylinder screen. Conventionally, the separation liquid from the cylindrical outer cylinder screen is discharged, but in order to minimize sludge leakage in the entire screw press, particularly in the concentration zone, the opening diameter of the cylindrical outer cylinder screen is 0. 6 mm to 1 mm was employed. The reason for adopting such a hole diameter is that once sludge is leaked, it is discharged as a dewatered cake, that is, the amount of sludge to be processed is reduced and it is difficult to say that it has been efficiently dewatered. Because. Therefore, the sludge recovery rate is generally 95% or more in the entire screw press, and sludge is generally dehydrated in preference to minimizing sludge leakage.
The sludge recovery rate (%) described above is defined as follows.
Sludge recovery rate (%) = (the amount of sludge discharged as dewatered cake / the amount of supplied sludge) x 100 (1)

  Conventionally, when a screw press is used, the sludge is dehydrated without leaking into the separated liquid as much as possible. For this reason, the aperture diameter of the outer cylinder screen of the screw press is true to the aperture. Assuming a circle, a diameter of 1 mm or less is adopted. When the opening diameter of the outer cylinder screen is 1 mm or less, separation of the liquid at the time of sludge dehydration remains insufficient, so the water content of the dewatered cake is 80 to 85% in the case of sewage sludge. It was. Further, it was discharged as a dehydrated cake with a recovery rate of 95% or more of the sludge charged into the dehydrator. That is, since the dewatering performance of the screw press depends on the opening diameter of the outer cylinder screen, it is difficult to increase the sludge recovery rate in the screw press and decrease the moisture content of the dewatered cake with the conventional operation method. there were.

  In addition, in a conventional screw press using a cylindrical screen, a large amount of sludge is mixed in the separation liquid in the concentration zone of the cylindrical outer cylinder screen, and the sludge recovery rate is low. Or the sludge return system which returns to a sludge storage tank is proposed. This sludge return system is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-220598 (Patent Document 1).

That is, Japanese Patent Application Laid-Open No. 9-220598 (Patent Document 1) describes a solid-liquid separation device in which a screw conveyor is installed in the internal space of a cylindrical body. In this solid-liquid separation device, a cylindrical shape is described. A first saucer for receiving moisture separated from the sludge existing in the first zone, the internal space of the body being divided into a first zone on the upstream side and a second zone on the downstream side relative to the moving direction of the sludge; And a second saucer for receiving moisture separated from the sludge present in the second zone. Specifically, Patent Literature 1 discloses the following technical idea.
The separated water in the first tray (water separated from the sludge in the first zone) is returned to the wastewater tank 50, mixed with untreated wastewater, and then treated again with the water treatment device 51, and the second The separated water in the tray portion is fed into the sludge tank 54. Then, the separated water is mixed with sludge obtained by water treatment in the sludge tank 54, sent again to the flocking device 55, and flocked again by the flocking device 55. This is again solidified by the solid-liquid separation device 57. Liquid separation. At that time, since the solid content concentration of the filtrate sent from the second tray 37 to the sludge tank 54 is high and the amount thereof is very small, the sludge sent from the sludge tank 54 is flocked in the flocking device 55, And the processing efficiency when carrying out the solid-liquid separation process with the solid-liquid separator 57 can be improved. (See paragraphs [0039] to [0041] of Patent Document 1)

The present inventors examined the sludge return system disclosed in Japanese Patent Application Laid-Open No. 9-220598 (Patent Document 1) by conducting a preliminary experiment with an actual organic wastewater treatment sludge. It has become clear that there are several problems.
The preliminary experiment was performed according to the flow shown in FIG. As shown in FIG. 10, surplus sludge from the human waste treatment plant is supplied from a sludge storage tank 101 to a mixing tank 103 in which a polymer flocculant is mixed by a sludge supply pump 102, and a concentrator (corresponding to the first stage) 104. After concentrating with the above, it was dehydrated with a screw press (corresponding to the second stage) 105, and a dehydrated cake having a water content of 80% was discharged. In the screw press 105, 10% of the supplied sludge amount was discharged as separated water of the dehydrator.
The amount of sludge supplied from the sludge storage tank 101 is 600 L / h, the sludge concentration (Cwt%) of the sludge storage tank is set in six stages of 0.7 to 3.5 wt%, and the amount of separated water ( Q1 L / h), amount of separated water of dehydrator 105 (Q2 L / h), separated water sludge concentration of concentrator 104 (C1 wt%), separated water sludge concentration of dehydrator (screw press) 105 (C2 wt%) Asked. Preliminary experiments were performed in two experiments, when the sludge concentration at the concentrator 104 was 7 wt% (preliminary experiment 1) and 5 wt% (preliminary experiment 2).
The case where the sludge arrival concentration is set to 7 wt% is shown in Table 1 as a result of the preliminary experiment 1, and the case where the sludge arrival concentration is set to 5 wt% is shown in Table 2 as the result of the preliminary experiment 2. In both experiments, C1 was less than 0.01 wt%.

The results of Preliminary Experiment 1 are shown in Table 1.

Looking at the relationship between the sludge concentration C1 in the sludge storage tank, the separation water amount Q1 of the concentrator, and the separation water amount Q2 of the dehydrator, it became clear that the trends in the water amounts of Q1 and Q2 differ depending on the sludge concentration.
When the sludge concentration is low: At 0.7 wt% to 1.0 wt%, the separation water amount Q1 of the concentrator is 514 to 540 L / h, whereas the separation water amount Q2 of the dehydrator is 35 to 50 L / h, Most of the separated water is discharged from the concentrator. Q2 is 6.5 to 8.8% of the total amount of separated water (Q1 + Q2) at this time.
On the other hand, when the sludge concentration is high, when the sludge concentration is 2.0 wt% to 3.5 wt%, the separation water amount Q1 of the concentrator is 300 to 429 L / h, whereas the separation water amount Q2 of the dehydrator is 99 to 174 L / h, the amount of separated water from the concentrator decreases, and a large amount of separated water is discharged from the dehydrator. Q2 is 18.8 to 36.7% with respect to the total amount (Q1 + Q2) of the separated water at this time.
That is, when the sludge concentration in the sludge storage tank increases and the amount of solids supplied to the dewatering process increases, not only does the amount of dewatered separation water amount Q2 increase, but the ratio also increases, and the sludge storage tank concentration is It becomes lower than the initial 2.0 wt% to 3.5 wt%. When the sludge from the water treatment system temporarily decreases in the sludge storage tank, the sludge concentration in the sludge storage tank ultimately becomes the sludge concentration of the dewatered separation water.

Table 2 shows the results of Preliminary Experiment 2 in which the concentration reached by the concentrator was 5 wt%.

When the concentration of the sludge storage tank is 2% and 1%, the comparison with the preliminary experiment 1 is performed.
In preliminary experiment 1, at a concentration of 2 wt%, Q1 is 429 L / h, Q2 is 99 L / h, and the ratio of the amount of separated water is 18.8%. On the other hand, in the preliminary experiment 2, at a concentration of 2 wt%, Q1 is 360 L / h, Q2 is 168 L / h, and the ratio of the amount of separated water is 31.8%. From this, when the sludge arrival concentration in the concentrator decreases, the separation water amount Q1 on the concentrator side decreases, but the separation water amount Q2 on the dehydrator side increases, and the ratio of the separation water amount also increases.
Further, when attention is paid to the sludge concentration C2 in the separated water from the dehydrator, C2 is 1.21 wt% when the concentration at the concentrator is 7 wt%, whereas the concentration at the concentrator is 5 wt%. Then, C2 decreases to 0.71 wt%.
As described above, when the separated water from the dehydrator is returned to the sludge storage tank having a concentration of 2 wt%, the sludge concentration C of the sludge storage tank is lower than the concentration of 2 wt%. The actual concentration of the sludge storage tank varies from 2 wt% to C2 in the absence of return, specifically, C2 varies between 0.71 wt% and 1.21 wt%, and the original 2 wt% is not maintained. It will be.

From the above results, four problems of the sludge return system disclosed in JP-A-9-220598 (Patent Document 1) are listed.
(1) Problem 1: If the dehydrated separation liquid is returned to the sludge storage tank, the sludge concentration in the sludge storage tank will decrease, and the sludge amount that has been designed cannot be processed.
The reason for this will be described below.
1) When the sludge concentration in the sludge storage tank decreases, the sludge supply amount to the dehydrator is constant at 600 L / h, so the planned sludge amount (600 L / h × 2 wt% = 12 kg / h) cannot be treated. Become.
When the sludge concentration in the sludge storage tank is 0.71 wt% with the inflow of dehydrated separation liquid (Case 1);
The amount (W) to be processed is 600 L / h × 0.71 wt% = 4.26 kg / h,
When the sludge concentration in the sludge storage tank is 1.21 wt% with the inflow of dehydrated separation liquid (Case 2);
The amount (W) to be processed is 600 L / h × 1.21 wt% = 7.26 kg / h,
That is, with respect to the initial planned sludge amount, it is 36% in case 1 and 60% in case 2, resulting in a situation where the planned throughput cannot be obtained.
2) When the steady state is reached, the sludge concentration from the water treatment system usually flows into the sludge storage tank at 1 to 3.5 wt%. Arranging the amount of treatment for each sludge concentration results in the following. Even if an attempt is made to secure the amount of treatment by keeping the sludge concentration high, the amount of treatment cannot be secured.
If the moisture content of the screw press is 80%, the sludge treatment system in the conventional example is concentrated to a constant concentration by a concentrator regardless of the sludge concentration in the sludge storage tank, and the concentrated sludge is introduced into the screw press. In the case of being concentrated to 7 wt% by a concentrator, the sludge concentration in the dewatered separation liquid of the screw press is constant at 1.2 wt%. When this dewatered separation liquid is returned to the sludge storage tank, even if the water treatment sludge introduced into the sludge storage tank has a high concentration of 3.5 wt%, the returned dewatered separation liquid (sludge concentration) In the steady state of dewatering at a constant supply rate of 600 L / h, the supplied sludge concentration is 1.2 wt. %. From this, when the supply amount is constant at 600 L / h, the planned processing amount depends only on the sludge concentration.
The amount of sludge that can be treated in a steady state and the ratio when there is no return are expressed by the following equation.
Ratio of amount of sludge that can be treated to the case where there is no return (%) = (1.2 wt% / concentration of sludge supplied from water treatment system (wt%)) × 100 (2)
When the sludge concentration supplied from the water treatment system is 1.2 wt%, the concentration of the returned sludge is also constant, so the amount of treated sludge is 100% and does not change.
However, when the concentration of sludge supplied from the water treatment system is 1.5 wt%, the ratio (%) of the amount of sludge that can be treated with respect to the case where there is no return is (1.2 wt% / 1.5 wt%) × 100 = 80 60% when there is no return when the sludge concentration supplied from the water treatment system is 2 wt%, 43% when there is no return when the sludge concentration is 2.8 wt%, and when there is no return when the sludge concentration is 3.5 wt% The processing amount is 34%.

(2) Problem 2: Since the fluctuation range of the sludge concentration is large, the chemical injection rate fluctuates and stable operation of the entire dehydration process becomes impossible.
As shown in Tables 1 and 2, as the sludge concentration in the sludge storage tank increases, the ratio [Q2 / (Q1 + Q2)] of Q2 to the total amount of separated water (Q1 + Q2) increases. That is, the sludge concentration when the dehydrated separation liquid is returned varies greatly as described above. This variation in sludge concentration results in a large change in the chemical injection rate when operating with a constant chemical injection rate in the mixing tank. Stable operation of the entire process becomes impossible.

(3) Problem 3: Injection of chemicals such as polymer flocculant is performed in proportion to the sludge load of organic sludge supplied from the sludge storage tank to the dewatering equipment, and the control is based on the supply of organic sludge. A flow meter is provided in the line, and the injection volume is determined in proportion to the flow rate. In order to return the dehydrated separation liquid to the sludge storage tank, the sludge supplied to the sludge storage tank contains return sludge, and the chemical injection amount is determined for the supply amount including the return sludge volume. Therefore, chemicals are injected again into the returned sludge, and the chemical injection rate per raw sludge increases.

(4) Problem 4: The sludge in the dehydrated separation liquid was initially highly cohesive, but when it is returned to the sludge storage tank, it is diluted with a large amount of sludge in the tank. Is almost gone. Therefore, in dehydrating the sludge in the returned dehydrated separation liquid, it is necessary to inject chemicals again.
In the preliminary experiment, 10% of the total amount of sludge derived from the dehydrated separation liquid was returned to the sludge storage tank. Depending on the operating conditions, up to about 20% of sludge may be returned. The sludge in the separated liquid returned to the sludge storage tank is mixed with the sludge of the water treatment system in the storage tank by air stirring or mechanical stirring in order to make the sludge concentration uniform. Due to this mixing, the sludge having a considerable cohesive force in the state of the separated liquid almost has no cohesive force, and in the flocking device, it is necessary to inject again the same amount of the polymer coagulant as the new sludge. If the amount of sludge to be returned is 20%, the chemical injection rate is increased by 20% for sludge in the water treatment system.
JP-A-9-220598

The present invention was made to solve the above-mentioned problems, and the sludge of the water treatment system is not subject to concentration fluctuations in the sludge storage tank, and the sludge treatment performance of the planned throughput can be maintained. Stable concentration and dehydration treatment is possible at a constant chemical injection rate, and it is only necessary to inject chemicals that substantially treat only the sludge supplied from the water treatment system. An object of the present invention is to provide a method and apparatus for dewatering organic sludge that does not require chemical injection.
More specifically, the present invention improves the sludge recovery rate and lowers the moisture content of the dehydrated cake when a screw press is used as a dehydrator, and performs stable treatment of the entire wastewater treatment facility having a dehydration facility. An object of the present invention is to provide a method and apparatus for dewatering organic sludge.

  In order to achieve the above-mentioned object, the first aspect of the present invention is to add a polymer flocculant or a polymer flocculant and a fibrous dehydration aid to organic wastewater or organic sludge containing suspended solids. Mixing step, concentrating sludge produced in the mixing step to obtain a separation liquid and concentrated sludge, and dehydrating the concentrated sludge obtained in the concentration step with a screw press to dehydrate the cake. And a dehydration step for obtaining a separation liquid, and returning the dehydration separation liquid obtained in the dehydration step to the mixing step and / or the concentration step.

According to the present invention, a concentration step using a multiple disk type concentrator, a screen type gravity concentrator, a belt type concentrator, etc. is provided in the preceding stage of the dehydration step using a screw press, and sludge is removed in this concentration step. It concentrates to 4-10 wt%, and supplies to a dehydration process. In the concentration step, since the concentration of gravity is such that moisture is eliminated by the weight of the sludge flocs, a very small amount of separated liquid with a sludge concentration of 0.01% or less is discharged. From the dehydration step using the screw press, the dehydrated separation liquid in which the dehydrated cake and solid content due to sludge leakage from the screw press are mixed is discharged. This dehydrated separation liquid is returned to the mixing step and / or the concentration step.
The sludge in the dehydrated separation liquid of the screw press is tempered with an inorganic flocculant and a polymer flocculant, and when this is returned to the sludge storage tank as before, the tempering effect disappears. In the invention, by returning the dehydrated separation liquid to the mixing step and / or the concentration step, the sludge in the dehydrated separation liquid can be added to the concentrator or screw press without injecting the inorganic flocculant or polymer flocculant again. It was experimentally verified that dehydration was possible.
The present invention has the following effects.
(1) Since the sludge of the water treatment system does not undergo concentration fluctuations in the sludge storage tank, the sludge treatment performance of the planned throughput can be maintained.
(2) Since the concentration of water treatment sludge does not change in the sludge storage tank, stable concentration and dehydration treatment can be performed at a constant chemical injection rate.
(3) The sludge supplied from the sludge storage tank and the dehydrated separation liquid are mixed in the mixing step or the concentration step. Since the sludge from the dehydrated separation liquid has already been tempered with chemicals, it is possible to substantially treat only the sludge supplied from the water treatment system. No chemical injection is required.
Human waste, septic tank sludge and the like contain suspended matter having a sludge concentration of 5000 to 20000 mg / L. The present invention is also applied to the treatment of suspended matter from such organic wastewater.

According to the present invention, by adding a polymer flocculant or a polymer flocculant and a fibrous dehydration aid to the mixing step, the dewatering efficiency of the entire system is further improved. The reason is described below.
In general, the particle diameter of raw sludge generated by biological treatment is composed of fine particles of 0.5 to 200 μm. The addition of fibrous dehydration aids reduces the moisture content of the dehydrated cake by adding a fibrous dehydration aid and polymer flocculant having a fiber diameter of 5-30 μm and a fiber length of 3-30 mm to this raw sludge. Thus, the fiber component is entangled with the raw sludge, and most of the sludge becomes a sludge mass of 3 to 8 mm. This makes it difficult for the sludge mass to be destroyed in the concentration / dehydration step. In particular, in the screw press, the sludge mass is less destroyed at the place where the pressure in the latter half of the pressing / dehydrating zone is applied, and the moisture content of the dewatered cake is reduced accordingly.

  The second aspect of the present invention includes a dehydrating aid mixing step of adding and mixing an inorganic flocculant and / or a fibrous dehydrating aid to organic wastewater or organic sludge containing suspended solids, and the dehydrating aid. A mixing step in which a polymer flocculant is added to and mixed with organic wastewater or organic sludge discharged from the mixing step, and a concentration step in which the aggregated sludge generated in the mixing step is concentrated to obtain a separated liquid and concentrated sludge. And a dehydration step of dehydrating the concentrated sludge obtained in the concentration step with a screw press to obtain a dehydrated cake and a dehydrated separation liquid, and mixing the dehydration separation liquid obtained in the dehydration step with the dehydration aid An organic sludge dewatering method comprising returning to the step and / or the mixing step and / or the concentration step.

  In the second aspect of the present invention, a dehydration aid mixing step of adding an inorganic flocculant and / or a fibrous dehydration aid is provided before the mixing step. As the inorganic flocculant, ferric chloride, polyferric sulfate (polyiron), slaked lime, and aluminum-based flocculants mainly containing iron are used. By injecting the inorganic flocculant, the floc strength of the pre-concentration sludge is increased, and the separation liquid is easily discharged in the concentration step and the dehydration step.

  In the second aspect of the present invention, a fibrous dehydration aid is added in the dehydration aid mixing step. The fibrous dehydrating auxiliary agent is composed of components such as polyethylene terephthalate, cellulose, nylon, and rayon, and those having a fiber diameter of 5 to 30 μm and a fiber length of 3 to 30 mm are used. When this fibrous dehydration aid is added to the raw sludge, the moisture content of the dehydrated cake in the screw press is reduced by about 5 to 10 points as compared with the case where it is not added. The addition rate of the fibrous dehydration aid is 3 to 10% by weight and usually 4 to 8% per solid sludge (Dry Solid; DS). When the addition rate is less than 3%, the decrease in the moisture content of the dehydrated cake is less than 5 points, and the effect of addition is low. When the addition rate exceeds 10%, the water content of the dehydrated cake is not much different from that when the addition rate exceeds 10%, and when the addition rate exceeds 10%, excessive addition occurs.

In general, the particle diameter of raw sludge generated by biological treatment is composed of fine particles of 0.5 to 200 μm. The fiber dehydration aid having a fiber diameter of 5 to 30 μm and a fiber length of 3 to 30 mm and a polymer flocculant are added to the raw sludge, and the moisture content of the dehydrated cake is reduced. By addition, the fiber component is entangled with the raw sludge, and most of the sludge becomes a sludge mass of 3 to 8 mm. This makes it difficult for the sludge mass to be destroyed in the concentration / dehydration step. In particular, in the screw press, the sludge mass is less destroyed at the place where the pressure in the latter half of the pressing / dehydrating zone is applied, and the moisture content of the dewatered cake is reduced accordingly.
As described in the first aspect of the present invention, the addition of the fibrous dehydrating auxiliary agent is also possible in a mixing tank in which a polymer flocculant is injected and mixed. However, when the fibrous dehydrating auxiliary agent is added in the dehydrating auxiliary agent mixing step, the fiber and sludge are sufficiently mixed.

  The third aspect of the present invention is characterized in that the dehydrated separation liquid is subjected to solid-liquid separation, and the obtained sludge side is returned to the dehydration aid mixing step and / or the mixing step and / or the concentration step. This is a method of dewatering organic sludge. The filtrate side obtained by the solid-liquid separation is discharged out of the system together with the dehydrated separation liquid discharged from the screw press.

In the present invention, at 2 wt% sludge concentration of raw sludge, when the sludge quantity 10 m 3 ^/ day, dewatering the separated liquid to the dehydration step dehydration separated liquid is generated in the 3m 3 ^/ day, there is leakage of sludge The solids concentration of is 0.5 to 0.7 wt%. The dehydrated separation liquid containing the solid matter can be concentrated to about 1.5% again by solid-liquid separation. That is, the amount of sludge mixed liquid returned to any one of the dehydrating auxiliary agent mixing step, the mixing step and the concentration step is 3 m ³ / day when solid-liquid separation is not performed. In the case of separation, it becomes 1 to 1.5 m ³ / day, the amount of liquid to be returned becomes 1/3 to 1/2, and the tank capacity of the process of returning the mixing tank or mixing tank can be extremely small.

According to a fourth aspect of the present invention, there is provided a mixing tank in which a polymer flocculant or a polymer flocculant and a fibrous dehydrating auxiliary agent are added to and mixed with organic waste water or organic sludge containing suspended solids, and the mixing tank A concentrator for concentrating the coagulated sludge produced in step 1 to obtain a separated liquid and concentrated sludge, a screw press for dehydrating the concentrated sludge obtained in the concentrator to obtain a dehydrated cake and a dehydrated separated liquid, and the screw An organic sludge dewatering apparatus comprising: a dewatering separation liquid obtained by pressing, and a return conduit for returning the dewatered separation liquid to the mixing tank and / or the concentrator.
A fourth aspect of the present invention is a dehydration apparatus corresponding to the dehydration method of the first aspect of the present invention.

According to a fifth aspect of the present invention, an organic flocculant and / or organic sludge containing suspended solids is mixed with an inorganic flocculant and / or a fibrous dehydrating auxiliary agent, and discharged from the mixing tank. A mixing tank in which a polymer flocculant is added to and mixed with organic wastewater or organic sludge; a concentrator for concentrating the coagulated sludge generated in the mixing tank to obtain a separated liquid and concentrated sludge; and the concentrator A screw press that obtains a dehydrated cake and a dehydrated separated liquid by dehydrating the obtained concentrated sludge, and the dehydrated separated liquid obtained by the screw press to the mixing tank and / or the mixing tank and / or the concentrator An organic sludge dewatering device comprising a return conduit for returning.
The fifth aspect of the present invention is a dehydrating apparatus corresponding to the dehydrating method of the second aspect of the present invention.

According to a sixth aspect of the present invention, there is provided a solid-liquid separation device for solid-liquid separation of the dehydrated separation liquid, and the sludge side obtained by the solid-liquid separation device is connected to the mixing tank and / or the mixing device by the return pipe. An organic sludge dewatering device which is returned to a tank and / or the concentrator.
The sixth aspect of the present invention is a dehydrating apparatus corresponding to the dehydrating method of the third aspect of the present invention.

A seventh aspect of the present invention is an organic sludge dewatering apparatus characterized in that the means for adding the fibrous dehydrating auxiliary agent is provided in the mixing tank and / or the mixing tank.
An eighth aspect of the present invention is an organic sludge dewatering device, characterized in that the means for adding the fibrous dewatering auxiliary agent is provided in the sludge storage tank installed in the preceding stage of the mixing tank or the preceding stage of the mixing tank. is there. In this embodiment, before the inorganic flocculant or the polymer flocculant is injected, the fibrous dehydrating auxiliary agent is injected into the sludge storage tank.

A ninth aspect of the present invention includes a cylindrical outer cylinder, a screw shaft disposed concentrically with the outer cylinder inside the outer cylinder, and a screw blade fixed to the screw shaft, A first half portion having a screen having a plurality of apertures for discharging the dehydrated separation liquid, a supply port for organic waste water or organic sludge containing suspended matters, and an outlet portion for the dehydrated cake The opening in the portion having a length equal to the inner diameter of the outer cylinder from at least the end on the supply port side has an opening area of 1.8 to 12.6 mm. ² is a screw press for dewatering organic sludge characterized by having a diameter of about 1.5 mm to about 4.0 mm in terms of a perfect circle.
In a preferred aspect of the present invention, the opening of the outer cylinder screen in the first half near the supply port has an opening area of 3.1 to 7.1 mm ² , and the diameter of the opening is approximately equal to a perfect circle. 2.0 mm to about 3.0 mm.

The screw press in the ninth aspect of the present invention allows sludge to leak from at least the vicinity of the sludge supply port. In particular, it is based on the knowledge that the water content of the dewatered cake decreases when the solid (non-dehydrated sludge) is contained in the separated liquid from the portion corresponding to the concentrated portion of the outer cylinder of the screw press. Specifically, the opening of the outer cylinder is closed and reduced by solids (non-dehydrated sludge), and therefore, the sludge separation liquid near the screw shaft that is separated from the outer cylinder is difficult to be discharged from the opening. In order to prevent the clogging of the apertures and the reduction of the apertures due to solid matter (non-dehydrated sludge), it is important to increase the aperture area, that is, to enlarge the diameter of the aperture in terms of a perfect circle.
In the present invention, the opening area of the opening of the outer cylinder screen of the screw press is 1.8 to 12.6 mm ² , and the diameter when the area is a perfect circle is about 1.5 mm to about 4.0 mm. In the conventional screw press, the diameter or area of the opening is reduced, and the sludge is dehydrated as much as possible in the separated liquid, and the screw press of the present invention is used. The technical idea is completely different from a conventional screw press. By using the screw press of the present invention, it is possible to reduce the water content of the dehydrated cake by 10 to 20 points. Such an effect is exhibited when the raw sludge has a higher fiber content and the sludge has a larger particle size. Further, the aperture ratio (ratio of the aperture area to the outer cylinder surface area) is 50% when the aperture diameter (diameter of the aperture) is 1.5 mm, and the aperture ratio decreases as the aperture diameter increases. It is 34% at 4 mm. In the present invention, the diameter of the opening is referred to as the opening diameter.

  The tenth aspect of the present invention reinforces the characteristics of the ninth aspect of the present invention, and is provided with a multiple disk type concentrator having a slit width of 0.5 mm to 1.5 mm in the preceding stage of the screw press. This is an organic sludge dewatering device.

In the present invention, the following three points contribute mainly to the fact that a dehydrated cake having a low water content is obtained and the sludge recovery rate is increased.
As a first point: the separation liquid flowing out of the system from the dehydration equipment is concentrated only from the concentration step (concentrator), and this separation liquid has an extremely low sludge concentration of 0.01 wt% or less. As a result, it flows out of the system and the sludge load on the water treatment facility mainly composed of biological treatment is reduced. The amount of the separated liquid is 50 to 70% with respect to the amount of sludge flowing into the concentration step (concentrator), and is responsible for most of the separated liquid amount of the dehydration equipment. The sludge recovery rate as a dehydration facility comprising a concentrator and a screw press can be maintained at an extremely high level of 95% or more, and an efficient dehydration facility can be achieved.

  As a second point: By concentrating the separation liquid only from the concentration step (concentrator), it becomes unnecessary to consider the sludge recovery rate of the separation liquid from the screw press. Therefore, the moisture content of the dewatered cake can be reduced by increasing the aperture diameter of the aperture which is the separation liquid permeation portion in the cylindrical outer cylinder screen of the screw press and intentionally leaking sludge. Thereby, the cake moisture content can be reduced without deteriorating the sludge recovery rate of the dewatering equipment.

  Third point: In the cylindrical outer cylinder screen of the screw press, the sludge permeated through the opening is increased in the aggregated state by mixing the polymer flocculant by increasing the area per opening of the separation liquid permeation part. It is returned with keeping Therefore, for the sludge returned from the screw press, it is not necessary to add the polymer flocculant in the mixing tank or the concentrator, so that the injection amount for the raw sludge is sufficient, and the polymer flocculant is not wasted. Similarly, the inorganic flocculant and the fibrous dehydrating auxiliary agent injected in the mixing tank do not need to be added to the sludge returned from the screw press.

The present invention has the following effects.
(1) Since the sludge of the water treatment system does not undergo concentration fluctuations in the sludge storage tank, the sludge treatment performance of the planned throughput can be maintained.
(2) Since the concentration of water treatment sludge does not change in the sludge storage tank, stable concentration and dehydration treatment can be performed at a constant chemical injection rate.
(3) Since the sludge in the dehydrated separation liquid discharged from the dehydration step (screw press) has already been conditioned with chemicals, it is possible to substantially treat only the sludge supplied from the water treatment system. No new chemical injection is required for sludge in the dehydrated separation liquid.
(4) By collecting the separated liquid flowing out of the dehydration facility only from the concentration process (concentrator) with a good sludge recovery rate, sludge recovery of the dehydrated separation liquid separated by the screw press is performed. It is not necessary to consider the rate, and the aperture diameter of the screen can be increased in the cylindrical outer cylinder of the screw press.
(5) The cake moisture content can be reduced by increasing the aperture diameter of the aperture in the cylindrical outer cylinder of the screw press.
(6) By making the diameter of the opening large in the cylindrical outer cylinder of the screw press, even when a fibrous dehydration aid is used, the opening is not blocked, and it has been difficult to reduce the water content so far. It is possible to achieve a low water content with respect to the sludge and the like.
(7) By unifying the separation liquid flowing out of the system from the dehydration facility only from the concentrator, the sludge recovery rate at the dehydration facility is improved, the inflow of sludge into the water treatment is reduced, and the water treatment The adverse effect on is eliminated.

The organic sludge dewatering method and apparatus according to the present invention will be described below with reference to FIGS. In FIG. 1 to FIG. 9, the same or corresponding components will be described with the same reference numerals.
FIG. 1 is a schematic view showing a first embodiment of an organic sludge dewatering apparatus according to the present invention. As shown in FIG. 1, the organic sludge dewatering apparatus comprises a mixing tank 2 in which a polymer flocculant and a fibrous dewatering auxiliary are added to and mixed with organic sludge, and agglomerated sludge generated in the mixing tank 2. Concentrated to obtain a separated liquid and concentrated sludge by concentration treatment, a screw press 4 to obtain a dehydrated cake and a dehydrated separated liquid by pressing and dewatering the obtained concentrated sludge, and obtained by pressing and dewatering with the screw press 4. A return line (return line) having a dehydration / separation liquid receiving tank 5 for storing the dehydrated separation liquid and a return pump 6 for returning the dehydration / separation liquid in the dehydration / separation liquid receiving tank 5 to the mixing tank 2 and / or the concentrator 3. ) RL. Reference numeral 7 denotes a fibrous dehydrating auxiliary agent supply device. The fibrous dehydrating auxiliary agent supply device is an apparatus that can quantitatively transfer the fibrous dehydrating auxiliary agent to the mixing tank 2.

As shown in FIG. 1, the organic sludge discharged in the organic wastewater treatment process in the water treatment facility 50 is stored in a sludge storage tank 51 and then mixed through a supply line 53 having a sludge supply pump 52. Sent to tank 2. In the mixing tank 2, flocs are generated by mixing organic sludge with a polymer flocculant or a polymer flocculant and a fibrous dehydration aid.
As the polymer flocculant charged into the mixing tank 2, a cationic or amphoteric polymer flocculant is usually used. The method for injecting the polymer flocculant is to measure the sludge concentration of organic sludge in advance, and provide a flow meter 54 in the organic sludge supply line 53 so that the target injection amount is obtained with respect to the measured flow rate. Proportionally injected. The fibrous dehydration aid is a fibrous dehydration aid having a fiber diameter of 5 to 30 μm and a fiber length of 3 to 30 mm. By mixing this fibrous dewatering aid together with the polymer flocculant into the raw sludge, the fiber component is entangled with the raw sludge in the presence of the polymer flocculant, and most of the raw sludge becomes a sludge mass of 5 to 20 mm. This makes it difficult for the sludge mass to be destroyed in the concentration / dehydration step. In particular, in the screw press, the destruction of the sludge mass where the pressure in the latter half of the pressing / dehydrating zone is applied is reduced, and the moisture content of the dewatered cake is also reduced accordingly.

  The size of the floc generated in the mixing tank 2 is, for example, 5 to 20 mm in diameter, and the sludge concentration of the floc sludge is 1 to 3 wt%. The sludge thus flocked is introduced into the concentrator 3 where it is concentrated. The concentrator 3 gravity-concentrates the floc sludge and separates it into a sludge having a high sludge concentration and a separated liquid, such as a multi-disc type concentrator, a screen type gravity concentrator, a belt type concentrator, etc. There is. In the multi-disk concentrator, the slit width of the filtration surface is 0.5 mm to 1.5 mm. If the slit width is smaller than 0.5 mm, the concentration of sludge becomes insufficient due to insufficient discharge of the separation liquid. If the slit width exceeds 1.5 mm, the sludge leaks from the concentrator. Since the sludge recovery rate of the entire dehydration facility is greatly reduced, rational dehydration treatment cannot be performed. In the belt type concentrator, the sludge conditioned with the polymer flocculant on the belt is gravity concentrated while moving the belt.

The sludge concentration of the sludge concentrated in the concentrator 3 is 4 to 10 wt%, particularly about 6 to 8 wt%, and the sludge concentration of the separation liquid is 0.01 wt% or less. Further, the amount of the separation liquid is 70 to 80 wt% with respect to the amount of sludge flowing into the concentrator 3, but the sludge recovery rate is 95% or more.
The sludge concentrated by the concentrator 3 is put into the screw press 4 and dehydrated by the screw press 4.

As shown in FIG. 1, in the present invention, since the concentrator 3 is installed in front of the screw press 4, the dehydrated separation liquid is discharged in the concentration zone of the screw press 4. Even if a product (non-dehydrated sludge) is contained, it is possible to provide a sludge dewatering method and apparatus having a high recovery rate and an extremely low moisture content.
In particular, when there is a solid (non-dehydrated sludge) in the separated liquid from the opening of the outer cylinder in the concentrated portion of the screw press 4, the moisture content of the dehydrated cake decreases. When the opening of the outer cylinder of the screw press 4 is closed with solids (non-dehydrated sludge) and the area of the opening is reduced, the sludge separation water near the screw shaft separated from the outer cylinder becomes difficult to be discharged from the opening. . In order to prevent the clogging of the apertures and the reduction of the apertures due to solid matter (non-dehydrated sludge), increase the aperture area, that is, increase the size of the aperture, specifically, the perfect circle of the aperture It is important to increase the equivalent diameter.

The screw press 4 includes a screw shaft and a screw blade concentric with the cylindrical outer cylinder inside the cylindrical outer cylinder. The cylindrical outer cylinder includes a plurality of openings for discharging a separated liquid. The outer cylinder is composed of a first half portion in the vicinity of the sludge supply port and a second half portion connected to the first half portion. Assuming that the diameter of the cylindrical outer cylinder is D, the opening is converted into a perfect circle at least from the end near the supply port of sludge to 1D to 2D, and the diameter is 1.5 mm to 4 mm (open). It is 7-50 mm < ² > as a hole area, More preferably, it is ² mm-3 mm in diameter (12.6-28 mm < ² > as a hole area). In this screw press, since the strength of the outer cylinder is also necessary, the aperture ratio is required to be 15 to 50%. The hole area ratio is defined by the following equation.
Opening ratio (%) = (opening area (m ² ) / surface area of outer cylinder (m ² )) × 100 (3)

In the present invention, the opening of the screen in the cylindrical outer cylinder of the screw press 4 is, for example, a perfect circle and has a diameter of 2 to 3 mm. Therefore, the sludge leaked from the opening has a diameter of 2 It becomes a flock shape with a size of ˜3 mm. Therefore, since the returned sludge has a slit width of the filtration surface of the concentrator 3 of about 1 mm, it is separated from the water by the concentrator 3 and the sludge is recovered.
From the series of flows, the separation liquid discharged out of the dehydration equipment system is only the separation liquid separated by the concentrator 3, and the sludge recovery rate as a whole dehydration equipment is 95% or more.
The concentrated sludge thrown into the space between the cylindrical outer cylinder and the screw shaft advances to the sludge outlet side as the screw shaft rotates. Since the space between the opening of the cylindrical outer cylinder and the screw shaft gradually becomes narrower in the direction in which the sludge proceeds, the concentrated sludge is compressed. As the concentrated sludge is compressed, the concentrated sludge is separated into a dehydrated cake having a lower moisture content and a separation liquid containing the sludge leaked from the opening of the outer cylinder.

The dewatered cake is discharged from the sludge discharge portion of the screw press 4 to the outside of the machine. The dehydrated separation liquid is discharged out of the machine through the opening of the cylindrical outer cylinder. The moisture content of the dewatered cake discharged here is, for example, 65 to 80 wt%, and the sludge concentration of the dehydrated separation liquid containing the leaked sludge is 1 to 2 wt%. The sludge recovery rate is about 80 to 90% with respect to the amount of sludge thrown into the screw press 4.
The dehydrated cake is discharged out of the dehydration system. The dehydrated separation liquid from the screw press 4 is returned to the mixing tank 2 or the concentrator 3 through a return line (return line) RL. As a result, the sludge contained in the dehydrated separation liquid leaks from the opening of the outer cylinder of the screw press 4, and the entire amount of sludge is returned to the dehydration equipment system.
FIG. 1 shows an example in which the dehydrated separation liquid is returned to the mixing tank 2 or the concentrator 3 via the dehydrated liquid receiving tank 5, but the dehydrating liquid receiving tank is omitted and the screw press 4 is omitted. May be directly returned to the mixing tank 2 or the concentrator 3.

FIG. 2 is a schematic view showing a second embodiment of the organic sludge dewatering apparatus according to the present invention. As shown in FIG. 2, the organic sludge dewatering apparatus includes a mixing tank 1 for adding an inorganic flocculant and / or a fibrous dewatering aid to the organic sludge, and an organic sludge discharged from the mixing tank 1. A mixing tank 2 in which a polymer flocculant is added and mixed, a concentrating machine 3 for concentrating the coagulated sludge generated in the mixing tank 2 to obtain a separated liquid and concentrated sludge, and a compression dehydrating process for the obtained concentrated sludge The screw press 4 for obtaining the dehydrated cake and the dehydrated separation liquid, the dehydrated separation liquid receiving tank 5 for storing the dehydrated separation liquid obtained by the press dehydration treatment by the screw press 4, and the dehydrated separated liquid in the dehydrated liquid separating tank 5 And a return line (return line) RL having a return pump 6 for returning the mixture to the mixing tank 1 and / or the mixing tank 2 and / or the concentrator 3. Reference numeral 7 denotes a fibrous dehydrating auxiliary agent supply device. The fibrous dehydrating auxiliary agent supply apparatus is an apparatus that can quantitatively transfer the fibrous dehydrating auxiliary agent to the mixing tank 1.
In FIG. 2, the water treatment facility 50 and the sludge storage tank 51 are not shown.

The organic wastewater sludge discharged in the organic wastewater treatment process in the water treatment facility is mixed with the inorganic flocculant in the mixing tank 1 and agglomerated, and a large number of fine agglomerated flocs are formed in the sludge.
As the inorganic flocculant, ferric chloride, polyferric sulfate (polyiron), slaked lime, and aluminum-based flocculants mainly containing iron are used. In addition to the inorganic flocculant, a fibrous dehydrating aid may be added to the mixing tank 1. The fibrous dehydrating auxiliary agent is composed of components such as polyethylene terephthalate, cellulose, nylon, and rayon, and has a fiber diameter of 5 to 30 μm and a fiber length of 3 to 30 mm.

The sludge coagulated in the mixing tank 1 is mixed with the polymer flocculant in the mixing tank 2, and fine flocculent flocs are combined with the polymer flocculant to generate larger flocs. The sludge thus flocked is introduced into the concentrator 3 where it is concentrated. The flow after the concentrator is the same as that in the first embodiment, but in the second embodiment, the dehydrated separation liquid from the screw press 4 is mixed in the mixing tank 1 via the return line (return line) RL. And / or returned to the mixing tank 2 and / or the concentrator 3.
Also in 2nd Embodiment, the sludge collection | recovery rate as the whole dehydration equipment will be 95% or more.

  FIG. 3 is a schematic view showing a third embodiment of the organic sludge dewatering apparatus according to the present invention. As shown in FIG. 3, the organic sludge dewatering apparatus includes a mixing tank 2 in which a polymer flocculant is added to and mixed with organic sludge, and a condensed liquid obtained by concentrating the coagulated sludge generated in the mixing tank 2. And a concentrator 3 that obtains concentrated sludge, a screw press 4 that obtains a dehydrated cake and a dehydrated separated liquid by squeezing and dewatering the obtained concentrated sludge, and a dehydrated separated liquid obtained by squeezing and dewatering using the screw press 4 A dehydrating separation liquid receiving tank 5 to be stored and a return line (returning pipe line) RL having a returning pump 6 for returning the dehydrating separation liquid in the dehydrating separation liquid receiving tank 5 to the mixing tank 2 and / or the concentrator 3 Yes.

As shown in FIG. 3, the organic sludge discharged during the organic wastewater treatment process in the water treatment facility is stored in the sludge storage tank 51. In the present embodiment, the fibrous dewatering auxiliary agent is charged into the sludge storage tank 51 and mixed with the organic sludge in the sludge storage tank 51 in advance. The sludge supplied from the sludge storage tank 51 is mixed with the polymer flocculant in the mixing tank 2 and combined with the polymer flocculant to generate a floc. The sludge thus flocked is introduced into the concentrator 3 where it is concentrated. The flow after the concentrator is the same as that of the first embodiment shown in FIG. 1, and the dehydrated separation liquid from the screw press 4 is supplied to the mixing tank 2 and / or the concentrator via the return line (return line) RL. 3 is returned.
The fibrous dehydration aid to be introduced into the sludge storage tank 51 is made of a component that becomes a fiber such as polyethylene terephthalate, cellulose, nylon, or rayon, and has a fiber diameter of 5 to 30 μm and a fiber length of 3 to 30 mm. .
From the series of flows, the separation liquid discharged out of the dehydration equipment system is only the separation liquid separated by the concentrator 3, and the sludge recovery rate as a whole dehydration equipment is 95% or more.

  FIG. 4 is a schematic view showing a fourth embodiment of the organic sludge dewatering apparatus according to the present invention. As shown in FIG. 4, the organic sludge dewatering apparatus adds a polymer flocculant to the mixing tank 1 for adding an inorganic flocculant to the organic sludge and the organic sludge discharged from the mixing tank 1. A mixing tank 2 for mixing, a concentrator 3 for concentrating the coagulated sludge generated in the mixing tank 2 to obtain a separated liquid and concentrated sludge, and a dehydrated cake and a dehydrated separated liquid by pressing and dewatering the obtained concentrated sludge A mixing press 1 and / or mixing the dehydrating / separating liquid 5 in the dehydrating / separating liquid receiving tank 5. And a return line (return line) RL having a return pump 6 for returning to the tank 2 and / or the concentrator 3.

As shown in FIG. 4, the organic sludge discharged during the organic wastewater treatment process in the water treatment facility is stored in the sludge storage tank 51. In the present embodiment, the fibrous dewatering auxiliary agent is charged into the sludge storage tank 51 and mixed with the organic sludge in the sludge storage tank 51 in advance. The sludge supplied from the sludge storage tank 51 is mixed with the inorganic flocculant in the mixing tank 1 and agglomerated. That is, a large number of fine aggregated flocs containing fibers are formed in the sludge. The sludge coagulated in the mixing tank 1 is mixed with the polymer flocculant in the mixing tank 2, and fine flocculent flocs are combined with the polymer flocculant to generate larger flocs. The sludge thus flocked is introduced into the concentrator 3 where it is concentrated. The flow after the concentrator is the same as that of the second embodiment shown in FIG. 2, and the dehydrated separation liquid from the screw press 4 is mixed into the mixing tank 1 and / or the mixing tank via the return line (return line) RL. 2 and / or returned to the concentrator 3.
From the series of flows, the separation liquid discharged out of the dehydration system is only the separation liquid separated by the concentrator 3, and in this embodiment, the sludge recovery rate of the entire dehydration system is 95% or more. .

  FIG. 5 is a schematic view showing a fifth embodiment of the organic sludge dewatering apparatus according to the present invention. As shown in FIG. 5, the dewatering device for organic sludge is a mixing tank 1 for adding a fibrous dewatering aid to the organic sludge, and a polymer flocculant is added to the organic sludge discharged from the mixing tank 1. A mixing tank 2 for mixing, a concentrator 3 for concentrating the agglomerated sludge generated in the mixing tank 2 to obtain a separated liquid and a concentrated sludge, and pressing and dewatering the obtained concentrated sludge for dewatering cake and dewatering A screw press 4 for obtaining a separated liquid, a dehydrated separated liquid receiving tank 5 for storing a dehydrated separated liquid obtained by a pressure dehydration treatment by the screw press 4, a mixed tank 1 and / or a dehydrated separated liquid in the dehydrated separated liquid receiving tank 5 Alternatively, a return line (return line) RL having a return pump 6 for returning to the mixing tank 2 and / or the concentrator 3 is provided. Reference numeral 7 denotes a fibrous dehydrating auxiliary agent supply device. The fibrous dehydrating auxiliary agent supply apparatus is an apparatus that can quantitatively transfer the fibrous dehydrating auxiliary agent to the mixing tank 1.

  As shown in FIG. 5, the organic sludge discharged | emitted in the organic waste water treatment process in a water treatment facility is introduce | transduced into the mixing tank 1, and is mixed with a fibrous dehydration adjuvant in this mixing tank 1. As shown in FIG. The sludge from the mixing tank 1 is mixed with the polymer flocculant in the mixing tank 2 to generate floc. The sludge thus flocked is introduced into the concentrator 3 where it is concentrated. The flow after the concentrator is the same as that of the second embodiment shown in FIG. 2, and the dehydrated separation liquid from the screw press 4 is mixed into the mixing tank 1 and / or the mixing tank via the return line (return line) RL. 2 and / or returned to the concentrator 3.

  FIG. 6 is a schematic view showing a sixth embodiment of the organic sludge dewatering apparatus according to the present invention. As shown in FIG. 6, the dewatering device for organic sludge is a mixing tank 1 for adding a fibrous dewatering auxiliary to organic sludge, and a polymer flocculant is added to the organic sludge discharged from this mixing tank 1. A mixing tank 2 for mixing, a concentrator 3 for concentrating the agglomerated sludge generated in the mixing tank 2 to obtain a separated liquid and a concentrated sludge, and pressing and dewatering the obtained concentrated sludge for dewatering cake and dewatering A screw press 4 for obtaining a separated liquid, a dehydrated separated liquid settling tank 15 for storing a dehydrated separated liquid obtained by pressing dewatering treatment with the screw press 4 to precipitate and separate concentrated sludge, and a concentration in the dehydrated separated liquid settling tank 15 And a return line (return line) RL having a return pump 6 for returning the concentrated sludge to the mixing tank 1 and / or the mixing tank 2 and / or the concentrator 3. Reference numeral 7 denotes a fibrous dehydrating auxiliary agent supply device. The fibrous dehydrating auxiliary agent supply apparatus is an apparatus that can quantitatively transfer the fibrous dehydrating auxiliary agent to the mixing tank 1.

As shown in FIG. 6, the organic sludge discharged | emitted in the organic waste water treatment process in a water treatment facility is introduce | transduced into the mixing tank 1, and is mixed with an inorganic flocculant and a fibrous dehydration auxiliary agent in this mixing tank 1. . The sludge coagulated in the mixing tank 1 is mixed with the polymer flocculant in the mixing tank 2, and fine flocculent flocs are combined with the polymer flocculant to generate larger flocs. The sludge thus flocked is introduced into the concentrator 3 where it is concentrated. The dehydrated separated liquid from the screw press 4 is introduced into the dehydrated separated liquid settling tank 15, and the concentrated sludge is precipitated and separated in the dehydrated separated liquid settling tank 15. Then, the concentrated sludge concentrated in the dewatered separation liquid precipitation tank 15 is returned to the mixing tank 1 and / or the mixing tank 2 and / or the concentrator 3 via the return line (return pipe line) RL. Further, the separation liquid separated in the dehydration separation liquid precipitation tank 15 is discharged out of the system.
The separation liquid discharged out of the dehydration equipment system from the series of flows is only the separation liquid separated in the concentrator 3 and the dehydration separation liquid precipitation tank 15, and in this embodiment also the sludge recovery as the whole dehydration equipment. The rate is 95% or more.

  FIG. 7 is an external view of a screw press applied to the organic sludge dewatering apparatus of the present invention shown in FIGS. 1 to 6. As shown in FIG. 7, the screw press 4 is fixed to the cylindrical outer cylinder 41, a screw shaft 42 disposed concentrically with the cylindrical outer cylinder 41 inside the cylindrical outer cylinder 41, and the screw shaft 42. Screw blades 43 are provided. The cylindrical outer cylinder 41 includes an outer cylinder screen having a large number of openings 41h for discharging the dehydrated separation liquid, and has an organic waste water or organic sludge supply port 41a containing suspended solids. The first half portion FH and the second half portion RH having a dehydrated cake outlet 41b. For the screw press, if the total length of the outer cylinder is L (mm) and the inner diameter of the outer cylinder is D (mm), the total length of the outer cylinder is set to 4 to 5 times the inner diameter of the outer cylinder, L = 4D to 5D Has been. In the screw press, the dehydrated separation liquid is discharged most from 1D to 2D from the end on the sludge supply port side, and this portion is called a concentration zone. A pressing / dehydrating zone is formed following the concentration zone.

In the screw press 4 shown in FIG. 7, each opening 41 h located at a portion (1D) having a length equal to at least the inner diameter (D) of the outer cylinder from the end on the supply port side has an opening area of 1. 8 to 12.6 mm ² , and the diameter is set to about 1.5 mm to about 4.0 mm in terms of a perfect circle. Preferably, the opening 41h has an opening area of 3.1 to 7.1 mm ² and a diameter of about 2.0 mm to about 3.0 mm in terms of a perfect circle. The cylindrical outer cylinder 41 is formed by a screen (outer cylinder screen). Since this screen applies a force to the inside during dehydration, a punching screen made of a punching metal is suitable for the outer cylinder screen.

  In the screw press 4, the space between the cylindrical outer cylinder 41 and the screw shaft 42 is narrowed from the sludge supply port side toward the dehydrated cake outlet side. In the screw press 4, sludge is supplied from the sludge supply port 41 a between the outer cylinder 41 and the screw shaft 42, the screw shaft 42 is rotated to dehydrate the sludge and the dehydrated cake is dehydrated from the outer cylinder 41. It discharges | emits from the cake exit part 41b. The dehydrated cake outlet portion 41 b of the outer cylinder 41 is connected to the dehydrated cake discharge portion 44, and the dehydrated cake is discharged out of the system from the dehydrated cake outlet 44 a of the dehydrated cake discharge portion 44. Further, the dewatered and separated water is discharged out of the system from the dewatered and separated water outlet 45.

  FIG. 8 is a schematic view showing an example of the cylindrical outer cylinder 41 of the screw press 4. As shown in FIG. 8, punching metal is mainly employed in the screen constituting the cylindrical outer cylinder 41 of the screw press 4. In the present invention, a screen made of a punching metal is referred to as a punching screen. The screen is divided into four in the range of (1) to (4).

FIGS. 9A, 9 </ b> B, and 9 </ b> C are partial enlarged views showing a part of a punching screen 41 p constituting the cylindrical outer cylinder 41 of the screw press 4. In the punching screen 41p shown in FIG. 9A, each opening 41h is a square having a side of 3.0 mm, and the opening area is 9.0 mm ² . The pitch of the holes 41h is 5 mm, and the hole area ratio is 36%.
In the punching screen 41p shown in FIG. 9B, each opening 41h is an oblong hole having a width of 2.0 mm × a length of 10 mm, and the opening area is 19.1 mm ² . The pitch of the openings 41h is 4 mm × 14 mm, and the opening ratio is 34.1%.
In the punching screen 41p shown in FIG. 9C, each opening 41h is a perfect circle having a diameter of 3.0 mm, and the opening area is 7.1 mm ² . The pitch of the holes 41h is 4.5 mm, and the hole area ratio is 40.3%.

（２）結果
従来例では汚泥貯留槽に脱水分離液を返送した影響で、脱水処理量は１１．３（ｋｇ／ｈ）となった。これに対し、本発明では、脱水処理量は１３．３（ｋｇＤＳ／ｈ）で安定し、脱水ケーキの排出能力が１８％向上した。さらに、従来例に比べると、ポリマー使用量は両フローで０．２５ｋｇ／ｈと変わらなかったが、処理汚泥量に対する高分子凝集剤の注入率は、従来例では２．２％であるのに対し、本発明では１．９％となり、注入率として０．３ポイント低下している。薬品の注入率は単位乾燥汚泥重量あたりの重量比である。実施例１では、本発明では、単位乾燥汚泥重量あたりでみると、高分子凝集剤が約１４％節減できていることになる。
すなわち、本発明の脱水方法は、従来例に比べ、処理量が１８％向上しながら、高分子凝集剤は乾燥重量あたり約１４％節減することができる。 [Example 1]
(1) Conditions
i) Human waste surplus sludge was used as organic sludge. The sludge density | concentration of a sludge storage tank was 2.0 wt%, and the sludge supply amount from a sludge storage tank was set to 600 L / h. As the concentrator, a multi-disc type concentrator having a slit width of 1.0 mm was used. With this concentrator, 7 wt% concentrated sludge can be obtained. The concentrated sludge is put into a screw press having an outer cylinder with an inner diameter of 250 mm and a total length of 1000 mm. In this screw press, the diameter of the screen opening (opening diameter) is φ3.0 mm and the opening ratio is 40% in the entire outer cylinder. The polymer flocculant in the mixing tank is a cationic polymer (Ebagulose C104G; manufactured by Ebara Engineering Service Co., Ltd.). The water content of the dewatered cake by the screw press was set to 80%, and the rate of sludge leakage from the screw press was set to 10% of the sludge flowing into the screw press.
ii) Under the above conditions, the following two cases were subjected to a continuous test, and the amount of sludge to be dehydrated and the injection rate of the polymer flocculant relative to the amount of treated sludge were compared. The contents of the experiment are the following two cases.
(1) Case 1 (Invention): At the start of the experiment, the concentrator separation liquid is biologically processed and the dehydrator separation liquid is discharged out of the processing system (FIG. 10). It was set as the flow which returns a dehydrator separation liquid to a mixing tank as shown.
(2) Case 2 (conventional example): At the start of the experiment, the concentrator separation liquid is biologically processed and the dehydrator separation liquid is discharged out of the processing system (FIG. 10). It was set as the flow which returns a dehydrator separation liquid to the sludge storage tank 51 as shown.

(2) Results In the conventional example, due to the effect of returning the dehydrated separation liquid to the sludge storage tank, the dewatering amount was 11.3 (kg / h). In contrast, in the present invention, the amount of dewatering treatment was stabilized at 13.3 (kgDS / h), and the discharging capacity of the dewatered cake was improved by 18%. Furthermore, compared to the conventional example, the amount of polymer used was not changed to 0.25 kg / h in both flows, but the injection rate of the polymer flocculant with respect to the amount of treated sludge was 2.2% in the conventional example. On the other hand, in the present invention, it is 1.9%, and the injection rate is reduced by 0.3 points. The injection rate of the chemical is a weight ratio per unit dry sludge weight. In Example 1, in the present invention, the polymer flocculant can be reduced by about 14% in terms of the unit dry sludge weight.
That is, in the dehydration method of the present invention, the polymer flocculant can be reduced by about 14% per dry weight while the throughput is improved by 18% compared to the conventional example.

[Example 2]
In the conventional example, as shown in FIG. 11, the dewatered separated water is returned to the sludge storage tank 51 and the dewatered separated water is returned to the raw sludge tank. It is.
In Example 2- (1) to Example 2- (8), the processing flow of FIG. 1 was used. In Example 2- (1) to Example 2- (3), the sludge return destination is a mixing tank and a concentrator, and Example 2- (4) to Example 2- (8). Then, it is an Example at the time of adding a fibrous dehydration adjuvant.
<Conditions of Example 2>
i) Organic sludge: human waste surplus sludge, sludge concentration in sludge storage tank 2.0wt%
ii) Sludge supply amount: 0.6 m ³ / hr
iii) Polymer flocculant: Ebagulose C104G cationic polymer (product of Ebara Engineering Service Co., Ltd.)
iv) Concentrator: Multiple disk type concentrator, slit width 1.0 mm
v) The screw press has an outer cylinder inner diameter of 250 mm, an outer cylinder total length of 1000 mm, a screen opening diameter of φ3.0 mm, and an aperture ratio of 40%.
In Example 2- (4) to Example 2- (8), a fibrous dehydration aid was added to the mixing tank. The fibrous dehydrating auxiliary agent is an auxiliary agent mainly composed of cellulose having a fiber diameter of 10 μm and a fiber length of 5 mm. Table 4 shows the conditions and results of the conventional example and Example 2.

In the conventional example, since the dewatered separated water is returned to the sludge storage tank, the amount of sludge to be returned is included in the supplied sludge. In the conventional example, 20% of the amount of sludge supplied to the dewatering equipment was the amount of returned sludge, and the concentration was lowered, so that the actual treatment amount was Example 2- (1) to 2- (3 ) Decreased by 15%. Furthermore, the water content of the dehydrated cake was also reduced by 0.2 to 1.0 points in Examples 2- (1) to 2- (3) compared to the conventional example. The injection rate of the polymer flocculant per dry sludge amount is 1.9% to -DS in the present invention, and 2.2% to -DS in the conventional example, and is about 14% in terms of unit weight. The molecular flocculant can be saved.
In Example 2- (5) to Example 2- (7) in which the addition rate of the fibrous dehydration auxiliary was 3 to 10%, the return destination was the same mixing tank in Example 2- (1). In comparison, the amount of sludge treated was equivalent to 13.3 kg DS / h, and the moisture content of the cake was reduced by 6 to 12 points.

  In addition, the result of the Example which made the addition rate of the fibrous dehydration auxiliary agent 2.5% is equivalent to the result of Example 2- (1), and the addition rate of the fibrous dehydration auxiliary agent is 10.5. As a result of Example, the water content of the dehydrated cake was reduced, but the treatment amount was significantly reduced to 5.4 kg DS / h. This is because the fibrous dehydration aid is excessive, causing a “sludge and screw blade circulation” phenomenon in the screw press, and the dehydrated cake is not discharged smoothly. From this, it was judged that 3 to 10% per DS of the addition rate of the fibrous dehydration aid was an appropriate amount.

Example 3
Experiments were performed with the treatment flow shown in FIG. 1 to examine the fiber diameter and fiber length of a fibrous dehydration aid mainly composed of cellulose. Except for the fibrous dehydration aid, it is the same as Example 2. The dehydration separation water was returned to the mixing tank. The results are shown in Table 5.

When the fiber diameter is 10 μm and 30 μm and the fiber length is 5 stages as shown in Table 5, when the fiber length is 2 mm or less, the moisture content is the same as the polymer flocculant single treatment of Example 2- (1). There is no effect of adding a fibrous dehydration aid. However, in the fiber length range of 3 to 30 mm, the moisture content of the dehydrated cake is reduced by 4 to 8 points, and the effect is exhibited. When the fiber length was more than 30 mm and 32 mm, sludge circulation occurred with a screw press, and the treatment amount decreased by about 40% at maximum. In the experimental range, a fiber length of 3 to 30 mm is suitable.
When the fiber diameter is 4 μm, even when the fiber length is 3 to 30 mm, the moisture content of the dehydrated cake is reduced by about 2 to 3 points. In the experimental range, the fiber diameter is suitably 10 to 30 μm.

Example 4
Example 4 is an example in which an experiment was performed with the processing flow shown in FIG. The processing flow shown in FIG. 2 is different from the processing flow shown in FIG. 1 in that the mixing tank is installed in the preceding stage of the mixing tank. That is, a mixing tank is provided in front of the mixing tank, and polyferric sulfate is injected into the mixing tank as an inorganic flocculant. As the polymer flocculant, a liquid emulsion type cationic chemical (Ebagulose LEC204; manufactured by Ebara Engineering Service Co., Ltd.) was used. In Example 4- (1) to Example 4- (3), ferric polysulfate was injected into the mixing tank, and in Example 4- (4) to Example 4- (6), the mixing tank was used. Injected with polyferric sulfate and fibrous dehydration aid. The fibrous dehydrating auxiliary agent is an auxiliary agent mainly composed of cellulose having a fiber diameter of 10 μm and a fiber length of 5 mm. In Example 4- (7), the return destination was a mixing tank and a mixing tank, and the amount of the returned liquid was equal. Table 6 shows the conditions and results.

Implementation conditions common to Example 4- (1) to Example 4- (7) are as follows.
i) Organic sludge: human waste surplus sludge, sludge concentration in sludge storage tank 2.0wt%
ii) Sludge supply amount: 0.6 m ³ / hr
iii) Concentrator: Multiple disk type concentrator, slit width 1.0 mm
iv) The screw press has an inner diameter of 250 mm, an outer cylinder length of 1000 mm, and a screen opening diameter of φ3.0 mm.

In the case of Example 4- (1) to Example 4- (3) in which an inorganic flocculant was injected into the mixing tank, both the water content of dehydrated cake and the treatment amount were both Example 2- (1) to Example 2- (3). ) And a sludge recovery rate of 99% or more.
In addition, in the case of Example 4- (4) to Example 4- (7) in which an inorganic flocculant and a fibrous dehydration aid were added to the mixing tank, the water content of the dehydrated cake was Example 4- (1) to Implementation. It was lower than Example 4- (3), the sludge recovery rate was 99% or more, and the moisture content of the dehydrated cake could be reduced by at least 7 points due to the addition of the fibrous dehydration aid.

  Moreover, in Example 4- (4) to Example 4- (7), when the return destination of the dehydrated filtrate was a mixing tank, a mixing tank or a concentrator, and a mixing tank and a mixing tank, Example 2- (5 ) And 3- (2), no significant difference was found in the results of recovery rate, dehydrated cake moisture content, and treatment amount. In consideration of the results of Example 2- (1) to 2- (3) and Example 4- (1) to (3), the return destination is not only the mixing tank, the mixing tank, and each tank of the concentrator, Even if the tanks are returned to these tanks at the same time, there is no significant difference in operation, and the present invention can also be applied to a case where a plurality of tanks are used as return destinations.

Example 5
Example 5 is an example in which an experiment was performed with the processing flow shown in FIG. 3 and the processing flow shown in FIG.
The implementation conditions are as follows.
i) Organic sludge: A fibrous dehydration aid was added to the human waste treatment surplus sludge sludge storage tank. As the fibrous dehydrating auxiliary agent, an auxiliary agent mainly composed of cellulose having a fiber diameter of 10 μm and a fiber length of 5 mm was also added.
ii) Sludge supply amount: 0.6 m ³ / hr, sludge concentration in sludge storage tank 2.0 wt%
iii) Concentrator: Multiple disk type concentrator, slit width 1.0 mm
iv) The screw press has an inner diameter of 250 mm, an outer cylinder length of 1000 mm, and a screen opening diameter of φ3.0 mm.
v) Dehydrated filtrate return destination: Mixing tank

A polymer flocculant (Ebagulose C104G cationic polymer; product of Ebara Engineering Service Co., Ltd.) was injected into the mixing tank.
1) Table 7 shows the sludge recovery rate, dehydrated cake moisture content, and treatment amount when sludge to which a fibrous dehydration aid has been added is supplied and dehydrated. Comparative Example 1 is a case where no fibrous dehydration aid was added.

  In Example 5- (1) to Example 5- (3), the fibrous dehydration aid is directly added to the sludge storage tank, and the dehydrator is added in advance to the supply sludge. When supplied and dehydrated, when the amount of addition of the fibrous dehydration aid was varied, the moisture content of the dehydrated cake decreased in proportion to the amount of addition of the fibrous dehydration aid. In particular, when 5.0% to kg-DS or more was added, the water content of the dehydrated cake was 70 wt% or less. When the dehydrated filtrate is returned to the mixing tank, the concentrator, or the mixing tank and the concentrator, there is a large difference in the sludge recovery rate, dehydrated cake moisture content, and throughput depending on the return destination. There wasn't.

In addition, when the fibrous dehydration auxiliary agent addition rate was less than 3%, the moisture content of the cake was 75% or more, and there was no effect of addition. Furthermore, when the addition rate of the fibrous dehydrating auxiliary agent exceeded 10%, the sludge was circulated by the screw press, and the treatment amount was greatly reduced to 7.8 (kg-DS / h).
As in Example 2, the addition rate of the fibrous dehydration aid is in a range where 3 to 10% to -DS is suitable.

2) In addition to the conditions of Example 5- (1) to Example 5- (3), polyferric sulfate is injected into the mixing tank, and a liquid emulsion type cationic system is used as the polymer flocculant in the mixing tank. (Ebagulose LEC204; Ebara Engineering Service Co., Ltd. product) was used. This example is an example in which an experiment was conducted with the processing flow shown in FIG. Table 8 shows the sludge recovery rate, moisture content of the dehydrated cake, and treatment amount.

  In Example 5- (4) to Example 5- (6), when the sludge to which the fibrous dehydrating auxiliary was added in advance was supplied and dehydrated, the amount of the fibrous dehydrating auxiliary added was varied. The water content decreased in proportion to the amount of fibrous dehydration aid added. In particular, when 5.0% to kg-DS or more was added, the water content of the dehydrated cake was 70 wt% or less. When the dehydrated filtrate was returned to the mixing tank, the concentrator, or the mixing tank and the concentrator, there was no significant difference in the sludge recovery rate, dehydrated cake water content, and throughput.

  In addition, when the fibrous dehydration auxiliary agent addition rate was less than 3%, the moisture content of the cake was 75% or more, and there was no effect of addition. Furthermore, when the addition rate exceeded 10%, sludge circulation occurred in the screw press, and the treatment amount was significantly reduced to 7.8 (kg-DS / h). The addition rate of the fiber-like dehydration auxiliary is in the range of 3 to 10% to -DS as in Example 2.

Example 6
Example 6 is an example in which an experiment was performed with the processing flow shown in FIG. In this example, only the fibrous fibrous dehydration aid is added to the mixing tank.
The implementation conditions are as follows.
i) Organic sludge: human waste surplus sludge, sludge concentration in sludge storage tank 2.0wt%
ii) Sludge supply amount: 0.6 m ³ / hr
iii) Injection chemical: A fibrous dehydration aid was added to the mixing tank. The fibrous dehydrating auxiliary agent is an auxiliary agent mainly composed of cellulose having a fiber diameter of 10 μm and a fiber length of 5 mm. A polymer flocculant (Ebagulose C104G cationic polymer; product of Ebara Engineering Service Co., Ltd.) was injected into the mixing tank.
iv) Concentrator: Multiple disk type concentrator, slit width 1.0 mm
v) The screw press has an outer cylinder inner diameter of 250 mm, an outer cylinder total length of 1000 mm, a screen opening diameter of φ3.0 mm, and an aperture ratio of 40%.

1) Table 9 shows the water content of dehydrated cake and the treatment amount when only the fibrous dehydration aid is supplied and dehydrated in the mixing tank. In this example, the recovery rate was 99% or more under any conditions.

  In Example 6- (1) to Example 6- (4), when the sludge to which the fibrous dehydrating auxiliary was added in advance was supplied and dehydrated, the amount of the fibrous dehydrating auxiliary added was varied, and the dehydrated cake The water content decreased in proportion to the amount of fibrous dehydration aid added. In particular, when 5.0% to kg-DS or more was added, the water content of the dehydrated cake was 70 wt% or less. When the dehydrated filtrate was returned to the mixing tank, the concentrator, or the mixing tank and the concentrator, there was no significant difference in the sludge recovery rate, dehydrated cake water content, and throughput.

In addition, when the fibrous dehydration auxiliary agent addition rate was less than 3%, the moisture content of the cake was 75% or more, and there was no effect of addition. Furthermore, when the addition rate exceeded 10%, sludge circulation occurred in the screw press, and the treatment amount was significantly reduced to 7.8 (kg-DS / h).
As in Example 2, the addition rate of the fibrous dehydration aid is in a range where 3 to 10% to -DS is suitable.

Example 7
Example 7 is an example in which an experiment was performed with the processing flow shown in FIG. That is, it is a flow that introduces the dewatered separation liquid from the screw press 4 into the dewatered liquid separation tank 15 and returns the concentrated sludge of the precipitation tank to the mixing tank 1 and / or the mixing tank 2 and / or the concentrator 3. In the dewatering separation liquid settling tank 15, the concentrated sludge leaking from the screw press is precipitated and separated, and the concentrated sludge can be returned.
The implementation conditions are as follows.
i) Organic sludge: human waste surplus sludge, sludge concentration in sludge storage tank 2.0wt%
ii) Sludge supply amount: 0.6 m ³ / hr
iii) Injection chemical: A fibrous dehydration aid was added to the mixing tank. The fibrous dehydrating auxiliary agent is an auxiliary agent mainly composed of cellulose having a fiber diameter of 10 μm and a fiber length of 5 mm. A polymer flocculant (Ebagulose C104G cationic polymer; product of Ebara Engineering Service Co., Ltd.) was injected into the mixing tank.
iv) Concentrator: Multiple disk type concentrator, slit width 1.0m
v) The screw press has an outer cylinder inner diameter of 250 mm, an outer cylinder total length of 1000 mm, a screen opening diameter of φ3.0 mm, and an aperture ratio of 40%.
vi) Dehydration liquid settling tank: 1m in diameter, 1m in effective water depth

A dehydrating separator settling tank was installed for Example 2- (6), Example 4- (5), Example 5- (2), Example 5- (5), and Example 6- (2). The operation of returning the precipitated and concentrated sludge to the mixing tank was conducted 5 cases. Examples will be Example 7- (1) to Example 7- (5). Table 10 shows the sludge recovery rate, the moisture content of the dehydrated cake, and the treatment amount.
In Example 7- (1) to Example 7- (5), the dehydrated filtrate is settled and separated, and only the solid content is returned to generate a margin in the processing capacity of the screw press, and the processing amount is about 10%. In addition to increasing, the moisture content of the cake decreased by 0.9 to 1.2 points. In addition, when a dehydrating separation liquid settling tank is installed in a batch system and returned to the sedimentation / concentrated sludge mixing tank, the processing capacity is improved 1.1 times compared to the case without a dehydrating separation liquid precipitation tank. did.

Experiments of Examples 8 to 11 were performed by changing the aperture diameter of the screen of the screw press. The experimental conditions common to these examples are as follows.
1) Organic sludge: human waste surplus sludge 2) The screw press has an inner diameter (D) of the outer cylinder of 250 mm, a total length (L) of 1000 mm, and L = 4D
3) A mixing tank for injecting the polymer flocculant was provided, and the dehydrated filtrate of the screw press was not returned. The injection rate of the polymer flocculant is 1.9 (% vs. -DS).
4) The performance evaluation of the screw press was performed by measuring the moisture content of the dehydrated cake (wt%), the amount of dehydrated cake discharged (kg-DS / h), and the amount of sludge leaked as dehydrated separation liquid (kg-DS / h). The actual dehydration rate (%) defined in the equation was used.
Actual treatment rate of dehydration (%) = [Dehydrated cake discharge / (Dehydrated cake discharge + Leakage of sludge)] × 100 (4)
5) The performance of the screw press is highly practical when the moisture content of the dehydrated cake is 80% or less and the actual treatment rate of dehydration is 70% or more (Evaluation A), and the moisture content of the dehydrated cake is 80%. Or when the actual treatment rate of dehydration is less than 70%, there is no practicality (evaluation B).

Example 8
Example 8 is an example in which an experiment was conducted with the processing flow shown in FIG. 1, but without adding a fibrous dehydration aid to the mixing tank 2, sludge was introduced directly into the screw press 4 from the mixing tank 2. The performance of the screw press was evaluated without returning the dehydrated separation liquid. The conditions are as follows.
1) A polymer flocculant (Ebagulose C104G cationic polymer; EBARA Engineering Service Co., Ltd. product) was injected into the mixing tank. The sludge concentration in the sludge storage tank is 2.1 wt%, and the amount of sludge supplied to the screw press is 600 L / h.
2) In the screw press, the hole diameter was the same with respect to the full length (L) of the outer cylinder. In this case, the hole area ratio is 30 to 50%. The conditions and results are shown in Table 11. In Example 8, Evaluation A was Example 8- (3), Example 8- (4), and Example 8- (5). In this case, the punching hole diameter is 2 to 3 mm.

Example 9
Example 9 is an example in which an experiment was performed with the processing flow shown in FIG. 1, but without adding a fibrous dehydration aid to the mixing tank 2, sludge was passed from the mixing tank 2 via the concentrator 3. An experiment for evaluating the performance of the screw press was conducted without introducing the dehydrated separation liquid into the screw press. The conditions are as follows.
1) The sludge concentration in the sludge storage tank was 2.8 wt%, and the amount of sludge supplied to the screw press was 600 L / h.
2) A polymer flocculant (Ebagulose C104G cationic polymer; Ebara Engineering Service Co., Ltd. product) was injected into the mixing tank.
3) In the screw press, the punching hole diameter was the same with respect to the overall length (L) of the outer cylinder. In this case, the hole area ratio is 30 to 50%. The conditions and results are shown in Table 12.
The implementation conditions are as follows.
i) A polymer flocculant (Ebagulose C104G cationic polymer; EBARA Engineering Service Co., Ltd. product) was injected into the mixing tank.
ii) The concentrator used was a multi-disc type concentrator with a slit mesh width of 1.0 mm.
iii) In the screw press, a punching screen (punching metal) having the same opening diameter with respect to the overall length (L) of the outer cylinder was used. In this case, the hole area ratio is 30 to 50%. The conditions and results are shown in Table 12.
In Example 9, Evaluation A is Example 9- (2), Example 9- (3), Example 9- (4), Example 9- (5), and Example 9- (6). In Examples recognized as Evaluation A, the punching hole diameter is 1.5 to 4 mm. Compared with the result of Example 8, the application range of the aperture diameter is expanded by using a concentrator in the case of Example 9.

Example 10
Example 10 is an example in which an experiment was performed with the processing flow shown in FIG. 2, a fibrous dehydration aid was added to the mixing tank 1, and a polymer flocculant was injected into the mixing tank 2, The sludge was passed from the mixing tank 2 through the concentrator 3 and then introduced into the screw press, and the performance of the screw press was evaluated without returning the dehydrated separation liquid. The conditions are as follows.
1) A polymer flocculant (Ebagulose C104G cationic polymer; EBARA Engineering Service Co., Ltd. product) was injected into the mixing tank.
2) In the screw press, a punching screen (punching metal) having the same opening diameter with respect to the overall length (L) of the outer cylinder was used. In this case, the hole area ratio is 30 to 50%. Conditions and results are shown in Table 13.
The implementation conditions are as follows.
i) A fibrous dehydration aid was added to the mixing tank. The fibrous dehydrating auxiliary agent is an auxiliary agent mainly composed of cellulose having a fiber diameter of 10 μm and a fiber length of 5 mm. The addition rate of the fibrous dehydration aid was 5 (% vs. DS).
ii) A polymer flocculant (Ebagulose C104G cationic polymer; EBARA Engineering Service Co., Ltd. product) was injected into the mixing tank. The sludge concentration in the sludge storage tank is 2.8 wt%, and the amount of sludge supplied to the screw press is 650 L / h.
iii) As the concentrator, a multi-disk type concentrator with a slit mesh width of 1.0 mm was used.
3) In the screw press, a punching screen (punching metal) having the same opening ratio with respect to the overall length (L) of the outer cylinder was used. In this case, the hole area ratio is 30 to 50%. Conditions and results are shown in Table 13.
In Example 10, evaluation A is Example 10- (2)-Example 10- (6), and an aperture diameter is 1.5-4 mm in this case. Compared to Example 8, the application range of the aperture diameter is expanded by using a concentrator. Furthermore, the moisture content of the dehydrated cake is lower than that in Example 9.

Example 11
Example 11 is an example in which an experiment was conducted with the processing flow shown in FIG. 1 in the same manner as in Example 9. However, the fiber dehydration aid was not added to the mixing tank, and the screw press 4 directly from the mixing tank 2. Sludge was introduced into the slab, and the performance of the screw press was evaluated without returning the dehydrated separation liquid.
The conditions are as follows.
1) A polymer flocculant (Ebagulose C104G cationic polymer; EBARA Engineering Service Co., Ltd. product) was injected into the mixing tank.
2) With the screw press, the hole diameter of the punching screen at a distance D (250 mm) from the front end where the sludge supply port is located is changed with respect to the overall length (L) of the outer cylinder, and the remaining 3D (750 mm) has a hole diameter of 2 mm. It was. In this case, the hole area ratio is 30 to 50%. The conditions and results are shown in Table 14.
In Example 11, even at a distance D (250 mm) from the front end, no significant difference was observed from the result of Example 8, and the opening diameter of the front end of the screw press greatly contributes to the discharge amount of the dehydrated cake. In addition, evaluation A is Example 11- (2)-Example 11- (6), and an aperture diameter is 1.5-4 mm in this case.

Example 12
Example 12 is an example in which an experiment was conducted with the processing flow shown in FIG. 1 in the same manner as in Example 8. However, the fiber dehydration auxiliary was not added to the mixing tank, and the screw press 4 was directly added from the mixing tank 2. Sludge was introduced into the slab, and the performance of the screw press was evaluated without returning the dehydrated separation liquid.
The conditions are as follows.
1) A polymer flocculant (Ebagulose C104G cationic polymer; EBARA Engineering Service Co., Ltd. product) was injected into the mixing tank.
2) In the screw press, the distance D (250 mm) from the front end portion where the sludge supply port is located is changed with respect to the outer cylinder full length (L), and the remaining 3D (750 mm) has an opening diameter of 2 mm. In this case, the hole area ratio is 30 to 50%. The conditions and results are shown in Table 15.
In Example 12, even at a distance of 2D from the front end (500 mm), no significant difference was found from the result of Example 8, and the opening diameter of the front end of the screw press greatly contributes to the discharge amount of the dehydrated cake. In addition, evaluation A is Example 12- (2)-Example 12- (6), and is a hole diameter 1.5-4 mm in this case.

  As mentioned above, although embodiment and the Example of this invention were described, this invention is not limited to the said embodiment and Example, The range of the technical idea described in the claim and the specification and drawing Various modifications are possible.

FIG. 1 is a schematic view showing a first embodiment of an organic sludge dewatering apparatus according to the present invention. FIG. 2 is a schematic view showing a second embodiment of the organic sludge dewatering apparatus according to the present invention. FIG. 3 is a schematic view showing a third embodiment of the organic sludge dewatering apparatus according to the present invention. FIG. 4 is a schematic view showing a fourth embodiment of the organic sludge dewatering apparatus according to the present invention. FIG. 5 is a schematic view showing a fifth embodiment of the organic sludge dewatering apparatus according to the present invention. FIG. 6 is a schematic view showing a sixth embodiment of the organic sludge dewatering apparatus according to the present invention. FIG. 7 is an external view of a screw press applied to the organic sludge dewatering apparatus of the present invention shown in FIGS. 1 to 6. FIG. 8 is a schematic view showing an example of a cylindrical outer cylinder of a screw press. FIGS. 9A, 9B and 9C are partially enlarged views showing a part of a screen (punching screen) constituting a cylindrical outer cylinder of a screw press. FIG. 10 is a diagram showing a flow of a conventional sludge apparatus. FIG. 11 is a diagram showing a flow of a conventional sludge apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mixing tank 2 Mixing tank 3 Concentrator 4 Screw press 5 Dehydration separation liquid receiving tank 6 Dehydration separation water return pump 7 Fibrous dehydration auxiliary agent supply device 15 Dehydration separation liquid precipitation tank 41 Cylindrical outer cylinder 42 Screw shaft 43 Screw blade 41h Open Hole 41a Sludge supply port 41b Dehydrated cake outlet 41h Open hole 41p Screen (punching screen)
44 Dehydrated cake discharge part 44a Dehydrated cake outlet 45 Dehydrated separation water outlet 50 Water treatment facility 51 Sludge storage tank 52 Sludge supply pump 53 Supply line 54 Flow meter

Claims (13)

A mixing step in which a polymer flocculant or a polymer flocculant and a fibrous dehydrating auxiliary agent are added to and mixed with organic wastewater or organic sludge containing suspended matter,
A concentration step of concentrating the coagulated sludge generated in the mixing step to obtain a separated liquid and concentrated sludge;
A dehydration step of dehydrating the concentrated sludge obtained in the concentration step with a screw press to obtain a dehydrated cake and a dehydrated separation liquid,
A method for dewatering organic sludge, wherein the dehydrated separation liquid obtained in the dehydration step is returned to the mixing step and / or the concentration step. A dehydrating aid mixing step of adding and mixing an inorganic flocculant and / or a fibrous dehydrating aid to organic wastewater or organic sludge containing suspended matter;
A mixing step of adding a polymer flocculant to the organic waste water or organic sludge discharged from the dehydrating aid mixing step,
A concentration step of concentrating the coagulated sludge generated in the mixing step to obtain a separated liquid and concentrated sludge;
A dehydration step of dehydrating the concentrated sludge obtained in the concentration step with a screw press to obtain a dehydrated cake and a dehydrated separation liquid,
A method for dewatering organic sludge, wherein the dehydrated separation liquid obtained in the dehydration step is returned to the dehydration aid mixing step and / or the mixing step and / or the concentration step.   The organic matter according to claim 1 or 2, wherein the dehydrated separation liquid is subjected to solid-liquid separation, and the obtained sludge side is returned to the dehydration aid mixing step and / or the mixing step and / or the concentration step. Method for dewatering activated sludge. A mixing tank in which a polymer flocculant or a polymer flocculant and a fibrous dehydrating auxiliary agent are added to and mixed with organic wastewater or organic sludge containing suspended matter,
A concentrator for concentrating sludge produced in the mixing tank to obtain a separated liquid and concentrated sludge;
A screw press to obtain a dehydrated cake and a dehydrated separated liquid by dehydrating the concentrated sludge obtained by the concentrator;
An organic sludge dewatering apparatus comprising: a dewatering separation liquid obtained by the screw press; and a return pipe for returning the dewatered separation liquid to the mixing tank and / or the concentrator. A mixing tank in which an inorganic flocculant and / or a fibrous dehydration aid is added to and mixed with organic wastewater or organic sludge containing suspended solids,
A mixing tank in which a polymer flocculant is added to and mixed with organic wastewater or organic sludge discharged from the mixing tank;
A concentrator for concentrating sludge produced in the mixing tank to obtain a separated liquid and concentrated sludge;
A screw press to obtain a dehydrated cake and a dehydrated separated liquid by dehydrating the concentrated sludge obtained by the concentrator;
An organic sludge dewatering apparatus comprising: a dewatering separation liquid obtained by the screw press; and a return pipe for returning the dewatering separation liquid to the mixing tank and / or the mixing tank and / or the concentrator.   A solid-liquid separation device that separates the dehydrated separation liquid into a solid and a liquid is provided, and the sludge obtained by the solid-liquid separation device is returned to the mixing tank and / or the mixing tank and / or the concentrator through the return pipe. The organic sludge dewatering device according to claim 5 or 6, wherein the dewatering device is an organic sludge.   The organic sludge dewatering apparatus according to any one of claims 4 to 6, wherein means for adding the fibrous dewatering auxiliary agent is provided in the mixing tank and / or the mixing tank.   The organic sludge according to any one of claims 4 to 6, wherein means for adding the fibrous dewatering auxiliary agent is provided in a sludge storage tank installed in the preceding stage of the mixing tank or in the preceding stage of the mixing tank. Dehydration equipment. A cylindrical outer cylinder, a screw shaft disposed concentrically with the outer cylinder inside the outer cylinder, and a screw blade fixed to the screw shaft;
The outer cylinder is provided with a screen having a plurality of openings for discharging the dehydrated separation liquid, and has a first half portion having a supply port for organic waste water or organic sludge containing suspended matters, and a dehydrated cake It is composed of the latter half part with the exit part of
The organic sludge characterized by having an opening area of 1.8 to 12.6 mm ² at least at the opening having a length equal to the inner diameter of the outer cylinder from the end on the supply port side Screw press for dehydration.   The screw press according to claim 9, wherein the opening has a diameter of about 1.5 mm to about 4.0 mm in terms of a perfect circle. The apertures, screw press according to claim 9, wherein the opening area is 3.1~7.1mm ^2.   The screw press according to claim 11, wherein the opening has a diameter of about 2.0 mm to about 3.0 mm in terms of a perfect circle.   An organic sludge dewatering apparatus comprising a multiple disk type concentrator having a slit width of 0.5 mm to 1.5 mm in a preceding stage of the screw press according to any one of claims 9 to 12.

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