JP2007229545A - Sludge concentration facility and method for concentrating sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide sludge concentration facility which is compact, also easily adjustable and capable of efficiently concentrating most suitable flocculated sludge. <P>SOLUTION: A sludge flocculation apparatus 3 of the sludge concentration facility 1 including a belt-type concentration machine 6 for concentrating flocculated sludge supplied from the sludge flocculation apparatus 3 mixing sludge with a flocculant and loaded with the flocculant comprises a line mixer 4 mixing the sludge with the flocculant and generating the flocculated sludge and a flocculation mixing tank 5 receiving the flocculated sludge discharged from the line mixer 4 through a sludge supply line 2 and agitating the received flocculated sludge to grow it. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of a sludge concentration facility, and more particularly, a sludge concentration facility and a sludge that are compact and can effectively concentrate even a sludge with a small amount of flocculant added. It relates to a concentration method.

Sludge generated from a sewage treatment plant or the like is treated by being concentrated or dewatered by a sludge concentration facility, a sludge dewatering facility, or the like. Usually, a polymer flocculant (hereinafter referred to as a flocculant) is added to sludge and mixed (mixed), and agglomerated sludge containing flocs aggregated by mixing (mixing) the flocculant is concentrated. As the sludge concentrating equipment, for example, there is a belt type concentrator that concentrates by an endless belt having a water permeability function that is suspended by a pair of rollers, and the sludge in the sludge concentrating process by this belt type concentrator Mixing (mixing) with a flocculant is performed by a line mixer (line chemical injection device) or a flocculent mixing tank alone as a sludge aggregating device having a stirring function (for example, see Patent Document 1).
JP 2004-24963 A

  According to the sludge aggregating apparatus (aggregation mixing tank or line mixer) of the sludge concentration facility according to the conventional example, it is considered useful because the sludge and the aggregating agent can be mixed. However, in the coagulation mixing tank, mixing of the sludge and the coagulant usually requires a time of about 3 minutes, so that a large capacity is required. Further, in the line mixer, the mixing of the sludge and the flocculant is performed in a short time (about 10 seconds). However, since the adjustment range of the stirring strength is narrow, it is difficult to adjust the optimum flocculent sludge.

  That is, in the case of the sludge concentration facility according to the conventional example, the flocculant is supplied to the flocculation mixing tank or the line mixer. The coagulation mixing tank requires a large space for mixing sludge and coagulant and forming the coagulated sludge, so it is difficult to make the sludge concentration equipment compact and it is difficult to reduce the initial cost of the sludge concentration equipment. . Moreover, in a line mixer, there exists a problem that it is difficult to adjust optimal coagulation sludge and it is difficult to exhibit the best performance of a concentrator.

  Accordingly, an object of the present invention is to provide a sludge concentrating facility and a sludge concentrating method capable of effectively concentrating with an optimum coagulated sludge that is compact and easily adjustable.

  The present invention has been made in view of the above circumstances, and therefore, the means employed by the sludge concentrating facility according to claim 1 of the present invention to solve the above-mentioned problems is a sludge that mixes sludge and a flocculant. In the sludge concentration equipment provided with a concentrator for concentrating the coagulated sludge added with the coagulant supplied from the coagulator, the sludge coagulator mixes the sludge and the coagulant and generates a coagulated sludge. The coagulation sludge discharged from the line mixer through the sludge supply line is received, and the coagulation sludge tank is provided for stirring and growing the received coagulated sludge.

  The means adopted by the sludge concentrating equipment according to claim 2 of the present invention is the sludge concentrating equipment according to claim 1, wherein the concentrator is an endless shape having a dehydrating function that is suspended and circulated by a pair of rollers. It is a belt type concentrator provided with a belt.

  The means adopted by the sludge concentration facility according to claim 3 of the present invention is the sludge concentration facility according to claim 2, wherein the agglomeration mixing tank supports the pair of rollers on the agglomerated sludge supply port side of the belt. The belt-type concentrator is configured integrally with the main body frame, and is configured to cause the agglomerated sludge to flow substantially horizontally in the direction of the belt.

  The means employed by the sludge concentration facility according to claim 4 of the present invention is the sludge concentration facility according to any one of claims 2 and 3, wherein the coagulation mixing tank is retained for a predetermined time. The aggregated sludge is generated and raised, and the raised aggregated sludge is supplied onto the belt.

  The means adopted by the sludge concentration method according to claim 5 of the present invention is to supply agglomerated sludge produced by adding and mixing a flocculant to the sludge flowing into this line mixer to the agglomeration mixing tank by a line mixer, The agglomerated sludge is agitated in an agglomeration mixing tank and is allowed to grow for a predetermined time while being raised, and is then supplied to a concentrator to be concentrated.

  The means employed by the sludge concentration method according to claim 6 of the present invention is a belt-type concentrator in which the concentrator comprises an endless belt having a dehydrating function that is looped around a pair of rollers. And the agglomerated sludge is supplied onto the belt.

  The means employed by the sludge concentration method according to claim 7 of the present invention is the sludge concentration method according to claim 6, while stirring the agglomerated sludge on the belt while stirring in the agglomeration mixing tank, and The agglomerated sludge that has been allowed to stay for a predetermined period of time while being raised is allowed to flow substantially horizontally toward the belt.

  The means employed by the sludge concentration method according to claim 8 of the present invention is the sludge concentration method according to any one of claims 5 to 7, wherein the residence time of the aggregated sludge in the aggregation mixing tank is: It is characterized by being 20 to 60 seconds.

  According to the sludge concentration equipment according to claim 1 of the present invention or the sludge concentration method according to claim 5, the stirring strength can be adjusted in the agglomeration mixing tank, so that the agglomerated sludge can be grown to the optimum agglomerated sludge. it can. Moreover, since the residence time for producing agglomerated sludge is reduced by vigorous stirring of the line mixer, the capacity of the agglomeration mixing tank can be reduced. Accordingly, since the capacity of the sludge aggregating apparatus is reduced, the sludge concentrating equipment can be made compact and it can contribute to power saving.

  According to the sludge concentration facility according to claim 2 of the present invention or the sludge concentration method according to claim 6, the mixed agglomerated sludge is directly supplied from the agglomeration mixing tank to an endless belt having a dehydrating function and concentrated. Therefore, the aggregated sludge is difficult to be crushed and the amount of the flocculant added to the sludge can be reduced, so that an excellent effect of greatly contributing to the reduction of the sludge concentration treatment cost can be obtained.

  According to the sludge concentration equipment according to claims 3 and 4 of the present invention or the sludge concentration method according to claim 7, the coagulation mixing tank is a belt type that supports the pair of rollers on the coagulation sludge supply port side of the belt. It is constructed integrally with the main body frame of the concentrator, and the agglomerated sludge is supplied to the belt after flowing substantially horizontally in the direction of the belt. Accordingly, the amount of flocculant added can be reduced because the flocculated sludge is not easily crushed. Furthermore, since a sludge supply apparatus is unnecessary, sludge concentration equipment can be made compact.

  According to the sludge concentration method according to claim 8 of the present invention, the residence time of the coagulation sludge in the coagulation mixing tank is 20 to 60 seconds, so the capacity of the coagulation mixing tank can be reduced. Accordingly, since the capacity of the sludge aggregating apparatus is reduced, the sludge concentrating equipment can be made compact and it can contribute to power saving.

  A sludge concentration facility according to an embodiment of the present invention will be described with reference to the accompanying drawings, taking as an example a sludge concentration facility including a belt-type concentrator that filters and concentrates sludge. FIG. 1 is a schematic configuration explanatory view of a sludge concentration facility according to an embodiment of the present invention.

  The code | symbol 1 shown in FIG. 1 is the sludge concentration equipment which concerns on embodiment of this invention. The sludge concentrating facility 1 receives sludge sent from a sludge storage tank (not shown), adds a flocculant to the received sludge and mixes it, and the aggregated sludge discharged from the line mixer 4 A sludge aggregating device 3 comprising a coagulation / mixing tank 5 received through a sludge supply line 2 is provided.

  The line mixer 4 constituting one side of the sludge aggregating apparatus 3 has a well-known configuration in which a baffle plate whose opening degree can be adjusted is provided in a pipe. Moreover, the coagulation mixing tank 5 which comprises the other of this sludge aggregation apparatus 3 is comprised so that it may mention later. That is, the agglomeration mixing tank 5 includes a tank body 5a through which the sludge supply line 2 for supplying the agglomerated sludge discharged from the line mixer 4 communicates. The tank body 5a is constructed integrally with a body frame 6a of a belt type concentrator 6 which will be described later, and a stirring wheel 5b rotated by a stirring motor M via a drive belt is arranged near the bottom. It is installed.

  The belt type concentrator 6 is provided with an endless belt 6f having a water permeability function (dehydration function) that is looped over a pair of rollers 6d and 6e. More specifically, in the belt type concentrator 6, the driving roller 6d on the side of the sludge discharge port 6c of the belt 6f having a water permeability function overflows the coagulated sludge from the coagulation mixing tank 5 (flows in a substantially horizontal direction). In this way, the filtered water filtered from the agglomerated sludge by the belt 6f and the washed waste water after washing the belt 6f are collected at the bottom. It is a gravity type belt-type filter provided with 6 g of bread-shaped water collection tank parts which drain by water. Note that the concentrated sludge that has been concentrated and discharged from the sludge discharge port 6c of the belt type concentrator 6 until, for example, the solid content concentration reaches about 4% is sent to the next step.

  Hereinafter, the operation mode of the sludge concentration equipment 1 according to the embodiment of the present invention will be described. That is, in the case of the sludge aggregating apparatus 3 of the sludge concentrating facility 1 according to the embodiment of the present invention, as described above, the line mixer 4 for mixing the sludge and the aggregating agent, and the belt type on the downstream side of the line mixer 4 The concentrator 6 is integrally formed on the main body frame 6a and the sludge supply port 6b side, accepts the aggregated sludge discharged from the line mixer 4 through the sludge supply line 2, and agitate the received aggregated sludge. And an agglomeration mixing tank 5 equipped with a stirring wheel 5b.

  Therefore, according to the sludge aggregating apparatus 3 of the sludge concentration facility 1 according to the embodiment of the present invention, the agglomerated sludge discharged from the line mixer 4 is agitated by the agitating wheel 5b in the agglomeration mixing tank 5. The sludge and the flocculant can be mixed (mixed) with high efficiency to form agglomerated sludge.

  Incidentally, the time required for mixing (mixing) until the sludge and the flocculant are completely mixed is about 3 minutes in the case of only the coagulation mixing tank. However, in the case of the sludge aggregating apparatus 3 of the sludge concentration facility 1 according to the embodiment of the present invention in which the line mixer 4 and the agglomeration mixing tank 5 are combined, the residence time of the agglomerated sludge in the agglomeration mixing tank 5 is 20 to 60. The time is preferably 20 to 30 seconds from the viewpoint of the second, the growth of the coagulated sludge and the equipment cost, and it has been found that the time required for mixing the sludge and the coagulant is greatly shortened. Therefore, since the capacity | capacitance of the coagulation mixing tank 5 can be made into a very small capacity compared with the coagulation mixing tank concerning a prior art example, the sludge concentration equipment 1 can be made compact. Regarding the mixed state of the sludge and the flocculant, the agglomerated sludge supplied to the belt 6f from the sludge supply port 6b of the belt type concentrator 6 is collected, and the collected agglomerated sludge is observed with a microscope to obtain the agglomerated sludge (floc). ) Was checked by checking the generation status.

  According to the sludge aggregating apparatus 3 of the sludge concentrating facility 1 according to the embodiment of the present invention, the length of the sludge supply line 2 from the line mixer 4 of the sludge aggregating apparatus 3 to the belt type concentrator 6 is set. Further, as described above, the volume of the agglomeration mixing tank 5 can be reduced. Therefore, it is possible to greatly contribute to the downsizing of the sludge concentration facility 1 and to greatly contribute to the reduction of the initial cost of the sludge concentration facility 1.

  Further, the agglomerated sludge received from the line mixer 4 is agitated to form agglomerated sludge, and the agglomerated sludge is raised and fluidized in a substantially horizontal direction to be supplied onto the belt. Since there is almost no pressure and speed at the time, the coagulated sludge is not easily crushed, and the coagulation degree of the coagulated sludge does not need to be so strong. Therefore, since the addition amount of the flocculant can be reduced, it is possible to obtain an excellent effect that it can greatly contribute to the reduction of the sludge concentration treatment cost.

  Hereinafter, using the sludge concentration facility 1 having the above-described configuration, the concentration rate of concentrated sludge and the SS (solid matter) recovery rate with respect to the concentration rate of coagulated sludge were changed by changing the injection rate. As a result of this investigation test, the horizontal axis indicates the drug injection rate (the flocculant injection rate, the unit is wt% vs. TS (the acronym for Total Solid)), and the left vertical axis indicates the concentration of concentrated sludge (unit; 2), and the right vertical axis represents the SS recovery rate (unit: wt%), as shown in Fig. 2 of the sludge concentration result explanatory graph diagram. The distance between the roller shafts is about 3 m, the belt width is about 2 m, and the belt is a filter cloth made of polyester fiber.

Note that the black circle, white circle, black triangle, and white triangle marks in FIG. 2 indicate the following, respectively.
(1) Black circle mark: Concentrated sludge concentration with respect to the chemical injection rate of the coagulated sludge obtained by coagulating sludge in both the line mixer and the coagulation mixing tank of the sludge coagulation apparatus (referred to as the concentrated sludge concentration according to the example)
(2) White circle mark: Concentrated sludge concentration with respect to the chemical injection rate of the coagulated sludge obtained by coagulating sludge with the line mixer of the sludge coagulator (referred to as the concentrated sludge concentration according to the comparative example)
(3) Black triangle mark; SS recovery rate relative to the chemical injection rate of the coagulated sludge obtained by coagulating the sludge in both the line mixer and the coagulation mixing tank of the sludge aggregation device (referred to as the SS recovery rate according to the example)
(White triangle mark; SS recovery rate with respect to the chemical injection rate of coagulated sludge obtained by coagulating sludge with a line mixer of the sludge coagulating device (referred to as SS recovery rate according to comparative example)

Moreover, the test conditions of this investigation test are as follows.
(1) Target sludge: Surplus sludge from the sewage treatment plant (sludge from the final sedimentation basin)
(2) Supply sludge concentration: 0.21-0.31 wt%
(3) Sludge treatment amount: 15 m ³ / h
(4) Type of flocculant; C-6797H (cationic flocculant, manufacturer: Shinko Environmental Maintenance Co., Ltd.)
(5) Belt speed: 5.7 m / min
(6) Inclination angle of belt; 2 °
(7) Residence time of coagulated sludge; 30 seconds

  As is well understood from FIG. 2, the concentrated sludge concentration according to the comparative example indicated by white circles is 3.9 wt% when the chemical injection rate is 0.28 wt% vs. TS, and the chemical injection rate is 0.2. It is 3.1 wt% when 19 wt% vs TS. On the other hand, the concentrated sludge concentration according to the example indicated by the black circles is 4.1 wt% when the drug injection rate is 0.28 wt% vs. TS, and even if the drug injection rate is reduced to 0.18 wt. Concentrated sludge concentration has hardly decreased.

According to this example, even if the chemical injection rate is 0.18 wt% vs. TS, the concentrated sludge concentration is superior to that in the comparative example where the chemical injection rate is 0.28 wt% vs. TS, and is indicated by a triangle mark. Regarding the SS recovery rate, the present example is superior to the comparative example. More specifically, the chemical injection rate is reduced by 0.07 wt% (0.25 wt% −0.18 wt%). In other words, in the case of the present embodiment, the amount of the flocculant used is 28% (0.07 ÷ 0.25 × 100) lower than that of the comparative example, which greatly reduces the sludge concentration cost. It has been suggested that it can contribute.
Also, with respect to the SS recovery rate, the present example is superior to the comparative example by about 2% but slightly better.

  In the case of the sludge concentration facility 1 according to the embodiment of the present invention, the case where the concentrator is a belt type concentrator has been described as an example. However, not limited to this form, the technical idea of the present invention can also be applied to a dehydrator such as a belt press, a centrifugal dehydrator and a screw press, and a concentrator such as a screw concentrator. From the viewpoint that the coagulation and mixing tank can be integrated with the main body of the concentrator, two sheets are stacked on the sludge discharge destination side of the concentrated sludge of the belt type concentrator, and the concentrated sludge is sandwiched between the rollers. It can apply suitably with respect to the belt press dehydrator which spin-dry | dehydrates and makes it a sludge cake. Also, for centrifugal dehydrator that spins the bowl at high speed and dewaters sludge with its centrifugal force, and screw concentrator (screw press dehydrator) that concentrates (dehydrates) sludge while rotating the outer cylinder screen and screw shaft at different speeds. However, since the production | generation of optimal coagulation sludge becomes easy and a sludge coagulation apparatus can be made compact and power-saving, it is thought that it can apply suitably. Therefore, the scope of application of the technical idea of the present invention is not limited to the sludge concentration facility according to the above embodiment.

It is typical structure explanatory drawing of the sludge concentration equipment which concerns on embodiment of this invention. The horizontal axis represents the drug injection rate (the flocculant injection rate, the unit is wt% vs. TS (total solid)), the left vertical axis is the concentrated sludge concentration (unit: wt%), and the right vertical It is a sludge concentration result explanatory graph figure which takes SS recovery rate (unit; wt%) as an axis | shaft.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sludge concentration equipment 2 ... Sludge supply line 3 ... Sludge aggregation apparatus 4 ... Line mixer 5 ... Coagulation mixing tank, 5a ... Tank main body, 5b ... Stirrer wheel 6 ... Belt type concentrator (gravity belt filter), 6a ... body frame, 6b ... sludge supply port, 6c ... sludge discharge port, 6d ... driving roller, 6e ... driven roller, 6f ... belt, 6g ... water collecting tank M: stirring motor

Claims (8)

  In the sludge concentration equipment provided with a concentrator for concentrating the coagulated sludge added with the coagulant supplied from the sludge coagulator for mixing the sludge and the coagulant, the sludge coagulator mixes the sludge and the coagulant. The sludge comprising: a line mixer for generating agglomerated sludge; and a flocculation mixing tank for receiving the agglomerated sludge discharged from the line mixer via a sludge supply line and stirring the grown agglomerated sludge to grow. Concentration equipment.   2. The sludge concentrating apparatus according to claim 1, wherein the concentrator is a belt type concentrator comprising an endless belt having a dehydrating function that is circulated by being laid around a pair of rollers.   The agglomeration mixing tank is configured integrally with a body frame of a belt-type concentrator supporting the pair of rollers on the agglomerated sludge supply port side of the belt, and causes the agglomerated sludge to flow substantially horizontally in the direction of the belt. The sludge concentration equipment according to claim 2, wherein the sludge concentration equipment is configured as described above.   4. The agglomeration mixing tank is configured to generate and raise agglomerated sludge while staying for a predetermined time, and to supply the agglomerated sludge raised to the belt. The sludge concentration equipment as described in any one of items.   The flocculent sludge produced by adding and mixing flocculant to the sludge flowing into the line mixer is supplied to the flocculent mixing tank by the line mixer, and the flocculent sludge is stirred and raised in the flocculent mixing tank. A sludge concentration method characterized in that the slurry is allowed to stay for a predetermined time to grow and then supplied to a concentrator for concentration.   The concentrator is a belt-type concentrator provided with an endless belt having a dehydrating function that is circulated by being laid on a pair of rollers, and supplies the coagulated sludge onto the belt. The sludge concentration method according to claim 5.   When supplying the agglomerated sludge onto the belt, the agglomerated sludge that has been allowed to grow for a predetermined period of time while stirring and rising in the agglomeration mixing tank is allowed to flow substantially horizontally toward the belt. The sludge concentration method according to claim 6.   The sludge concentration method according to any one of claims 5 to 7, wherein the residence time of the coagulated sludge in the coagulation mixing tank is 20 to 60 seconds.

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