JP2016097373A - Sludge dehydration treatment method and sludge dehydration treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sludge dehydration treatment method capable of reducing initial cost and running cost and further capable of swiftly performing the dehydration treatment of sludge.SOLUTION: Provided is a sludge dehydration treatment method where primarily sedimented sludge 19 obtained by subjecting the water 11 to be treated containing fibrous material to gravitational sedimentation in a final sedimentation tank 31 and surplus sludge 21 obtained by subjecting the same to gravitational sedimentation in a final sedimentation tank 35 are mixed into mixed sludge 23; thereafter, the mixed sludge 23 is subjected to dehydration treatment by a dehydration machine 67. The primarily sedimented sludge 19 and the surplus sludge 21 are mixed so that the content of the fibrous material in the mixed sludge 23 reaches 20% or higher.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sludge dewatering method in which dewatering treatment is performed by mixing primary sludge obtained by gravity sedimentation of water to be treated containing fibrous materials in a first sedimentation basin and surplus sludge obtained by gravity sedimentation in a final sedimentation basin, and The present invention relates to a sludge dewatering system.

  The treated water flowing into the sewage treatment plant varies in inflow and components in the treated water due to daily fluctuations, seasonal fluctuations, weather, and the like.

  In the first sedimentation basin, the amount and components of the initial sludge are affected, but in the final sedimentation basin, the treated water flows in through the reaction tank. Few.

  Primary sedimentation sludge is mainly composed of inorganic components such as solid organic matter and earth and sand, and generally has good dewaterability.

  On the other hand, surplus sludge is composed of polysaccharides, proteins, and nucleic acids secreted by microorganisms, and is known to have extremely poor dewaterability.

  The initial sludge generated in the first sedimentation basin and the surplus sludge generated in the final sedimentation basin are concentrated to a certain concentration by the respective concentration equipment provided in order to improve the efficiency in the dehydration process.

  Each concentrated sludge is mixed at a predetermined ratio and supplied to a dehydrator, and the dehydrated cake produced by the dehydrator is incinerated or disposed of in landfill.

  In order to reduce the running cost for transporting and disposing of the dehydrated cake, it is desired to stably produce a dehydrated cake having a low water content.

  It has long been known that mixed sludge is mixed with fibrous materials, sawdust, rice husks, and other plant materials as a dehydrating aid, and has been practiced in many sewage treatment plants.

  Thus, when a fibrous material (dehydration aid) is mixed and dehydrated in the mixed sludge, a dehydrated cake having a low water content is obtained, and in the case of pressure dehydration, the delamination property of the dehydrated cake is improved. .

  However, since a large amount of dehydration aid has to be prepared, the running cost increases, and since a storage and supply facility for the dehydration aid has to be installed, the initial cost increases.

  In addition, in the concentrating facility, the primary sedimentation sludge is retained for 1 to 3 days. During this residence period, the organic content in the primary sedimentation sludge may rot and change to a sludge having poor dewaterability.

  The fibrous material contained in the first settling sludge also rots in the same way, and sometimes changes to a property that does not function as a dehydration aid.

  Furthermore, there has been a problem that the running cost for maintenance and management of the concentration facility and the initial cost for plant construction increase.

  Therefore, the fiber content is separated and recovered from the primary sedimentation sludge that is raw sludge generated in the initial sedimentation basin of the sewage treatment process, and the recovered fiber content is added to the difficult-to-dehydrate sludge such as excess sludge or digested sludge for dehydration treatment. Has been proposed (see, for example, Patent Document 1).

  In addition, it has also been proposed to perform a dehydration treatment by adjusting the mixing ratio of the initial settling sludge and excess sludge (see, for example, Patent Document 2 and Patent Document 3).

  Thus, running cost can be reduced by using the fiber part isolate | separated and collect | recovered from the initial settling sludge as a dehydration aid.

JP-A 61-268400 JP 2002-011500 A JP 2004-278950 A

  However, in the sludge dewatering method and the sludge dewatering system described in Patent Document 1, it is necessary to prepare equipment for separating and recovering the fiber from the first settled sludge, and a storage facility for storing the fiber is required. There is a problem of becoming.

  In addition, the sludge dewatering method and the sludge dewatering system described in Patent Document 2 are intended to reduce the phosphorus concentration by shortening the contact time between the primary sedimentation sludge and the excess sludge.

  In addition, in Patent Document 2, there is no description of mixing the first sludge with good dewatering property with the excess sludge with poor dewatering property, and there is a lack of concreteness regarding the improvement of the dewatering property of the unconcentrated mixed sludge. is there.

  Patent Document 3 describes a technique for adjusting the mixing ratio of primary sedimentation sludge and excess sludge, and specifically, inorganic components in the solid content of the mixed sludge of primary sedimentation sludge and excess sludge. And the mass ratio of the organic component to 10:90 to 40:60.

  The organic component is mainly composed of “protein”, “carbohydrate”, “lipid”, etc., and the fiber content is contained in “carbohydrate”. Therefore, the technology of Patent Document 3 uses the fiber content in the mixed sludge. In order to limit, it is the technique which adjusts the mixing ratio of primary sludge and excess sludge.

  However, the organic component described in Patent Document 3 is described as a factor that deteriorates the dewaterability, and specifically, the initial sedimentation sludge generated in the first sedimentation basin has a low content of organic components and thus is dewaterable. However, it is described that the final sedimentation sludge generated in the final sedimentation basin is poor in dewaterability due to the high content of organic components.

  In Patent Document 3, there is no description or suggestion of a fibrous material used as a dehydrating aid for improving dewaterability.

  This invention was made by paying attention to the fact that the fibrous material contained in the initial settling sludge functions as a dewatering aid, and can reduce initial costs and running costs for sewage treatment plants and sludge treatment. The present invention provides a sludge dewatering method and a sludge dewatering system capable of performing sludge dewatering at high speed.

  The sludge dewatering method of the present invention is a mixture of sludge mixed with initial sludge obtained by gravity sedimentation of water to be treated containing fibrous material in a first sedimentation basin and surplus sludge obtained by gravity sedimentation in a final sedimentation basin. Then, the sludge dewatering method of dewatering the mixed sludge with a dehydrator, wherein the initial sludge and the surplus sludge are adjusted so that the content of the fibrous material in the mixed sludge is 20% or more. It is characterized by mixing.

  The sludge dewatering treatment system of the present invention includes a first sedimentation basin that gravity-precipitates water to be treated containing fibrous materials, a reaction tank that biologically treats primary treatment water supplied from the first sedimentation basin, and the reaction tank A final sedimentation basin that gravity settles the treated water supplied from the wastewater, discharges the supernatant water, an initial sedimentation sludge supply device that feeds the primary sedimentation sludge settled in the first sedimentation basin to the mixing tank, and sedimentation in the final sedimentation basin The surplus sludge supply device that supplies the surplus sludge to the mixing tank, the mixing tank in which the initial sludge and the surplus sludge are supplied by the initial sludge supply device and the surplus sludge supply device, and the mixing In the mixed sludge supply device for supplying the mixed sludge in the tank to the dehydrator, the dehydrator for dehydrating the mixed sludge supplied by the mixed sludge supply device, and the first settling sludge in the first settling sludge supply device The fiber Based on the output of the fibrous material content measuring device for measuring the content of the fibrous material and the fibrous material content measuring device, the content of the fibrous material in the mixed sludge in the mixing tank is 20%. As mentioned above, it has the control apparatus which controls the said initial sedimentation sludge supply apparatus and the said excess sludge supply apparatus, It is characterized by the above-mentioned.

  The sludge dewatering treatment system of the present invention includes a first sedimentation basin for gravity-precipitation of water to be treated containing fibrous materials, a primary treatment water supplied from the first sedimentation basin, a reaction tank for biological treatment, A final sedimentation basin that gravity settles the treated water supplied from the reaction tank and discharges the supernatant water, an initial sedimentation sludge supply device that supplies the primary sedimentation sludge precipitated in the first sedimentation tank to the mixing tank, and the final sedimentation tank Surplus sludge supply device for supplying the surplus sludge precipitated in the mixing tank, the mixing tank in which the initial sludge and the excess sludge are supplied by the initial sludge supply device and the excess sludge supply device, A mixed sludge supply device for supplying mixed sludge in the mixing tank to a dehydrator, the dehydrator for dehydrating the mixed sludge supplied by the mixed sludge supply device, and the fibers in the mixed sludge in the mixing tank Condition The content rate of the fibrous material in the mixed sludge in the mixing tank is 20% or more based on the output of the fibrous material content rate measuring device for measuring the content rate of the fibrous material and the fibrous material content rate measuring device. It has the control apparatus which controls the said initial settling sludge supply apparatus and the said surplus sludge supply apparatus so that it may become.

  According to the sludge dewatering method and the sludge dewatering system of the present invention, the first settling sludge and the excess sludge are mixed so that the content of the fibrous material in the mixed sludge is 20% or more. The sludge properties for performing can be maintained.

  Therefore, it is possible to supply the initial settling sludge whose dewaterability changes every day due to daily fluctuations, etc. directly to the dehydrator without concentrating it at the front stage of the dehydrator, and it is possible to perform the rapid sludge treatment at the sewage treatment plant. In addition, the concentration equipment can be reduced.

  In addition, the initial cost and running cost can be reduced by eliminating the need to bring in and add a dehydration aid from the outside.

It is a block diagram which shows the structure of the sludge dehydration processing system which is 1st Example of this invention. It is a graph which compares toilet paper and the fibrous material collect | recovered from the first settling sludge. It is a reference microscope picture which shows the fibrous material which primary sedimentation sludge contains. It is a graph which shows the relationship between a fibrous material content rate and a dehydrated cake moisture content. It is a block diagram which shows the structure of the sludge dehydration processing system which is 2nd Example of this invention. It is a block diagram which shows the structure of the sludge dehydration processing system which is 3rd Example of this invention. It is a block diagram which shows the structure of the principal part of the sludge dehydration processing system which is 4th Example of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a sludge dewatering treatment system according to a first embodiment of the present invention.

  In FIG. 1, the sludge dewatering treatment system 1 is a reaction for biologically treating a first settling basin 31 for gravity-precipitation of water to be treated 11 containing fibrous materials and a primary treated water 13 supplied from the first settling basin 31. The tank 33, the treated water 15 supplied from the reaction tank 33 is gravity-precipitated, and the final sedimentation basin 35 that discharges the supernatant water 17 to a river or the like, and the initial sedimentation sludge 19 that has settled in the first sedimentation basin 31 are mixed tanks 55. The first settling sludge supply device 37 to be supplied to the final settling tank 35, the excess sludge supply device 43 for supplying the excess sludge 21 settled in the final settling tank 35 to the mixing tank 55, the first settling sludge supply device 37 and the excess sludge supply device 43 The mixing tank 55 to which the settling sludge 19 and the excess sludge 21 are supplied, the mixed sludge supply device 57 for supplying the mixed sludge 23 of the mixing tank 55 to the coagulation mixing tank 63, and the mixed sludge supply device 57 to mix the mixed sludge. The dewatering cake 29 is generated by dewatering the coagulant mixing tank 63 to which the coagulant mixing tank 63 is supplied, the coagulant supplying device 65 for supplying the coagulant 25 to the coagulant mixing tank 63, and the coagulated sludge 27 supplied from the coagulant mixing tank 63. A dehydrator (for example, a screw press) 67, a fibrous material content measuring device 73 for measuring the content of the fibrous material in the initial sludge 19 in the initial sludge supply device 37, and this fibrous material content Based on the output of the measuring apparatus 73, the control apparatus which controls the initial sedimentation sludge supply apparatus 37 and the excess sludge supply apparatus 43 so that the content rate of the fibrous material in the mixed sludge 23 in the mixing tank 55 may be 20% or more. 75.

  And the sludge dewatering processing system 1 may be provided with the surplus sludge return apparatus 49 which returns a part of the surplus sludge 21 to the reaction tank 33, as shown with a dashed-dotted line.

  The first settling sludge supply device 37 described above includes, for example, a supply pipe 39 having one end connected to the lower part (bottom) of the first settling basin 31 and the other end connected to the mixing tank 55, and in the middle of the supply pipe 39. The pump 41 is provided and sucks the first settling sludge 19 in the first settling basin 31 and pumps it into the mixing tank 55.

  Moreover, the surplus sludge supply apparatus 43 is provided in the middle of this supply pipe 45, for example, the supply pipe 45 by which one end was connected to the lower part (bottom) of the final sedimentation tank 35, and the other end was connected to the mixing tank 55. The pump 47 is configured to suck the excess sludge 21 in the final sedimentation basin 35 and pump it into the mixing tank 55.

  The surplus sludge return device 49 has a supply pipe 51 having one end connected to the supply pipe 45 upstream of the pump 47 of the surplus sludge supply apparatus 43 and the other end connected to the reaction tank 33, and the supply pipe 51 The pump 53 is provided in the middle and sucks the excess sludge 21 in the first sedimentation tank 31 and pumps it into the reaction tank 33.

  The mixed sludge supply device 57 is provided in the middle of the supply pipe 59, for example, a supply pipe 59 having one end connected to the lower part (bottom) of the mixing tank 55 and the other end connected to the coagulation mixing tank 63. And a pump 61 that sucks the mixed sludge 23 in the mixing tank 55 and pumps it into the agglomeration mixing tank 63.

  Further, the reaction tank 33 corresponds to an aeration tank that blows air and decomposes organic substances by the action of microorganisms, and an OD tank of the OD method (oxidation ditch method).

  Next, each component (equipment) will be described.

  First, in the first settling basin 31, the treated water 11 that has flowed in is separated by gravity, the solid content with a high specific gravity settles, and the solid content and the liquid with a low specific gravity (primary treated water 13) go to the reaction tank 33 in the next stage. The solid content that has been sent and settled to the bottom is dehydrated as the first sedimentation sludge 19 in the subsequent stages.

  The treated water 11 contains a large amount of fibrous material.

  Most of the fibrous materials contained in the water 11 to be treated are found to be fibrous materials derived from toilet paper having a fiber length of 0.1 mm to 5 mm and a fiber diameter of 1 μm to 50 μm. doing.

  FIG. 2 is a graph comparing the toilet paper and the fibrous material collected from the initial settling sludge, where the horizontal axis is the fiber length (mm) and the vertical axis is the ratio (%) of the fiber length. The fiber content obtained by dissolving toilet paper in water is compared with the fiber content recovered from the first settling sludge at the sewage treatment plant.

  From the comparison results in FIG. 2, it was found that the fiber distribution (fiber length, ratio) in the sewage sludge is very similar to that of toilet paper.

  Moreover, it turns out that it is preferable to set it as the fiber length 0.1mm-5mm as a property of the fiber collect | recovered.

  FIG. 3 is a reference photomicrograph showing the fibrous material contained in the initial settling sludge.

  As can be seen from FIG. 3, the fibrous material contained in the initial sedimentation sludge 19 was found to be within the range of 1 μm to 50 μm, with no variation in fiber diameter, similar to toilet paper.

  From these, the property distribution of the fibrous material contained in the first settling sludge 19 is very similar to the fiber property of toilet paper, and can be determined to have the same properties as the fiber content of toilet paper, It turns out that it is preferable as a dehydration aid.

  In addition to the fibrous material derived from toilet paper, the fibrous material contained in the treated water 11 includes a fibrous material derived from plants or a fibrous material derived from food residue, If it is in a subdivided state, it functions as a dehydration aid.

  The initial settling sludge 19 contains 40% to 60% of a fibrous material in solid content ratio.

  And depending on the scale of the treatment plant, in the first settling basin 31, the treated water 11 is retained for 1 to 2 hours.

  Next, in the reaction tank 33, activated sludge (sludge containing a large amount of aerobic microorganisms) is added to the primary treated water 13 supplied from the first settling basin 31, and air is blown in and stirred.

  Microorganisms in the activated sludge are propagated by the air (oxygen) and the organic matter in the primary treated water 13 to reduce the organic matter (dirt) in the primary treated water 13, and the activated sludge forms flocs and easily settles. It becomes a state and flows out to the next stage.

  And depending on the scale of the treatment plant, in the reaction tank 33, the primary treated water 13 is retained for 6 hours to 10 hours.

  Next, in the final sedimentation basin 35, the treated water 15 mixed with activated sludge supplied from the reaction tank 33 is retained to perform gravity precipitation.

  The supernatant water 17 of the final sedimentation basin 35 is subjected to advanced treatment as necessary and discharged to a river or the like.

  The surplus sludge 21 that has settled at the bottom of the final sedimentation basin 35 is dehydrated in the subsequent stage.

  It is known that this excess sludge 21 is composed of polysaccharides, proteins, and nucleic acids secreted by microorganisms, and has extremely poor dehydration properties.

  And depending on the scale of the treatment plant, the treated water 15 is retained in the final sedimentation basin 35 for 3 hours to 4 hours.

  Next, the mixing tank 55 uniformly mixes the initial settling sludge 19 sent by the first settling sludge supply device 37 and the excess sludge 21 sent by the excess sludge supply device 43 with a stirring mechanism, and mixed sludge. 23.

  As described above, the purpose of uniformly stirring the primary sedimentation sludge 19 and the excess sludge 21 is to uniformly disperse the fibrous material contained in the primary sedimentation sludge 19 so that the fibrous material functions as an agglomeration nucleus and dehydrates. This is because it sometimes functions as a dehydrating aid having an effect of forming a water channel.

  Next, the coagulation mixing tank 63 mixes the mixed sludge 23 supplied by the mixed sludge supply device 57 and the coagulant 25 supplied from the coagulant supply device 65 with uniform stirring, and is stabilized by the dehydrator 67. Thus, an agglomerated floc that can be dewatered is formed.

  Next, the dehydrator 67 dehydrates the coagulated sludge 27 supplied from the coagulation / mixing tank 63 to generate a dehydrated cake 29 having a stable low water content.

  Since the present invention does not require a concentration facility and the time required from the time when the treated water 11 flows into the settling basin 31 to the time when it is supplied to the dehydrator 67 is generally less than 6 hours, the first settling sludge 19 and There is no change in the properties of the fibrous material contained in the initial settling sludge 19, and it is possible to dehydrate sludge that maintains good dewaterability with a highly functional dewatering aid.

  Conventionally, as factors affecting dewaterability, the concentration of sludge, the organic content, and the fiber content (fibrous matter, dewatering aid) are known.

  As for the degree of the influence, it has been found that the fiber content has a great influence on the dewaterability compared to the sludge concentration and the organic content.

  If the fiber content is 20% or more in the coagulated sludge 27 (mixed sludge 23), the dehydrated cake 29 having a low water content can be efficiently generated without concentrating the sludge before the dehydration step. .

  Next, the fibrous material content measuring device 73 is in the middle of the branch pipe 69 with one end connected to the supply pipe 39 upstream of the pump 41 of the initial settling sludge supply apparatus 37 and the other end connected to the reaction tank 33. The content rate of the fibrous material (dehydration aid) contained in the initial settling sludge 19 extracted from the initial settling sludge supply device 37 is measured.

  If the first settling sludge 19 is not branched (supplied) to the branch pipe 69 due to the suction of the pump 41, a pump controlled by the control device 75 is provided in the middle of the branch pipe 69, and the initial settling in the branch pipe 69 is performed. It is preferable that the sludge 19 is supplied.

  As an example of measuring the content rate of the fibrous material, the initial settling sludge 19 is supplied onto the filter, the fine impurities are washed away, and the fibrous material remains.

  And when measuring the content rate of a fibrous material by weight, the weight of the fibrous material which remained on the filter is measured, and a content rate is computed.

  In addition, when measuring the content of fibrous material by pressure loss, gas is blown onto the fibrous material remaining on the filter, and the content is calculated by measuring pressure on the upstream side and downstream side of the filter. Alternatively, the liquid is supplied to the fibrous material remaining on the filter, and the content rate is calculated from the passing speed, the passing amount, and the like of the liquid.

  Moreover, when measuring the content rate of a fibrous material with an image, the content rate is calculated by photographing the fibrous material remaining on the filter and performing image analysis (luminance, translucency, etc.).

  In addition, when the treated water 11 is gravity-precipitated in the first sedimentation basin 31, about 97% of the fibrous material in the treated water 11 settles and settles in the first sedimentation basin 31, and the remaining 3% of the fibrous material. Is decomposed in the reaction tank 33, the fibrous material is not supplied to the final sedimentation basin 35.

  And the ratio of the fibrous material which initially settles in the sedimentation basin 31 and solids other than a fibrous material is 40 (%): 60 (%)-60 (%): 40 (%).

  Moreover, the ratio of the fibrous material which settles in the final sedimentation basin 35 and solids other than a fibrous material is 0 (%): 100 (%).

  And when primary sludge 19 which is easy to be subject to seasonal and time fluctuations is mixed with surplus sludge 21, even when there are few fibrous materials in primary sludge 19, it is highly likely that 20% or more can always be secured, and 20% If the mixed sludge 23 contains the above fibrous material, it can be dehydrated without depending on the sludge concentration, and the water content can be sufficiently reduced by the dehydrator 67.

  FIG. 4 is a graph showing the relationship between the fibrous material content and the dehydrated cake water content.

  The sludge is dehydrated by changing the content of the fibrous material in the mixed sludge 23 mixed without concentrating the primary sludge 19 and the surplus sludge 21. The fiber content of 10% is 3% and 20%. The cake moisture content has decreased by about 6% in terms of the fibrous content.

  For example, the fibrous material of the initial sludge 19 is 40%, the solid material other than the fibrous material is 60%, the fibrous material of the excess sludge 21 is 0%, and the solid material other than the fibrous material is 100%. When the primary sludge 19 and the excess sludge 21 are mixed at a ratio of 1: 0.8, the ratio of the fibrous material of the mixed sludge 23 is (40/180) × 100 = 22 (%), and the dehydrator 67 can sufficiently reduce the moisture content.

  Generally, dehydrated cake generated at a sewage treatment plant is easily transported and has a moisture content of 80% or less, and the running cost for post-treatment such as incineration and landfill can be reduced.

  And considering the property change of the water 11 to be treated, when the fibrous material content in the mixed sludge 23 is 20% or more, the dehydrated cake water content can be suppressed to 80% or less.

  Next, operation | movement of the sludge dehydration processing system 1 is demonstrated.

  First, the water to be treated 11 containing fibrous materials is first gravity-deposited in the first sedimentation basin 31, and the initial sedimentation sludge 19 is sedimented in the first sedimentation basin 31.

  Then, the primary treated water 13 of the first sedimentation tank 31 is supplied to the reaction tank 33 and biologically treated in the reaction tank 33.

  Then, the treated water 15 in the reaction tank 33 is supplied to the final sedimentation basin 35 and gravity-precipitated in the final sedimentation basin 35, the excess sludge 21 is settled in the final sedimentation basin 35, and the supernatant water 17 is discharged to a river or the like. .

  In this way, when dewatering the first settling sludge 19 generated when the sewage is treated and the excess sludge 21, first, the first settling sludge 19 is sucked from the first settling basin 31 by controlling the pump 41. Then, the first settling sludge 19 is supplied to the mixing tank 55.

  In this way, when the initial settling sludge 19 is supplied to the mixing tank 55, a part of the initial settling sludge 19 is supplied to the fibrous material content measuring device 73 via the branch pipe 69. The measurement device 73 measures the content of the fibrous material in the first settling sludge 19, and the content is sent to the control device 75.

  The initial settling sludge 19 that has been used for the measurement of the content of the fibrous material is supplied to the initial settling basin 31.

  And the control apparatus 75 to which the signal of the content rate was supplied from the fibrous material content rate measuring device 73 which measured the content rate of the fibrous material in the first settling sludge 19 is the fibrous material in the mixed sludge 23 in the mixing tank 55. The pump 41 of the first settling sludge supply device 37 and the pump 47 of the surplus sludge supply device 43 are controlled so that the content rate of the product becomes 20% or more.

  Then, the mixing tank 55 uniformly mixes the supplied primary sludge 19 and excess sludge 21 to form a mixed sludge 23 (aggregated sludge), thereby forming an aggregated floc.

  The mixed mixed sludge 23 is supplied to the coagulation mixing tank 63 by the mixed sludge supply device 57.

  For example, the flocculant 25 is supplied from the flocculant supply device 65 controlled by the control device 75 to the flocculent mixing tank 63 to which the mixed sludge 23 is supplied. Are uniformly mixed to form agglomerated sludge 27 and supplied to the dehydrator 67 while forming agglomerated floc.

  The dehydrator 67 to which the coagulated sludge 27 is supplied dehydrates the coagulated sludge 27 and generates a dehydrated cake 29.

  According to the first embodiment of the present invention, since the fibrous material in the initial settling sludge 19 is used as a dewatering aid, the running cost can be reduced and the sludge can be concentrated before the dewatering step. The sludge can be dehydrated quickly.

  FIG. 5 is a block diagram showing the configuration of the sludge dewatering system according to the second embodiment of the present invention. The same or corresponding parts as those in FIG.

  The sludge dewatering treatment system 1A of the second embodiment is different from the sludge dewatering treatment system 1 of the first embodiment in that one end is connected to the supply pipe 39 downstream of the pump 41 of the initial settling sludge supply device 37, A fibrous material content measuring device 73 is provided in the middle of the branch pipe 69 </ b> A whose other end is connected to the mixing tank 55.

  The sludge dewatering system 1A of the second embodiment operates in the same manner as the sludge dewatering system 1 of the first embodiment described above, and obtains the same effects as the sludge dewatering system 1 of the first embodiment. Can do.

  FIG. 6 is a block diagram showing the configuration of the sludge dewatering treatment system according to the third embodiment of the present invention. The same reference numerals are given to the same or corresponding parts as in FIGS.

  The sludge dewatering treatment system 1B of the third embodiment is different from the sludge dewatering treatment systems 1 and 1A of the first embodiment or the second embodiment in that one end is connected to, for example, the lower part (bottom) of the mixing tank 55. Then, the pump 71 and the fibrous material content measuring device 73 are provided from the upstream side to the downstream side in the drawing pipe 69B whose other end is connected to the mixing tank 55.

  The sludge dewatering treatment system 1B of the third embodiment operates in the same manner as the sludge dewatering treatment systems 1 and 1A of the first embodiment or the second embodiment described above, and the sludge dewatering treatment system 1B of the first embodiment or the second embodiment. The same effect as the sludge dewatering treatment system 1 or 1A can be obtained.

  FIG. 7 is a block diagram showing the configuration of the main part of the sludge dewatering treatment system according to the fourth embodiment of the present invention. The same or corresponding parts as those in FIGS. 1, 5, and 6 are denoted by the same reference numerals. Description is omitted.

  The sludge dewatering treatment system 1C of the fourth embodiment is different from the sludge dewatering treatment systems 1, 1A, 1B of the first to third embodiments in that the mixed sludge 23 is directly transferred from the mixing tank 55 to the dehydrator 67A. It is supplied and dehydrated with a dehydrator (for example, screw press, belt press, centrifugal dehydrator, etc.) 67A.

  In the sludge dewatering treatment systems 1, 1 </ b> A, 1 </ b> B of the first to third embodiments, the mixed sludge 23 and the flocculant 25 are mixed in the flocculation mixing tank 63 in order to ensure the dehydration of the dehydrator 67. Yes.

  However, since the mixed sludge 23 in the mixing tank 55 is 20% or more of the fibrous material that is a dehydration aid, the mixed sludge 23 forms an aggregated floc by being mixed uniformly.

  Therefore, by supplying the mixed sludge 23 from the mixing tank 55 to the dewatering machine 67A and dehydrating the mixed sludge 23 with the dewatering machine 67A, the dewatered cake 29 having a stable low water content can be generated.

  The sludge dewatering treatment system 1C of the fourth embodiment operates in the same manner as the sludge dewatering treatment systems 1, 1A, 1B of the first to third embodiments described above, and the first to third embodiments. The same effect as the sludge dewatering treatment system 1, 1A, 1B of the example can be obtained.

  Furthermore, the sludge dewatering treatment system 1C of the fourth embodiment can reduce initial costs and running costs by eliminating the need to install a coagulation / mixing tank and a coagulant supply device.

  In the embodiment described above, the primary sedimentation sludge 19 or the excess sludge 21 is provided in the preceding stage of the mixing tank 55 in preparation for the case where the amount of primary sedimentation sludge 19 and surplus sludge 21 generated in the first sedimentation basin 31 and the final sedimentation basin 35 is large. You may provide the adjustment tank which stores temporarily.

  Thus, when providing an adjustment tank, the amount of the initial sedimentation sludge 19 or the excess sludge 21 sent from the adjustment tank to the mixing tank 55 is 20% or more in the content of the fibrous material in the mixed sludge 23 in the mixing tank 55. It is necessary to control by the control apparatus 75 so that it may become.

  In addition, when the sludge property of the primary sedimentation sludge 19 and the property change of the fibrous material contained in the primary sedimentation sludge 19 can be managed, the primary sedimentation sludge supply device 37 is provided with a concentration facility for the primary sedimentation sludge 19. Also good.

  The sludge dewatering treatment method and the sludge dewatering treatment system according to the present invention effectively utilize as a dewatering aid the fibrous material contained in the first settling sludge in which the water to be treated flowing into the sewage treatment plant is gravity-precipitated. It becomes a self-recovery treatment plant that procures dewatering aids from unnecessary materials and performs sludge treatment, and it can generate dehydrated cake with a stable low moisture content, and at the same time, environmentally friendly sewage dewatering that makes dewatering cake processing cheap and easy. It becomes a processing method and a sewage dehydration processing system.

DESCRIPTION OF SYMBOLS 1 Sludge dewatering system 1A Sludge dewatering system 1B Sludge dewatering system 1C Sludge dewatering system 11 To-be-treated water 13 Primary treated water 15 Treated water 17 Supernatant water 19 Primary sludge 21 Surplus sludge 23 Mixed sludge 25 Coagulant 27 Aggregated sludge 29 Dewatered cake 31 First sedimentation basin 33 Reaction tank 35 Final sedimentation basin 37 Primary sedimentation sludge supply device 39 Supply pipe 41 Pump 43 Surplus sludge supply device 45 Supply pipe 47 Pump 49 Surplus sludge return device 51 Supply pipe 53 Pump 55 Mixing tank 57 Mixing Sludge supply device 59 Supply pipe 61 Pump 63 Coagulation mixing tank 65 Coagulant supply device 67 Dehydrator 67A Dehydrator 69 Branch pipe 69A Branch pipe 69B Intake pipe 71 Pump 73 Fibrous material content rate measuring device 75 Controller

Claims (6)

After mixing the initial sludge in which the water to be treated containing the fibrous material is gravity-precipitated in the first sedimentation basin and the surplus sludge that has been gravity-precipitated in the final sedimentation basin to make a mixed sludge, the mixed sludge is dehydrated A sludge dewatering method of dewatering with
Mixing the initial settling sludge and the excess sludge so that the content of the fibrous material in the mixed sludge is 20% or more,
A sludge dewatering method characterized by the above. A first sedimentation basin for gravity-treating the water to be treated containing fibrous materials;
A primary treatment water supplied from the first sedimentation basin, a reaction tank for biological treatment;
A final sedimentation basin that gravity settles the treated water supplied from the reaction tank and discharges the supernatant water;
An initial settling sludge supply device for supplying the initial settling sludge precipitated in the first settling basin to the mixing tank;
Surplus sludge supply device for supplying surplus sludge precipitated in the final sedimentation tank to the mixing tank;
The mixing tank in which the initial settling sludge and the excess sludge are supplied by the initial settling sludge supply device and the excess sludge supply device;
A mixed sludge supply device for supplying the mixed sludge in the mixing tank to the dehydrator;
The dehydrator for dehydrating the mixed sludge supplied by the mixed sludge supply device;
A fibrous material content rate measuring device that measures the content rate of the fibrous material in the initial settled sludge in the initial settled sludge supply device;
Based on the output of the fibrous material content rate measuring device, the initial settling sludge supply device and the excess sludge supply device so that the content rate of the fibrous material in the mixed sludge in the mixing tank is 20% or more. And a control device for controlling
A sludge dewatering system characterized by that. A first sedimentation basin for gravity-treating the water to be treated containing fibrous materials;
A primary treatment water supplied from the first sedimentation basin, a reaction tank for biological treatment;
A final sedimentation basin that gravity settles the treated water supplied from the reaction tank and discharges the supernatant water;
An initial settling sludge supply device for supplying the initial settling sludge precipitated in the first settling basin to the mixing tank;
Surplus sludge supply device for supplying surplus sludge precipitated in the final sedimentation tank to the mixing tank;
The mixing tank in which the initial settling sludge and the excess sludge are supplied by the initial settling sludge supply device and the excess sludge supply device;
A mixed sludge supply device for supplying the mixed sludge in the mixing tank to the dehydrator;
The dehydrator for dehydrating the mixed sludge supplied by the mixed sludge supply device;
A fibrous material content measuring device for measuring the content of the fibrous material in the mixed sludge in the mixing tank;
Based on the output of the fibrous material content rate measuring device, the initial settling sludge supply device and the excess sludge supply device so that the content rate of the fibrous material in the mixed sludge in the mixing tank is 20% or more. And a control device for controlling
A sludge dewatering system characterized by that. In the sludge dewatering treatment system according to claim 2 or claim 3,
The dehydrator is any one of a screw press, a belt press, and a centrifugal dehydrator.
A sludge dewatering system characterized by that. In the sludge dewatering treatment system according to any one of claims 2 to 4,
The fibrous material has a fiber length of 0.1 mm to 5 mm and a fiber diameter of 1 μm to 50 μm.
A sludge dewatering system characterized by that. In the sludge dewatering treatment system according to any one of claims 2 to 5,
The fibrous material is a fibrous material derived from toilet paper,
A sludge dewatering system characterized by that.