JP3636355B2

JP3636355B2 - Sludge concentration equipment

Info

Publication number: JP3636355B2
Application number: JP19865799A
Authority: JP
Inventors: 栄一石垣; 方康西野; 雅義片山; 謙三菅谷
Original assignee: Ishigaki Co Ltd
Current assignee: Ishigaki Co Ltd
Priority date: 1999-07-13
Filing date: 1999-07-13
Publication date: 2005-04-06
Anticipated expiration: 2019-07-13
Also published as: JP2001025617A

Description

【０００１】
【発明の属する技術分野】
この発明は、下水処理場や廃水処理場等で発生する汚泥の濃縮装置に関し、特に、走行自在に配設した吸水性のある無端状のろ布を原液中に浸漬させ、吸水したろ布を濃縮槽外で脱水して原液を濃縮させる装置に関する。
【０００２】
【従来の技術】
下水処理において発生する汚泥は、有機物の増加により濃縮性が悪くなっており、所定の濃度が得難い状況にある。このため、重い汚泥を沈殿させて上澄液を分離する重力濃縮や、遠心力を利用して重い汚泥と液分を分離する遠心分離濃縮、あるいは、圧縮空気を用いて汚泥を押上げて圧密状として取り出す浮上濃縮等が用いられている。しかしながら、電力や凝集剤等のランニングコストが大きくなっており、より経済的な濃縮技術が望まれている。そこで、ろ布の吸収能力を利用した濃縮装置が、例えば、この発明の出願人が提案している、実公平４−２７５２２号公報及び特公平１−１２５２６号公報がある。
【０００３】
【発明が解決しようとする課題】
然しながら、従来の重力濃縮装置や遠心濃縮装置は、装置として大きなスペースと大きな動力を必要としていた。また、上記従来の公報のような無端状のろ布を用いるものでは、使用するろ布の寿命が直接ランニングコストに影響しており、ここで使用されるろ布は、織布そのままや、不織布を基材とし、その表面に同様の繊維を熱融着し、付着汚泥の剥離性を改善したものが使用されていた。しかしながら、従来から使用していた織布のままでは、表面に付着した濃縮液の剥離性が悪く、ろ布の早期目詰まりが生じていた。また、使用するろ布が短繊維の不織布では、表面に融着した短繊維層の劣化が激しく、短期に表面層が剥離する欠点があった。しかも、ろ布の駆動に大きな動力が必要な上、ろ布が目詰まりし易く再生が困難であった。この発明は、上述のような課題を解決するために出願人が提案した濃縮装置を改良したものである。、
【０００４】
【課題を解決するための手段】
この発明の要旨は、吸水材で構成した無端状のろ布を濃縮槽に浸漬して走行自在に配設し、そのろ布の一部分を濃縮槽外に導出するとともに、そのろ布の槽外走行部に圧搾装置を設けた濃縮装置において、上記ろ布が長繊維の不織布を基材とし、その表面に長繊維ろ材を熱融着した不織布からなるものである。そして、上該ろ布の圧搾装置が、ろ布を逆Ｗ状に掛け回した三本の支持ロールと、その中間の支持ロールにろ布が反転上昇する部位に押し付けられた加圧ロールとからなり、これらの支持ロールに掛け回わされたろ布が、濃縮槽の槽底部に配設した案内ロールに無端状に掛け回わされて、ろ布を走行自在としたものである。なお、上記走行自在に掛け回したろ布の圧搾装置と案内ロールは、濃縮槽に複数設置してもよいものである。
【０００５】
【発明の実施の形態】
この発明は上記のように構成してあり、この発明の長繊維の不織布の表面に長繊維ろ材を熱融着したろ布を濃縮槽中に浸漬させて走行させると、ろ布の毛細管現象により汚泥中の水分はろ布面に吸水される。濃縮槽の外部に移送されたろ布は、そのろ布面に吸水されたろ液が圧搾装置で脱水され、再び濃縮槽中に浸漬される。濃縮槽中の汚泥濃度が高くなると、ろ布面に多少のＳＳが付着するが、支持ロールでわずかに絞られたろ液が流下する際洗浄され、ＳＳの回収率が高められる。そして、加圧ロールで脱水され、後段の支持ロールでろ布を反転させて脱水されたろ布を濃縮槽に移送させるものである。濃縮装置に使用するろ布は、基材の不織布の表面に融着したろ材層が長繊維の不織布であるので、劣化による剥離がないものであり、吸水性能も長期にわたり高い値が維持されて表面の耐久性も大きいものである。また、ろ布が吸水するに際しても吸水圧が低いので、ろ布が目詰まりすることがなく、連続して汚泥の濃縮が行えるものである。
【０００６】
【実施例】
この発明の実施例を図面に基づき詳述すると、先ず、図１において、符号１は汚泥の濃縮槽であって、この濃縮槽１の液面上には、ろ布２を掛け回した圧搾装置３が配設してあり、この圧搾装置３はろ布２を逆Ｗ状に掛け回した三本の支持ロール４ａ、４ｂ、４ｃと、中間の支持ロール４ｂにろ布２が反転上昇する部位に押し付けられた加圧ロール５とからなっている。これらの支持ロール４ａ、４ｂ、４ｃに掛け回わされたろ布２が、濃縮槽１の槽底部に配設した案内ロール６に無端状に張設されており、加圧ロール５を電動機（図示せず）で駆動して、濃縮槽１に浸漬させたろ布２が、その一部分を濃縮槽１外に導出して循環走行させるようにしてある。圧搾装置３と案内ロール６に張設したろ布２は、図２に示すように、長繊維の不織布を基材２ａとし、その両面に長繊維ろ材２ｂを熱融着した不織布から構成されており、その厚さは、吸水性を保つため、５〜１０ｍｍが好ましい。このろ布２を２．５〜５ｍ／ｍｉｎで走行させることにより、固形物はろ材表面には付着しないで濃縮槽に残留して濃縮が行われる。濃度が高くなれば多少固形物がろ布２に付着しても前段の支持ロール４ａでわずかに絞られたろ液が流下する際洗浄されて濃縮槽１に返送され、ろ液への固形物の混入を防止し、ＳＳの回収率を高めることができる。そして、中間の支持ロール４ｂと加圧ロール５に挟持されて、ろ布２からろ液が分離され、ろ液はろ液トラフ７に回収される。加圧ロール５は支持ロール４ｂのろ布２が反転上昇する部位に押し付けられているので、脱水したろ液が回転するロールの表面を伝って、再びろ布２に吸込まれることがないようにしてある。ろ布２は後段の支持ロール４ｃに掛け回された後、濃縮槽１に浸漬されてろ液を吸水し、濃縮槽１外に導出され、濃縮槽１の汚泥は段々と濃縮される。符号８は原液の供給管であって、下水処理や廃水処理等で発生する無薬注の汚泥を供給ポンプ１０で濃縮槽１に圧送するようにしてある。
【０００７】
そして、上記走行自在に掛け回したろ布２は、図３に示すように、濃縮槽１に設置した複数の圧搾装置３と案内ロール６に連続的に掛け回し、このろ布２が無端状に周回する間に濃縮槽１への浸漬と濃縮槽１外への導出を繰り返しながら汚泥を濃縮させてもよく、汚泥の大容量処理が可能となるものである。そして、走行方向後方の加圧ロール５を駆動装置（図示せず）に連結すればよいものである。圧搾装置３で分離したろ液は複数のろ液トラフ７から集液トラフ９に集められて計量槽１０に排出される。計量槽１０には液面計１１が設けてあり、分離されたろ液量が検知できるようにしてある。この液面計１１の検知信号で、集液トラフ９と計量槽１０との間に設けた開閉弁１２と、計量槽１０の槽底に設けた排液用の開閉弁１３を開閉して、所定量となったろ液を排出するようにしてある。また、濃縮槽１にも液面計１４が設けてあり、濃縮された汚泥の液面が検知できるようにしてあり、計測された濃縮汚泥を濃縮槽１の底部に設けた開閉弁１５から排出するようにしてある。
【０００８】
ろ材の吸水性の比較テストを行った。先ず、この発明のろ布である長繊維の不織布を基材としてその表面に長繊維を熱融着したろ材と、フェルト状ろ材、及び表面加工スポンジの三種類のろ材を１００ｍｍ□の吸水ろ材サンプルとし、Ａ処理場の活性余剰汚泥に浸漬して、ろ材単位容積当たりの吸水量を比較した。その結果、表１のように、この発明のろ布が最も吸水量が多く、吸水速度も速かった。
【０００９】
【表１】

【００１０】
各ろ材をこの発明の図１の濃縮装置に装着し、ろ材走行速度２．５ｍ／ｍｉｎ、濃縮槽内汚泥濃度を約１％にして、能力の安定性並びに耐久性について試験した。その結果は表２及び表３のとおりであり、能力安定性とろ材の耐久性に優れていたのはこの発明のろ材であった。
【００１１】
【表２】

【００１２】
【表３】

【００１３】
Ａ処理場とＢ処理場の活性余剰汚泥について、無薬注にて濃縮試験を実施した。累積ろ液量の経時変化は、表４のように、ほぼ直線的に増加することが分かった。即ち、表５及び表６のように、濃縮倍率が直線的に増加しているにも関わらず、ろ過速度はほとんど低下せず、ほぼ一定に推移している。
【００１４】
【表４】

【００１５】
【表５】

【００１６】
【表６】

【００１７】
また、ろ布走行速度を２．５ｍ／ｍｉｎから５ｍ／ｍｉｎに早くした場合、ほぼ走行速度に比例して、ろ過速度が上昇している。これは、汚泥の固液分離過程でろ材表面にろ過抵抗となるケーキが形成しないことに起因するものと考えられる。更に、圧搾装置で脱水する際、ろ材表面並びに内部のＳＳがろ液と共に排出され、目詰まり解消となっていることも安定したろ過が行える要因と考えられる。
【００１８】
【発明の効果】
以上のように、この発明に係る汚泥の濃縮装置は、濃縮槽とロールのシンプルな構成に吸水性のあるろ材を張設して走行させるものであり、ろ布の吸水圧が低いので目詰まりすることがなく、汚泥も無薬注であり、ロールを走行させるエネルギーのみで短時間で高濃度汚泥が得られるものである。即ち、従来使用している織布のろ布では、表面に付着した濃縮液の剥離性が悪く、また、ろ布が短繊維の不織布では、表面に融着した短繊維層の劣化が激しく、短期間に表面層が剥離する欠点があった。しかも、これらの従来のろ布では、ろ布の駆動に大きな動力が必要な上、ろ布が目詰まりし易く再生が困難であったものであるが、この発明に係るろ布にあっては、長繊維の不織布を基材として、その表面に長繊維ろ材を熱融着したろ材であるので、吸水性能も長期にわたり高い値を維持でき、表面に融着した長繊維の剥離もなく、表面層の耐久性が大きいものである。そして、この発明に係る圧搾装置は、前段の支持ロールでわずかに絞られたろ液がろ布に付着した固形物をあらい流し、濃縮槽での固形物の回収率を高め、同時にろ布の目詰まりを防止する。そして、支持ロールに押し付けた加圧ロールが、ろ布が反転上昇する部位に設けてあるので、ろ布から分離されたろ液が再びろ布に吸引されることがないものである。
【図面の簡単な説明】
【図１】この発明に係る濃縮装置の摸式縦断側面図である。
【図２】この発明の濃縮装置に使用するろ布の一部の斜視図である。
【図３】この発明に係る濃縮装置の他の実施例の一部縦断斜視図である。
【符号の説明】
１濃縮槽
１ａ流路板
２ろ布
２ａ基材
２ｂ長繊維ろ材
３圧搾装置
４ａ支持ロール
４ｂ支持ロール
４ｃ支持ロール
５加圧ロール
６案内ロール[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for concentrating sludge generated at a sewage treatment plant, a wastewater treatment plant or the like, and in particular, a water-absorbing endless filter cloth disposed so as to run freely is immersed in the stock solution, and the absorbed filter cloth is absorbed. The present invention relates to an apparatus for concentrating a stock solution by dehydration outside a concentration tank.
[0002]
[Prior art]
The sludge generated in sewage treatment has deteriorated concentration due to an increase in organic matter, and it is difficult to obtain a predetermined concentration. For this reason, gravity concentration that separates the supernatant liquid by precipitating heavy sludge, centrifugal concentration that separates heavy sludge and liquid components using centrifugal force, or pressing up the sludge using compressed air for consolidation Floating concentration etc. taken out as a shape are used. However, running costs such as electric power and flocculant are increasing, and more economical concentration techniques are desired. Therefore, there are, for example, Japanese Utility Model Publication Nos. 4-27522 and 1-1526 proposed by the applicant of the present invention as a concentrator utilizing the absorption capacity of the filter cloth.
[0003]
[Problems to be solved by the invention]
However, conventional gravity concentrators and centrifugal concentrators require a large space and a large power as a device. In addition, in the case of using an endless filter cloth as in the above-mentioned conventional publication, the life of the filter cloth used directly affects the running cost, and the filter cloth used here can be a woven cloth or a non-woven cloth. The base fiber was used, and the same fiber was thermally fused on the surface to improve the peelability of the attached sludge. However, with a woven fabric that has been used in the past, the peelability of the concentrated liquid adhering to the surface was poor, and the filter fabric was prematurely clogged. In addition, when the filter cloth used is a short fiber non-woven fabric, the short fiber layer fused to the surface is severely deteriorated and the surface layer peels off in a short time. Moreover, a large amount of power is required to drive the filter cloth, and the filter cloth is easily clogged and difficult to regenerate. The present invention is an improvement of the concentrator proposed by the applicant in order to solve the above-described problems. ,
[0004]
[Means for Solving the Problems]
The gist of the present invention is that an endless filter cloth made of a water-absorbing material is immersed in a concentrating tank and disposed so as to be able to run, and a part of the filter cloth is led out of the concentrating tank, and the filter cloth is outside the tank. In the concentrating device provided with a squeezing device in the traveling part, the filter cloth is made of a nonwoven fabric in which a nonwoven fabric of long fibers is used as a base material, and a long fiber filter medium is thermally fused on the surface thereof. The upper filter cloth pressing device is composed of three support rolls in which the filter cloth is wound in an inverted W shape, and a pressure roll pressed against a portion where the filter cloth is inverted and raised by the intermediate support roll. Thus, the filter cloth hung around these support rolls is endlessly hung on a guide roll disposed at the bottom of the concentration tank, so that the filter cloth can run freely. Note that a plurality of filter cloth squeezing devices and guide rolls that are hung around may be installed in the concentration tank.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is configured as described above. When a filter cloth in which a long-fiber filter medium is heat-sealed on the surface of the non-woven fabric of the present invention is immersed in a concentrating tank and run, the capillary action of the filter cloth causes Water in the sludge is absorbed by the filter cloth surface. As for the filter cloth transferred to the outside of the concentration tank, the filtrate absorbed in the filter cloth surface is dehydrated by the squeezing device and is immersed again in the concentration tank. When the sludge concentration in the concentration tank increases, some SS adheres to the filter cloth surface, but when the filtrate slightly squeezed by the support roll flows down, the SS is recovered. And it spin-dry | dehydrates with a pressure roll, reverses a filter cloth with a support roller of a back | latter stage, and transfers the dehydrated filter cloth to a concentration tank. The filter cloth used in the concentrator is a non-woven fabric with a long-fiber filter medium layer fused to the surface of the nonwoven fabric of the base material, so there is no peeling due to deterioration, and the water absorption performance is maintained at a high value for a long time. The durability of the surface is also great. Further, since the water absorption pressure is low when the filter cloth absorbs water, the filter cloth is not clogged and the sludge can be continuously concentrated.
[0006]
【Example】
An embodiment of the present invention will be described in detail with reference to the drawings. First, in FIG. 1, reference numeral 1 denotes a sludge concentration tank, and a pressing device in which a filter cloth 2 is wound around the liquid surface of the concentration tank 1. 3 is arranged, and this pressing device 3 is provided at three support rolls 4a, 4b, and 4c obtained by wrapping the filter cloth 2 in an inverted W shape, and at a portion where the filter cloth 2 is inverted and raised on the intermediate support roll 4b. It consists of a pressure roll 5 pressed. The filter cloth 2 hung around these support rolls 4a, 4b and 4c is stretched endlessly on a guide roll 6 disposed at the bottom of the concentration tank 1, and the pressure roll 5 is connected to an electric motor (see FIG. The filter cloth 2 that is driven in the concentrating tank 1 is driven out of the concentrating tank 1 and is circulated and driven out of the concentrating tank 1. As shown in FIG. 2, the filter cloth 2 stretched between the pressing device 3 and the guide roll 6 is composed of a non-woven fabric in which a non-woven fabric of long fibers is used as a base material 2a and the long-fiber filter media 2b is heat-sealed on both sides thereof. In order to maintain water absorption, the thickness is preferably 5 to 10 mm. By running the filter cloth 2 at 2.5 to 5 m / min, the solid matter does not adhere to the surface of the filter medium but remains in the concentration tank and is concentrated. If the concentration is increased, even if some solid matter adheres to the filter cloth 2, it is washed and returned to the concentration tank 1 when the filtrate slightly squeezed by the support roll 4a in the previous stage flows down, and the solid matter to the filtrate is returned to the filtrate. Mixing can be prevented and the recovery rate of SS can be increased. And it is pinched by the intermediate | middle support roll 4b and the pressurization roll 5, a filtrate is isolate | separated from the filter cloth 2, and a filtrate is collect | recovered by the filtrate trough 7. FIG. Since the pressure roll 5 is pressed against the portion of the support roll 4b where the filter cloth 2 is inverted and lifted, the dehydrated filtrate is not sucked into the filter cloth 2 again along the surface of the rotating roll. It is. The filter cloth 2 is wound around the support roll 4c in the subsequent stage, and is immersed in the concentration tank 1 to absorb the filtrate and is led out of the concentration tank 1. The sludge in the concentration tank 1 is gradually concentrated. Reference numeral 8 denotes a stock solution supply pipe, which is configured to pump non-chemically injected sludge generated in sewage treatment, wastewater treatment, or the like to the concentration tank 1 by a supply pump 10.
[0007]
And as shown in FIG. 3, the said filter cloth 2 hung around so that it can run freely hung around the several pressing apparatus 3 and the guide roll 6 which were installed in the concentration tank 1, and this filter cloth 2 is endless. The sludge may be concentrated while being repeatedly immersed in the concentration tank 1 and led out of the concentration tank 1 during the circulation, so that a large volume of sludge can be treated. And what is necessary is just to connect the pressurization roll 5 of a running direction back to a drive device (not shown). The filtrate separated by the squeezing device 3 is collected from a plurality of filtrate troughs 7 into a collection trough 9 and discharged to a measuring tank 10. The measuring tank 10 is provided with a liquid level gauge 11 so that the separated filtrate amount can be detected. With the detection signal of the liquid level gauge 11, the on-off valve 12 provided between the liquid collection trough 9 and the measuring tank 10 and the drain on-off valve 13 provided on the bottom of the measuring tank 10 are opened and closed, The filtrate that has reached a predetermined amount is discharged. Further, a liquid level gauge 14 is also provided in the concentration tank 1 so that the liquid level of the concentrated sludge can be detected, and the measured concentrated sludge is discharged from the on-off valve 15 provided at the bottom of the concentration tank 1. I have to do it.
[0008]
A comparative test of the water absorption of the filter medium was conducted. First, a 100 mm-square water-absorbing filter medium sample includes three types of filter media: a filter medium in which long fibers are non-woven fabric, which is the filter cloth of the present invention, and a long fiber is thermally fused to the surface, a felt-shaped filter medium, and a surface-treated sponge. Then, the amount of water absorption per unit volume of the filter medium was compared by immersing in the activated surplus sludge of the A treatment plant. As a result, as shown in Table 1, the filter cloth of the present invention had the largest water absorption amount and the high water absorption rate.
[0009]
[Table 1]

[0010]
Each filter medium was mounted on the concentrator of FIG. 1 of the present invention, and the stability of the capacity and the durability were tested with a filter medium traveling speed of 2.5 m / min and a sludge concentration in the concentration tank of about 1%. The results are as shown in Table 2 and Table 3. The filter medium of the present invention was excellent in capacity stability and filter medium durability.
[0011]
[Table 2]

[0012]
[Table 3]

[0013]
About the activated surplus sludge of A processing plant and B processing plant, the concentration test was carried out by non-chemical injection. As shown in Table 4, it was found that the change with time of the cumulative filtrate amount increased almost linearly. That is, as shown in Tables 5 and 6, the filtration rate hardly decreased and remained almost constant, although the concentration rate increased linearly.
[0014]
[Table 4]

[0015]
[Table 5]

[0016]
[Table 6]

[0017]
Further, when the filter cloth traveling speed is increased from 2.5 m / min to 5 m / min, the filtration speed increases almost in proportion to the traveling speed. This is considered to be caused by the fact that a cake that becomes filtration resistance is not formed on the surface of the filter medium in the solid-liquid separation process of sludge. Furthermore, when dewatering with a squeezing device, the fact that the surface of the filter medium and the internal SS are discharged together with the filtrate and clogging is eliminated is also considered to be a factor that enables stable filtration.
[0018]
【The invention's effect】
As described above, the sludge concentration apparatus according to the present invention is configured to run with a filter medium having water absorption in a simple configuration of a concentration tank and a roll, and is clogged because the water absorption pressure of the filter cloth is low. The sludge is also non-chemically poured, and high-concentration sludge can be obtained in a short time using only the energy for running the roll. That is, in the filter cloth of the woven cloth used conventionally, the peelability of the concentrated liquid adhering to the surface is bad, and in the non-woven cloth of the short fiber filter cloth, the deterioration of the short fiber layer fused to the surface is severe, There was a drawback that the surface layer peeled off in a short time. Moreover, these conventional filter cloths require a large amount of power to drive the filter cloth, and the filter cloth is easily clogged and difficult to regenerate. The filter medium is made of a long-fiber non-woven fabric as a base material, and a long-fiber filter medium is heat-sealed on the surface thereof. The layer is highly durable. The squeezing device according to the present invention allows the filtrate slightly squeezed by the support roll in the previous stage to flow away the solid matter adhering to the filter cloth, increasing the recovery rate of the solid substance in the concentration tank, and at the same time Prevent clogging. And since the pressurization roll pressed against the support roll is provided in the site | part where a filter cloth inverts and raises, the filtrate isolate | separated from the filter cloth is not attracted | sucked by the filter cloth again.
[Brief description of the drawings]
FIG. 1 is a vertical vertical side view of a concentrator according to the present invention.
FIG. 2 is a perspective view of a part of a filter cloth used in the concentration apparatus of the present invention.
FIG. 3 is a partially longitudinal perspective view of another embodiment of the concentrating device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Concentration tank 1a Channel plate 2 Filter cloth 2a Base material 2b Long fiber filter medium 3 Squeezing device 4a Support roll 4b Support roll 4c Support roll 5 Pressure roll 6 Guide roll

Claims

An endless filter cloth (2) made of a water-absorbing material is immersed in the concentration tank (1) and arranged to run freely, and a part of the filter cloth (2) is led out of the concentration tank (1), In the concentration device in which the pressing device (3) is provided in the traveling part outside the tank of the filter cloth (2), the filter cloth (2) uses a non-woven fabric of long fibers as a base material (2a), and a long fiber filter medium ( A sludge concentrating device comprising a nonwoven fabric heat-sealed 2b).

The filter device (3) of the upper filter cloth (2) has three support rolls (4a, 4b, 4c) in which the filter cloth (2) is wound in an inverted W shape, and an intermediate support roll (4b). It consists of a pressure roll (5) pressed against the part where the filter cloth (2) is inverted and raised, and the filter cloth (2) wound around these support rolls (4a, 4b, 4c) The sludge concentrating device according to claim 1, wherein the filter cloth (2) is made to run freely by being wound endlessly on a guide roll (6) disposed on the tank bottom of (1).

The sludge according to claim 1 or 2, characterized in that a plurality of pressing devices (3) and guide rolls (6) of the filter cloth (2) hanged around are installed in the concentration tank (1). Concentration device.