CA1163571A - Method and apparatus for dewatering sludge - Google Patents
Method and apparatus for dewatering sludgeInfo
- Publication number
- CA1163571A CA1163571A CA000368798A CA368798A CA1163571A CA 1163571 A CA1163571 A CA 1163571A CA 000368798 A CA000368798 A CA 000368798A CA 368798 A CA368798 A CA 368798A CA 1163571 A CA1163571 A CA 1163571A
- Authority
- CA
- Canada
- Prior art keywords
- sludge
- conveying
- particles
- output end
- ramp
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/04—Filters with filtering elements which move during the filtering operation with filtering bands or the like supported on cylinders which are impervious for filtering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/44—Regenerating the filter material in the filter
- B01D33/46—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element
- B01D33/466—Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element scrapers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
- B01D33/74—Filters with filtering elements which move during the filtering operation having feed or discharge devices for discharging filtrate
- B01D33/742—Filters with filtering elements which move during the filtering operation having feed or discharge devices for discharging filtrate containing fixed liquid displacement elements or cores
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Treatment Of Sludge (AREA)
- Filtration Of Liquid (AREA)
- Sink And Installation For Waste Water (AREA)
- Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
Abstract
ABSTRACT
A METHOD AND APPARATUS FOR DEWATERING SLUDGE
A system for dewatering sludge where the sludge is placed onto a moving foraminous conveying surface (10) so that water can drain freely from the sludge through the surface (10) to be deposited at the output end thereof into a collecting trough (20), there being at the output end of the conveying run, a ramp (25) which? positioned between fixed side plates (27) causes a restriction and build-up of sludge particles on the surface of the ramp thus to increase the potential energy of the particles, and, by virtue of a backwards rolling action and compaction of the particles provide increased drainage of liquids from the sludge.
A METHOD AND APPARATUS FOR DEWATERING SLUDGE
A system for dewatering sludge where the sludge is placed onto a moving foraminous conveying surface (10) so that water can drain freely from the sludge through the surface (10) to be deposited at the output end thereof into a collecting trough (20), there being at the output end of the conveying run, a ramp (25) which? positioned between fixed side plates (27) causes a restriction and build-up of sludge particles on the surface of the ramp thus to increase the potential energy of the particles, and, by virtue of a backwards rolling action and compaction of the particles provide increased drainage of liquids from the sludge.
Description
`~ 6~5~ 1 ~ F/1675 A MET~IOD AND APPARAI'US FOR DEl~ATERING SI~UDGE
"
THIS INVENTIO~ relates to a method and ; apparatus for dewatering sludge particularly, though `; by no means exclusively, activated sludge.
.
For many years activated sludge has been thickened by passage through a settling tank such that the residence time in the tank is of the order o-f 24 hours. This technique, besides requ~iTing much time and large equipment has the disadvantage that :
the thickened sludge will have a solid concentration of only 1.5 to 2 per cent by weight.
~, . .
With a vie~ to obtaining higher levels of sollds in the concentrated sludge various techniques have been developed utilising sophisticated equipment such as flotation apparatus where suspended solids , contained within the sludge are carried to the surface by small bubbles of gas produced by electrolytic action. Such flotation apparatus is effective in removing water from the sludge so that the concentrated sludge will haYe 5 per ~nt by weight of solids or thereabouts. This technique has a number of disadvantages in that the equipment used is costly to purchase and maintain and that the processing costs '''
"
THIS INVENTIO~ relates to a method and ; apparatus for dewatering sludge particularly, though `; by no means exclusively, activated sludge.
.
For many years activated sludge has been thickened by passage through a settling tank such that the residence time in the tank is of the order o-f 24 hours. This technique, besides requ~iTing much time and large equipment has the disadvantage that :
the thickened sludge will have a solid concentration of only 1.5 to 2 per cent by weight.
~, . .
With a vie~ to obtaining higher levels of sollds in the concentrated sludge various techniques have been developed utilising sophisticated equipment such as flotation apparatus where suspended solids , contained within the sludge are carried to the surface by small bubbles of gas produced by electrolytic action. Such flotation apparatus is effective in removing water from the sludge so that the concentrated sludge will haYe 5 per ~nt by weight of solids or thereabouts. This technique has a number of disadvantages in that the equipment used is costly to purchase and maintain and that the processing costs '''
2 --are high.
The applicant has conducted an extensive research programme with a view to finding a method of thickening sludge to have a concentration of the order of 5 per cent by weight of solids or more, with simple equipment and in an e~conomic manner.
According to the present invention, there is provided a method of dewatering sludge, comprising the steps of placing the sludge onto a foraminous conveying surface moving continuously in one direction, to permit liquid to drain freely therethrough during conveyance, and removing drainèd solids from the conveying s~rface at the output end of the conveying run, characterized in that forwards movement of the sludge is restricted in the output end region of the conveying run where the sludge is constrained to rise up a ramp surface extending upwardly from the conveying surface thus to create a backwards rolling action for particles of sludge on the ramp surface, which in turn imparts to said particles a shearing action thus to release trapped liquids from between the particles and to allow increased compaction thereof.
The invention also extends to apparatus for carrying out the aforesaid method.
The invention will become further apparent from the following description of the method carried out using one form of apparatus in accordance with the invention. Such apparatus is illustrated - - _ ~. ~
~ ~ 3 63571 ~ 3 - EF/1675 by way of example only, in the accompanying drawings in which:-Fig~ 1 is a diagrammatic vertical sectional vie~ of the apparatus in use;
., Fig. 2 is an enlarged view of part of the apparatus of Fig. 1 sho~ing greater detail;
and Fig. 3 is a plan view of the part of the apparatus shown in Fig. 2.
.
Referring now to the drawings the apparatus generally comprises a mesh conveying belt 10 driven by or wrapped around a plurality of support rollers - 11, 12 and 13. Sludge to be processed is placed onto the moving belt 10 via a ramp 14 fed rom a tank 15.
Positioned below the belt 10 are a pair of ~ ~ 15 guide plates 16 and 17 adapted to collect water -~ passing through the belt 10 and to direct the water into a coIlecting trough 18 for disposal. It will be seen that the water passing from the guide plates 16 and 17 to the trough 18 is caused to pass through the belt 10 in one of its re~urn runs between support rollers 12 and 11, thus washing from the conveying surface of the belt any materials remaining thereon.
, J ~ 63~1 - 4 - ~F/1675 A collecting trough 20 is provided below the downstream end of the conveying run of the belt for collection of dewatered solids. Conveniently, a screw conveyor 21, or similar device is used for removing the solids from the trough~
In accordance with the invention, a ramp surface generalIy indicated at 25 is provided adjacent the downstream end of the conveying run of ~ ~ the belt 10~ and a portion 26 (see Fig. 2) of the ; 10 ramp surface is positioned to serve as a scraper blade to ensure cleaning of the belt. Fixed side plates 27 are provided to constrain the material as it accumulates on the ramp surface 25.
, . .
~hen the apparatus is operating the sludge is fed continuously from the tank 15 onto the belt 10-and is carried along the latter whilst liquids are permitted to drain freely through the belt 10 for collection. At ~he downstream end of the conveying run the dewatered sludge must rise up the ramp surface 25 before passing over the upper end of the latter and into the trough 20 for collection.
The effect of the ramp surface is to cause the particles of material in the sludge to build up and fall backwards onto the belt as indicated by the arrow 30. This causes relative movement betw-een the ~ ~ 63~7~
solid particles thereby imparting a shearing action to release trapped liquids and hence allow greater compaction. Thus, also, pressure is exerted on the lowermost particlas by the weight of particles on the ramp, and by the continuous pressure exerted by oncoming material on the belt. These ~actors permit further considerable drainage of liquid from the sludge so that the final sludge has a solids concentration of as much as 6.5 per cent by weight, or more.
'::
It has been found by experiment that,the angle of inclination of the ramp surface determines the effectiveness of the dewatering action in this région. Generally, the solids concentration is I5 proportional to the angle of the ramp.
Whilst the ramp surface has been shown as being disposed at the output end of the conveying run, it is conceivable that it can be placed part-way along the latter, and that there may be more than one such ramp surface provided along the conveying run.
.
Referring now to Fig. 3 it will be seen that a further restriction to free forwards movement ~, of the sludge can be provided by V-shaped member ~1 , .
~ ~ 6357~
positioned on the ramp surface to cause lateral ~ constriction of the sludge particles as they rise up : the ramp. In some instances this may provide an improvement, particularly in cases where free drainage of liquid from the sludge through the belt is not readily achieved during conveyance.
The applicant has conducted an extensive research programme with a view to finding a method of thickening sludge to have a concentration of the order of 5 per cent by weight of solids or more, with simple equipment and in an e~conomic manner.
According to the present invention, there is provided a method of dewatering sludge, comprising the steps of placing the sludge onto a foraminous conveying surface moving continuously in one direction, to permit liquid to drain freely therethrough during conveyance, and removing drainèd solids from the conveying s~rface at the output end of the conveying run, characterized in that forwards movement of the sludge is restricted in the output end region of the conveying run where the sludge is constrained to rise up a ramp surface extending upwardly from the conveying surface thus to create a backwards rolling action for particles of sludge on the ramp surface, which in turn imparts to said particles a shearing action thus to release trapped liquids from between the particles and to allow increased compaction thereof.
The invention also extends to apparatus for carrying out the aforesaid method.
The invention will become further apparent from the following description of the method carried out using one form of apparatus in accordance with the invention. Such apparatus is illustrated - - _ ~. ~
~ ~ 3 63571 ~ 3 - EF/1675 by way of example only, in the accompanying drawings in which:-Fig~ 1 is a diagrammatic vertical sectional vie~ of the apparatus in use;
., Fig. 2 is an enlarged view of part of the apparatus of Fig. 1 sho~ing greater detail;
and Fig. 3 is a plan view of the part of the apparatus shown in Fig. 2.
.
Referring now to the drawings the apparatus generally comprises a mesh conveying belt 10 driven by or wrapped around a plurality of support rollers - 11, 12 and 13. Sludge to be processed is placed onto the moving belt 10 via a ramp 14 fed rom a tank 15.
Positioned below the belt 10 are a pair of ~ ~ 15 guide plates 16 and 17 adapted to collect water -~ passing through the belt 10 and to direct the water into a coIlecting trough 18 for disposal. It will be seen that the water passing from the guide plates 16 and 17 to the trough 18 is caused to pass through the belt 10 in one of its re~urn runs between support rollers 12 and 11, thus washing from the conveying surface of the belt any materials remaining thereon.
, J ~ 63~1 - 4 - ~F/1675 A collecting trough 20 is provided below the downstream end of the conveying run of the belt for collection of dewatered solids. Conveniently, a screw conveyor 21, or similar device is used for removing the solids from the trough~
In accordance with the invention, a ramp surface generalIy indicated at 25 is provided adjacent the downstream end of the conveying run of ~ ~ the belt 10~ and a portion 26 (see Fig. 2) of the ; 10 ramp surface is positioned to serve as a scraper blade to ensure cleaning of the belt. Fixed side plates 27 are provided to constrain the material as it accumulates on the ramp surface 25.
, . .
~hen the apparatus is operating the sludge is fed continuously from the tank 15 onto the belt 10-and is carried along the latter whilst liquids are permitted to drain freely through the belt 10 for collection. At ~he downstream end of the conveying run the dewatered sludge must rise up the ramp surface 25 before passing over the upper end of the latter and into the trough 20 for collection.
The effect of the ramp surface is to cause the particles of material in the sludge to build up and fall backwards onto the belt as indicated by the arrow 30. This causes relative movement betw-een the ~ ~ 63~7~
solid particles thereby imparting a shearing action to release trapped liquids and hence allow greater compaction. Thus, also, pressure is exerted on the lowermost particlas by the weight of particles on the ramp, and by the continuous pressure exerted by oncoming material on the belt. These ~actors permit further considerable drainage of liquid from the sludge so that the final sludge has a solids concentration of as much as 6.5 per cent by weight, or more.
'::
It has been found by experiment that,the angle of inclination of the ramp surface determines the effectiveness of the dewatering action in this région. Generally, the solids concentration is I5 proportional to the angle of the ramp.
Whilst the ramp surface has been shown as being disposed at the output end of the conveying run, it is conceivable that it can be placed part-way along the latter, and that there may be more than one such ramp surface provided along the conveying run.
.
Referring now to Fig. 3 it will be seen that a further restriction to free forwards movement ~, of the sludge can be provided by V-shaped member ~1 , .
~ ~ 6357~
positioned on the ramp surface to cause lateral ~ constriction of the sludge particles as they rise up : the ramp. In some instances this may provide an improvement, particularly in cases where free drainage of liquid from the sludge through the belt is not readily achieved during conveyance.
Claims (10)
1. A method of dewatering sludge,comprising the steps of placing the sludge onto a foraminous conveying surface moving continuously in one direction, to permit liquid to drain freely therethrough during conveyance, and removing drained solids from the conveying surface at the output end of the conveying run, characterised in that forwards movement of the sludge is restricted in the output end region of the conveying run where the sludge is constrained to rise up a ramp surface extending upwardly from the conveying surface thus to create a backwards rolling action for particles of sludge on the ramp surface, which in turn imparts to said particles a shearing action thus to release trapped liquids from between the particles and to allow increased compaction thereof.
2. A method according to Claim 1, wherein said ramp surface is located immediately prior to the output end of the conveying run.
3. A method according to Claim 1, wherein, in said output end region, movement of sludge particles in a direction transverse to that of the conveying run is constrained by the provision of side plates.
4. A method according to Claim 1, wherein the sludge particles are laterally constrained as they ascend the ramp surface by means disposed part way across the latter to divide the sludge stream.
5. A method according to Claim 1, wherein said sludge is dewatered to a solids concentration in excess of 6 per cent by weight.
6. Apparatus for dewatering sludge, comprising a foraminous conveying belt moving continuously in one direction, means for placing sludge onto said belt at the input end of a conveying run, so that liquid drains through the belt, means for collecting drained solids at the output end of said conveying run, and a ramp surface extending upwardly from the conveying run and disposed in the output end region thereof whereby the sludge is constrained to rise up the ramp surface and thus create a backwards rolling action for particles of sludge on the ramp surface.
7. Apparatus according to Claim 6, wherein said ramp surface is located immediately prior to the output end of the conveying run, and side plates are arranged so as to restrict lateral movement of solids particles with respect to the direction of conveyance.
8. Apparatus according to Claim 6, wherein a lower portion of said ramp surface is disposed in close proximity with the conveying surface of said belt to serve as a scraper blade thus cleaning said belt surface.
9. Apparatus according to Claim 7, including an upstanding fixed member disposed on the ramp so as to divide the stream of sludge ascending the ramp thus to impart lateral constriction to the sludge particles.
10. Apparatus according to Claim 6, including guide plates below the conveying run to direct water drained therethrough onto the return run of the belt thus to pass through the latter to wash any residual solids from the conveying surface thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8003495A GB2068761B (en) | 1980-02-01 | 1980-02-01 | Method and apparatus for dewatering sludge |
| GB8003495 | 1980-02-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1163571A true CA1163571A (en) | 1984-03-13 |
Family
ID=10511066
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000368798A Expired CA1163571A (en) | 1980-02-01 | 1981-01-19 | Method and apparatus for dewatering sludge |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS56124409A (en) |
| AU (1) | AU539433B2 (en) |
| CA (1) | CA1163571A (en) |
| DE (1) | DE3101105A1 (en) |
| FR (1) | FR2475031B1 (en) |
| GB (1) | GB2068761B (en) |
| HK (1) | HK77087A (en) |
| IT (1) | IT1135235B (en) |
| NL (1) | NL188327C (en) |
| NO (1) | NO152126C (en) |
| SE (2) | SE442592B (en) |
| SG (1) | SG25487G (en) |
| ZA (1) | ZA81329B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4731188A (en) * | 1986-04-03 | 1988-03-15 | Ashbrook-Simon-Hartley | Adjustable ramp for dewatering device |
| GB8909463D0 (en) * | 1989-04-26 | 1989-06-14 | Hartley Simon Ltd | Apparatus for dewatering sludge |
| GB2232611B (en) * | 1989-06-02 | 1992-10-14 | D & C Ltd | Horizontal belt vacuum filtration apparatus |
| DE59000338D1 (en) * | 1989-06-30 | 1992-11-12 | Hoppe & Partner | METHOD AND DEVICE FOR PRE-THICKENING SLUDGE. |
| WO2003068695A1 (en) * | 2002-02-15 | 2003-08-21 | Kubota Corporation | Gravity type thickener, gravity type thickening method, coagulant adding device, and coagulant adding method |
| CN116537744B (en) * | 2023-07-07 | 2023-09-08 | 山东省路桥集团有限公司 | Drilling machine blowdown mechanism for road construction |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB754168A (en) * | 1953-06-25 | 1956-08-01 | Lukens Steel Co | Rotary table filter |
| GB909512A (en) * | 1960-03-22 | 1962-10-31 | Arthur Andrew Holland | Endless belt filter |
| SE365122B (en) * | 1972-04-13 | 1974-03-18 | Nordstjernan Rederi Ab | |
| NL176054C (en) * | 1974-02-27 | 1985-02-18 | Bellmer Geb Kg Maschf | FILTER EQUIPMENT. |
| GB1602677A (en) * | 1978-05-25 | 1981-11-11 | Hartley Simon Ltd | Sludge thickening |
-
1980
- 1980-02-01 GB GB8003495A patent/GB2068761B/en not_active Expired
-
1981
- 1981-01-15 DE DE19813101105 patent/DE3101105A1/en active Granted
- 1981-01-19 CA CA000368798A patent/CA1163571A/en not_active Expired
- 1981-01-19 ZA ZA00810329A patent/ZA81329B/en unknown
- 1981-01-26 NL NLAANVRAGE8100357,A patent/NL188327C/en not_active IP Right Cessation
- 1981-01-29 AU AU66736/81A patent/AU539433B2/en not_active Expired
- 1981-01-30 IT IT19418/81A patent/IT1135235B/en active
- 1981-01-30 SE SE8100710A patent/SE442592B/en not_active IP Right Cessation
- 1981-01-30 JP JP1372581A patent/JPS56124409A/en active Pending
- 1981-01-30 FR FR8101852A patent/FR2475031B1/en not_active Expired
- 1981-01-30 NO NO810336A patent/NO152126C/en not_active IP Right Cessation
- 1981-01-30 SE SE8100710D patent/SE8100710L/en not_active Application Discontinuation
-
1987
- 1987-03-12 SG SG254/87A patent/SG25487G/en unknown
- 1987-10-15 HK HK770/87A patent/HK77087A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| NO152126B (en) | 1985-04-29 |
| AU539433B2 (en) | 1984-09-27 |
| FR2475031A1 (en) | 1981-08-07 |
| NO810336L (en) | 1981-08-03 |
| NL188327C (en) | 1992-06-01 |
| ZA81329B (en) | 1982-02-24 |
| IT8119418A0 (en) | 1981-01-30 |
| GB2068761A (en) | 1981-08-19 |
| AU6673681A (en) | 1981-08-06 |
| SE8100710L (en) | 1981-08-02 |
| HK77087A (en) | 1987-10-23 |
| NO152126C (en) | 1985-08-28 |
| JPS56124409A (en) | 1981-09-30 |
| SE442592B (en) | 1986-01-20 |
| DE3101105A1 (en) | 1981-11-19 |
| SG25487G (en) | 1987-09-18 |
| FR2475031B1 (en) | 1986-05-09 |
| IT1135235B (en) | 1986-08-20 |
| NL188327B (en) | 1992-01-02 |
| GB2068761B (en) | 1984-04-26 |
| DE3101105C2 (en) | 1987-07-23 |
| NL8100357A (en) | 1981-09-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |