CA1122537A - Process for thickening sludge - Google Patents
Process for thickening sludgeInfo
- Publication number
- CA1122537A CA1122537A CA314,450A CA314450A CA1122537A CA 1122537 A CA1122537 A CA 1122537A CA 314450 A CA314450 A CA 314450A CA 1122537 A CA1122537 A CA 1122537A
- Authority
- CA
- Canada
- Prior art keywords
- sludge
- filter
- concentrator
- approximately
- clean water
- 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
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D21/00—Separation of suspended solid particles from liquids by sedimentation
- B01D21/0012—Settling tanks making use of filters, e.g. by floating layers of particulate material
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Treatment Of Sludge (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides a process for concentrating a sludge from the municipal or industrial sector which comprises feeding the sludge into a concentrator having disposed therein one or several filters; each filter having porous walls such that said sludge surrounds said filter and clean water filters from the outside through said walls into a filter space, the cleaned water being drawn off from the filter space and thickened sludge being drawn off from the bottom of the concentrator.
The invention provides a process for concentrating a sludge from the municipal or industrial sector which comprises feeding the sludge into a concentrator having disposed therein one or several filters; each filter having porous walls such that said sludge surrounds said filter and clean water filters from the outside through said walls into a filter space, the cleaned water being drawn off from the filter space and thickened sludge being drawn off from the bottom of the concentrator.
Description
~.~ZZ537 The present invention relates to a process Eor con-tinuously or discontinuously concent-ating sludge, which s~udgeis preferably flocculated and an apparatus for use in the process.
Heretofore, it has been customary to concentrate dilute sludge, obtained in the treatment of water, in concen-trators by using large sludge-storage tanks, in which the physically bound water is released and removed while stirring.
The release of the water can be slightly accelerated by the addition of calcium oxide or iron sulphate. With many types of sludge usually not more than 30~6 of turbid water is drawn off by this method. Thus, for example, for concentrating a biological excess sludge containing approximately 0.6~ of dry solids in a 100-cu m concentrator without the use of a mechanical agitator but with the addition of lime as a conditioning agent and odor~reducing agent from 17 to 36 hours were required to draw off approximately 20% of turbid water from the sludge.
The expenditure of work required for the portionwise addition of the lime and mixing with the sludge was very high. The resulting degree of concentration of the sludge and of separating the water is relatively low.
~ ccording to another method water removal is so carried out by adding flocculating agents which consist of cation-active, D anion-active or non- nionil~substances or mixtures thereof depen-ding on the condition of the sludge, and the coagulated sludge is then put into a filter, for example, in the form of a bag, . and statically drained.
The disadvantage of this method is that it is necessary to operate m~ny filter units in order to cope with the quantities of sludge thus obtained. Since the filters cannot be designed to just any size, the time required for draining the water is long.
In contrast to this method, in the process according 11;~2S37 to the invention a substantial number of filter units can be saved and at the same tlme much larger quantities of sludge can be concentrated within a shorter period of time when the clean water is removed from the sludge by an outside-in filtration in closed filter spaces and when the residual concentrated sludge is further drained in a conventional manner.
According to the present invention therefore there is D provided a process for concentrating a sludge from the m~niclpal or industrial sector which comprises feeding the sludge into a concentrator having disposed therein one or severai filters;
each said filter having porous walls such as filter fabric walls such that said sludge surroundssaid filter and clean water filters from the outside through said walls into a filter space, the cleaned water being drawn off from the filter space and thickened sludge being drawn off from the bottom of the concentrator.
Thus according to the present invention in the process for thickening sludge, clean water is drawn off by an outside-in filtration in aseparate filter space and the residual thickened sludge is further concentrated in a conventional manner.
With this method of draining the clean water into the filter, it is usually possible to concentrate sludge types the 50/,~5 content of which is between 0.3 to 6~. The process is particularly favourable for types of sludge having solids contents `~
lower than 5~
The present invention provides an apparatus for use in concentrating a sludge from the municipal or industrial sector which comprises a concentrator having disposed therein at least one filter with porous walls such as filter fabric walls, means for feeding sludge into said concentrator so as to surround said filter whereby clean water passes through said porous walls into a filter space; means for withdrawing clean water from said filter space, and means for withdrawing concentrated sludge from : .
said concentrator, said filter having supporting elements.
Eurther advantages oF the process according to the lnventlon are:
1. Because of both the spontaneous separation of ~7ater and -the possibility of rapidly drawing off of a very larqe quantity of clean water the entire concentration process reauires a relatively short time.
Heretofore, it has been customary to concentrate dilute sludge, obtained in the treatment of water, in concen-trators by using large sludge-storage tanks, in which the physically bound water is released and removed while stirring.
The release of the water can be slightly accelerated by the addition of calcium oxide or iron sulphate. With many types of sludge usually not more than 30~6 of turbid water is drawn off by this method. Thus, for example, for concentrating a biological excess sludge containing approximately 0.6~ of dry solids in a 100-cu m concentrator without the use of a mechanical agitator but with the addition of lime as a conditioning agent and odor~reducing agent from 17 to 36 hours were required to draw off approximately 20% of turbid water from the sludge.
The expenditure of work required for the portionwise addition of the lime and mixing with the sludge was very high. The resulting degree of concentration of the sludge and of separating the water is relatively low.
~ ccording to another method water removal is so carried out by adding flocculating agents which consist of cation-active, D anion-active or non- nionil~substances or mixtures thereof depen-ding on the condition of the sludge, and the coagulated sludge is then put into a filter, for example, in the form of a bag, . and statically drained.
The disadvantage of this method is that it is necessary to operate m~ny filter units in order to cope with the quantities of sludge thus obtained. Since the filters cannot be designed to just any size, the time required for draining the water is long.
In contrast to this method, in the process according 11;~2S37 to the invention a substantial number of filter units can be saved and at the same tlme much larger quantities of sludge can be concentrated within a shorter period of time when the clean water is removed from the sludge by an outside-in filtration in closed filter spaces and when the residual concentrated sludge is further drained in a conventional manner.
According to the present invention therefore there is D provided a process for concentrating a sludge from the m~niclpal or industrial sector which comprises feeding the sludge into a concentrator having disposed therein one or severai filters;
each said filter having porous walls such as filter fabric walls such that said sludge surroundssaid filter and clean water filters from the outside through said walls into a filter space, the cleaned water being drawn off from the filter space and thickened sludge being drawn off from the bottom of the concentrator.
Thus according to the present invention in the process for thickening sludge, clean water is drawn off by an outside-in filtration in aseparate filter space and the residual thickened sludge is further concentrated in a conventional manner.
With this method of draining the clean water into the filter, it is usually possible to concentrate sludge types the 50/,~5 content of which is between 0.3 to 6~. The process is particularly favourable for types of sludge having solids contents `~
lower than 5~
The present invention provides an apparatus for use in concentrating a sludge from the municipal or industrial sector which comprises a concentrator having disposed therein at least one filter with porous walls such as filter fabric walls, means for feeding sludge into said concentrator so as to surround said filter whereby clean water passes through said porous walls into a filter space; means for withdrawing clean water from said filter space, and means for withdrawing concentrated sludge from : .
said concentrator, said filter having supporting elements.
Eurther advantages oF the process according to the lnventlon are:
1. Because of both the spontaneous separation of ~7ater and -the possibility of rapidly drawing off of a very larqe quantity of clean water the entire concentration process reauires a relatively short time.
- 2. Mechanical agitators (raking mechanisms) for separating the water from the sludge and additional solids-forming inorganic conditioning agents are not required.
3. The spontaneously liberated clean water can be drawn off at the same rate as that of inflow of the sludge so that the sludqe can be concentrated continuously. This results in a substantial increase in the throughput in the concentrator thickeners.
4. Insufficient concentrator volumes can thus be increased with-out additional investment, or the size of `a newly designed concentrator can be initially reduced.
5. The clean water which is low in solids can be passed on for immediate reuse.
6. Even those sludge types which are subject to phase separation when the water is removed can be concentrated without problems.
7. When using more concentrated sludge types to be fed to 51udqe-di~estion tanks aclvantages are obtained due particularly ~- - 3 -.~
llZ2S37 to lower heat rec~uirement, higher gasyields, increased avail-ability of nutrients and increased capacity of the volume of the sludge-digestion tank. Moreover the costs of removing or dumping the sludge are also reduced.
Furthermore, concentrated, flocculated sludge types tend to rot less and thus are less odorous.
It is also possible to adapt the filters used in the individual cases more effectively to the relative requirements since their shapes can vary greatly. In its simplest construc-tion this filter is conventional filtering bag which is suspen-ded in the concentrator.
Depending on kind and properties of the sludge, filters used, for example, in the treatment of floating sludge, can have the shape of an upright inverted truncated pyramid. ~i-lters having the shape of an inverted truncated pyramid are used for a sludge which easily slides down on the filter. Prismatic and cylindrical filters are suitable for narrow and deep concentrat-ors. Truncated-cone-shaped filters are suitable for readily settling thick sludge types. In relatively flat concentrators in which a high degree of concentration is to be attained by long water-removal times prismatic or truncated-cone filters having large bottom surfaces are suitable.
The filter itself can be made of natural or synthetic substances or of metals. They may have the shapes described and can be provided with holes or slots. r~eaves or braids of natural or synthetic fibres or of metallic strands or mixtures thereof can also be used, Synthetic abrics, particularly those of polyester fibres, are preferably used, In order to prevent filters con-sisting of fibre material from being compressed, they can beprovided with supporting elements such as rings or lattice cages.
According to the process of the present invention the l~;ZZ537 c~r)(~ tralol- js c~arg~d \~it:h ~lud-3e lo wh;ch a flo~colatin(~ c~3enl has desiral~lv been aclded prior to feeding the slud(~e to ~he conc~n-trator. Depending on the kind of sludge, cation--active, dnion-active or non-ionic substances or even their mixtures are added as flocculating agents. The concentrator contains one or several filters ha~ing shapes adapted to the conditions in each case, as descrihed hereinbefore. The volume of the filter is only a fraction of the useful volume of the concentrator.
The sludge level in the concentrator and the level of clean water being separated in the filter are at the same height.
At the start of the slud~e concentration the concen-trator is filled with flocculated sludge up to approximately ~0% of its volume, ';heleby clarified ~ater is collected readi'y in the filter~ This water can be drawn off by means of a pump. However, it is more advantageous if the con-centrator is simultaneously refilled with fresh flocculated sludge in such a way that the amount of freshly added sludge approximately corresponds to the amount of clean ~ater drawn off.
Upon reachiny appro~imately one half of the desired Goncentration the addition of sludge is stopped but clean water continues to ~e dra~n o~f from the filter. Since the filters used ar~ movable, the concentrating process can even be carried on ~y co~ cs~orldingly lo~ering the filters into the sludge pres-ent until the concentrator is filled with only 30 to 35% of sludge. After completing the concentrating process the sludge either is fed to a sludge-di~estion tank or the water is removed from i~ in a conv2n~ional manner.
The present invention will be further illustrated by way of the accompanying drawings in which the single figure is a ~0 schematic vertical section through a concentrator for use in the process accordingly to one embodiment of the present invention.
Referring to the single figure, the concentrator 1 has -~ ~lZZS3~7 disposcd therein a filter 2. Sludge from the municipal or industrial sector is introduced in the concentrator l and thickened sludge is removed through output 3 from the bottom of the concentrator l for further conventional -treatment.
Durinq its presence in the concentrator l, clean water is filtered from the sludge and passes inwardly through the ~ilter material 4 on the supporting screen 5 of the filter 2 and into the filter space 6, from which it is pumped by either the suction pump 7 or the immersion pump 8 through line 9. The rate of introduction of the sludge into the concentrator 1, the rate of removal of thickened sludge from the concentrator l and the rate of removal of clean water from the filter space 6 is initi-ally such that the level 10 of the sludge in the concentrator l and the level o the water in the filter space 6 is essentially the same. Subsequently, the level 10 of the sludge in the concentrator 1 is allowed to drop by stopping introduction of sludge into the concentrator 1 and the filter 2 is lowered accordingly in the concentrator 1 by the devices (not shown).
The present invention will be further illustrated by way of the followinq Examples:
~xample 1 Approximately 58 cu m of biological excess sludge (solid content 0.6%), which is mixed with an intensely cationic 10cculating agent based on ployacrylic amide with a ~uaternary ammonium group, is pumped into an approximately 90 cu m sludge concentrator over 50 minutes. While flocculating coarsely, water is separated from the sludge spontaneously.
A circular filter consisting of polyester fibres and havinq a diameter of one metre, a length of three metres and a width of mesh of 0.5 to 3 mm is secured to four clamping rings, ~ - 6 .,~-., - ~Z2S37 weighted and suspended in the sludge concen-trator. A coarse supportiny lattice is also inserted in the lower portion of the filter. Within 45 minutes 28 cu m of clean water are drained from the filter by means of a pump. Thus, within 95 minutes a reduction in volume to one half is attained and the solids content is doubled. Further 10 cu m of clean water are drawn off upon lowering the filter into the thickened sludge at reduced pump capacity within one hour. The residual sludge has a volume of approximately 18 cu m and a solids content of approximately 2% .
The solids content in the sludge thus has increased to 3.3 times the initial amount. The water can be drained from the sludge thus preconcentrated in a conventional manner without further addition of flocculating agents, for example, by static draining in a polyester filter to a dry material content of approximately 6~.
Example 2 A filter iS suspended in an approximately 90 cu m sludge concentrator as described in Example 1. I~ithin one hour the concentrator is filled with 66 cu m of biological excess sludge having a dry material content of 0,6~ and containing 25g of intensely cation-ac-tive flocculating agent per cu m. Within this period the sludge level in the concentrator and the clean water level in the filter have reached the same height. The charging with sludge was then continued Eor 3 hours at the rate of approximately 60 cu m per hour while simultaneously draining approximately 65 cu m of clean water from the filter. The volume of sludge remaining in the sludge concentrator, i.e., approximately 70 cu m, was subsequently reduced to approximately 30 cu m by additionally draining off water. Thus, according to this method240 cu m of thin sludge in the sludge concentrator used were thickened to a volume of approximately 70 cu m within four hours corresponding appro~imately to a quaclruple thickening at a solid content of approximately 2.1~.
Further removal of water without additionally filling the sludge concentrator resulted in a thickening of the sludge to approximately 4.9% within one hour correspondin~ to a eight-fold thickening in approximately 5 hours.
Example 3 A filter contracted downwards and reinforced by iron bars and having a volume of approximately 13 cu m is suspended in an inclined position in a fixed rectangular sluclge concentra-tor having a content of approximately 100 cu m. The filter consists of coarse steel lattice material which is covered with a wire-mesh screen of approximately 2 mm width of mesh.
Approximately 50 eu m of activated sludge flocculated with 80 g/cu m of a weakly cation-active flocculating agent based on polyacrylic amide are fed to this concentrator within one hour.
The content of dry substance in the activated sludge is approximately 4%. The coagulated, coarse 10cculated sludg~
yields its water spontaneously. The sludge level in the sludge eoneentrator and the elean Wa~ter level in the filter are of approximately the same height.
When the sludge concentrator contains approximately 75 eu m of sluclge the concentrator is further charged while simultaneously draining clean water from the filter by means of a pump, the capacity of which can be varied. ~y means of this eontinuous process further 110 cu m of activated sludge can be fed to the sludge concentrator within 2.5 hours and concentrated to a volume of approximately ~5 cu m. The feed of sludge is then stopped but the water is drawn off for a further hour. In this manner approximately 25 cu m of clean water can be drawn off.
llZ2S37 to lower heat rec~uirement, higher gasyields, increased avail-ability of nutrients and increased capacity of the volume of the sludge-digestion tank. Moreover the costs of removing or dumping the sludge are also reduced.
Furthermore, concentrated, flocculated sludge types tend to rot less and thus are less odorous.
It is also possible to adapt the filters used in the individual cases more effectively to the relative requirements since their shapes can vary greatly. In its simplest construc-tion this filter is conventional filtering bag which is suspen-ded in the concentrator.
Depending on kind and properties of the sludge, filters used, for example, in the treatment of floating sludge, can have the shape of an upright inverted truncated pyramid. ~i-lters having the shape of an inverted truncated pyramid are used for a sludge which easily slides down on the filter. Prismatic and cylindrical filters are suitable for narrow and deep concentrat-ors. Truncated-cone-shaped filters are suitable for readily settling thick sludge types. In relatively flat concentrators in which a high degree of concentration is to be attained by long water-removal times prismatic or truncated-cone filters having large bottom surfaces are suitable.
The filter itself can be made of natural or synthetic substances or of metals. They may have the shapes described and can be provided with holes or slots. r~eaves or braids of natural or synthetic fibres or of metallic strands or mixtures thereof can also be used, Synthetic abrics, particularly those of polyester fibres, are preferably used, In order to prevent filters con-sisting of fibre material from being compressed, they can beprovided with supporting elements such as rings or lattice cages.
According to the process of the present invention the l~;ZZ537 c~r)(~ tralol- js c~arg~d \~it:h ~lud-3e lo wh;ch a flo~colatin(~ c~3enl has desiral~lv been aclded prior to feeding the slud(~e to ~he conc~n-trator. Depending on the kind of sludge, cation--active, dnion-active or non-ionic substances or even their mixtures are added as flocculating agents. The concentrator contains one or several filters ha~ing shapes adapted to the conditions in each case, as descrihed hereinbefore. The volume of the filter is only a fraction of the useful volume of the concentrator.
The sludge level in the concentrator and the level of clean water being separated in the filter are at the same height.
At the start of the slud~e concentration the concen-trator is filled with flocculated sludge up to approximately ~0% of its volume, ';heleby clarified ~ater is collected readi'y in the filter~ This water can be drawn off by means of a pump. However, it is more advantageous if the con-centrator is simultaneously refilled with fresh flocculated sludge in such a way that the amount of freshly added sludge approximately corresponds to the amount of clean ~ater drawn off.
Upon reachiny appro~imately one half of the desired Goncentration the addition of sludge is stopped but clean water continues to ~e dra~n o~f from the filter. Since the filters used ar~ movable, the concentrating process can even be carried on ~y co~ cs~orldingly lo~ering the filters into the sludge pres-ent until the concentrator is filled with only 30 to 35% of sludge. After completing the concentrating process the sludge either is fed to a sludge-di~estion tank or the water is removed from i~ in a conv2n~ional manner.
The present invention will be further illustrated by way of the accompanying drawings in which the single figure is a ~0 schematic vertical section through a concentrator for use in the process accordingly to one embodiment of the present invention.
Referring to the single figure, the concentrator 1 has -~ ~lZZS3~7 disposcd therein a filter 2. Sludge from the municipal or industrial sector is introduced in the concentrator l and thickened sludge is removed through output 3 from the bottom of the concentrator l for further conventional -treatment.
Durinq its presence in the concentrator l, clean water is filtered from the sludge and passes inwardly through the ~ilter material 4 on the supporting screen 5 of the filter 2 and into the filter space 6, from which it is pumped by either the suction pump 7 or the immersion pump 8 through line 9. The rate of introduction of the sludge into the concentrator 1, the rate of removal of thickened sludge from the concentrator l and the rate of removal of clean water from the filter space 6 is initi-ally such that the level 10 of the sludge in the concentrator l and the level o the water in the filter space 6 is essentially the same. Subsequently, the level 10 of the sludge in the concentrator 1 is allowed to drop by stopping introduction of sludge into the concentrator 1 and the filter 2 is lowered accordingly in the concentrator 1 by the devices (not shown).
The present invention will be further illustrated by way of the followinq Examples:
~xample 1 Approximately 58 cu m of biological excess sludge (solid content 0.6%), which is mixed with an intensely cationic 10cculating agent based on ployacrylic amide with a ~uaternary ammonium group, is pumped into an approximately 90 cu m sludge concentrator over 50 minutes. While flocculating coarsely, water is separated from the sludge spontaneously.
A circular filter consisting of polyester fibres and havinq a diameter of one metre, a length of three metres and a width of mesh of 0.5 to 3 mm is secured to four clamping rings, ~ - 6 .,~-., - ~Z2S37 weighted and suspended in the sludge concen-trator. A coarse supportiny lattice is also inserted in the lower portion of the filter. Within 45 minutes 28 cu m of clean water are drained from the filter by means of a pump. Thus, within 95 minutes a reduction in volume to one half is attained and the solids content is doubled. Further 10 cu m of clean water are drawn off upon lowering the filter into the thickened sludge at reduced pump capacity within one hour. The residual sludge has a volume of approximately 18 cu m and a solids content of approximately 2% .
The solids content in the sludge thus has increased to 3.3 times the initial amount. The water can be drained from the sludge thus preconcentrated in a conventional manner without further addition of flocculating agents, for example, by static draining in a polyester filter to a dry material content of approximately 6~.
Example 2 A filter iS suspended in an approximately 90 cu m sludge concentrator as described in Example 1. I~ithin one hour the concentrator is filled with 66 cu m of biological excess sludge having a dry material content of 0,6~ and containing 25g of intensely cation-ac-tive flocculating agent per cu m. Within this period the sludge level in the concentrator and the clean water level in the filter have reached the same height. The charging with sludge was then continued Eor 3 hours at the rate of approximately 60 cu m per hour while simultaneously draining approximately 65 cu m of clean water from the filter. The volume of sludge remaining in the sludge concentrator, i.e., approximately 70 cu m, was subsequently reduced to approximately 30 cu m by additionally draining off water. Thus, according to this method240 cu m of thin sludge in the sludge concentrator used were thickened to a volume of approximately 70 cu m within four hours corresponding appro~imately to a quaclruple thickening at a solid content of approximately 2.1~.
Further removal of water without additionally filling the sludge concentrator resulted in a thickening of the sludge to approximately 4.9% within one hour correspondin~ to a eight-fold thickening in approximately 5 hours.
Example 3 A filter contracted downwards and reinforced by iron bars and having a volume of approximately 13 cu m is suspended in an inclined position in a fixed rectangular sluclge concentra-tor having a content of approximately 100 cu m. The filter consists of coarse steel lattice material which is covered with a wire-mesh screen of approximately 2 mm width of mesh.
Approximately 50 eu m of activated sludge flocculated with 80 g/cu m of a weakly cation-active flocculating agent based on polyacrylic amide are fed to this concentrator within one hour.
The content of dry substance in the activated sludge is approximately 4%. The coagulated, coarse 10cculated sludg~
yields its water spontaneously. The sludge level in the sludge eoneentrator and the elean Wa~ter level in the filter are of approximately the same height.
When the sludge concentrator contains approximately 75 eu m of sluclge the concentrator is further charged while simultaneously draining clean water from the filter by means of a pump, the capacity of which can be varied. ~y means of this eontinuous process further 110 cu m of activated sludge can be fed to the sludge concentrator within 2.5 hours and concentrated to a volume of approximately ~5 cu m. The feed of sludge is then stopped but the water is drawn off for a further hour. In this manner approximately 25 cu m of clean water can be drawn off.
-8--The b~lance of the thickening as described shows that in a 100-cu m sludge concentrator with a 75% utilization of its volume 185 cu m of activated sludge containing approximately 4%
of dry solids can be concentrated within 4 hours to a volume o approximately 85 cu m containing approximately 3.5% of dry substance. This corresponds to a thickening ratio of approximat-ely 1:2 2.
The removal of additional 25 cu m of clean water from the sludge results in a thickening to approximately 1 % of solids corresponding to a thickenin~ ratio of approximately 1:3 in 5 hours.
The process according to the invention is suitable for concentrating of the most diverse types of sludge as obtained in a variety of industrial plants, for example, in rinsing wa-ter of filters, in the metal working industry, in mining or in the municipal sector, for example, as turbid water from sludge-digestion to~ers.
Of course, the process according to the invention can also be applied to mobile plants.
g _ . . :
of dry solids can be concentrated within 4 hours to a volume o approximately 85 cu m containing approximately 3.5% of dry substance. This corresponds to a thickening ratio of approximat-ely 1:2 2.
The removal of additional 25 cu m of clean water from the sludge results in a thickening to approximately 1 % of solids corresponding to a thickenin~ ratio of approximately 1:3 in 5 hours.
The process according to the invention is suitable for concentrating of the most diverse types of sludge as obtained in a variety of industrial plants, for example, in rinsing wa-ter of filters, in the metal working industry, in mining or in the municipal sector, for example, as turbid water from sludge-digestion to~ers.
Of course, the process according to the invention can also be applied to mobile plants.
g _ . . :
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for concentrating a sludge from the municipal or industrial sector which comprises feeding the sludge into a concentrator having disposed therein at least one filter; said filter having porous walls such that said sludge surrounds said filter and clean water filters from the outside through said walls into a filter space, the cleaned water being drawn off from the filter space and thickened sludge being drawn off from the bottom of the concentrator.
2. A process according to claim 1, in which the porous walls are formed by a filter fabric.
3. A process according to claim 2, in which the filtration is effected in filters of natural or synthetic fibres or metal strands or fabrics of said fibres and strands either individually or in a mixture.
4. A process according to claim 3, in which the filters contain supporting elements.
5. A process as claimed in claim 1, 2 or 3, in which the filtration is effected continuously.
6. A process as claimed in claim 1, 2 or 3, in which the filtration is effected discontinuously.
7. A process as claimed in claim 1, 2 or 3, in which the sludge is pre-flocculated.
8. An apparatus for use in concentrating a sludge from the municipal or industrial sector which comprises a concentrator having disposed therein at least one filter with porous walls;
means for filtering sludge into said concentrator so as to surround said filter whereby clean water passes through said porous walls into a filter space; means for withdrawing clean water from said filter space; a means for withdrawing concentrated sludge from said concentrator; said filter having supporting elements.
means for filtering sludge into said concentrator so as to surround said filter whereby clean water passes through said porous walls into a filter space; means for withdrawing clean water from said filter space; a means for withdrawing concentrated sludge from said concentrator; said filter having supporting elements.
9. An apparatus as claimed in claim 8, in which the porous walls are formed by filter fabric.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2800278.0 | 1978-01-04 | ||
| DE19782800278 DE2800278A1 (en) | 1978-01-04 | 1978-01-04 | PROCESS FOR THICKENING OF Sludge |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122537A true CA1122537A (en) | 1982-04-27 |
Family
ID=6028961
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA314,450A Expired CA1122537A (en) | 1978-01-04 | 1978-10-26 | Process for thickening sludge |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0003013B1 (en) |
| CA (1) | CA1122537A (en) |
| DE (2) | DE2800278A1 (en) |
| DK (1) | DK536478A (en) |
| IT (1) | IT1100893B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5888026A (en) * | 1997-01-24 | 1999-03-30 | Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Natural Resources | Backfill paste production facility and method and apparatus for producing high density slurry and paste backfills |
| US6168352B1 (en) | 1997-01-24 | 2001-01-02 | Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Natural Resources | Apparatus for producing high density slurry and paste backfills |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2447286A (en) * | 1946-03-23 | 1948-08-17 | Carlos B Smith | Sludge settling and dewatering tank |
| GB1270803A (en) * | 1968-04-08 | 1972-04-19 | Dorr Oliver Company Ltd | Sludge treatment |
| DE1912133A1 (en) * | 1969-03-11 | 1970-09-17 | Schwimmbad Technik Franz Koehl | Filter device for mechanically soiled liquids - such as swimming baths |
| US3635343A (en) * | 1969-04-28 | 1972-01-18 | Richard W Holland | Filtration system |
-
1978
- 1978-01-04 DE DE19782800278 patent/DE2800278A1/en not_active Withdrawn
- 1978-10-26 CA CA314,450A patent/CA1122537A/en not_active Expired
- 1978-11-13 IT IT29716/78A patent/IT1100893B/en active
- 1978-11-29 DK DK536478A patent/DK536478A/en not_active Application Discontinuation
-
1979
- 1979-01-04 EP EP79100022A patent/EP0003013B1/en not_active Expired
- 1979-01-04 DE DE7979100022T patent/DE2963569D1/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5888026A (en) * | 1997-01-24 | 1999-03-30 | Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Natural Resources | Backfill paste production facility and method and apparatus for producing high density slurry and paste backfills |
| US6168352B1 (en) | 1997-01-24 | 2001-01-02 | Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Natural Resources | Apparatus for producing high density slurry and paste backfills |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2963569D1 (en) | 1982-10-21 |
| IT7829716A0 (en) | 1978-11-13 |
| EP0003013B1 (en) | 1982-08-25 |
| DK536478A (en) | 1979-07-05 |
| IT1100893B (en) | 1985-09-28 |
| EP0003013A1 (en) | 1979-07-11 |
| DE2800278A1 (en) | 1979-07-12 |
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