CA1069625A - Method of filtering liquids containing dissolved carbon dioxide - Google Patents
Method of filtering liquids containing dissolved carbon dioxideInfo
- Publication number
- CA1069625A CA1069625A CA256,874A CA256874A CA1069625A CA 1069625 A CA1069625 A CA 1069625A CA 256874 A CA256874 A CA 256874A CA 1069625 A CA1069625 A CA 1069625A
- Authority
- CA
- Canada
- Prior art keywords
- carbon dioxide
- effluent
- filtration
- liquid
- alkaline material
- 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
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 43
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 43
- 238000001914 filtration Methods 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 15
- 239000007788 liquid Substances 0.000 title abstract description 37
- 239000000463 material Substances 0.000 claims abstract description 20
- 230000003247 decreasing effect Effects 0.000 claims abstract description 7
- 239000006260 foam Substances 0.000 claims description 19
- 239000007787 solid Substances 0.000 claims description 15
- 238000013124 brewing process Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims description 2
- 239000000908 ammonium hydroxide Substances 0.000 claims description 2
- VKFFEYLSKIYTSJ-UHFFFAOYSA-N tetraazanium;phosphonato phosphate Chemical compound [NH4+].[NH4+].[NH4+].[NH4+].[O-]P([O-])(=O)OP([O-])([O-])=O VKFFEYLSKIYTSJ-UHFFFAOYSA-N 0.000 claims description 2
- 238000005187 foaming Methods 0.000 abstract description 5
- 230000008030 elimination Effects 0.000 abstract 1
- 238000003379 elimination reaction Methods 0.000 abstract 1
- 235000013405 beer Nutrition 0.000 description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 238000003828 vacuum filtration Methods 0.000 description 7
- 238000001704 evaporation Methods 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 6
- 239000000706 filtrate Substances 0.000 description 5
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000011045 prefiltration Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 244000144972 livestock Species 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052753 mercury Inorganic materials 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical group CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000000855 fermentation Methods 0.000 description 1
- 230000004151 fermentation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000010816 packaging waste Substances 0.000 description 1
- -1 potasiium hydro-ide Chemical compound 0.000 description 1
Landscapes
- Physical Water Treatments (AREA)
- Distillation Of Fermentation Liquor, Processing Of Alcohols, Vinegar And Beer (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
Abstract of the Disclosure A method of reducing foaming of a liquid containing dissolved carbon dioxide during filtering. The carbonated liquid to be filtered is adjusted in pH to a value of 6.5 to 8.0 by the addition of an alkaline material which reacts with the dissolved carbon dioxide to remove the carbon dioxide from solution. The elimination of the dissolved carbon dioxide results in decreasing foaming during filtering and substantially increases the rate of filtration.
Description
~0696Z5 sackground of the Invention In the normal brewing process there are a number of different liquid residues or effluen~s resultirg f~m the various operations-in the overall process. The liquid residues generally contain a small proportion of dissolved solids, and a small amount of suspended solids, primarily filter aid materials, as well as dissolved carbon dioxide.
In the past, the practice has merely been to discard the liquid residue, but due to pollution considerations, the recent practice has been to treat the liquid residue and remove protenaceous constituents. In~the removal treatment, the liquid is initially filtered to remove the suspended solids, and the filtrate is then evaporated. Due to the high concentration o protenaceous material, the concentrated filtrates can be used as a livestock feed. The solids removed by filtration are normally transported to a landfill site and discarded.
~ hen using vacuum filtration equipment ~ filter the liquid residue or effluent, tremendous quantities of foam are generated due to the dissolved carbon dioxide. It has been found that because of the reduction of pressure during filtration, the carbon dioxîde comes out of solution and carbon dioxide bubbles are adsorbed on the filter aid particles or other suspended foreign particles. The carbon dioxide bubbles continue to grow during the filtering oporation and cannot be displaced,with the result that the porosity and permeability of the filter are substantially reduced, thereby substantially reducing the rate of filtration.
As a result of the dissolved carbon dioxide, a problem is also encountered in subsequent evaporation of the filtrate.
During evaporation the carbon dioxide will come out of solution so that a substantial head of foam is generated in the evapora-~o69625 tion vessel~ If the foam generation is not controlled, the foamcan overflow the vessel or back up into the other equipment.
Summary of the Invention The invention is directed to a method of reducing foam generation during processing of a carbonated liquid, and in particular, is directed to a method of preventing foaming of residual liquids from brewing processing during vacuum filtration.
The liquid to be filtered comprises a mixture of different liquid residues or effluents from the brewing process, and the liquid will generally contain about 1% to 2% by weight of suspended solids, about 2% to 3% by weight of dissolved solids, and approx-imately one~alf volume of carbon dioxide per volume of liquid.
The pH of the liquid is normally below 5.0 a~d generally in the range of about 3.8 to 4.5.
In accordance with the invention, a water soluble ! alkaline material, such as an alkali ~etal hydroxide, is added to the liquid in sufficient quantity to raise the pH to a value in the range of 6.5 to 8Ø The alkaline material will react with the dissolved carbon dioxide to form carbonates. The elimina~ion of the dissolved carbon dioxide`substantially decreases foam gen-eration during the vacuum filtration of the liquid and increases the rate of filtration. By eliminating the dissolved carbon dioxide, foam generation will also be substantially decreased in subsequent -~
processing operations such as evaporation of the filtrate.
While foam generation is not a significant problem in : . .
pressure filtering operations, it has been found that the method of the invention, when used in pressure filtering operations, produces a substantial improvement in the rate of filtration.
Other objects and advantages will appear in the course of the following description , ' ' ~ , ~ , . . .
Description of the Drawings The drawings illustrate the best mode presently contemplated of carrying out the invention~
In the drawings:
Fig. 1 is a cu-rve showing the relationship between foam generation and pH of prefiltered beer; and Fig. 2 is a curve showing the relation between the rate of filtration and pH for prefiltered beer.
Des~ription of the Preferred Em~odiment The normal brewing process produces a number of different ~iquid residues or effluents. These residues, for example, are the fermentation effluent, the ruh stump effluent, the prefilter heel effluent, the final filter heel effluent, the pre-filter.
surge tank effluent, the pre-filter accumulator tank effluent, the final filter surge effluent, the final filter accumulator effluent, the government cellar tank effluent, the celler transfer beer and packaging waste beer.
The various residual liquids or effluents are combined, and the liquid mixture, in general, contains from 1% to 2% by 20 weight o suspended solids, which are primarily filter aid :
materials, about 2% to 3% by weight of dissolved solids, and .
approximately one-half volume of carbon dioxide per volume o liquid. The liquid normally has a pH under 5.0 and usually in the range of 3.8 to 4.5.
According to the invention, an alkaline material is added to the liquid mixture prior to filtration in an amount . sufficient to raise the pH of the liquid to a value in the range of 6.5 to 8.0~ The alkaline material should be water soluble and .:
can take the form of materials such as alkali metal hydroxides, i,e. sodium hydroxide, potasiium hydro-ide, or lithium hydroxide;
. . .
.
.
. .
~o69625 ammonium hydroxide; or ammonium pyrophosphate. The alkaline material reacts with the dissolved carbon dioxide to remove the carbon dioxide from solution~ It is preferred t~.at ~he alkaline material contain metal ions that will form water soluble carbon-ates on reaction with the carbon dioxide, but if the alkalinematerial contains metal ions that form insoluble carbonates, the insoluble carbonates will be removed during the subsequent filter-ing operation.
After the addition of the alkaLine material to raise the pH of the liquid to the a~orementioned range, the liquid is filtered by a conventional vacuum type filter, such as a leaf filter, rotary drum filter, belt filter, Buchner filterJ or the like.
It has been found that dissolved carbon dioxide produces tremendous quantities of foam during the vacuum filtration. The ! reduction in pressure during the vacuum filtration will re~ult in the carbon dioxide coming out of solution, and carbon dioxide gas bubbles will be adsorbed on the suspended particles, such as fîlter aid particles and other suspended solids. The adsorbed carbon dioxide bubbles will progressively grow in size and are difficult to displace. This p~enomenon greatly decreas~ the poro~ity and permeability of the filter and substantially reduces the rate of filterion. However, by the addition of the alkaline material, in accordance with the method of the invention,the diasolved carbon dioxide is eliminated and foam generation result-ing from dissolution of the carbon dioxide during vacuum filtra-tion is correspondingly eliminated.
Some oaming due to the agitation of the liquid may still exist, but foaming due to mechanical agitation will not ~adversely effect the rate of filtration~
, _4_ , - ' ~
'io696Z5 The amount of the alkaline material to be added should preferably be sufficient to remove all of the dissolved carbon dioxide, and a pH in the treated liquid of over 6.5 indicates the substantial removal of the dissolved carbon dioxide~ On the other hand, if the pH of the liquid is over 8.0, proteinaceous materials may be precipitated which can adversely effect the filtering operation.
If a pressure type of filter operation is employed in which a positive pressure is applied to the liquid during filtra-tion in excess of about 10 psig, the carbon dioxide will bemaintained in solution and no foaming due to the dissolution of carbon dioxide will result~ However, it has been found that even with pressure filtering there is a correlation between the amount of carbon dioxide in solution and the rate of filtration, i.e. as the quantity of dissalved carbon dioxide is increased, the rate of filtration will be decreased. Thus, the removal of carbon dioxide ~rom solution will in~rease the rate of filtration both in vacuum and pressure type filtering processes.
As a further advantage, the removal of the carbon dioxide a~ds in subsequent processing of the liquid. For example, after filtrationJ the filtrate, due to the high concentration of protenaceous materials in the dissolved solids, is normally evaporated or concentrated and the concentra~e used as a livestock feed. During evaporation~the presence of dissolved carbon dioxide will also result in substantial generation of foam which can overflow the evaporation vessel and back up into other equipment unless precautionary measures are taken. By removal of the carbon dioxide, the foam generation is substantially eliminated during subsequent processing, such as evaporation.
~ The following examples illustrate the process of the invention:
_5_ : :
~, ~ , . ..
- .
. .
EXA~PLE
A series of tests were conducted to show the relation-ship between the pH and foam generation of prefiltered beer. The pre-filtered beer contained about 1 volu~e of carbon dioxide per volume of beer, a substantially greater proportion of carbon dioxide than in the residual brewing effluents, which lS normally about 1/2 the volume of carbon dioxide per volume of liquid. In these tests, a series of samples of the pre-filtered beer were treated with different amounts of sodium hydroxide to provide p~'s in the range of 4.0 to 12Ø Each of the samples was then filtered with a vacuum, precoated, leaf filter using diamataceous earth as the filter aid and a vacuum of 24 inches of mercury.
An average of ten readings were used for eac~ sample. During the filtration, the volumetric foam-liquid ratio was determined by use of a ~alibrated filtration collection tube.
I The results of the tests showing the foam generation at various pH are illustrated in Fig. 1. As shown in the curve in Fig. 1, the foam-liquid ratio increased sharply as the pH was raised from 4.0 to 5.0 and then abruptly decreased to a minimNm ~oam-liquid ratio at a pH of about 7.2. The foam generation increased slightly at a pH of 8~0 and then remained fairly constant at pH from 8.0 to 12Ø These tests illustrate the unusual drop in foam generation during vacuum filtering brought about by the raising of the pH through use of the aIkaline material to a value in the range of about 6.5 to 8Ø
EXAMPLE II
A series of tests were conducted LO compare the filtra- -tion rate of a liquid containing dissolved carbon dioxide at various pH values. Pre-filtered beer was employed in these tests 3D ard con,ained approximQtely 1 volume of carbon dioxide per volume .
- -. ~ .
~0696Z5 of beer. A series of samples of pre-filtered beer were treated with sodium hydroxide in amounts sufficient to pro~ide the various sampLes with pH's ranging from 4.0 to 12.0 Each of the samples was filtered through a vacuum leaf filter precoated with diatamaceous earth as the filter aid~ A vacuum of 24 inches of mercury was utilized. An average of ten readings were used for each sample.
The results of the tests comparing the filtration rate with pH are shown in Fig. 2. As illustrated in the curve, the filtration rate initially decreased as the pH was raised from 4.0 to 5.0 and then sharply increased to a maximum filtration rate at a pH of 7.2. The filtration rate then decreased as the pH was increased to a value o 10.5.
The curve of Fig. 2 illustrates the unusual and unexpected ~5 change in the filtratinn rate brought about by a change in pH and ~- illustrates that the maximum filtration rate is obtained at a pH
of about ~Ø
The method of the invention provides a substantial decrease in the generation of foam during vacuum filtration o~ ~
20 carbonated liquids, as well as providing an improved filtration --rate. Whîle the invention has particular application to a vacuum filtering operation,it`can also ~e employed with pressure filter-ing operations in which case the method ofthe invention will act to increase the filtration rate, although foam generation under pressure conditions is not a problem.
; :~ :
: :
, .; ~ , . ':
: .
., ,. ~ .
. ~ . .
. .
In the past, the practice has merely been to discard the liquid residue, but due to pollution considerations, the recent practice has been to treat the liquid residue and remove protenaceous constituents. In~the removal treatment, the liquid is initially filtered to remove the suspended solids, and the filtrate is then evaporated. Due to the high concentration o protenaceous material, the concentrated filtrates can be used as a livestock feed. The solids removed by filtration are normally transported to a landfill site and discarded.
~ hen using vacuum filtration equipment ~ filter the liquid residue or effluent, tremendous quantities of foam are generated due to the dissolved carbon dioxide. It has been found that because of the reduction of pressure during filtration, the carbon dioxîde comes out of solution and carbon dioxide bubbles are adsorbed on the filter aid particles or other suspended foreign particles. The carbon dioxide bubbles continue to grow during the filtering oporation and cannot be displaced,with the result that the porosity and permeability of the filter are substantially reduced, thereby substantially reducing the rate of filtration.
As a result of the dissolved carbon dioxide, a problem is also encountered in subsequent evaporation of the filtrate.
During evaporation the carbon dioxide will come out of solution so that a substantial head of foam is generated in the evapora-~o69625 tion vessel~ If the foam generation is not controlled, the foamcan overflow the vessel or back up into the other equipment.
Summary of the Invention The invention is directed to a method of reducing foam generation during processing of a carbonated liquid, and in particular, is directed to a method of preventing foaming of residual liquids from brewing processing during vacuum filtration.
The liquid to be filtered comprises a mixture of different liquid residues or effluents from the brewing process, and the liquid will generally contain about 1% to 2% by weight of suspended solids, about 2% to 3% by weight of dissolved solids, and approx-imately one~alf volume of carbon dioxide per volume of liquid.
The pH of the liquid is normally below 5.0 a~d generally in the range of about 3.8 to 4.5.
In accordance with the invention, a water soluble ! alkaline material, such as an alkali ~etal hydroxide, is added to the liquid in sufficient quantity to raise the pH to a value in the range of 6.5 to 8Ø The alkaline material will react with the dissolved carbon dioxide to form carbonates. The elimina~ion of the dissolved carbon dioxide`substantially decreases foam gen-eration during the vacuum filtration of the liquid and increases the rate of filtration. By eliminating the dissolved carbon dioxide, foam generation will also be substantially decreased in subsequent -~
processing operations such as evaporation of the filtrate.
While foam generation is not a significant problem in : . .
pressure filtering operations, it has been found that the method of the invention, when used in pressure filtering operations, produces a substantial improvement in the rate of filtration.
Other objects and advantages will appear in the course of the following description , ' ' ~ , ~ , . . .
Description of the Drawings The drawings illustrate the best mode presently contemplated of carrying out the invention~
In the drawings:
Fig. 1 is a cu-rve showing the relationship between foam generation and pH of prefiltered beer; and Fig. 2 is a curve showing the relation between the rate of filtration and pH for prefiltered beer.
Des~ription of the Preferred Em~odiment The normal brewing process produces a number of different ~iquid residues or effluents. These residues, for example, are the fermentation effluent, the ruh stump effluent, the prefilter heel effluent, the final filter heel effluent, the pre-filter.
surge tank effluent, the pre-filter accumulator tank effluent, the final filter surge effluent, the final filter accumulator effluent, the government cellar tank effluent, the celler transfer beer and packaging waste beer.
The various residual liquids or effluents are combined, and the liquid mixture, in general, contains from 1% to 2% by 20 weight o suspended solids, which are primarily filter aid :
materials, about 2% to 3% by weight of dissolved solids, and .
approximately one-half volume of carbon dioxide per volume o liquid. The liquid normally has a pH under 5.0 and usually in the range of 3.8 to 4.5.
According to the invention, an alkaline material is added to the liquid mixture prior to filtration in an amount . sufficient to raise the pH of the liquid to a value in the range of 6.5 to 8.0~ The alkaline material should be water soluble and .:
can take the form of materials such as alkali metal hydroxides, i,e. sodium hydroxide, potasiium hydro-ide, or lithium hydroxide;
. . .
.
.
. .
~o69625 ammonium hydroxide; or ammonium pyrophosphate. The alkaline material reacts with the dissolved carbon dioxide to remove the carbon dioxide from solution~ It is preferred t~.at ~he alkaline material contain metal ions that will form water soluble carbon-ates on reaction with the carbon dioxide, but if the alkalinematerial contains metal ions that form insoluble carbonates, the insoluble carbonates will be removed during the subsequent filter-ing operation.
After the addition of the alkaLine material to raise the pH of the liquid to the a~orementioned range, the liquid is filtered by a conventional vacuum type filter, such as a leaf filter, rotary drum filter, belt filter, Buchner filterJ or the like.
It has been found that dissolved carbon dioxide produces tremendous quantities of foam during the vacuum filtration. The ! reduction in pressure during the vacuum filtration will re~ult in the carbon dioxide coming out of solution, and carbon dioxide gas bubbles will be adsorbed on the suspended particles, such as fîlter aid particles and other suspended solids. The adsorbed carbon dioxide bubbles will progressively grow in size and are difficult to displace. This p~enomenon greatly decreas~ the poro~ity and permeability of the filter and substantially reduces the rate of filterion. However, by the addition of the alkaline material, in accordance with the method of the invention,the diasolved carbon dioxide is eliminated and foam generation result-ing from dissolution of the carbon dioxide during vacuum filtra-tion is correspondingly eliminated.
Some oaming due to the agitation of the liquid may still exist, but foaming due to mechanical agitation will not ~adversely effect the rate of filtration~
, _4_ , - ' ~
'io696Z5 The amount of the alkaline material to be added should preferably be sufficient to remove all of the dissolved carbon dioxide, and a pH in the treated liquid of over 6.5 indicates the substantial removal of the dissolved carbon dioxide~ On the other hand, if the pH of the liquid is over 8.0, proteinaceous materials may be precipitated which can adversely effect the filtering operation.
If a pressure type of filter operation is employed in which a positive pressure is applied to the liquid during filtra-tion in excess of about 10 psig, the carbon dioxide will bemaintained in solution and no foaming due to the dissolution of carbon dioxide will result~ However, it has been found that even with pressure filtering there is a correlation between the amount of carbon dioxide in solution and the rate of filtration, i.e. as the quantity of dissalved carbon dioxide is increased, the rate of filtration will be decreased. Thus, the removal of carbon dioxide ~rom solution will in~rease the rate of filtration both in vacuum and pressure type filtering processes.
As a further advantage, the removal of the carbon dioxide a~ds in subsequent processing of the liquid. For example, after filtrationJ the filtrate, due to the high concentration of protenaceous materials in the dissolved solids, is normally evaporated or concentrated and the concentra~e used as a livestock feed. During evaporation~the presence of dissolved carbon dioxide will also result in substantial generation of foam which can overflow the evaporation vessel and back up into other equipment unless precautionary measures are taken. By removal of the carbon dioxide, the foam generation is substantially eliminated during subsequent processing, such as evaporation.
~ The following examples illustrate the process of the invention:
_5_ : :
~, ~ , . ..
- .
. .
EXA~PLE
A series of tests were conducted to show the relation-ship between the pH and foam generation of prefiltered beer. The pre-filtered beer contained about 1 volu~e of carbon dioxide per volume of beer, a substantially greater proportion of carbon dioxide than in the residual brewing effluents, which lS normally about 1/2 the volume of carbon dioxide per volume of liquid. In these tests, a series of samples of the pre-filtered beer were treated with different amounts of sodium hydroxide to provide p~'s in the range of 4.0 to 12Ø Each of the samples was then filtered with a vacuum, precoated, leaf filter using diamataceous earth as the filter aid and a vacuum of 24 inches of mercury.
An average of ten readings were used for eac~ sample. During the filtration, the volumetric foam-liquid ratio was determined by use of a ~alibrated filtration collection tube.
I The results of the tests showing the foam generation at various pH are illustrated in Fig. 1. As shown in the curve in Fig. 1, the foam-liquid ratio increased sharply as the pH was raised from 4.0 to 5.0 and then abruptly decreased to a minimNm ~oam-liquid ratio at a pH of about 7.2. The foam generation increased slightly at a pH of 8~0 and then remained fairly constant at pH from 8.0 to 12Ø These tests illustrate the unusual drop in foam generation during vacuum filtering brought about by the raising of the pH through use of the aIkaline material to a value in the range of about 6.5 to 8Ø
EXAMPLE II
A series of tests were conducted LO compare the filtra- -tion rate of a liquid containing dissolved carbon dioxide at various pH values. Pre-filtered beer was employed in these tests 3D ard con,ained approximQtely 1 volume of carbon dioxide per volume .
- -. ~ .
~0696Z5 of beer. A series of samples of pre-filtered beer were treated with sodium hydroxide in amounts sufficient to pro~ide the various sampLes with pH's ranging from 4.0 to 12.0 Each of the samples was filtered through a vacuum leaf filter precoated with diatamaceous earth as the filter aid~ A vacuum of 24 inches of mercury was utilized. An average of ten readings were used for each sample.
The results of the tests comparing the filtration rate with pH are shown in Fig. 2. As illustrated in the curve, the filtration rate initially decreased as the pH was raised from 4.0 to 5.0 and then sharply increased to a maximum filtration rate at a pH of 7.2. The filtration rate then decreased as the pH was increased to a value o 10.5.
The curve of Fig. 2 illustrates the unusual and unexpected ~5 change in the filtratinn rate brought about by a change in pH and ~- illustrates that the maximum filtration rate is obtained at a pH
of about ~Ø
The method of the invention provides a substantial decrease in the generation of foam during vacuum filtration o~ ~
20 carbonated liquids, as well as providing an improved filtration --rate. Whîle the invention has particular application to a vacuum filtering operation,it`can also ~e employed with pressure filter-ing operations in which case the method ofthe invention will act to increase the filtration rate, although foam generation under pressure conditions is not a problem.
; :~ :
: :
, .; ~ , . ':
: .
., ,. ~ .
. ~ . .
. .
Claims (4)
1. A method of filtering effluent from a brewing process, comprising the steps of collecting residual aqueous effluent from a brewing process, said effluent containing suspended solids, dissolved solids and dissolved carbon dioxide and having a pH less than 5.0, adding a water soluble alkaline material to said collected effluent to increase the pH to the range of 6.5 to 8.0, said alkaline material reacting with said carbon dioxide to substantially remove the carbon dioxide from solution, and thereafter filtering said collected effluent to remove the suspended solids, the removal of carbon dioxide decreasing foam generation during filtration and substantially increasing the rate of filtration.
2. The method of claim 1, wherein the effluent contains about 1% to 2% by weight of suspended solids and about 2% to 3% by weight of dissolved solids.
3. The method of claim 1, wherein the step of filter-ing is carried out under sub-atmospheric pressure.
4. The method of claim 1, wherein the alkaline material is selected from the group consisting of alkali metal hydroxides, ammonium hydroxide and ammonium pyrophosphate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA256,874A CA1069625A (en) | 1976-07-13 | 1976-07-13 | Method of filtering liquids containing dissolved carbon dioxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA256,874A CA1069625A (en) | 1976-07-13 | 1976-07-13 | Method of filtering liquids containing dissolved carbon dioxide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069625A true CA1069625A (en) | 1980-01-08 |
Family
ID=4106419
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA256,874A Expired CA1069625A (en) | 1976-07-13 | 1976-07-13 | Method of filtering liquids containing dissolved carbon dioxide |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1069625A (en) |
-
1976
- 1976-07-13 CA CA256,874A patent/CA1069625A/en not_active Expired
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| MKEX | Expiry |