CA1038562A - Method of purifying effluents from forest industries - Google Patents
Method of purifying effluents from forest industriesInfo
- Publication number
- CA1038562A CA1038562A CA202,221A CA202221A CA1038562A CA 1038562 A CA1038562 A CA 1038562A CA 202221 A CA202221 A CA 202221A CA 1038562 A CA1038562 A CA 1038562A
- Authority
- CA
- Canada
- Prior art keywords
- resin
- effluent
- bed
- liquid
- resin bed
- 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
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J41/00—Anion exchange; Use of material as anion exchangers; Treatment of material for improving the anion exchange properties
- B01J41/04—Processes using organic exchangers
- B01J41/07—Processes using organic exchangers in the weakly basic form
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/26—Treatment of water, waste water, or sewage by extraction
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/26—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof
- C02F2103/28—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof from the paper or cellulose industry
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Treatment Of Water By Ion Exchange (AREA)
- Paper (AREA)
Abstract
TITLE OF THE INVENTION
" METHOD OF PURIFYING EFFLUENTS FROM FOREST INDUSTRIES "
A B S T R A C T
In a process for decolouring wood pulp mill effluent, particulary that from the alkaline extraction stage in wood pulp bleaching, by passing the effluent through a bed of an acid activated phenolic anion exchange resin, the formation of channels in the resin bed is minimised and consequently the efficiency of the decolouring improved, by treating the resin bed with an aqueous acid while the effluent is being decolouring in the resin bed.
" METHOD OF PURIFYING EFFLUENTS FROM FOREST INDUSTRIES "
A B S T R A C T
In a process for decolouring wood pulp mill effluent, particulary that from the alkaline extraction stage in wood pulp bleaching, by passing the effluent through a bed of an acid activated phenolic anion exchange resin, the formation of channels in the resin bed is minimised and consequently the efficiency of the decolouring improved, by treating the resin bed with an aqueous acid while the effluent is being decolouring in the resin bed.
Description
~S62 ~
The present invention relates to a method of reducing the content of pollutants which are lignin or lignin ~ ;
degradation products in the aqueous eff:Luent from forest . :
industries working with cellulose conta:Lning produ~cts. The method is primarily applicable to the treatment of chemical pulp~
mill effluent, e.g. bleached plant waste liquor from such mills but can also be used to treat other effluents $~ containing lignin degradation products, such as screening plant '~ effluent, e.g. back water from su}phite screening plants~
, 10 alkaline condensates etc In our Canadian Patent ~o. 987459 issued April 20th .~:
~! 1976 we describe and claim a method of reducing the content l of lignin degradation products in the aqueous ef~luent from forest and other industries working with cellulose containing I5 products which comprises bringlng the effluent into contact~
with a porous and granular phenollc resln which~will~absorb~
:3~ the lignin and lignln derivatlves~from the effluent~ séparating ;~
an effluent of reduced lignin and~lignin derivative~content and recirculatlng lt or discharging it to an outflow;~and~
eluting the resin to ;recover the lignin and llgnin;derivatives ~ for disposal.
J~ In the operation of this method on full plant`~scale,~
t~is desirable to~be~able to~maximise the num~er~of bed valumes~
of~effluent that;~can be treated~to~give~adequate~decolouratlon ;~
; 25~ ~of the~effluent~before lt ls necessary to elute the resln. ;
We~have now found~that one reason~for the falling~off in the ~l~ ability of the~resin to decolour the effluent is that the volume of the~resin Ls~influenced by the pH of its~environmént and ~ -;~ ; that changes in environmental~pH bring about chang~s in ~the ~: : ~: ` :: `
~ 30 resin volume and this in turn may bring about the~formation of _ _ .......... _ ,_~_~ . ~ . .... . . . .. .
channels in the resin bed which reduces the ability o~ the re~in to decolour the effluent. The present invention provides ; ;
a method of ~ubstantially eliminating this problem.
In one aspect of the present invention, in a method of reducing the content of organic pollutants which are lignin or lignin degradation products in an aqueous effluent solution ~ ~
from forest industries working with cellulose containing`
products which comprises passing the aqueous effluent solution through a bed of a porous and granular phenolic resin which will take up the pollutants from the effluent, said resin being ;
of a type whose volume changes with change of the pH of the liquid phase in which the resin is located, separating an effluent of reduced pollutant content and eluting the~resin to remove the pollutants for disposal and regenerate the resin for i further use, we provide the improvement which comprises minimising volume changes inthe resin bed by batchwise addikion of an aqueous acid solution to the resin bed so that the pH of the li~uid phase in which the resin is located is~repeatedly lowered during treatment o~ the effluent whereby formation of channels in the resin bed is ubstantially eliminated. ~` ;
In another aspect of the present invention ln a method~ ;
of binding solute which is lignin or lignin degradation products ~
, .
dis~olved in an aqueous effluent solution, said methocl comprising~
~a) preparing a bed of a phenolic resin capable of `
binding said solute, said resin bed being a bed which changes its volume with change of pH of the liquid phase in which the resin is located, by passing through the resin bed an acidic first liquid having an acid pH, ~ (b) thereafter passing through the resin becl a second liquid having an alkaline~pH value, said second !`
.' ::
~ ~ ,, , _ , _ ... .... . . . . ..
.. .. . . . .. .. . .. . . . .
103856Z ; ~ ;~
liquid containing dissolved solute which becomes bound to said resin, and ~c) eluting the bound solute from the resin bed by passing a third liquid through the resin bed, we provide the improvement comprising minimizing channel formation in the resin bed and thereby increasing the exchange capacity of said resin bed by pa3sing through the resin bed during the time when said second liquid is in contact therewith, on more than one occasion in a batchwise 10 manner a fourth liquid having an acid pH value which is sufficiently different from the pH value of said second liquid so as to lower the pH of the li~uid phase in which the resin i~ located on each occasion a batch of fourth liquid is passed through the resin bed.
The process of the~present invention can be used in association with and under all of the conditions of the pr~ocess described in our Canadian Patent ~o. 987459 issued~April 20th : - .
1976. Canadian Patent No. 987459 corresponds to our Swedish ' pat~nt ~o. 345085 which was open to public inspection in March 20 1~73.
One of the most polluted of the various effluents that arise in the paper making process is the effluent arising from a post chlorination alkali extraction stage in the tradiional bleaching of woodpulp, this.being a very dark brown 25 liquid containing lignin degradation produots and other organic pollutants.. The decoLouration of this effluent prior to discharge is very important and the present inven~ion is particularly designed to treat such effluents although it can equally be used~in conjunction wit~ the decolouration of 30 other effluents arlsing in the paper m~king process.
;' ~ ' ' ' ~)3856Z ` : ~
~ he resins used in the process of our Swedish patent No 345085 are particulate phenolic anion exchange resins having pendant groups such as DUOLITE ~ A4-F, A-6, ~ A-7, S-30 and S-37 which are marketed by Diamond Shamrock Chemical Co. of California, U.S.A. and the same resins can be used in the process of this invention.
It is desirable to activate the resin by treatment with aqueous acid prior to contacting the resin with the effluent. ~his aqueous acid may be sulphuric acid or an aqueous solution of SO2. It is convenient to use the same type of acidic solution to activate the resin prior to decolouration of the effluent and to treat the resin batchwise during the decolouration of the effluent in accordance ;~
with the present invention.
According to this invention, the resin is contacted with the aqueous acid on two or more occasions in a ba~chwise man~er during the decolouration of the effluent, that is to say, after activation of the resin but before elution of t~e resin. `;
The following Examples are given to contrast the ..
ability of the resin to decolour effluent when used in accord~
ance with the present invention and when used in accordance with the process of our Swedish patent No. 34S085.
In both Examples a column having an inside diameter of 3.25 m, was filled with a DUOLI~E A-6, a weakly alkaline phenolic anlon exchange resln having pendant amine groups on the phenolic structure.
, .
EX~PLE 1 Process accordinq to Swedish patent No. 34_085 In this run, the ion exchange resin was activated ~ ;~
' :
;
f ` . 9,03~5~i2 ~ ~
with s40 kg of SO2-water, whereby the liquid phase in the upper, activated parts of the resln bed has a pH of between , '1 and 4 approximately. Thereafter,'a daxk coloured aqueous ' effluent from the first alkaline extraction stage of a ~ .
bleaching plant for sulphate wood pulp haYing a capacity of 300 tons of wood pulp per day, was passed through the ion exchange resin. On entry, the aqueous efEluent had a pH of around 11. During the decolouration the pH of the water leaving'the column was kept under observation. It became apparent that only a few bed volumes of effluent were sufficient for the pH to be'brought down to very low values due to the formation of channels in the ion exchange bed which caused an excess quan- '~
ity of~acid to flow out tofether with the purified water. ;
A further efect was that the purifying ability of the resin ; '~
bed declined very r~pidly. This meant that after only S to 6 bed volumes, the effluent retained an unacceptable coluur because of the high content of~lignin degradation products s~ill contained in the e~fluent. ~ Line ~o~ 1 in the Figure ~ "
in the accompanying drawing shows the variation in pH of the treated effluent during thi~ run. In all, 12 bed volumes of ' effluent were treated and only for the initial S or 6 of these an acceptable colour reduction achieved.
In this run,~the same quality of the same ion exchange resin was activated with SO2-water having the s~me concentration as that used in Example 1. 400 kg of SO2-water were used for this purpose. During the effluent decolouration phase of the proce~ a further 200 kg of the 5O2-water, in two batches each o~ 100 kg, was brought into contact with the .
- ~ .
... . . . . . .
.
;~03~5~2 resin bed, the pH of the treated aqueous effluent was measured, but it was no longer possible to detect such low pH-values .as in the first run. This indicates that no formation of channels in the bed of ion exchange resin was occuring and as many as 16 bed volumes of aqueous effl.uent could now be ..
treated with an acceptable degree of colour reduction, being . obtained in each bed volumer This pH of the treated aqueous ;~
effluent in each bed volume is shown on line ~o. 2 on the .
Figure-O
Similar results to those described above were .~
achieved using sulfuric acid as the activation agent and as ..
the addltive agent during the decolouration process.
~ ' . . ....
- ~
~ ,.
, . .
, . ::
. .
! . :
'~;
- ~:'.`. .
: .:~ ~. ,' ' - 6 ~
The present invention relates to a method of reducing the content of pollutants which are lignin or lignin ~ ;
degradation products in the aqueous eff:Luent from forest . :
industries working with cellulose conta:Lning produ~cts. The method is primarily applicable to the treatment of chemical pulp~
mill effluent, e.g. bleached plant waste liquor from such mills but can also be used to treat other effluents $~ containing lignin degradation products, such as screening plant '~ effluent, e.g. back water from su}phite screening plants~
, 10 alkaline condensates etc In our Canadian Patent ~o. 987459 issued April 20th .~:
~! 1976 we describe and claim a method of reducing the content l of lignin degradation products in the aqueous ef~luent from forest and other industries working with cellulose containing I5 products which comprises bringlng the effluent into contact~
with a porous and granular phenollc resln which~will~absorb~
:3~ the lignin and lignln derivatlves~from the effluent~ séparating ;~
an effluent of reduced lignin and~lignin derivative~content and recirculatlng lt or discharging it to an outflow;~and~
eluting the resin to ;recover the lignin and llgnin;derivatives ~ for disposal.
J~ In the operation of this method on full plant`~scale,~
t~is desirable to~be~able to~maximise the num~er~of bed valumes~
of~effluent that;~can be treated~to~give~adequate~decolouratlon ;~
; 25~ ~of the~effluent~before lt ls necessary to elute the resln. ;
We~have now found~that one reason~for the falling~off in the ~l~ ability of the~resin to decolour the effluent is that the volume of the~resin Ls~influenced by the pH of its~environmént and ~ -;~ ; that changes in environmental~pH bring about chang~s in ~the ~: : ~: ` :: `
~ 30 resin volume and this in turn may bring about the~formation of _ _ .......... _ ,_~_~ . ~ . .... . . . .. .
channels in the resin bed which reduces the ability o~ the re~in to decolour the effluent. The present invention provides ; ;
a method of ~ubstantially eliminating this problem.
In one aspect of the present invention, in a method of reducing the content of organic pollutants which are lignin or lignin degradation products in an aqueous effluent solution ~ ~
from forest industries working with cellulose containing`
products which comprises passing the aqueous effluent solution through a bed of a porous and granular phenolic resin which will take up the pollutants from the effluent, said resin being ;
of a type whose volume changes with change of the pH of the liquid phase in which the resin is located, separating an effluent of reduced pollutant content and eluting the~resin to remove the pollutants for disposal and regenerate the resin for i further use, we provide the improvement which comprises minimising volume changes inthe resin bed by batchwise addikion of an aqueous acid solution to the resin bed so that the pH of the li~uid phase in which the resin is located is~repeatedly lowered during treatment o~ the effluent whereby formation of channels in the resin bed is ubstantially eliminated. ~` ;
In another aspect of the present invention ln a method~ ;
of binding solute which is lignin or lignin degradation products ~
, .
dis~olved in an aqueous effluent solution, said methocl comprising~
~a) preparing a bed of a phenolic resin capable of `
binding said solute, said resin bed being a bed which changes its volume with change of pH of the liquid phase in which the resin is located, by passing through the resin bed an acidic first liquid having an acid pH, ~ (b) thereafter passing through the resin becl a second liquid having an alkaline~pH value, said second !`
.' ::
~ ~ ,, , _ , _ ... .... . . . . ..
.. .. . . . .. .. . .. . . . .
103856Z ; ~ ;~
liquid containing dissolved solute which becomes bound to said resin, and ~c) eluting the bound solute from the resin bed by passing a third liquid through the resin bed, we provide the improvement comprising minimizing channel formation in the resin bed and thereby increasing the exchange capacity of said resin bed by pa3sing through the resin bed during the time when said second liquid is in contact therewith, on more than one occasion in a batchwise 10 manner a fourth liquid having an acid pH value which is sufficiently different from the pH value of said second liquid so as to lower the pH of the li~uid phase in which the resin i~ located on each occasion a batch of fourth liquid is passed through the resin bed.
The process of the~present invention can be used in association with and under all of the conditions of the pr~ocess described in our Canadian Patent ~o. 987459 issued~April 20th : - .
1976. Canadian Patent No. 987459 corresponds to our Swedish ' pat~nt ~o. 345085 which was open to public inspection in March 20 1~73.
One of the most polluted of the various effluents that arise in the paper making process is the effluent arising from a post chlorination alkali extraction stage in the tradiional bleaching of woodpulp, this.being a very dark brown 25 liquid containing lignin degradation produots and other organic pollutants.. The decoLouration of this effluent prior to discharge is very important and the present inven~ion is particularly designed to treat such effluents although it can equally be used~in conjunction wit~ the decolouration of 30 other effluents arlsing in the paper m~king process.
;' ~ ' ' ' ~)3856Z ` : ~
~ he resins used in the process of our Swedish patent No 345085 are particulate phenolic anion exchange resins having pendant groups such as DUOLITE ~ A4-F, A-6, ~ A-7, S-30 and S-37 which are marketed by Diamond Shamrock Chemical Co. of California, U.S.A. and the same resins can be used in the process of this invention.
It is desirable to activate the resin by treatment with aqueous acid prior to contacting the resin with the effluent. ~his aqueous acid may be sulphuric acid or an aqueous solution of SO2. It is convenient to use the same type of acidic solution to activate the resin prior to decolouration of the effluent and to treat the resin batchwise during the decolouration of the effluent in accordance ;~
with the present invention.
According to this invention, the resin is contacted with the aqueous acid on two or more occasions in a ba~chwise man~er during the decolouration of the effluent, that is to say, after activation of the resin but before elution of t~e resin. `;
The following Examples are given to contrast the ..
ability of the resin to decolour effluent when used in accord~
ance with the present invention and when used in accordance with the process of our Swedish patent No. 34S085.
In both Examples a column having an inside diameter of 3.25 m, was filled with a DUOLI~E A-6, a weakly alkaline phenolic anlon exchange resln having pendant amine groups on the phenolic structure.
, .
EX~PLE 1 Process accordinq to Swedish patent No. 34_085 In this run, the ion exchange resin was activated ~ ;~
' :
;
f ` . 9,03~5~i2 ~ ~
with s40 kg of SO2-water, whereby the liquid phase in the upper, activated parts of the resln bed has a pH of between , '1 and 4 approximately. Thereafter,'a daxk coloured aqueous ' effluent from the first alkaline extraction stage of a ~ .
bleaching plant for sulphate wood pulp haYing a capacity of 300 tons of wood pulp per day, was passed through the ion exchange resin. On entry, the aqueous efEluent had a pH of around 11. During the decolouration the pH of the water leaving'the column was kept under observation. It became apparent that only a few bed volumes of effluent were sufficient for the pH to be'brought down to very low values due to the formation of channels in the ion exchange bed which caused an excess quan- '~
ity of~acid to flow out tofether with the purified water. ;
A further efect was that the purifying ability of the resin ; '~
bed declined very r~pidly. This meant that after only S to 6 bed volumes, the effluent retained an unacceptable coluur because of the high content of~lignin degradation products s~ill contained in the e~fluent. ~ Line ~o~ 1 in the Figure ~ "
in the accompanying drawing shows the variation in pH of the treated effluent during thi~ run. In all, 12 bed volumes of ' effluent were treated and only for the initial S or 6 of these an acceptable colour reduction achieved.
In this run,~the same quality of the same ion exchange resin was activated with SO2-water having the s~me concentration as that used in Example 1. 400 kg of SO2-water were used for this purpose. During the effluent decolouration phase of the proce~ a further 200 kg of the 5O2-water, in two batches each o~ 100 kg, was brought into contact with the .
- ~ .
... . . . . . .
.
;~03~5~2 resin bed, the pH of the treated aqueous effluent was measured, but it was no longer possible to detect such low pH-values .as in the first run. This indicates that no formation of channels in the bed of ion exchange resin was occuring and as many as 16 bed volumes of aqueous effl.uent could now be ..
treated with an acceptable degree of colour reduction, being . obtained in each bed volumer This pH of the treated aqueous ;~
effluent in each bed volume is shown on line ~o. 2 on the .
Figure-O
Similar results to those described above were .~
achieved using sulfuric acid as the activation agent and as ..
the addltive agent during the decolouration process.
~ ' . . ....
- ~
~ ,.
, . .
, . ::
. .
! . :
'~;
- ~:'.`. .
: .:~ ~. ,' ' - 6 ~
Claims (9)
1. In a method of reducing the content of organic pollutants which are lignin or lignin degradation products in an aqueous effluent solution from forest industries working with cellulose containing products which comprises passing the aqueous effluent solution through a bed of a porous and granular phenolic resin which will take up the pollutants from the effluent, said resin being of a type whose volume changes with change of the pH of the liquid phase in which the resin is located, separating an effluent of reduced pollutant content and eluting the resin to remove the pollutants for disposal and regenerate the resin for further use, the improvement which comprises minimising volume changes in the resin bed by batchwise addition of an aqueous acid solution to the resin bed so that the pH of the liquid phase in which the resin is located is repeatedly lowered during treatment of the effluent whereby formation of channels in the resin bed is substantially eliminated.
2. In a method of binding solute which is lignin or lignin degradation products dissolved in an aqueous effluent solution, said method comprising.
(a) preparing a bed of a phenolic resin capable of binding said solute, said resin bed being a bed which changes its volume with change of pH of the liquid phase in which the resin is located, by passing through the resin bed an acidic first liquid having an acid pH, (b) thereafter passing through the resin bed a second liquid having an alkaline pH value, said second liquid containing dissolved solute which becomes bound to said resin, and (c) eluting the bound solute from the resin bed by passing a third liquid through the resin bed, the improvement comprising minimizing channel formation in the resin bed and thereby increasing the exchange capacity of said resin bed by passing through the resin bed during the time when said second liquid is in contact therewith, on more than one occasion in a batchwise manner a fourth liquid having an acid pH value which is sufficiently different from the pH value of said second liquid so as to lower the pH of the liquid phase in which the resin is located on each occasion a batch of fourth liquid is passed through the resin bed.
(a) preparing a bed of a phenolic resin capable of binding said solute, said resin bed being a bed which changes its volume with change of pH of the liquid phase in which the resin is located, by passing through the resin bed an acidic first liquid having an acid pH, (b) thereafter passing through the resin bed a second liquid having an alkaline pH value, said second liquid containing dissolved solute which becomes bound to said resin, and (c) eluting the bound solute from the resin bed by passing a third liquid through the resin bed, the improvement comprising minimizing channel formation in the resin bed and thereby increasing the exchange capacity of said resin bed by passing through the resin bed during the time when said second liquid is in contact therewith, on more than one occasion in a batchwise manner a fourth liquid having an acid pH value which is sufficiently different from the pH value of said second liquid so as to lower the pH of the liquid phase in which the resin is located on each occasion a batch of fourth liquid is passed through the resin bed.
3. A method according to claim 2 wherein the first liquid and the fourth liquid are the same.
4. A method according to claim 1 wherein the resin is activated, prior to contact with the effluent, by treatment with aqueous acid and the aqueous acid is a solution of the same acid used to treat the resin during removal of the pollutants from the effluent.
5. A method according to claim 1 or 2 wherein the resin is a phenolic anion exchanger having pendant amino groups.
6. A method according to claim 1 or 2 wherein the aqueous effluent solution is a post-chlorination alkali extraction effluent from paper pulp bleaching.
7. A method according to claim 1 or 2 wherein the acid introduced batchwise into the resin bed is sulphuric acid or an aqueous solution of SO2.
8. A method according to claim 1 or 2 wherein the aqueous effluent solution has a pH of at least 8 prior to contact with the resin.
9. Process according to claim 1 or 2 wherein the resin bed is eluted with sodium hydroxide.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7308281A SE379808B (en) | 1973-06-13 | 1973-06-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1038562A true CA1038562A (en) | 1978-09-19 |
Family
ID=20317744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA202,221A Expired CA1038562A (en) | 1973-06-13 | 1974-06-12 | Method of purifying effluents from forest industries |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5069853A (en) |
| BR (1) | BR7404828D0 (en) |
| CA (1) | CA1038562A (en) |
| FI (1) | FI54621C (en) |
| FR (1) | FR2233289A1 (en) |
| NO (1) | NO742092L (en) |
| SE (1) | SE379808B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109929215B (en) * | 2019-03-25 | 2021-03-30 | 南京大学 | High-mechanical-strength anion exchange resin with phenolic aldehyde-polyacrylic acid series interpenetrating structure and preparation method thereof |
-
1973
- 1973-06-13 SE SE7308281A patent/SE379808B/xx unknown
-
1974
- 1974-05-23 FI FI1585/74A patent/FI54621C/en active
- 1974-06-10 FR FR7419898A patent/FR2233289A1/en active Granted
- 1974-06-10 NO NO742092A patent/NO742092L/no unknown
- 1974-06-12 BR BR4828/74A patent/BR7404828D0/en unknown
- 1974-06-12 CA CA202,221A patent/CA1038562A/en not_active Expired
- 1974-06-12 JP JP49066969A patent/JPS5069853A/ja active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| FI54621C (en) | 1979-01-10 |
| NO742092L (en) | 1975-01-06 |
| FR2233289B1 (en) | 1977-03-11 |
| BR7404828D0 (en) | 1975-09-30 |
| SE379808B (en) | 1975-10-20 |
| FI158574A (en) | 1974-12-14 |
| FR2233289A1 (en) | 1975-01-10 |
| FI54621B (en) | 1978-09-29 |
| JPS5069853A (en) | 1975-06-10 |
| SE7308281L (en) | 1974-12-16 |
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