|Title of Invention||
"AN IMPROVED PROCESS FOR THE SEPARATION OF LIGNIN FROM BLACK LIQUOR WASTE OF PAPER MILLS".
|Abstract||An improved process for the separation of lignin from black liquor waste of paper mills by treating the black liquor under stirring with a mixture of calcium chloride, alum and common earth for a period of at least 5 minutes, separating the lignin by known methods|
|Full Text||This invention relates to an improved process for the separation of lignin from black liquor waste of paper mills. More particularly it relates to an improved method for separation of lignin and colouring matter from black liquor effluent from paper mill waste.
According to the widely accepted concept lignin may be defined as an amorphous polyphenolic material arising from an enzyme mediated dehydrogenative polymerization of three phenyIpropanoid monomers, of e.g. coniferyl, sinapyl and p—coumaryl alcohols. Lignin (from the latin lignum, wood) is after cellulose, the principal. constituent of woody structure of higher plants in part deposited in the xylem cell walls, in part located in the intercellular spaces.
The sulfite waste liquors from paper mills contain upto 3 to 6*/. lignin which is not easily biodegradable. This lignin may act as a source of vanillin, syringic aldehyde, can be used as extender for phenolic plastics as well as to strengthen the rubber, as oil mud additive to stabilize asphalt, as emulsions to precipitate proteins.
Lignin also can be converted to pure low molecular weight chemicals; it may serve as an important feedstock for the chemical industry. At present only vanillin and dimethyl sulfide are produced commercially, taut economically competitive processes for conversion to phenolic and aromatic chemicals are real possibilities.
Until the past 2--3 decades or so, large amounts of lignin were discarded into streams and waterways as dilute aqueous solutions which is not tolerated now and almost all waste streams containing lignin are concentrated and burned.
In order to conform to environmental quality guidelines, a number of primary and secondary treatment systems to control effluents are installed, treatment comprises clarifiers to remove 85—100 wt. 'A of solids such as clarifiers in first treatment and lagoons aerated or otherwise, trickling filters, modified biological systems, charcoal treatment etc. to remove as 90—95*/. of BOD, most solids, most of the toxicity except very little colour. Ultra filtrations also has been tried and found futile to remove total dissolved solid s comp1ete1y.
The pulp and paper industry uses large amounts of water which is recycled and reused resulting in temperature rise and dissolution of more solids in water enhancing problems e.g. corrosion , slime and other deposits. Directly ar indirectly all of these viz. BOD color and toxicity may effect aquatic life.
Total dissolved solids are removed and used as energy source in fuel. Biomethanation has also been attempted.Al1 these do not meet the standards of pollution control. Therefore it become* very essential to remove color, total dissolved solids with negligible quantity of BOD and COD.
in the prior art following methods are used for the separation of lignin from black liquor in paper industry. Several methods hitherto used are described in brief hereinbelow :
This is mainly useful to minimise industrial pollution due to the black liquor.
PURIFICATION OF WASTE WATERS FROM INSTALLATIONS FOR BLEACHING SULFATE PAPER
Udeleholms A.B. Fr. Demande 2,202,043 03 May 1974. Swed Appl. 12772/72 04 Oct. 1972 CA 82:34833 g (1975).
The lignin and other organic matter are mostly precipitated from waste water by addition of mineral acid and by filtration. The filtered waste water is treated with feebly alkaline ion exchange resin activated with acid and then resin is eluted with alkali to remove adsorbed lignin. The eluate together with solution of original precipitate in alkali are recycled to the sulfate pulp process, preferably by burning in the black liquor recovery process.
DESULFURIZATION OF WASTE GAS WITH PULP WASTE LIQUOR
Suyama A; Hayashi, H [Mitsubishi Kausha Ltd. Toyo Tokushi Kogyo K.K.3 Jap. Kokai 76, 20, 089 17 Feb. 1976. CA 85:67527a (1976) Fibre-free black liquor is used for waste gas desulfurization and lignin in waste liquor is precipitated as a lignin sulfate. The fibre is removed by boiling. Thus 1100 ppm SO containing
diesel. oil boiler flue gas was desulfurized with bailed black liquor (pH 12) to desul. furize 93%.. The spent liquor was air
oxidised and coagulant was added to precipitate lignin and others.
RECOVERY OF SODIUM HYDROXIDE AND BLACK LIQUOR FROM CELLULOSE MANUFACTURE.
Torras Hostench S.A. Belg. 861 , 585 31 March 1978. Span Appl.
461, 364 04 Aug. 1977. CA 89: 61292 (1978).
An improved process for title recovery as compared to Spanish
patent No.29, 158 comprises carbonation of spent liquor Cprecon-
centrated to 40*/ from 10-15%.II from treatment of pulp by bubbling
CO through a stream of spent liquor in a counter current system
from bottom to the top of the liquor at 70-85 C and 0.5 kg/cm
and treating the resulting si 1ica-1ignin precipitate with 0.03 N
NaOH to redissolve the lignin for recycling to carbonated black
liquor before further concentrating by evaporating.
RECOVERY OF INORGANIC COMPOUNDS FROM KRAFT PULPING BLACK LIQUORS
Domtar Inc. Jpn. Kokai. Tokkyo Koho 58 36292 (83 36292) 03 Marc. 1985. Appl. 382387 23 July 1981. CA 99: 89814 h (1983).
Na compounds from kraft pulping black liquors are recovered by
first acidifying the cool liquor with acids containing H SO
to precipitate more than 4.5 to coagutae lignin. Heating the
o liquor at about 60 , filtering the liquor and finally cooling
the filtrate to form crystallized Na SO for recycling. Thus
o kraft pulping black liquor (solids ~50%. ) was cooled to ""40
acidified with H SO to give recyclable Na SO .
2 4 2 4
KRAFT OVERLOAD RECOVERY
Beaupre Marc F.; Cambran Emile A Cambron Emily T. US 4 470 876 11 Bept P 984 Appl. 400 960 22nd July 1982 CA 101 : 194014 3 (1984).
A process in which a portion of black liquor I.BL11 is concentrat-
o ed to atleast 4(3*/, coaled 5-50 acidified with H SO containing
Na SO from C10 preparation to pH 4.5, heated to ""60
2 4 2
to separate lignin 1:9005-53-23. Neutralized with NaOH treated
with 1st portion of BL and burnt in furnace to recover inorgan
ics, was described for augmenting the recovery capacity of the
SEPARATION OF ORGANIC ACIDS FROM KRAFT BLACK LIQUORS USINQ MEMBRANES
Bowe J. CUS Deptt of Agriculture] US Pat. Appl. US 725,720 20
Dec. 1985. Appl. 22 Apr. 1985. CA 104; 151 147 v E19861.
Avail NTIS Order Mo. Pat. Appl. -6-725, 720. A method wag described to recover low mol. wt. aliphatic organic acids from Kraft Black Liquor by ultra centrifugation (UC) of liquor, fallowed by e 1 ectrod i alysis TIE! of UC permeate treating deionate from E with acid to precipitate lignin and electrolytic H 0
splitting of resulting solution.
REMOVAL OF LIQNIN FROM ALKALINE WASTE PULPING LIQUORS
Ishikawa H; Kade K. COji Paper Co.Ltd!. Jpn. Kokai Tokkyo K.oho JP 62 90389 [87 90 38911 24th Apr. 1987 85 226 870 14 Oct. 1985. CA 107 : 79 808 d [1987I1.
The title removal involved colloidising the solution lignin
fallowed by ultra filtration. Thus beech chips were cooked at
o effective alkali 14'/. sulfidity 25'/. liquor ratio 4 and 165 . Tha
resulting black liquor was filtered, adjusted to pH 11, 10 and 9
with with CO and ultra filtered to give de 1 ign i f icat ion 89'/.,
94*/. and 97*/. respectively.
MANUFACTURE OF METHYLOLATED LIGNIN FROM BLACK KRAFT LIQUOR RESIDUES
Dilling Peter [West Vac.o Carpi US 4, 764,5971.6 Aug. 1988 Appl.
61 460 15 Jun 1987 CA 109:212612 v C1988 1.
Methylolated lignin til is manufactured from black Kraft liquor residues by initially oxidizing black kraft liquor containing [I]1 and salt in situ methylolat ion of [I] with an aldehyde followed by lowering the pH of the black kraft liquor residue to precipitate methylolated [i] and finally recovering the precipitated methylolated t. 11 from black liquor residue. Thus a black kraft residue tpH 131 was oxidized with air until the Na B
content was 1%. and then stirred with 31b/mole HCHO/1000 lb I at
70 for 2h. The black, liquor containing methylolated I was
acidified with HSQ to pH „ The methylolated I. was coagulated
4 4 a at 85 , filtered, washed with water. The methylolated slurry
was then treated with triethanolamine to pH 7 and then sulfonat-
o ed with SO at 205 F for 12h to give sulfame thy1ated. I amine
salt useful as dispersant for azodyes.
RECOVERY OF SOLIDS FROM BLACK LIQUORS
Caperos, S.A; Span ES 2, 006, 964 16 May 1989 Appl. 8,801,697 27 May 1988. CA 114; 26042 n C19913.
Solids in black liquors are recovered as precipitate by mixing 1 part black liquor with 0.1 - 1.0 part reactive precipitating agents and separating the precipitate. Thus 1000 cm black liquor of E. globulus was mixed with 1000 cm saturated of solution of CaCl in E-ItOH to form precipitate which was separated
with centrifuge and washed with 1:1 EtOH- water to give ppt. 134, organic components 105 lignin 53 and pentosans 8g with 85% yield.
AERDINB PROCESS OF PAPER BLACK LIQUOR WITH SULFUR DIOXIDE.
Sun, L; Xu, L; Mu, H et al [Chinese Academy of Sciences, environment estimating department]. Faming Zhuangli Shenging Bana-kai Shouming Shu. CN 1,050 064 20 Mar. 1991 Appl. 89 106 694 04 Sept.1989 CA 115: 282382 t L1991D.
The title process is described by heating black liquor with SO
to separate lignin and recover Na sulfite from the remaining acidic solution.
TREATMENT OF BLACK PULP LIQUOR BY COACERVATION AND PRECIPITATION
Zhang M; Faming Z; Shenging G; Shouming S. CN 1, 057 079. 18 Dec. 1991 Appl. 90, 104, 181 5 Jun 1990 CA 117: 173 646 c .
Black pulping liquor is treated by adding solid CaCl or aq.
solution containing CaCl [2-5 g/1.00 mL] to black pulping liq-
uor, coagulating and precipitating to remove lignin and recovered diluted NaOH solution. Thus 17.5 g lignin and 6 g/L NaOH aq. solution were recovered by adding 3g CaCl in 100 ml. sulfate
black liquor Cfrom preparing of pine pulp], precipitating and fi11ration.
AGGLUTINANT FOR RECOVERING ALKALI IN PAPER MAKING INDUSTRY AND ITS PREPARATION
Wang, W, Faming, Z; Bhenging G. Bhouming S. CN 1,094,106 '2h Oct. 1994. Appl. 94, 104, 572 05 May 1994. CA 1.23:343940 n
The agglutinant for recovering alkali and lignin from black liquor of a paper waste comprises a mixture of a waste Al, an acid mixture, a polymer selected from polys, (dimethy1aminometh-yl) acrylamide3 polyaci'y 1 amde derives, poly vinyl sulfonate, and Na aglinate a coal dust, a Mg based inorganics salt and lime.
In hitherto known processes main drawbacks are the use of acidic media which involve problems of corrosion, filtration due to collidal particles and incomplete removal of organic as well as inorganic matter in the effluent water, colored effluent water due to organics mainly lignin.
There is continuing interest on the development of new improved process for separation of lignin, organic matters, inorganic compound's from the black liquor produced in the paper industry.
It is known fact that lignin in effluents is not biodegradable and hence disposal problems in the environment.
The main object of the present invention is to provide an improved process for the tratment of black liquor waste from paper mills more particularly the separation of lignin, organic and inorganic coloured matters from black liquor waste produced in the processing of paper mill to the environment standards for treated effluents.
Another object of the present invention is to provide a process which does not use acidic conditions for the treatment of effulents, thereby reducing the hazards of corrosion and other problems mentioned earlier.
Accordingly the present invention provides an improved process for the separation of lignin from black liquor waste of paper mills which comprises a process for the separation of lignin from black liquor waste of paper mills, characterized in that treating the black liquor under stirring with a mixture of calcium chloride, alum and common earth at a ratio ranges from 0.1-1% to 0.1-1% to 0.1-1% for a period of atleast 5 minutes, separating the lignin by known methods.In an embodiment of the present invention 0.1 to 1 wt */♦ of commercial calcium chloride, 0.1 to 1 wt% commercial alum and 0.1 to 1 wt 'A of common earth with respect to effluent.
The separation of lignin may be effected by known methods such
f i 11 r a t ian, dec an t a t i on.
In another embodiment of the present invention the ion exchange
resin used may be selected from anion/cat ion exchange resin
wh i ch are commerciaI1y available.
In a feature of the present invention the treated effluent was found to be passing BOD, COD and all other parameters of effluent treated water required by environmental agencies.
In another feature of the present invention all operations in this process are done at room temperature without the use of mineral acid etc. to make all the effluents free from organics and inorganics, the treated water can be recycled to the process. The resins used in the process can be regenerated with known methods.
The invention is described hereinbelow with reference to follow
ing examples which are illustrative only and should not be
construed to limit the scope of the present invention in any
500 ml black pulp liquor industrial effluent containing 3X lignin was treated with calcium chloride (3 g) alum (3 g) and earth (3 g) under stirring for 0.5 h and filtered without suction to remove lignin. The filtrate was adjusted to pH ~8 by adding 10%. NaOH solution (0.6 ml) and treated with regenerated washed Indion resin to bring pH 2-3 with stirring (10 ml). This was repeated once again finally the solution was passed through activated charcoal column with light suction to give colorless water with no organic matter.
Initial COD was 1,20000 which was brought down to 230 mgs/lit. BOD was found 25.
500 ml black pulp liquor industrial effluent containing 3% lignin was treated with calcium chloride (3 g) alum (1.5 g) and earth (1.5 g) under stirring for 0.5 h and filtered without suction to remove lignin. The pH of filtrate was adjusted to about 8 by adding 10'/. NaOH solution (0.5 ml) and treated with regenerated washed Indion resin with stirring to bring the pH of solution to ~2-3 (10 ml). This was then filtered and the filtrate was passed through Tulsan resin column (80 g) when the pH of the eluate changed to neutral. This was then passed through charcoal column to remove colour, when a clear water was obtained with no organic or inorganic matter.
COD which was 1,30000 initially reduced to 200 mg/lit and BOD also reduced to 20.
500 ml black liquor industrial effluent was treated with calcium chloride (1 g) alum (1 g) and earth (1 g) with stirring for 15 min. A muck settled (~100 ml) after about 4 h, supernatant clean solution was decanted and the liqnin sludge was filtered through fluted filter paper. Decanted clear solution and the filtrate were combined and treated with Indian (10 ml regenerated and washed) resin with stirring and filtered through fluted filter paper. The filtrate was then passed through activated charcoal column (5 g) when clear water was obtained with no organic or inorganic: matter.
Initial COD was 80,000 which was reduced to 180 ml/lit BOD also was reduced to 27.
1. An improved process for the separation of lignin from black liquor waste of paper mills which comprises a process for the separation of lignin from black liquor waste of paper mills, characterized in that treating the black liquor under stirring with a mixture of calcium chloride, alum and common earth at a ratio ranges from 0.1-1% to 0.1-1% to 0.1-1% for a period of atleast 5 minutes, separating the lignin by known methods.
2. An improved process for the separation of lignin from black liquor waste of paper mills
|Indian Patent Application Number||796/DEL/1997|
|PG Journal Number||31/2009|
|Date of Filing||27-Mar-1997|
|Name of Patentee||COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH|
|Applicant Address||RAFI MARG, NEW DELHI-110 001, INDIA.|
|PCT International Classification Number||D21C 11/04|
|PCT International Application Number||N/A|
|PCT International Filing date|