PULP & PAPER INDUSTRY :

In India, there are 36 large and 314 small scale paper mills. Large paper mills have individual production capacity greater than 24,000 TPA (65 tpd) and almost all have got soda recovery units. These mills mostly use bamboo/hardwood as raw material. Among the small scale mills, 100 units are agro-residue based and the rests are waste paper based or purchased pulp based or a Combination of these two.

Large Scale Units
All the large scale pulp & paper industries have effluent treatment facilities, they have installed the chemical recovery system and are recovering the valuable chemicals from the black liquor. However, the following are the problems still unsolved.

Colour
Colour problem exists with this category of industry despite adequate treatment facilities. The problem of colour could be overcome by changing over to cleaner processes, i.e. the use of oxygen/hydrogen peroxide bleaching in place of conventional Hypo-chlorite bleaching.

Quantum of effluent discharge
The standards in terms of effluent volumes per tonne of paper (Annexure-l) are not usually met by majority of the paper mills. The implementation of inplant control measures is necessary to bring down the fresh water poses consumption as well as the quantity of the effluent discharged.

Total Organic Chloride (TOCI)
 This pollutant contributes to toxicity due to organo-chlorine compounds in the effluent arising out of use of chlorine in bleaching process. Therefore, compliance of standards of TOCI could be possible, only if industry adopts other methods of bleaching, such as oxygen bleaching or peroxide bleaching As such it will require process change.

There are a considerable number of large scale pulp & paper industries which are using their treated effluent for irrigation in captive two. plantation. However, its impact on soil quality is yet to be studied scientifically.

Small Scale Units
the principal raw ma erla or small-scale pulp & paper Industry are agricultural residues (baggasse, rice straw, wheats straw, elephanta grass, etc.) and waste paper. The problems of pollution are more predominent in small scale agro-based units due to non-adoption of chemical recovery process in view of high cost.

The BOD standard of 30 mg/1 for discharge on inland surface water & 100 mg/1 for land disposal has been notified under the Environment (Protection) Rules. The industry is advised to segregate the black liquor and store it separately and treat the rest of the effluent. The Quantum or emuent discharge stored black liquor, is required to be discharged during the rainy season only when sufficient dilution is available.

Problems of chemical recovery process
The presence of silica in black liquor a problem in the development of suitable chemical recovery process for agro-based paper industries. Suitable economically viable Total Organic Chloride (TOCI) chemical recovery process is yet to be developed to suit the requirement of small-scale pulp & paper industries

In the mills, where no chemical recovery is adopted, the discharge of black liquor in effluent stream makes it difficult to treat, The presence of high contents of sodium even after treatment, makes the effluent unfit for irrigation and forestry use.

Status or R&D on Cleaner Technologies in Pulp & Paper Industries
Several institutions and industries are engaged in developing suitable technology and process to reduce/ elimjnate the pollutants in the of paper production. Following are some of the findings of the research work carried out so far.

 M/s Amrit Papers ltd.
This industry has implemented the chemical recovery process successfully on a pilot scale which takes care of the silica problem, Efforts are on to implement this process on a commercia scale.

Central Pulp & Paper Research Institute
 The institute is doing research on ferrite chemical recovery process for agricultural residue-based pulping. Success has been made to adopt the process on full scale for economic implementation on a commercial basis.

 M/s Pudumjee Pulp & Paper Mills
This industry has deve~oped a pulping Mother Pulping process based on solvent (mixture of ethanol and water) for agricultural residue (baggas,se) as raw material, It has been successfully trled on pilot scale, The solvent used in pulping is recovered from the waste by distillation process. Negligible quantity of effluent is generated and lignin is recovered as a by- product. Pulping plant of 50 tpd is proposed to be installed based on this process.

 Common Chemical Recovery (CCR)
The chemical recovery is economically viable in case of large mills, but it is not so in case of small scale mills on an individual basis. However, if it is tried collectively the recovery may become economically viable.

Common Chemical Recovery (CCR) Plant ..may be the solution for the mills located at one place in a cluster. In this system, black liquor from the small agro-based paper mills at any particular area can be collected and brought to one place for the common chemical recovery . The cluster of paper units may form all Association for the installation and operation the Common Chemical Recovery Plant. In, Muzaffarnagar, U.P. there are about 30 small agro based pulp and paper mills, and this may M/s. Amrit Papers Itd. be a suitable place for implementing the idea of CCR.

 The highlights of CCR process are laid down as follows :

  1. Economic benefit by way of chemical (Caustic Soda) recovery
  2. Energy saving
  3. Less Pollution laod (in both quantity and quality)
  4. Less cost of waste water treatment

CPCB is studying the techno-. feasibility of the system

Mother Pulping
Mother Pulping could be one of the solutions for small agro-based units in clusters, The mother pulping means setting up of a common (big) pulping plant and distribution of pulp after separation of black liquor among the. mills for further washing and paper manufacturing. Due to the large size of the mother pulping on this process. plant, the chemical recovery plant will be techno economically viable, The installation and Common Chemical Recovery (CCR) operation of the mother pulping plant can be done by the association of the paper units, This will help in lesser pollution and treatment at lower cost along with the recovery of valuable chemicals.

Solvent based cleaner pulping process

Alkaline Sulphite Anthraquinon Methanol (ASAM) Pulping
The wood chips are presteamed for 15 minutes before the cooking liquor is added. The typical liquor consists of up to 25% inorganics, calculated as NaoH based on dry wood, where 20% are Na2SO3 and the remaining one added as NaoH or Na2 CO3 or a combination thereof 10 -20% methanol and around 0.1% of anthraquinon (AQ) as a catalyst.

  • The ASAM pulp has very low lignin content, almost no extractives and considerable initial brightness. Chlorine free bleaching is possible.
  • No reduced sulphur compounds are made during the ASAM process and methanol is kept in closed cycle system.
  • ASAM pulp can be bleached to high brightness in Chlorine free sequences and as a result there are no toxic and difficult to degrade organic chlorine compounds in the effluent
  • No poisonous and oxygen consuming element in effluent.
Sulphur and Chlorine free Oxgen - Alkali Cooking Process
  • The process uses oxygen-alkali cooking of chips. The alkaline agents may be caustic soda, sodium carbonate or ammonium hydroxide.
  • It produces sulphur and chlorine free Pulp. The untreated effluent is totally non-toxic.
  • There is a 0.5 TPD Pilot Plant at the Sjas Mill near St. Petersburg, Russia. Semi- Solvent based cleaner pulping process industrial size plant of 35,000 ton per annum is under construction and will be commissioned in Russia.
ALCELL Process (Organosolv, Pulping Process)
  • It uses aqueous ethanol as pulping liquor.
  • Process is odourless and is free from total reduced sulphur and methyl-. mercaptan. Chlorine - Free bleaching is possible.
  • The. bleach plant effluent contain no f dioxins, furans and very low level of AOx.
A demonstration plant of 15 tpd is working and a.commercial scale mill with an appropriate. capacity of 300 tonne/day In planned to be designed.

Oraganocell Pulping
  • The wood chips preheated with a mixture of ethanol/methanol and water followed by their cooking with alkali and anthraquinon.
  • The process produces sulphur-free pulp as well as sulphur -free lignin.
  • It does not involve use of chlorine - compounds in bleaching of pulp hence leaves no TOCI & AOx in effluent
M/s. Bayrische Zellstoff Gmbh at Kelhein Germany is going to adopt Organocell process. - However, a pilot plant has been operated since 1987 in Munchen, Germany without any. objectionable impact on the sorroundings.

Punec Pulping Process
  • Process involves delignification of , lignocellulosic material in the absence of polluting sulphur and chlorine compounds
  • Involves use of ethanol-water mixture as solvent in the presence of catalytic amount of NaOH for a neutral pH
  • Provides a means of recovery of the chemicals used.
  • Recovery of useful byproducts like lignin and hemicellulose
  • It does not c.ause generation of AOx and the process IS free from the total reduced, sulphur.
  • This process is not yet commercialized. It has been tested on pilot scale. M/S, Pudumjee Pulp & Paper Ltd. proposes to set up 50 tpd pulp plant based on - technology in India.
ZONE-WISE INSTALLED CAPACITY FOR MANUFACTURING PAPER AND PAPER BOARD
 
Forest based
Agro based
Others
Total
Zone
No. of Units
I.C.(000'T)
No. of Units
I.C.(000'T)
No. of Units
I.C.(000'T)
No. of Units
I.C.(000'T)
East
13
644
8
101
16
45
37
790
North
3
126
38
347
85
351
126
824
South
10
524
19
239
29
153
58
916
West
3
191
24
287
92
455
119
933
                    (I.C. = Installed Capacity)
PROJECTED RAW MATERIALS REQUIREMENTS FOR PULP & PAPER INDUSTRY
(2000-01 TO 2010 - 11)
S.No.Raw Materials
Quantities in Million Tonnes in the Year
 
1990-91
2000-01
2010-11
1.
Bamboo/Ochlandra reeds
1.36
4.18
6.70
2.
Hardware including eucalyptus
1.77
4.40
7.07
3.
Cereal straws and bagasse
1.20
5.72
9.53
4.
Waste Paper
0.87
1.06
1.87
5.
Market pulp
0.32
0.47
0.72
6.
Others including grasses etc.
0.33
0.27
0.27
Total
5.85
16.10
26.16

Soda Recovery
There are 275 mills of smaller capacity ranging from 1,000 to 20,000 TPA in our country. About 70% of these mills are based on soda chemical pulping of agro-residues and do not have any facility for the recovery of chemicals.non - recovery of chemicals is the largest single factor for crippling the economy of the paper industry based on agro-residues. It is estimated that the small-scale paper industry of about 50 TPD discharges waste soda liquor equivalent to Rs. 30,0 millions and Rs, 3,3 million as thermal energy annually, at the same time releasing pollution load equivalent to a 100 tpd mills equipped with a recovery unit, The energy loss also accounts for 12000 MW per annum at the national level, assuming the energy consumption as 2000 kwh per tonne of caustic production as envisaged by any caustic plant.

 Studies on chemical recovery/cogeneration have established the justification on techno-viablllty , While the benefit to the individual enterprise may be due to substantially improved operative costs, this would make a comulative impact on the economy of the country as a whole. The pollution control laws have made it mandatory to regulate the quality of effluent discharged by the agro-based mills, At present, black liquor generated in pulp mill goes to effluent plant with very high BOD load, Therefore, installation of suitable chemical recovery would not only help in recovering the valuable chemical but also lead to the reduction of organic load in effluents.
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