Development of Aox Standards for Large Scale Pulp and Paper Industries

8/6/2019 Development of Aox Standards for Large Scale Pulp and Paper Industries

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Programme Objective Series (PROBES)

PROBES/10712007

DEVELOPMENT OF AOX STANDARDSFORLARGE SCALE PULP AND PAPERINDUSTRIES

CENTRAL POLLUTION CONTROL BOARDMINISTRY OF ENVIRONMENT & FORESTSWebsite: www.cpcb.nic.in e-mail: [email protected]


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PROGRAMME OBJECTIVE SERIES

PROBES/10712007

DEVELOPMENT OF AOX STANDARDSFOR

LARGE SCALE PULP AND PAPERINDUSTRIES

. .CENTRAL POLLUTION CONTROL BOARDMINISTRY OF ENVIRONMENT & FORESTSe-mail: [email protected] Website: www.epeb.nie.inApril 2007


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CPCB, 200 Copies, 2007

Published By : Dr. B. Sengupta, Member Secretary, Central Pollution Control Board, Delhi - 32Printing Supervision & Layout: P.K. Mahendru and Anamika Sagar.Composing, Laser Typesetting & Cover Page Design: Suresh Chander SharmaPrinted at: DSIDC, New Delhi - 110 020.


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......~ , . ,a[jXeQ)r. +no QI\3?{iCf)'!, m . ~ . - n .Wei. M. MAUSKAR, lAShartman FOREWORD

$ ~ < t ~ , & l l T U T Fl


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Development of AOX Standards for Large Scale Pulp and Paper Industries

Project TeamDr. B. Sengupta,Member Secretary

MIs Central Pulp & Paper ResearchInstitute, Saharanpur

Mr. P. M. Ansari,Additional DirectorDr. R. S. Mahawar,Additional Director

Mr. H. K. Karforma,Senior Environmental Engineer

Mr. S. K. Gupta,Environmental EngineerMrs. V. Hima Jwala, Senior ResearchFellow

Overall guidance

Project execution

Project coordination

Report revision, finalization and editing

Project coordination

Project coordination and follow-up

Project coordination and follow-up


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PREFACE

Bleach plant effluents from pulp & paper industries are known to exhibit toxicity toaquatic life. The toxicity is mainly due to discharge of Halogenated Organic Compoundsformed during bleaching of pulp with chlorine based chemicals particularly molecularchlorine. The increased environmental pressures including the control of the release ofcarcinogenic compounds require the paper industries to adopt cleaner technologiessuch as the Elemental Chlorine Free bleaching techniques (ECF) and Total ChlorineFree (TCF) bleaching techniques for reduction of chlorinated organic compounds. Mostof the chlorinated organic compounds that are carcinogenic, are adsorbable and hencethe discharge of AOX needs to be controlled.

Looking into the problems and limitations of the Indian pulp & paper industries inadoption or up-gradation of their technologies, the Central Pollution Control Board hasundertaken a project on "Development of AOX Standards for Large Scale Pulp & PaperIndustries" with an objective to assess the status of the technologies and permissiblelevels of AOX in effluents in respect of the large scale pulp &paper industries.

The studies were conducted in nine selected pulp & paper industries to collect reliableinformation about level of AOX generation. The studies conducted have provided usefulinformation on the status of the technologies and the levels of AOX discharges in thelarge-scale pulp and paper industries.


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1.0 INTRODUCTIONThe increasing environmental pressures and changing customer preferences inall spheres of life has made it essential that the bleaching techniques adopted byIndian paper industry are also critically evaluated to control and monitor thedischarges of chlorinated organics. It is already known that discharge ofchlorinated organic compounds through effluents ar.d end products from pulp &paper industries have adverse effect on fauna ana flora. The environmentalhazards of bleach plant effluent result from the use of chlorine containing bleachchemicals especially molecular chlorine. The developed countries speciallyScandinavian countries; Canada and USA have slowly eliminated the use ofmolecular chlorine over a period of last two decades and now moving towardstotal chlorine free bleaching (TCF) techniques in a phased manner. The Indianpaper industry, which primarily utilises about 20% wood, 60%nonwood and about20% waste paper, mostly bleach the pulp by chemicals like molecular chlorine,calcium hypochlorite which are responsible for the formation of chiarocompounds. The quantity of chlorine required for bleaching one tonne of pulpranges from 50Kg - 200 Kg. The total available chlorine requirement for differentraw materials is 6-8% in case of Eucalyptus, 8-10% for Bamboo and 8-10% forBagasse. It is therefore essential to make an assessment of the existing AOXlevels in the effluents and technologies that are suitable for achieving the AOXdischarge limits that are acceptable in the Indian Pulp and Paper industries. Thepresent document covers a brief description of the pulp bleaching processes andits environmental impacts, cleaner technologies for the reduction of AOXdischarges, details of the studies conducted for the characterization of wastestreams in large scale pulp and paper manufacturing industries, and the findings,and the recommended discharge limits for AOX.

2.0 PULP BLEACHING AND ITS ENVIRONMENTAL IMPACTS2.1 Bleaching chemicals and Bleaching sequences

The bleaching chemicals are applied in multistage sequences wherein chemicalsare mixed with pulp and allowed a period of retention for bleaching reactions tocomplete. The spent chemicals and dissolved impurities are removed by washingof pulp. The various bleaching chemicals used in pulp bleaching are given inTable-1. The bleaching sequences can conveniently be broken into two segmentsnamely, Delignification Partial Sequence and Brightening Partial Sequence asgiven in Table - 2. The delignification partial sequence has the principle function oflignin removal and the brightening partial sequence increases the brightness.


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Table - 1 : Chemicals Used in Pulp BleachingOxidantsChlorine

FormGas

AdvantagesEffective, economicaldelignification. Goodpractical removal

.DisadvantagesCan cause loss of pulpstrength if usedimproperly.Organochlorineformation.

Hypochlorite Ca(OCI2), NaOCI Easy to make and usesolution -40 gplas CI2Can cause loss of pulpstrength if usedimproperly. Cholorformformation

Chlorinedioxide 7-10 gpl CI02solution in water Achieves high Must be made on site.brightness without pulp I Expensive. Somedegradation. Good I organochlorineparticle removal. I formationOxygen Gas used withNaOH solution Low chemical cost.Provides chloride-freeeffluent from recovery

Used in large amountsrequires expensiveequipment. Can causeloss of pulp strength.- - - - - - - - - - - - - . - " ' - - " . - - - - - - - - - -_ . _ - - ._._.-._-_._---. - " - - " ~ ' - - - " - - ' - " - ' ".- " , _.,_ _-_ ,., .._--- ,--"- , .-_--"_"_'.--'. -- -.-,-_.-.-_._--_._- -_ " .. - ~ - -

HydrogenperoxideOzone

ReductantI Hydrosulfite(for mechanicalpulps only)

Alkali SodiumHydroxide

2-5% solution

Gas in lowconcentration inoxygenSolution ofNa2S20 4 ormade onsite fromNaBH 4 solutionplus S02)5-10% NaOHsolution

Easy to use low capitalcostEffective, provideschloride-free effluentfor recoveryEasy to use. Lowcapital cost.

Effective andeconomical

2

Expensive, poorparticle bleaching.

Decomposes readily.Limited brightness gain

Darkens pulp


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Delignification PartialSequences

CECDED-CECEOOCE

Table ~ : Bleaching Sequences

Brightening PartialSequences

HoHDHEDHOEDOEDDEPD

C - Chlorine,D - Chlorine dioxide,P - Hydrogen peroxide

E -H - Extraction with sodium hydroxideOxygen,Hypoch lorite.The traditional mode of delignification uses chlorine followed by extraction andhypochlorite treatment. Oxygen is another effective delignifying agent which iswidely used to enhance the extraction stage and it is being used in advance ofchlorine in order to reduce the carryover of organic matter to bleach plant. Thehypochlorite and C102 are mainly used for brightening of pulp. CEH is thetraditional sequence used by the Indian paper industries to produce bleachedpulp. But with increasing environmental pressure to reduce or eliminate organochlorine, the use of chlorine is decreasing rapidly with oxygen, peroxide andCl02 providing more environmentally compatible bleaching.

2.2 Formation of chlorinated compoundsThe conventional kraft wood pulp bleaching which includes chlorination typicallyproduces 5.4-9.0 kg of chlorinated organic materials per ton of bleached pulp.Approximately 300 different compounds in bleached pulp industries effluentshave been identified and about 200 of these are chlorinated organic compounds.The types of chlorinated compounds found in Pulp bleaching effluents are listedin table-3:

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Table - 3: Chlorinated compounds found in Pulp Bleaching EffluentsType.-...-._--_ ..._._--_ .._- " "-" .._-_._- .-... __ .... -.-.-.- .. ----_....-Chlorinated acidsChlorinated phenolicsChlorinated aldehydes, Ketonesand lactonesChlorinated hydrocarbonsChlorinated othersHigh molecular weight materials

...._---- "-"". ' ~ - " - " " ' - - " " " ' - " - ~ - ' - - " - - " ' " , ~ , .._.._.

-- " - ..- __ -..No. of Species Amounts____ . _.__ . . .0'_'.__ . -- " _ . __ . . ._40 upto 500g/t pulp40 upto 100g/t pulp454520

upto 4 kg. Cllt pulpIt is well established that a series of chlarophenols are formed during bleachingprocess. The nature and extent of formation of chloro-organics is determinedprimarily by the residual lignin content in the pulp and the type of bleachingchemicals employed. The discharges of chlorinated organic compounds inpaper industries effluents have long been known to exhibit acute, chronic andsome mutagenic toxicity to aquatic life. Studies conducted in developed countriesreveal that the low molecular weight chlorinated compounds are the majorcontributors to toxicity and mutagenicity. Most of the chlorine is otherwise bondedwith high molecular weight organic compounds, which are stable againstbiodegradation, and contributes little to toxicity and mutagenicity. However, thepast studies conducted indicate that these high molecular weight chlorocompounds might also be broken down to smaller more biologically activecompounds and can cause long-term toxic' effects to the recipients. The relativecontribution of the various chlorophenols to AOX is shown in Figure-1.

2.3 Toxic properties of chloro-compounds2.3.1 Chlorophenolics

The Chlorinated compounds present in the alkali extraction bleach effluent arefound to be more toxic and contribute more than 90% of acute toxicity. The chlorocompounds like trichlorophenol, tri and tetra chloroguaiacols in particular mayaccumulate in fish and are responsible for acute toxicity.

2.3.2 Polychlorinated Dioxins & FuransAmong the chlorinated phenolics, the dioxins & dibenzofurans are the groups ofchlorophenoles found to have toxic effects. The prominent among the dioxinsare 2,3,7,8 tetra chloro dibenzo dioxin (TCDD) and 2,3,7,8 tetra chloro dibenzofuran (TCDF). Dioxins are highly Iypophyllic and bioaccumulative compounds.Such compounds are formed when unchlorinated dibenzo dioxin (DBD) &dibenzo furan (DBF) present in unbleached pulp are chlorinated in chlorinationstage. The oil based pulp industry additives particularly brown stock defoamers

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have been identified as potential sources of such compounds. Laboratory studiesindicate a sharp increase in quantity of PCDD and PCOF when elementalchlorine consumption is increased beyond 10-15 kg Cl2/tonne of pulp. Thedioxins are quite resistant to degradation and have an elevated potential forbioaccumulation. The toxic effects of dioxins and the risk doses specified indifferent countries/agencies are given below in table-4. TCDD has been reportedto cause cancer in rats but its effect on humans has been the centre of muchdebate and is still yet to be established.

Table - 4 : Toxic Effects and Risk doses of Dioxins.----- --.--J.---.--- ---.-- ..---.- ---.--.-.-- ".Risk dose* Toxic I health effect--------3-..--- - . -- -_._- -.-6.4 x 10' Cancer

-.-_.._ . _ ~ - - - - - - - - - - - - _ . ~ - - _ . ~ . _ - - - - - - - - - - _ . _ -1.0 Cancer/reproductive.---.----=2------..- ..- - .....------.---..--..-..5.7 x 10' Cancer. ._---_ ..__ ..._.- ...._.'--- - - - - - - ~ _ ..._----_.- _ . _ - ~ _ . _ ....._._--_._._._-

Agency I Country .-EPA..G e ~ m a I 1 L _FDA_.__ .* Picograms of 2,3,7,8 TCDD/kg of body weight/day

AOX 100%

I, - - - - _ . ~ - - - - - - - - ,

Relatively HydorphilicIncludes CompoundsWh ich can Easily BeHydrolysed or Metabolised(e.g. Tricholoroacetic acid)

Relatively Lipophilic(Fat Soluble).Potentially Toxic.PotentiallyBio-accumulable

~ 2 0 %Low MW Material

~ 8 0 %High MW MaterialRelatively Hydrophilic (WaterSoluble). Mainly Non-aromatic,Does not Permeate Cell Walls.1-10% Chlorine By Weight

Low Pow>3Highly LypophyllicBio-accumulative.(e.g. Dioxin - 44% Chlorine By weight)Fig.i. Relative contribution of Chlorophenolic Compounds to AOX

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~ . 3 . 3 Carcinogenic and Mutagenic compoundsBleach plant effluents contain chloroform and carbon tetra chloride which havebeen classified as carcinogens. The hypo-chlorite stage is the major producer ofchloroform. The various chlorinated benzenes, phenols, epoxystearic acid anddichloromethane present have also been classified as suspected carcinogens.Some of the chlorinated compounds formed in Cl2-s tage have been identified asstrong mutagens. However, a very limited information regarding the tendency ofmutagens to bioaccumulation is available.

2.4 Biological effects of Bleach plant effluentsIt is well known that bleach plant effluents are toxic to fish and other organismsmainly due to the presence of chloro-compounds. The biological effects ofchloro-compounds on fish as characterized in the laboratory studies are: Acute toxicity:Egg mortalityPercentage of fertilized egg.Acute toxicity to newly hatched fry. Late effects: Survival and stress tolerance of fry from exposed parents. Effects on behavior: Response to rotary flow. Physiological and Histological sublethal effects:Growth rateHistological changes in lever.Occurrence of parasitic in gills of flounder Bioaccumulation:Effect on primary production in natural mixed phytoplankton populations. Genotoxic effects:Mutagenic effectsCarcinogenic effects.

3.0 KAPPA NO. AND ITS RELATION TO PULP BLEACHINGThe Kappa no. is an index used by the pulp and paper industry to express thelignin content of a pulp. Lignin is responsible for the brown coloration of paper,and is removed by bleaching. Therefore, the lignin content must be well known,so that only a minimum amount of bleach is used. Higher the lignin content moreis the kappa no. The pulp having high lignin content termed as hard cooked pulpand the pulp with low lignin content is termed as soft cooked pulp. The hard

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cooked pulp required more bleaching chemicals to attain particular brightnesscompared to soft cooked pulp.4.0 CLEANER TECHNOLOGIES FOR AOX REDUCTION4.1 Technologies for Kappa no. reduct ion

Pulp & paper industries have incorporated various measures to reduce thekappa no. and also to minimize the carry over of organic matter along withpulp as it governs the bleach chemical demand during the bleaching process.Some of these measures include oxygen delignification, extended deliqruflcation,improved pulp washing, substitution of elemental chlorine with chlorinedioxide, oxidative alkali extraction stage bleaching etc.4.2 Extended Delignification

The pulp and paper industries normally use kraft process in batch or continuousdigestersto remove the lignin as much as possible during pulping of wood basedfibrous raw material but the process has limitation that the wood based fibrousraw material can not be delignified to a low kappa number .Since the kappanumber is the main factor which governs the demand of chemicals for bleachingof the pulp the process was modified to achieve maximum possible delignificationduring cooking of raw materials and now most of the industries in developedcountries are employing RDH, modified continuous cooking, super batchprocess etc tc reduce the kappa number of the unbleached pulp. Modifiedpulping processes are energy efficient, require less chemicals for cooking of rawmaterials and produce the pulp of low kappa number with better strengthproperties as compared to conventional pulping processes. However, the highcapital investment and high level of operation restrict the adoption of thesetechnologies in Indian pulp & paper industries. Agro based pulp and paperindustries normally use soda pulping process.

4.3 Improved Pulp WashingThe pulp mill section of paper industries norrna'ly use brown stock washers forextraction of black liquor and for washing of pulp. The washing efficiency of thesewashers depend on nature and quality of fibrous raw materials. Most of the smallindustries use brown stock washers for washing of pulp produced from agroresidues but the efficiency of these washers are not satisfactory as high carryover of black liquor along with pulp was observed in agro based industries. Sincethe pulp from agro residues is difficult to dewater so the industries can use themodified washing systems such as belt filter press, double wire washer etc, tominimize the carry over of the black liquor with pulp entering the bleachinqsection.

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4.4 Oxygen DelignificationOxygen delignification is a well established technology and most of the pulp millabroad are using this process to reduce the kappa number of pulp beforebleaching stage. Single stage oxygen pre bleaching of the pulp reduces the pulpkappa number by 50-60 % and two stage oxygen pre-bleachinq reduces thepulp kappa number by 80%.The process is used in large pulp & paper industries in the developed countries.Indian paper industries have limitations in adopting the process due to highcapital investments involved and low scale of their operation. The process needsto develop an economically viable oxygen pressure vessel for low scale ofoperation as the capacity of small scale pulp mills in the Country varies from 5-100 ton /day or upgrade capacities of their plants for achieving viability in usingthese processes.

4.5 Chlorine Dioxide SubstitutionThe elemental chlorine is the major source of toxic chlorinated phenolics anddioxins compounds and contribute more than 70% of total AOX . The chlorinedioxide, because of its high oxidation potential, decreases the formation ofchlorinated phenolics, colour, AOX, dioxins etc in addition to improved quality ofpulp. Most of the pulp mill in developed countries have substituted or replacedelemental chlorine with chlorine dioxide. The large pulp and paper industries inthis Country have now started the use of chlorine dioxide also.

4.6 Oxidative alkali extraction bleachingThe addition of small amount of oxygen or peroxide in alkali extraction stageimproves the quality of bleach plant effluent by reducing colour & AOX. Most ofthe large paper industries in India have already started the use of oxygen orhydrogen peroxide in alkali extraction stage. The adoption of modified pulpingand bleaching processes in pulp mill developed Countries has resulted in anincreased recycling or reuse of the waste water to the internal process andefforts are being continued to achieve zero discharge. These industries arehowever required to operate the pulp mill under controlled conditions to reducethe kappa number and also to modify their pulp washing system to minimize thecarry over of black liquor along with pulp in order to reduce the discharge ofchlorinated phenolics compounds.

5.0 NATIONAL/INTERNATIONAL LIMITS FOR AOX DISCHARGESMost of the pulp and paper industries in developed countries have adopted newpulping and bleaching technologies in order to reduce the generation of chloroorganics. Environmental Protection Agency (EPA) has issued the guidelines for

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discharge of AOX, Dioxins and 12 numbers of other chlorinated organiccompounds in the effluents. In India in the year 1992, Ministry of Environment &Forests (MoEF) has notified the discharge limits for chloro-organic compoundsas Total Organic Chlorine (TOCI) -2kg/tonne of paper for large pulp and paperindustries. The discharge limits for organo chlorine in some of the developedcountries are given in Table-5.Table - 5: Discharge Limits Of AOX in Different Countries

COUNTRY Limits, Kg/tonne of paper MODE-- _.-

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related to the size of industry, usage of raw materials, bleaching processemployed, end product, existing effluent treatment facilities, disposal of treatedeffluent etc. The information thus provided was verified and further updatedduring the visit to selected pulp and paper industries.6.2.2 Identification of Sampling Points

The sampling points selected are:(i) Combined bleach plant effluents(ii) Influent to ETP I Primary Clarifier(iii) Overflow of primary clarifier, and(iv) Final treated effluent

6.2.3 Analysis of samplesThe selected pulp and paper industries were visited for indepth study. Two visitswere performed in each of the selected units for conducting the in-depth studiesin order to generate representative and realistic data based information on AOXlevel in these category of pulp and paper industries. The sampling and flowmeasurement were done from identified points for 24 hours composite samplingin order to collect the representative samples. The composite samples collectedwere preserved and transported for further analysis of the following parameters:(i) pH(ii) Suspended Solids(iii) Chemical Oxygen Demand(iv) Biological Oxygen Demand, and(v) Adsorbable Organic Halides (AOX)

6.2.4 Evaluation of Pulp Washing EfficiencyThe efficiency of existing pulp washing system in selected paper industries wasalso evaluated by estimation of carryover of black liquor COD along with pulpgoing to the bleach plant.

6.2.5 Measurement of AOXThe preserved effluent samples (composite) collected from the industries wereanalysed for AOX as per DIN method - 38409H (Flask Procedure) by using DX20 DOHRMANN AOX analyser.

6.2.6 Measurement of Effluent flow ratesThe flow rates of effluent generated were measured at different time intervalsduring the sampling period by using measuring devices such as V notch,

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rectangular notch existing in the drain channels and also by using the floatvelocity method.7.0 INDEPTH STUDIES IN SELECTED INDUSTRIES7.1 Writing & Printing paper manufacturing industries

Unit-1Details of the industry and findings of the study are given in Table 6The industry is mainly based on eucalyptus, bamboo and small amount of pineas the raw materials to produce writing & printing, and Kraft packaging gradepapers. The production of these two grades of papers was 110 tpd and 45 tpdrespectively. The Kappa no. of unbleached kraft pulp produced ranged 26-30,and it is being used both for writing & printing grade and also for unbleached kraftpaper. For the production of writing and printing grade papers the pulp is beingbleached by CEpHH bleaching sequence to a targeted brightness level of 75%ISO. The total AOX load generated is 3.58 Kg/t product (555 Kg/day) which isreduced to 1 .23 Kg/t product (190 kg/day) in the final effluent discharge Theover-all reduction in AOX in ETP is 65.77%.

Table - 6 : Details and findings of study in Unit-1

1.2.3.

4.5.6.7.8.

Installed capacity ,T / YearRaw materialsPaper production, T/Daya. Totalb. Kraftc. W & P GradePulping processKappa no. of unbleached pulpBleaching sequenceBleached pulp brightness,% ISOCharacteristics of waste water(Influent to ETP)a. Flow, M3 IDayb. pHc. Suspended solids, mglld. Suspended solids, Kgl Day

11

- 46,000- Bamboo, Eucalyptus, Pine- 155- 45- 110- Sulphate- 26 - 30- CEpHH- 84.0

- 29290- 7.2- 1080- 31633

Contd ....


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e. Suspended solids, Kg/T Paper - 204f. COD, mg/I - 1313g. COD, Kg/Day - 38458h. C O D , Kg/ T Paper - 248i. AOX, mg/I - 18.94j. AOX., Kg/Day - 555k. AO X , Kg/ T Paper - 3.58

9. Characteristics of treated waste watera. Flow, M3 /Day - 29290b. pH - 7.4c. Suspended solids, mg/I - 90d. Suspended solids, Kg/ Day - 2636e. Suspended solids, KglT Paper - 17f. COD, mg/I - 269g. COD, Kg/Day - 7879h. C O D , Kg/ T Paper - 51i. AOX, mg/I - 6.48j. AOX, Kg/Day - 190k. AO X , Kg/ T Paper - 1.22

10. Efficiency of ETPa. Reduction in SS ,% - 91.67b. Reduction in COD,% - 79.51c. Reduction in AOX,% - 65.78--------------------------------------------------------------------------------------------------------

Unit-2Details of the industry and findings of the study are given in Table 7.The industry is manufacturing writing & printing paper, kraft paper & triplex boardfrom bamboo (50-60%) and mixed hardwoods (40-50%). Th e unbleached pulpof Kappa 25 + 2 is used both for writing and printing grade, and also fo r kraftpackaging & triplex boards. Th e industry produces 156 tlday writing and printingpaper against a total production of 165 t/day. In case of the production of writ ingand print ing grade papers, the pulp is bleached by CEHH/CEHHP bleachingsequence to a brightness level of 78% ISO. Th e total AO X load generated is5.03 kg/t of paper (831 kg/day) which is reduced to 2.50 kg/t of paper production(413 kg/day) after secondary treatment. Th e overall reduction in AO X in the ETPis 50.30%.

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Unit-3Details of the industry and findings of the study are given in Table 8.The industry is producing fine variety of paper from bamboo (90%) andEucalyptus (10%). The production of paper during sampling period was 252 tpd.The pulp having kappa nO.20-22 is bleached by C/O EoHHO bleaching sequenceto a brightness level of 82-84% ISO. The total AOX load generated is 4.49 kg/tpaper productlon'(t tSt kg/day), which is teduced to 2.40 kg/t (603 kg/day) paperproduction after secondary treatment. The overall reduction in AOX during in theETP is 46.72%.Unit-4Details of the industry and findings of the study are given in Table 9.This industry is mainly based on bagasse, bamboo, and eucalyptus in addition tolittle proportion of imported pulp. Presently the industry is producing around63t/day rayon grade pulp, 110 t/day writing & printing paper from eucalyptus andbamboo, and about 110t/day writing and printing paper from 90% bagassebleached pulp and 10% imported bleached pulp. Rayon grade pulp (kappano.16) is bleached by CEHD - S02 bleaching sequence to a brightness level of87% ISO, while Eucalyptus & bamboo pulp of kappa no 18-20 is bleached byCEHHO-S02 bleaching sequence to a brightness level of 83% ISO and bagassepulp of kappa 12-13 by C/OEoD bleaching sequence to brightness level of 85%ISO. The total AOX load generated is 2.32 kg/t production (662 kg/day) which isreduced to 1.37 kg/t production (390 kg/day) after secondary treatment and finaldischarge. The overal l reduction of AOX in the ETP is 41%.

Table - 7: Details and findings of study in Unit-2

1.2.3.

4.5.

Installed capacity, T/ YearRaw materials

Paper production, T / Daya. Totalb. Kraftc. W & P GradePUlping processKappa no of unbleached pulp

13

- 70,000- Bamboo (50-60%)Mixed Hardwoods(40-50%)

- 165- 9-10- 156- Sulphate pulping- 22 - 28

Contd ....


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6. Bleaching sequence - CEHHp7. Bleached pulp brightness,% ISO - 85.08. Characteristics of waste water

(Irif luent to ETP)a. Flow, M3 /Day - 44110b. pH - 8.64c. Suspended solids, mg/I - 3000d. Suspended solids, Kg/ Day - 132330e. Suspended solids, KglT Paper - 802f. COD, mgtl - 1277g. COD, Kg/Day - 56329h. COD, Kg/ T Paper - 341i. AOX, mg/I 18.83J. AOX, g/Day - 831k. AOX , Kg/ T Paper - 5.03

9. Characteristics of treated waste watera. Flow, M3 /Day - 44110b pH - 7.54c. Suspended solids, mg/l - 260d. Suspended solids, Kg/ Day - 11468e. Suspended solids, Kg/T Paper - 70f. COD, mgtl - 272g. COD, Kg/Day - 11998h. COD, Kg/ T Paper - 73i. AOX, mg/I 9.36j. AOX, Kg/Day 413k. AOX , Kg/ T Paper - 2.5010. Efficiency of ETPa. Reduction in SS ,% - 91.33b. Reduction in COD,% _. 78.70c. Reduction in AOX,% - 50.30

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Table - 8: Details and findings of the study in Unit - 31. Installed capacity, T/ Year - 1,00,0002. Raw materials - Bamboo (90 %)

- Eucalyptus(10 %)3. Paper production, T/Daya. Total - 252b. W & P Grade - 2524. Pulping process - Sulphate

5. Kappa no of unbleached pulp - 206. Bleaching sequence - C/DEoHHD7. Bleached pulp brightness,% ISO - 84.08. Characteristics of waste water

(Influent to ETP)a. Flow, M3/Di::IY - 79200b. pH - 7.6c. Suspended solids, mg/I - 1017d. Suspended solids, Kg/ Day - 80546e. Suspended solids, KglT Paper - 320f. COD, mg/ - 1177g. COD, Kg/Day - 93218h. COD, Kg/ T Paper - 370i. AOX, mg/I 14.28j. AOX, Kg/Day 1131k. AOX I Kg/ T Paper - 4.499. Characteristics of treated waste watera. Flow, M3 /Day - 79080b. pH - 7.1c. Suspended solids, mg/I - 235d. Suspended solids, Kg/ Day - 18584e. Suspended solids, KglT Paper - 74f. COD, mg/I - 291g. COD, Kg/Day - 23012h. COD, Kg/ T Paper - 91i. AOX, mg/I 7.62j. AOX, Kg/Day 603k. AOX , Kg/ T Paper - 2.40

10. Efficiency of ETPa. Reduction in SS ,% - 76.89b. Reduction in COD, % - 75.28c. Reduction in AOX, % - 46.68

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Table9 : Details and findings of the study in Unit-4

1. Installed capacity,TlYear:a. Total - 1,49,900b. W&P Grade - 36,000 (Eucalyptus &bamboo)

82,500 (bagasse)c. Rayon pulp - 31,200 (Eucalyptus)

2. Raw material - Bamboo, Eucalyptus & bagasse3. Paper production, T/Day:

a. Total - 285b. W & P Grade - 222c. Rayon pulp - 63

4. Pulping process - Sulphate(Eucalyptus & bamboo)Soda (bagasse)

5. Kappa no of unbleached pulp - 16 (Eucalyptus, RG)13 (bagasse, W & P)20 (Eucalyptus& bamboo, W & P)

6. Bleaching sequence - CEHD (RG)- CEHH D/S02(E)- C/ DEoD ( B)

7. Bleached pulp brightness,% ISO - 86 (Eucalyptus, RG)80 (bagasse, W & P)83 (Eucalyptus, W & P)

8. Characteristics of waste water (Influent to ETP)a. Flow, M3/Day - 61440b. pH - 6.6c. Suspended solids, mgll - 370d. Suspended solids, Kg/ Day - 22733e. Suspended solids,Kg/T paper - 80f. COD, mgll - 485g. COD, Kg/Day - 29798h. COD, Kg/ T Paper - 105i. AOX, mgll - 10.77j. AOX, Kg/Day - 662k. AOX , Kg/ T Paper - 2.32

Contd....16


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9. Characteristics of treated waste watera. Flow , M3 /Day - 61440b. pH - 7.3c. Suspended solids, mg/I - 240d. Suspended solids, Kg/ Day - 14745e. Suspended solids, KglT Paper - 52f. COD, mg/I - 390g. COD, Kg/Day - 23962h. COD, Kg/ T Paper - 84i. AOX, mg/I - 6.35j. AOX, Kg/Day - 390k. AOX , Kg/ T Paper - 1.37

10. Efficiency of ETPa. Reduction in SS ,% - 35.14b. Reduction in COD,% - 19.59c. Reduction in AOX,% - 41.00

Unit-5

Details of the industry and findings of the study are given in Table 10The industry has installed capacity of 300 tonnes/day of manufacturing highquality bleached paper varieties. The main fibrous raw materials used are bambooand wood. The mill has employed cleaner technologies like RDH Pulping, OxygenDelignification with chlorine dioxide bleaching. The CDEoPD bleaching sequenceis used for bleaching of the pulp having Kappa No 15-17. The AOX level in effluentbefore treatment is 1.92 Kg/tonne of paper while after treatment in ETP its levelcomes down to 1.07 Kg/tonne of paper. The over-all reduction in AOX in the ETPis 44%.

Details of the industry and findings of the study are given in Table 11.

The paper industry has installed capacity of 53868 t/year for manufacturing writing& print ing grade of paper. The main fibrous raw materials used for manufacturing

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of quality paper are bamboo,wood,bagasse and grasses( Sabai,khar & Kai). Theindustry has two pulping street, new pulp mill is used to produce wood pulp havingkappa nO.20-21. While the existing old pulp mill with eight nos. of digestors (32 m3each) is used to produce pulp of kappa nO.13-15 from bagasse & grasses. Theindustry is practicing both conventional bleaching (CHH) for pulp of low kappa no.pulp & CDEDD for wood pulp. The AOX level in effluent before treatment is 4.0Kg/tonne of paper while after treatment in ETP its level comes down to 1.84Kg/tonne. The over-all reduction in AOX in the ETP is 54%.

7.2 Newsprint Paper IndustriesUnit-7Details of the industry and findings of the study are given in Table 12The industry is based on bagasse, Eucalyptus and imported Chemi MechanicalPulp (CMP) wood. During sampling period, the production of industry was 276tid of newsprint and 253 tid of writing and printing paper. The chemical pulp ( CP)produced from bagasse & Eucalyptus have Kappa 8-10 & 18-22 respectively.The bagasse & Eucalyptus chemical pulps are bleached by CEH .& CEHHbleaching sequences to the brightness level of 75 & 85% ISO respectively. TheCMP bagasse is bleached by hydrogen peroxide to brightness level of 65% ISO.The newsprint fibre furnish is 40% bagasse CP, 40% bagasse Chemi MechanicalPulp ( CMP) & 20% imported CMP of wood pulp while fibre furnish for writing &printing paper is 75% bagasse CP & 25% hardwood CP. The total AOX loadgenerated based on total production of newsprint together with writing & printingpaper is 1.79 kg/t(946 kg/day) production which is reduced to 0.80 kg/t production (424 kg/day) after secondary treatment. The above AOX level of 1.79 kg/tproduct is the combined AOX generated from newsprint as well as from writingand printing grades. Out of the total production about 10-12% is the importedCMP wood which does not require any bleaching and about 20-22% is thebagasse CMP where the bleaching done IS very mild with hydrogen peroxide andthere is no possibility of AOX generation. The AOX generation is mainly due tothe bleaching of CP of bagasse and wood. The overall reduction in AOX in theETP is 55.30%.

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Table - 10 : Details and finding of the study in Unit - 5---------------------------------------------------------------------------------------------------------------------Exercise Exercise Av.ValuesI II-------------------------------------------------------------------------------.-------------------------------------1. Installed capacity,TIY 90,0002. Raw materials Bamboo and Hard wood3. Writing & printing paper

production TID 281 332 3074. Pulping process RDH (Sulphate)5. Kappa No. of unbl.Pulp 15-17 15-176. Bleaching practice C/DEoPD7. Bleached PulpBrightness,% ISO 86-888. Characteristics of combined waste water (influent to ETP)- Flow m3/d 26537 26878 26708

-pH 8.4 7.96 8.18- Suspended Solids,mg/l 1480 1620 1550- Suspended Solids,kg/t paper 140 131 136- COD,mg/l 1471 1645 1558- COD,Kg/t paper 139 133 136- AOX,mg/l 16.68 27.34 22.01- AOX,kg/t paper 1.58 2.21 1.92

9. Characteristics of Primary clarifier outlet-pH 7.30 7.44 7.37- Suspended Solids,mg/l 160 290 225- COD,mg/l 738 806 772- AOX,mg/l 13.68 24.71 19.2010. Characteristics of final discharge-pH 7.75 7.66 7.71- Suspended Solids,mg/l 120 180 150- Suspended Solids,kg/t paper 11 15 13- COD,mg/l 356 380 368- COD,kg/t paper 34 31 33- AOX,mg/l 11.10 13.29 12.20- AOX,kg/t paper 1 05 1.08 1.07

11. Performance of ETP.- Reduction in Suspended Solids,% 92 86 89- Reduction in COD,% 76 77 77- Reduction in AOX,% 34 51 44

12. Waste waterdischarge,m3/t paper 94 81 88----------------------------------.---------------------------------------------------------------------------.-----

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Table - 11 : Details and findings of the study in Unit - 6ExerciseI ExerciseII Av.Values

------------------------------------------------------------------_._------------------_._---------------------------1. Installed capacity,TIY 538682. Raw materials Wood,Bamboo, Bagasse &Grasses3. Writing &printing paperproduction,T/D 182 213 1984. Pulping process Sulphate process5. Kappa No. of unbl.Pulp- Bamboo/wood 20-21- Grasses/Bagasse 13-156. Bleaching practice- Bamboo/wood C/DEDD

- Grasses/Bagasse CHH7. Bleached Pulp Brightness.% ISO 78-868. Characteristics of combined waste water (influent to ETP)

- Flow m3/d 44590 41340 42965-pH 6.7 7.4 7.05- Suspended Solids,mgll 490 600 545- Suspended Solids,kg/t paper 120 116 118- COD,mg/1 687 782 735- COD,Kg/t paper 168 152 160- AOX,mg/1 18.17 18.30 18.24- AOX,kg/t paper 4.45 3.55 4.009. Characteristics of Primary clarifier outlet-pH 7.10 7.20 7.15- Suspended Solids,mgll 130 140 135- COD,mgll 503 539 521-AOX,mg/1 14.98 12.77 13.88

10. Characteristics of final discharge-pH 7.10 7.30 7.20- Suspended Solids,mg/I 60 40 50- Suspended Solids,kg/t paper 15 8 12- COD,mg/1 144 164 154- COD,kg/t paper 35 32 34- AOX,mgll 8.86 7.77 8.32- AOX,kg/t paper 2.17 1.51 1.84

11. Efficiency of ETP:- Reduction in Suspended Solids,% 87 93 90- Reduction in COD,% 79 79 79- Reduction in AOX,% 51 57 5412. Wastewater discharge,m3/t paper 245 194 220- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - . - - - - -

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Table - 12 : Details and findings of the study in Unit-71. Installed capacity, T/ Year

a. Total - 2,00,000b. Newsprint - 1,00,000 (Bagasse & imported wood pulp)c. W & P Grade - 1,00,000(Eucalyptus& bagasse)

2. Raw materials - Bamboo,Eucalyptus,bagasse Imp. wood pulp3. Paper production,T/Day:

a. Total - 529b. Newsprint - 276c. W & P Grade - 253

4. Pulping process - Sulphate (bagasse & Eucalyptus)CMP(bagasse)5. Kappa no of unbleached pulp - 20 ( Eucalyptus CP)

10 (bagasse CP)6. Bleaching sequence - CEH(bagasse CP)

- CEHH(Euc.CP)- P(bagasse CMP)

7. Bleached pulp brightness, - 85 ( Bagasse, CP)% ISO - 65 (Bagasse, CMP)- 75 (Eucalyptus, CP)

8. Characteristics of waste water (Influent to ETP)a. Flow, M3 IDay - 69120b. pH - 6.3c. Suspended solids, mg/l - 740d. Suspended solids, Kgl Day - 51149e. Suspended solids,Kg/T paper - 97f. COD, mg/I - 853g. COD, Kg/Day - 58959h. COD, Kg/ T paper - 112i. AOX, mg/I - 13.69j. AOX, Kg/Day - 946k. AOX, Kg/ T paper - 1.79

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9. Characteristics of treated waste water

10.

a. Flow, M3 /Dayb. pHc. Suspended solids, mg/Id. Suspended solids, Kg/ Daye. Suspended solids,Kg/T paperf. COD, mg/Ig. COD, Kg/Dayh. COD, Kg/ T paperi. AOX, mg/Ij. AOX, Kg/Dayk. AOX , Kg/ T paperEfficiency of ETPa. Reduction in SS ,%b. Reduction in COD,%c. Reduction in AOX,%

Unit-8

- 68160- 6.95- 90- 6134- 12- 181- 12337- 23- 6.22- 424- 0.80- 88.00- 79.08- 55.30

Details of the industry and findings of the study are given in Table 13.

This newsprint industry is based on hardwoods (Eucalyptus & Casurina) CMP,CP of hardwoods and bamboo/reed (70:30) and the imported CP of softwood.The newsprint production was 25Ot/d during sampling period. The CP producedfrom hardwoods & bamboo/reed having Kappa no. around 20 is bleached byCH/E sequence to a brightness level around 60-65% ISO. While CMP producedfrom hardwoods is bleached by Hydrogen peroxide to brightness level around55% ISO. The newsprint furnish is 70-75% CMP & 25-30% CP includingimported CPo The results indicated that generation of total AOX load is 0.53 kg/tof newsprint (133 kg/day) which is reduced to 0.14 kg/t newsprint(36kg/d)production after secondary treatment. The over-all reduction in AOX is about72.79% during the treatment.

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7.3 Rayon Grade Pulp IndustriesUnit-9Details of the industry and findings of the study are given in Table 14This industry is mainly based on hardwoods (Eucalyptus and Casuarina) formanufacturing about 110t /day rayon grade pulp. The unbleached pulp of kappano. 12.8 is bleached by CEoHEpD bleaching sequence to a brightness level of85% ISO. The total AOX load generated is 0.69-kg/t pulp (76 kg/day), which isreduced to 0.2 kg/t pulp (22 kg/day) after secondary treatment. The low level ofAOX generation is mainly due to low kappa of the unbleached pulp and use ofoxygen in extraction stage and chlorine dioxide in the final stage of bleaching.The overall reduction in AOX level in the ETP is 71.05% .

8.0 GENERAL OBSERVATIONSA summary of the findings of the generation/discharges of AOX, SS and COD indifferent pulp and paper industries is given in Table 15.

8.1 Writing and Printing Grade Paper IndustriesThe summary results of the AOX generation and discharge in large scale writingand printing paper industries are given in Table 16.AOX generation in pulp & paper industries producing writing & printing gradepaper is found to be generally higher than newsprint and Rayon grademanufacturing industries due to high Kappa no. of the pulp and excessive use ofmolecular chlorine for achieving high brightness. Therefore, the generation ofAOX is comparatively higher for writing and printing paper where final brightnessis important. The levels of AOX measured in mill samples vary from 1.92 to 5.32kg.AOX/t paper. In the industries, where chlorine dioxide and oxygen or peroxidereinforced alkali extraction stage are used as bleaching agent, the generation ofAOX is on lower side compared to level of AOX generated using conventionalCEHH bleaching sequences.

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Table - 13 : Details and findings of the study in Unit-81, Installed capacity,T/ Year - 1,00,0002, Raw materials - Bamboo, Eucalyptus, Casurina,Reed, & Imported wood pulp3. Paper production, TlDay - 2504. Pulping process - Sulphate (Eucalyptus,Casurinabamboo and Reed)- CMP (Eucalyptus and Casurina)5. Kappa no of unbleached pulp - 20 (CP)6. Bleaching sequence - CH/E(CP)- P(CMP)7, Bleached pulp brightness,% ISO - 63 (CP)- 50 (CMP)8, Characteristics of waste water (Influent to ETP)

a, Flow, M3 /Day - 27311b. pH - 4.75c. Suspended solids, mg/I - 540d. Suspended solids, Kg/ Day - 14748e, Suspended solids,Kg/T paper - 59f. COD, mg/I - 668g. COD, Kg/Day - 18244h, COD, Kg/ T paper - 73I. AOX, m g / ~ - 4.85l AOX, Kg/Day - 133k. AOX , Kg/ T paper - 0.539, Characteristics of treated waste watera, Flow, M3 /Day - 27305b. pH - 6.70c. Suspended solids, mg/l - 136d. Suspended solids, Kg/ Day - 3714e. Suspended solids,Kg/T paper - 15f. COD, mg/I - 353g. COD, Kg/Day - 9639h. COD, Kg/ T paper - 39I. AOX, mg/I - 1.32j. AOX, Kg/Day - 36k. AOX , Kg/ T paper - 0.14

10 Efficiency of ETPa. Reduction in SS ,% - 74.82b. Reduction in COD,% - 47.16c. Reduction in AOX,% - 72.79--------------------------------------------------------------------------------------------------------------_.

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Table - 14: Details and findings of the study in untt- 91. Installed capacity, T/ Year - 1,00,0002. Raw materials - Eucalyptus & Casurina3. Pulp production, T/Day - 1104. Pulping process - Sulphate5. Kappa no of unbleached pulp - 12.86. Bleaching sequence - CEoHEpD(CP)7. Bleached pulp brightness,% ISO - 848. Characteristics of waste water (Influent to ETP)

a. Flow, M3 /Day - 18360b. pH - 7.70c. Suspended solids, mg/I - 227d. Suspended solids, Kg/ Day - 4168e. Suspended solids,Kg/T paper - 38f. COD, mg/I - 653g. COD, Kg/Day - 11989h. COD I Kg/ T paper - 109i. AOX, mg/l - 4.14j. AOX, Kg/Day - 76k. AOX , Kg/ T paper - 0.69

9. Characteristics of treated waste watera. Flow, M3 /Day - 17208b. pH - 7.30c. Suspended solids, mgll - 50d. Suspended solids, Kg/ Day - 860e. Suspended solids,KglT paper - 7.82f. COD, mg/I - 281g. COD, Kg/Day - 4836h. COD, Kg/ T paper - 44i. AOX, mg/l 1.26j. AOX, Kg/Day 22k. AOX Kg/ T paper - 0.20

10. Efficiency of ETPa. Reduction in SS ,% - 79.36b. Reduction in COD,% - 59.67c. Reduction in AOX,% - 71.48

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

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Table - 15 : AOX Generation in different Pulp & Paper Industr- - - -_. - -_. - - - - -_._ .._--_.- _._ ...._._--_ ...... _ . _ - - - , - - ~ - - - - . _- "- -s. Details of Paper Mill Unit-1 Unit-2 ueu-a Unit-4 Unit-5 Unit-6No - - - - - - - -1 Paper production.Tzday

a, Total 155 165 252 285 307 198b. Kraft 45 10c. W & P Grade 110 156 -- 222 307 198d. Rayon pulp -- -- -- 63 -- --e. Newsprint -- -- -- -- -- --

2. Kappa no of unbleached pulp 26-30 22-28 20 16 (RG) 15-17 20-21(W)10(B) 13-15(B)20(E)

3. Bleaching sequence CEpHH CEHH C/OE)H CEOH COEopO COEOOHO (RG) (W)C/DEoO CHH(B)(B)CEHHD

(W )4. Bleached pulp brightness, 84 85 84 86 87 82

%150 8083

5. Wastewater generated m3/T 18 267 314 2 A C 87 2170paper26


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S. Details of Paper Mill Unit-1 Unit-2 Unit-3 Unit-4 Unit-5 Unit-6 UNo6. AOX generated KglT paper

a. W & P grade 3.58 5.03 4.49 2.32 1.92 4.0b. Rayon pulp -- -- -- -- -- --c. Newsprint -- -- .- -- -- -- 1

7. Total AOX at final discharge 1.22 2.50 2.40 1.37 1.07 1.84 0KglT paper8. SS removal KglT paper8.1 SS in untreated eff!. 204 802 320 80 136 1188.2 SS in treated eff!. 17.0 80.0 74.0 52.0 13 12 19. COD removal KglT paper9.1 COD in untreated eff!. 248 341 370 105 136 1609.2 COD in treated eff!. 51.0 73.0 91.0 84.0 33 34 210. Efficiency of ETP

a. Reduction in TSS, % 91.67 91.33 76.89 35.14 89 90 8b. Reduction in COD,% 79.51 78.70 75.28 19.59 77 79 79c. Reduction in AOX, % 65.78 50.30 46.72 41.00 44 54 55

Note: Unit-1; Unit-2; Unit-3; Unit -4; Unit -5; Unit -6; Unit -7; Unit -8; Unit -9CP- Chemical pulp; CMP :- Chemi-mechanical pulp;C - Chlorination; E- Extraction; H- HypochloriteP - Hydrogen peroxide 0 - Chlorine dioxide;O - Oxygen(RG)- Rayon grade;(W) Wood,(B) Bagasse,(E) Eucalyptus

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8.2 Newsprint Paper IndustriesThe summary results of the AOX generation and discharge in newsprint paperIndustries are given in Table 17.The level of AOX generation in case of chemi-mechanical pulp(CMP) bleachedwith hydrogen peroxide, is negligible. Therefore, the AOX generation kg/tnewsprint mainly depends on the proportion of CMP and CP in the pulp. Thelevel of AOX measured in effluent samples collected from newsprint Industries isless than 1.0 kg AOX/t paper. The pulp furnish used in these industries containsmajor portion of mechanical pulp which is bleached with Hydrogen peroxide whilechemical pulp is given a mild bleaching action with chlorine based chemicals toachieve 60% brightness level. The low degree of brightness in newsprint paperand use of per-oxide in bleaching resulted in low level of AOX in the effluent.

8.3 Rayon Grade Pulp IndustriesThe summary results of the AOX generation and discharge in large scale RayonGrade Pulp Industries are given in Table 18.The kappa of unbleached in rayon grade pulp is quite low i.e 12-16 which requiredless quantity of the bleaching chemicals mainly chlorine and chlorine dioxideresulting in low level of AOX in effluent. The AOX generation level rangesbetween 1.48 to 1.68 kg/t of pulp.

8.4 Effluent Treatment Plants(i)

(ii)

(iii)

Studies conducted in the industries reveal that biological effluent treatmentplants appears to be effective in removal of chlorinated organiccompounds. The maximum reduction in AOX i.e. about 70% is observedin newsprint and rayon grade pulp industries while in writing and printingpaper industries, the reduction in AOX varies from 41 to 55 %. The highreduction in AOX in newsprint and rayon grade pulp industries may bebecause of low level of AOX in combined waste water and other reasonsmay be perhaps because of low molecular weight AOX compounds.There is a wide variation in quantity of wastewater discharged per tonne ofpaper. The wastewater quality varies from industry to industry dependingupon the raw materials used and quality of end product. The lowest figuresof 109-130 m3/t were observed in newsprint followed by 155 m3/t in rayongrade pulp and 190-315 m3/t in writing and printing paper industries.The generation and discharge of suspended solids in wastewaters alsovary from industry to industry and also from product to product. The

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reduction in SS during external treatment (ETP) observed varies from 35to 92%.(iv) The generation and discharge of COD measured also vary from industryto industry depending on end product. The reductions in COD observedafter secondary treatment varied from 47 to 80 % except in Unit-4, whereCOD reduction measured was only 20 % which may be because ofunstabilization of new bagasse based pulp industries at the time of samplecollection.(v) The industries which have accomplished the modernization of bleach plantoperation by inducting the chlorine dioxide, and oxidative alkali extractionstage with oxygen and hydrogen peroxide certainly has the reduced AOXdischarges.

Table - 16 : AOX generation ana mscnarqe in large scale Writing & Printing paperIndustries-_._._._-_._-"-_._--- ..... ,,--_._._-------_._--_._.._ - - - - - ~ - - - - - - -s. Parameters Unit 1 Unit 2 Unit 3 Unit 5 Unit 6No- - . ~ - - _ ... --- . ______ _____ ~ , 4. '_, .._.__ _ _______ ' " _ . ~ ~ _______ ,,____ _._______1. Raw materials Bamboo, Bamboo & Bamboo & Bamboo & Bamboo,Pine & wood Eucalpytus Wood woodEucalyptus (Mixed grasses &hardwood) Bagasse2. Pulping process Sulphate Sulphate SUlphate Sulphate Sulphate(RDH)3. Pulp Kappa No. 26-30 22-28 20 15-17 20-214. Oxygen delignification No No No Yes No5. Bleaching sequence CEoHH CEHHP C/DEoHHD C/DEopD C/DEDDCHH6. Total PaperProduction, tlday

a. Writing & Printing 110 156 252 307 198b. Others 45 10

7. Total CI2 Applied % 10.5 16.2 9.45 4.6 9.5+14.08. Total Elemental CI2,% 6.0 7.70 5.50 3.5 6.0+5.09. Chlorine dioxide,% 0.25 1.10 3.510. AOX content, mgll

a. Influent 18.94 18.83 14.28 2201 18.24b. Effluent (Final) 6.48 9.36 7.62 12.20 8.3211. AOX level, kg/t paper

a. Generation 5.05 5.32 4.49 1.92 4.0b. Final Discharge 1.72 2.65 2.39 1.07 1.84

12. Reduction in AOX, % 66 50 47 44 5413. Effluent discharge, 189 267 314 88 220

m3/t paper

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Table - 17 : AOX generation and discharge in Newsprint paper Industries

Parameters

Raw materials

Kappa No.- Chemical Pulp- Mechanical pulpBleaching SequencesChemial PulpMechanical Pulp

Unit-8

Bamboo, Eucalyptus,Casurina, Reed andImp. wood pulp

20

CHEP+P

Unit-7

Bagasse, Bamboo,Eucalyptus andImp. wood pulp

20-Eucalyptus10-Bagasse

CEH -BagasseCEHH-EucalyptuspTotal Chlorine applied, %Total Elemental Chlorine,%Newsprint production,t/dOther variety(W&P),t/dTotal Flow,m3/dAOX,Level-Influent,mg/I-Effluent" "AOX,Kg/t product-Generation-Final DischargeReduction in AOX,%

5.804.00250

27311

4.851.32

0.530.1472.79

9.506.0027625369120#

13.69#6.22#

1.79#0.80#55.20

-----------------------------------------------------------------------------------------------------------------(#) Includes writing and printing paper grade street

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Table - 18 : AOX generation and discharge in Rayon grade pulp Industries--_._--_.._-----_.__ . _ - - - - - - - - ~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ - - - - - - - - - - - - - - - - -Parameters Unit-9 Unit-4Raw materials Eucalyptus,CasurinaPulp Kappa No 12.8Bleaching Sequences CEoHEpDTotal Chlorine applied, % 4.60

Eucalyptus16.00CEHD5.5

Total Elemental Chlorine,%Total pulp production, tidTotal Flow,m3/dAOX Level,mg/lInfluentEffluel'lt

AOX,Kg/t pulp-Generation-Final DischargeReduction in AOX,%

2.50110

18360

4.141.26

0.690.2071.48

2.806361440#

41.00

(#) Includes writing and printing paper grade streets from Bagasse Eucalyptusand Bamboo.

9.0 CONCLUSIONS(i) Most of paper industries are producing varieties of paper depending onthe market needs.

(ii) Almost all the paper industries are using diverse raw materials due to nonavailability of conventional single raw material and asa consequence, theperformance of existing equipment and technology is usually below theexpected standards.31


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(iii) In most of the paper industries studied, the effluent treatment plants(ETPs) are having treatment loads more than their designed capacitybecause industries have continued with their capacity expansionprogrammes perhaps without upgrading their ETPs.

(iv) The generation of AOX measured in effluents from both rayon grade pulp& newsprint industries was below 1.0 kg AOX/t paper. The degradation ofAOX in biological treatment plant observed is more than 70% and the levelof AOX measured was further reduced below 0.50 kg/t paper in finaldischarge. The higher reduction of AOX in these categories of industriescompared to writing & printing paper industries may be because of lowinitial concentration of AOX in influents.(v) The generation of AOX measured varies from 2.0 to 5.30 kg AOX/t paper.The lower value i.e 2.0 kg was measured in relatively modern industry (Unit-5) employing RDH pulping, oxygen delignification with chlorinedioxide in bleaching processes. In general, the generation of AOX inwriting & printing paper industries varied from 1.92 to 5.32 kg AOX/tpaper. The degradation of AOX in biological treatment plant varies from44 to 65 % and the level of AOX in final discharge reduced from 2.0-5.3kg to 1.0 - 2.65 kg of AOX/t paper in these category of industries. Thevariation in performance of ETP for removal of AOX may also be due toinitial high concentration of AOX in terms of mg/l due to varying quantity of

water consumed per tone of paper. The main reason of high level of AOXmay be because of use of high dosage of molecular chlorine due to highcarryover of organic matter alongwith pulp to bleaching section & alsorequirement of high brightness of end product. The results of AOXassessed indicate that the generation of AOX at source is lower in theindustries using modified pulping & bleaching processes, where thegeneration of AOX is about 2.00 kg which is further reduced to 1.00 kg/tpaper in final discharge. However, some paper industries have alreadystarted the use of chlorine dioxide & oxidative alkali extraction bleaching toimprove the quality of pulp & bleach plant effluent.(vi) The discharge of waste water in wnting & printing paper industriesmeasured during study was comparatively higher & in some industries the

final discharge of effluent measured was more than 270m3/t paper. Inmost of industries, the treated effluent is being discharged into river except(Unit-7) where almost entire quantity of treated effluent is utilized for landirrigation by local farmers.

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10.0 RECOMMENDATIONS(i) The newsprint grade paper and rayon grade pulp industries may continueto use the existing pulping & bleaching conditions, since the final

discharge of AOX in these categories of industries is well below 1.0kgAOX/t of product. However, in rayon grade pulp industries, the generation& discharge of AOX levels could be further reduced to lower levels by littlesubstitution of molecular chlorine with chlorine dioxide without anymodification in existing operating conditions. It is observed that theindustries studied are using chlorine dioxide in final stage of bleaching,where the generation of AOX is negligible.

(ii) The higher level of AOX appears to be only in writing and printing pulp &paper industries especially in those which 'are using molecular chlorine orvery little chlorine dioxide is used to bleach the pulp to high brightnesslevel where final discharge of AOX varies from 2.40 to 2.70 kg/t of paperwhile in industries using modified pulping & bleaching processes, the finaldischarge of AOX varies from 1.0 to 2.0 kg/t of paper.(iii) Attempts should be made to reduce the generation of AOX at sourcethrough (a) controlled pulp industry operation for maintaining low kappa noof pulp, (b) improved pulp washing technique to reduce chemicalcarryover with the pulp, (c) use of Oxygen delignification process toreduce Kappa no of pulp, (d) use of Chlorine dioxide substitution in placeof elemental chlorine, (e) use of Oxygen at alkali extraction stage, and (f)regular monitoring of Effluent Treatment Plant for its proper operation.

11.0 FINALIZATION AND NOTIFICATION OF AOX STANDARDSThe standards of AOX recommended by the Peer & Core Committee are asfollowsSINo. Discharge limit of AOXI t o!-'pape.r Date of implementation1. 2.0 Kg/t of paper From January 01,20022. 1.0 Kg/t of paper From April 01,2002

Ministry of Environment & Forests (GOI) has finalized and notified the followingstandards of AOX in case of Large scale pulp & paper industries vide notificationG.S.R.546(E), dated 30.08.2005. The maximum permissible discharge limits forAOX specified in this notification are:(A) 1.50 Kg/t of paper produced with effect from the date of notification i.e30.8.2005, and(B) 1.00 Kg/t of paper produced with effect from the 1st day of March,2008.

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Development of Aox Standards for Large Scale Pulp and Paper Industries

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