r. V

eering

Regin

form

filtration techniques.

demand for industrial establishments to meet human or poorly treated effluents are discharged to receiving

mentploitation of available resources, leading to pollution

of the land, air and water environments. The pulp and

paper industry is one of the most important industries

of the North American economy and ranks as the fifth

largest in the U.S. economy (Nemerow and Dasgupta,

1991). In Canada, the pulp and paper industry

accounts for a major portion of the countrys economy

The high water usage, between 20,000 and 60,000

gallons per ton of product, (Nemerow and Dasgupta,

1991) results in large amounts of wastewater genera-

tion. The pulp and paper industry is considered as the

third largest polluter in the United States (US). It has

been estimated that the pulp and paper industry is

responsible for 50% of all wastes dumped into Cana-requirements have created problems such as overex- waters.D 2004 Elsevier B.V. All rights reserved.

Keywords: Pulp; Pulp and paper; Wastewater; Treatment

1. Introduction

The rapid increase in population and the increased

pollutants characterized by biochemical oxygen de-

mand (BOD), chemical oxygen demand (COD), sus-

pended solids (SS), toxicity, and color when untreatedcoagulation, chemical oxidation, and ozonation. Chlorinated p

efficiently reduced by adsorption, ozonation and membranePulp and paper mills generate varieties of pollutants depending upon the type of the pulping process. This paper is the state

of the art review of treatability of the pulp and paper mill wastewater and performance of available treatment processes. A

comparison of all treatment processes is presented. Combinations of anaerobic and aerobic treatment processes are found to be

efficient in the removal of soluble biodegradable organic pollutants. Color can be removed effectively by fungal treatment,

henolic compounds and adsorable organic halides (AOX) can beTreatment of pulp and pape

D. Pokhrel, T

Department of Environmental and System Engin

3737 Wascana Parkway,

Received 2 July 2003; received in revised

Abstract

Science of the Total Environin terms of value of production and total wages paid

(Sinclair, 1990). The wood pulping and production of

the paper products generate a considerable amount of

0048-9697/$ - see front matter D 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.scitotenv.2004.05.017

* Corresponding author. Tel.: +1-306-5854094; fax: +1-306-

5854855.

E-mail address: t.viraraghavan@uregina.ca (T. Viraraghavan).mill wastewatera review

iraraghavan*

, Faculty of Engineering, University of Regina,

a, SK, Canada S4S 0A2

29 January 2004; accepted 7 May 2004

www.elsevier.com/locate/scitotenv

333 (2004) 3758das waters (Sinclair, 1990). The effluents from the

industry cause slime growth, thermal impacts, scum

formation, color problems, and loss of aesthetic beauty

in the environment. They also increase the amount of

toxic substances in the water, causing death to the

zooplankton and fish, as well as profoundly affecting

the terrestrial ecosystem.

papermaking. High amounts of wastewater are gene-

rated at different stages of this process.

2.4. Thermo-mechanical pulping (TMP)

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758382.1. Mechanical pulping

The yield of the pulp by this process is as high as

9095% (Smook, 1992) but the quality of the pulp is

of low grade, highly colored, and contains short

fibers.

2.2. Chemical pulping

The wood chips are cooked with appropriate

chemicals in an aqueous solution at an elevated

temperature and pressure to break chips into a fibrous

mass. The yield of the pulp by this process is about

4050% of the original wood material (Smook,

1992). The chemical pulping is carried out in two

media: alkaline and acidic.

(a) Kraft process: The woodchips are cooked in aThe growing public awareness of the fate of these

pollutants and stringent regulations established by

the various governmental authorities such as provin-

cial and federal agencies are forcing the industry to

treat effluents to the required compliance level before

discharging them in to the environment. Many stud-

ies have been conducted so far on this sector regard-

ing the impacts as well as the control of the

pollutants. Berube and Kahmark (2001), Kahmark

and Unwin (1996, 1998, 1999), and Srinivasan and

Unwin (1995) have reviewed pollution control as-

pects of the pulp and paper industry. However, all

these reviews have focused on the state of the art in

integrated pollution management and lack a compara-

tive evaluation of various treatment processes partic-

ular to the water pollution control. This review,

therefore, would examine the pollution control sys-

tems and compare the performance of the effluent

treatment measures in use.

2. Process description

Pulping is the initial stage of the paper making

industry and provides the processed material. It is the

largest source of the pollution in the whole process ofsolution of sodium hydroxide (NaOH) andThis process involves steaming the raw materials

under pressure for a short period, prior to and during

refining. The thermo-mechanical process is further

modified using chemicals during the steaming stage,

and the process is called chemi-thermomechanical

pulping (CTMP).

2.5. Papermaking

The paper making operation consists of two parts;

one is stock preparation by treating the pulp to the

required degree of fitness and the other is paper

making where the treated pulp is passed through

continuous moulds/wires to form sheets.

3. Sources of pollution

Each pulping process utilizes large amounts of

water, which reappear in the form of an effluent.

The most significant sources of pollution among

various process stages are wood preparation, pulping,

pulp washing, screening, washing, bleaching, and

paper machine and coating operations. Among the

processes, pulping generates a high-strength waste-

water especially by chemical pulping. This wastewa-

ter contains wood debris and soluble wood materials.

Pulp bleaching generates most toxic substances as it

utilizes chlorine for brightening the pulp. Pulp fibers

can be prepared from a vast majority of plants insodium sulfide (NaS2). This process is widely

used.

(b) Sulfite process: The wood chips are cooked in a

mixture of sulfurous acid (H2SO3) and bisulfide

ions (HSO3) to dissolve lignin.

2.3. Chemo-mechanical pulping (CMP)

The raw material is first treated chemically and

then subjected to drastic mechanical treatment to

separate the fibers. The efficiency of pulp obtained

ranges from 8590% and the strength of the pulp is

relatively better than the pulp from the mechanical

pulping alone.nature such as woods, straws and grasses, bamboos,

or canes and reeds. Wood is the most abundant source

of papermaking fiber. Wood consists of various com-

pounds (lignin, carbohydrate, and extractives) which

are hard to biodegrade, and these derivatives are

washed away from the fibers during the washing,

dewatering, and screening processes. Depending upon

the type of the pulping process, various toxic chem-

icals such as resin acids, unsaturated fatty acids,

diterpene alcohols, juvaniones, chlorinated resin

acids, and others are generated in the pulp and paper

making process. The pollutants at various stages of

the pulping and paper making process are presented in

Fig. 1.

It is clear that an individual pulping stage gene-

rates different quantities, qualities and types of

pollutants. The wastewater pollution load from indi-

vidual pulping and papermaking process is given in

Table 1.

The amount of pollutants produced by an indivi-

dual mill is an important indicator to evaluate the

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 39Fig. 1. Pollutants from various sources of pulping and papermaking (US EPA, 1995).

Sweden for selected process are presented in Table

3. The pollutant load discharge guidelines for the pulp

and paper industry of some countries are presented in

Table 1

Typical wastewater generation and pollution load from pulp and

paper industry (Rintala and Puhakka, 1994)

Process Wastewater

(m3/adt pulp

or paper)

SS

(kg/adt

pulp)

COD

(kg/adt

pulp)

Wet debarking 525 nr 520

Groundwood pulping 1015 nr 1532

TMP -unbleached 1030 1040 4060

TMP-bleached 1030 1040 50120

CTMP-unbleached 1015 2050 70120

CTMP-bleached 1015 2050 100180

NSSC 2080 310 30120

Ca-sulfite (unbleached) 80100 2050 nr

Ca-sulfite (bleached) 150180 2060 120180

Mg-sulfite (unbleached) 4060 1040 60120

Kraft-unbleached 4060 1020 4060

Kraft-bleached 6090 1040 100140

Paper making 1050 nr nr

Agrobased small

paper mill

200250 50100 10001100

nrnot reported; adtair dry ton; NSSCneutral sulfite semi-

Table 3

Comparison of actual emissions from pulp mills (TAPPI, 1990)

Country Parameters

SS

(kg/adt)

BOD

(kg/adt)

COD

(kg/adt)

AOX

(kg/adt)

N

(kg/adt)

P

(kg/adt)

Bleach kraft

USA 5 5 2.2

Sweden 3.8 12 68 2 0.23 0.09

Bleached sulfite

Sweden 6.8 17.8 145 1.8 0.3 0.10

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 375840performance of the system as well as a crosscheck

whether the mills have followed the guidelines. Table

2 provides performance data of selected processes and

chemicals.mills.

The environmental guidelines on discharge vary

with countries. The emission data from USA and

was three to eight times lower than it was in the softTable 2

Typical pollution load per ton of production (kg/ton)

Process Pollutants

SS BOD COD Color Reference

Deinking 11 54 Vlyssides and

Economides

(1997)

Wood yard 3.75 1 2 Springer (2000)

Pulping 13.5 5 1.5 Springer (2000)

Bleaching 6 15.5 40 Springer (2000)

Papermaking 30.8 10.8 1.5 Springer (2000)

Riocell

(Brazil)

0.40.5 0.20.3 55.5 1920a Foelkel (1989)

Large mill

(India)

31.2 13 82.4 Srivastava et al.

(1990)

Small mill

(India)

140.3 152.26 639.4 Srivastava et al.

(1990)

Sweden 0.7 0.2 7.6 Carlson et al.

(2000)

a PtCo (kg/ton).wood kraft mill. The general characteristics of the

Table 4

Discharge limits (monthly, semiannual, or annual verges) forTable 4.

4. Wastewater characteristics

The characteristics of the wastewater generated

from various processes of the pulp and paper industry

depend upon the type of process, type of the wood

materials, process technology applied, management

practices, internal recirculation of the effluent for

recovery, and the amount of water to be used in the

particular process. As an example, Mohamed et al.

(1989) reported that the load of chlorinated phenols

and acids in the wastewaters of hardwood kraft millbleached kraft pulp

Country Parameters

SS

(kg/adt)

BOD

(kg/adt)

COD

(kg/adt)

AOX

(kg/adt)

Reference

Canada 9.514.5 5.530 1.41.5 TAPPI, 1990

Finland 515 6.834 90 1.4 TAPPI, 1990

Norway 5 90 6 TAPPI, 1990

Sweden 0.35.8 7.517 39107 1.52 TAPPI, 1990

Belgium 714.4 2.35.4 2263 1.5 TAPPI, 1990

France 6.510 3.330 4895 TAPPI, 1990

USA 3.86

(8.47)

2.41

(4.52)

Reserved 0.272

(0.476)

US EPA, 2000

The U.S. EPA values are monthly average values for new bleached

kraft mill. The values in the ( ) are daily maximum allowable.

The pollutants discharged from the pulp and paper

Table 5

Typical characteristics of wastewater (mg/l) at different processes (Bajpai, 2000)

Process Parameters

pH SS BOD5 COD Carbohydrate Acetic

acid

Methanol N P S

TMP (1) 383 2800 7210 2700 235 25 12 2.3 72

TMP (2) 4.2 810 2800 5600 1230

CTMP 500 30004000 60009000 1000 1500 167

Kraft bleaching 10.1 3774 128184 11241738 0 4076

Kraft foul (1) 8.0 16 568 1202 421 5.9

Kraft foul (2) 10.2 0 10,700 16,000 306 1 91

621

321

61

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 41industry affect all aspects of the environment such as

water, air and land. Makris and Banerjee (2002)wastewater produced at various process stages and

pollution sources are given in Tables 5, 6 and 7.

5. Fate and effects on the environment

Kraft foul (3) 9.510.5 0 55008500 10,00013,000

Sulfite

condensate (1)

2.5 20004000 40008000

Sulfite

condensate (2)

2.85.9 37005110 980027,100

NSSC Pulping:

Spent liquor 253 13,300 39,800

Chip wash 6095 12,000 20,600

Paper mill 800 1600 5020studied the fate of the resin acid in the secondary

treatment system. Various authors at different times

reported the appearance of toxic effects on various fish

species due to exposure of pulp and paper mill efflu-

ents. Many authors reported the presence of toxic

pollutants in fish or toxic effects on fish such as

respiratory stress, mixed function oxygenase activity,

toxicity and mutagenicity, liver damage, or genotoxic

effects, and lethal effects on the fishes exposed to pulp

Table 6

Characteristics of wastewater (mg/l) at various pulp and paper processes

Process Parameters

TS SS BOD5

Wood preparation 1160 600 250

Drum debarking 20173171 480987

Bleach kraft mill 34 23

Newsprint mill 3750 250 and paper mill wastewaters (Owens et al., 1994; Vass

et al., 1996; Schnell et al., 2000b; Lindstrom-Seppa et

al., 1998; Leppanen and Oikari, 1999; Johnsen et al.,

1998; Erisction and Larsson, 2000). Baruah (1997)

reported on serious concerns related to the surface

plankton population change in Elengabeels wetland

ecosystem in India due to untreated paper mill effluent

discharge into the system. Yen et al. (1996) reported on

the possibility of the sub-lethal effects to the aquatic

75008500 350600 0.021.55 120375

250 800850

8401270

0 3200 90 55 10 868

0 820 70 86 36 315

0 54 9 11 0.6 97organisms in the Dong Nai River in Vietnam due to the

effluents discharged from a pulp and paper mill.

However, there are also some contradictory reports

by other authors. Kovacs et al. (2002) reported no

significant evidence of depressed plasma steroids nor

increase in mixed function oxygenase (MFO) activity

in fish associated with pulp mill effluent. Dsurney et

al. (2002) and Felder et al. (1998) indicated no

significant adverse effect in sediments, and river biota

References

COD AOX Resin

(Ag/l)Color

(PtCo)

Nemerow and

Dasgupta (1991)

2050 Springer (2000)

12.5 69 Wayland et al. (1998)

3500 16 1000 Tardif and Hall (1997)

BOD

(mg/l

98

262

13,08

10

109

112

36

17

156

14

1050 4870 DB Mandal and Bandana (1996)

16 78 Vlyssides and

56

42

17

24

wn;

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 375842or on fish attributable to the treated mill effluent.

Table 7

Characteristics of wastewater at various pulp and paper processes

Process Parameters

pH TS

(mg/l)

SS

(mg/l)

Large mills (India) 11.0 5250 1233

Small mills (India) 12.3 15,120 4890

Digester house 11.6 51,589 23,319

Combined effluent 7.6 3318 2023

TMP whitewater 4.7 91

TMP whitewater 4.7 105

Kraft mill 8.2 8260 3620

Pulping 10 1810 256

Kraft mill (unbleached) 8.2 1200 150

Bleached pulp mill 7.5 1133

Bleaching 2.5 2285 216

Pulp and paper 7.8 4200 1400

News air and land paper

deinking

8.3 450 400

Paper making 7.8 1844 760

Paper mill 8.7 2415 935

Paper machine 4.5 503

Paper machine 8.3 1032

a Unit [Optical Density (O.D) at 465 nm]; DB means dark broStepanova et al. (2000) reported no clear evidence of

mutagens in most of aquatic animals studied in Lake

Baikal due to Baikalsk pulp and paper mill wastewater

discharged to the lake. Wayland et al. (1998) reported

no effect on the tree shallow, which feed on the insects

downstream of the pulp mill.

Howe and Michael (1998) studied the effects of the

treated pulp mill effluent on irrigated soil in northern

Arizona, which showed serious soil chemistry change.

Dutta (1999) investigated the toxic effect of the paper

mill effluent (treated) applied to a paddy field in

Assam, India. Gupta (1997) and Singh et al. (1996)

reported high loads of organic pollutants derived from

the paper mill wastewater in Tamilnadu, and Punjab,

India, respectively. Singh et al. indicated high level of

coliform bacteria in the effluent too. However, Archi-

bald (2000) indicated that the presence of coliform

bacteria in the pulp and paper effluent did not neces-

sarily mean a health hazard to the environment unless

pathogens were observed. Skipperud et al. (1998) and

Holmbom et al. (1994) reported the presence of various

trace metals in the pulp and paper mill effluents at low

levels. King et al. (1999) reported elevated levels ofMn

accumulation in the Crayfish exposed to the paper millwastewater. Mandal and Bandana (1996) reported on

Economides (1997)

1 953 Black Gupta (1997)

5 845 DB Dutta (1999)

0 723 243 Yen et al. (1996)

0 Dilek and Gokcay (1994)

LY means light yellow.References

5

)

COD

(mg/l)

Color

(PtCo)

3 2530 black Srivastava et al. (1990)

8 6145 DB Srivastava et al. (1990)

8 38,588 16.6a Singh et al. (1996)

3 675 1.0a Singh et al. (1996)

0 2440 Jahren et al. (1999)

5 2475 Jahren et al. (2002)

4112 4667.5 Rohella et al. (2001)

0 Dilek and Gokcay (1994)

5 250 Nemerow and Dasgupta (1991)

6 2572 4033 Yen et al. (1996)

0 Dilek and Gokcay (1994)health impacts such as diarrhea, vomiting, headaches,

nausea, and eye irritation on children and workers due

to the pulp and paper mill wastewater discharged to the

environment. High carbon dioxide level in the pulp and

paper mill effluents as a potential source of distress and

toxicity to rainbow trout was reported by Oconnor et

al. (2000).

6. Wastewater treatment

Pollution from the pulp and paper industry can be

minimized by various internal process changes and

management measures such as the Best Available

Technology (BAT). Dube et al. (2000) reported a

60% reduction in effluent BOD due to an internal

process change in Irving Pulp and Paper Limited,

Canada. The estimated data by Springer (2000)

showed that the water use in the US in 1959 was about

250 m3/adt whereas water use in 1995 was reduced to

50 m3/adt. However, the average water use for the pulp

and paper mills in India was still 200259 m3/ton of

paper production (Gune, 2000). Several authors have

suggested internal process change as a measure to

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 43control pollution (Reilama and Ilomaki, 1999; Webb,

1994; Dey et al., 1991). Raghuveer and Sastry (1990)

reported BOD, COD, and color reduction by internal

management measures. However, the treatment of the

wastewater by various external processes is essential.

Since pulp and paper industry discharges varieties of

pollutants, the treatment methods also vary.

6.1. Physicochemical treatment

Physicochemical treatment processes include re-

moval of suspended solids, colloidal particles, floating

matters, colors, and toxic compounds by either sedi-

mentation, flotation, screening, adsorption, coagula-

tion, oxidation, ozonation, electrolysis, reverse osmo-

sis, ultra-filtration, and nano-filtration technologies.

6.1.1. Sedimentation/flotation

Suspended matters present in the pulp and paper

wastewater are comprised primarily of bark particles,

fiber, fiber debris, filler and coating materials. Thomp-

son et al. (2001) stated that sedimentation was the

preferred option within the paper mills in the UK, and

contributed to more than 80% removal of the sus-

pended solids on an average. Rajvaidya and Markan-

dey (1998) stated that the design value of the primary

clarifier was 7080% in average. Azevedo et al.

(1999) reported on the effect of pH on pulp settal-

ability. Gubelt et al. (2000) reported 6595% removal

of TSS by dissolved air flotation and it was an

unstable unit. However, Wenta and Hartmen (2002)

mentioned that dissolved air flotation was able to

remove 95% of the TSS.

6.1.2. Coagulation and precipitation

Coagulation and flocculation is normally employed

in the tertiary treatment in the case of pulp and paper

mill wastewater treatment and not commonly adopted

in the primary treatment. Tong et al. (1999) and

Ganjidoust et al. (1997) carried out a comparative

study of horseradish peroxide (chitosan) and other

coagulants such as (Al2(SO4)3), hexamethylene di-

amine epichlorohydrin polycondensate (HE), poly-

ethyleneimine (PEI), to remove adsorbable organic

halides (AOX), total organic carbon (TOC), and color.

The authors indicated that modified chitosan was far

more effective in removing these pollutants than othercoagulants. Wagner and Nicell (2001) investigated thetreatment of foul condensate, defined by phenolic

compounds, and toxicity using microtox assay from

kraft pulping by horseradish peroxide and H2O2 and

found a total phenol reduction below 1 mg/l and

toxicity (microtox assay) reduction by 46%. Dilek

and Gokcay (1994) reported 96% removal of COD

from the paper machine, 50% from the pulping, and

20% for bleaching effluents by using alum as a

coagulant. Rohella et al. (2001) stated polyelectrolytes

were better than the conventional coagulant alum to

remove turbidity, COD, and color. Sheela and Distidar

(1989) reported on black liquor treatment by precipi-

tation with CaSO42H2O in the presence of CO2. Theremoval of dissolved solids was reported to be 63%.

However, Wang and Pan (1999) reported that the use

of coagulants such as polyethylene oxide (PEO),

worsened the settlability and increased COD levels,

turbidity, and suspended solids of the treated effluent

when the dose was between 25 and 250 ppm. Cher-

noberezhskii et al. (1994) reported that coagulation

with aluminum sulfate or modified adsorbents was the

best option for color removal from the sulfate and

sulfite wood pulp and paper industry.

6.1.3. Adsorption

Murthy et al. (1991) reported a high removal of

color by activated charcoal, fullers earth, and coal ash.

Shawwa et al. (2001) reported 90% removal of color,

COD, DOC, and AOX from bleached wastewater by

the adsorption process, using activated coke as an

adsorbent. Sullivan (1986) concluded that the waste-

water produced by the Union Camp Facility at Frank-

lin, VA, can be treated by activated carbon and ion

exchange to reduce color and chloride to levels ac-

ceptable for reuse. Das and Patnaik (2000) investigated

the lignin removal efficiency of the blast furnace dust

(BFD) and slag by the adsorption mechanism. Their

study showed 80.4% and 61% removal of lignin by

BFD and slag, respectively. Narbaitz et al. (1997)

reported that PACTk process was an effective processto remove AOX from the kraft mill effluent to meet

Ontarios year 2000 regulation (AOX: 0.8 kg Cl/adt of

production).

6.1.4. Chemical oxidation

Balcioglu and Ferhan (1999) reported on photo-

catalytic oxidation of kraft pulp bleaching wastewatershowing that the removal largely depended on the

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 375844concentration of COD and chloride below a certain

level. Zamora et al. (1998) reported on the use of

horseradish peroxide to decolorize kraft effluent by

50% within three hours of reaction time. The degra-

dation of phenolic and polyphenolic compounds pres-

ent in the bleaching effluent was studied using

advanced oxidation systems such as photocatalysis

with O2/ZnO/UV, O2/TiO2/UV, O3 and O3/UV. The

authors concluded that O2/ZnO/UV and O2/TiO2/UV

were the best systems to oxidize the effluent in a short

period of time. Perez et al. (2002c) reported that the

combination of Fenton and photo-fenton reactions

proved to be highly effective for the treatment of

bleaching kraft mill effluent. Verenich et al. (2000)

reported on the improvement in biodegradability of an

effluent from 30% to 70% by wet oxidation method.

Hassan and Hawkyard (2002) studied the removal of

color by combined oxidation with ozone and Fentons

reagent and stated that 100% color removal was

achieved at a pH of 45 in the case of ferral (derived

from natural clay sources, which contains 2% ferric

sulfate and 6% aluminum sulfate) and ferric sulfate.

Dufresne et al. (2000) reported on the oxidation of

total reduced sulfur (TRS) giving odor free products

by catalytically enhanced oxidation.

6.1.5. Membrane filtration

Jonsson et al. (1996) reported on the treatment of

paper coating color effluent treatment by membrane

filtration suggesting that the composition of the color

had a significant influence on the performance. Mem-

brane separation techniques were reported to be

suitable for removing AOX, COD, and color from

pulp and paper mills (Zaidi et al., 1992; Afonso and

Pinho, 1991, Falth, 2000). De Pinho et al. (2000)

compared the efficiency of (1) ultrafiltration and (2)

ultrafiltration plus dissolved air flotation. The results

showed 54%, 88%, 100% removal of TOC, color,

and SS, respectively by ultrafiltration alone. Ultrafil-

tration plus dissolved air flotation resulted in 65%,

90% and 100% removal of TOC, color, and SS,

respectively. Dube et al. (2000) reported that 88%

and 89% removal of BOD, and COD, respectively

was achieved by reverse osmosis (RO). Merrill et al.

(2001) stated that membrane filtration (MF), and

granular membrane filtration (GMF) were suitable

for removing heavy metals from the pulp and papermill wastewaters.6.1.6. Ozonation

Yeber et al. (1999) reported that a substantial

removal of COD, TOC, and toxicity from pulp mill

effluent and increased biodegradability of the effluent

were achieved after treatment with ozone. Korhonen

et al. (2000) reported a 90% removal of ethylenedia-

minetetraacetic acid (EDTA) and a 65% removal of

COD by ozone treatment of the pulp mill effluent.

Hinck et al. (1997) reported that neither EDTA nor

diethylene triamine pentaacetic acid (DTPA) are bio-

degraded in aerobic conditions. Oeller et al. (1997)

reported high removal of COD and DOC from the

pulp effluent by ozone treatment. Freire et al. (2000)

reported a 12% reduction of total organic carbon, total

phenols reduced to 70%, and effluent colors to 35% of

bleached pulp mill effluent after 60 min of ozonation.

Several authors reported on toxic compounds, COD,

and color removal by ozone treatment (Hostachy et

al., 1997; Zhou and Smith, 1997; Yamamoto, 2001).

Roy-Arcand and Archibald (1996) reported that bio-

treated kraft effluents yielded a substantial decrease in

the biologically recalcitrant residual adsorbable or-

ganic halogens (AOX), converted COD to BOD and

yielded large decrease in color. Laari et al. (2000)

investigated the removal of lipophilic wood extrac-

tives from TMP wastewater by ozonation. The authors

indicated that a high dosage of ozone (100300 mg/

dm3) was required to remove 50% of lippphilic wood

extractives. Korhonen and Tuhkanen (2000) reported

that ozone doses of 0.2 mgO3/initial mgCOD elimi-

nated over 90% resin acid. Torrades et al. (2001)

reported high removals of TOC, COD, AOX, and

color from bleached kraft mill effluent (BKME1)

using heterogeneous photocatalysis and ozone treat-

ment. Sevimli and Sarikaya (2002) reported a 95

97% color removal for high doses of ozone in 15 min

of ozonation. Kallas and Munter (1994) suggested

post treatment of bleached mill effluent by ozonation

and adsorption.

6.2. Biological treatment

6.2.1. Aerobic treatment

6.2.1.1. Activated sludge process. The performance

variation of the activated sludge due to the changes in

pH, temperature, and H2O2 and DTPA was reported

by Ginkel et al. (1999), Norris et al. (2000), and

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 45Larisch and Duff (1997, 2000), respectively. Knudsen

et al. (1994) reported a high reduction of BOD and

soluble COD by a two-stage activated sludge process.

Shere and Daly (1982) claimed that TMP wastewater

was readily degradable by the activated sludge pro-

cess. Hansen et al. (1999) suggested upgrading the

activated sludge plant by the addition of Floobeds

(floating biological bed) in series that increased COD

and BOD removal from 51% to 90% and 70% to

93%, respectively. Chandra (2001) reported efficient

removal of color, BOD, COD, phenolics, and sulfide

by microorganisms such as Pseudomonas putida,

Citrobacter sp., and Enterobacter sp. in the activated

sludge process. Mohamed et al. (1989) reported

removal of chlorinated phenols, 1,1-dichlorodimethyl

sulfone (DDS), and chlorinated acetic acids in an

oxygen activated sludge effluent treatment plant.

Demirbas et al. (1999) reported AOX removal by

the activated sludge process. Junna and Ruonala

(1991) reported 90% BOD7, 70% COD, 4060%

AOX, and 6095% chlorinated phenols removal by

the activated sludge process. Bryant et al. (1992)

reported AOX removal of 46% on average from

two activated sludge systems studied. Andreasan et

al. (1999) suggested the addition of an anoxic selector

before the activated sludge plant to improve the

sludge settlability problem. Raghuveer and Sastry

(1991) reported that a minimum of mixed liquor

suspended solids (MLSS) of 20002500 mg/l and

an aeration time of 68 h were required to remove

8388% of BOD. High removals of BOD, COD,

AOX, and chlorinated phenolics have been achieved

in the activated sludge process (Saunamaki, 1997;

Schnell et al., 2000a). Kennedy et al. (2000) reported

that the activated sludge was successful in removing

nearly all detectable Microtoxk toxicity frombleached kraft pulp mills at low level whereas the

PACTk was slightly better in removing highly toxicconcentrated effluents.

6.2.1.2. Aerated lagoons. Stuthridge and Mcfarlane

(1994) stated that 70% removal of the AOX from the

aerated lagoon was attributed to a short residence

time section of the treatment system where the

chlorinated stage effluents were mixed with general

mill wastewaters. The effect of simple mixing was

reported to be responsible for 1546% removal.Bryant et al. (1997) reported 67% removal of am-monia from black liquor spill at temperatures of 22

35 jC, pH near 7.3 in an aerated lagoon. Chernyshet al. (1992) reported large variations in AOX and

TOC removal in a controlled batch study of bleached

kraft effluent in an operating lagoon under both

aerobic and anaerobic conditions. Welander et al.

(1997) reported COD removal of 3040% in a full-

scale lagoon and 6070% in a pilot-scale plant.

Stuthridge et al. (1991) reported 65% removal of

AOX from bleached kraft pulp and paper mill

effluent. Junna and Ruonala (1991) reported removal

of BOD7 ranging between 50% and 75% and chlo-

rinated phenolics 1050% by an aerated lagoon.

Achoka (2002) reported that an oxidation pond

removed chemical compounds greater than 50%.

Schnell et al. (2000a) reported removals of BOD,

AOX, chlorinated phenolics, and polychlorinated

phenolics respectively from an aerated lagoon.

6.2.1.3. Aerobic biological reactors. Many authors

have reported high removals of organic pollutants of

kraft mill wastewater by sequencing batch reactor

(SBR) treatment (Franta et al., 1994; Franta and

Wilderer, 1997; Milet and Duff, 1998). Reid and

Simon (2000) reported 100% removal of methanol

and 90% removal of CODsol by SBR. Substantial

removal of COD, TOC, BOD (Magnus et al.,

2000a), lignin and resin acids (Magnus et al.,

2000b) of TMP wastewater using high rate compact

reactors (HCRs) at a retention time of 1.5 h had

been reported. Removal of COD by a moving bed

bifilm reactor (MBBR) had been demonstrated (Jah-

ren et al., 2002; Borch-Due et al., 1997). Magnus et

al. (2000c) reported 93% and 65% removal of BOD

and COD, respectively by a biological compact

reactor. Berube and Hall (2000) showed that approx-

imately 93% removal of TOC could be achieved by

a membrane bioreactor. Asselin et al. (2000) con-

cluded that suspended carrier biofilm reactor (SCBR)

was highly efficient in removing chronic toxicity

from the effluent. Rovel et al. (1994) achieved

76%, 62%, 81%, and 48% removal of BOD,

COD, SS, and AOX, respectively, using a biofilter.

Rudolfs and Amberg (1953) demonstrated that aer-

obic treatment of whitewater (high strength) was

able to achieve 7080% removal of BOD. Typical

efficiencies of aerobic systems are presented inTable 8.

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758466.2.2. Anaerobic treatment

An anaerobic process is considered more suitable

to treat high strength organic effluents. Before 1980s,

the treatment of pulp mill effluents by anaerobic

means was limited, as most of the pulp mill effluents

at that time were less concentrated (3002000 mg/

l BOD) (Bajpai, 2000) and were not suitable for

anaerobic treatment. Anaerobic filter, upflow sludge

blanket (UASB), fluidized bed, anaerobic lagoon, and

anaerobic contact reactors are anaerobic processes,

that are commonly used to treat pulp and paper mill

effluents. Pretreatment of the kraft mill black liquor

was investigated by Poggi-Varaldo et al. (1996) and

they reported that continuous anaerobic treatment of

wastewater contaminated with black liquor was fea-

sible at low to medium loading rates, with a total COD

removal of 4880% and biodegradable COD reduc-

tion of 8796%. Jahren et al. (1999) compared

anaerobic and aerobic treatment for TMP mill effluent

and found that 84% and 86% removal of COD from

anaerobic and aerobic treatment systems, respectively,

was achieved. Rajeshwari et al. (2000) reported that

chlorine bleaching effluents were not suitable for

anaerobic treatment due to their low biodegradability

Table 8

Typical efficiencies of aerobic systems (Springer, 2000; *Kantar-

djieff and Jones, 1997)

System Aeration

time (day)

Organic loading

(lb BOD/1000 ft3)

Efficiency

(%)

Aerobic biofilters

(sulfite mill)*

3.4 kg/m3/day 7492

Aerobic biofilters

(TMP)*

7490

Aerobic stabiliztion

basin

510 50 8090

Activated sludge 38 h 50 8085and presence of toxic substances that affects metha-

nogens. Sandquist and Sandstrom (2000) developed a

new treatment technology [the process consists of

three steps: (1) stripping of sulfides and other volatile

components from condensate; (2) regenerative ther-

mal oxidation of stripper off gases; (3) adsorption of

sulfur oxide] to treat foul condensate (sulfide) from

the black liquor. Removal efficiency for foul conden-

sate was reported to be more than 99% at a pH of 4

and removal of methanol was 90% at a low liquid/gas

ratio. Jackson-Moss et al. (1992) found 50% removal

of COD and color by anaerobic biological granularactivated carbon. Dufresne et al. (2001) observed that

undiluted foul condensates at Windsor mill were toxic

to anaerobic biomass. Chen and Horan (1998) stated

that COD, and sulfate removals of 66% and 73%,

respectively, were obtained using a UASB reactor

with a hydraulic retention time of 6 h. Peerbhoi

(2000) investigated anaerobic treatability of black

liquor by a UASB reactor in her study at the Univer-

sity of Roorkee, India. The author concluded that

anaerobic biological treatment of black liquor was

not feasible, as the pollutants were not readily de-

gradable. Perez et al. (1998) evaluated two anaerobic

systems (anaerobic filters and fluidized bed) in labo-

ratory-scale reactors and reported that 81.5% organic

removal efficiency was obtained in the case of fluid-

ized bed with porous packing and 50% removal was

obtained in the case of anaerobic filters on corrugated

plastic tubes. Rajeswori et al. (2000) reported a 50%

reduction of BOD of debarking wastewater by a

fluidized bed reactor. Thompson et al. (2001) reported

that COD removal efficiency of 80% was constantly

achievable but the residual COD was around 800 mg/

l meaning that additional treatment was essential.

Schnell et al. (1992) concluded that anaerobic treat-

ment systems were less suitable for treatment of

sulfite-spent liquor compared to an aerobic system.

The anaerobic treatability of different processes are

given in Table 9.

6.3. Fungal treatment

Taseli and Gokcay (1999) isolated fungal specie

(Pencillium sp.) which was able to remove 50% of the

AOX, and color from the soft-wood bleachery efflu-

ents in a contact time of 2 days. Several authors

reported on the capacity of different fungal species

to remove color from kraft mill effluent (Gokcay and

Dilek, 1994; Duran et al., 1994; Sakurai et al., 2001).

Prasad and Gupta (1997) reported on a substantial

reduction of color and COD by the use of white rot

fungi T. versicolor and P. chrysosporium. Saxena and

Gupta (1998) showed that white-rot fungi P. chrys-

osporium in combination with other white-rot fungi

(P. sanguineus, P. ostreatus and H. annosum) and with

the use of the surfactants were able to remove color,

COD, and lignin content. Choudhury et al. (1998)

found that lignin, BOD, COD and color removal wereachieved to the extent of 77%, 76.8%, 60%, and 80%,

Table 9

Anaerobic degradability of pulp and paper mill effluent (Rintala and Puhakka, 1994)

Wastewater from COD (mg/l) Anaerobic

degrad. (%)

Inhibitors

Wet debarking 13004100 4478 Resin acids

Thermomechanical

pulping

10005600 6087 Resin acids

Chemothermomechanical

pulping

250013,000 4060 Resin acids,

fatty acids, sulfur, DTPA

NSSC-spent liquor 40,000 nr Tannins

NSSC-condensate 7000 nr Sulfur, ammonia

Kraft condensate 100033,600 8392 Sulfur, resin acids,

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 47respectively, by the fungal specie Pleurotus ostreatus.

Zhang et al. (2000a) examined the removal of most of

the detrimental organics from whitewater by com-

bined enzyme and fungal treatment. The removal of

lignin was >90% whereas resin and fatty acids were

reduced by 20%. Zhang et al. (2000b) showed that

fungus such as T. versicolor and fungal culture filtrate

(FCF) obtained from these organisms were able to

efficiently degrade the dissolved and colloidal sub-

stances. Mendonca et al. (2002) suggested fungal

pretreatment of P. taeda wood chips by C. subvermis-

pora. The performance of fungal treatment is summa-

rized in Table 10.

Spent condensate 750050,000

Chlorine bleaching 9002000

Sulfite spent liquor 120,000220,0006.4. Integrated treatment processes

An integrated or hybrid system is designed to take

advantage of unique features of two or more process-

es. A combination of coagulation and wet oxidation

removed 51% of COD (Verenich et al., 2001); and

Table 10

Performance of fungal treatment

Treatment process Parameters

COD Lignin

Influent

(mg/l)

%

Removal

Influent

(mg/l)

White rot fungi 39,012 40.74 2870

White rot + surfactants 39,012 75.35 2870

White rot (T. versicolor) 77.7

White rot (P. chrysosporium) 79.4 83% of color and 75% of lignin (Verenich and Kallas,

2001). A combination of ozone and biofilm reactor

removed 80% COD (Helble et al., 1999). A combi-

nation of chemical oxidation with ozone removed

90% of wood extractives and 50% of the COD from

TMP wastewater at 150 jC (Laari et al., 1999).Athanasopoulos (2001) suggested post treatment

methods such as electrolysis or ozonation to reduce

COD, and NH4+N concentration to the permitted

level. Nakamura et al. (1997) reported on efficient

degradation of lignin using a combined treatment of

ozone and activated sludge process. Jokela and Keski-

talo (1999) reported that a combination of dissolved

air flotation and chemical precipitation removed 93%

fatty acids, terpenes

5090 Sulfur, organic sulfur

3050 Chlorinated phenols,

resin acids

nr nrSS, 50% BOD7, 57% COD, 92% phosphorus, and

52% nitrogen.

A combination of activated sludge and with

ozonation (as tertiary treatment) removed 8797%

COD, and 97% BOD (Schmidt and Lange, 2000).

Kabdash et al. (1996) showed that a combination of

Reference

Color

%

Removal

Influent

(mg/l)

%

Removal

16.38 34,940 34.49 Saxena and Gupta (1998)

65.84 34,940 81.29 Saxena and Gupta (1998)

1875 93.8 Prasad and Gupta (1997)

1875 83.5 Prasad and Gupta (1997)

Table 11

Performance of physicochemical treatment processes

Treatment process Parameters Reference

TSS COD TOC AOX Color Lignin/Resin*

or Fatty# acid

Influent

(mg/l)

%

Removal

Influent

(mg/l)

%

Removal

Influent

(mg/l)

%

Removal

Influent

(mg/l)

%

Removal

Influent

(PtCo)

%

Removal

Influent

(mg/l)

%

Removal

Coagulation:

Polyelectrolyte 3620 100 4112 55.65 4667.5 82.58 480 98.91 Rohella et al. (2001)

Chitosan 70 90 Ganjidoust et al. (1997)

PE/PEI 30 80 Ganjidoust et al. (1997)

Alum 40 80 Ganjidoust et al. (1997)

Adsorption:

Charcoal #1 3.9 mg/l 98.13 Murthy et al. (1991)

Coal ash #2 3.9 mg/l 98.5 Murthy et al. (1991)

Fuller earth #3 3.9 mg/l 99.21 Murthy et al. (1991)

Activated coke #4 2126 >90 80.2 >90 2300 >90 Shawwa et al. (2001)

Oxidation:

(Wet oxidation)

10,000~19,000 80 3500~4100 80 Verenich et al. (2000)

(Ozone + Fenton) ~100 Hassan and

Hawkyard (2002)

Ozonation:

Ozone +UV ~550 82 Oeller et al. (1997)

Photocat. + ozone 515 85 306 88 27.7 92.5 250 100 Torrades et al. (2001)

Photocat. + ozone 3700 57.5 1380 38 69.8 50 7030 65 Torrades et al. (2001)

Membrane:

Ultrafiltrtion 8590 8591 9398 Zaidi et al. (1992)

Nanofiltration 9396 99.299.9 Zaidi et al. (1992)

Dissolved air +UF 397 100 828 65 1747 90 De Pinho et al. (2000)

Microfiltration +UF 397 100 828 54 1747 88 De Pinho et al. (2000)

(#1) Charcoal dose 0.4 g/l and pH 2.0; (#2) Coal ash dose 12 g/l and pH 2.0; (#3) Fuller earth dose 4 g/l and pH 2.0; (#4) activated coke dose 15,000 mg/l.

D.Pokhrel,

T.Vira

raghavan/Scien

ceoftheTotalEnviro

nment333(2004)3758

48

Table 12

Performance of aerobic biological treatment processes

Treatment process Parameters Reference

TSS BOD COD AOX Chlorinated phenolics

Influent

(mg/l)

%

Removal

Influent

(mg/l)

%

Removal

Influent

(mg/l)

%

Removal

Influent

(mg/l)

%

Removal

Influent

(mg/l)

%

Removal

Activated sludge

Paper mill 1435 90.6 512 94.2 1210 82.4 Saunamaki (1997)

Pulp mill 738 76.4 336 93.8* 1192 57.1 11.7 55 Saunamaki (1997)

Kraft mill

(period 1)

270 >95* 660 (F) 60 22.5 36 0.255 74 Schnell et al.

(2000a)

(period 2) 270 >98 660 (F) 70 22.5 40 0.255 83 Schnell et al.

(2000a)

Pulp and

paper mill

96.63 96.8 96.92 Chandra (2001)

Paper mill 1000 99 1533a 85 Knudsen et al.

(1994)

62

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 49Aerobic stabilization basin

Kraft mill

(period 1)

270 >95 660 (F)chemical and biological methods (bioferic) resulted

in 4050% additional removal of COD compared to

the activated sludge system. Jahren and Oedegaard

(period 2) 270 >98 660 (F) 73

Kraft mill 206

(1) F means fraction of COD or soluble COD.

(2) Period 1: operating conditions for activated sludge-HRT 2 days, SRT

(3) Period 1: operating conditions for aerated stabilization basin-HRT 15

(4) Period 2: operating conditions for activated sludge-HRT 1 day, SRT 2

(5) Period 2: operating conditions for aerated stabilization basin-HRT 15a Means soluble COD and * means BOD7.

Table 13

Performance of biological treatment processes

Treatment process Parameters

BOD COD Metha

Influent

(mg/l)

%

Removal

Influent

(mg/l)

%

Removal

Influe

(mg/l)

Biological reactors

HRC (TMP Mill) 1150 98 3340 79

Total plant

efficiency

1490 99 5000 86

MBBR

(HRT 4.5 hrs)

6575 8595

SBR 98 8593

Anaerobic (GAC) 1400 50

Kraft mill Windsor 1429a 69 2036a 59 1095a

a Unit in g/d.22.5 53 0.255 85 Schnell et al.

(2000a)(1999) found that Kaldnes (anaerobic followed by

aerobic) moving bed biofilm reactor at 55 jC re-moved about 60% of soluble COD from TMP

22.5 55 0.255 86 Schnell et al.

(2000a)

5 1770 Chernysh et al.

(1992)

25 days, Temp. 30 jC, VSS 1800 mg/l.days, SRT 15 days, Temp. 30 jC, VSS 60 mg/l.5 days, Temp. 30 jC, VSS 2800 mg/l.days, SRT 15 days, Temp. 20 jC, VSS 70 mg/l.

Reference

nol Color

nt %

Removal

Influent

(mg/l)

%

Removal

Magnus et al. (2000a)

Magnus et al. (2000a)

Borch-Due et al. (1997)

Franta and Wilderer (1997)

1300 50 Jackson-Moss et al. (1992)

84 Dufresne et al. (2001)

whitewater. A combined anaerobicaerobic treat-

ment system was suggested to treat bleached kraft

pulp and paper mill effluents (Duncan and Thia,

1992; Wang et al., 1997). Lescot and Jappinen

(1994) showed that a combination of an aerated

lagoon and a secondary clarifier was able to treat

bleached kraft mill effluent in Finland resulting in

87%, 96%, 65%, 53%, and 22% removal of SS,

BOD7, COD, AOX, and color, respectively. Carlson

et al. (2000) reported that 77%, 9899%, 72%, and

81% removal of COD, BOD, TN, and TP, respec-

tively, was achieved after upgrading the aerated

basin at Monsteras mill. The system comprised of

an anoxic selector, an aerated basin, and a secondary

clarifier in series. The removals of extractives, resin

and fatty acids were 96% and 98%, respectively,

whereas the system reduced Microtoxk by 99%.Welander et al. (2000) reported on the performance

of an aerobic biological process called LSP (low

sludge production) to lower the biological sludge by

8090%. The system configuration was primary

clarifier, aeration basin, and secondary clarifier. A

combination of physicochemical, biological, and ef-

fluent polishing in the aerated lagoon removed 98

Table 14

Selected anaerobic process performance (Bajpai, 2000)

Mill location Wastewater source Loading rate

(kg COD/m3/d)

BOD5(mg/l)

COD

(mg/l)

TSS

(mg/l)

BOD5Removal%

COD

Removal%

Anaerobic contact reactor

Hylte Bruk

AB, Sweden

TMP,

groundwood, deink

2.5 1300 3500 520 71 67

SAICA,

Zaragoza, Spain

Waste paper alkaline

cooked straw

4.8 10,000 30,000 94 66

Hannover paper,

Alfred, Germany

Sulfite effluent

condensate

4.2 3000 6000 97 85

Niagara of Wisconsin

of USA

CTMP 2.7 2500 4800 3300 96 77

SCA Ostrand,

Ostrand, Sweden

CTMP 6 3700 7900 50 40

Alaska Pulp

Corporation, Sitka

Sulfite condensate,

bleach caustic and

pulp whitewater

3 3500 10,000 85 49

Upflow anaerobic sludge blanket

Celtona, Holland Tissue 3 600 1200 75 60

Southern paper

converter, Australia

Wastepaper 10 10,000 > 80 > 80

9

12.

18

20

13.

15

12.

35

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 375850Davidson,

United Kingdom

Linerboard

Chimicadel,

Friulli, Italy

Sulfite

condensate

Quesnel River

Pulp, Canada

TMP/CTMP

Lake Utopia

Paper, Canada

NSSC

EnsoGutzeit, Finland Bleached

TMP/CTMP

McMillan Bloedel,

Canada

NSSC/CTMP

Anaerobic filter:

Lanaken, Belgium

CTMP

Anaerobic fluidized Paperboardbed: D Aubigne, France1440 2880 90 75

5 12,000 15,600 90 80

3000 7800 60 50

6000 16,000 80 55

5 1800 4000 75 60

7000 17,500 80 55

7 4000 7900 85 70

1500 3000 83.3 72.2

7077%, and 8094% removal of BOD, COD, and

resin and fatty acids was provided by biological

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 51treatment. Tardif and Hall (1997) reported 100%,

96%, 76%, and 34% removal of resin acid (RA),

fatty acid (FA), dissolved chemical oxygen demand

(DCOD), and total dissolved solids (TDS), respec-

tively at temperatures 2040 jC by an SBR. AnMBR removed 100% RA and FA, 84% DCOD, and

37% TDS at 4050 jC. Malmquist et al. (1999)reported a COD removal of 7090% of whitewater

by biological treatment. Badar (1996) suggested a

number of methods to improve the integrated paper

mill wastewater effluent treatment: (1) increasing the

capacity of the aeration basin; (2) installing an extra

dissolved air flotation clarifier; (3) adding chlorine

gas to improve bulking of sludge problem and (4)

injecting oxygen to treat BOD during heavy rain and

flooded conditions. Graves and Joyce (1994)

reviewed the ability of biological treatment systems

to remove chlorinated organic compounds discharged

from pulp and paper industry. AOX removal of 32%

(aerated lagoon) and 1065% by activated sludge

plant was reported. Gupta et al. (2001) isolated

bacterial specie Aeromonas formicans suitable to

treat black liquor from kraft pulp and paper mills.

Performances of various treatment processes are

summarized in Tables 1114.

7. Discussion

The literature review showed that an internal

process change is one of the options to be adopted

by the pulp and paper industry to reduce the pollution

at the source. A recent comprehensive study carried

out in a large number of pulp and paper mills in the

US found that the effluent discharge has been reduced

by 30%; TSS and BOD have been reduced by 45%99% BOD, 91% COD, 97% SS, and 90% color of a

pulp and paper mill in Brazil (Foelkel, 1989). Rusten

et al. (1994) reported that a combination of a biofilm

reactor followed by one anaerobic and two aerobic

reactors was found to remove 50% COD, 8090%

BOD7, 50% AOX, 90% ClO3. Shaw et al. (2002)

showed that a combination of aerobic reactor fol-

lowed by anaerobic reactor removed 94% color, and

66% TOC. Schnell et al. (1997) found that 8795%,and 75%, respectively (Das and Jain, 2001) evenwhen the production has been increased. Trotter

(1990a,b) evaluated biotechnological applications

such as genetic modification of plant, biopulping,

and biobleaching to reduce chlorinated organic com-

pounds as an emerging technology for internal pollu-

tion control. Enzyme treatment for pulp dissolving,

improving tensile properties by treating mechanical

pulp with white rot organisms and enzymatic beating

of chemical pulps, hemicellulose, and decolorization

by white rot fungi were given as possible biotechno-

logical options.

Among the various treatment processes currently

used for pulp and paper effluent treatment, only a few

are commonly adopted by pulp and paper industry

especially for tertiary treatment. Some of the treatment

processes such as ozonation, fentons reagent, adsorp-

tion, and membrane technology are efficient but are

more expensive. Sedimentation is the most commonly

adopted process by the pulp and paper industry to

remove suspended solids. The performance data given

by Springer (2000) showed 8090% removal of

initial suspended solids from most of the mills except

a deinking mill. Flotation is also commonly used in

the pulp and paper industry but most of the time as a

tertiary treatment. Coagulants are a preferred option

for removing turbidity and color from the wastewater.

Reported results have shown that they are also capable

in reducing COD, TOC, and AOX to some extent.

Among the coagulants, modified chitosan showed the

highest performance for color and TOC removal.

Polyelectrolytes are better than alum and they produce

less sludge and pose less problems with sludge

dewaterability than alum. Adsorption processes are

useful to remove color, COD, and AOX. They are

rather expensive and it is not known whether the pulp

and paper industry are employing them widely. How-

ever, laboratory-scale experiments are usually

reported. Activated charcoal, fullers earth, and coal

ash showed better results for color removal. Activated

coke alone was able to remove 90% of the COD,

AOX, DOC, and color.

Chemical oxidants such as ozone + photocatalysis,

and ozone + UV are reported to be efficient in

removing COD and TOC and color. However, the

efficiency largely depends upon the concentration of

the COD. Ozone alone is able to remove 90% of

EDTA and AOX, and over 80% of COD. However,it is rather expensive (Perez et al., 2002b). Ozonation

ious authors lead to a better understanding of the

various treatment processes and their adaptability.

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 375852is not commonly adopted in most countries, not even

in Europe but it is emerging in North America.

Membrane processes are efficient in reducing over

90% of color, TSS, and AOX in most of the cases.

Fouling of membranes is a problem in the case of

soft wood effluent treated by membrane filtration. In

secondary treatment processes, activated sludge is

the most commonly used. UASB and fluidized beds

are also gaining in use recently. The problem with

activated sludge is sludge bulking. Reported results

have shown that activated sludge can remove all

types of the pollutants pertaining to the pulp and

paper industry. However, the removal of AOX is

below 50%, BOD around 95% in most of the mills,

and COD removal averages around 70%. This sys-

tem is also efficient in removing chlorinated phenolic

compounds (over 75%) most of the time. Dalentoft

and Thulin (1997) reported that Kaldnes (anaero-

bic + aerobic) process in series with an activated

sludge, could be an efficient, stable, and a compet-

itive combination process, considering both invest-

ment and operating costs. Aerated lagoons are

efficient in removing BOD over 95% in most of

the reported results. COD removals are moderate

between 60% and 70%, AOX around 50%, and a

high removal (85%) for chlorinated phenolics. An-

aerobic contact reactors are efficient in removing

biodegradable organic compounds such as BOD,

and COD. The performance data from various mills

showed that anaerobic contact reactors were able to

remove over 90% of BOD and 65% of COD in most

of the cases. Anaerobic filters and fluidized bed

reactors are suitable in reducing organic pollutants

only. Both the reactors achieve almost same efficien-

cy in terms of BOD (>80%), and COD (>70%)

removal (refer to Table 14 for details). UASBs are

able to remove over 80% of BOD and 5080% of

COD in most of the mills (refer to Table 14 for

details). Fungi are efficient in removing especially

color and COD from the pulp mill wastewater.

Removal of color using white rot fungi was above

80% in most of the reported cases and COD removal

was above 75%. White rot fungi particularly P.

chrysosporium and C. versicolor are suitable for

efficient degradation of the refractory material (Baj-

pai and Bajpai, 1994). The reported results have

shown that high removals are achieved in the caseof the combination of two or more physicochemicalFor example, Jemaa et al. (2000) stated that chemical

precipitation, evaporation, membrane technology, and

ion exchange were the established options for the

removal of colloids and metal ions. Perez et al.

(2002a) conducted an economic evaluation of various

advanced oxidation processes to remove organic con-

taminants. Ozonation was stated to be effective but

rather an expensive process. Rintala and Puhakka

(1994) stated that operation costs of the activated

sludge was about three times greater than that of

anaerobic systems. Bajpai (2000) presented compara-

tive costs of the anaerobic and activated sludge treat-

ment, which showed that activated sludge was almost

twice as expensive as anaerobic reactors. The recent

paper by Perez et al. (2002b) reported a high efficiency

of COD and TOC removal when iron ion was used

with ozone/UV treatment system. The authors showed

that the presence of iron ion in the ozone/UV treatment

brought a complete removal of COD in 90 min while

TOC removal was higher than 90%. The report stated

that the overall cost was reduced by 50%, which is

encouraging news for the industry. Mobius and

Cordes-Tolle (1994) suggested that sand filters, bio-

filters, low capacity trickling filters, flocculation and

precipitation with inorganic salts in combination with

filtration or flotation are the emerging systems for

adoption by pulp and paper mills.

8. Conclusions

Based on the above literature review, the following

conclusions are drawn:

(i) Both aerobic and anaerobic treatment systems

are feasible to treat wastewater from all types

of pulp and paper mills except that bleachingprocesses or combination of physicochemical and

biological processes. The confirmation of the reported

results, their applicability in the real field, and eco-

nomic evaluations are very important in adopting the

process. For example, the anaerobic treatment process

for pulp and paper mill effluents is still in an initial

application phase.

However, comprehensive evaluations made by var-kraft effluents are less suitable for treatment by

pulp and paper mill effluent treatment.

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 53(viii) More studies are needed on the removal of

AOX and chlorinated phenolic compounds.

References

Achoka JD. The efficiency of oxidation ponds at the kraft pulp

and paper mill at Webuye in Kenya. Water Res 2002;36:

120312.

Afonso MD, Pinho MN. Membrane separation processes in pulp

and paper production. Filtr Sep 1991;28(1):424.

Andreasan K, Agertved J, Petersen JO, Skaarup H. Improvement

of sludge settleability in activated sludge plants treating efflu-

ent from pulp and paper industries. Water Sci Technol 1999;

40(1112):21521.

Archibald F. The presence of coliform bacteria in Canadian pulp

and paper mill water systemsa cause for concern? Water Qual

Res J Can 2000;35(1):122.

Asselin C, Collin D, Graff S. Effluent treatment for chronic toxicity

removal with the suspended carrier biofilm reactor. Tappi Inter-

national Environmental Conference and Exhibit. Denver CO,

vol. 2. Norcross, GA 30092, USA: Technical Association for

Pulp and Paper Industry (TAPPI); May 2000. p. 80511.

Athanasopoulos NS. Use of various processes for pilot plant treat-

ment of wastewater from a wood processing factory. J Chem

Technol Biotechnol 2001;76:24650.

Azevedo MAD, Drelich J, Miller JD. The effect of pH on pulping

and flotation of mixed office wastepaper. J Pulp Pap Sci 1999;

25(9):31730.anaerobic means, as they are more toxic to

anaerobic bacteria.

(ii) The anaerobic treatment of high strength

wastewater requires further treatment as it

contains high residual COD.

(iii) A combination using an anaerobic process

followed by an aerobic treatment system is a

better option, as it can make use of the

advantages of both the treatment processes.

(iv) Color is removed efficiently by fungal treat-

ment, coagulation, chemical oxidation, and

ozonation.

(v) Chlorinated phenolic compounds and AOX can

be removed by adsorption, ozonation and

membrane filtration.

(vi) Combinations of two or more physicochemical

processes produce a high removal of toxic

pollutants.

(vii) Combinations of physicochemical and biolog-

ical treatment processes with optimization of

the process provide a long-term solution forBadar TA. Wastewater treatment at pulp and paper mills effluent

compliance improvements at a newsprint facility. Asia Pac Tech

Monit 1996;13(6):813.

Bajpai P. Treatment of pulp and paper mill effluents with anaerobic

technology. Randalls Road, Leatherhead, UK: Pira International;

2000.

Bajpai P, Bajpai PK. Biological colour removal of pulp and paper

mill wastewaters. J Biotechnol 1994;33:21120.

Balcioglu AI, Ferhan C. Treatability of kraft pulp bleaching waste-

water by biochemical and photocatalytic oxidation. Water Sci

Technol 1999;40(1):2818.

Baruah BK. Effect of paper mill effluent on plankton population of

wetland. Environ Ecol 1997;15(4):7707.

Berube PR, Hall ER. Fate and removal kinetics of contaminants

contained in the evaporator condensate during treatment for

reuse using a high temperature membrane bioreactor. Proc.

86th PAPTAC annual meeting, Montreal, Quebec. Canada: Pulp

and Paper Technical Association of Canada; 2000. p. B67.

Berube PR, Kahmark KA. Pulp and paper mill effluents. Water

Environ Res 2001;73(5):136.

Borch-Due A, Anderson R, Opheim B. Treatment of integrated

newsprint mill wastewater in moving bed biofilm reactors. Wa-

ter Sci Technol 1997;35(23):17380.

Bryant CW, Avenell JJ, Barkley WA, Thut RN. The removal of

chlorinated organics from conventional pulp and paper waste-

water treatment systems. Water Sci Technol 1992;26(12):

41725.

Bryant CW, Barkley WA, Garett RM, Gardner FD. Biological ni-

trification of kraft wastewater. Water Sci Technol 1997;35(23):

14753.

Carlson B-L, Ericsson T, Loyblad R, Persson S, Simon O. The

reconstruction of an aerated lagoon to a long-term aerated sludge

(LAS) plant at Sodra cell, Monsteras kraft pulp mill. Tappi

International Environmental Conference and Exhibit, Denver,

CO, vol. 1. Norcross, GA 30092, USA: Technical Association

for Pulp and Paper Industry (TAPPI); 2000. p. 36371.

Chandra R. Microbial decolourisation of pulp mill effluent in pres-

ence of nitrogen and phosphorous by activated sludge process. J

Environ Biol 2001;22(1):237.

Chen W, Horan NJ. The treatment of a high strength pulp and paper

mill effluent for wastewater re-use (II) biological sulphate re-

moval from effluent with a low COD/sulphate ratio. Environ

Technol 1998;19:16371.

Chernoberezhskii YuM, Dyagileava AS, Barysheva IA. Coagula-

tion treatment of wastewaters from paper and pulp plants. Russ J

Appl Chem 1994;67(3):3549.

Chernysh A, Liss NS, Allen GD. A batch study of the aerobic and

anaerobic removal of chlorinated organic compounds in an aer-

ated lagoon. Water Pollut Res J Can 1992;27(3):62138.

Choudhury S, Sahoo N, Manthan M, Rohela RS. Fungal treatment

of pulp and paper mill effluents for pollution control. J Ind

Pollut Control 1998;14(1):113.

Dalentoft E, Thulin P. The use of the kaldnes suspended carrier

process in treatment of wastewaters from the forest industry.

Water Sci Technol 1997;35(23):12330.

Das KT, Jain AK. Pollution prevention advances in pulp and paper

processing. Environ Prog 2001;20(1):8792.

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 375854Das CP, Patnaik LN. Removal of lignin by industrial solid wastes.

Pract Period Hazard, Toxic, Radioact Waste Manag 2000;

4(4):15661.

Demirbas G, Gokcay CF, Dilek FB. Treatment of organic chlorine

in pulping effluents by activated sludge. Water Sci Technol

1999;40(1):2759.

De Pinho MN, Minhalma M, Rosa MJ, Taborda F. Integration of

flotation/ultrafiltration for treatment of bleached pulp effluent.

Pulp Pap Can 2000;104(4):504.

Dey A, Sarkar D, Sengupta B, Banerjee S. Wastewater treatment in

pulp and paper industry-trend and practices. Indian J Environ

Prot 1991;11(12):899905.

Dilek FB, Gokcay CF. Treatment of effluents from hemp-based

pulp and paper industry: waste characterization and physico-

chemical treatability. Water Sci Technol 1994;29(9):1613.

Dsurney SJ, Eddy LP, Felder DP, Rodgers JH, Deardorff TL.

Assesment of the impact of a bleached kraft mill effluent on a

south-central USA river. Environ Toxicol 2002;15(1):2839.

Dube M, McLean R, MacLatchy D, Savage P. Reverse osmosis

treatment: effects on effluent quality. Pulp Pap Can 2000;

101(8):425.

Dufresne R, Caouette L, Norval GW, Kanters CJ. Treat-

ment of clean condensate using catalytically enhanced oxida-

tion. Proc. 86th PAPTAC annual meeting, Montreal, Quebec.

Canada: Pulp and Paper Technical Association of Canada;

2000. p. A257.

Dufresne R, Liard A, Blum SM.Anaerobic treatment of condensates:

at a kraft pulp and paper mill. Water Environ Res 2001;73(1):

1039.

Duncan A, Thia B. Treatment of pulp and paper mill effluent. Aust

Biotechnol 1992;2(4):235.

Duran N, Esposito E, Innicentini-Mei LH, Canhos PV. A new al-

ternative process for kraft E1 effluent treatment. Biodegradation

1994;5:139.

Dutta SK. Study of the physicochemical properties of effluent of the

paper mill that affected the paddy plants. J Environ Pollut

1999;6(2 and 3):1818.

Erisction G, Larsson A. DNA A dots in perch (Perca fluviatillis) in

coastal water pollution with bleachen in pulp mill effluents.

Ecotoxicol Environ Saf 2000;46:16773.

Falth F. Ultrafiltration of E1 stage effluent for partial closure of

the bleach plant. Proc. 86th PAPTAC annual meeting, Mon-

treal, Quebec. Canada: Pulp and Paper Technical Association

of Canada; 2000. p. B85.

Felder DP, Dsurney SJ, Rodgers JH, Deardorff TL. A comprehen-

sive environmental assessment of a receiving aquatic system

near an unbleached kraft mill. Ecotoxicology 1998;7:31324.

Foelkel C. Advanced waste treatment. Pulp Pap 1989;63(4):1734.

Franta JR, Wilderer PA. Biological treatment of papermill waste-

water by sequencing batch reactor technology to reduce residual

organics. Water Sci Technol 1997;35(1):12936.

Franta J, Helmreich B, Pribyl M, Adamietz E, Wilderer PA.

Advanced biological treatment of papermill wastewaters; effects

of operating conditions on COD removal and production of sol-

uble organic compounds in activated sludge systems. Water Sci

Technol 1994;30(3):199207.

Freire RS, Kunz A, Duran N. Some chemical and toxicologicalaspects about paper mill effluent treatment with ozone. Environ

Technol 2000;21:71721.

Ganjidoust H, Tatsumi K, Yamagishi T, Gholian RN. Effect of syn-

thetic and natural coagulant on lignin removal from pulp and

paper waste water. Water Sci Technol 1997;35(23):2916.

Ginkel GCV, Virtapohja J, Steyaert JAG, Alen R. Treatment of

EDTA-containing pulp and paper will wastewaters in activated

sludge plants. Tappi J 1999;82(2):13842.

Gokcay FC, Dilek FB. Treatment of effluents from hemp-based

pulp and paper industry (2) biological treatability of pulping

effluents. Water Sci Technol 1994;29(9):1658.

Graves JW, Joyce TW. A critical review of the ability of biological

treatment systems to remove chlorinated organics discharged by

the paper industry. Water SA 1994;20(2):15560.

Gubelt G, Lumpe C, Joore L. Towards zero liquid effluents at

Niederauer Muhlethe validation of two noval separation tech-

nologies. Pap Technol (UK) 2000;41(8):418.

Gune NV. Total water management in pulp and paper industry with

focus on achieving zero effluent discharge status. IPPTA J

2000;12(4):13742.

Gupta A. Pollution load of paper mill effluent and its impact on

biological environment. J Ecotoxicol Environ Monit 1997;7(2):

10112.

Gupta VK, Minocha AK, Jain N. Batch and continuous studied on

treatment of pulp mill wastewater by aeromonas formicans. J

Chem Technol Biotechnol 2001;76:54752.

Hansen E, Zadura L, Frankowski S, Wachowicz M. Upgrading of an

activated sludge plant with floating biofilm carriers at Frant-

schach Swiecie S.A. to meet the new demands of year 2000.

Water Science and Technology 1999;40(1112):20714.

Hassan MM, Hawkyard CJ. Decolourisation of aqueous dyes by

sequential oxidation treatment with ozone and Fentons

reagent. Journal of Chemical Technology and Biotechnology

2002;77:83441.

Helble A, Schalyer W, Liechti PA, Jenny R, Christian MH. Ad-

vanced effluent treatment in the pulp and paper industry with a

combined process of ozonation and fixed bed biofilm reactors.

Water Sci Technol 1999;40(1112):34350.

Hinck ML, Ferguson J, Puhaakka J. Resistance of EDTA and DPTA

to aerobic biodegradation. Water Sci Technol 1997;35(23):

2531.

Holmbom B, Harju L, Lindholm J, Groning AL. Effect of a pulp

and paper mill on metal concentration in the receiving lake

system. Aqua Fenn 1994;24(1):93110.

Hostachy JC, Lenon G, Pisicchio JL, Coste S, Lgeay C. Reduction

of pulp and paper mill pollution by ozone treatment. Water Sci

Technol 1997;35(23):2618.

Howe J, Michael RW. Effects of pulp mill effluent irrigation on the

distribution of elements in the profile of an arid region soil.

Environ Pollut 1998;105:12935.

Jackson-Moss CA, Maree JP, Wotton SC. Treatment of bleach plant

effluent with the biological granular activated carbon process.

Water Sci Technol 1992;26(12):42734.

Jahren SJ, Oedegaard H. Treatment of thermomechanical pulping

(TMP) whitewater in termophilic (55 (C) anaerobicaerobic

moving bed biofilm reactors. Water Sci Technol 1999;40(8):

8190.

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 55Jahren SJ, Rintala JA, Odegaard H. Evaluation of internal thermo-

philic biotreatment as a strategy in TMP mill closure. Tappi J

1999;82(8):1419.

Jahren JS, Rintala JA, Odegaard H. Aerobic moving bed biofilm

reactor treating thermomechanical pulping whitewater under

thermophilic conditions. Water Research 2002;36:106775.

Jemaa N, Thompson R, Paleologou M, Berry RM. Non-process

elements in the kraft recovery cycle, Part II: control and removal

options. Pulp and Paper Canada 2000;101(2):416.

Johnsen K, Tana J, Lehtinen K-J, Stuthridge T, Mattsson K, Hem-

ming J, Carlberg GE. Experimental field exposure of brown

trout to river receiving effluent from an integrated news-

print mill. Ecotoxicology and Environmental Safety 1998;40:

18493.

Jokela P, Keskitalo P. Plywood mill water system closure by dis-

solved air floatation treatment. Water Science and Technology

1999;40(1112):3341.

Jonsson AS, Jonsson C, Teppler M, Tomani P, Wannstrom S. Treat-

ments of paper coating colour effluents by membrane filtration.

Desalination 1996;105:26376.

Junna J, Ruonala S. Trends and guidelines in water pollution con-

trol in the Finnish pulp and paper industry. Tappi J 1991;

74(7):10511.

Kabdash I, Tunay O, Eldem N. Treatability of wastepaper pulping

process wastewater. Proceedings of the Industrial Waste Confer-

ence, West Lefayette, USA, vol. 51. Chelsea, Michigan 68118,

USA: Ann Arbor Press Inc.; 1996. p. 64550.

Kahmark KA, Unwin JP. Pulp and paper effluent management.

Water Environ Res 1996;68(4):551.

Kahmark KA, Unwin JP. Pulp and paper effluent management.

Water Environ Res 1998;70(4):667.

Kahmark KA, Unwin JP. Pulp and paper effluent management.

Water Environ Res 1999;71(5):836.

Kallas J, Munter R. Post-treatement of pulp and paper industry

wastewaters using oxidation and adsorption processes. Water

Sci Technol 1994;29(56):25971.

Kantardjieff A, Jones JP. Practical experiences with aerobic biofil-

ters in TMP sulfite and fine paper mills in Canada. Water Sci

Technol 1997;35(23):22734.

Kennedy KJ, Graham B, Droste RL, Fernandes L, Narbaitz R.

Microtox and Ceriodaphnia dubia toxicity of BKME with

powdered activated carbon treatment. Water SA 2000;26(2):

20516.

King HM, Baldwin DS, Rees GN, Mcdonald S. Apparent bio-

accumulation of Mn derived from paper-mill effluent by the

freshwater crayfish cherax destructorthe role of Mn oxidis-

ing bacteria. Sci Total Environ 1999;226:2617.

Knudsen L, Pedersen JA, Munck J. Advanced treatment of paper

mill effluents by a two-stage activated sludge process. Water Sci

Technol 1994;30(3):17381.

Korhonen S, Tuhkanen T. Effects of ozone on resin acids in ther-

momechanical pulp and paper mill circulation waters. Ozone:

Sci Eng 2000;22(6):57584.

Korhonen SM, Metsarinne SE, Tuhakanen TA. Removal of eth-

ylenediaminenetraacetic acid (EDTA) from pulp mill effluents

by ozonation. Ozone: Sci Eng 2000;22:27986.

Kovacs TG, Martel PH, Voss RH. Assessing the biological status offish in a river receiving pulp and paper mill effluents. Environ

Pollut 2002;118:12340.

Laari A, Korhonen S, Tuhkanen T, Verenich S, Kallas J. Ozonation

and wet oxidation in the treatment of thermomechanical pulp

(TMP) circulation waters. Water Sci Technol 1999;40(1112):

518.

Laari A, Korhonen S, Kallas J, Tuhkanen T. Selective removal of

lipophilic wood extractives from paper mill water circulations

by ozonation. Ozone: Sci Eng 2000;22:585605.

Larisch BC, Duff JB. Effect of H2 O2 and data on the character-

istics and treatment of TCF (totally chlorine-free) and ECF

(elementally chlorine-free) kraft pulping effluents. Water Sci

Technol 1997;35(23):16371.

Larisch BC, Duff JB. Effect of DTPA and EDTA on activated

sludge reactors treating bleached kraft mill effluent. Tappi J

2000;83(6):54.

Leppanen H, Oikari A. Occurrence of retene and resin acids in

sediments and fish bile from lake receiving pulp and a

paper mill effluents. Environ Toxicol Chem 1999;18(7):

1498505.

Lescot JC, Jappinen H. Effluent treatment in pulp and paper mills:

present technology and development trends. Appita J 1994;

47(4):3302.

Lindstrom-Seppa P, Hunskonen S, Kotelevtsev S, Mikkelson P, Ran-

nen T, Stepanova L, et al. Toxicity and mutagenity of waste

waters from Baikalsk pulp and paper mill: evaluation of pollutant

contamination in lake Baikal. Mar Environ Res 1998;46(15):

2737.

Magnus E, Carlberg GE, Norske HH. TMP wastewater treatment

including a biological high-efficiency compact reactor. Nord

Pulp Pap Res J 2000a;15(1):2936.

Magnus E, Carlberg GE, Norske HH. TMP wastewater treatment

including a biological high-efficiency compact reactor. Nord

Pulp Pap Res J 2000b;5(1):3745.

Magnus E, Hoel H, Carlberg GE. Treatment of an NSSC effluent in

a biological high-efficiency compact reactor. Tappi J 2000c;

83(1):14956.

Makris SP, Banerjee S. Fate of resin acids in pulp mills secondary

treatment systems. Water Res 2002;36:287882.

Malmquist A, Ternstrom A, Welander T. In-mill biological treat-

ment for paper mill closure. Water Sci Technol 1999;40(1112):

4350.

Mandal TN, Bandana TN. Studies on physicochemical and

biological characteristics of pulp and paper mill effluents

and its impact on human beings. J Freshw Biol

1996;8(4):1916.

Mendonca R, Guerra A, Ferraz A. Delignification of Pinus teada

wood chips treated with ceriporiopsis sbvermispora for prepar-

ing high-yield kraft pulp. J Chem Technol Biotechnol 2002;

77:4118.

Merrill DT, Maltby CV, Kahmark K, Gerhardt M, Melecer H. Eval-

uating treatment process to reduce metals concentrations in pulp

and paper mill wastewaters to extremely low values. Tappi J

2001;84(4):52.

Milet GM, Duff SJB. Treatment of kraft condensates in a feedback -

controlled sequencing batch reactor. Water Sci Technol 1998;

38(45):26371.

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 375856Mobius CH, Cordes-Tolle M. Advanced treatment of paper mill

wastewaters. Water Sci Technol 1994;29(56):27382.

Mohamed M, Matayun M, Lim TS. Chlorinated organics in tropical

hardwood kraft pulp and paper mill effluents and their elimina-

tion in an activated sludge treatment system. Pertanika 1989;

2(3):38794.

Murthy BSA, Sihorwala TA, Tilwankar HV, Killedar DJ. Remov-

al of colour from pulp and paper mill effluents by sorption

techn iquea case s tudy. Ind ian J Env i ron Pro t

1991;11(5):360.

Nakamura Y, Sawada T, Kobayshi F, Godliving M. Microbial treat-

ment of kraft pulp wastewater pretreated with ozone. Water Sci

Technol 1997;35(23):27782.

Narbaitz RM, Droste RL, Fernandes L, Kennedy KJ, Ball D.

PACTk process for treatment of kraft mill effluent. Water SciTechnol 1997;35(23):28390.

Nemerow NL, Dasgupta A. Industrial and hazardous waste man-

agement. New York: Van Nostrand Reinhold; 1991.

Norris P, Marshall R, Richard M. High temperature on activated

sludge treatment performance and sludge quality in a recycle

mill. Tappi International Environmental Conference and Ex-

hibit, Denver, CO, vol. 1. Norcross, GA, 30092, USA: Tech-

nical Association for Pulp and Paper Industry (TAPPI); 2000.

p. 3837.

Oconnor B, Kovacs T, Gibbons S, Strang AL. Carbon dioxide in

pulp and paper mill effluents from oxygen -activated sludge

treatment plants as a potential source of distress and toxicity

to fish. Water Qual Res J Can 2000;35(2):189200.

Oeller HJ, Daniel I, Weinberger G. Reduction in residual COD in

biologically treated paper mill effluents by means of combined

Ozone and Ozone/UV reactor stages. Water Sci Technol 1997;

35(23):26976.

Owens JW, Swanson SM, Birkholz DA. Environmental monitoring

of bleached kraft pulp mill chlorophenolic compounds in a

Northern Canadian River system. Chemosphere 1994;29(1):

89109.

Peerbhoi Z. Treatability studies of black liquor by UASBR-PhD

thesis 2000. University of Roorkee, India.

Perez M, Romero LI, Sales D. Comparative performance of high

rate anaerobic thermophilic technologies treating industrial

wastewater. Water Res 1998;2(3):55964.

Perez M, Torrades F, Domenech X, Peral J. Removal of organic

contaminants in pulp effluents by AOPs: an economic study.

J Chem Technol Biotechnol 2002a;77:52532.

Perez M, Torrades F, Garcia-Hortal JA, Domenech X, Peral J. Re-

moval of organic contaminants in paper pulp treatment effluents

under fenton and photo-fenton conditions. Appl Catal 2002b;

36(1):6374.

Perez M, Torrades F, Domenech X, Peral J. Treatment of bleach-

ing Kraft mill effluents and polychlorinated phenolic com-

pounds with ozonation. J Chem Technol Biotechnol 2002c;77:

8917.

Poggi-Varaldo HM, Estrada-Vazquez C, Fernandez-Villagomez G,

Esparza-Garcia F. Pretreatment of black liquor spills effluent.

Proceedings of the Industrial Waste Conference, West Lafayette,

USA 1996;51:65161.

Prasad GK, Gupta RK. Decolourization of pulp and paper milleffluent by two White-rot fungi. Indian J Environ Health 1997;

39(2):8996.

Raghuveer S, Sastry CA. Effect of simple in-plant control measures

on the characteristics of wastewater from a pulp and paper mill.

Indian J Environ Prot 1990;10(10):73946.

Raghuveer S, Sastry CA. Biological treatment of pulp mill waste-

water and study of biokinetic constants. Indian J Environ Prot

1991;11(8):61421.

Rajeshwari KV, Balakrishnan M, Kansal A, Lata K, Kishore VVN.

State of the art of anaerobic digestion technology for industrial

wastewater treatment. Renew Sustain Energy Rev 2000;4(2):

13556.

Rajvaidya N, Markandey DK. Advances in environmental science

and technology: treatment of pulp and paper industrial effluent.

Ansari Road, New Delhi, India: A.P.H. Publishing; 1998.

Reid TK, Simon A. Feasibility study of sequencing batch reactor

technology treating high strength foul condensate for methanol

reduction. Tappi International Environmental Conference and

Exhibit, Denver, CO 2000;1:18591.

Reilama I, Ilomaki N. Respect for the environment is part of com-

petitiveness-best available technology applied to an old pulp

mill at Kastinen. Water Sci Technol 1999;40(1112):2016.

Rintala JA, Puhakka JA. Anaerobic treatment in pulp and paper mill

waste management: a review. Bioresour Technol 1994;47:118.

Rohella RS, Choudhury S, Manthan M, Murthy JS. Removal of

colour and turbidity in pulp and paper mill effluents using poly-

electrolytes. Indian J Environ Health 2001;43(4):15963.

Rovel JM, Trudel JP, Lavalle P, Schroeter I. Paper mill efflu-

ent treatment using biofliltration. Water Sci Technol 1994;

29(1011):21722.

Roy-Arcand L, Archibald FS. Ozonation as a treatment for mechan-

ical and chemical pulp mill effluents. Ozone: Sci Eng

1996;18:36384.

Rudolfs W, Amberg HR. White water treatment: V. Areation with

nonflocclent growths. Sew Ind Wastes 1953;25(1):708.

Rusten B, Mattsson E, Due BA, Westren T. Treatment of pulp and

paper industry wastewaters in novel moving bed biofilm reac-

tors. Water Sci Technol 1994;30(3):16171.

Sakurai A, Yamomoto T, Makabe A, Kinoshita S, Sakakibara M.

Removal of lignin in a liquid system by an isolated fungus. J

Chem Technol Biotechnol 2001;77:914.

Sandquist KK, Sandstrom E. A novel technology to treat foul con-

densate and NCG gases in a closed loop. TAPPI International

Environmental Conference and Exhibit, Denver, CO, vol. 1.

Norcross, GA, 30092, USA: Technical Association for Pulp

and Paper Industry (TAPPI); 2000. p. 14755.

Saunamaki R. Activated sludge plants in Finland. Water Sci Tech-

nol 1997;35(23):23543.

Saxena N, Gupta RK. Decolourization and delignification of pulp

and paper mill effluent by white rot fungi. Indian J Exp Biol

1998;36:104951.

Schmidt T, Lange S. Treatment of paper mill effluent by the

use of ozone and biological systems: large scale application

at lang paper, Ettringen (Germany). Tappi International Envi-

ronmental Conference and Exhibit, Denver, CO, vol. 2. Nor-

cross, GA, 30092, USA: Technical Association for Pulp and

Paper Industry (TAPPI); 2000. p. 76575.

D. Pokhrel, T. Viraraghavan / Science of the Total Environment 333 (2004) 3758 57Schnell A, Hall ER, Skog S. Anaerobic and aerobic treatability of

high-yield sulphate spent liquor. Water Pollut Res J Can

1992;27(3):60120.

Schnell A, Sabourin MJ, Skog S, Garvie M. Chemical character-

ization and biotreability of effluents from an integrated alkaline-

peroxide mechanical pulping/machine finish coated paper mill.

Water Sci Technol 1997;35(23):714.

Schnell A, Steel P, Melcer H, Hodson PV, Carey JH. Enhanced

biological treatment of bleached kraft mill effluents: I. Removal

of chlorinated organic compounds and toxicity. Water Res

2000a;34(2):493500.

Schnell A, Steel P, Melcer H, Hodson PV, Carey JH. Enhanced

biological treatment of bleached kraft mill effluents: II. Reduc-

tion of mixed function oxygenase (MFO) induc