Journal of Environmental Science and Health, Part A (2011) 46, 833–843Copyright C© 2011 FPInnovationsISSN: 1093-4529 (Print); 1532-4117 (Online)DOI: 10.1080/10934529.2011.579850

Effluent monitoring at a bleached kraft mill: Directions forbest management practices for eliminating effects on fishreproduction

PIERRE H. MARTEL1, TIBOR G. KOVACS1, BRIAN I. O’CONNOR1, SHARON SEMENIUK2, L. MARKHEWITT3, DEBORAH L. MACLATCHY4, MARK E. MCMASTER3, JOANNE L. PARROTT3, MICHAEL R.VAN DEN HEUVEL5 and GLEN J. VAN DER KRAAK6

1FPInnovations, Pointe-Claire, QC, Canada2Domtar Inc, Espanola, ON, Canada3Aquatic Ecosystem Protection Research Division, Environment Canada, Burlington, ON, Canada4Canadian Rivers Institute, Department of Biology, Wilfrid Laurier University, Waterloo, ON, Canada5Canadian Rivers Institute, Department of Biology, University of Prince Edward Island, Charlottetown, PEI, Canda6Department of Integrative Biology, University of Guelph, Guelph, ON, Canada

A long-term monitoring study was conducted on effluents from a bleached kraft pulp and paper mill located in Eastern Canada. Thestudy was designed to gain insights into temporal effluent variability with respect to fish reproduction as it related to production upsets,mill restarts and conditions affecting biological treatment performance. Final effluent quality was monitored between February 2007and May 2009 using biochemical and chemical oxygen demand, total suspended solids, resin and fatty acids, a gas chromatographicprofiling index, and the presence of methyl substituted 2-cyclopentenones. Selected effluent samples were evaluated for effects on fishreproduction (egg production) using a shortened version of the adult fathead minnow reproductive test. The events relating to negativeeffects on fish reproduction were upsets of the pulping liquor recovery system resulting in black liquor losses, operational upsets ofthe hardwood line resulting in the loss of oxygen delignification filtrates, and conditions that reduced the performance of biologicaltreatment (e.g., mill shutdown and low ambient temperatures). The reductions in egg production observed in fathead minnow wereassociated with biochemical oxygen demand values > 20 mg/L, GC profiling indices > 1.2 and the presence of methyl-substituted2-cyclopentenones at concentrations > 100 µg/L. This study demonstrated the importance of both in-plant measures for controllingthe loss of organics as well as the optimum operation of biological effluent treatment for eliminating effluent-related effects on fishreproduction (egg production) in the laboratory.

Keywords: Kraft, effluent, fish, reproduction, biochemical oxygen demand.

Introduction

In Canada, the discharge of pulp and paper mill effluents isregulated under the Fisheries Act.[1] The regulations requireEnvironmental Effects Monitoring (EEM) studies in the re-ceiving waters to evaluate the effectiveness of the existingregulatory limits. A key component of the EEM programis a comparison of wild fish populations at sites above andbelow effluent emissions. After three cycles of EEM stud-ies, a national pattern emerged for fishes living in waterscontaining mill effluents. The fish populations were foundto have increased condition factors and larger livers, but

Address correspondence to Pierre Martel, FPInnovations,570 boul. St.-Jean, Pointe-Claire, QC; E-mail: pierre.martel@fpinnovations.caReceived November 1, 2010.

smaller gonads.[2] This was interpreted as an indication ofmetabolic disruption with the potential to diminish overallreproductive capacity. Alterations in reproductive functionassociated with mill effluents have also been reported fromstudies around the world for over 25 years.[3] As such, theelimination of effluent-related effects on fish reproductionbecame an important environmental objective for industryand government.

When effluent-related effects in the receiving environ-ment have been confirmed, the EEM program requires theinitiation of Investigation of Cause (IOC) and Investigationof Solution (IOS) studies for remedial purposes. There areno proven tests that can practically replicate the metabolicdisruption pattern, especially the gonad size effect in thelaboratory, and no readily available protocols for IOC/IOSwork.[3] To address this shortcoming, a national researchprogram, involving government, academia and industry,

834 Martel et al.

was initiated in Canada with the goals of identifying or de-veloping appropriate diagnostic tools.[4] These tools wouldthen be used to identify the causative agent(s) and eventu-ally to identify best management practices for eliminatingsuch effects.

An evaluation of diagnostic tests for IOC/IOS work wasinitiated in Canada with effluent from a bleached kraftmill.[4,5] One of the tests under evaluation was a shortenedversion of the adult fathead minnow (Pimephales promelas)reproduction test previously developed by the USEPA[6] forassessing the endocrine disrupting potential of chemicals.Essentially, the modified test involves a 5-day exposure ofthe fish to effluents with egg production as the main end-point.[7] This test showed that the egg production endpointin fathead minnow exposed to the kraft mill effluent wassimilar to the egg production endpoint in a life-cycle testwith the same species exposed to the same effluent [4,5] andthe condition of the fathead minnow in the life-cycle testwas similar to the condition of wild fishes captured down-stream from the mill in terms of weight, length and gonadsize. As such, the fathead minnow egg production test ap-peared to have some potential for IOC/IOS work.

The evaluation of diagnostic tests required sampling ofeffluent at the kraft mill on different occasions. This ledto the finding that effluent quality at the mill in termsof organic loading, as determined by the summation ofpeak areas in the gas chromatographic (GC) profile of thesolvent-extracted effluent, was variable[4] and potentiallylinked to effects on fathead minnow egg production. Un-der typical operating conditions, the effluent had no effecton fish reproduction. A reduction of egg production wasonly noted when the effluent organic loading increased fol-lowing a mill startup, which resulted in atypical operat-ing conditions. A survey of effluents from nine kraft andmechanical pulp mills (the main types of manufacturingprocesses in Canada) also found that effluent organic con-tent, based on GC analysis as well as biochemical oxygendemand (BOD), correlated with effects on fish reproduc-tion.[8] Effluents with the lowest BOD and GC peak areashad no effects on the fish while effluents with the highestGC peak areas and BOD caused a complete inhibition ofegg production. The type of manufacturing process had nobearing on whether a mill effluent caused an effect or not.

Although the focus of the first phase of the nationalIOC/IOS project was on diagnostic tools, the work to datealso identified important leads for investigative strategiesand effluent management. Variations in effluent quality willcomplicate IOC work aimed at identifying the agent(s) thatcan cause changes in fish reproduction. However, under-standing the reasons for these variations could minimize theneed for IOC work and be helpful in developing effectiveremedial strategies. In terms of investigative strategies, ithas been shown that monitoring effluent quality at selectedmills or comparing the effluent quality from different millsusing similar manufacturing processes could provide im-portant clues for best management practices. Such a line of

investigation could be particularly helpful as the previousstudies demonstrated that some mills are already operatingin ways that the effluent discharges have little or no impacton fish reproduction.[4,5,8] These mills provide an opportu-nity for identifying the specific operating conditions thatwill ensure minimal effluent-related impacts.

Based on these promising leads, a study involving anin-depth monitoring of effluent variability at a secondbleached kraft mill was initiated. The main objectives were(i) to further evaluate the relationship between effluent or-ganic content and fish egg production and (ii) to identifymill operating conditions that influence effluent quality interms of effects on fish reproduction, which could eventu-ally lead to the development of best management practicesat kraft mills.

Materials and methods

Mill selected for monitoring

The mill selected for study was a bleached kraft facilityproducing about 1000 t/d of pulp and 225 t/d of spe-cialty papers. This mill pulps softwoods and hardwoods,which are respectively bleached according to the follow-ing sequences: ODEoDnD and OA(zd)EDnD where O:oxygen delignification; D: chlorine dioxide; Eo: alkalineextraction reinforced with oxygen; Dn: chlorine dioxide inneutral conditions; A(zd): acid wash with ozone and chlo-rine dioxide. The softwood furnish is composed of 50%jack pine and 50% spruce. The hardwood furnish can varybetween 100% maple, aspen or birch to a mixture of 75%maple and 25% birch. The effluent is treated in a settlingbasin before passage through an aerated lagoon with a 7-day hydraulic retention time before discharge to a river.

Experimental design

This long-term monitoring study is based on 21 biotreatedsamples and one untreated effluent sample collected at themill between February 2007 and May 2009. The effluentsamples were taken by mill staff during normal milloperating conditions, during periods of upsets and duringperiods of atypical operating conditions associated withshutdowns and startups. Of these, 9 effluents were testedfor their effects on egg production, 6 in short-term tests(5-d exposure to effluent) and 3 in 1 medium-term test(21-d exposure to effluent) with the fathead minnow. Therelationship between egg production and effluent qualityas described by chemical parameters was assessed byestablishing a time line which includes normal operatingconditions and 3 major events at the mill.

The first event was an evaporator upset the night ofFebruary 6, 2007 which resulted in a loss of black liquorto the aerated lagoon. The second event occurred inlate September 2008 where operational problems on thehardwood line resulted in excess oxygen delignificationstage filtrate being sent to the wastewater treatment system.

Effluent monitoring at a bleached kraft mill 835

The third event was an effluent treatment upset following ascheduled shutdown in late December 2008. Effluent sam-ples were tested for their effects on egg production on twooccasions in 2009 following a mill shutdown and startup,including an evaluation of the performance of biologicaltreatment by comparing the effects of effluents sampled atthe inlet and outlet of the aerated lagoon.

Effluent chemical analyses

All samples were subjected to solvent extraction, followedby gas chromatography/mass spectrometry (GC/MS)analyses. A volume of 250 mL of effluent was added toa separatory funnel with 25 µL of an internal standard so-lution (C21 standard) containing 1 mg/mL each of methylheneicosanoate and tricosanoic acid (Sigma-Aldrich, St.Louis, MO). Samples were extracted with 2 × 100 mLvolumes of HPLC grade methyl tert-butyl ether (MTBE,Fisher Scientific, Nepean, ON). The MTBE extract wastransferred to a 250 mL round-bottom flask and reducedto approximately 1.5 mL with a vacuum rotary evapora-tor then brought to a final volume of 200 µL in a vialunder a gentle stream of nitrogen. The extract was thenmethylated with diazomethane and 2 µl injected into theGC/MS. GC/MS analyses were performed with an Ag-ilent 6890 Series GC coupled with a 5973 mass selectivedetector. The MTBE extract was injected for analysis insplitless mode at 250◦C. Analytes were separated on a 30m × 0.25 µm i.d. Rxi-1MS capillary column, 0.25 µm filmthickness (Restek, Bellefonte, PA) with helium carrier at 1.3mL/min. The GC oven program was 60◦C for 10 min thenincreased at 5◦C/min to 290◦C and held for 20 min.

Differences in the amounts of organics present in variouseffluents were examined in a quantitative manner by com-paring the total peak area for each chromatogram. Sinceeach effluent extracted contained a C21 standard it waseasy to compare the relative areas of each and differenti-ate between effluents. The GC/MS profiles were obtainedusing positive ion electron impact ionization. The massspectrometer was programmed to scan m/z 40–610 amu ata scan rate of 2.6 scans/sec. Peaks in the resulting totalion chromatograms were integrated to calculate the rela-

tive amounts of extractives present, based on the area ofthe C21 standard.

Here after, this comparison will be referred to as a GCprofile index. For the purpose of establishing a compari-son point, the effluent sample collected on November 10,2008, that did not affect egg production, was assigned aGC profile index of 1.0. The chromatograms for the 21effluent samples analyzed were examined for the presenceof a family of methyl substituted 2-cyclopentenones. Theconfirmation for these isomers was accomplished by com-parison with mass spectra from standards that had beensynthesized by Voss.[9] The samples were also analyzed forresin/fatty acids (RFAs) as per the method described byVoss and Rapsomatiotis.[10] The effluent samples were alsoanalyzed for biochemical oxygen demand (BOD) and otherconventional effluent parameters such as chemical oxygendemand (COD) and total suspended solids (TSS) accordingto standard methods.[11]

Adult fathead minnow reproduction tests

The adult fathead minnow test method was adapted fromAnkley et al.[6] and has been used for previous work withmill effluents.[7] The sexually mature fathead minnows wereraised in laboratory well water (temperature 25 ± 1◦C, pH∼8.2, hardness ∼250 mg/L as CaCO3, alkalinity ∼160mg/L as CaCO3) until displaying first signs of sexualmaturity and separated by sex until they reached between 8and 14 months of age. The pre-exposure phase of the testswas initiated by distributing adult fish in groups of 2 malesand 4 females in each aquarium containing two spawningsubstrates. From these, groups of fish that demonstratedgood reproductive performance (≥18 eggs/female/day)were selected and these groups were randomly assignedto one of the four replicates for each of the treatments.Detailed test conditions are described in Table 1.

Five short-term tests (5-d effluent exposure) were con-ducted with one effluent sample each and one medium-termtest (21-d effluent exposure) was conducted using a differenteffluent sample each week. Effluents were delivered to fourreplicate tanks and temperature, dissolved oxygen and pHwere monitored daily. During the effluent-exposure phase,

Table 1. Summary of test conditions for short-term tests with fathead minnow.

Pre-exposure phase 7 to 14 dEffluent exposure 5 to 7 dTank turnovers 4/dQuantity of effluent used 200 L/dReplicates 4 (2 males and 4 females in 12.5 L)Loading density 0.33 to 0.40 g/LPhotoperiod 16 h light and 8 h darkFeeding Ad libitum; freshly hatched Artemia (brine shrimp) three-times a dayEndpoints measured Egg production, number of spawns, egg fertilization, gonad weight, body length and weightpH 7.4 to 8.5Dissolved oxygen > 60% saturationTemperature 24 ◦C ± 1◦C

836 Martel et al.

Table 2. Morphometric indicators of the fish at the end of the tests. Results are presented as means with standard error. There wereno statistical differences for these parameters when compared to controls.

Control 100% Effluent

Effluent Sampling Dates Parameter Males Females Males Females

Feb. 19, 2007 CF 1.6 (0.1) 1.3 (0.0) 1.5 (0.1) 1.3 (0.0)GSI,% 1.2 (0.1) 12 (0.7) 1.4 (0.2) 14 (0.8)BW, g 5.4 (0.3) 2.2 (0.1) 5.0 (0.2) 2.4 (0.2)BL, mm 70 (1.7) 55 (0.9) 69 (1.3) 57 (1.2)

Nov. 3, 10 & 17, 2008 CF 1.6 (0.04) 1.5 (0.04) 1.5 (0.02) 1.5 (0.07)GSI,% 1.1 (0.2) 13.9 (0.9) 1.0 (0.2) 13.5 (1.2)BW, g 5.4 (0.2) 2.6 (0.1) 5.4 (0.2) 2.5 (0.1)BL, mm 71 (1.2) 56 (0.6) 72 (0.9) 56 (0.8)

Jan. 13, 2009 CF 1.4 (0.02) 1.3 (0.03) 1.4 (0.04) 1.3 (0.02)GSI,% 0.9 (0.2) 13.4 (0.7) 1.3 (0.2) 13.6 (1.1)BW, g 4.7 (0.3) 2.3 (0.1) 4.2 (0.2) 2.3 (0.1)BL, mm 70 (1.4) 56 (0.6) 67 (1.1) 56 (0.7)

Feb. 16, 2009 CF 1.6 (0.03) 1.3 (0.03) 1.5 (0.04) 1.3 (0.0)GSI,% 1.2 (0.1) 11.3 (1.3) 1.4 (0.1) 13.8 (1.8)BW, g 3.8 (0.3) 1.8 (0.1) 3.2 (0.1) 1.8 (0.1)BL, mm 63 (1.4) 52 (0.6) 60 (0.8) 53 (0.4)

Mar. 18, 2009 CF 1.5 (0.04) 1.3 (0.03) 1.5 (0.04) 1.3 (0.03)GSI,% 1.5 (0.1) 13 (1.0) 2.1 (0.2) 13 (1.1)BW, g 4.1 (0.1) 1.9 (0.1) 4.2 (0.2) 1.9 (0.1)BL, mm 65 (1.1) 53 (0.6) 65 (1.3) 52 (0.7)

May 29, 2009 CF 1.4 (0.04) 1.3 (0.03) 1.4 (0.06) 1.3 (0.03)GSI,% 1.3 (0.1) 13 (1.0) 1.7 (0.1) 14 (1.2)BW, g 4.0 (0.2) 2.5 (0.1) 3.7 (0.1) 2.2 (0.1)BL, mm 66 (1.0) 58 (0.6) 65 (1.1) 56 (0.7)

CF: Condition factor; GSI: Gonad somatic index, BW: Body weight, BL: Body length.

eggs were collected daily and counted. Egg production atthe end of the test was calculated as the number of eggsper female per day in each replicate. At the end of the test,the fish were sacrificed and measured for body weight andlength. Gonads were excised and weighed.

For each test, egg production and morphometric param-eters (e.g., weight and length) of the effluent-exposed fishwas compared to the control fish by t-test[12] if the data metassumptions of normality and homogeneity (either with orwithout log transformation) or the Mann-Whitney test ifthe data failed assumptions of normality/homogeneity. Allanalyses were performed at the 95% confidence level.

Results

The morphometric fish measurements at the end of eachtest are summarized in Table 2. None of the measurementswere affected by effluent exposure. The results of egg pro-duction and chemical analysis of effluents during the 3 millevents are shown in Table 3.

Mill Event 1: Evaporator upset of February 6, 2007

The first fathead minnow reproduction test was completedin February 2007 shortly after an evaporator upset. This

effluent was found to significantly reduce egg productionby 91% (see Table 3). The concentrations of BOD, COD andRFAs were 28, 404 mg/L and 100 µg/L, respectively. Thetotal methyl substituted 2-cyclopentenone concentrationwas 103.2 µg/L and the GC profile index was estimated tobe 1.75.

Mill Event 2: Hardwood line operational upset fromSeptember 29 to October 9, 2008

The process upset in the hardwood pulping line occurredfrom September 29 to October 9. This event was precededby a period of normal operation where the chemical mon-itoring of effluents can be interpreted to represent normaloperating conditions. Five samples were analyzed for theirGC profile index and these varied between 1.01 and 1.62showing appreciable variation in organic content (Table 3).For these 5 samples, the BOD varied from 15 to 26 mg/L,the COD from 248 to 286 mg/L and the TSS from 17 to 30mg/L. There were non-detectable amounts of methyl sub-stituted 2-cyclopentenones in these samples and the RFAconcentration was ≤ 40 µg/L (Table 3).

During the process imbalance on the hardwood line foureffluent samples were analyzed (see Table 3). These sam-ples were taken between September 29 and October 9 andshowed GC Profile Indices varying between 1.47 and 2.53

Tab

le3.

Res

ults

offa

thea

dm

inno

weg

gpr

oduc

tion

test

san

dch

emic

alan

alys

isfo

rse

lect

edse

cond

ary

trea

ted

efflu

ent

sam

ples

take

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the

stud

ype

riod

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7to

2009

.

Mea

neg

gpr

oduc

tion

eggs

/fem

ale/

day

(SE

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uent

sam

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te10

0%ef

fluen

tC

ontr

olG

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inde

xB

OD

mg/

LC

OD

mg/

LT

SS

mg/

LR

FAµ

g/L

Met

hyl-

subs

titu

ted

2-cy

clop

ente

none

s,µ

g/L

Mill

Eve

nt1:

Eva

pora

tor

upse

tF

ebru

ary

6,20

07F

eb.1

9,20

077∗

(3)

81(7

)1.

7528

404

2310

010

3.2

Nor

mal

oper

atin

gco

ndit

ions

Aug

.14,

2008

1.42

261

2771

271

40nd

Aug

.18,

2008

1.01

191

2861

271

40nd

Aug

.21,

2008

1.35

151

2481

171

40nd

Aug

.25,

2008

1.62

151

2521

301

30nd

Aug

.28,

2008

1.35

201

2661

201

30nd

Mill

Eve

nt2:

Har

dwoo

dlin

ere

cove

ryup

set

from

Sept

embe

r29

toO

ctob

er9,

2008

.Se

p.29

,200

82.

0426

126

8130

117

0nd

Oct

.2,2

008

1.95

431

3221

431

107

1.7

Oct

.7,2

008

2.53

311

3021

301

60nd

Oct

.9,2

008

1.47

321

3161

301

30nd

Nor

mal

oper

atin

gco

ndit

ions

Oct

.13,

2008

0.74

161

3171

271

10nd

Oct

.16,

2008

1.16

221

3231

231

60nd

Oct

.20,

2008

1.17

311

3441

201

70nd

Nov

.3,2

008

30(7

)33

(4)

0.65

1440

310

20nd

Nov

.10,

2008

28(7

)40

(5)

1.00

1941

55

3010

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7,20

0849

(6)

34(4

)0.

9017

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Dec

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94∗

(4)

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4653

426

1960

111.

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91.

4332

120

112

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(4)

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8415

345

1250

8.2

Mar

.18,

2009

18(6

)33

(11)

1.15

1830

727

88M

ay29

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915

(2)

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7516

301

1440

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1 data

supp

lied

byth

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ill;∗ St

atis

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<0.

05);

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EM

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ean.

837

838 Martel et al.

Fig. 1. Cumulative egg production by fathead minnows exposed tofinal effluents during conditions of normal operation November10th 2008. BOD of 100% effluent is 19 mg/L.

indicating greater organic losses than prior to beginningof the process imbalance. The BOD (26 to 43 mg/L) andRFA (30 to 107 µg/L) concentrations were also found to begreater but the methyl substituted 2-cyclopentenones werefound only at trace level in one sample (October 2).

For 3 other samples taken from October 13 to 20, theGC Profile Indices returned to levels before the processimbalance and stabilized between 0.74 and 1.17. For thesesamples, the BOD levels ranged from 16 to 31 mg/L, RFAswere ≤ 70 µg/L and methyl- substituted 2-cyclopentenoneswere all below detection levels (0.1 µg/L). The return ofthe effluent quality in terms of chemical indicators to con-ditions similar to normal operations provided the triggerfor a fish reproduction test with effluent that could be con-sidered to reflect normal mill operating conditions. Thus,a 21 day test was undertaken with three effluents sam-pled in successive weeks starting on November 3 (see Ta-ble 3). For this experiment, the egg production data forcontrols and 100% effluent-exposed fish are shown on aweekly basis corresponding to each of the three effluentsamples that were taken. There was no statistically signif-icant reduction in egg production during the three weeksof the experiment. The results of egg production duringexposure to a range of different effluent concentrations forthe sample taken on November 10th are shown in Figure1. Again there are no significant differences in egg pro-duction in all of the effluent concentrations compared tocontrols. The same was true of the overall egg productionover the 21 days of the exposure with mean (standard er-ror) egg production for controls and 100% effluent exposedfish of 36 (4) and 36 (6), respectively. Only trace amountsof methyl-substituted 2-cyclopentenones were detected inthe samples of November 10 and 17 and concentrationsof TSS and RFA were the lowest during the monitoringperiod. The BOD was ≤ 19 mg/L, but the COD was thehighest during the monitoring period (around 400 mg/L)(Table 3).

Fig. 2. Cumulative egg production by fathead minnows exposedto final treated effluent sampled during biotreatment upset con-ditions on January 13th 2009. BOD of the 100% effluent is 53mg/L.

∗Statistically different from the control p < 0.05.

Mill Event 3: Mill shutdown between December 13 and 28,2008, followed by effluent biotreatment upset

A scheduled shutdown occurred between December 13 and28. In this case, a decision was made to monitor the effluentquality after the shutdown for some time not only in termsof chemical indicators but also in terms of potential toaffect fish egg production.

Subsequent to the start-up, there was an accidental upsetin the aerated lagoon that prevented normal performancein terms of BOD removal. The effluent BOD concentra-tion on January 13 was 53 mg/L and this effluent causedan 88% reduction in the mean number of eggs produced perfemale per day. The threshold for effects on egg productionwas between 30% v/v and 65% v/v effluent concentrationas shown in Figure 2. The concentration of methyl- substi-tuted 2-cyclopentenones was found to be the highest in atreated effluent in this study, totalling 111.6 µg/L. This wasaccompanied by a GC Profile Index of 1.46, of the same or-der as those recorded during the September 2008 hardwoodline recovery upset, and 426 mg/L COD. The concentra-tions of RFA and TSS were not significantly different fromthose measured during the stabilized mill operation in Oc-tober. A month after start-up (February 3), the presenceof methyl-substituted 2-cyclopentenones was still evidentwith a total of 79.2 µg/L. The GC Profiling Index andBOD were still elevated at 1.43 and 32 mg/L, respectively(Table 3).

A series of tests were completed between February 16,2009 and May 29, 2009. These involved the assessment ofthe effluent biotreatment (aerated lagoon) system on Febru-ary 16, 2009 and included a direct comparison of the efflu-ents before and after biotreatment. As shown in Figure 3the threshold for effects of the effluent before biotreatmentwas between 30% v/v and 65% v/v effluent concentrationwhile there were no statistically significant reductions in

Effluent monitoring at a bleached kraft mill 839

Fig. 3. Cumulative egg production by fathead minnows exposed to effluents sampled February 16th 2009 before and after biotreatment.∗Statistically different from the control at p < 0.05.

egg production caused by the biotreated effluent. The ef-fluent before biotreatment contained 205 mg/L of BOD,the GC Profile index was 3.78 and the concentration ofmethyl-substituted 2-cyclopentenones was 281 µg/L. Thebiotreated effluent contained 15 mg/L BOD and 8 µg/Lmethyl substituted 2-cyclopentenones and the GC Profileindex was 0.84 (Table 3).

The last 2 fish reproduction tests were conducted March18 and May 29, 2009. The two samples had GC ProfilingIndices of 1.15 and 0.75 respectively while BOD concentra-tions were ≤ 18 mg/L. These samples also did not causestatistically significant reductions in egg production (Table3) even though the sample of March 18 caused a reduc-tion of 45% in egg production. The egg production by the100% effluent-exposed fish is within the criteria for controlas indicated by the control production during the test ofthe effluent sampled on May 29, 2009. Nevertheless, the45% reduction of egg production by the fish exposed tothe March 18 sample may be symptomatic of a decrease ineffluent quality. The concentration of methyl-substituted 2-cyclopentenones in the sample of March 18 was 98 µg/L.

Discussion

During the 1990s, many mills in North America upgradedoperating conditions that resulted in improvements to ef-fluent quality. These upgrades included installation or im-provement of effluent biological treatment systems, changesin pulp bleaching (mostly from elemental chlorine to chlo-rine dioxide) and various other alterations.[3] Nevertheless,assessment of mill effluents indicated that various indica-tors of fish reproduction continued to be affected.[3] A re-newed effort was required to find the means of eliminatingthe residual effects on fish reproduction associated with

mill effluents. The initial results of this renewed effort haveshown that the effluent from the same mill can be variable,ranging from no effects on egg production to a substantialdecrease in egg production.[4] A second study has shownthat the quality of effluents from different pulp and pa-per mills using the same manufacturing process can alsobe quite variable and that the effluents from some millshave no effects on egg production in laboratory tests.[8] Inboth previous studies, the effects on egg production werelinked to the organic content of the effluent. This monitor-ing study confirmed the findings of the previous work andprovided new insights as to the causes of the effluent vari-ability, which could be used to implement BMPs at kraftmills.

Effluent organic content and effects on fish reproduction

The effluents in this study were analyzed for groupparameters giving an indication of overall organic losses aswell as individual compounds such as methyl-substituted2-cyclopentenones and RFAs. The group parametersincluded BOD and the GC profile index. The BOD is infact a measure of the total biologically degradable organicmatter in effluent that is determined in terms of oxygenutilization over a 5-day period. It is often used to assessbiological treatment performance[13] and it is also one ofthe regulated effluent parameters in Canada, the othersbeing total suspended solids and acute lethality.[1] TheGC profile index is simply the summation of the total ionchromatogram peak areas obtained from a GC/MS fullscan of a solvent-extracted effluent sample. Its advantage isthat the analysis can be done in a few hours rather than the5 days required for the BOD measurement. The individualcompounds monitored in this study represent specificcomponents of the wood furnish that are suspected to be

840 Martel et al.

Fig. 4. The relationship between BOD of the final treated effluentsand egg production (expressed as the percent of the control).

the source of substances affecting fish reproduction.[3] Themethyl-substituted 2-cyclopentenones are degradationproducts of cellulose resulting from the kraft cooking ofwood chips[9] and the RFAs are extractives in softwoodsthat are often associated with acute lethal toxicity to fish.[14]

For the eight final effluents that were tested for effects onegg production and BOD, the relationship between BODand egg production (expressed as the percent of the control)is shown in Figure 4. A significant correlation is apparentsuch that greater BOD concentrations resulted in greaterreductions of egg production with the effluent effects beingstatistically significant when the BOD exceeded 20 mg/L.

Fig. 5. Relationship between GC profile index and egg production(expressed as the ratio of the egg production of the exposed fishover that of the controls).

The situation is similar for the relationship between the ef-fluent GC profile index and egg production shown in Figure5. An illustration of the quality of the effluents on the basisof the GC profile index can also be seen in Figure 6. Thechromatograms illustrate the GC/MS trace for the two ef-fluents that significantly affected egg production (February19, 2007 and January 13, 2009) and the reference November10, 2008 sample that did not affect egg production. From avisual inspection of the chromatograms, the lower numberof individual peaks and lower intensity of individual peaksfor the effluent that did not affect egg production is evident.

Fig. 6. Illustration of GC/MS total ion chromatograms for the two samples found to cause a significant reduction in egg productionin fathead minnows and the sample chosen as a reference for the Gas Chromatogram profile index (IS represents internal standards).(color figure available online)

Effluent monitoring at a bleached kraft mill 841

Fig. 7. Relationship between total effluent methyl substituted 2-cyclopentenones and egg production (expressed as the percent ofthe control).

Concerning the individual compounds, the correlationbetween the effluent concentrations of methyl substituted2-cyclopentenones and effects on egg production shownin Figure 7 was found to be statistically significant. Twoeffluent samples had concentrations of methyl-substituted2-cyclopentenones exceeding 100 µg/L and these effluentssignificantly affected egg production. Despite the correla-tion between effluent concentrations of methyl-substituted2-cyclopentenones and effects on egg production, there isno evidence available to suggest direct causality. On theother hand, the correlation between effluent RFAs and ef-fects on egg production (relationship not shown) was notfound to be significant (r = -0.555 and p > 0.05) and, assuch, the RFAs can likely be ruled out as potential causativeagent(s).

Mill operating conditions and effluent quality

The effluent from the bleached kraft mill of this study didnot affect egg production of the fathead minnow undernormal operating conditions. The operating conditions thatlead to negative effects of the effluents on fish reproductionwere associated with an evaporator upset, a disturbance inthe oxygen delignification process and an aerated lagoonmalfunction following a mill shut-down. All three of theseevents were characterized by changes in the chemical profileof the effluent.

The first two events lead to excessive loss of organicswithin the mill and demonstrated the importance of in-plant control. The first event involved an upset in the op-eration of the evaporators that are used to concentrateblack liquor for burning and recovery purposes. This re-sulted in uncharacteristic black liquor losses. Black liquoris the spent cooking liquor from the kraft process wherewood chips are treated with sodium sulphide and sodiumhydroxide to produce pulp consisting mainly of cellulose.The black liquor contains spent cooking chemicals and

highly concentrated wood residues and wood degradationcompounds, such as extractives, lignin, organic acids andmethanol.[15]

The second event involved operational disturbances onthe hardwood line resulting in excess oxygen delignificationstage filtrates being sent to waste. Oxygen delignificationis an extension of the cooking process in which part ofthe residual lignin left in pulp is removed before the pulpproceeds to bleaching. The filtrates from this process aresimilar to black liquor and also contain wood residues.Under normal operating conditions these filtrates are notsent to sewer. Rather, the filtrates can be added to the blackliquor and sent to the recovery furnace[16] or the filtratescan be used for pulp washing (brownstock washing).

The third event highlighted the importance of efficienteffluent biological treatment as a critical factor that willultimately influence effluent quality. This event occurredin late December 2008 following a mill shutdown. Duringsuch shutdowns, mill staff usually undertakes maintenancetasks which could result in atypical release of organics infinal effluent. As well, at the time of start-up, it may takesome time to stabilize in-plant as well as effluent biologicaltreatment conditions which again could result in increasedorganic loadings. Indeed, our previous study at anotherkraft mill showed a deterioration of effluent quality follow-ing a mill shutdown/start-up situation resulting in dimin-ished egg production by the fish.[4] During the shutdown ofDecember 2008, however, very little maintenance was car-ried out and there were no difficulties with start-up. Rather,the problem was caused by the inadvertent flushing of thebacterial biomass from the aerated lagoon and extremelycold temperatures (−30◦C) which prolonged recovery ofthe biomass. This resulted in the effluent treatment systemnot functioning at its optimum following start-up. For ex-ample, on January 13, 2009 the BOD removal efficiency wasapproximately 70% compared to ≥ 90% removal under nor-mal conditions. This resulted in observable effects on eggproduction caused by the treated effluent (see Fig. 2) whichwere similar to the effect of the effluent before treatment(see Fig. 3). The direct comparison of the effluent beforeand after the aerated lagoon during February 2009 clearlydemonstrated the importance of biological treatment interms of overall organic loading (BOD and GC profile in-dex), methyl-substituted 2-cyclopentenones and effects onegg production. These results confirmed the results of a pre-vious study which provided evidence that effluent biologicaltreatment has demonstrable benefits in reducing reproduc-tive effects and that effluent biological treatment could bean important component of best management practices.[17]

Leads for best management practices

A key goal of the industry in Canada is to alleviate effluent-related effects in the EEM program. It is important torecognize that the exact relationship between effluent ef-fects on egg production in short term tests using laboratory

842 Martel et al.

fish species and gonad size in different species of wild fish ispresently unclear. However it is recognized that effects onegg production are significant and directing Best Manage-ment Practices toward reducing effects on egg productionwould have environmental benefits.

Collectively, the monitoring study showed that controlof organic losses at a kraft mill needs to be an importantcomponent of a strategy to abate potential effluent-relatedeffects on fish reproduction. In particular, the BOD mea-surement and the GC profile index are good indicators oforganic losses due to spills, upset conditions or underper-forming effluent biological treatment systems. The increasein the presence of methyl-substituted 2-cyclopentenones aremore specific indicators of losses related to black liquor[9]

either as a direct result of a black liquor spill or as a re-sult of other operation upsets, such as upsets in evaporatorfunction as seen in this study. The methyl-substituted 2-cyclopentenones can survive effluent biological treatmentto varying degrees[18] making them potentially useful mark-ers of mill upsets that result in excessive black liquor losses.The presence of these compounds in the effluent samplesfollowing the mill shutdown of December 2008 suggeststhere were atypical losses of black liquor during this periodand the condition was exacerbated by the underperformingtreatment system due to the accidental loss of biomass andlow ambient temperatures.

Another possible source of the methyl-substituted 2-cyclopentenones could be the condensates generated duringthe recovery process at kraft mills. Condensates are handledand treated under various conditions from mill to mill.[15]

Previous studies [19,20] have shown that in-plant treatmentof condensates by reverse osmosis was beneficial for elim-inating effluent-related effects on hormone levels in fish.Systematic process stream surveys need to be completedto identify all the sources of various methyl-substituted 2-cyclopentenenone isomers and their fate during biologicaltreatment.

At kraft mills, overall organic losses can be controlledboth in-plant and during effluent treatment.[15] This studydemonstrated the importance of both in-plant measuresfor controlling the loss of organics as well as for optimizingoperation of biological effluent treatment to reduce levelsof these organics. Effluent biological treatment was foundto be effective in eliminating effluent-related effects on fishreproduction in the laboratory as long as the in-plant lossesof organics was controlled and minimized. It may be worth-while for future studies to explore the possibility of improv-ing or further optimizing the biological treatment processsuch that the final effluent quality would be more consistenteven during instances of in-plant upsets.

In summary, based on the findings of this study, specificareas of control for minimizing effects on fish reproduc-tion could include i) controlling black liquor losses (in-cluding recovery processes and condensate handling), ii)consistently optimizing biological treatment systems, andiii) careful management of shutdown and start-up condi-

tions. The chemical indicators of this study could be ap-plied by mill staff to set specific effluent targets for kraftmills to achieve minimal effluent impact on fish reproduc-tion. These should be BOD < 20 mg/L, a GC profile indexof 1.0 (set to correspond to an effluent BOD of 20 mg/L),and a methyl-substituted 2- cyclopentenone concentration< 100 µg/L.

Acknowledgments

The authors gratefully acknowledge the support of the millstaff for their willingness to participate in this project, forsupplying effluent shipments in a timely manner and forproviding information about mill operating conditions. Wealso acknowledge the financial support of Abitibi Bowa-ter, AV Nackawic, Cascades, Domtar, Papiers White Birch,Smurfit-Stone, Tembec, and Fibria mills. The technicalwork was carried out by Maria Ricci, Tatyana Yurchuk,Robert Ross, Valerie Naish and Robert Traversari. SharonGibbons completed the statistical analyses.

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