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Water Research 37 (2003) 2813–2820

Removal of acids and sterols from mill effluents by activated sludge treatment A. Kostamo, J.V.K. Kukkonen*

Laboratory of Aquatic Ecology and Ecotoxicology, Department of Biology, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland

Received 18 January 2002; accepted 6 February 2003

Abstract

The wastewater treatment plant of an bleachingkraft located in eastern Finland was sampled in order to study the fate of extractives and the toxicity to luminescence bacteria (Vibrio fischeri)in different parts of the plant. Resin acids and sterols were analyzed from water, particles and sludge samples during three different runs. Waters before biotreatment and primary sludge were found to be toxic; but in the activated sludge treatment toxicity was removed. Duringwastewater treatment, concentrations of wood extractives were reduced over 97%. In activated sludge treatment, over 94% of the resin acids and over 41% of the sterols were degraded or transformed to other compounds. Furthermore, in general, less than 5% of the resin acids and over 31% of the sterols were removed in biosludge to the sludge thickener. Most of the extractives were discharged attached to particles. Although some disturbing factors increased the load of wood extractives during samplings, these factors did not affect the operational efficiency of the secondary treatment system. r 2003 Elsevier Science Ltd. All rights reserved.

Keywords: Wood extractives; Resin acids; Sterols; Activated sludge treatment; Flash test; Kraft pulp mill

1. Introduction have also reduced the load: modified cooking, oxygen delignification, more effective washing of pulp and more After changes in the bleaching processes, research on closed water circulation [1,3,5]. pulp mill effluents has expanded from chlorinated Secondary treatment of pulp mill effluents reduces, in compounds to wood extractives such as resin acids and addition to BOD and COD, the toxicity of effluents sterols [1]. These extractives cause foamingproblems [4,6]. Many studies have found resin acids and and are impurities in the products and on the equipment unsaturated fatty acids toxic to aquatic organisms, and of pulp and mills [2]. Since the early 1990s, the use various methods have been used to test toxicity [7–9]. of ECF bleachingtechniques has become common, Recently, bacterial testinghas become popular because replacingthe use of chlorine gas [3]. Moreover, in the it is sensitive and relatively quick and easy to perform 1980s, the introduction of activated sludge wastewater [6,10,11]. treatment has reduced BOD in effluents by 85–95% and Quite recently, it has been shown that plant sterols COD by 40–80% [4]. Other improvements in the process () may act as disrupters of the hormonal and biochemical systems of aquatic organisms. The structure *Correspondingauthor. Tel.: +358-13-2513575; fax: +358- of phytosterols is similar to that of the hormones 13-2513590. of vertebrates. Transformation products of sterols, in E-mail address: jussi.kukkonen@joensuu.fi particular, can have adverse endocrine effects, andro- (J.V.K. Kukkonen). genic effects, on fish [12–14]. In addition, studies on the

0043-1354/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0043-1354(03)00108-8 2814 A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820 impacts of pulp mill effluents have been reported, for the hydraulic retention. Background information on the instance, stimulated growth and enzymatic induction samplings is presented in Table 1. [15–17], and decrease in levels of sex hormones and in Before the analyses, the wastewaters were filtered on reproductive capacity [12,18–20]. Transformation pro- Whatman GF-C filters. Solids in the water and dry ducts of sterols and resin acids can be formed during weights of the sludges were determined. Water and biological treatment of wastewater [13,14,17]. Possible particle samples were stored at À20C until analyzed. In transformation reactions are hydrogenation, hydroxyla- addition, the sludge samples were freeze-dried with a tion, decarboxylation and aromatization. Up to 40% of HETOSICC freeze-drier. Filtered water, solid matter the discharged compounds can be in the form of with the filter, and freeze-dried sludge samples were transformation products [13]. extracted accordingto Kaplin et al. [21]. Briefly, the The objective of this study was to analyze removal of water samples were extracted with hexane/EtOH (v/v: resin acids and plant sterols from effluent of an ECF 4/1) as solvent. The solid matter with filter and the kraft pulp mill by an activated sludge treatment plant. sludge samples were hydrolyzed with 0.5 M KOH in To get an overview of the performance of the treatment 90% EtOH and were then further extracted with diethyl plant, the samples were collected at different points in ether. Derivatized samples were analyzed semiquantita- the treatment process and duringdifferent runs of the tively with a Hewlett-Packard GC-MSD accompanied pulp mill. In addition to chemical analysis, the overall with an HP-1 column (25 m, i.d. 0.32 mm, film thickness bacterial toxicity of the samples was tested. 0.17 mm). The analyzed compounds are shown in Table 2. Of these compounds, and palustric acid, as well as 7-prenol and 24-methylene cycloartenol 2. Materials and methods overlapped. The internal standards used were heneico- sanoic acid (21:0) and cholesterol. Later in this article, Wastewater treatment plant of an ECF (O-Do-EOP- triterpenyl alcohols and are included in the D-D) kraft pulp mill located in eastern Finland was sterol group. sampled in order to study the fate of extractives and Dissolved organic carbon (DOC) was determined luminescence bacterial (V. fischeri) toxicity in different from the filtered water samples with a Shimadzu total parts of the plant (Fig. 1). In 1998, the pulp production organic carbon analyzer 5000A (Shimadzu, Kyoto, in this mill was 586 000 ADt/a; and the discharged loads Japan). In addition, total carbon contents of solid of COD, AOX, P and N were 7 640, 90, 2, and 39 t/a, matter and sludges were analyzed with a CHN- respectively. The pulp mill uses ca. 40 m3 water per ton analyzer (Carlo Erba Elemental Analyzer, Milano, of pulp produced. The samples were taken duringthree Italy). Bacterial (V. fischeri) toxicity and the EC50 different runs, twice in each. The runs were: (1) both values of the non-filtered effluents and sludges were fibrelines producingbirch pulp (Birch), (2) one line determined with a Flash-test [22] by Bio-Nobile Oy, producingbirch pulp and the other producingconifer Turku, Finland. The Flash-test is a kinetic direct- pulp (Norm), and (3) one line producingbirch and the contact luminescent bacterial test. The test is compar- other producing conifer pulp with a higher percentage of able to other bacterial tests (i.e. Microtox) and it is spruce (Reinf). Samplings were performed considering recommended for colored samples [22] because each

Debarking Activated sludge treatment Ecological pond Primary clarifier Secondary clarifiers

1 5 2 3 4

7 6 Sludge thickener 1 = mill inflow 2 = total effluent 3 = before activated sludge treatment 4 = secondary clarified water 5 = discharge 6 = primary sludge 7 = biosludge

Fig. 1. Sampling points. A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820 2815

Table 1 Production, proportion of birch and conifer pulp production, average wastewater flow, adsorbable organic carbon (AOX), chemical

(CODCr) and biological oxygen demand (BOD7), organic carbon (OC), dissolved organic carbon (DOC), and pH before (in) and after (out) the activated sludge treatment, total concentrations of nitrogen and phosphorous (totN and totP), and the amount of water solids at different samplingpoints

Birch/spruce Birch/conifer

Reinf1 Reinf2 Norm1 Norm2 Birch1 Birch2

Production, ADt/d 1945 1727 1986 1856 1638 1978 Birch/conifer, ADt/d 1315/630 1147/580 1363/623 1351/505 1638/0 1978/0 Average flow, m3/d 71 400 67 800 63 400 63 300 65 500 65 800 AOX, kg/d 258 230 240 240 230 230

CODCr in, mg/l 1658 2080 1602 1964 1492 2064 CODCr out, mg/l 364 308 323 342 272 302 BOD7 in, mg/l 459 675 569 621 496 599 BOD7 out, mg/l 7 7 6 7 6 8 DOC in, mg/l 282 430 388 486 483 361 DOC out, mg/l 143 168 142 130 304 123 OC in, mg/l 34.9 38.4 44.0 44.8 42.7 37.6 OC out, mg/l 14.3 14.6 13.9 14.9 13.6 14.9 totP out, mg/l 0.08 0.07 0.06 0.05 0.07 0.04 totN out, mg/l 1.37 1.23 1.61 0.84 2.2 1.46 pH in 6.1 6.0 7.6 6.2 6.5 6.9 pH out 8.0 8.2 8.0 8.0 8.0 8.0 Solids 2a, mg/l 219 244 265 267 590 690 Solids 3a, mg/l 81 129 85 129 112 84 Solids 5a, mg/l 5.4 6.8 5.0 1.2 4.0 4.8 Solids 6a, mg/l 7320 46 330 14 490 30 250 6950 33 850 Solids 7a, mg/l 5880 5720 4900 3800 6870 5440

a Number of a samplingpoint; see Fig. 1.

Table 2 Analyzed compounds

Resin acids Sterols Triterpenyl alcohols Hydrocarbon and prenol

Pimaranes Campesterol Lupeol Squalene Campestanol Methylbetulinate 7-prenol Sandaracopimaric acid b-sitosterol Betulinol Stigmastanol

Abietanes Cycloartenol Palustric acid Citrostadienol Levopimaric acid 24-methylene cycloartenol Dehydroabietic acid Neoabietic acid

sample acts as its own reference, and no correction for 3. Results color or turbidity is needed. The luminescence output of the samples, after addition of the bacteria, was first 3.1. Toxicity to Vibrio fisheri monitored for 30 s and then measured again after 30 min contact time. The results were calculated as EC50 values Toxicity (calculated as EC50 values) was found with both 30 s and 30 min contact times. Because 30 s mainly in samples taken before the activated sludge was not adequate for all samples to show toxicity, we treatment (samplingpoints 1–3, Table 3). The samples report here the EC50 values for 30 min contact time after the biotreatment were non-toxic as was the except for one sample set. biosludge (sampling point 7) itself. The most toxic 2816 A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820

Table 3 EC50 values (%) of the Flash-test for the six samplings with contact time 30 min

Samplingpoint Reinf1 Reinf2 Norm1 Norm2 Birch1 Birch2

(1) Mill inflow NDa ND ND 3.977.6 ND 4971.3 (2) Total effluent ND 3571.2 ND 1372.2 1971.4 1671.3 (3) Before As treat 4670.4 2871.2 ND 6.972.7 2571.6 1372.9 (4) Secondary clearout NTb ND NT NT ND NT (5) Discharge ND NT NT NT ND NT (6) Primary Sludge 2.770.2 1671.4 ND 1.5724 3.673.4 46716 (7) Biosludge NT NT NT NT NT NT

For Reinf2, the contact time was 30 s. a =inhibition o50%, EC50 value not determined. b =not toxic, inhibition negative. samples were found duringNorms 1 and 2 sampling Table 4 periods. Even though the inhibition remained under Total concentrations of (A) resin acids (B) sterols (g/t pulp) in 50% and EC50 values were not calculated for Norm1 particles and water in different parts of the wastewater samples, the toxic effect was very rapid. In all of the treatment plant samplings, the primary sludge was the most toxic sample Samplingpoint Reinf1 Reinf2 Norm1 Norm2 Birch1 Birch2 with EC50 values of 1.5–46%. The EC50 values varied between 13% and 35% in the total wastewaters before (A) Resin acids 1 46 129 289 60 44 178 primary clarification and between 6.9% and 46% in the 2 51 130 375 173 93 276 waters before biological treatment. In inflow water, in 3 16 58 162 34 41a 110 four samplings the inhibition with 30 min contact time 4 0.17 0.27 0.70 0.20 0.02a 0.22 was between 16% and 30%. Thus, in two samplings 5 0.19 0.19 0.89 0.17 0.10 0.15 inhibition exceeded 50%, and the EC50 values were 6 2.3 30 47 85 0.54 72 calculated. These findings suggest that the debarking 7 20 43 838 46 28 60 effluents might be the reason for toxicity of the total effluent at samplingpoint 2. In general,at each sampling (B) Sterols point, the variation between different samplings was 1 36 112 190 58 102 108 large. 2 49 137 172 82 123 171 38662915985a 86 4 1.1 1.6 1.2 0.99 0.12a 1.0 3.2. Wood extractives 5 0.19 0.19 0.71 0.17 0.44 0.15 6 10 76 67 177 2.5 217 In this study, the decrease in the concentrations of the 7 657 1017 1259 851 1083 1345 analyzed compounds duringactivated sludgetreatment a =concentration in water only. was over 97% (Table 4, Fig. 2). At the discharge point, the total concentrations of resin acids varied between 2 and 29 mg/l and those of sterols between 11 and 45 mg/l. Relative to flow and pulp production, the concentra- the inflow was lowest in the Birch1 run and for the tions were 0.10–0.89 and 0.15–0.71 g/t, respectively sterols in the Reinf1 run. Before biotreatment, compared (Table 4). At the discharge point, the resin acid to the situation in the discharged water, the amount of concentration was highest during the Norm1 run and extractives in water was higher than in the particles. In the sterol concentration was highest during the Reinf2 the sludges, the resin acid concentrations in the primary run. Discharge was lowest in Birch1 sampling. Of the sludge were 0.1–4.9 mg/g sludge, and in the biosludge total amount of wood extractives discharged, about 0.1–5.3 mg/g. The sterol concentrations of the sludge 80% were adsorbed to solid matter and 20% were were 1.4–8.9 and 4.4–8.9 mg/g, respectively. Overflow of dissolved in the water phase. Thus, large amount of solid the sludge thickener increased the concentrations of matter was correlated to the high concentrations of resin acids and sterols in the sludges. In primary sludge, extractives in samples. the daily removal of resin acids was 0.5–85 g/t and that Both the resin acid and the sterol load comingto the of sterols 2.5–217 g/t. Correspondingly, removal from wastewater treatment was highest in the Norm1 run the biosludge to the sludge thickener was 0.9–35 and 27– (Table 4). Duringthat sampling,both particles and 52 g/t, respectively. water contained the most extractives compared to the The most abundant pimarane was isopimaric acid, other samplings. For the resin acids the concentration in and the most abundant were DHAA and A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820 2817

Fig. 2. Trends for resin acids and sterols (g/t pulp) in the wastewater treatment plant of an ECF kraft pulp mill (samplingpoints 1–5; see Fig. 1) duringdifferent samplings.

abietic acid. Of the total resin acids, abietanes covered o1% of the total sterols both in water and in particles, 90% in the water and 94% in the particles before, and and after biotreatment increased to 9% and 2%, 81% and 96%, respectively, after biotreatment. In both respectively. In addition, in the sludges the correspond- sludges, the proportion of abietanes was 96%. The most ingproportion was also o1% of the total sterols. abundant sterols were b-sitosterol and citrostadienol, After primary clarification, over 40% of the resin and the dominant triterpenyl alcohol was betulinol. Of acids and over 36% of the sterols went further to the the sterol group, triterpenyl alcohols covered, on biotreatment. In the activated sludge treatment, the average, 26% in water and 60% in particles before, amount of degraded or transformed resin acids exceeded and 9% and 48%, respectively, after the biotreatment. 94% in all samplings except in Norm1, where it was In sludges, the proportion was 66%. Betulinol, which 78% (Table 5). In that sampling, the amount removed to originates from birch bark, was not present in high biosludge was 22%, while in the other samplings it was concentrations duringthe Birch runs as had been 2.3–5.6%. The sterol group varied more than the resin expected. Before the biotreatment, squalene made up acids did. Of the sterols, 41–67% were degraded or 2818 A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820

Table 5 because of the mixingof wood species. Moreover, for Fate of (A) resin acids and (B) sterols in activated sludge the Norm2 samples, neither the CODCr and BOD7 treatment plant; degradation or transformation (degr/transf), values nor the concentrations of wood extractives were removal with sludge and amount going forward to the correlated with toxicity. ecological pool (forward) (%)

Degr/transf Removal Forward 4.2. Wood extractives

(A) Resin acids The activated sludge plant removes significant Reinf1 94 5.4 1.1 Reinf2 96 3.1 0.5 amounts of wood extractives from the pulp mill effluent Norm1 78 22 0.4 [7,9,21]. In this study, the reductions were similar to Norm2 94 5.6 0.6 those found in an earlier study [21]. However, the Birch1 97 2.9 0.2 discharged concentrations were lower than in those Birch2 98 2.3 0.2 reported in the beginning of the 1990s [5,28]. Although the total concentrations of resin acids were (B) Sterols lower than the concentrations that are acutely toxic to Reinf1 67 31 1.3 fish, the highest concentrations measured were on a level Reinf2 53 43 3.7 that can cause physiological effects in fish. For example, Norm1 41 57 1.4 20 mg/l dehydroabietic acid (DHAA) has been reported Norm2 59 39 1.8 Birch1 47 53 0.5 to have subchronic effects on fish [8]. The LC50 values Birch2 63 36 0.9 (2.3–21 mg/l) determined earlier for resin acids with the luminescent bacteria (Vibrio fisheri) test [10] was not exceeded in any of the samples. Mattson et al. [16] transformed and 31–57% were removed with the sludge reported that 10 mg/l exposure to phytosterols, accumu- to the thickener. In the ecological pool, no more lated via the mother, already has an effect on fish larvae, extractives were removed. stimulatingtheir growth.Duringexposure to treated effluent, juvenile rainbow trouts also grew more [17].In addition to the effect on growth, disturbance of 4. Discussion endocrine mechanisms affects both metabolism and reproduction [20]. Decreased reproductive capacity is 4.1. Toxicity to Vibrio fisheri mainly due to the lower level of sex in the parent fish and the effect of sterols on vitellogenesis [15].It In previously reported bacterial toxicity tests, at the should be noted, however, that at the discharge point the same mill as studied here with ECF or TCF bleaching effluent is diluted considerably. and hardwood or softwood, the EC50 values found for Even though over 90% of the resin acids analyzed untreated effluents were 15–45% [5]. In addition, in here are removed in biotreatment, the residue discharged another Finnish mill with ECF bleachingand both can still be toxic to aquatic organisms [9]. Of the reduced hardwood and softwood, the EC50 values for untreated 90%, 40% may consist of biotransformed forms of resin effluents were 2–15% [10]. In Sweden, for an ECF mill acids, such as decarboxylated resin acid hydrocarbons, usingsoftwood the reported EC50 value was 31% [23]. partially or fully saturated resin acids and oxygenated The previous findings are in accordance with the results resin acids [13]. Studies on sterols have shown that they of our study. It has been elicited that effluent toxicity, are more likely to be biotransformed by bacteria than to and especially the toxicity of resin acids, is dependent on degrade [1,17]. Moreover, the transformation products pH [6,9]. In this study, however, the pH of the inflow can cause the effects mentioned above. sample was 6.0–6.9 for all samplings except for Norm1 The different samplings were not directly comparable. for which the pH was 7.6. Thus, the toxicity of the Both the concentrations and the production were Norm2 sample from the inflow cannot be explained by highest during the Norm1 sampling (Tables 1 and 4). the pH, which was 6.2. Debarkingeffluents have been The high concentrations were mainly due to 1-day reported to be toxic to bacteria [11], which might be the shutdown of the mill. The overflow of the sludge thick- reason for the toxicity of the total effluent (sampling ener influenced the amount of water solids (Table 1) point 2) in this study. Stuthridge and Tavendale [13] and the concentrations of extractives at samplingpoints found that 60–90% of the effluent toxicity originates no. 2, 3, and 6 (Table 4) duringsamplingsNorm1 and 2, from resin acids. It has also been reported that the Birch2, and Reinf2, but did not affect the efficiency of species of wood can affect effluent toxicity [24–26]. the activated sludge treatment plant, nor did the 1-day Softwood has been found to be more toxic than shutdown. This was due to efficient adsorption of wood hardwood to fish [24] and to P. phosphoreum [27].No extractives onto the biosludge (Table 5). However, the such effect can be found in the results of this study concentrations of CODCr or BOD7 were effected only by A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820 2819 overflow of the sludge thickener, not the shutdown of [7] Easty DB, Borchardt LG, Wabers BA. Wood derived toxic the mill (Table 1). compounds: removal from mill effluents by waste treat- ment processes. Tappi 1978;61:57–60. [8] Oikari A, Lonn. B-E, Castren! M, Nakari T, Snickars- Nikinmaa B, Bister H, Virtanen E. Toxicological effects 5. Conclusions of dehydroabietic acid (DHAA) on the trout, Salmo gairdneri Richardson, in fresh water. Water Res 1983;17: Both the performance and the operation stability of 81–9. the activated sludge treatment plant were good. Even [9] Werker AG, Hall ER. The influence of pH on the growth- though the different sample series were not fully linked biodegradation kinetics of selected resin acids found comparable, the disturbingfactors that increased the in pulp mill effluent. TAPPI J 1999;82:169–77. [10] Verta M, Ahtiainen J, Nakart T, Langi A, Talka E. The load of wood extractives did not affect the operation effect of waste constituents on the toxicity of TCF and efficiency of the secondary treatment system. However, ECF pulp bleachingeffluents. In: Servos MR, Munkittrick the concentrations of wood extractives in the discharged KR, Carey JH, Van Der Kraak G, editors. Environmental water were still at a level that can have subchronic fate and effects of pulp and paper mill effluents. Delray effects on organisms living in the water. Most of the Beach, FL: St. Lucie Press, 1996. extractives were discharged attached to particles. Thus, [11] Ahtiainen J, Ruoppa M, Nakari T, Verta M. Toxicity a main conclusion of this work is that, by improvingthe screeningof novel pulpinginfluents and effluents in removal of fine particles, the removal of wood extrac- Finnish pulp mills. In: Servos MR, Munkittrick KR, tives can be even further improved. Carey JH, Van Der Kraak G, editors. Environmental fate and effects of pulp and paper mill effluents. Delray Beach, FL: St. Lucie Press, 1996. [12] Tatum VL, Fisher RP. The endocrine active chemicals Acknowledgements issue. TAPPI Environmental, , 1995. [13] Stuthridge TR, Tavendale MH. Biotransformation and This study was financed by the National partitioningof resin acids within an aerated stabilization basin. TAPPI Proceedings, 1995. Agency (TEKES), Stora-Enso Oyj and Aquaflow [14] Stahlschmidt-Allner P, Allner B, Rombke. J, Knacker T. Oy. We acknowledge Eeva Punta and Petri Lassila ( Endocrine distrupters in the aquatic environment. Environ (Enocell Oy), Eija Bergelin and Camilla Kaplin (Abo Sci Pollut Res 1997;4:155–62. Akademi) for their co-operation and Prof. Bjarne . ( [15] Lehtinen K-J, Mattson K, Tana J, Engstrom C, Lerche O, Holmbom (Abo Akademi) for valuable discussions HemmingJ. Effects of wood-related sterols on the and comments duringthe project. We also acknowledge, reproduction, egg survival, and offspring of brown trout Risto Juvonen (Bio-Nobile Oy) for comments on the (Salmo trutta lacustris L.). Ecotoxicol Environ Saf 1999; toxicity tests. 42:40–9. [16] Mattson K, Lehtinen K-J, Tana J, HardingJ,. Kukkonen J, Nakari T, Engstrom. C. Effects of pulp mill effluents and restricted diet on growth and physiology of rainbow trout References (Oncorhynchus mykiss). Ecotoxicol Environ Saf 2001;49: 144–54. [1] Tana J, Lehtinen K-J. Valkaistun massan tuotannosta [17] Mattson K, Tana J, Engstrom. C, HemmingJ, Lehtinen K- aiheutuvien jatevesien. ymparist. ovaikutusten. arviointi - J. Effects of wood-related sterols on the offspringof the yleiskatsaus. Suomen ymparist. okeskus,. 1996. viviparous blenny, Zoarces viviparus L. Ecotoxicol Envir- [2] Ekman R, Holmbom B. Analysis by gas chromatography on Saf 2001;49:122–30. of the wood extractives in pulp and water samples from [18] Tremblay L, Van Der Kraak G. Comparison between the mechanical pulpingof spruce. Nord Pulp Pap Res J 1989; effects of the b-sitosterol and pulp and paper 4:16–24. mill effluents on sexually immature rainbow trout. Environ [3] Axegard( P, Dahlman O, Hagling I, Jacobson B, Morck. R, Toxicol Chem 1999;18:329–36. StrombergL.. Pulp bleachingand the environment— [19] Van Der Kraak GJ, Munkittrick KR, McMaster ME, the situation in 1993. Nord Pulp Pap Res J 1993;8: Portt CB, ChangJP. Exposure to bleached kraft pulp mill 365–78. effluent disrupts the pituitary-gonad axis of white sucker at [4] Saunamaki. R. Biological waste water treatment in the multiple sites. Ecotoxicol Appl Pharmacol 1992;115: Finnish . Pap Timber 1989;2: 224–33. 158–64. [20] McMaster ME, Van Der Kraak GJ, Munkittrick KR. An [5] Punta E, Suppola J. Toxicity reduction of a modern epidemiological evaluation of the biochemical basis for Finnish bleached kraft pulp mill by effluent treatment steroid hormonal depressions in fish exposed to industrial plant. Atlanta: TAPPI Environmental, 1995. wastes. J Great Lakes Res 1996;22:153–71. [6] Kovacs TG, Voss RH. Biological and chemical character- [21] Kaplin C, Holmbom B, Huhtiniemi M. Removal and ization of /specialty mill effluents. Water Res degradation of wood resin components in an activated 1992;26:771–80. sludge treatment plant. Proceedings of the third Interna- 2820 A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820

tional Conference on Environmental Fate and Effects of Environmental fate and effects of pulp and paper mill Pulp and Paper Mill Effluents, PAPRO, Rotorua, NZ, effluents. Delray Beach, FL: St. Lucie Press, 1996. 2003. p. 146–152, in press. [25] Leach JM, Thakore AN. Toxic constituents in mechanical [22] Lappalainen J, Juvonen R, Vaajasaari K, Karp M. A New pulpingeffluents. Tappi 1976;59:129–32. Flash method for measuringthe toxicity of solid and [26] Oconnor BI, Kovacs TG, Voss RH. The effect of wood colored samples. Chemosphere 1999;38:1069–83. species composition on the toxicity of simulated mechan- [23] Tarkpea M, Eklund B, Linde M, Bengtsson B-E. Toxicity ical pulpingeffluents. Environ Toxicol Chem 1992;11: of conventional, elemental chlorine-free, and totally 1259–70. chlorine-free kraft-pulp bleachingeffluents assessed by [27] Cates DH, Eggert C, Yang JL, Eriksson K-EL. Compar- short-term lethal and sublethal bioassays. Environ Toxicol ison of effluents from TCF and ECF bleachingof kraft Chem 1999;18:2487–96. pulps. Tappi J 1995;78:93–8. [24] Ruonala S, Lammi R. Environmental impacts of pulp [28] Tana J. Puuperaiset. uuteaineet Enocell Oy:n ulosmenev- bleachingbased on oxygenchemicals. In: Servos MR, ass. aj. atevedess. a.. Suomen Ymparist. oTutkijaryhm. a. Oy, Munkittrick KR, Carey JH, Van Der Kraak G, editors. 1993.