- Email: [email protected]
Removal of resin acids and sterols from pulp mill effluents by activated sludge treatment
Water Research 37 (2003) 2813–2820
Removal of resin acids and sterols from pulp 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 elemental chlorine free bleaching kraft pulp mill located in eastern Finland was sampled in order to study the fate of wood 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. During wastewater 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 After changes in the bleaching processes, research on pulp mill effluents has expanded from chlorinated compounds to wood extractives such as resin acids and sterols [1]. These extractives cause foaming problems and are impurities in the products and on the equipment of pulp and paper mills [2]. Since the early 1990s, the use of ECF bleaching techniques has become common, replacing the use of chlorine gas [3]. Moreover, in the 1980s, the introduction of activated sludge wastewater treatment has reduced BOD in effluents by 85–95% and COD by 40–80% [4]. Other improvements in the process *Corresponding author. Tel.: +358-13-2513575; fax: +35813-2513590. E-mail address: jussi.kukkonen@joensuu.fi (J.V.K. Kukkonen).
have also reduced the load: modified cooking, oxygen delignification, more effective washing of pulp and more closed water circulation [1,3,5]. Secondary treatment of pulp mill effluents reduces, in addition to BOD and COD, the toxicity of effluents [4,6]. Many studies have found resin acids and unsaturated fatty acids toxic to aquatic organisms, and various methods have been used to test toxicity [7–9]. Recently, bacterial testing has become popular because it is sensitive and relatively quick and easy to perform [6,10,11]. Quite recently, it has been shown that plant sterols (phytosterols) may act as disrupters of the hormonal and biochemical systems of aquatic organisms. The structure of phytosterols is similar to that of the steroid hormones of vertebrates. Transformation products of sterols, in particular, can have adverse endocrine effects, androgenic 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
A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820
2814
impacts of pulp mill effluents have been reported, for instance, stimulated growth and enzymatic induction [15–17], and decrease in levels of sex hormones and in reproductive capacity [12,18–20]. Transformation products of sterols and resin acids can be formed during biological treatment of wastewater [13,14,17]. Possible transformation reactions are hydrogenation, hydroxylation, decarboxylation and aromatization. Up to 40% of the discharged compounds can be in the form of transformation products [13]. The objective of this study was to analyze removal of resin acids and plant sterols from effluent of an ECF kraft pulp mill by an activated sludge treatment plant. To get an overview of the performance of the treatment plant, the samples were collected at different points in the treatment process and during different runs of the pulp mill. In addition to chemical analysis, the overall bacterial toxicity of the samples was tested.
2. Materials and methods Wastewater treatment plant of an ECF (O-Do-EOPD-D) kraft pulp mill located in eastern Finland was sampled in order to study the fate of extractives and luminescence bacterial (V. fischeri) toxicity in different parts of the plant (Fig. 1). In 1998, the pulp production in this mill was 586 000 ADt/a; and the discharged loads of COD, AOX, P and N were 7 640, 90, 2, and 39 t/a, respectively. The pulp mill uses ca. 40 m3 water per ton of pulp produced. The samples were taken during three different runs, twice in each. The runs were: (1) both fibrelines producing birch pulp (Birch), (2) one line producing birch pulp and the other producing conifer pulp (Norm), and (3) one line producing birch and the other producing conifer pulp with a higher percentage of spruce (Reinf). Samplings were performed considering
Debarking
Activated sludge treatment
Ecological pond Secondary clarifiers
Primary clarifier
1
the hydraulic retention. Background information on the samplings is presented in Table 1. Before the analyses, the wastewaters were filtered on Whatman GF-C filters. Solids in the water and dry weights of the sludges were determined. Water and particle samples were stored at 20 C until analyzed. In addition, the sludge samples were freeze-dried with a HETOSICC freeze-drier. Filtered water, solid matter with the filter, and freeze-dried sludge samples were extracted according to Kaplin et al. [21]. Briefly, the water samples were extracted with hexane/EtOH (v/v: 4/1) as solvent. The solid matter with filter and the sludge samples were hydrolyzed with 0.5 M KOH in 90% EtOH and were then further extracted with diethyl ether. Derivatized samples were analyzed semiquantitatively with a Hewlett-Packard GC-MSD accompanied with an HP-1 column (25 m, i.d. 0.32 mm, film thickness 0.17 mm). The analyzed compounds are shown in Table 2. Of these compounds, levopimaric acid and palustric acid, as well as 7-prenol and 24-methylene cycloartenol overlapped. The internal standards used were heneicosanoic acid (21:0) and cholesterol. Later in this article, triterpenyl alcohols and squalene are included in the sterol group. Dissolved organic carbon (DOC) was determined from the filtered water samples with a Shimadzu total organic carbon analyzer 5000A (Shimadzu, Kyoto, Japan). In addition, total carbon contents of solid matter and sludges were analyzed with a CHNanalyzer (Carlo Erba Elemental Analyzer, Milano, Italy). Bacterial (V. fischeri) toxicity and the EC50 values of the non-filtered effluents and sludges were determined with a Flash-test [22] by Bio-Nobile Oy, Turku, Finland. The Flash-test is a kinetic directcontact luminescent bacterial test. The test is comparable to other bacterial tests (i.e. Microtox) and it is recommended for colored samples [22] because each
4
3
2
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.
5
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 sampling points Birch/spruce
Production, ADt/d Birch/conifer, ADt/d Average flow, m3/d AOX, kg/d CODCr in, mg/l CODCr out, mg/l BOD7 in, mg/l BOD7 out, mg/l DOC in, mg/l DOC out, mg/l OC in, mg/l OC out, mg/l totP out, mg/l totN out, mg/l pH in pH out Solids 2a, mg/l Solids 3a, mg/l Solids 5a, mg/l Solids 6a, mg/l Solids 7a, mg/l a
Birch/conifer
Reinf1
Reinf2
Norm1
Norm2
Birch1
Birch2
1945 1315/630 71 400 258 1658 364 459 7 282 143 34.9 14.3 0.08 1.37 6.1 8.0 219 81 5.4 7320 5880
1727 1147/580 67 800 230 2080 308 675 7 430 168 38.4 14.6 0.07 1.23 6.0 8.2 244 129 6.8 46 330 5720
1986 1363/623 63 400 240 1602 323 569 6 388 142 44.0 13.9 0.06 1.61 7.6 8.0 265 85 5.0 14 490 4900
1856 1351/505 63 300 240 1964 342 621 7 486 130 44.8 14.9 0.05 0.84 6.2 8.0 267 129 1.2 30 250 3800
1638 1638/0 65 500 230 1492 272 496 6 483 304 42.7 13.6 0.07 2.2 6.5 8.0 590 112 4.0 6950 6870
1978 1978/0 65 800 230 2064 302 599 8 361 123 37.6 14.9 0.04 1.46 6.9 8.0 690 84 4.8 33 850 5440
Number of a sampling point; see Fig. 1.
Table 2 Analyzed compounds Resin acids
Sterols
Triterpenyl alcohols
Hydrocarbon and prenol
Pimaranes Pimaric acid Sandaracopimaric acid Isopimaric acid
Campesterol Campestanol b-sitosterol Stigmastanol
Lupeol Methylbetulinate Betulinol
Squalene 7-prenol
Abietanes Palustric acid Levopimaric acid Dehydroabietic acid Neoabietic acid Abietic acid
Cycloartenol Citrostadienol 24-methylene cycloartenol
sample acts as its own reference, and no correction for color or turbidity is needed. The luminescence output of the samples, after addition of the bacteria, was first monitored for 30 s and then measured again after 30 min contact time. The results were calculated as EC50 values with both 30 s and 30 min contact times. Because 30 s was not adequate for all samples to show toxicity, we report here the EC50 values for 30 min contact time except for one sample set.
3. Results 3.1. Toxicity to Vibrio fisheri Toxicity (calculated as EC50 values) was found mainly in samples taken before the activated sludge treatment (sampling points 1–3, Table 3). The samples after the biotreatment were non-toxic as was the 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 Sampling point (1) (2) (3) (4) (5) (6) (7)
Mill inflow Total effluent Before As treat Secondary clearout Discharge Primary Sludge Biosludge
Reinf1 a
ND ND 4670.4 NTb ND 2.770.2 NT
Reinf2
Norm1
Norm2
Birch1
Birch2
ND 3571.2 2871.2 ND NT 1671.4 NT
ND ND ND NT NT ND NT
3.977.6 1372.2 6.972.7 NT NT 1.5724 NT
ND 1971.4 2571.6 ND ND 3.673.4 NT
4971.3 1671.3 1372.9 NT NT 46716 NT
For Reinf2, the contact time was 30 s. a =inhibition o50%, EC50 value not determined. b =not toxic, inhibition negative.
samples were found during Norms 1 and 2 sampling periods. Even though the inhibition remained under 50% and EC50 values were not calculated for Norm1 samples, the toxic effect was very rapid. In all of the samplings, the primary sludge was the most toxic sample with EC50 values of 1.5–46%. The EC50 values varied between 13% and 35% in the total wastewaters before primary clarification and between 6.9% and 46% in the waters before biological treatment. In inflow water, in four samplings the inhibition with 30 min contact time was between 16% and 30%. Thus, in two samplings inhibition exceeded 50%, and the EC50 values were calculated. These findings suggest that the debarking effluents might be the reason for toxicity of the total effluent at sampling point 2. In general, at each sampling point, the variation between different samplings was large. 3.2. Wood extractives In this study, the decrease in the concentrations of the analyzed compounds during activated sludge treatment 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 concentrations were 0.10–0.89 and 0.15–0.71 g/t, respectively (Table 4). At the discharge point, the resin acid concentration was highest during the Norm1 run and the sterol concentration was highest during the Reinf2 run. Discharge was lowest in Birch1 sampling. Of the total amount of wood extractives discharged, about 80% were adsorbed to solid matter and 20% were dissolved in the water phase. Thus, large amount of solid matter was correlated to the high concentrations of extractives in samples. Both the resin acid and the sterol load coming to the wastewater treatment was highest in the Norm1 run (Table 4). During that sampling, both particles and water contained the most extractives compared to the other samplings. For the resin acids the concentration in
Table 4 Total concentrations of (A) resin acids (B) sterols (g/t pulp) in particles and water in different parts of the wastewater treatment plant Sampling point Reinf1 Reinf2 Norm1 Norm2 Birch1 (A) Resin acids 1 46 129 2 51 130 3 16 58 4 0.17 0.27 5 0.19 0.19 6 2.3 30 7 20 43 (B) Sterols 1 2 3 4 5 6 7 a
289 60 375 173 162 34 0.70 0.20 0.89 0.17 47 85 838 46
Birch2
44 178 93 276 41a 110 0.02a 0.22 0.10 0.15 0.54 72 28 60
36 112 190 58 102 108 49 137 172 82 123 171 86 62 91 59 85a 86 1.1 1.6 1.2 0.99 0.12a 1.0 0.19 0.19 0.71 0.17 0.44 0.15 10 76 67 177 2.5 217 657 1017 1259 851 1083 1345
=concentration in water only.
the inflow was lowest in the Birch1 run and for the sterols in the Reinf1 run. Before biotreatment, compared to the situation in the discharged water, the amount of extractives in water was higher than in the particles. In the sludges, the resin acid concentrations in the primary sludge were 0.1–4.9 mg/g sludge, and in the biosludge 0.1–5.3 mg/g. The sterol concentrations of the sludge were 1.4–8.9 and 4.4–8.9 mg/g, respectively. Overflow of the sludge thickener increased the concentrations of resin acids and sterols in the sludges. In primary sludge, the daily removal of resin acids was 0.5–85 g/t and that of sterols 2.5–217 g/t. Correspondingly, removal from the biosludge to the sludge thickener was 0.9–35 and 27– 52 g/t, respectively. The most abundant pimarane was isopimaric acid, and the most abundant abietanes 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 (sampling points 1–5; see Fig. 1) during different samplings.
abietic acid. Of the total resin acids, abietanes covered 90% in the water and 94% in the particles before, and 81% and 96%, respectively, after biotreatment. In both sludges, the proportion of abietanes was 96%. The most abundant sterols were b-sitosterol and citrostadienol, and the dominant triterpenyl alcohol was betulinol. Of the sterol group, triterpenyl alcohols covered, on average, 26% in water and 60% in particles before, and 9% and 48%, respectively, after the biotreatment. In sludges, the proportion was 66%. Betulinol, which originates from birch bark, was not present in high concentrations during the Birch runs as had been expected. Before the biotreatment, squalene made up
o1% of the total sterols both in water and in particles, and after biotreatment increased to 9% and 2%, respectively. In addition, in the sludges the corresponding proportion was also o1% of the total sterols. After primary clarification, over 40% of the resin acids and over 36% of the sterols went further to the biotreatment. In the activated sludge treatment, the amount of degraded or transformed resin acids exceeded 94% in all samplings except in Norm1, where it was 78% (Table 5). In that sampling, the amount removed to biosludge was 22%, while in the other samplings it was 2.3–5.6%. The sterol group varied more than the resin acids did. Of the sterols, 41–67% were degraded or
A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820
2818
Table 5 Fate of (A) resin acids and (B) sterols in activated sludge treatment plant; degradation or transformation (degr/transf), removal with sludge and amount going forward to the ecological pool (forward) (%) Degr/transf
Removal
Forward
(A) Resin acids Reinf1 94 Reinf2 96 Norm1 78 Norm2 94 Birch1 97 Birch2 98
5.4 3.1 22 5.6 2.9 2.3
1.1 0.5 0.4 0.6 0.2 0.2
(B) Sterols Reinf1 Reinf2 Norm1 Norm2 Birch1 Birch2
31 43 57 39 53 36
1.3 3.7 1.4 1.8 0.5 0.9
67 53 41 59 47 63
transformed and 31–57% were removed with the sludge to the thickener. In the ecological pool, no more extractives were removed.
4. Discussion 4.1. Toxicity to Vibrio fisheri In previously reported bacterial toxicity tests, at the same mill as studied here with ECF or TCF bleaching and hardwood or softwood, the EC50 values found for untreated effluents were 15–45% [5]. In addition, in another Finnish mill with ECF bleaching and both hardwood and softwood, the EC50 values for untreated effluents were 2–15% [10]. In Sweden, for an ECF mill using softwood the reported EC50 value was 31% [23]. The previous findings are in accordance with the results of our study. It has been elicited that effluent toxicity, and especially the toxicity of resin acids, is dependent on pH [6,9]. In this study, however, the pH of the inflow sample was 6.0–6.9 for all samplings except for Norm1 for which the pH was 7.6. Thus, the toxicity of the Norm2 sample from the inflow cannot be explained by the pH, which was 6.2. Debarking effluents have been reported to be toxic to bacteria [11], which might be the reason for the toxicity of the total effluent (sampling point 2) in this study. Stuthridge and Tavendale [13] found that 60–90% of the effluent toxicity originates from resin acids. It has also been reported that the species of wood can affect effluent toxicity [24–26]. Softwood has been found to be more toxic than hardwood to fish [24] and to P. phosphoreum [27]. No such effect can be found in the results of this study
because of the mixing of wood species. Moreover, for the Norm2 samples, neither the CODCr and BOD7 values nor the concentrations of wood extractives were correlated with toxicity. 4.2. Wood extractives The activated sludge plant removes significant amounts of wood extractives from the pulp mill effluent [7,9,21]. In this study, the reductions were similar to those found in an earlier study [21]. However, the discharged concentrations were lower than in those reported in the beginning of the 1990s [5,28]. Although the total concentrations of resin acids were lower than the concentrations that are acutely toxic to fish, the highest concentrations measured were on a level that can cause physiological effects in fish. For example, 20 mg/l dehydroabietic acid (DHAA) has been reported to have subchronic effects on fish [8]. The LC50 values (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] reported that 10 mg/l exposure to phytosterols, accumulated via the mother, already has an effect on fish larvae, stimulating their growth. During exposure to treated effluent, juvenile rainbow trouts also grew more [17]. In addition to the effect on growth, disturbance of endocrine mechanisms affects both metabolism and reproduction [20]. Decreased reproductive capacity is mainly due to the lower level of sex steroids in the parent fish and the effect of sterols on vitellogenesis [15]. It should be noted, however, that at the discharge point the effluent is diluted considerably. Even though over 90% of the resin acids analyzed here are removed in biotreatment, the residue discharged can still be toxic to aquatic organisms [9]. Of the reduced 90%, 40% may consist of biotransformed forms of resin acids, such as decarboxylated resin acid hydrocarbons, partially or fully saturated resin acids and oxygenated resin acids [13]. Studies on sterols have shown that they are more likely to be biotransformed by bacteria than to degrade [1,17]. Moreover, the transformation products can cause the effects mentioned above. The different samplings were not directly comparable. Both the concentrations and the production were highest during the Norm1 sampling (Tables 1 and 4). The high concentrations were mainly due to 1-day shutdown of the mill. The overflow of the sludge thickener influenced the amount of water solids (Table 1) and the concentrations of extractives at sampling points no. 2, 3, and 6 (Table 4) during samplings Norm1 and 2, Birch2, and Reinf2, but did not affect the efficiency of the activated sludge treatment plant, nor did the 1-day shutdown. This was due to efficient adsorption of wood extractives onto the biosludge (Table 5). However, the concentrations of CODCr or BOD7 were effected only by
A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820
overflow of the sludge thickener, not the shutdown of the mill (Table 1).
5. Conclusions Both the performance and the operation stability of the activated sludge treatment plant were good. Even though the different sample series were not fully comparable, the disturbing factors that increased the load of wood extractives did not affect the operation efficiency of the secondary treatment system. However, the concentrations of wood extractives in the discharged water were still at a level that can have subchronic effects on organisms living in the water. Most of the extractives were discharged attached to particles. Thus, a main conclusion of this work is that, by improving the removal of fine particles, the removal of wood extractives can be even further improved.
Acknowledgements This study was financed by the National Technology Agency (TEKES), Stora-Enso Oyj and Aquaflow Oy. We acknowledge Eeva Punta and Petri Lassila ( (Enocell Oy), Eija Bergelin and Camilla Kaplin (Abo Akademi) for their co-operation and Prof. Bjarne ( Holmbom (Abo Akademi) for valuable discussions and comments during the project. We also acknowledge, Risto Juvonen (Bio-Nobile Oy) for comments on the toxicity tests.
References [1] Tana J, Lehtinen K-J. Valkaistun massan tuotannosta . aiheutuvien j.atevesien ymp.aristovaikutusten arviointi . yleiskatsaus. Suomen ymp.aristokeskus, 1996. [2] Ekman R, Holmbom B. Analysis by gas chromatography of the wood extractives in pulp and water samples from mechanical pulping of spruce. Nord Pulp Pap Res J 1989; 4:16–24. . [3] Axeg(ard P, Dahlman O, Hagling I, Jacobson B, Morck R, . Stromberg L. Pulp bleaching and the environment— the situation in 1993. Nord Pulp Pap Res J 1993;8: 365–78. [4] Saunam.aki R. Biological waste water treatment in the Finnish pulp and paper industry. Pap Timber 1989;2: 158–64. [5] Punta E, Suppola J. Toxicity reduction of a modern Finnish bleached kraft pulp mill by effluent treatment plant. Atlanta: TAPPI Environmental, 1995. [6] Kovacs TG, Voss RH. Biological and chemical characterization of newsprint/specialty mill effluents. Water Res 1992;26:771–80.
2819
[7] Easty DB, Borchardt LG, Wabers BA. Wood derived toxic compounds: removal from mill effluents by waste treatment processes. Tappi 1978;61:57–60. . [8] Oikari A, Lonn B-E, Castr!en M, Nakari T, SnickarsNikinmaa B, Bister H, Virtanen E. Toxicological effects of dehydroabietic acid (DHAA) on the trout, Salmo gairdneri Richardson, in fresh water. Water Res 1983;17: 81–9. [9] Werker AG, Hall ER. The influence of pH on the growthlinked biodegradation kinetics of selected resin acids found in pulp mill effluent. TAPPI J 1999;82:169–77. [10] Verta M, Ahtiainen J, Nakart T, Langi A, Talka E. The effect of waste constituents on the toxicity of TCF and ECF pulp bleaching effluents. In: Servos MR, Munkittrick KR, Carey JH, Van Der Kraak G, editors. Environmental fate and effects of pulp and paper mill effluents. Delray Beach, FL: St. Lucie Press, 1996. [11] Ahtiainen J, Ruoppa M, Nakari T, Verta M. Toxicity screening of novel pulping influents and effluents in Finnish pulp mills. In: Servos MR, Munkittrick KR, 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 issue. TAPPI Environmental, Canada, 1995. [13] Stuthridge TR, Tavendale MH. Biotransformation and partitioning of resin acids within an aerated stabilization basin. TAPPI Proceedings, 1995. . [14] Stahlschmidt-Allner P, Allner B, Rombke J, Knacker T. Endocrine distrupters in the aquatic environment. Environ Sci Pollut Res 1997;4:155–62. . C, Lerche O, [15] Lehtinen K-J, Mattson K, Tana J, Engstrom Hemming J. Effects of wood-related sterols on the reproduction, egg survival, and offspring of brown trout (Salmo trutta lacustris L.). Ecotoxicol Environ Saf 1999; 42:40–9. [16] Mattson K, Lehtinen K-J, Tana J, H.arding J, Kukkonen J, . C. Effects of pulp mill effluents and Nakari T, Engstrom restricted diet on growth and physiology of rainbow trout (Oncorhynchus mykiss). Ecotoxicol Environ Saf 2001;49: 144–54. . C, Hemming J, Lehtinen K[17] Mattson K, Tana J, Engstrom J. Effects of wood-related sterols on the offspring of the viviparous blenny, Zoarces viviparus L. Ecotoxicol Environ Saf 2001;49:122–30. [18] Tremblay L, Van Der Kraak G. Comparison between the effects of the phytosterol b-sitosterol and pulp and paper mill effluents on sexually immature rainbow trout. Environ Toxicol Chem 1999;18:329–36. [19] Van Der Kraak GJ, Munkittrick KR, McMaster ME, Portt CB, Chang JP. Exposure to bleached kraft pulp mill effluent disrupts the pituitary-gonad axis of white sucker at multiple sites. Ecotoxicol Appl Pharmacol 1992;115: 224–33. [20] McMaster ME, Van Der Kraak GJ, Munkittrick KR. An epidemiological evaluation of the biochemical basis for steroid hormonal depressions in fish exposed to industrial wastes. J Great Lakes Res 1996;22:153–71. [21] Kaplin C, Holmbom B, Huhtiniemi M. Removal and degradation of wood resin components in an activated 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 Pulp and Paper Mill Effluents, PAPRO, Rotorua, NZ, 2003. p. 146–152, in press. [22] Lappalainen J, Juvonen R, Vaajasaari K, Karp M. A New Flash method for measuring the toxicity of solid and colored samples. Chemosphere 1999;38:1069–83. [23] Tarkpea M, Eklund B, Linde M, Bengtsson B-E. Toxicity of conventional, elemental chlorine-free, and totally chlorine-free kraft-pulp bleaching effluents assessed by short-term lethal and sublethal bioassays. Environ Toxicol Chem 1999;18:2487–96. [24] Ruonala S, Lammi R. Environmental impacts of pulp bleaching based on oxygen chemicals. In: Servos MR, Munkittrick KR, Carey JH, Van Der Kraak G, editors.
[25] [26]
[27]
[28]
Environmental fate and effects of pulp and paper mill effluents. Delray Beach, FL: St. Lucie Press, 1996. Leach JM, Thakore AN. Toxic constituents in mechanical pulping effluents. Tappi 1976;59:129–32. Oconnor BI, Kovacs TG, Voss RH. The effect of wood species composition on the toxicity of simulated mechanical pulping effluents. Environ Toxicol Chem 1992;11: 1259–70. Cates DH, Eggert C, Yang JL, Eriksson K-EL. Comparison of effluents from TCF and ECF bleaching of kraft pulps. Tappi J 1995;78:93–8. Tana J. Puuper.aiset uuteaineet Enocell Oy:n ulosmenev. a. ss.a j.atevedess.a. Suomen Ymp.aristoTutkijaryhm. a Oy, 1993.
Removal of resin acids and sterols from pulp 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 elemental chlorine free bleaching kraft pulp mill located in eastern Finland was sampled in order to study the fate of wood 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. During wastewater 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 After changes in the bleaching processes, research on pulp mill effluents has expanded from chlorinated compounds to wood extractives such as resin acids and sterols [1]. These extractives cause foaming problems and are impurities in the products and on the equipment of pulp and paper mills [2]. Since the early 1990s, the use of ECF bleaching techniques has become common, replacing the use of chlorine gas [3]. Moreover, in the 1980s, the introduction of activated sludge wastewater treatment has reduced BOD in effluents by 85–95% and COD by 40–80% [4]. Other improvements in the process *Corresponding author. Tel.: +358-13-2513575; fax: +35813-2513590. E-mail address: jussi.kukkonen@joensuu.fi (J.V.K. Kukkonen).
have also reduced the load: modified cooking, oxygen delignification, more effective washing of pulp and more closed water circulation [1,3,5]. Secondary treatment of pulp mill effluents reduces, in addition to BOD and COD, the toxicity of effluents [4,6]. Many studies have found resin acids and unsaturated fatty acids toxic to aquatic organisms, and various methods have been used to test toxicity [7–9]. Recently, bacterial testing has become popular because it is sensitive and relatively quick and easy to perform [6,10,11]. Quite recently, it has been shown that plant sterols (phytosterols) may act as disrupters of the hormonal and biochemical systems of aquatic organisms. The structure of phytosterols is similar to that of the steroid hormones of vertebrates. Transformation products of sterols, in particular, can have adverse endocrine effects, androgenic 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
A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820
2814
impacts of pulp mill effluents have been reported, for instance, stimulated growth and enzymatic induction [15–17], and decrease in levels of sex hormones and in reproductive capacity [12,18–20]. Transformation products of sterols and resin acids can be formed during biological treatment of wastewater [13,14,17]. Possible transformation reactions are hydrogenation, hydroxylation, decarboxylation and aromatization. Up to 40% of the discharged compounds can be in the form of transformation products [13]. The objective of this study was to analyze removal of resin acids and plant sterols from effluent of an ECF kraft pulp mill by an activated sludge treatment plant. To get an overview of the performance of the treatment plant, the samples were collected at different points in the treatment process and during different runs of the pulp mill. In addition to chemical analysis, the overall bacterial toxicity of the samples was tested.
2. Materials and methods Wastewater treatment plant of an ECF (O-Do-EOPD-D) kraft pulp mill located in eastern Finland was sampled in order to study the fate of extractives and luminescence bacterial (V. fischeri) toxicity in different parts of the plant (Fig. 1). In 1998, the pulp production in this mill was 586 000 ADt/a; and the discharged loads of COD, AOX, P and N were 7 640, 90, 2, and 39 t/a, respectively. The pulp mill uses ca. 40 m3 water per ton of pulp produced. The samples were taken during three different runs, twice in each. The runs were: (1) both fibrelines producing birch pulp (Birch), (2) one line producing birch pulp and the other producing conifer pulp (Norm), and (3) one line producing birch and the other producing conifer pulp with a higher percentage of spruce (Reinf). Samplings were performed considering
Debarking
Activated sludge treatment
Ecological pond Secondary clarifiers
Primary clarifier
1
the hydraulic retention. Background information on the samplings is presented in Table 1. Before the analyses, the wastewaters were filtered on Whatman GF-C filters. Solids in the water and dry weights of the sludges were determined. Water and particle samples were stored at 20 C until analyzed. In addition, the sludge samples were freeze-dried with a HETOSICC freeze-drier. Filtered water, solid matter with the filter, and freeze-dried sludge samples were extracted according to Kaplin et al. [21]. Briefly, the water samples were extracted with hexane/EtOH (v/v: 4/1) as solvent. The solid matter with filter and the sludge samples were hydrolyzed with 0.5 M KOH in 90% EtOH and were then further extracted with diethyl ether. Derivatized samples were analyzed semiquantitatively with a Hewlett-Packard GC-MSD accompanied with an HP-1 column (25 m, i.d. 0.32 mm, film thickness 0.17 mm). The analyzed compounds are shown in Table 2. Of these compounds, levopimaric acid and palustric acid, as well as 7-prenol and 24-methylene cycloartenol overlapped. The internal standards used were heneicosanoic acid (21:0) and cholesterol. Later in this article, triterpenyl alcohols and squalene are included in the sterol group. Dissolved organic carbon (DOC) was determined from the filtered water samples with a Shimadzu total organic carbon analyzer 5000A (Shimadzu, Kyoto, Japan). In addition, total carbon contents of solid matter and sludges were analyzed with a CHNanalyzer (Carlo Erba Elemental Analyzer, Milano, Italy). Bacterial (V. fischeri) toxicity and the EC50 values of the non-filtered effluents and sludges were determined with a Flash-test [22] by Bio-Nobile Oy, Turku, Finland. The Flash-test is a kinetic directcontact luminescent bacterial test. The test is comparable to other bacterial tests (i.e. Microtox) and it is recommended for colored samples [22] because each
4
3
2
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.
5
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 sampling points Birch/spruce
Production, ADt/d Birch/conifer, ADt/d Average flow, m3/d AOX, kg/d CODCr in, mg/l CODCr out, mg/l BOD7 in, mg/l BOD7 out, mg/l DOC in, mg/l DOC out, mg/l OC in, mg/l OC out, mg/l totP out, mg/l totN out, mg/l pH in pH out Solids 2a, mg/l Solids 3a, mg/l Solids 5a, mg/l Solids 6a, mg/l Solids 7a, mg/l a
Birch/conifer
Reinf1
Reinf2
Norm1
Norm2
Birch1
Birch2
1945 1315/630 71 400 258 1658 364 459 7 282 143 34.9 14.3 0.08 1.37 6.1 8.0 219 81 5.4 7320 5880
1727 1147/580 67 800 230 2080 308 675 7 430 168 38.4 14.6 0.07 1.23 6.0 8.2 244 129 6.8 46 330 5720
1986 1363/623 63 400 240 1602 323 569 6 388 142 44.0 13.9 0.06 1.61 7.6 8.0 265 85 5.0 14 490 4900
1856 1351/505 63 300 240 1964 342 621 7 486 130 44.8 14.9 0.05 0.84 6.2 8.0 267 129 1.2 30 250 3800
1638 1638/0 65 500 230 1492 272 496 6 483 304 42.7 13.6 0.07 2.2 6.5 8.0 590 112 4.0 6950 6870
1978 1978/0 65 800 230 2064 302 599 8 361 123 37.6 14.9 0.04 1.46 6.9 8.0 690 84 4.8 33 850 5440
Number of a sampling point; see Fig. 1.
Table 2 Analyzed compounds Resin acids
Sterols
Triterpenyl alcohols
Hydrocarbon and prenol
Pimaranes Pimaric acid Sandaracopimaric acid Isopimaric acid
Campesterol Campestanol b-sitosterol Stigmastanol
Lupeol Methylbetulinate Betulinol
Squalene 7-prenol
Abietanes Palustric acid Levopimaric acid Dehydroabietic acid Neoabietic acid Abietic acid
Cycloartenol Citrostadienol 24-methylene cycloartenol
sample acts as its own reference, and no correction for color or turbidity is needed. The luminescence output of the samples, after addition of the bacteria, was first monitored for 30 s and then measured again after 30 min contact time. The results were calculated as EC50 values with both 30 s and 30 min contact times. Because 30 s was not adequate for all samples to show toxicity, we report here the EC50 values for 30 min contact time except for one sample set.
3. Results 3.1. Toxicity to Vibrio fisheri Toxicity (calculated as EC50 values) was found mainly in samples taken before the activated sludge treatment (sampling points 1–3, Table 3). The samples after the biotreatment were non-toxic as was the 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 Sampling point (1) (2) (3) (4) (5) (6) (7)
Mill inflow Total effluent Before As treat Secondary clearout Discharge Primary Sludge Biosludge
Reinf1 a
ND ND 4670.4 NTb ND 2.770.2 NT
Reinf2
Norm1
Norm2
Birch1
Birch2
ND 3571.2 2871.2 ND NT 1671.4 NT
ND ND ND NT NT ND NT
3.977.6 1372.2 6.972.7 NT NT 1.5724 NT
ND 1971.4 2571.6 ND ND 3.673.4 NT
4971.3 1671.3 1372.9 NT NT 46716 NT
For Reinf2, the contact time was 30 s. a =inhibition o50%, EC50 value not determined. b =not toxic, inhibition negative.
samples were found during Norms 1 and 2 sampling periods. Even though the inhibition remained under 50% and EC50 values were not calculated for Norm1 samples, the toxic effect was very rapid. In all of the samplings, the primary sludge was the most toxic sample with EC50 values of 1.5–46%. The EC50 values varied between 13% and 35% in the total wastewaters before primary clarification and between 6.9% and 46% in the waters before biological treatment. In inflow water, in four samplings the inhibition with 30 min contact time was between 16% and 30%. Thus, in two samplings inhibition exceeded 50%, and the EC50 values were calculated. These findings suggest that the debarking effluents might be the reason for toxicity of the total effluent at sampling point 2. In general, at each sampling point, the variation between different samplings was large. 3.2. Wood extractives In this study, the decrease in the concentrations of the analyzed compounds during activated sludge treatment 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 concentrations were 0.10–0.89 and 0.15–0.71 g/t, respectively (Table 4). At the discharge point, the resin acid concentration was highest during the Norm1 run and the sterol concentration was highest during the Reinf2 run. Discharge was lowest in Birch1 sampling. Of the total amount of wood extractives discharged, about 80% were adsorbed to solid matter and 20% were dissolved in the water phase. Thus, large amount of solid matter was correlated to the high concentrations of extractives in samples. Both the resin acid and the sterol load coming to the wastewater treatment was highest in the Norm1 run (Table 4). During that sampling, both particles and water contained the most extractives compared to the other samplings. For the resin acids the concentration in
Table 4 Total concentrations of (A) resin acids (B) sterols (g/t pulp) in particles and water in different parts of the wastewater treatment plant Sampling point Reinf1 Reinf2 Norm1 Norm2 Birch1 (A) Resin acids 1 46 129 2 51 130 3 16 58 4 0.17 0.27 5 0.19 0.19 6 2.3 30 7 20 43 (B) Sterols 1 2 3 4 5 6 7 a
289 60 375 173 162 34 0.70 0.20 0.89 0.17 47 85 838 46
Birch2
44 178 93 276 41a 110 0.02a 0.22 0.10 0.15 0.54 72 28 60
36 112 190 58 102 108 49 137 172 82 123 171 86 62 91 59 85a 86 1.1 1.6 1.2 0.99 0.12a 1.0 0.19 0.19 0.71 0.17 0.44 0.15 10 76 67 177 2.5 217 657 1017 1259 851 1083 1345
=concentration in water only.
the inflow was lowest in the Birch1 run and for the sterols in the Reinf1 run. Before biotreatment, compared to the situation in the discharged water, the amount of extractives in water was higher than in the particles. In the sludges, the resin acid concentrations in the primary sludge were 0.1–4.9 mg/g sludge, and in the biosludge 0.1–5.3 mg/g. The sterol concentrations of the sludge were 1.4–8.9 and 4.4–8.9 mg/g, respectively. Overflow of the sludge thickener increased the concentrations of resin acids and sterols in the sludges. In primary sludge, the daily removal of resin acids was 0.5–85 g/t and that of sterols 2.5–217 g/t. Correspondingly, removal from the biosludge to the sludge thickener was 0.9–35 and 27– 52 g/t, respectively. The most abundant pimarane was isopimaric acid, and the most abundant abietanes 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 (sampling points 1–5; see Fig. 1) during different samplings.
abietic acid. Of the total resin acids, abietanes covered 90% in the water and 94% in the particles before, and 81% and 96%, respectively, after biotreatment. In both sludges, the proportion of abietanes was 96%. The most abundant sterols were b-sitosterol and citrostadienol, and the dominant triterpenyl alcohol was betulinol. Of the sterol group, triterpenyl alcohols covered, on average, 26% in water and 60% in particles before, and 9% and 48%, respectively, after the biotreatment. In sludges, the proportion was 66%. Betulinol, which originates from birch bark, was not present in high concentrations during the Birch runs as had been expected. Before the biotreatment, squalene made up
o1% of the total sterols both in water and in particles, and after biotreatment increased to 9% and 2%, respectively. In addition, in the sludges the corresponding proportion was also o1% of the total sterols. After primary clarification, over 40% of the resin acids and over 36% of the sterols went further to the biotreatment. In the activated sludge treatment, the amount of degraded or transformed resin acids exceeded 94% in all samplings except in Norm1, where it was 78% (Table 5). In that sampling, the amount removed to biosludge was 22%, while in the other samplings it was 2.3–5.6%. The sterol group varied more than the resin acids did. Of the sterols, 41–67% were degraded or
A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820
2818
Table 5 Fate of (A) resin acids and (B) sterols in activated sludge treatment plant; degradation or transformation (degr/transf), removal with sludge and amount going forward to the ecological pool (forward) (%) Degr/transf
Removal
Forward
(A) Resin acids Reinf1 94 Reinf2 96 Norm1 78 Norm2 94 Birch1 97 Birch2 98
5.4 3.1 22 5.6 2.9 2.3
1.1 0.5 0.4 0.6 0.2 0.2
(B) Sterols Reinf1 Reinf2 Norm1 Norm2 Birch1 Birch2
31 43 57 39 53 36
1.3 3.7 1.4 1.8 0.5 0.9
67 53 41 59 47 63
transformed and 31–57% were removed with the sludge to the thickener. In the ecological pool, no more extractives were removed.
4. Discussion 4.1. Toxicity to Vibrio fisheri In previously reported bacterial toxicity tests, at the same mill as studied here with ECF or TCF bleaching and hardwood or softwood, the EC50 values found for untreated effluents were 15–45% [5]. In addition, in another Finnish mill with ECF bleaching and both hardwood and softwood, the EC50 values for untreated effluents were 2–15% [10]. In Sweden, for an ECF mill using softwood the reported EC50 value was 31% [23]. The previous findings are in accordance with the results of our study. It has been elicited that effluent toxicity, and especially the toxicity of resin acids, is dependent on pH [6,9]. In this study, however, the pH of the inflow sample was 6.0–6.9 for all samplings except for Norm1 for which the pH was 7.6. Thus, the toxicity of the Norm2 sample from the inflow cannot be explained by the pH, which was 6.2. Debarking effluents have been reported to be toxic to bacteria [11], which might be the reason for the toxicity of the total effluent (sampling point 2) in this study. Stuthridge and Tavendale [13] found that 60–90% of the effluent toxicity originates from resin acids. It has also been reported that the species of wood can affect effluent toxicity [24–26]. Softwood has been found to be more toxic than hardwood to fish [24] and to P. phosphoreum [27]. No such effect can be found in the results of this study
because of the mixing of wood species. Moreover, for the Norm2 samples, neither the CODCr and BOD7 values nor the concentrations of wood extractives were correlated with toxicity. 4.2. Wood extractives The activated sludge plant removes significant amounts of wood extractives from the pulp mill effluent [7,9,21]. In this study, the reductions were similar to those found in an earlier study [21]. However, the discharged concentrations were lower than in those reported in the beginning of the 1990s [5,28]. Although the total concentrations of resin acids were lower than the concentrations that are acutely toxic to fish, the highest concentrations measured were on a level that can cause physiological effects in fish. For example, 20 mg/l dehydroabietic acid (DHAA) has been reported to have subchronic effects on fish [8]. The LC50 values (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] reported that 10 mg/l exposure to phytosterols, accumulated via the mother, already has an effect on fish larvae, stimulating their growth. During exposure to treated effluent, juvenile rainbow trouts also grew more [17]. In addition to the effect on growth, disturbance of endocrine mechanisms affects both metabolism and reproduction [20]. Decreased reproductive capacity is mainly due to the lower level of sex steroids in the parent fish and the effect of sterols on vitellogenesis [15]. It should be noted, however, that at the discharge point the effluent is diluted considerably. Even though over 90% of the resin acids analyzed here are removed in biotreatment, the residue discharged can still be toxic to aquatic organisms [9]. Of the reduced 90%, 40% may consist of biotransformed forms of resin acids, such as decarboxylated resin acid hydrocarbons, partially or fully saturated resin acids and oxygenated resin acids [13]. Studies on sterols have shown that they are more likely to be biotransformed by bacteria than to degrade [1,17]. Moreover, the transformation products can cause the effects mentioned above. The different samplings were not directly comparable. Both the concentrations and the production were highest during the Norm1 sampling (Tables 1 and 4). The high concentrations were mainly due to 1-day shutdown of the mill. The overflow of the sludge thickener influenced the amount of water solids (Table 1) and the concentrations of extractives at sampling points no. 2, 3, and 6 (Table 4) during samplings Norm1 and 2, Birch2, and Reinf2, but did not affect the efficiency of the activated sludge treatment plant, nor did the 1-day shutdown. This was due to efficient adsorption of wood extractives onto the biosludge (Table 5). However, the concentrations of CODCr or BOD7 were effected only by
A. Kostamo, J.V.K. Kukkonen / Water Research 37 (2003) 2813–2820
overflow of the sludge thickener, not the shutdown of the mill (Table 1).
5. Conclusions Both the performance and the operation stability of the activated sludge treatment plant were good. Even though the different sample series were not fully comparable, the disturbing factors that increased the load of wood extractives did not affect the operation efficiency of the secondary treatment system. However, the concentrations of wood extractives in the discharged water were still at a level that can have subchronic effects on organisms living in the water. Most of the extractives were discharged attached to particles. Thus, a main conclusion of this work is that, by improving the removal of fine particles, the removal of wood extractives can be even further improved.
Acknowledgements This study was financed by the National Technology Agency (TEKES), Stora-Enso Oyj and Aquaflow Oy. We acknowledge Eeva Punta and Petri Lassila ( (Enocell Oy), Eija Bergelin and Camilla Kaplin (Abo Akademi) for their co-operation and Prof. Bjarne ( Holmbom (Abo Akademi) for valuable discussions and comments during the project. We also acknowledge, Risto Juvonen (Bio-Nobile Oy) for comments on the toxicity tests.
References [1] Tana J, Lehtinen K-J. Valkaistun massan tuotannosta . aiheutuvien j.atevesien ymp.aristovaikutusten arviointi . yleiskatsaus. Suomen ymp.aristokeskus, 1996. [2] Ekman R, Holmbom B. Analysis by gas chromatography of the wood extractives in pulp and water samples from mechanical pulping of spruce. Nord Pulp Pap Res J 1989; 4:16–24. . [3] Axeg(ard P, Dahlman O, Hagling I, Jacobson B, Morck R, . Stromberg L. Pulp bleaching and the environment— the situation in 1993. Nord Pulp Pap Res J 1993;8: 365–78. [4] Saunam.aki R. Biological waste water treatment in the Finnish pulp and paper industry. Pap Timber 1989;2: 158–64. [5] Punta E, Suppola J. Toxicity reduction of a modern Finnish bleached kraft pulp mill by effluent treatment plant. Atlanta: TAPPI Environmental, 1995. [6] Kovacs TG, Voss RH. Biological and chemical characterization of newsprint/specialty mill effluents. Water Res 1992;26:771–80.
2819
[7] Easty DB, Borchardt LG, Wabers BA. Wood derived toxic compounds: removal from mill effluents by waste treatment processes. Tappi 1978;61:57–60. . [8] Oikari A, Lonn B-E, Castr!en M, Nakari T, SnickarsNikinmaa B, Bister H, Virtanen E. Toxicological effects of dehydroabietic acid (DHAA) on the trout, Salmo gairdneri Richardson, in fresh water. Water Res 1983;17: 81–9. [9] Werker AG, Hall ER. The influence of pH on the growthlinked biodegradation kinetics of selected resin acids found in pulp mill effluent. TAPPI J 1999;82:169–77. [10] Verta M, Ahtiainen J, Nakart T, Langi A, Talka E. The effect of waste constituents on the toxicity of TCF and ECF pulp bleaching effluents. In: Servos MR, Munkittrick KR, Carey JH, Van Der Kraak G, editors. Environmental fate and effects of pulp and paper mill effluents. Delray Beach, FL: St. Lucie Press, 1996. [11] Ahtiainen J, Ruoppa M, Nakari T, Verta M. Toxicity screening of novel pulping influents and effluents in Finnish pulp mills. In: Servos MR, Munkittrick KR, 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 issue. TAPPI Environmental, Canada, 1995. [13] Stuthridge TR, Tavendale MH. Biotransformation and partitioning of resin acids within an aerated stabilization basin. TAPPI Proceedings, 1995. . [14] Stahlschmidt-Allner P, Allner B, Rombke J, Knacker T. Endocrine distrupters in the aquatic environment. Environ Sci Pollut Res 1997;4:155–62. . C, Lerche O, [15] Lehtinen K-J, Mattson K, Tana J, Engstrom Hemming J. Effects of wood-related sterols on the reproduction, egg survival, and offspring of brown trout (Salmo trutta lacustris L.). Ecotoxicol Environ Saf 1999; 42:40–9. [16] Mattson K, Lehtinen K-J, Tana J, H.arding J, Kukkonen J, . C. Effects of pulp mill effluents and Nakari T, Engstrom restricted diet on growth and physiology of rainbow trout (Oncorhynchus mykiss). Ecotoxicol Environ Saf 2001;49: 144–54. . C, Hemming J, Lehtinen K[17] Mattson K, Tana J, Engstrom J. Effects of wood-related sterols on the offspring of the viviparous blenny, Zoarces viviparus L. Ecotoxicol Environ Saf 2001;49:122–30. [18] Tremblay L, Van Der Kraak G. Comparison between the effects of the phytosterol b-sitosterol and pulp and paper mill effluents on sexually immature rainbow trout. Environ Toxicol Chem 1999;18:329–36. [19] Van Der Kraak GJ, Munkittrick KR, McMaster ME, Portt CB, Chang JP. Exposure to bleached kraft pulp mill effluent disrupts the pituitary-gonad axis of white sucker at multiple sites. Ecotoxicol Appl Pharmacol 1992;115: 224–33. [20] McMaster ME, Van Der Kraak GJ, Munkittrick KR. An epidemiological evaluation of the biochemical basis for steroid hormonal depressions in fish exposed to industrial wastes. J Great Lakes Res 1996;22:153–71. [21] Kaplin C, Holmbom B, Huhtiniemi M. Removal and degradation of wood resin components in an activated 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 Pulp and Paper Mill Effluents, PAPRO, Rotorua, NZ, 2003. p. 146–152, in press. [22] Lappalainen J, Juvonen R, Vaajasaari K, Karp M. A New Flash method for measuring the toxicity of solid and colored samples. Chemosphere 1999;38:1069–83. [23] Tarkpea M, Eklund B, Linde M, Bengtsson B-E. Toxicity of conventional, elemental chlorine-free, and totally chlorine-free kraft-pulp bleaching effluents assessed by short-term lethal and sublethal bioassays. Environ Toxicol Chem 1999;18:2487–96. [24] Ruonala S, Lammi R. Environmental impacts of pulp bleaching based on oxygen chemicals. In: Servos MR, Munkittrick KR, Carey JH, Van Der Kraak G, editors.
[25] [26]
[27]
[28]
Environmental fate and effects of pulp and paper mill effluents. Delray Beach, FL: St. Lucie Press, 1996. Leach JM, Thakore AN. Toxic constituents in mechanical pulping effluents. Tappi 1976;59:129–32. Oconnor BI, Kovacs TG, Voss RH. The effect of wood species composition on the toxicity of simulated mechanical pulping effluents. Environ Toxicol Chem 1992;11: 1259–70. Cates DH, Eggert C, Yang JL, Eriksson K-EL. Comparison of effluents from TCF and ECF bleaching of kraft pulps. Tappi J 1995;78:93–8. Tana J. Puuper.aiset uuteaineet Enocell Oy:n ulosmenev. a. ss.a j.atevedess.a. Suomen Ymp.aristoTutkijaryhm. a Oy, 1993.