Removal of Resin and Fatty Acids from Pulp Mill Wastewater Streams

REMOVAL OF RESIN AND FATTY ACIDS FROM PULP MILL WASTEWATER STREAMS

A Dissertation Presented to The Academic Faculty

Stephen P. Makris

In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Chemical and Biomolecular Engineering School

Georgia Institute of Technology September, 2003

Removal of Resin and Fatty Acids from Pulp Mill Wastewater Streams

Approved by:

Dr. Sujit Banerjee, Advisor

Dr. Yulin Deng

Dr. Howard L. Empie

Dr. Lucian A. Lucia

Dr. Spyros G. Pavlostathis

Approved January 5, 2004 ACKNOWLEDGEMENTS

Pursuing a Ph.D. degree is both a journey and a commitment requiring the support of many people. I have been extremely fortunate to be surrounded by many talented and caring mentors, colleagues, friends and family. I would like to recognize the assistance of some of these people here.

First, I would like to acknowledge the support of the member companies of the

Institute of Paper Science and Technology for partially funding this research and my education. My thanks are also extended to Georgia-Pacific Corporation for additional funding and assistance from Keith Bentley, Robert Sackellares, Myra Carpenter, Carl

Rush, and Tobin Finley. I would also like to thank Greg Hollod and Dell Majure at

Riverwood International for their support of this research.

I gratefully thank my advisor, Sujit Banerjee, for the guidance, inspiration and the moments of levity that helped to keep me on course and focused on the completion of this dissertation. I would also like to thank my dissertation committee, Yulin Deng,

Howard L. “Jeff” Empie, Lucian A. Lucia, and Spyros G. Pavlostathis, for their time reviewing this manuscript and their thoughtful advice.

I give special thanks to my friends and family for their unwavering support; I truly could not have completed this journey without them. My greatest thanks go to my wife, best friend, and light of my life. Libby, this dissertation is dedicated to you.

iii TABLE OF CONTENTS

Acknowledgement ...... iii

Table of contents...... iv

List of Tables ...... vii

List of Figures...... ix

List of Symbols and Abbreviations...... xi

Summary...... xii

1. Background...... 1

1.1. Toxicity Definitions and Testing ...... 2

1.2. Toxicity of Effluent Components ...... 7

Bleach Plant Byproducts...... 7

Natural Components ...... 9

1.3. Effluent treatment systems...... 13

1.4. Sources of Toxic Components...... 16

1.5. Partitioning of Resin Acids...... 18

1.6. Section Summary...... 24

2. Dissertation Questions and Research Objectives...... 27

2.1. Research Objectives...... 28

2.2. Thesis Approach ...... 30

3. RFA and Toxicity Removal Across the ETS...... 32

3.1. Section Overview...... 32

3.2. Experimental Approach ...... 33

3.3. Experimental...... 35

3.4 Results and Discussion ...... 44

3.5. Section Summary...... 69

4. DHA Acute and Chronic Toxicity in Treatment System Effluents...... 71

4.1. Section Overview...... 71

4.2. Experimental Approach ...... 73

4.3. Experimental...... 74

Microtox® bioassays ...... 74

Ceriodaphnia dubia bioassays...... 76

4.4. Results and Discussion ...... 78

Microtox® dose-response experiments ...... 78

C. dubia dose-response experiments...... 81

4.5. Section Summary...... 85

5. Mapping Pulp Mill Sewers for Resin and Fatty Acids ...... 86

5.1. Section Overview...... 86

5.2. Experimental Approach ...... 87

5.3. Experimental...... 93

5.4. Results and Discussion ...... 95

5.5. Section Summary...... 100

6. Resin and Fatty Acids Removal from Pulp Mill Sewers using Flotation...... 102

6.1. Section Overview...... 102

6.2. Experimental Approach ...... 103

6.3. Experimental...... 109

6.4. Results and Discussion ...... 113

6.5. Section Summary...... 124

7. Conclusions and Recommendations ...... 125

Appendix A.1...... 134

Appendix A.2...... 140

References...... 146

vi LIST OF TABLES

Table 1.1. Fatty acids most commonly found in wastewater streams...... 11

Table 1.2: LC50 (Rainbow trout) of key extractives...... 13

Table 3.1. Mill A effluent treatment system characteristics...... 36

Table 3.2. Summary of sample collection dates and testing matrix...... 43

Table 3.3. Operational ranges for Mill A ETS influent...... 45

Table 3.4. Operational ranges for Mill A ETS final effluent...... 45

Table 3.5. Overall ETS operating efficiencies and flow rates at Mill A...... 46

Table 3.6. Statistical significance of COD levels across ETS (α = 0.05)...... 48

Table 3.7. Acute and chronic toxicity for December 6-10, 1999...... 49

Table 3.8. Acute and chronic toxicity for March 6-9, 2000...... 49

Table 3.9 Average RFA and TSS concentration during effluent treatment...... 52

Table 3.10 Average RFA and TSS removal contributions to overall removal rate...... 54

Table 3.11. Physicochemical properties for model resin and fatty acids,...... 59

Table 3.12. Comparison of DHA and RFA levels (ppm) across Mills A and B...... 68

Table 4.1. Volumetric concentrations used in Microtox® dose-response experiments. ... 75

Table 4.2. Test conditions for DHA chronic toxicity dose-response experiments...... 77

Table 4.3. Results of the Microtox® dose-response experiments...... 79

Table 4.4. Sample pH range over duration of chronic dose-response experiments...... 82

Table 5.1 – Separation processes and operating principles...... 88

Table 5.2 – Physicochemical properties of DHA...... 89

Table 5.3 - RFA concentration, flow rate, temperature and pH of Mill A sewers...... 95

Table 5.4 – RFA concentration, flow rate, temperature and pH of Mill B sewers...... 96

Table 5.5 – RFA sewer concentration, flow and treatment system loading in Mill C...... 97

Table 6.1. RFA concentration, flow rate, temperature and pH of sewer samples...... 114

vii Table 6.2. Determination of particle removal rate coefficient, KE...... 118

Table A.1a. Summary of toxicity test conditions for the water flea, C. dubia, survival and reproduction for Mill A...... 134

Table A.1b. Initital chemical characterization of final effluent and controls used in chronic toxicity testing for Mill A...... 135

Table A.1c. Initital chemical characterization of final effluent and controls with DHA spike used in chronic toxicity testing for Mill A...... 135

Table A.1d. Daily survival and reproduction data for C. dubia chronic test of final effluent for Mill A...... 136

Table A.1e. Daily survival and reproduction data for C. dubia chronic test of final effluent with DHA spike for Mill A...... 138

Table A.2a. Summary of toxicity test conditions for the water flea, C. dubia, survival and reproduction for Mill C...... 140

Table A.2b. Initital chemical characterization of final effluent and controls used in chronic toxicity testing for Mill C...... 141

Table A.2c. Initital chemical characterization of final effluent and controls with DHA spike used in chronic toxicity testing for Mill C...... 141

Table A.2d. Daily survival and reproduction data for C. dubia chronic test of final effluent for Mill C...... 142

Table A.2e. Daily survival and reproduction data for C. dubia chronic test of final effluent with DHA spike for Mill C...... 144

viii LIST OF FIGURES

Figure 1.1 Chemical structures of natural extractive wood components...... 10

Figure 1.2. Summary of Ceriodaphnia dubia reproduction test in Canada...... 15

Figure 3.1. Secondary treatment system before (top) and after (bottom) changes in aeration...... 37

Figure 3.2. ASB sampling locations for Mill B...... 38

Figure 3.3. Chemical oxygen demand profiles for samples collected from May 1999 through March 2000...... 47

Figure 3.4: COD and toxicity profiles across secondary treatment...... 50

Figure 3.5. Average fatty and resin acid profiles across effluent treatment system...... 53

Figure 3.6. Total suspend solids (triangles), unfiltered (solid diamond) and filtered (open) resin acid concentrations...... 55

Figure 3.7: Relationship between bound RFA and TSS...... 56

Figure 3.8. Total unfiltered RFA (solid) and DHA (open) profiles collected at various periods...... 61

Figure 3.9. Acute and chronic toxicity profiles and unfiltered (solid) and filtered (open) DHA concentration profiles for December 1999 (left). and March 2000 (right)...... 62

Figure 3.10. Unfiltered Dehydroabietic acid profiles for samples collected from May 1999 through March 2000...... 63

Figure 3.11. Relationship between total filtered resin and fatty acids and toxicity index.65

Figure 3.12: COD, RFA, and DHA profiles for samples collected in December 1999 (left) and March 2000 (right)...... 66

Figure 4.1. Dose-response curve for DHA spike in final effluent using Microtox® WETprotocol...... 79

Figure 4.2. Correlation between DHA concentration and Microtox® acute toxic effect. . 81

Figure 4.3. Effect of final effluent unmodified and amended with DHA on number of C. dubia neonates reproduced...... 84

Figure 5.1 – Chemical structure of DHA...... 88

Figure 5.2 – Particle size ranges for various separation processes...... 92

ix Figure 5.3 – Mill A wastewater sewer system...... 94

Figure 5.4 – Suspended solids distribution for the pulp mill decker filtrate samples...... 99

Figure 5.5 Particle size distribution for the pre-bleach washer press filtrate...... 99

Figure 6.1. Schematic of experimental flotation column...... 110

Figure 6.2. Images used for bubble-size image analysis...... 112

Figure 6.3. Gas holdup as a function of superficial gas velocity...... 115

Figure 6.4. Bubble size distribution (Sauter mean diameter = 1.4 mm)...... 116

Figure 6.5. Fractional removal of RFA with TSS...... 117

Figure 6.6. Removal of TSS from decker filtrate with time and airflow rate...... 119

Figure 6.7. Removal of RFA from decker filtrate with time and airflow rate...... 121

Figure 6.8. Removal of RFA from pre-bleach washer press with time and air flow rate...... 122

LIST OF SYMBOLS AND ABBREVIATIONS

AOX: Adsorbable organic halides ASB: Aerobic stabilized basin AST: Activated sludge treatment BOD: Biochemical oxygen demand [=] mass/ L3 3 C1: Solids concentrations in the liquid phase [=] mass/ L 3 C10: Solids concentration in liquid at time 0 [=] mass/L 3 C1f: Solids concentration in liquid at time f [=] mass/L COD: Chemical oxygen demand [=] mass/ L3 dbs: Sauter mean bubble diameter (volume to surface ratio) [=] L DHA: Dehydroabietic acid db: Bubble diameter [=] L dp: Particle diameter [=] L DO: Dissolved oxygen [=] mass/ L3 EC50: Concentration exhibiting a 50% effective endpoint [=] % Eg Gas holdup (volume percentage of gas in liquid) [=] unitless EL: Embryo-larval EST: Effluent treatment system IC25: Concentration exhibiting a 25% inhibitory effect on the test population [=] % Kd: Fiber:water partitioning coefficient [=] unitless KE: Fine suspended particle removal coefficient [=] Length/time o Kl : Lignin:water partitioning coefficient [=] unitless Kow: Octanol:water partitioning coefficient [=] unitless LC50: Concentration exhibiting a lethal effect on 50% of the test population [=] % LOEC: Lowest observable effect concentration [=] % MFO: Mixed function oxygenase MGD: Million gallons per day NOEC: No observable effect concentration [=] % P: Liquid phase dispersion coefficient [=] L3/time pKa: Acid dissociation constant 3 R1: Solids removal rate [=] mass/L rb: Bubble radius [=] Length rp: Suspended solid particle radius [=] L RFA: Resin and fatty acids tf: time f, at the end of the experiment TI: Toxicity index [=] unitless TSS: Total suspended solids [=] mass/L3 ug: Superficial gas velocity [=] L/time u1: Superficial liquid velocity [=] L/time U∞ Terminal bubble velocity [=] Length/time WET: Microtox® whole effluent toxicity protocol z: Column length [=] L α: Fraction of acid dissociated η: Kappa number

SUMMARY

Resin and fatty acids (RFA) are predominantly components of coniferous trees

having the natural function of protecting against microbial damage. These compounds are

released from wood during the pulping process and a fraction reaches the wastewater

treatment system. RFA are acutely toxic to aquatic organisms at concentrations on the

order of parts per million, and their presence has been linked to toxicity outbreaks in

receiving waters following process upsets. The chronic toxicity of resin and fatty acids in

complex effluent matrices is poorly understood. Furthermore, the role of hydrophobic,

pulp-derived solids as a removal pathway from wastewater streams has not been

comprehensively studied. The objectives of this dissertation have been to quantify the

relationship between resin and fatty acid concentration and chronic toxicity and to

determine the role of partitioning in the removal of these compounds from pulp mill

wastewater streams. Field and laboratory studies were conducted to measure toxicity using the Microtox® whole effluent toxicity and Ceriodaphnia dubia 7-day, survival and

reproduction bioassays. One resin acid in particular, dehydroabietic acid, was found to

account for a significant fraction of final effluent chronic toxicity. Dissolved and sorbed

RFA concentrations were quantified by solvent extraction, methyl ester derivatization,

and GC-FID analysis. Partitioning to suspended solids was found to be a major removal

pathway for the RFA from the effluent treatment system. A kinetic model for flotation

was applied and compared to experimental data. Flotation was found to be effective at

selectively removing RFA bound to pulp-derived solids from pulp mill and bleach plant

sewers at moderate to high pH.

xii

1. Background

In 1994, the American Forest & Paper Association (AF&PA) and Department of

Energy (DOE) identified research needs for the U.S. forest products industry in Agenda

2020: A Technology Vision and Research Agenda for America's Forest, Wood, and Paper

Industry. The compact identified five key drivers impacting the future sustainability of the industry. One of these drivers was developing the capability to meet “demanding environmental requirements without the predicted increases in capital expenditures, operating costs and energy consumption1. In 1997, the National Council for Air and

Stream Improvement (NCASI) issued an RFP on behalf of the Agenda 2020

Environmental Performance Task Group soliciting outstanding research needs. The top area included the impact and control of organic compounds expected to accumulate with increased mill closure2. In 1999, AF&PA issued a forest products technology roadmap to help industry, government and universities identify opportunities to make relevant and meaningful contributions toward common research goals. Their Environmental Task

Force established three strategic pathways3 for achieving research goals related to:

• Improving margins of environmental safety through understanding impacts;

• Developing process alternatives consistent with pollution prevention,

such as in-mill improvements; and

1 “Agenda 2020 The Path Forward: An Implementation Plan” American Forest & Paper Association, Washington, D.C. (1999). 2 "NCASI Distributes RFP for Environmental Research Under Agenda 2020" NCASI Bulletin Board, 23(11), (1997). 3 The pathways for the focus areas of impacts, process and treatment are detailed in NCASI Bulletin Board, 23(11). 1

• Advancing treatment areas, including treatment system improvements,

new treatment options, and waste utilization.

The impact and control of organics was listed as one of the top environmental performance priority areas of interest in the environmental roadmap.

As pulp and paper mills continue to reduce fresh water consumption and recycle processed waters, the concentration of contaminants in the purged effluents will increase.

Specifically, effluent toxicity will increase with progressive mill closure due to this concentration. However, the identity of compounds contributing to residual effluent toxicity is not quantitatively known. These compounds may be especially recalcitrant to the effluent treatment system. Therefore, priority should be placed on research with the objectives of identifying and removing contaminants contributing to this toxicity at their source.

1.1. Toxicity Definitions and Testing

Toxicity is a substance's ability to cause harm to living organisms due to detrimental effects on tissues, organs, or biological processes4. However, whether a substance is toxic or not depends on the type of organism exposed, the quantity of substance and the route of exposure. The quantity depends on dose and toxicant concentration, while exposure depends on duration, frequency and rate. Differences in

4 Manahan, S.E. Toxicological Chemistry Chapter, in Environmental Chemistry, Sixth Edition, Lewis Publishers, Boca Raton, FL, (1994), pp. 649-655. 2

these variables among test methods can lead to very different responses to the same compounds. Thus, choosing one toxicity test is not sufficient to characterize the potential of an effluent to cause harm.

The types of toxicity tests can be broadly divided into acute and chronic tests. The response of an acute toxicity test is mortality, typically measured as the median lethal concentration (LC50), i.e. the concentration resulting in 50% mortality of the test specimens5. Chronic toxicity tests cover a wider range of responses, including rates of survival, reproduction, respiration, growth and cell division, light reduction in certain bacteria, mixed-function oxygenase (MFO) induction and mutagenic potential6,7,8,9,10.

Common toxicity tests used for pulp mill effluent characterization range from quantifying sample concentrations that elicit a lethal response to a population of organisms, to minimum concentrations impairing biological functions such as reproduction, weight, growth, and enzyme induction11,12. The EPA has standard acute

5 Rand, G.M. and Petrocelli, S.R. Fundamentals of Aquatic Toxicology - Methods and Applications, Hemisphere Publishing Corporation, Washington, D.C. (1985) 6 Rand, G.M. and Petrocelli, S.R. Fundamentals of Aquatic Toxicology - Methods and Applications, Hemisphere Publishing Corporation, Washington, D.C. (1985) 7 Ard, T.A. and McDonough T.J. "Toxicity Assays in the Pulp and Paper Industry- A Review and Analysis," IPST Technical Paper Series 608, Atlanta, GA, (1996). 8 Horning II, W.B. and Weber, C.I. "Fathead Minnow (Pimephales promelas) Embryo Larval Survival and Teratogenicity Test" Method 1001.0, in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 42-57. 9 Horning II, W.B. and Weber, C.I. "Ceriodaphnia Survival and Reproduction Test" Method 1002.0 in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 58-75. 10 Lehtinen, K. "Biochemical Responses in Organisms Exposed to Effluents from Pulp Production: Are They Related to Bleaching?" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 359-368. 11 Ard, T.A. and McDonough T.J. "Toxicity Assays in the Pulp and Paper Industry- A Review and Analysis," IPST Technical Paper Series 608, Atlanta, GA, (1996). 3

toxicity test methods for both freshwater and estuarine/marine organisms13. The freshwater organisms include daphnids, fathead minnow, and trout, and marine organisms include minnows and silversides. The Ceriodaphnia, fathead minnow and

algal growth tests also have variations that are standard EPA methods for measuring

chronic toxicity14,15.

The Ceriodaphnia dubia survival and reproduction test16 is one of the most common tests for chronic responses. It is a seven-day static renewal test; i.e. the organisms are exposed to a fresh solution daily. This test is considered a life cycle assay, as three broods of young are typically produced during the seven-day period. Toxicity is reported as lowest observed concentration exhibiting an adverse effect (LOEC) and no observed adverse effect (NOEC), for both survival and reproduction. Advantages include completion of life cycle, duration, and it is an EPA standard method. Disadvantages of the test include poor reproducibility of the results and storage effects on effluent samples.

The fathead minnow embryo-larval (EL) survival and teratogenicity test is sometimes termed a subchronic toxicity test. This is because EL toxicity tests are not life

12 Cook, D.; Parrish, A.; Borton, D.; and Hall, T. "A Summary of Pulp and Paper Mill Experiences with Toxicity Reduction and Toxicity Identification Evaluations (TRE/TIE)" in 1998 International Environmental Conference & Exhibit Proceedings, Tappi Press, Atlanta, GA, (1998), pp. 1081-1094. 13 Weber, C.I. Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-90-027, (1991). 14 Horning II, W.B. and Weber, C.I. "Fathead Minnow (Pimephales promelas) Embryo Larval Survival and Teratogenicity Test" Method 1001.0, in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 42-57. 15 Horning II, W.B. and Weber, C.I. "Ceriodaphnia Survival and Reproduction Test" Method 1002.0 in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 58-75. 16 Horning II, W.B. and Weber, C.I. "Ceriodaphnia Survival and Reproduction Test" Method 1002.0 in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 58-75. 4

cycle tests; they assay the early developmental stages. However, as these stages are more sensitive than later stages, EL tests can still estimate "no-effect" concentrations17. In the eight-day static renewal test, embryos and larvae are exposed to different concentrations of effluent. Percent survival, larval growth (dry body weight) and gross morphological deformities are measured, and LOEC, NOEC and the threshold concentration are reported18. The advantages include short test duration, less expense than chronic (life cycle) studies, a higher-order organism (than Ceriodaphnia), accuracy, reproducibility and this is an EPA standard method. One concern with EL tests has been the lack of standardized methods, though this is being addressed19.

Rainbow trout acute and chronic toxicity tests have been used extensively in characterizing the effect of pulp mill effluents on aquatic life20,21. Chronic tests can be done by various methods, varying in duration from days to years. Enzyme induction assays encompass days to weeks and results are reported as potential to induce MFO.

When an organism is exposed to a toxicant, enzymes are produced in the liver to detoxify the compound by hydroxylation. This response is measured and used as an indication of

17 Dave, G. "Replicability, Repeatability and Reproducibility of Embryo-Larval Toxicity Tests with Fish" in Progress in Standardization of Aquatic Toxicity Tests, A.M.V.M. Soares and P. Calow (ed.), Lewis Publishers, Boca Raton, FL, (1993), pp. 129-157. 18 Horning II, W.B. and Weber, C.I. "Fathead Minnow (Pimephales promelas) Embryo Larval Survival and Teratogenicity Test" Method 1001.0, in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 42-57. 19 Dave, G. "Replicability, Repeatability and Reproducibility of Embryo-Larval Toxicity Tests with Fish" in Progress in Standardization of Aquatic Toxicity Tests, A.M.V.M. Soares and P. Calow (ed.), Lewis Publishers, Boca Raton, FL, (1993), pp. 129-157. 20 Kennedy, C.J.; Sweeting, R.M.; Johansen, J.A; Farrell, A.P.; and McKeown, B.A. "Lethal and Sublethal Effects of Chlorinated Resin Acids and Chloroguaiacols in Rainbow Trout" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 391-400. 21 Hewitt, L.M.; Carey, J.H.; Dixon, D.G.; and Munkittrick, K.R. "Examination of Bleached Kraft Mill Effluent Fractions for Potential Inducers of Mixed Function Oxygenase Activity in Rainbow Trout" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 79-94. 5

potential toxicity. However, poor reproducibility is a serious problem with this method,

as well as poor correlation with acute toxicity tests.

The Microtox® assay is a chronic toxicity test based on the bacterium Vibrio fisheri lux or Photobacterium phosphoreum22. However, the test has been correlated to both the 96-hr LC50 acute toxicity of rainbow trout (r = 0.91) as well as the C. dubia 7- day chronic test (r = 0.94)23. The metabolic reactions of this bacterium naturally result in

visible light emission. Toxicants inhibit this process and the light reduction is measured

and reported as the effective concentration (EC50) resulting in a 50% decrease in luminescence. This test is relatively inexpensive, highly reproducible and comparatively

simple to use. Drawbacks include lower life form and reported correlations with other

tests have been contradictory.

Economic constraints do not allow for multiple toxicity testing, however, it is

apparent that a single test cannot adequately characterize effluent toxicity. Based on

these considerations and the high correlation observed between Microtox® and other key methods, the relatively inexpensive Microtox® acute test and the widely used

Ceriodaphnia dubia chronic test are expected to provide a good combination for quantifying toxicity.

22 Ard, T.A. and McDonough T.J. "Toxicity Assays in the Pulp and Paper Industry- A Review and Analysis," IPST Technical Paper Series 608, Atlanta, GA, (1996). 23 Firth, B.K. and Backman, C.J. (1990) Comparison of Microtox testing with rainbow trout (acute) and Ceriodaphnia (chronic) bioassays in mill wastewaters. Tappi J., 73(12), 169-174. 6

1.2. Toxicity of Effluent Components

In addition to quantifying toxicity, the identity and source of compounds contributing to toxicity are equally important. The following sections summarize research on the toxicity of the component streams that make up the effluent, including bleach plant byproducts and natural compounds.

Bleach Plant Byproducts

Bleach plant effluents have been extensively studied, due to concerns over the effects chlorinated organics may have on the aquatic life in the receiving waters24,25,26.

Mills have been progressively moving toward bleaching with chlorine dioxide and other chlorine substitutes. Full chlorine substitution in elemental chlorine free (ECF) and totally chlorine free (TCF) bleaching has reduced Microtox® toxicity by a factor of two to four27. As TCF bleaching does not result in new chlorinated organics, the remaining effluent toxicity is attributed to natural wood origin28.

24 Catesm D.H.; Eggert, C.; Yang, J.L.; and Eriksson, K.L. "Comparison of Effluents from TCF and ECF Bleaching of Kraft Pulps" in Tappi Journal, 78(12), pp. 93-98. 25 Fuller, W.A. " Is AOX obsolete as a regulatory parameter for bleached kraft pulp mill effluent?" from University of Alberta Internet website http://stud1.acad.athabascau.ca/html/groups/fota/aox.html, accessed November 17, 1998. 26 Ahtiainen, J.; Nakari, T.; and Silvonen, J. "Toxicity of TCF and ECF Pulp Bleaching Effluents Assessed by Biological Toxicity Tests" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 33-40. 27 Eklund, B.; Linde, M.; and Tarkpea, M. "Comparative Assessment of the Toxic Effects from Pulp Mill Effluents to Marine and Brackish Water Organisms" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 95- 105. 28 Verta, M.; Ahtiainen, J.; Nakari, T.; Langi, A.; and Talka, E. "The Effect of Waste Constituents on the Toxicity of TCF and ECF Pulp Bleaching Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 41- 51. 7

A significant exponential relationship was reported for low molecular weight (<

1,000 Daltons) AOX and log-transformed values for chronic effects in Ceriodaphnia and a somewhat weaker relationship in fathead minnows29. However, this may be a casual correlation as AOX concentrations are also interrelated with organic material30. Other studies have not been able to link AOX and toxicity; in fact, significant reductions in

AOX and other chlorinated organics did not lead to significant improvements in bioassay response31,32. It may be more likely that the organic constituents contribute to final effluent chronic toxicity.

Nevertheless, this may identify a need to selectively remove the low molecular weight organics from process streams. Low molecular weight compounds (less than

1,000 Daltons) are usually, but not always, associated with toxicity. One reason is that high molecular weight materials are less likely to cross biological membranes.

In general, the amount of chlorinated organics has reduced with the substitution of chlorine dioxide for elemental chlorine bleaching. The toxicity associated with ECF and

29 Fuller, W.A. " Is AOX obsolete as a regulatory parameter for bleached kraft pulp mill effluent?" from University of Alberta Internet website http://stud1.acad.athabascau.ca/html/groups/fota/aox.html, accessed November 17, 1998. 30 Kemeny, T.E. and Banerjee, S. "Correlations Among Contaminant Profiles in Mill Process Streams and Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 151-158. 31 Verta, M.; Ahtiainen, J.; Nakari, T.; Langi, A.; and Talka, E. "The Effect of Waste Constituents on the Toxicity of TCF and ECF Pulp Bleaching Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 41- 51. 32 Hall, T.J.; Haley, R.K.; Borton, D.L.; and Bousquet, T.M. "The Use of Chronic Bioassays in Characterizing Effluent Quality Changes for Two Bleached Kraft Mills Undergoing Process Changes to Increased Chlorine Dioxide Substitution and Oxygen Delignification" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 53- 67. 8

TCF bleaching is less than that for processes using elemental chlorine.33 However, toxicity has not been eliminated. As such, more focus should be placed on the role of naturally occurring components of the wood on final effluent residual toxicity.

Natural Components

Natural components present in effluents include polysaccharides, lignin, extractives and inorganics. Wood extractives, which are species dependent, include

terpenoids, steroids, fats, waxes, phenolics and inorganics. The inorganics are comprised

mainly of metal salts, including carbonates, silicates and phosphates of calcium,

potassium and magnesium. Bark contains many of the same extractives compounds, only

at higher concentration than in the wood.

Resin acids are diterpenoid carboxylic acids and one of the dominant species

present in the oleoresin in softwood resin canals. Their purpose is to protect the wood

against microbial and insect damage. In view of their function, it is not surprising that

they are acutely toxic to fish and other aquatic life34. The resin acid concentration in

mechanical pulp mills is greater than chemical pulp mills. This is due to chemical pulp

mill processes such as chemical recovery and tall oil collection. The chemical structures

of common tricyclic resin acids found in wastewater effluents are shown in Figure 1.1. In

this figure, the structures are numbered as follows: pimaric (1); sandaracopimaric (2);

33 Ahtiainen J., Nakari T., and Silvonen, J. (1996) Toxicity of TCF and ECF pulp bleaching effluents assessed by biological toxicity tests, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 33-40. 34 These compounds are often cited as the principal cause in acute toxicity outbreaks, such as fish kills. 9

isopimaric (3); abietic (4); levopimaric (5); palustric (6); neoabietic (7); and

dehydroabietic (8). The first three resin acids are of the pimarane type, distinguished by

vinyl and methyl groups at the C13 position. The last five are the abietane type with isopropyl or isopropenyl groups at C13.

Figure 1.1 Chemical structures of natural extractive wood components35.

Fatty acids are formed during pulping as the hydrolysis products of esters, namely

fats and waxes. These are long chain (C18-C24) carboxylic acids with varying degrees of saturation. Table 1.1 lists the most common fatty acids found in effluent streams. Palmitic and stearic are saturated, while oleic and linoleic are unsaturated acids.

35 Sjostrom, E. “Extractives” in Wood Chemistry: Fundamentals and Applications, 2nd ed., Academic Press, Inc., San Diego, (1993), p. 100. 10

Table 1.1. Fatty acids most commonly found in wastewater streams.

Common name Systematic name Chain length Palmitic Hexadecanoic C16 Stearic Octadecanoic C18 Oleic cis-9-Octadecenoic C18 Linoleic cis,cis-9,12- Octadecadienoic C18

Effluent toxicity has persisted even with the progressive reduction in elemental

chlorine use as a bleaching agent. It has long been known that natural wood components

are major contributors to effluent toxicity36. Wood extractives, specifically resin and

fatty acids, can account for more than 70% of effluent toxicity in mechanical and

chemical mills37,38. A recent study in ECF/TCF mills in Finland found resin and fatty acids and phenols accounted for 80% of the residual toxicity39. The regression equation

related the concentrations of these components to composite toxicity by:

TI = 0.006 [Phenols] + 0.032 [Fatty Acids] + 0.048 [Resin Acids] - 0.02 (1-1)

where TI is the toxicity index and concentrations are expressed as mgL-1.

36 Leach, J.M. and Thakore A.N. "Compounds Toxic to Fish in Pulp Mill Waste Streams" Progress in Water Technology, 9(4), (1978), pp. 787-798. 37 Leach, J.M. and Thakore A.N. "Compounds Toxic to Fish in Pulp Mill Waste Streams" Progress in Water Technology, 9(4), (1978), pp. 787-798. 38 Werker, A.G.; Bicho, P.A.; Saddler, J.N.; and Hall, E.R. "Surface Tension Changes Related to the Biotransformation of Dehydroabietic Acid by Mortierella Isabellina" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 139-150. 39 Verta, M.; Ahtiainen, J.; Nakari, T.; Langi, A.; and Talka, E. "The Effect of Waste Constituents on the Toxicity of TCF and ECF Pulp Bleaching Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 41- 51. 11

However, this correlation was developed based on a combination of field and

pilot treated effluent data. The laboratory data were needed to provide additional points

for correlation development beyond the field samples from the treatment system influent

and effluent. This is due to the high toxicity and concentration of many organics in

untreated effluents and the relatively benign effects of the treated effluent. A need exists

to develop data for the points in between to validate laboratory findings, i.e. by

measuring changes during secondary effluent treatment. Toxicity measurements across

the pond have never been correlated with concentrations of the compounds present.

Specifically, changes in toxicity across treatment may correlate with changes in resin and

fatty acid concentration.

Table 1.2 illustrates the range of acute toxicity values of these components as

expressed in LC50 for rainbow trout. It can be seen that resin acids are acutely toxic at very low concentrations based on these findings. It is also clear that phenols are acutely

toxic at the same order of magnitude as resin and fatty acids. However, the regression

coefficient for phenols in Equation 1-1 is an order of magnitude less than those for resin and fatty acids. This may indicate that phenols play a less significant role in effluent toxicity than resin and fatty acids.

Many recalcitrant and toxic materials are resin acid derivatives; for example, chlorinated dehydroabietic acid and retene are derived from dehydroabietic acid40. Thus,

40 Bicho, P.; Liss, S.; and Sadler, J. "Microbiology and Biodegradation of Resin Acids in Pulp-Mill Effluents: A Minireview" in Canadian Journal of Microbiology, 43(7), pp. 599-611. 12

changes to resin acids during processing or secondary treatment may account for much of the final effluent toxicity.

Table 1.2: LC50 (Rainbow trout) of key extractives41.

Compound LC50 mg L-1 Phenols 0.15 - 10.5 Fatty acids 0.32 – 8.2 Resin acids 0.32 – 1.7

In summary, natural wood components are significant sources of effluent toxicity, though the contribution to residual chronic toxicity in ECF/TCF mills is not known.

Among toxic effluent mixtures, resin acids are consistently reported as major components42,43,44,45.

1.3. Effluent treatment systems

Effluent treatment systems are used to control the quality of wastewater discharged to receiving waters. Important water quality parameters include temperature, pH, dissolved oxygen, biochemical oxygen demand (BOD), color, turbidity, and toxicity.

Typically, modern pulp and paper mill effluent treatment processes include primary and

41 Verta, M.; Ahtiainen, J.; Nakari, T.; Langi, A.; and Talka, E. "The Effect of Waste Constituents on the Toxicity of TCF and ECF Pulp Bleaching Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 41- 51. 42 Verta, M.; Ahtiainen, J.; Nakari, T.; Langi, A.; and Talka, E. "The Effect of Waste Constituents on the Toxicity of TCF and ECF Pulp Bleaching Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 41- 51. 43 Leach, J.M. and Thakore A.N. "Compounds Toxic to Fish in Pulp Mill Waste Streams" in Progress in Water Technology, 9(4), (1978), pp. 787-798. 44 Bicho, P.; Liss, S.; and Sadler, J. "Microbiology and Biodegradation of Resin Acids in Pulp-Mill Effluents: A Minireview" in Canadian Journal of Microbiology, 43(7), pp. 599-611. 45 LaFleur, L.E. "Sources of Pulping and Bleaching Derived Chemicals in Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 21-31. 13

secondary treatment, and less commonly tertiary treatment. The goal of primary

treatment is to remove solids from the wastewater by allowing them to settle out in

gravity sedimentation tanks, or in some cases with the aid of flotation. The use of primary clarifiers became widespread in the late 1950s46. Since the 1960s, most mills also use a secondary treatment process as well, which involves reacting the primary-treated effluent with oxygen and microorganisms to remove oxygen-consuming materials and decreases the effluent toxicity significantly. The two most common secondary treatment processes are aerated stabilization basins (ASBs) and activated sludge treatment (AST).

ASBs are similar to natural oxidation basins with the addition of aerators to improve oxygen transfer and increase efficiency. Typically nutrients such as nitrogen and phosphorous are added to control microbe community growth and structure. Overall reduction of BOD is related to system residence time and biological activity. ASBs are

characterized by lower biological activity and higher residence time (system volume)

relative to ASTs. Activated sludge processes reduce the residence time required to

effectively treat wastewaters by maintaining a higher level of biological activity in the

process. This is accomplished by recycling biomass in the mature stage of the growth

curve (i.e. “activated sludge”) from the end of the process back to the beginning. The

increase in biomass is matched with higher oxygen transfer to mineralize organics in less

time (space). Tertiary treatment processes, which are the most advanced types of

treatment, follow secondary treatment and are often used for the removal of color.

46 Biermann, C.J. (1996) “Environmental impact: aqueous effluent treatment” in Handbook of pulping and papermaking. 2nd ed., San Diego: Academic Press. Pp. 287-290. 14

Examples of tertiary treatment include flocculation, ultrafiltration and carbon adsorption.

Economics limit the use of such processes.

Effluent treatment systems are generally effective in removing the majority of

pulp and paper mill compounds to concentrations below their individual toxic

concentration levels47,48. However, final treated effluents still typically exhibit chronic

toxicity at full effluent strength, as shown in a study of more than 500 tests in Canada in

Figure 1.2.

Figure 1.2. Summary of Ceriodaphnia dubia reproduction test in Canada49.

47 Liss S.M., Bicho P.A. and Saddler J.N. (1997) Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview. Can. J. Microbiol., 75, 599-611. 48 Mörck R., Jansson M.B., and Dahlman O. (2000) Resinous compounds in effluents from pulp mills in “Pitch Control, Wood resin and Deresination” (Back E.L. and Allen, L.H. Eds.), Tappi Press, Atlanta, GA. 49 Environment Canada. National Assessment of Pulp and Paper Environmental Effects Monitoring Data: A Report Synopsis. National Water Research Institute, Burlington, Ontario. NWRI Scientific Assessment Report Series No. 2.(2003) p. 19. 15

In this figure, “Cycle 1” and “Cycle 2” represent data collected in 1996 and 2000,

respectively. The vertical bars indicate the percentage of tests conducted during 1996 and

2000 in which the C. dubia exhibited a 25 percent decrease in reproduction at that

threshold of concentration (IC25). In 2000, 74% of tests exhibited this chronic toxic response for effluents diluted to less than full-strength. The total percentage of tests resulting in a toxic response is unclear, as the data for full-strength effluent has been grouped with samples not exhibiting an IC25 (i.e. less than a 25% decrease in reproduction at 100% concentration). Regardless, it is clear that even though individual components may not be identified at binary aqueous toxicity threshold concentrations, the aggregate treated effluent generally has an adverse effect on aquatic life prior to dilution in receiving waters.

1.4. Sources of Toxic Components

Sources of toxic components entering effluent treatment have been studied and partially identified50,51. These include the sewers of the wood yard, pulp mill, evaporator, recovery, and bleach plant.

As bark contains high concentrations of extractives, storage in the wood yard and debarking can be a significant source of organics. Dry debarking has significantly

50 LaFleur, L.E. "Sources of Pulping and Bleaching Derived Chemicals in Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 21-31. 51 Banerjee, S. "A Long-Term Study of Process Sewer and Effluent Constituents at the Georgia-Pacific Leaf River Facility," IPST Project 3866 Report, Atlanta, GA, (1994). 16

reduced the amount of leached organics in the wood yard wastewater52. However, environmental variations, such as rain in the woodyard, can cause these extractives to

enter the treatment system. If this is a low volume, high concentration stream (or can be

concentrated) diversion to the recovery boiler may be an option.

The pulp mill sewer can represent a major flow into the effluent treatment

system53. The makeup of this stream is poorly defined but can contain black liquor

(spills), brownstock wash water, decker filtrates and the associated organics and inorganics. Phenolic compounds mainly occur as lignin degradation products. Black liquor spills can cause spikes in the chemical profile of not only the pulp mill sewer, but also throughout the entire system. Black liquor spill minimization, containment and recovery could reduce this loading, as well as brownstock washer/decker filtrate closure.

However, unless all of the mill process streams can be sent directly to the recovery boiler, a purge point for the organics will be necessary.

The evaporator sewer condensates include low molecular weight alcohols, aldehydes and ketones, terpenes, sulfur compounds and phenolics54. Most of these constituents are either volatile or have been carried over during liquor concentration. The recovery sewer condensates can represent a small, but not insignificant source of

52 LaFleur, L.E. "Sources of Pulping and Bleaching Derived Chemicals in Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 21-31. 53 Banerjee, S. "A Long-Term Study of Process Sewer and Effluent Constituents at the Georgia-Pacific Leaf River Facility," IPST Project 3866 Report, Atlanta, GA, (1994). 54 LaFleur, L.E. "Sources of Pulping and Bleaching Derived Chemicals in Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 21-31. 17

inorganics and organics to effluent treatment systems. The bleach plant sewers can be

divided into acid and alkaline effluents. The amount of chlorinated organics in these

streams depends on pulping, washing, bleach plant parameters and process closure.

Alkaline extracts typically have higher concentrations of resin and fatty acids due to

increased solubility at elevated pH. Acid effluents often bypass primary treatment and

proceed directly to the equalization basin.

The sources of the contaminant are important, as these will likely be the most

concentrated streams. For resin acids, the sewers of the pulp mill, evaporator, and

alkaline filtrate have been identified as the most concentrated sources at one mill55. More generally, any sewer stream from the brown stock washer or decker may be highly concentrated with dissolved and colloidal organics.

1.5. Partitioning of Resin Acids

Natural separation processes exist throughout the pulp mill and effluent treatment system. Organics partition between environmental compartments based on physicochemical properties affecting solubility, volatility, hydrophobicity, and surface activity.

Understanding this behavior provides insight into the compounds that are possible bad actors and ones that likely are not. For example, turpentine compounds, such as α-pinene, may or may not be toxic to aquatic organisms if present in the final effluent. However, these compounds are effectively stripped from the effluent treatment system due to their high activity coefficient in water relative to air. As such, α-pinene cannot contribute to

55 Banerjee, S. "A Long-Term Study of Process Sewer and Effluent Constituents at the Georgia-Pacific Leaf River Facility," IPST Project 3866 Report, Atlanta, GA, (1994). 18

final effluent toxicity. On the other hand, normally insoluble compounds can be made

soluble during pulping, such as the saponification of extractive esters in highly alkaline

pulping liquors. This causes a higher concentration of resin acids in wastewater wash

streams. One result of this partitioning is the need for additional separation processes to

treat the effluent streams.

Processes in the pulp mill that partition organics from process to effluent streams

include: leaching/evaporation in the woodyard; pulping; turpentine and tall oil collection;

brownstock washing; alkaline extraction; acid washing; evaporation; recovery spills into

sewers; stripping; pH variations in the various sewers; and sorption in primary and

secondary treatment. The fate of organics may be determined by their partitioning

coefficients in the various process environments. The objective of most of these

processes is to remove the organics (dissolved lignin, extractives) from the pulp, but not

all are sent to effluent treatment. Generally, debarking wastewater, sewered condensates,

some spills, brownstock and decker filtrates, screening wastewater, and bleach plant

filtrates are sent to treatment ponds56.

Turpentine collection, which removes much of the volatiles (monoterpenes),

occurs during pulping. Resin and fatty acids are saponified during pulping, and are

usually present as sodium soaps. Tall oil collection occurs at various points during

56 Servos, M.R. "Origins of Effluent Chemicals and Toxicity: Recent Research and Future Directions" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 159-166. 19

pulping and recovery, but principally from a skimmer in the evaporator train57.

Separation is located at approximately 20 % black liquor solids. Tall oil is also collected in the foams of the weak black liquor. This is due to the increased concentration of soap in the foam. The amount of tall oil available in southern pine varies from 35-45 kg/ODMT wood58. However, not all of this is recoverable due to losses and collection method limitations. Losses occur throughout pulping and recovery and few mills determine tall oil soap losses. Tall oil sorbs to hydrophobic fibers more strongly than black liquor solids59. Washers are controlled to limit black liquor carryover; resin acids are not monitored. Approximately 25% of the soap may be left with the pulp leaving the brownstock washers60. Brownstock washing and alkaline extraction during bleaching sends much of these resin and fatty acids to effluent treatment.

The main removal mechanisms for resin and fatty acids are biodegradation during aerobic secondary treatment and sorption to biosolids61,62. Removal rates vary, but typically greater than 95% of the resin and fatty acids entering the pond do not exit63.

57 Propst, M. and Drew, J. "Tall Oil Soap Recovery" in Tappi Kraft Recovery Operations Seminar Proceedings, Tappi Press, Atlanta, GA, (1987), pp. 109-112. 58 Foran, C.D. "Tall Oil Soap Recovery" in 1996 Kraft Recovery Short Course Notes, Tappi Press, Atlanta, GA, (1996), Session 4, Paper no. 3, pp. 1-31. 59 Drew, J. and Propst, M. “Tall oil soap recovery”, in Tall Oil, published by the Pulp Chemicals Association, New York, (1981) p. 17. 60 Propst, M. and Drew, J. "Tall Oil Soap Recovery" in Tappi Kraft Recovery Operations Seminar Proceedings, Tappi Press, Atlanta, GA, (1987), pp. 109-112. 61 Bicho, P.; Liss, S.; and Sadler, J. "Microbiology and Biodegradation of Resin Acids in Pulp-Mill Effluents: A Minireview" in Canadian Journal of Microbiology, 43(7), pp. 599-611. 62 Williams, C.L.; Mahmood, T.; Corcoran, H.; Zaltzmann, M.E.; and Banerjee, S. "Tracing the Efficiency of Secondary Treatment Systems" in Environmental Science & Technology, 31(11), (1997), pp. 3288-3292. 63 Stromberg, L.; Morck, R.; de Sousa, F; and Dahlman, O. "Effects of Internal Process Changes and External Treatment on Effluent Chemistry" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 3-19. 20

Sorbed resin acid fate in receiving waters is typically dispersal and sedimentation64.

Volatiles, phenols, mono- and dichlorophenols are typically removed during secondary treatment65,66.

Separation processes are based on selective partitioning of one component from a

mixture or solution due to differences in their physical and chemical properties. These

properties include solubility, vapor pressure, density, molecular size and shape, ionic

charge, and surface activity.

Many wastewater separation processes are been based on exploiting differences in

these properties. The objective is typically to maximize removal efficiencies based on

certain system parameters. However, far fewer studies attempt to understand the basic

interactions responsible for the observed distributions. For example, flotation studies to

remove toxicity from pulp mill effluents date back more than twenty five years67. The system studied was complicated; real mill effluents include interactions between the resin acids and air, water, and solids, not to mention other organics. However, little more was learned than the time required to remove maximum toxicity (~90%) by foam fractionation, and the resulting unwieldy volume (~ 20 % of the total volume treated) of

64 Carlberg, G.E. and Stuthridge, T.R. "Environmental Fate and Distribution of Substances" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 169-178. 65 Stromberg, L.; Morck, R.; de Sousa, F; and Dahlman, O. "Effects of Internal Process Changes and External Treatment on Effluent Chemistry" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 3-19. 66 Fisher, R.P.; Barton, D.A.; Wiegand, P.S. "An Assessment of the Significance of Discharge of Chlorinated Phenolic Compounds from Bleached Kraft Pulp Mills" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 107-117. 67 Mueller, J.C.; Ng, K.S.; and Walden, C.C. "Detoxification of Kraft Mill Effluents by Foam Separation" in Pulp & Paper Canada, 74(5), (1973), pp. 119-123. 21

the reject stream. Thus, the approach is not novel, yet little basic understanding has been

added to the mechanism of partitioning at the air-water and water-fiber interfaces.

Previous flotation studies have looked at foam separation to detoxify pulp mill

effluents68,69,70. Trials have been conducted at the laboratory and pilot scale levels. Often the experimental apparatus was crude and difficult to control system variables. For example, one pilot scale apparatus consisted of a foam generation plywood tank with a

60-minute retention time. No mechanical device was necessary to remove the foam, as it was allowed to overflow out of the tank. Efficiency was measured as the retention time required for detoxification.

The findings indicated that treating the whole effluent was more effective than treating any one of the sewers. However, this was due to severe limitations in the design of experiments. For instance, only actual process streams were used, with the associated process conditions. Critical parameters such as pH and temperature were not controlled

and little insight was gained into the fundamentals governing the process. A system

based on this configuration does not appear feasible due to the high volume of effluent

that must be removed as foam. A lower volume, higher concentration stream should be

targeted for removal of resin acids by flotation.

68 Mueller, J.C.; Ng, K.S.; and Walden, C.C. "Detoxification of Kraft Mill Effluents by Foam Separation" in Pulp & Paper Canada, 74(5), (1973), pp. 119-123. 69 Mueller, J.C.; Ng, K.S.; and Walden, C.C. "Process Parameters of Foam Detoxification of Kraft Effluent" in Pulp & Paper Canada, 75(7), (1974), pp. 101-106. 70 Gutierrez, L.A.; Mueller, J.C.; Ng, K.S.; and Walden, C.C. "Detoxification of Kraft Mill Effluents by Foam Separation - Pilot Plant Studies" in Pulp & Paper Canada, 80(11), (1979), pp. 87-92. 22

The brownstock washer/decker filtrate is a major source of organics and

inorganics, however, this stream is often sewered due to low solids concentration. The

brownstock washer filtrate typically contains up to 1-2 % black liquor solids. The

economic break point for evaporating this stream is approximately 4-4.5 %71. This is assuming that sufficient evaporator capacity exists to handle this excess loading.

Therefore, flotation may be an efficient method to concentrate organics enough to be sent to the evaporators and then the recovery boiler. However, more basic understanding of the interactions dominating resin acid distribution in air-water-solid systems is needed.

This understanding will allow for the prediction of resin acid partitioning in systems well beyond the scope of this project.

71 Personal communication on December 10, 1998 with Thomas E. Kemeny, a pulping, bleaching and environmental consultant. 23

1.6. Section Summary

Hundreds of compounds are released from the Kraft pulping process into the wastewater treatment system72,73. Many of these compounds enter the effluent treatment system (ETS) at toxic levels74. With proper operation, most treatment systems are effective at reducing individual compound loading to the mill’s receiving waters to concentrations below the toxic thresholds reported in literature75. However, even though no individual compound may be present at acutely toxic levels, treated mill effluents often exhibit chronic toxicity at 100% strength prior to dilution in receiving waters, as shown in Figure 1.2.

Said another way, many compounds contribute to ETS influent toxicity but the contribution of these same compounds to final effluent toxicity is difficult to assess. Yet comparing changes in influent and effluent profiles has been the approach taken in many efforts to empirically relate the contribution of chemical compounds present in real mill effluents to treated effluent toxicity76,77. Relationships have been developed between naturally occurring compound groups, such as resin acids, fatty acids, and phenols, and

72 Suntio, L.R., Shiu, W.Y., Mackay, D. A review of the nature and properties of chemicals present in pulp mill effluents. Chemosphere 17 (1988) pp. 1249-1290. 73 McKague A. B., Chew W., Zhu S., and Reeve, D. W. Compounds identified in effluents from the bleaching of wood pulp, in Proceedings of the International Pulp Bleaching Conference. Helsinki (1998) pp. 205–212. 74 Ard, T.A. and McDonough T.J. "Toxicity Assays in the Pulp and Paper Industry- A Review and Analysis," IPST Technical Paper Series 608, Atlanta, GA, (1996). 75 Morck R., Jansson M.B., and Dahlman O. (2000) Resinous compounds in effluents from pulp mills in “Pitch Control, Wood resin and Deresination” (Back E.L. and Allen, L.H. Eds.), Tappi Press, Atlanta, GA. 76 Verta, M.; Ahtiainen, J.; Nakari, T.; Langi, A.; and Talka, E. "The Effect of Waste Constituents on the Toxicity of TCF and ECF Pulp Bleaching Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 41- 51. 77 Cook, D.; Parrish, A.; Borton, D.; and Hall, T. "A Summary of Pulp and Paper Mill Experiences with Toxicity Reduction and Toxicity Identification Evaluations (TRE/TIE)" in 1998 International Environmental Conference & Exhibit Proceedings, Tappi Press, Atlanta, GA, (1998), pp. 1081-1094. 24

composite toxicity measures of final treated effluents78. The data represent actual concentrations and toxicity levels before and after secondary treatment, or at fractional residence times of 0 and 1. Data from laboratory bioreactors have been employed to estimate concentrations of compound groups and acute toxicity at intermediary residence times. This approach is useful to the extent to which the laboratory data reflect reality.

The main contributors to final effluent acute toxicity were found to be resin and fatty acids, and to a lesser extent phenols, which in total accounted for 80% of the variation79.

These findings have not been extended to the effect of these compounds on individual chronic toxicity assays . Also of interest are the interactions of resin and fatty acids with pulp-derived solids.

Furthermore, these results have not been validated in a full-scale ETS. However, some implications can be made based on these relationships if they also hold for industrial operations. First, during normal operating conditions, the effectiveness of resin and fatty acid (RFA) removal would be an important parameter to monitor to predict effluent acute toxicity levels. Second, process improvements that reduce the loading of

RFAs to the ETS would also reduce the risk for effluent toxicity problems. Finally, the ability of the ETS to remove increased RFA levels due to process upsets would impact the resulting effluent toxicity levels.

78 Verta, M.; Ahtiainen, J.; Nakari, T.; Langi, A.; and Talka, E. "The Effect of Waste Constituents on the Toxicity of TCF and ECF Pulp Bleaching Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 41- 51. 79 Verta, M.; Ahtiainen, J.; Nakari, T.; Langi, A.; and Talka, E. "The Effect of Waste Constituents on the Toxicity of TCF and ECF Pulp Bleaching Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 41- 51. 25

In particular, laboratory-scale studies have shown that even biomass cultures

specifically acclimated to mineralizing a “normal” level of RFA cannot adequately

respond to a RFA shock loading (for example an impulse or step-change functions)80.

The specific implications of these results depend on the mixing characteristics and mean residence time of the ETS. In general, the expected result is a higher RFA concentration in the final treated effluent discharged from the ETS. If RFA concentration in the final effluent is related to acute and chronic toxicity, then it is expected that RFA shock loading will result in elevated final effluent toxicity for extended periods of time. The length of such toxicity “outbreaks” will be related to the magnitude and duration of the shock load, ETS mixing and residence time, and biomass activity and community structure specific to each system and situation.

80 Werker, A.G. and Hall, E.R. (2000) The fate of a resin acid shock load in a biological system. Pulp and Paper Canada 101 (1), 45-49. 26

2. Dissertation Questions and Research Objectives

The findings of the prior research and the resulting implications have prompted the following dissertation questions:

• Will changes in resin and fatty acid (RFA) concentration across a full-scale

effluent treatment system correlate with changes in acute toxicity?

• Do RFAs exhibit a similar relationship with chronic toxicity?

• Is there a concentrated source stream in the pulp mill with operational

parameters promoting selective removal?

• What will be the dominant mechanism for RFA removal from pulp mill

streams using flotation?

The dissertation questions are based on the premises that:

As resin acids are some of the more recalcitrant organics in the ETS, the extent to which RFAs are removed will significantly influence the acute and chronic toxicity levels of the treated effluent.

Full-scale ETSs cannot effectively remove shock loads of RFAs, thus a need exists for pulp mills to develop alternative RFA removal systems in order to reduce the risk of toxicity outbreaks associated with process upsets.

Resin and fatty acids are both hydrophobic and surface active, the extent of which

depends on process conditions and will influence the probability of removal by flotation.

2.1. Research Objectives

Since resin acids are known to be resistant to biological degradation, it is expected

that the removal of these compounds will require longer residence times in the ETS than

other organic compounds. Thus, if samples are compared across the ETS at various

residence times, a better picture can be developed of how RFAs relate to effluent toxicity.

Furthermore, resin and fatty acids are hydrophobic and are expected to interact with hydrophobic materials in the ETS, such as biomass and pulp-derived solids. The specific effect of these interactions is of interest, as RFAs that are not in the water column are not bioavailable and as such must be initially removed from the ETS by a mechanism other than mineralization.

If full-scale ETS systems cannot respond quickly enough to higher loads of RFAs due to process upsets, then the effect of increased levels of RFAs in the treated effluent on toxicity should be considered. By using a model resin acid, such as dehydroabietic acid (DHA), a toxic threshold concentration in the final effluent can be determined. Mills will be able to compare these measures with typical concentration ranges in the treated effluent and quantify their risk of experiencing resin acid related toxicity problems.

The following research objectives were defined based on the dissertation questions and the underlying hypotheses:

• Determine the relationship between changes in resin acid concentration and

changes in acute toxicity, using the Microtox® whole effluent test bioassay,

across the effluent treatment system of an integrated Kraft mill.

• Determine the relationship between changes in resin acid concentration and

changes in chronic toxicity, using the Ceriodaphnia dubia 7-day survival and

reproduction bioassay, across the ETS.

• Determine the effect of total suspended solids (TSS) on the removal of resin

and fatty acids in the ETS.

• Simulate a black liquor spill effect on the final effluent RFA concentration by

introducing a DHA spike in treated effluent and determine the toxic

concentration of DHA, as defined in acute and chronic bioassays.

• Determine the amount of RFA entering primary treatment, the fraction sorbed

to TSS and the removal percentage

• Map the pulp mill sewer system to identify major RFA source streams of

relatively low-volume and high-concentration.

• Determine the influence of TSS, pH, and temperature on RFA removal

efficiency from pulp mill streams using flotation.

• Determine the influence of bubble size, superficial gas velocity, and treatment

time on RFA removal efficiency from pulp mill streams using flotation.

The next section explains how the research objectives were translated into an experimental design, as well as the thesis organization.

2.2. Thesis Approach

The research objectives can be addressed according to the following experimental design matrix:

Objectives Field Studies Laboratory Studies Relationship between RFA Full-scale ETS correlation Toxicity of DHA in real and effluent toxicity between RFA and toxicity mill effluent Removal of RFA from pulp Map mill sewer system for Removing RFA from pulp mill source stream RFA contribution to ETS mill streams using flotation

In order to answer the dissertation questions, a research project was designed to:

• Measure changes in RFA concentration, general effluent parameters (TSS,

COD, DO, pH, and temperature), and acute and chronic toxicity across a full-

scale ETS.

• Simulate a process spike in the concentration of dehydroabietic acid (DHA),

to determine the acute and chronic toxicity threshold in a real mill effluent

using controlled laboratory experiments.

• Map the pulp mill sewer system to identify major RFA source streams of

relatively low-volume and high-concentration.

• Apply the results and implications of this work to the development of a

flotation process targeted at the selective removal of RFAs from a pulp mill

source stream.

As each of these four studies build upon the results of the previous study, each study is detailed individually. The following four sections describe the approach taken, experimental procedures, results and discussion for each of the studies. The four sections detailing the specific studies are:

• RFA and Toxicity Removal Across the ETS;

• DHA Acute and Chronic Toxicity;

• Mapping Pulp Mill Sewers for RFA Loading to the ETS; and

• Resin and Fatty acid Removal from Pulp Mill Sewers using Flotation.

Following these sections are the Conclusions and Recommendations, which serve to unite the dissertation results and discuss implications for academia and industry.

3. RFA and Toxicity Removal Across the ETS

3.1. Section Overview

Although many of the constituents that enter secondary treatment are toxic to aquatic organisms, a sizable fraction of these are removed during treatment81. Resin acids occur naturally in softwood and have been repeatedly implicated as contributors to effluent toxicity82,83,84,85,86. Of these, dehydroabietic acid (DHA) is of particular concern because it can be anaerobically reduced to retene87, which is toxic to aquatic organisms.

Reports on the mechanism of resin acid removal are conflicting. Zender et al.88 attribute the removal of DHA under field conditions to biodegradation, and DHA has been shown to be biodegradable in the laboratory89. Typically, treatment systems are able to efficienly remove low influent concentrations of resin and fatty acids. Yet, laboratory-scale work shows that even microorganisms acclimated to resin acids were unable to degrade a shock load because of a long lag period90,91. DHA and other resin acids are hydrophobic

81 Morck R., Jansson M.B. and Dahlman O. (2000) Resinous compounds in effluents from pulp mills in “Pitch Control, Wood resin and Deresination” (Back E.L. and Allen, L.H. Eds.), Tappi Press, Atlanta, GA. 82 Leach J.M., Mueller J.C. and Walden C.C. (1976) Identification and removal of toxic materials from kraft and groundwood pulp mill effluents. Process Bioch 11(1) J7-J10. 83 Leach J.M. and Thakore A.N. (1976) Toxic constituents in mechanical pulping effluents. Tappi J. 59(2), 129-132. 84 Liss S.M., Bicho P.A. and Saddler J.N. (1997) Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview. Can. J. Microbiol., 75, 599-611. 85 Peng G. and Roberts J.C. (2000) Solubility and toxicity of resin acids, Wat. Res., 34(10), 2779-2785. 86 Zanella A. (1983) Effect of pH on acute toxicity of dehydroabietic acid and chlorinated dehydroabietic acid to fish and Daphnia. Bull. Environm. Contam. Toxicol., 30, 133-140. 87 Liss S.M., Bicho P.A. and Saddler J.N. (1997) Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview. Can. J. Microbiol., 75, 599-611. 88 Zender J.A., Stuthridge T.R., Langdon A.G., Wilkins A.L., Mackie K.L. and MacFarlane P.N. (1994) Removal and transformation of resin acids during secondary treatment at a New Zealand bleached kraft pulp and paper mill. Wat. Sci. Tech., 29(5,6), 105-121. 89 Leach J.M., Mueller J.C. and Walden C.C. (1976) Identification and removal of toxic materials from kraft and groundwood pulp mill effluents. Process Bioch 11(1) J7-J10. 90 Werker A.G. and Hall E.R. (1999) Limitations for biological removal of resin acids from pulp mill effluent. Wat. Sci. Tech. 40(11,12), 281-288. 91 Werker A.G. and Hall E.R. (2000) The fate of a resin acid shock load in a biological system. Pulp and Paper Canada 101 (1), 45-49. 32

species capable of sorption to fiber and biomass present in the treatment system. Hence, sorption of DHA to suspended solids and their subsequent settling must play some role.

The relationship between resin acids, their partial removal from the water column by partitioning to total suspended solids, and effluent toxicity is unclear.

The primary objective of this chapter is to clarify the importance of sorption/settling of RFAs in general, and DHA specifically, through studies on full-scale treatment systems and to determine its implications on effluent toxicity. This section reports the findings of 14 collection trips to three integrated pulp and paper mills.

Samples were collected across the treatment system and analyzed for resin and fatty acids, toxicity and general water quality parameters.

3.2. Experimental Approach

In studying a complex system, such as an industrial wastewater treatment system, many key parameters will not be subject to experimental control. Indeed, it is apparent that considerable variation exists in normal effluent treatment systems (ETS) operating parameters, including:

• Temperature, and to a lesser extent pH;

• Influent flow rate and contaminant mass loading, and therefore initial

concentrations;

• Mean residence time and mixing;

• Biomass activity and community structure; and

• Dissolved oxygen and nutrients.

These parameters fluctuate due to:

• Expected variations due to changes in the raw materials being processed,

process improvements and maintenance;

• Unexpected variations due to process upsets including black liquor spills; and

• External factors such as seasonal effects.

The effect of these variations will impact the efficiency that the treatment system has in removing detrimental compounds. It is therefore expected that significant variation will be observed in the absolute levels of the influent and effluent concentrations of RFAs in the ETS.

The inability to control the operating parameters of the ETS makes it necessary to define ranges of “normal” operating conditions. By identifying these ranges, the results of this research may be more directly comparable with other treatment systems. A long-term study must be undertaken to incorporate the effects of variations in raw materials processed, process upsets and seasonal variations on ETS operating performance.

Otherwise generalizations cannot be made from the results of discrete sampling events.

It is important to note that this study tracks few of the hundreds of individual compounds entering the effluent treatment system. Inferences are made from the

comparison of RFA removal efficiency with measures of toxicity and total organic

loading (COD) reduction. In particular, measuring RFA and COD concentrations, as well

as toxicity levels, at progressive ETS residence times allows for deeper insight than

studies solely measuring inlet and outlet conditions.

3.3. Experimental

The bulk of the study was conducted at Mill A, which is located in the

Southeastern US. Its pulp production consists of 20% bleached hardwood, 30% bleached

softwood, and 50% unbleached softwood. The bleaching sequences are (CD)(EOP)HD

for the softwood and CEHD for the hardwood. It should be noted that Mill A was

increasing chlorine substitution over the course of this study. Approximately 32 MGD of

wastewater is produced from two paper machines, 13 batch digesters, two brownstock

washing lines, two evaporator trains, recovery and the bleach plant. Its (4 x 106 m3) aerated stabilization basin (ASB) contains four reactors with a total retention of 30-40 days. Samples were taken on five occasions in 1999, six in 2000, and once in 2002.

During 1999, the first reactor was not aerated. The second and third reactors housed six and twelve 40-hp aerators (30 kW) aerators, respectively. In early 2000, 1,200 hp (900 kW) of aeration was added to the first reactor and 360 hp (270 kW) was removed from the third; the samples collected in 2000 reflect this change. The ETS characteristics at

Mill A are listed in Table 3.1.

Table 3.1. Mill A effluent treatment system characteristics.

Reactor # Area (m2) Depth (m) Volume (m3) Total Power (hp) 1 1.963×106 1.067 2.094×106 0 2 7.085×105 1.22 8.644×105 240 3 5.384×105 1.13 6.084×105 480 4 3.805×105 1.22 4.642×105 0

Grab samples were collected from the inlet and outlet of the first reactor, the outlets of the second and third, and from the final effluent. Samples were collected on the first, third and fifth day, and then averaged. The sample locations, shown in Figure

3.1, are designated 1-in, 1-out, 2-out, 3-out, and final, respectively. Each sampling trip related to chronic toxicity assays lasted five days.

Reactor 1 Influent o 1-Out 1-In (from 1 treatment)

Reactor 2

2-Out Reactor 3

3-Out Reactor 4

Final Effluent

Reacto r 1

1-Out 1-In Influent

Rea ctor 2

2-Out Reactor 3 3-Out Reactor 4 Final Effluent

Figure 3.1. Secondary treatment system before (top) and after (bottom) changes in aeration.

Arrows indicate flow direction; the aerated zones are shaded. Samples were collected at 1-In, 1-Out, 2-Out, 3-Out, and Final Effluent locations.

Supplementary samples and data were analyzed from two additional mills to

determine the generality of the results. Mill B is also located in Southeastern US and

makes only bleached product from softwood. Samples were collected once in 2000. The

1.4 x 106 m3 lagoon receives 2,130 kW of tapered aeration and is curtained into three zones, with 67% of the aerators being located in the first zone. Samples were taken at the inlet and outlet of the treatment system, as well as at six locations across the system based on aeration power, i.e. 80% of the samples were collected from the first zone, with the remainder split between the second and third zones (see Figure 3.2).

Figure 3.2. ASB sampling locations for Mill B.

Mill C is located in New Augusta, MS, and makes bleached pulp. Its fiber line swings between hardwood and softwood production as described in Kemeny and

Banerjee92. It uses an activated sludge system (AST) with a retention time of 17 hours.

Eight samples were collected semiweekly in 1994. The data from this work are further analyzed in later sections.

The term “profile” refers to the change in concentration (or toxicity) across the treatment system, as measured at these sample locations. Temperature, pH, dissolved oxygen (DO), and conductivity were measured at the time of sample collection. Metals were measured at Mill A on six occasions. In addition, chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) were measured according to standard procedure93. Some of the samples were filtered through a

Whatman 934AH glass fiber filter to determine the total suspended solids (TSS)94. The difference between the filtered and unfiltered resin and fatty acid concentrations represents that amount which is bound to the TSS. From these data, the partitioning behavior of resin and fatty acids, both individually and collectively, can be determined.

The resin and fatty acids determined were abietic, dehydroabietic, neoabietic, pimaric, isopimaric, sandracopimaric, palustric, oleic, linoleic, palmitic and stearic acid, and are collectively designated as “RFA.” These samples were collected and stored in borosilicate glass bottles with Teflon®-lined caps at pH 10 and maintained at 4 oC until

92 Kemeny T.E. and Banerjee S. (1997) Relationships among effluent constituents in a bleached kraft pulp mill Water Res., 31, 1589-1594. 93 Clesceri, L.S., Eaton, A.D. and Greenberg, A.E. (1999) Standard Methods for Examination of Water & Wastewater. 20th ed., New York: American Public Health Association. 94 Clesceri, L.S., Eaton, A.D. and Greenberg, A.E. (1999) Standard Methods for Examination of Water & Wastewater. 20th ed., New York: American Public Health Association. 39

tested. Aqueous samples were extracted with diethyl ether, dried, concentrated, derivatized with TMAH and the RFA were quantified by gc-fid95.

Microtox® analyses were performed onsite following the whole effluent toxicity

(WET) protocol96, with a Microtox Model 500 Analyzer obtained from AZUR

Environmental. Microtox assays have been correlated to both acute and chronic

97,98,99 ® toxicity . Microtox toxicity results are reported as the EC50, or the effective sample concentration that causes a 50% reduction in light output.

The samples collected for the Ceriodaphnia dubia 7-day survival and reproduction bioassays100 were shipped to a contract laboratory. These samples were immediately cooled to approximately 0oC, shipped overnight on ice, and maintained below 4oC prior to testing. Law Engineering and Environmental Services (Kennesaw,

GA) conducted C. dubia assays according to standard EPA procedure101. However, the number of dilutions was extended to better resolve differences between samples.

95 National Council for Air and Stream Improvement (1989) Procedures for the analysis of resin and fatty acids in pulp mill effluents. Technical Bulletin No. 501. 96 Azur Environmental (1998) “Whole Effluent Toxicity Protocol” in MicrotoxOmni™ Software. 97 Ribo, J.M. and Kaiser, K.L.E. (1983) Effects of selected chemicals to photoluminescent bacteria and their correlations with acute and sublethal effects on other organisms. Chemosphere 12(11/12) Pages 1421-1442. 98 Sweet L.I., Travers, D.F., and Meier, P.G. (1997) Chronic toxicity evaluation of wastewater treatment plant effluents with bioluminescent bacteria: A comparison with invertebrates and fish. Environ. Toxicol. and Chem., 16(10) pages 2187–2189. 99 Firth, B.K. and Backman, C.J. (1990) Comparison of Microtox testing with rainbow trout (acute) and Ceriodaphnia (chronic) bioassays in mill wastewaters. Tappi J., 73(12), 169-174. 100 Horning W.B. and Weber C.I. (1985) Ceriodaphnia Survival and Reproduction Test Method 1002.0 in "Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms. EPA Technical Report No. EPA/600/4-85/014, 58-75. 101 Horning II, W.B. and Weber, C.I. "Ceriodaphnia Survival and Reproduction Test" Method 1002.0 in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 58-75. 40

Chronic toxicity (C. dubia) is presented as the lowest observable effective

concentration, or LOEC. The LOEC is the lowest concentration tested that statistically

differs from the control with respect to the average number of neonates reproduced per

organism.

The data were statistically analyzed to determine if there was a significant

difference (α = 0.05) between the means using the t-test for two means with unequal

variance. Furthermore, data variance between groups was tested for equality using the F-

test. First, the inlet and outlet from the entire ETS were tested. If a significant difference

existed, then further tests were performed between the inlet and outlet of each reactor. In

this way, the significance of changes across the ETS was assessed. In addition to

statistical relevance, the chemical or physical data profiles across the treatment system

were analyzed with respect to toxicity.

For example, while the change in reduced sulfur across the first reactor is

significant, its complete removal means that it cannot contribute to final effluent toxicity.

On the other hand, metals known to be toxic, such as strontium, may appear to decrease across treatment, though not at a statistically significant level. Therefore, potential contributors to final effluent toxicity can be screened out if they are not present in the final effluent or if concentration changes across treatment are not statistically significant.

Table 3.2 details the sample collection dates and testing matrix for the field studies undertaken in this research program. The table includes all of the sampling events

outlined in the Thesis Approach and will be referred to in the experimental sections for each of the four studies.

Table 3.2. Summary of sample collection dates and testing matrix.

Effluent Treatment System Pulp Mill Sewers Date TSS RFA COD Microtox Chronic DO Temp. pH Cond. BOD5 Flow Temp. pH RFA 5-7-99 * X X X X X X 9-2-99 ** X X X 12-6-99 † X X X X X X X X X 12-8-99 † X X X X X X X X X 12-10-99 † X X X X X X X X X 2-16-00 ‡ X X X 3-6-00 † X X X X X X X X X X X X X 3-8-00 † X X X X X X X X X X X X X 3-9-00 † X X X X X X X X X X X X X 10-23-00 • X X X X 11-7-00 †† X X 11-9-00 †† X X 11-11-00 †† X X 43 7-24-01 # X X X 7-26-01 # X X X 7-28-01 # X X X 7-6-01 • X X X X 6-10-02 # X X X X X X X X 6-27-02 • X X X X X X X X

* Mill A ETS sampling locations: 1o Clarifier In, Reactor 1 In, Reactor 1 Out, Reactor 2 Out, Reactor 3 location A, Reactor 3 location B, Reactor 3 location C, Reactor 3 Out, Final Effluent (see Figure 3.1) ** Mill A ETS sampling locations: 1o Clarifier In, Reactor 1 In, Reactor 1 Out, Reactor 2 location A, Reactor 2 location B, Reactor 2 location C, Reactor 2 location D, Reactor 2 Out, Reactor 3 Out, Final Effluent † Mill A ETS sampling locations: Reactor 1 In, Reactor 1 Out, Reactor 2 Out, Reactor 3 Out, Final Effluent ‡ Mill B ETS (see Figure 3.2) • Mill A †† Mill A ETS sampling locations: Final Effluent # Mill C ETS sampling locations: ETS Inlet, Final Effluent

3.4. Results and Discussion

Chlorinated analogs of some dehydroabietic and stearic acids were measured

entering the treatment system during an early screening trip. The concentration of

chlorinated resin and fatty acids was not quantifiable at the lower calibration limits of 0.1

ppm. As a reference point, dehydroabietic acid was quantified at 5 ppm in a sample of the influent to the secondary treatment system during the same screening. The mill provided unpublished NCASI data from an earlier date that confirmed only trace amounts of chlorinated resin acids were present below 0.1 ppm in the final effluent. Furthermore, the mill has increased chlorine substitution in the bleaching sequence since this time and this reduces chlorinated organics.

The NCASI data also indicated that no phenols were present at detectable limits, other than catechol, a hardwood lignin derivative, which was quantified just above the lower calibration limit of 2.0 parts per billion on three out of eleven occasions. Recalling the relationship presented in Equation 1-1 in Ch.1, the phenol concentration contribution to the toxicity index was weighted approximately an order of magnitude less than either fatty or resin acid concentration. The screening trip and NCASI data indicate that total resin acid concentration is at least three orders of magnitude greater than phenol concentration. As such, the contribution of phenol concentration to Equation 1-1 is negligible. Sterols were detected at concentrations on the order of 10 parts per billion.

Sterols are outside the scope of this project.

The first three sampling events, in May, September and December 1999, provide

a view of the operating conditions, and the chemical and toxicity profiles across the

secondary treatment system. Tables 3.3 and 3.4 summarize the operational ranges of

temperature, pH, dissolved oxygen, and other measures of general water quality in the

ETS influent and effluent of Mill A encountered over the course of this study.

Table 3.3. Operational ranges for Mill A ETS influent.

Measurement (units) Test Method102 Low High Temperature (oC) In field 30 37 pH In field 6.4 7.6 Dissolved oxygen (mg/L) SM 4500-O 0.1 2.4 Ammonia-nitrogen NH3-N (mg/L) SM 4500-NH3 1.7 15.8 Residual chlorine (mg/L) SM 4500-Cl < 0.06 < 0.06 Conductivity @ 25 oC (µmhos/cm) SM 2510 1460 2750 Total Hardness as CaCO3 (mg/L) EPA 130.2 190 255 Total Alkalinity as CaCO3 (mg/L) EPA 310.1 175 465 Chemical oxygen demand (mg/L) SM 5220 300 1,000 BOD5 (mg/L) SM 5210 85 160 Total suspended solids (mg/L) SM 2540 60 200

Table 3.4. Operational ranges for Mill A ETS final effluent.

Measurement (units) Test Method Low High Temperature (oC) In field 18 29 pH In field 7.2 7.8 Dissolved oxygen (mg/L) SM 4500-O 2.4 6.9 Ammonia-nitrogen NH3-N (mg/L) SM 4500-NH3 0.5 9.4 Residual chlorine (mg/L) SM 4500-Cl < 0.01 < 0.06 Conductivity @ 25 oC (µmhos/cm) SM 2510 1,400 3,000 Total Hardness as CaCO3 (mg/L) EPA 130.2 120 400 Total Alkalinity as CaCO3 (mg/L) EPA 310.1 210 465 Chemical oxygen demand (mg/L) SM 5220 130 700 BOD5 (mg/L) SM 5210 5 40 Total suspended solids (mg/L) SM 2540 8 45

102 All “SM” standard methods refer to: Clesceri, L.S., Eaton, A.D. and Greenberg, A.E. (1999) Standard Methods for Examination of Water & Wastewater. 20th ed., New York: American Public Health Association. 45

Table 3.5 details the same mills overall operating efficiencies, effluent flow rate, and mean residence time. Overall, the system tended to operate at the high end of the efficiency ranges. It should be noted that the December 1999 data were collected after a black liquor spill had occurred. Following a spill, the effluent coming from primary treatment first goes through an intermediary holding pond prior to entering secondary treatment. The purpose of this pond is to increase the residence time of the ETS and flatten out organic and inorganic spikes to the aerated stabilized basin.

Table 3.5. Overall ETS operating efficiencies and flow rates at Mill A.

Operating Parameter Low High Primary Clarifier TSS Efficiency (%) 35 80 COD removal efficiency – filtered (%) 20 65 COD removal efficiency – unfiltered (%) 34 58 BOD5 removal efficiency (%) 75 96 TSS removal efficiency (%) 48 93 Effluent flow rate (MGD) 29 42 Mean residence time (days) 30 40

COD profiles

COD is a common measurement of organic loading and the oxygen required to mineralize this material. Changes in COD are indicative of organics removal through biodegradation and sorption/settling. The results in Figure 3.3 indicate that the majority of the COD removal (85%) occurs across the first reactor. Biochemical oxygen demand followed a similar trend for the samples collected in March 2000. The COD and BOD5

profiles are in agreement with historical data103. The data indicate that there is little biological activity beyond the first reactor. Either the ETS operating parameters in the last three reactors are unfit to support biological activity, or the remaining organic matter is not readily biodegradable.

1200

900 2

O May-99 Sep-99 600 ppm , Dec-99 D

O Mar-00 C

300

0 Pond #1 In Pond #1 Out Pond #2 Out Pond #3 Out Final Effluent

Figure 3.3. Chemical oxygen demand profiles for samples collected from May 1999 through March 2000.

The statistical significance of the COD levels is summarized in Table 3.6. Each sample location was individually compared with every other sample location. Thus, 1- in:1-out compares the mean COD level of the ETS influent to reactor 1 to the effluent of reactor 1. First, the variances are compared using the F-test to determine which test should be used to compare the means of the two samples. As the variances were found to

103 Mahmood, T. and Banerjee, S. "Sources and fate of TRS compounds in a pulp mill ASB," in Water Science and Technology 40, no. 11: 289-295 (1999). 47

be equal for all samples, all of the mean comparisons were made using the student t-test

for means with equal variance. If the means are not statistically different (at the 5%

significance level), then it cannot be said that there is a significant change in the

measurement between the two sample locations. The results indicate that the only

significant change in COD occurs across the first reactor of the ETS.

Table 3.6. Statistical significance of COD levels across ETS (α = 0.05).

Testing between F-test for t-test for Samples: Equal Variances Equal Means 1-In and 1-Out Equal Statistical difference 1-In and 2-Out Equal Statistical difference 1-In and 3-Out Equal Statistical difference 1-In and Final Effluent Equal Statistical difference 1-Out and 2-Out Equal Not statistically different 1-Out and 3-Out Equal Not statistically different 1-Out and Final Equal Not statistically different 2-Out and 3-Out Equal Not statistically different 2-Out and Final Effluent Equal Not statistically different 3-Out and Final Effluent Equal Not statistically different

Toxicity profiles

In all experiments, the inlet to the secondary treatment system had a Microtox® whole effluent toxicity (WET) EC50 of less than 4%, as shown in Tables 3.7 and 3.8. This means that the 1-in sample must be diluted to less than 4% strength to prevent more than half of the bacteria to have their biological functions inhibited to the point that bioluminescence ceases. The data indicate that 100% strength effluents from reactor 3 and the final effluent from reactor 4 do not reduce bioluminescence by 50% or more.

That is, there is no EC50 associated with these samples, as measured by the Microtox®

WET protocol. Following the additional aeration added in 2000, the effluent from reactor

2 was no longer toxic based on Microtox®.

Table 3.7. Acute and chronic toxicity for December 6-10, 1999.

Sample Microtox® Microtox® C. dubia C. dubia LOEC Location % EC50 % effect (% Survival) (Reproduction) Reactor 1-In 3.4 100 0 10 Reactor 1-Out 0.06 99 100 10 Reactor 2-Out 86 55 100 50 Reactor 3-Out 100 40 100 25 Final Effluent 100 39 100 25

Table 3.8. Acute and chronic toxicity for March 6-9, 2000.

Sample Microtox® Microtox® C. dubia C. dubia LOEC Location % EC50 % effect (% Survival) (Reproduction) Reactor 1-In 2 100 60 20 Reactor 1-Out 40.0 61 100 40 Reactor 2-Out 100 46 90 50 Reactor 3-Out 100 32 100 30 Final Effluent 100 40 100 40

COD and toxicity profiles of filtered samples are provided in Figure 3.4 and show that the toxicity decreases just after the bulk of the COD is removed. It should be noted that increasing EC50 and LOEC concentrations indicate decreases in acute and chronic toxicity, respectively. The acute and chronic toxicity profiles correlate only to the extent that both decrease just after the first reactor for the December sampling and within the first reactor for the March episode, which benefited from increased aeration.

800 COD 720

ppm 640

560 Microtox 100 (%)

50 75

EC 50 C. dubia or 25

LOEC 0 1-in 1-out 2-out 3-out final 1000 900 COD 800 ppm 700 600

) Microtox 100 (%

50 75

EC 50 C. dubia or 25

LOEC 0 1-in 1-out 2-out 3-out final

Figure 3.4: COD and toxicity profiles across secondary treatment.

Samples collected in December 1999 (top) and March 2000 (bottom). EC50 and LOEC apply to the Microtox and C. dubia, respectively.

The level of aeration was increased before the March 2000 sampling, and this

leads to an earlier drop in COD as compared to the December result. The toxicity is also

reduced earlier in March, reflecting the removal of some of the toxicants. These results

confirm that many of the compounds that induce acute toxicity are treated. However, the

decrease in chronic toxicity is not as pronounced.

A comparison between COD removal and Microtox® toxicity removal (Figure

3.4) illustrates that the bulk organic removal and toxicity removal do not coincide. This is

not to say that individual carbon-based compounds are not being mineralized beyond the

first reactor. The fact that the bulk organic levels in reactors 2, 3, and 4 are not

statistically different does not preclude the potential for significant removal of some of

the hundreds of individual organic compounds. It is, however, outside the scope of this

project to quantify the changes of every compound entering the treatment system. As

such, the importance of the field studies lies in the isolation of toxicity and resin and fatty

acid profiles.

In particular, the C. dubia studies may offer some insight into the relationship

between RFAs and chronic toxicity. Similar to the COD profiles, there is little change in

chronic toxicity beyond reactor 2. However, the majority of the toxicity decrease occurs

in reactor 2 in December 1999 and to lesser extent in March 2000, while COD drops only

in reactor 1 for both dates.

RFA profiles

Entering the secondary treatment system, resin and fatty acids represent 80% and

20%, respectively. These percentages change to 60% and 40% in the final effluent. This indicates that fatty acids are more difficult to remove than resin acids. This result has been previously reported elsewhere104. On average, dehydroabietic acid accounts for approximately 25% of the total resin and fatty acids in the final effluent. DHA is one of the most recalcitrant resin acids in this ETS as shown in Figure 3.5. For this reason, DHA will be used as the model resin acid in future chapters.

Table 3.9 summarizes the average concentrations of RFAs and TSS across the primary and secondary treatment system over the duration of this research. Unfiltered samples represented the total resin and fatty acid concentrations both in solution and sorbed to suspended solids. The filtered samples represent the dissolved RFA fraction.

The difference between the filtered and unfiltered samples is the amount of RFA associated with the TSS.

Table 3.9 Average RFA and TSS concentration during effluent treatment.

Concentration Primary Reactor 1 Reactor 2 Reactor 3 Final (ppm) Clarifier Inlet Inlet Inlet Effluent Total RFA 14.8 6.6 3.0 2.0 2.1 Dissolved RFA 5.9 3.5 2.4 1.8 1.9 Sorbed RFA 8.9 3.1 0.6 0.2 0.2 TSS 160 93 26 15 11

104 Morck, R.; Jansson, M.B.; and Dahlman O. (2000) Resinous compounds in effluents from pulp mills in “Pitch Control, Wood resin and Deresination” (Back E.L. and Allen, L.H. Eds.), Tappi Press, Atlanta, GA. 52

5.0

4.0 m p p , Oleic Acid n 3.0 o i Linoleic Acid at r

t Palmitic Acid 2.0 Stearic Acid cen n o

C 1.0

0.0 0-in 1-in 1-out 2-out Final

5.0

4.0 m Abietic Acid p

p DHA , n 3.0 Neoabietic Acid o i

at Isopimaric Acid r t 2.0 Pimaric Acid

cen Palustric Acid n o Sandaracopimaric C 1.0

0.0 0-in 1-in 1-out 2-out Final

Figure 3.5. Average fatty and resin acid profiles across effluent treatment system.

Statistical analysis indicates that total RFA concentrations in the primary clarifier, reactor 1 inlet, reactor 2 inlet, and reactor 3 inlet are statistically different. However, the

differences between reactor 3 inlet, reactor 4 inlet (not shown) and the final effluent are not. The resulting solid:water partitioning coefficients for RFAs in the primary clarifier, first and second reactors range between 8,000 and 10,000 (unitless).

Table 3.10 summarizes the contribution of each reactor to the overall removal rate for total resin and fatty acids, the fraction dissolved, the fraction sorbed and total suspended solids

Table 3.10 Average RFA and TSS removal contributions to overall removal rate.

Removal Rate Primary Reactor 1 Reactor 2 Reactors Total Clarifier 3 and 4 Removal Total RFA 55% 24% 7% 0% 86% Dissolved RFA 41% 19% 10% 0% 68% Sorbed RFA 65% 28% 4% 0% 98% TSS 42% 42% 7% 3% 93%

From these tables it is clear that most of the total resin and fatty acid removal occurs between the primary clarifier influent and the outfall of the first reactor. The drop in dissolved RFA concentration from the primary clarifier to secondary treatment may be the result of a significant decrease in system temperature. As temperature decreases, resin acid solubility decreases causing increased partitioning of RFA to TSS. Of the resin and fatty acids entering the secondary treatment system, roughly 68% were removed during this study. Approximately 47% of the RFAs entering secondary treatment are sorbed to

TSS, compared to less than 10% in the final effluent. The bulk of the RFA removal from secondary treatment is due to the removal of TSS. About 45% of the dissolved RFAs are

removed during secondary treatment, while nearly 94% of the bound RFAs entering

treatment are removed. This indicates that it may be more effective to remove RFA

bound to suspended solids in other wastewater streams.

Figure 3.6 compares the changes in TSS and the unfiltered (solid) and filtered

(open) RFA for the samples collected in December 1999 and March 2000. As the TSS is

removed, the unfiltered RFA decreases and the filtered RFA remains essentially constant

after the second reactor. The unfiltered sample is a measure of the total RFA, whereas

the filtered sample is only the RFA that is in the water column. The difference between

these samples is the RFA associated with the TSS.

160

0 )

m 20 p p

( Mar 00 n

o 10 i t a r t 0 en

nc 20 o Dec 99 C 10

1-In 1-Out 2-Out 3-Out Final

Figure 3.6. Total suspend solids (triangles), unfiltered (solid diamond) and filtered (open) resin acid concentrations.

The long hydraulic residence time associated with the Mill A ETS makes the concentration profiles difficult to interpret, since the input is not necessarily constant.

The concentration of a compound at a given location reflects not just the various degradative and dissipative pathways, but also a varying input load. Figure 3.6 compares filtered and unfiltered RFA concentrations. The difference is linear with TSS, as shown in Figure 3.7, which confirms that the insoluble RFA is bound to TSS.

6 ) m p p

( 4 A RF ⎠ 2

0 0 20406080100 TSS (ppm)

Figure 3.7: Relationship between bound RFA and TSS.

As expected, the TSS decreases progressively across the treatment system,

averaging 85% removal over the course of the study. Hence, settling must be a removal

mechanism for the RFAs bound to the TSS. The Figure 3.7 plot only includes values

between 1-in and 2-out, since the TSS is low beyond that point and the differences in

RFA are small. Biodegradation may, of course, occur after settling, but this is outside the scope of this study.

The inlet sample was taken from the inflow to the treatment system and the solids are mainly wood fiber. Consider the solids:water distribution at locations 1-out and 2-out

in Figure 3.6. Values for the (dimensionless) fiber:water distribution coefficient, Kd, were identical at the two locations at 7,000 for the December 1999 samples; the corresponding values for March 2000 were 15,200 and 15,600 respectively. If only resin acids are considered, the 1-out value for the December sampling was 6,500. Recall that the

December samples were collected following a black liquor spill. Spills increase both pH and conductivity in the wastewater, both of which decrease fiber:water partitioning. The partitioning of resin acids between inactivated aerobic biomass and water follows a linear

105 isotherm , with a much lower Kd of 300-1,100. Consequently, these values are far too high to reflect simple partitioning to biomass.

105 Hall E.R. and Liver S.F. (1996) Interaction of resin acids with aerobic and anaerobic biomass – II. Partitioning on biosolids. Wat. Res. 30(3), 672-678.

Hydrophobic compounds sorb strongly to the lignin in pulp fiber and fines106,107, and it is likely that the resin acids are principally bound to fiber and fiber-derived fines rather than to microbial biomass at 1-out. The fibers progressively settle out, and the resin acids in the unfiltered and filtered samples eventually converge. This is not to minimize the importance of sorption to biomass. However, if fiber constitutes a significant fraction of the initial TSS, then the resin acids will substantially associate to and settle out with the fiber.

To further identify the nature of the hydrophobic solids present, experiments were carried out to determine the Kappa number, η, of the pulp-derived solids exiting the primary treatment system and in the pulp mill sewer. DRIFTS IR spectra of the TSS were used to determine the lignin content of the fibers. The procedure is described in detail elsewhere108. A bleached fiber filter pad was used for background subtraction. TSS

samples were mounted on silicon carbide discs for support and scanned at least 30 times.

From the resulting spectra, the Kappa number of the fibers entering the treatment system

was determined to be approximately 70. This is consistent with the unbleached Kappa

number of the brown fiber processed at Mill A.

106 Severtson, S.J. and Banerjee S. (1996). Sorption of chlorophenols to wood pulp. Environ. Sci. Technol. 30, 1961- 1969. 107 Severtson, S.J. and Banerjee S. (2001). Dual reactive domain model for sorption of aqueous organics by wood fiber, J. Colloid Interfacial Sci., in press. 108 Friese, M.A. and Banerjee, S. (1992). Lignin determination by FT-IR. Applied Spectroscopy 46 (2), 246-248. 58

Severtson109 found that the fiber:water partitioning coefficient for hydrophobic,

weak acids could be estimated from:

o Kd ≈ 0.0015*α*η*Kl (3-1)

o where α is the fraction of acid dissociated, η the fiber Kappa number, and Kl the

o lignin:water partitioning coefficient. The terms α and Kl can be estimated from:

α = 1/(1+10^(pH-pKa)) (3-2)

o Kl = 10^(0.95*logKow - 0.48) (3-3)

Using a Kappa number of 70, pH 7.0 and the logKow and pKa data in Table 3.11, the fiber:water partitioning coefficients for dehydroabietic acid and abietic acid are estimated to be 2,600 and 9,600, respectively. Similarly, Kd for oleic acid, a fatty acid, is

7,600. The differences in chemical structure (illustrated in Figure 1.1) account for the

difference in pKa and ultimately the octanol:water partitioning coefficient at neutral pH.

Table 3.11. Physicochemical properties for model resin and fatty acids110,111.

Dehydroabietic acid Abietic acid Oleic acid log Kow 6.5 6.5 7.7 pKa 5.7 6.4 5.0

109 Severtson, S.J. and Banerjee, S. Sorption of chlorophenols to wood pulp. Environ. Sci. Technol. 30 (1996), pp.1961- 1969. 110 Nyren, V. and Back, E. "The Ionization Constant, Solubility Product and Solubility of Abietic and Dehydroabietic Acid" in Acta chemica Scandinavica, 12(7), (1958), pp. 1516-1520. 111 logKow estimated using Syracuse Research Corporation’s KowWin program as described in: Meylan, W.M. and Howard, P.H. Atom/fragment contribution method for estimating octanol-water partition coefficients. J. Pharm. Sci. 84 (1995), pp. 83-92. 59

It should be noted that since these acids are rather weak, a small change in system

pH will have a large effect on the solids:water partitioning coefficients. For example, the

Kd for dehydroabietic acid more than doubles to over 7,400 as pH drops from 7.0 to 6.5.

Similarly, the partitioning coefficients for abietic acid and oleic acid increase to over

21,000 and 23,000, respectively, for the same change in pH conditions.

Figure 3.8 demonstrates the relationship between DHA (open diamonds) and the total RFA (solid diamonds) in the treatment system. In general, DHA is removed to a lesser extent than the other main RFA constituents, such as abietic and oleic acid. The relationship between DHA and toxicity was further examined, since DHA represents a significant fraction of the RFA remaining in the final effluent.

20 Mar 00

0 20 Dec 99 )

m 10 p (p 0 ion t 8 Sep 99 tra n e

nc 4

Co 0 8 May 99

0 1-In 1-Out 2-Out 3-Out Final

Figure 3.8. Total unfiltered RFA (solid) and DHA (open) profiles collected at various periods.

The acute and chronic toxicity is most effectively reduced across the second

reactor, as shown in Figure 3.9. The left and right plots are for the samples collected in

December 1999 and March 2000, respectively. The toxicity profile was not observed to follow the COD profile. Most of the COD is removed in the first reactor, whereas toxicity decreases significantly after the second reactor. The change in concentration of DHA across treatment is also shown in Figure 3.9. The solid squares represent the unfiltered (or total) DHA and the open squares represent the filtered DHA concentration. The

difference between the filtered and unfiltered concentrations is the DHA associated with

TSS.

% 100 100 , , % Microtox Microtox 0 0 75 5 75 EC EC5 C. dubia C. dubia r r 50 50 o

25 C 25 E 0 0 LO LOEC o ) ) 5 10 m m p p . (pp nc. ( nc 5 o c

DHA co 0 DHA 0 1-In 1-Out 2-Out 3-Out Final 1-In 1-Out 2-Out 3-Out Final

Figure 3.9. Acute and chronic toxicity profiles and unfiltered (solid) and filtered (open) DHA concentration profiles for December 1999 (left). and March 2000 (right).

These figures qualitatively indicate that DHA contribute to chronic toxicity in the

ETS. Particularly, the filtered DHA change in concentration appears to correlate with the change in chronic toxicity. The filtered DHA represents the fraction not bound to TSS and most likely to be bioavailable to Ceriodaphnia. The qualitative findings will be confirmed in laboratory dose-response studies in the next chapter.

The unfiltered DHA profiles for the four sampling episodes are shown in Figure

3.10. With the exception of the December 1999 samples, the DHA concentration in the final effluent is typically about 1 ppm. The December 1999 data coincide with a recent black liquor spill at the mill. 62

10.00

8.00 ) m

6.00

n (pp May-99 o Sep-99 ati

tr Dec-99 n 4.00 Mar-00 Conce

2.00

0.00 Pond #1 In Pond #1 Out Pond #2 Out Pond #3 Out Final Effluent

Figure 3.10. Unfiltered Dehydroabietic acid profiles for samples collected from May 1999 through March 2000.

An important consequence of this is that process upsets can shock-load treatment systems with recalcitrant, toxic substances such as DHA. Therefore, it is important to understand the relationship between process conditions and partitioning behavior of environmentally important chemicals. The toxicity of resin acids is inversely related to pH due to the presence of ionizable carboxylic acid groups112,113. As pH increases, resin acids become more soluble and toxicity decreases. The hydrophobicity of resin acids, as estimated by the octanol-water partitioning coefficient, is also a function of pH for the same reason. Thus, the combination of system pH and the dissociation constants of resin acids will affect solubility, hydrophobicity, partitioning and toxicity.

112 Zanella, E. "Effect of pH on Acute Toxicity of Dehydroabietic Acid and Chlorinated Dehydroabietic Acid to Fish and Daphnia," in Bull. Environm. Contam. Toxicol. 30, 133-140 (1980). 113 McLeay, D.J., Walden, C.C. and Munro, J.R. "Influence of Dilution Water on the Toxicity of Kraft Pulp and Paper Mill Effluent, Including Mechanisms of Effect," in Water Research 13, 151-158 (1979). 63

It has been proposed that only soluble resin and fatty acids should be bioavailable and predominantly responsible for toxicity. As such, the filtered RFA fraction is related to toxicity index in Figure 3.11. Toxicity index is defined as:

Toxicity index = (100 – NOEC)/100 (3-4)

where NOEC is the “no observable effect concentration” for C. dubia reproduction.

Presented in this way, an increase in toxicity index represents an increase in chronic toxicity. The index ranges from 0 to 1. Figure 3.11 illustrates a linear relationship between total filtered RFA and toxicity. Roughly 60% of the variance in chronic toxicity for this full-scale effluent treatment system is due to dissolved resin and fatty acid concentration. It should be recalled that DHA was the predominant resin acid quantified for these samples.

1.2

1 x

e 0.8 d n 0.6 ty I

i y = 0.03x + 0.55 c 2 xi 0.4 R = 0.60 o T 0.2

0 0.00 5.00 10.00 15.00 20.00 Total Filtered RFA, ppm

Figure 3.11. Relationship between total filtered resin and fatty acids and toxicity index.

These results indicate that resin acids, specifically dehydroabietic acid, are responsible for a significant portion of the residual toxicity in the final effluent.

Furthermore, residual toxicity may be expected to increase when increased resin acid concentrations are experienced (i.e. during a spill). This also suggests that any reduction in effluent volume without a concurrent reduction in resin acid concentration may result in episodes of increased toxicity.

Profiles of DHA, RFA, and COD (all filtered) collected on two occasions are presented in Figure 3.12. The March results are unexceptional; all three constituents decrease in Reactor 1. The December results, however, show a DHA/RFA spike at the outfall of Reactor 1. This originates from an earlier spill as confirmed by the mill.

800 750 COD 700 ppm 650 600

16 12 RFA 8 ppm 4 DHA 0 1-in 1-out 2-out 3-out final 1000

900 COD

ppm 800

700

16 12 RFA 8 ppm 4 DHA 0 1-in 1-out 2-out 3-out final

Figure 3.12: COD, RFA, and DHA profiles for samples collected in December 1999 (top) and March 2000 (bottom).

The mill uses a spill holding pond to increase the mean residence time in the

treatment system following spills. The COD decreases smoothly and the profile

resembles those collected on other occasions in 1999 (Fig 3.3). The resin acids were high

at 1-out, whereas the COD was normal, which indicates that the RFAs are recalcitrant

relative to COD. Therefore, the COD and RFAs must be removed through different

mechanisms, at least in a spill situation. Since RFAs are among the more recalcitrant

COD constituents, they are not degraded as rapidly and appear as a broad pulse. Werker

and Hall suggested this possibility earlier114,115, and found in laboratory-scale work that microorganisms acclimated to resin acids were unable to degrade a shock load because of a long lag period. Hence, if a spike clears the front end of the lagoon where biological activity is most intense, it could travel through the system relatively unaffected. Figure

3.12 provides full-scale confirmation of Werker and Hall’s laboratory findings.

Roughly similar results were obtained for Mill B and are compared to those from

Mill A in Table 3.12. A direct comparison of samples taken within the lagoon across the

two mills is difficult, since the geometry and mixing characteristics are very different.

Hence, only the influent and effluent results are considered. Although the influent values

were higher (on average) than those of Mill A, the final effluent concentrations were

similar during high loading situations. As with Mill A, the DHA/RFA ratio increased

114 Werker A.G. and Hall E.R. (1999) Limitations for biological removal of resin acids from pulp mill effluent. Wat. Sci. Tech. 40(11,12), 281-288. 115 Werker A.G. and Hall E.R. (2000) The fate of a resin acid shock load in a biological system. Pulp and Paper Canada 101 (1), 45-49. 67

from influent (0.21) to effluent (0.34), confirming the relative recalcitrance of DHA. A

similar recalcitrance has been reported in a full-scale study116.

Table 3.12. Comparison of DHA and RFA levels (ppm) across Mills A and B.

DHAin DHAout RFAin RFAout Mill A* 1.0 0.5 6.6 2.1 Mill B 8.0 2.4 39 7.1 *Averaged over 14 sampling episodes

Mill C alternated between softwood and hardwood production; the RFAs in the

influent changed concomitantly. Over the eight sampling occasions, the unfiltered DHA

and RFA influent concentrations were 4 ± 2 and 30 ± 20 ppm, respectively; the

corresponding effluent values were 0.2 ± 0.2 and 1 ± 1 ppm, respectively. The relatively

high uncertainty results from the fiber line swing between hardwood and softwood. As

before, the DHA/RFA ratio increased from the influent to the effluent, in this case, from

0.13 to 0.19. DHA decreases by 95% across the treatment system, as compared to 50 and

70% for Mills A and B, respectively. Although possible, it is unlikely that this increase is

entirely due to improved biological action, since the efficiencies of ASTs and ASBs are

similar for other constituents117. The suspended solids levels in an AST are much higher than those in an ASB, and sorption and settling is expected to play a larger role in an

116 Zender J.A., Stuthridge T.R., Langdon A.G., Wilkins A.L., Mackie K.L. and MacFarlane P.N. (1994) Removal and transformation of resin acids during secondary treatment at a New Zealand bleached kraft pulp and paper mill. Wat. Sci. Tech., 29(5,6), 105-121. 117 Kemeny, T.E. and Banerjee, S. "Correlations Among Contaminant Profiles in Mill Process Streams and Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 151-158. 68

AST. These results are consistent with the results of an earlier field study118 where the degradation of radio labeled oleic acid in an AST and an ASB was compared. Sorption was found to play a more important role for the AST, which suggests that resin acid toxicity should be lower in an AST.

The main conclusion is that DHA can be responsible for a significant fraction of the chronic effluent toxicity in ASBs. Its presence in the effluent of an AST should be smaller. It is only partially removed biologically, and association with fiber or biomass and subsequent settling represents an important removal pathway. If an RFA spill is large enough to traverse the front end of an ASB, which is the region of highest biological activity, then the spike can move through the lagoon since both biological activity and the TSS level will progressively decrease through the treatment system. The spike will broaden as it moves due to mixing in the lagoon and could elevate effluent toxicity until it washes out.

3.5. Section Summary

Profiles of resin and fatty acids (RFAs), COD, and aquatic toxicity were measured across the secondary treatment systems of three pulp mills. Most of the reductions in organic loading occurred by the outfall of the first reactor. Resin and fatty acids, specifically DHA, are some of the most recalcitrant organic materials in the secondary treatment system. The majority of the toxicity removal occurred across the first two

118 Williams C.L., Mahmood T., Corcoran H., Zaltzmann, M.E. and Banerjee S. (1997) In-situ measurement of local biodegradation during secondary treatment. Application to bleached pulp mill chloro-organics. Environ. Sci. Technol., 31, 3288-3292. 69

reactors, and the same trend was observed for the resin and fatty acids. The addition of aeration to the first reactor (Figure 3.1), prior to March 2000 sampling, had the effect of reducing the toxicity earlier in treatment. The third and fourth reactors are effective as additional treatment volume during periods of increased loading.

The RFAs sorb to suspended solids, principally fiber, and are partially removed through settling. RFA sorption to solids represents a significant removal pathway, as removal of TSS accounts for 63% of the RFA removal. An activated sludge system was more efficient in removing RFAs than was the aerated stabilization basin (ASB) because of its higher solids level. Dehydroabietic acid may account for a significant fraction of the effluent toxicity in the two ASBs studied. Analysis prior to a black liquor spill confirmed that although secondary treatments systems may be responsive to COD spikes,

RFA spikes are not removed as quickly. The microorganisms in an ASB are unable to respond rapidly to an RFA spill, and effluent toxicity can be elevated for a prolonged period because of hydraulic mixing.

The prior experiments were carried out in order to answer the first and second dissertation questions, namely, will reductions in resin and fatty acid concentration result in acute and chronic toxicity decreases across the ETS. However, the results present do not unconditionally prove this relationship. The next section aims to prove the relationship between reduction of a model resin acid and reductions in acute and chronic toxicity in real mill effluents.

70 4. DHA Acute and Chronic Toxicity in Treatment System Effluents

4.1. Section Overview

This chapter demonstrates the relationship between dehydroabietic acid and final effluent toxicity, as measured by the Microtox® whole effluent toxicity test and the

Ceriodaphnia dubia seven-day, static renewal survival and reproduction test. Resin acids in general, and dehydroabietic acid (DHA) specifically, have been consistently found in pulp mill secondary treatment system final effluents and linked to acute toxicity

1,2,3,45 outbreaks . Previous research has determined the LC50 (96-hr, rainbow trout) for acute toxicity, and IC25 (reproduction, Ceriodaphnia affinis) for the chronic toxicity thresholds for DHA as 0.8-1.7 mg/L6 and 6.6 mg/L7, respectively.

However, these values are not absolute, but specific to the organism, test conditions and test matrix. For example, pH has been shown not only to have a strong effect on the toxicity of pulp mill effluents8, and specifically DHA9, but also on the

1 Munoz M.J., Castano A., Blazquez T., Vega M., Carbonell G., Ortiz J.A., Carballo M., and Tarazona J.V. (1994) Toxicity identification evaluations for the investigation of fish kills: a case study. Chemosphere 29(1), 55-61. 2 Hutchins F.E. (1979) Toxicity of pulp and paper mill effluent: a literature review. U.S. EPA Report EPA-600/3-79- 013. 3 Carlberg G.E (1993) Characterization of effluents from mechanical pulp production. EUCEPA International Environmental Symposium Proceedings, 45-52. 4 Walden C.C. and Howard T.E. (1981) Toxicity of pulp and paper mill effluent: a review. Pulp Paper Can 83, T143- 148. 5 Liss S.M. and Allen D.G. (1992) Microbiological study of a bleached kraft pulp mill aerated lagoon. J Pulp Paper Sci, 18, J216-221. 6 Liss S.M., Bicho P.A. and Saddler J.N. (1997) Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview. Can. J. Microbiol., 75, 599-611. 7 O’Connor, B.I.; Kovacs, T.G.; and Voss, R.H. (1992) The effect of wood species composition on the toxicity of simulated mechanical pulping effluents. Environ. Toxicol. Chem. 11 1259-1270. 8 McLeay D.J., Walden C.C., and Munro J.R. (1979) Effect of pH on toxicity of kraft pulp and paper mill effluent to salmonid fish in fresh and seawater. Wat Res 13, 249-254. 9 Zanella, E. (1983) Effect of pH on acute toxicity of dehydroabietic acid and chlorinated dehydroabietic acid to fish and Daphnia. Bull. Environm. Contam. Toxicol. 30, 133-140. 71 ability of biomass to mineralize DHA10. As demonstrated in the previous chapter, the presence of other toxicants and dissolved, colloidal and suspended solids complicates the situation, as has been reported previously for DHA11. The data in Figure 3.9 illustrate that it is possible to have DHA concentrations below the published IC25 threshold, but still exhibit a similar inhibitory response. Thus, knowing the toxicity of DHA in a binary aqueous system is not enough to predict the toxic threshold of DHA in real pulp mill

effluents.

It would be more instructive for Kraft mills to understand the toxic threshold of

DHA in a representative aqueous matrix. Since different test organisms respond

differently to the same toxicant concentration, pulp mills should be most interested in

bioassays that are directly used in discharge permits, or ones that are rapid, inexpensive,

reproducible and highly correlated to the bioassays used in permitting. In this chapter

both types of assays were employed. The Ceriodaphnia survival and reproduction test,

EPA Method 1002.0, is commonly used in the National Pollutant Discharge Elimination

System (NPDES) permit requirements12. Forty-five out of the fifty U.S. states have EPA-

approved NPDES permitting programs13. All of the mills used in this study reside in

states with NPDES programs with conditional monitoring of chronic toxicity for

Ceriodaphnia dubia using the 7-day static renewal test with either NOEC, IC25 or percent

10 Yu Z. and Mohn, W.W. (2002) Bioaugmentation with the resin acid-degrading bacterium Zooglea resiniphila DhA- 35 to counteract pH stress in an aerated lagoon treating pulp and paper mill effluent. Water Research 36(11), 2793- 2801. 11 Kukkonen J. and Oikari A. (1987) Effect of aquatic humus on accumulation and acute toxicity of some organic micropollutants. Sci. Total Environ. 62, 399-402. 12 Horning II, W.B. and Weber, C.I. "Ceriodaphnia Survival and Reproduction Test" Method 1002.0 in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 58-75. 13 U.S. EPA website: http://cfpub.epa.gov/npdes/index.cfm, accessed on May 1, 2003. 72 effect reporting formats14. As noted, the Microtox® method15 exhibits good correlation with the acute assay using Rainbow trout (Oncorhynchus mykiss)16.

As such, DHA dose-response curves were generated for both acute and chronic

toxicity protocols in real mill effluents. Laboratory studies of a simulated dehydroabietic

acid spike in final effluent at pH 8 resulted in acute and chronic EC50s of 3.7 and 2.0 ppm

DHA, respectively. The applicability of these laboratory studies to the prior field

situations is assessed.

4.2. Experimental Approach

The results from the previous chapter indicate that resin acids are significant

contributors to final effluent chronic toxicity. Thus, bioassays used to study the toxicity

of resin acids in matrices other than real mill effluents provide only a starting point for

recommending threshold concentrations. Using real mill effluents as the testing matrix

offers additional information, namely the effect of other toxicants and dissolved solids. A

drawback to this approach is that the results are specific to systems similar to the ones

studied. As such, two mill effluents were used in these experiments to increase the

general value of the results. While not universal, the results should indicate whether the

test organisms are more or less sensitive to dehydroabietic acid in a representative matrix

compared to deionized water. As little suspended solids are present in the final effluent,

TSS was removed to simplify the system. The presence of TSS in the effluent could act

14 U.S. EPA website: http://oaspub.epa.gov/enviro/ef_home2.water, accessed on June 15, 2003. 15 Azur Environmental (1998) “Whole Effluent Toxicity Protocol” in MicrotoxOmni™ Software. 16 Firth, B.K. and Backman, C.J. (1990) Comparison of Microtox testing with rainbow trout (acute) and Ceriodaphnia (chronic) bioassays in mill wastewaters. Tappi J., 73(12), 169-174. 73 as a resin acid “reservoir” due to strong partitioning to hydrophobic solids. These resin

acids may re-equilibrate following mixing with receiving waters, which typically have

dilution factors around 100. Long-term implications of RFA sorption and settling in the

treatment system include the release of these compounds to receiving waters following changes in ASB reactor levels (depth), transience in production and sludge dredging.

4.3. Experimental

Microtox® bioassays

Laboratory studies were performed to establish the relationship between DHA and

Microtox® acute toxicity in the wastewater matrix. Final effluent was collected from Mill

A in December 1999 and March 2000. Filtered, treated final effluent (test matrix) was spiked with 25 ppm DHA and 2:1 serial dilutions were made at pH 8. Prior research has indicated the solubility of DHA in real mill effluents to greater than 40 ppm at pH 817.

The test was done in triplicate using the whole effluent toxicity (WET) protocol18.

Approximately 50 ml of test matrix was adjusted to 2% NaCl with Microtox® osmotic adjusting solution (Azur part # 686019). The frozen bioluminescent bacteria

(Microtox® reagent, Azur part # 686017) stock was reconstituted according to procedure

by adding 1ml of nontoxic water to a bottle of reagent. Mixing was achieved by

aspirating and dispensing approximately 0.5 ml of solution in the cuvette 20 times.

17 Werker A.G. and Hall E.R. (1997) The influence of pH on resin acid solubility related to biodegradation kinetics of resin acid in pulp mill effluent. 1997 Environmental Conference & Exhibit Proceedings, 19-26. 18 Azur Environmental (1998) “Whole Effluent Toxicity Protocol” in MicrotoxOmni™ Software. 74 Test cuvettes were prepared by adding 0.5 ml of Microtox® dilutent (Azur part #

686011) to 10 µl of reconstituted bacteria. Samples were transferred to the disposable glass cuvettes using a micropipette with disposable tips. Other test cuvettes were prepared by adding 1.5 ml of dilutent to each cuvette, except for the first cuvette. Next,

3.0 ml of the osmotically adjusted test matrix was added to the first cuvette. Serial dilutions (2:1) were then made by pipetting 1.5 ml from the first cuvette into the second, mixing, and transferring 1.5 ml to the next cuvette and so on, thereby developing the volumetric concentrations shown in Table 4.1 as dilution number 1-6. Deionized water blanks (B) and full-strength final effluent (FE) samples (without the DHA spike) were also tested to identify background toxicity contributions.

Table 4.1. Volumetric concentrations used in Microtox® dose-response experiments.

Dilution Volumetric DHA concentration Number concentration (%) (ppm) 1 100 25 2 50 12.5 3 25 6.2 4 12.5 3.1 5 6.2 1.5 6 3.1 0.8 B 0 0 FE 100 0

Following temperature equilibration (5.5 oC for the bacteria, 15 oC for the test samples), the test begins with the transfer and mixing 10 µl of the reconstituted reagent to the cuvettes containing the serial dilutions of the test matrix. The percent acute effect was determined as the reduction in light output of each sample with respect to the light output

75 of the full strength, unspiked test matrix. Responses were measured after 5, 15 and 30

minutes. Microtox toxicity results are reported as the EC50 and the percent effect at full

strength (percent effect). The EC50 is the effective sample concentration that causes a

50% reduction in light output. The percent effect is the percentage of light output

reduction at full (100%) sample strength.

Ceriodaphnia dubia bioassays

Similar dose-response experiments were conducted to determine the chronic

toxicity of DHA in real mill effluents, according to the Ceriodaphnia dubia 7 day, static

renewal, survival and reproduction assay. Final effluent samples were collected over two

7-day periods in November 2000 and July 2001 at Mill A and Mill C, respectively. The

descriptions of these mills can be found in Ch. 3. Chronic toxicity testing was performed

on final effluent samples split into two groups. The first involved running the toxicity test

on the effluent as received and the second involved dosing the effluent with DHA.

Additionally, two laboratory controls were conducted, using deionized water and

deionized water with a DHA spike.

The C. dubia test measures the acute effects (if any) by tracking the survival of the female organisms throughout the duration of the bioassay. It also tests subacute effects by tracking the number of neonates reproduced per surviving female. The test is terminated when 60% or more of the surviving control females have produced their third brood, or at the end of eight days, whichever occurs first. These criteria may be met at

76 six, seven, or eight days19. The test conditions, laboratory accreditation, raw data and detailed results can be found in Appendix A.1. Table 4.2 summarizes the key test conditions.

Table 4.2. Test conditions for DHA chronic toxicity dose-response experiments.

Volumetric concentrations tested 100, 75, 50, 25, 10, 1% and controls Deviation from test protocol None Temperature 24.0-26.5 oC Photoperiod 16 hrs light, 8 hrs darkness Renewal of test concentrations Daily Test solution volume 15 ml Test chamber volume 30 ml Age of test organisms Newly hatched neonates, < 24 hrs old No. of neonates per test chamber 1 No. of replicate champers per concentration 10 No. of neonates per concentration 10 Aeration none Sample volume required 1.0 L per day Sampling requirement Collected daily, used within 36 hrs

Chronic toxicity is presented as the no observable effect concentration (NOEC),

the lowest observable effective concentration (LOEC), and the EC50. The NOEC is the

highest concentration tested that does not statistically differ from the control with respect

to the average number of neonates reproduced per organism. The LOEC is the lowest

concentration that does statistically differ from the control. The EC50 is defined as the sample concentration that exhibits a 50% reduction in reproduction, as measured by the average number of neonates in a brood.

19 Horning II, W.B. and Weber, C.I. "Ceriodaphnia Survival and Reproduction Test" Method 1002.0 in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, (1985), pp. 58-75. 77

Samples before and after toxicity testing were analyzed for RFA concentrations,

as described in Ch. 3. RFA sampling and DHA spiking of the final effluent was carried

out as follows.

The spiking solution was constantly mixed on a magnetic stirrer for the duration

of the study. Upon receipt of the samples, they were divided into two, one to be "spiked"

and one to be used as the "baseline". The samples were allowed to reach room

temperature (overnight where possible) while mixing with a magnetic stirrer. At this

point, temperature and pH were measured. A 250 ml aliquot of the "baseline" sample was

collected in glass bottle, labeled, and adjusted to pH 10 using 6M NaOH or equivalent.

This sample was analyzed for RFA. Next, 3.5 ml of spiking solution (aqueous, ~ pH 9.5)

was added to one liter of sample and allowed to mix for 60 minutes. Once again,

temperature and pH were measured. Another 250 ml aliquot of "spiked" sample was

collected in glass bottle, labeled, and adjusted to pH 10 for RFA analysis. All samples

analyzed for RFA analysis were handled and tested according to standard procedure20.

4.4. Results and Discussion

Microtox® dose-response experiments

The Microtox® dose-response curve for DHA is illustrated in Figure 4.1 The

shape of the curve is typical of the appropriate concentration range for conducting such a

20 National Council for Air and Stream Improvement. (1989) Procedures for the analysis of resin and fatty acids in pulp mill effluents. Technical Bulletin No. 501. 78 test. At the upper end of the concentration range, a 100% effect was observed, while at

the lower end of the range, very little toxicity was associated with the sample.

100%

75% ect f f

e E 50% t Acu 25%

0% 0 5 10 15 20 25 DHA Concentration (ppm)

Figure 4.1. Dose-response curve for DHA spike in final effluent using Microtox® WETprotocol.

Table 4.3 shows the results of the dose-response experiments using the Microtox®

WET test protocol. Experiments were run with endpoints at 5, 15 and 30 minutes, according to procedure, though the results are not statistically different.

Table 4.3. Results of the Microtox® dose-response experiments.

% EC50 EC50 (ppm % Effect at full strength DHA) 5 min 14.8 3.7 100% 15 min 13.9 3.5 100% 30 min 13.1 3.3 100%

The key finding is the Microtox EC50 of DHA-spiked final effluent (Mill A) was

3.7 ppm, with a 95% confidence interval of 3.0 to 4.1 ppm. Additionally, these

experiments illustrate the effect of a DHA spike introduced into the final effluent. As the

field results illustrated in Ch. 3, the effluent treatment system (ETS) of Mill A was

effective in handling the bulk COD load associated with a black liquor spill, but was not

able to handle the increased RFA loading that came with it. Figure 4.1 shows that a spill resulting in a DHA spike to the order of 10 ppm will have a greater than 75% acutely toxic effect, as measured by the Microtox® WET test method. This is without the

confounding effect of a spike in other resin and fatty acids or other toxicants.

It is worth mentioning that the DHA concentration range in the final effluent was

often near the EC50 range determined experimentally. This highlights the importance of

effectively removing DHA from the pulp mill wastewater system. This has important

implications for Mill A, as the ETS inlet is typically about 6-10 ppm resin acids (~2 ppm

DHA) and the final effluent contains about 1 ppm DHA.

The correlation between DHA concentration and acute toxicity for the March

2000 samples is illustrated in Figure 4.2.

80 100

R2 = 0.9542 (linear fit) 75 ct ffe e E

t 50 u c A %

0 0.00 0.25 0.50 0.75 log DHA concentration (ppm)

Figure 4.2. Correlation between DHA concentration and Microtox® acute toxic effect.

A very high coefficient of correlation (R2 > 95%) was obtained for the

relationship between the logarithm of DHA concentration and percent acute effect. It

should be noted that a poorer correlation was obtained for the data collected in December

1999, during a black liquor spill. This may be related to the presence of other toxicants

and changes in system parameters, among other effects.

C. dubia dose-response experiments

As mentioned earlier, pH is a critical parameter in assessing the toxicity of

ionizable compounds such as DHA. Table 4.4 details the pH ranges encountered over the

course of the experiments. Although no effort was made to control pH, variations were

modest.

81 Table 4.4. Sample pH range over duration of chronic dose-response experiments.

Sample Final Effluent Final Effluent w/DHA spike 11/06/00 8.1 8.1 11/08/00 8.0 8.2 11/10/00 8.0 8.5 Demineralized water 7.9 8.6

The pH used in these experiments is on the upper end of the range found in most

effluent treatment systems. DHA toxicity is inversely related to pH21; acute toxicity

decreases with increasing pH. Hydrophobicity of DHA also decreases with increasing pH. This is due to the effect of the carboxylic acid group on solubility. The pKa of DHA

is 5.722 and increasing pH will increase ionization and solubility, and decrease

23 hydrophobicity. Hydrophobic compounds with logKow around 5 tend to bioconcentrate .

As pH increases from 6 to 8, the logKow for DHA has been estimated to decrease from

roughly 5 to around 324. Octanol:water partitioning coefficient estimations exceed 106 based on group contribution methods for the neutral form of DHA. This has implications on the partitioning behavior of DHA to TSS. That is, more DHA will be in the water column at higher pH where it is more readily degradable25. Most effluent treatment systems are not operated at or above pH 8. Resin acids become less mobile at lower pH levels, resulting in a reduced potential extent of biological removal due to decreased

21 Zanella, E. (1983) Effect of pH on acute toxicity of dehydroabietic acid and chlorinated dehydroabietic acid to fish and Daphnia. Bull. Environm. Contam. Toxicol. 30, 133-140. 22 Nyren, V. and Back, E. "The Ionization Constant, Solubility Product and Solubility of Abietic and Dehydroabietic Acid" in Acta chemica Scandinavica, 12(7), (1958), pp. 1516-1520. 23 Muir D.C.G. and Servos M.R. (1996) Bioaccumulation of bleached kraft pulp mill related organic chemicals by fish, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, 283-296. 24 Werker A.G. (1998) The effect of pH on microbial activity and community structure in the biological removal of resin acids from wastewater. PhD, University of British Columbia, Vancouver, p. 190. 25 Leach J.M., Mueller, J.C. and Walden, C.C. (1977) Biodegradability of toxic compounds in pulp mill effluents. Transactions of the technical section CPPA, 3(4), TR126-TR130. 82 bioavailability26. Thus, hydrogen ion concentration changes over an order of magnitude

will have a significant effect on both the ability of effluent treatment systems to

mineralize DHA and the associated toxicity.

Results of December 2000 testing on the unspiked final effluent indicated no

chronic toxicity to survival, but did indicate chronic toxicity to reproduction. The NOEC

for survival was 100% effluent and for reproduction was 25%. The LOEC for

reproduction was therefore 50% and the EC50 for reproduction was calculated as 41%.

Results for the spiked effluent indicated chronic toxicity to both survival and reproduction. The NOEC for survival was 25%, LOEC of 50%, and an EC50 of 34%.

The NOEC for reproduction was 10%, LOEC of 25%, and EC50 of 15%. The effects of final effluent untreated and spiked with DHA on reproduction are shown graphically in

Figure 4.3. This figure illustrates the effect of the DHA spike (squares) on C. dubia

reproduction, compared with the treated final effluent control (diamonds). The

corresponding EC50 for chronic toxicity was approximately 2.0 ppm DHA. Results from

Mill C support these findings (Appendix A.2).

26 Werker A.G. (1998) The effect of pH on microbial activity and community structure in the biological removal of resin acids from wastewater. PhD, University of British Columbia, Vancouver, p. 73. 83 35 Final Effluent Final Effluent (w/DHA spike) 30 ys a 25 r 7 d e

t 20 af

s e

t 15 a on

e 10 n

# 5

0 0 102030405060708090100 Concentration, %

Figure 4.3. Effect of final effluent unmodified and amended with DHA on number of C. dubia neonates reproduced.

In the absence of a spill, the effluent DHA averaged about 30% of this value over

the course of 14 collection trips. If RFAs are spilled into the lagoon, their concentrations

will be increased until the spike is washed out. In other words, if plug flow conditions

applied, then a high RFA concentration would be found in the effluent for a short period.

Mixing lowers this concentration but lengthens the duration of elevated RFA levels in the

effluent. The EC50 for reproduction to C. dubia measured in Mill A effluent was 2 ppm.

27 A higher IC25 value of 6.6 ppm was reported earlier , but this test was run in well water where the contribution of other toxicants was absent. Hence, the final effluent DHA value is just below the EC50 threshold in the absence of a spill, and may exceed it for a prolonged period under upset conditions.

27 O’Connor B.I., Kovacs T.G. and Voss R.H. (1992) The effect of wood species composition on the toxicity of simulated mechanical pulping effluents. Environ. Toxicol. Chem. 11 1259-1270. 84

4.5. Section Summary

The main findings of this section indicate that the Microtox® acute toxicity threshold for DHA in real mill effluents is around 3-4 ppm, and the C. dubia chronic toxicity EC50 for reproduction is around 2 ppm DHA. The data add to the current body of knowledge on the toxicity of DHA in binary aqueous systems. Specifically, mills should find the information of more direct utility, as the wastewater matrix is more representative of the conditions encountered in the field. The results indicate that the presence of other toxicants can lower the toxic threshold of DHA as compared to results obtained in binary aqueous systems. Therefore, these results can be interpreted as more conservative than previous chronic studies.

Furthermore, these studies provide some insight into the effects of transient shock loading of DHA on final effluent acute and chronic toxicity. It was shown earlier, by this research and others, that neither laboratory nor at least 1 full-scale bioreactor could

adequately respond to such spikes in DHA concentration. This highlights the need for alternative DHA (and RFA) removal technologies to aid the ETS, particularly in environments that may be exposed to highly variable resin and fatty acid wastewater loading. The next chapter maps the pulp and paper mill sewer system to identify RFA source streams. Once such streams are identified and the important process parameters are known, selective removal strategies will be tested in the subsequent chapter.

85 5. Mapping Pulp Mill Sewers for Resin and Fatty Acids

5.1. Section Overview

The previous chapters have shown that resin and fatty acids may partition to

hydrophobic solids during effluent treatment and be poorly removed biologically. It was

shown that acute and chronic toxicity are related to resin and fatty acid concentration.

Additionally, the acute and chronic toxicity thresholds for dehydroabietic acid in real mill effluents were determined. These thresholds were found to be on the order of magnitude of DHA final effluent concentrations following a black liquor spill in Mill A. The typical final effluent DHA concentrations at this mill were between 30% and 50% of the experimentally determined acute and chronic thresholds, respectively.

Therefore, it has been shown that resin and fatty acids in general, and DHA specifically, can navigate through effluent treatment systems under normal operating conditions in the presence of hydrophobic solids and end up in the final effluent at concentrations approaching toxicity thresholds. Mills with inefficient or bottleneck primary treatment systems should pay particular attention to these findings, as the results indicate that higher solids loading into the secondary treatment system will hinder biological removal of RFAs. Furthermore, as mills move toward water system closure, it is likely that the discharged concentration of RFAs will increase as effluent volume decreases.

It is clear that additional strategies for removing RFAs from wastewater streams are needed in situations such as the aforementioned if toxicity excursions are to be

86 avoided. The choice of a technically feasible separation process should be based on

exploiting differences between physicochemical properties of resin and fatty acids and

the aqueous matrix from which they are to be removed. Thus, the first objective of this

chapter is to determine a separation process that could be used to selectively remove resin

acids from pulp mill streams.

Additionally, selecting a target stream for any removal process requires careful

consideration. The second objective of this chapter is to identify low volume, high concentration RFA source streams and the operating conditions that will influence a separation process.

The sewers of an integrated paper mill in the Southeastern U.S. were analyzed for resin and fatty acids (RFAs) and the process parameters of temperature, pH, and flow rate were measured. Two sources were found to contribute approximately 30% of the total

RFA load to primary treatment. These sewer streams were then considered for use in laboratory separation studies. For the purposes of this chapter, all sewers in the integrated mills studied are termed pulp mill sewers.

5.2. Experimental Approach

As demonstrated in previous chapters, a need exists for developing an alternate technology capable of selectively removing RFAs from the pulp mill system, preferably prior to secondary treatment. Effective separations processes exploit a physicochemical property of the contaminant of interest to selectively remove it from a matrix stream.

87 Depending on these properties, some separation processes and driving forces are listed in

Table 5.1.

Table 5.1 – Separation processes and operating principles28.

Separation process Operating principal Sedimentation Density differential/gravity Distillation Vapor pressure Extraction Partitioning coefficient Ultrafiltration Molecular size/shape Precipitation Solubility Adsorption Surface sorption Ion exchange Chemical reaction equilibrium Scrubbing Solubility Foam separation Surface activity Reverse osmosis Diffusivity and solubility

The first step in selecting a separation process is to identify the physicochemical

properties that differentiate resin and fatty acids from other contaminants and the aqueous

matrix. Dehydroabietic acid (Figure 5.1) is once again used as a reference resin acid. The relevant properties for DHA are shown in Table 5.2

COOH

Figure 5.1 – Chemical structure of DHA.

28 Null, H.R. (1987) “Selection of a separation process” in Handbook of Separation Process Technology, R.W. Rousseau (ed.), John Wiley & Sons, New York, NY, pp. 982-994. 88

Table 5.2 – Physicochemical properties of DHA.

DHA Property Value Molecular Weight (g/gmole) 300 Melting point (oC) 171.5-172.5 Solubility, neutral form (ppm) 6.6 Solubility, potassium salt (ppm) 7,500 pKa (20oC) 5.7 Log Kow (neutral form) 6.5 Log Kow (dissociated) 3.5 Henry’s Law constant (unitless) 7.28 x 10-6

The data in Table 5.2 provide some insight into what types of separation

processes and operating conditions may selectively remove DHA from wastewater

streams.

Resin and fatty acids are of relatively low molecular weight compared to the

dispersed lignin and suspended solids present in pulp mill sewers. As such, membrane

filtration would prove costly due to high pressure drops and low permeate flows.

Solubility is related to melting point, to the extent that lattice energy represents the

amount energy required to break apart molecules prior to being solvated29. Resin acids have significantly higher melting points than fatty acids. They exhibit low solubility in neutral and acid pH conditions. However, solubility is orders of magnitude higher at the elevated temperatures and pH encountered during pulping. RFAs are surface active at alkaline pH, and successful (if not economical) effluent detoxification has been reported

29 Yalkowsky, S. H.; Banerjee, S. Aqueous Solubility. Methods of Estimation for Organic Compounds; Dekker: New York, 1992. 89 using foam fractionation30. Furthermore, resin and fatty acids are weak carboxylic acids with dissociation constants within the pH range of normal pulping operations. The pKa of

DHA is approximately 5.7, compared to 6.4 for abietic acid31.

Partitioning of compounds among environmental compartments (aqueous,

hydrophobic and air) can be predicted from octanol:water partitioning coefficients (Kow) and Henry’s Law constants. For ionogenic hydrophobic compounds, Kow is influenced by pH and ionic strength32. The data in Table 5.2 were estimated assuming that only the

neutral fraction is present in the nonaqueous phase and activity corrections are negligible.

The RFAs exhibit exceedingly low vapor pressures at ambient temperatures, and can be considered nonvolatile.

The secondary treatment system is a poor choice for such a process as it has two characteristics that pose significant separation challenges. First, it is a high volumetric flow rate stream; on the order of 30-40 million gallons per day in the case of Mill A.

Treating such a large volume is an inherent barrier to process economics. Second, the concentrations of resin and fatty acids entering the treatment system are very low, and decrease as treatment progresses. As shown in Figure 3.5, individual fatty acids typically

enter treatment below 2 ppm and resin acids below 4 ppm. Selectively removing

contaminants at such low concentrations could be compared to finding a needle in a

30 Ng K.S. (1977) Detoxification of bleached kraft mill effluents by foam separation. PhD, University of British Columbia, Vancouver. 31 Nyren, V. and Back, E. "The Ionization Constant, Solubility Product and Solubility of Abietic and Dehydroabietic Acid" in Acta chemica Scandinavica, 12(7), (1958), pp. 1516-1520. 32 Westall J.C. (1985) Influence of pH and ionic strength on the aqueous –nonaqueous distribution of chlorinated phenols. Environmental Science & Technology, 19, 193-197. 90 haystack. A logical alternative is to trace the wastewater sewer system and determine the volumetric flow rates, RFA concentrations and process parameters of the source streams feeding primary treatment.

Resin acids and fatty acid esters undergo saponification during pulping; DHA gets converted to sodium resinate. As previously discussed, the salt is three orders of magnitude more soluble than the neutral form. The potassium and sodium salts of DHA are surface active and will concentrate at hydrophobic interfaces, such as air, dissolved lignin, unbleached wood-derived solids, etc. Thus, concentrating resin acids at the air:water interface through foam fractionation is a potential separation process in high pH systems. However, resin and fatty acids are not the only surface active agents in pulp mill sewers. Lignosulphates are more surface active and much more abundant than resin and fatty acids and will compete for interfacial area.

Increasing the hydrogen ion concentration converts the soaps back to their neutral form. This allows for solubility, and partitioning, to be effectively controlled by the pH of the system. Streams with high suspended solids may exploit this relationship prior to primary clarification. Solids may also be removed using flotation by depending on the size of the solids and their surface hydrophobicity. The surface may be modified using surfactants to promote attachment to air bubbles. The size distribution of the solids will determine if settling or flotation will be the dominant removal mechanism for low pH systems, assuming adequate residence time, as shown in Figure 5.2.

Figure 5.2 – Particle size ranges for various separation processes33.

Based on the preceding analysis, the properties of interest for selecting a wastewater sewer stream to locate a resin and fatty acid separation process include temperature, pH, solids concentration, size distribution and tendency to foam. Thus, the combination of RFA concentration and sewer flowrate (relative loading to treatment system) and aqueous properties of the main pulp mill sewers will be considered.

Previous results indicated that the pulp mill sewer and the evaporator condensates might represent relatively low volume, high concentration sources for resin and fatty acids34. These data are compared to field measurements at two integrated pulp mills in the southeastern U.S.

33 Holik, H. “Unit operations and equipment in recycled fiber processing” in Recycled Fiber and Deinking, L. Gottsching and H. Pakarinen (ed.), Fapet Oy, Helsinki, (2000) p. 93. 34Kemeny, T.E. and Banerjee, S. "Correlations Among Contaminant Profiles in Mill Process Streams and Effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 151-158. 92 5.3. Experimental

The mills studied were Mill A and B, described in chapter 3. The sewers were analyzed for temperature, pH, flowrate, conductivity, suspended solids and RFA concentration. Some of the RFA samples were filtered through glass fiber filters to determine the amount of RFA sorbed to total suspended solids (TSS). Particle size was determined using a Malvern 2600 model Droplet and Particles Size Analyzer. Sampling trips were made on four occasions, from March 2000 to July 2002. The purpose of these trips was to collect samples from the pulp mill sewers to identify sources of resin and fatty acids (Figure 5.3).

Process parameters including flow rate, temperature, and pH were measured in the field. Where available, these data were collected from DCS and strip chart recorders.

In the absence of readily available flow rate data, magnetic flow meters and material conservation balances were used to measure and estimate sewer flows. Suspended solids and conductivity were measured at the mills immediately following collection. RFA samples were prepared, shipped and tested at a later time according to the procedures described previously.

Wood Yard (Dry Debarking) 3.0 MGD 7.0 Power House/ MGD Recovery Boiler

Digesters 7.2 MGD Evaporators 3.0 MGD Br own Stock Washers 7.6 MGD Paper Mill 6.0

MGD Alkaline 34 Bleach Plant Acid MGD

6.0 Primary MGD Treatment

Secondary Treatment

Final 40 Effluent MGD

Figure 5.3 – Mill A wastewater sewer system.

94 5.4. Results and Discussion

One of the main challenges associated with selectively removing resin and fatty

acids from the primary and secondary treatment systems is the large volume (~ 32-40

mgd). The inflow to primary treatment is made up of many “source streams” of widely

varying flow rate. Therefore, identifying source streams of relatively high RFA

concentration and low, but significant, flow rate was the first objective of this study. As

sources vary between mills, the sewers analyzed here were selected based on relative

contribution to primary treatment and the type of unit operation producing the flow. In

this framework, the purge streams analyzed were the brownstock washer decker filtrate

(pulp mill decker), the evaporator sewer, the pre-bleach plant thickener filtrate, and the

acid and alkaline bleach plant effluents. The results of the RFA analysis for the sewers

are presented in Table 5.3.

Table 5.3 - RFA concentration, flow rate, temperature and pH of Mill A sewers.

RFA concentration, Pulp Mill Caustic and Bleach Alkaline Acid µg/g Decker Evaporators Plant Press Bleach Plant Bleach Plant Palmitic 0.50 0.81 3.22 4.80 2.23 Linoleic 1.70 0.10 2.69 0.35 0.54 Oleic 3.91 0.17 2.69 1.39 1.37 Stearic 0.34 0.17 0.78 1.20 0.64 Linolelaidic 0.70 0.07 2.15 0.00 0.00 Pimaric 1.33 0.09 0.57 0.36 0.11 Sandaracopimaric 0.52 0.00 0.25 0.00 0.00 Palustric 0.59 0.00 0.44 0.00 0.00 Isopimaric 2.92 0.14 0.82 0.00 0.00 Dehydroabietic 3.82 0.38 1.27 2.29 1.30 Abietic 7.17 0.37 3.14 0.00 0.00 Neoabietic 1.67 0.00 0.54 0.00 0.00 Total RFA, µg/g 25.15 2.29 18.56 10.38 6.19 Flow rate - MGD 3.0 7.2 3.0 3.0 6.0 Temperature - oC 32 44 50 63 57 pH 6.3 10.2 8.6 11.0 2.4

95 It is clear that of the sewers analyzed, the pulp mill decker filtrate and bleach plant press have the highest resin and fatty acid concentrations. It is also important to consider not only concentration, by also sewer flow rate, as the combination of these terms defines the total RFA loading for each sewer to the effluent treatment system.

Finally, normalizing these figures by the total loading to the primary clarifier allows for the identification of the most significant relative source of resin and fatty acids in the mill. This exercise has been carried out in Tables 5.4 and 5.5 for Mills B and C. The results in Table 5.3 can be compared to the measurements made at Mill B (Table 5.4) and those for Mill C previously reported in literature (Table 5.5).

Table 5.4 – RFA concentration, flow rate, temperature and pH of Mill B sewers.

RFA concentration, Pulp Mill Paper Mill Caustic Others* Primary Final µg/g Sewer Sewer Sewer Clarifier In Effluent Palmitic 1.92 0.79 0.69 2.30 1.61 0.14 Linoleic 6.00 0.60 0.21 1.80 2.72 0.09 Oleic 6.87 0.56 1.20 8.17 5.01 0.15 Stearic 0.57 0.16 0.36 1.20 0.63 0.06 Pimaric 2.12 0.12 0.83 2.53 1.58 0.22 Sandaracopimaric 0.55 0.00 0.48 0.73 0.45 0.11 Palustric 3.73 0.09 2.44 1.83 2.06 0.00 Isopimaric 1.74 0.12 0.56 -0.13 0.63 0.15 Dehydroabietic 5.43 1.16 3.40 6.87 4.52 1.09 Abietic 9.34 0.85 1.97 8.41 6.06 0.22 Neoabietic 3.42 0.00 0.16 0.28 1.24 0.00 Total RFA, µg/g 41.69 4.45 12.30 33.99 26.51 2.23 Flow rate - MGD 2.5 2.0 0.75 2.3 7.5 7.5 Temperature - oC 48 36 43 -- 34 33 pH 5.5 11.2 11.6 -- 7.5 7.3 Fractional flow** 33% 27% 10% 30% 100% 100% Fractional RFA** 52% 4% 5% 38% 100% 8% * Calculated from material balances, ** Relative to flow/concentration at primary clarifier

96 Table 5.5 – RFA sewer concentration, flow and treatment system loading in Mill C.

Total resin acids, ppm Pulp Mill Recovery Evaporator Alkaline Acid Primary Final Episode Sewer Sewer Sewer Sewer Sewer Clarifier Effluent 1 95 103 19 24 0.9 32 0.4 2 59 171 21 42.2 7 43 1.2 3 123 0.5 378 20.0 3.1 53 4.0 4 3,800 2.4 15 55.7 3.5 43 1.9 5 1.5 0.1 452 13.3 3.7 27 0.1 6 1.1 0.1 89 20.1 4.1 37 0.1 7 0.7 0.5 5.4 17.8 1.5 4 0.1 8 49 0.9 8.8 23.4 1.3 12 0.1 Average 515 35 124 27.1 3.1 31 1.0 Flowrate, MGD Pulp Mill Recovery Evaporator Alkaline Acid Primary Final Episode Sewer Sewer Sewer Sewer Sewer Clarifier Effluent 1 1.5 0.1 12 1.8 7.6 18 19 2 0.9 0.1 1.0 1.8 7.6 17 18 3 0.9 0.1 0.3 1.8 7.6 18 25 4 0.7 0.1 1.2 1.8 7.6 18 24 5 0.6 0.1 1.3 1.8 7.6 18 25 6 0.6 0.1 0.7 1.8 7.6 9 15 7 0.7 0.0 0.4 1.8 7.6 2 28 8 0.6 0.0 1.2 1.8 7.6 21 26 Average 0.8 0.1 0.9 1.8 7.6 15 23 % Flow contribution 5% 0.4% 6% 12% 50% 100% RFA loading, kg/day Pulp Mill Recovery Evaporator Alkaline Acid Primary Final Episode Sewer Sewer Sewer Sewer Sewer Clarifier Effluent 1 540 40 85 170 25 2,200 25 2 200 58 80 290 200 2,800 80 3 420 0.1 430 140 90 3,700 400 4 10,000 0.5 70 380 100 3,000 200 5 4 0.0 2,200 90 110 1,900 5 6 3 0.0 250 140 120 1,300 9 7 2 0.0 8 120 40 30 9 8 110 0.1 40 160 40 950 8 Average 1,400 12 400 185 90 2,000 90 % RFA contribution 72% 1% 20% 9% 5% 100% 4%

97 As was expected, the pulping sewers (including brownstock washing filtrates) are

the most significant source of resin and fatty acids to the treatment system. The alkaline

bleach plant sewer and pre-bleach plant washer press filtrates were also found to be

concentrated sources of RFAs. Due to differences in the sewer configurations between

Mill A and Mill C, the evaporator sewers at Mill A were not found to be a high-

concentration, low-volume RFA source, as previously reported for Mill C.

Based on these concentrations and flow rates, the pulp mill decker filtrate and the

pre-bleach washer press were chosen as model systems for laboratory flotation

experiments. Each of these streams represents approximately 8% of the volumetric flow

to the primary clarifier (32 MGD) and 15% of the total RFA loading.

The two samples selected for this study represented pH conditions near the

extremes found in most pulp mills. The pulp mill decker filtrate stream operates at pH 6

and the pre-bleach washer press operates near pH 9. Also, the decker filtrate TSS was

360 ppm and that of the washer press was 45 ppm. A typical particle size distribution for

the decker filtrate TSS is shown in Figure 5.4. The number-weighted mean diameter for

this distribution was 59 µm, and the specific surface area was estimated to be 0.20 m2/g.

Thus, the decker filtrate represents 72 m2 of interfacial area per cubic meter of water

volume. The particle size distribution for the pre-bleach washer press filtrate is shown in

Figure 5.5. The mean particle diameter was 49 µm and the specific surface area averaged

0.24 m2/g TSS or 11 m2/m3 of washer filtrate. More than 77% and 83% of the particles

were smaller than 100 µm for the decker filtrate and washer press, respectively.

98 40

30 ) (% y c

n 20 e u q e Fr

0 50 100 150 200 Particle size, d (µm) p Figure 5.4 – Suspended solids distribution for the pulp mill decker filtrate samples.

30 ) % cy (

n 20 e u q e Fr

0 50 100 150 200

Particle size, dp (µm) Figure 5.5 Particle size distribution for the pre-bleach washer press filtrate.

99 Preliminary foaming studies have indicated that the pulp mill sewer is the best

stream for foam fractionation due to high foaming tendency. The sewer samples were

screened for foaming ability by bubbling air through a 100 milliliter aliquot in a 250

milliliter Erlenmeyer flask. However, foams generated from both sewers exhibited good

foam stability.

5.5. Section Summary

The first objective of this chapter was to analyze the properties of resin acids that

can be exploited by separation technologies based on various operating principles.

Flotation has been selected as a potentially feasible separation technology, as resin and fatty acids concentrate at air:water interfaces in alkaline conditions and sorb strongly to hydrophobic solids in acidic conditions. Depending on the pH conditions, it is expected that RFAs sorbed to hydrophobic solids will be more effectively removed at neutral to acidic pH than by foam fractionation.

The other main objective of this chapter was to map the pulp mill sewer system to identify major RFA source streams of relatively low-volume and high-concentration.

Studying the sewers of Mill A has provided some key process data necessary for selecting source streams to stage an RFA separation process. Specifically, it has been

shown that relatively low volume, high RFA concentration streams contribute a

significant fraction of the resin and fatty acid loading to the effluent treatment system.

The existence of more than one such source stream provides the opportunity to compare

the removal efficiencies in each stream. As such, the pulp mill decker and pre-bleach

100 washer press filtrates were chosen for laboratory investigations into the technical feasibility of selectively removing resin and fatty acids from pulp mill wastewater sewers using flotation. This is the subject of the next chapter.

101 6. Resin and Fatty Acids Removal from Pulp Mill Sewers using Flotation

6.1. Section Overview

In previous chapters, resin and fatty acids (RFAs) in the final effluent were related

to chronic toxicity. Additionally, partitioning to hydrophobic solids was shown to be a

significant RFA removal pathway from the water column. Incomplete fine solids removal

in primary treatment is responsible for roughly 60% of the RFA loading to the secondary

treatment system. Improving solids removal from pulp mill wastewater streams may

reduce RFA loading to the effluent treatment system. Flotation is commonly used to

improve solids removal in wastewater treatment and other processes. Due to economic

considerations, examining the technical feasibility of RFA removal using flotation should

target low-volume, high-concentration source streams.

The sewers of integrated pulp and paper mills in the Southeastern U.S. were

analyzed for RFAs and the process parameters of temperature, pH, and flow rate were measured. Two sources were found to contribute approximately 30% of the total RFA load to primary treatment. This chapter examines the viability of RFA removal from these sewer streams using a laboratory flotation column. The following experiments focus on the removal of RFAs attached to suspended solids. In addition, a kinetic model for solids removal was applied for the bubbly flow regime, and predictions were compared to experimental results.

102 6.2. Experimental Approach

As discussed in previous chapters, the chemical structures of resin and fatty acids

consist of both hydrophilic and hydrophobic groups. The balance between these groups

makes RFAs surface active at high pH35. Their aqueous solubility is a strong function of pH, and RFAs tend to sorb to hydrophobic solids in neutral conditions36. Therefore,

RFAs should concentrate at the air-water interface under alkaline conditions, and associate with total suspended solids under neutral and acid conditions. During flotation,

air-water interfaces are created with air bubbles and both surfactants and hydrophobic

particles can be concentrated in the resulting foam.

The study of flotation with the objective of removing resin and fatty acids from

wastewater streams is not new. In fact, toxicity reduction of dilute black liquor as a result

of bubbling had been documented nearly sixty years ago37. Prior to synthetic surfactants, resin and fatty acid soaps were extensively used as foaming agents. Early documentation of the ability of sodium resinate to dissolve insoluble hydrocarbons in aqueous solution dates back to the late 19th century38. Considerable fundamental research was conducted in

the 1950s to determine the surface activity, solubility and ionization constants of abietic

and dehydroabietic acid39,40. The results of these studies are reflected in Table 5.2 of the

35 Ström, G. (2000) Physio-chemical properties and surfactant behavior. In Back, E.L., and Allen, L.H., Editors. Pitch Control, Wood Resin and Deresination. Atlanta, GA: Tappi Press. 36 Hall, E.R. and Liver, S.F. (1996) Interaction of resin acids with aerobic and anaerobic biomass – II. Partitioning on biosolids. Wat. Res. 30(3), 672-678. 37 Ng, K.S., Mueller, J.C., and Walden, C.C. (1973) Detoxification of kraft mill effluents by foam separation. Pulp Paper Mag. Can. 74(5), 119-123. 38 Ström G. (2000) Physio-chemical properties and surfactant behavior. In Back, E.L., and Allen, L.H., Editors. Pitch Control, Wood Resin and Deresination. Atlanta, GA: Tappi Press. 39 Bruun, H. (1952) Properties of monolayers of rosin acids. Acta chemica Scandinavica. 29(3), 494-501. 40 Nyren, V. and Back, E. (1958) The Ionization Constant, Solubility Product and Solubility of Abietic and Dehydroabietic Acid. Acta chemica Scandinavica, 12(7), 1516-1520. 103 previous chapter. These findings have also been the basis for more recent flotation

studies.

Investigators have studied using dispersed air flotation for detoxifying kraft mill

effluents41, removing surfactants from spent sulfite liquor42 and dilute kraft black liquor43, and removing resin acids from white water44. Fatty acids are also commonly

used as collectors in flotation processes for mineral enrichment45.

Early pulp and paper industry foam fractionation research examined its potential to detoxify pulp mill final effluents46. Resin and fatty acids were known to be both surface active and toxic. Flotation was found to be an effective method for final effluent detoxification. However, flotation was only effective with significant alterations to system pH. For example, acid bleach effluent was completely detoxified at pH 9.5, while caustic extraction effluent was only effectively detoxified at pH 2.5. No changes in resin and fatty acid concentration were reported. Toxicity was measured as median survival time for salmon exposed to 100% strength effluents. Complete detoxification was defined as 100% survival following 96 hours of exposure. These studies illustrated the potential to remove toxic compounds from pulp mill wastewater streams using flotation.

41 Ng, K.S., Mueller, J.C., and Walden, C.C. (1973) Detoxification of kraft mill effluents by foam separation. Pulp Paper Mag. Can. 74(5), 119-123. 42 Zajic, J.E., Berk, D., and Behie, L.A. (1979) Foam fractionation of spent sulphite liquor, Part I: Separation of surfactants. Canadian Journal of Chemical Engineering 57(6), 321-332. 43 Brasch, D.J. and Robilliard, K.R. (1979) Rates of continuous foam fractionation of dilute kraft black liquor. Separation Science and Technology, 14(8), 699-709. 44 Tay, S. (2001) Effect of dissolved and colloidal contaminants in newsprint machine white water on water surface tension and paper physical properties, Tappi Journal, 84(8). 45 Somasundaran, P. and Ananthapadmanabhan, K.P. (1987) “Bubble and foam separation – ore flotation” in Handbook of Separation Process Technology, R.W. Rousseau (ed.), John Wiley & Sons, New York, NY, pp. 775-803. 46 Ng, K.S. (1977) Detoxification of bleached kraft mill effluents by foam separation. PhD, University of British Columbia, Vancouver. 104

Foam fractionation was also applied to the removal of surfactants from spent

sulphite liquors (SSL)47,48. The key findings centered on the role of pH in flotation of pulp-derived surface-active components. Specifically, increasing pH increased surfactant removal and reduced toxicity of the SSL. In fact, surface tension of the SSL at

intermediary fractionation treatment times was positively correlated to median survival

times of Daphnia magna, indicating a decrease in toxicity with increasing surface tension. Both the increased surface tension and decreased toxicity after foaming was attributed primarily to the removal of resin and fatty acids. However, it was also observed fractionation was only effective at pH greater than 8. The effect of hydrophobic solids was not considered, as fiber was filtered from the SSL samples prior to the study.

Other research has investigated the use of foam fractionation to separate surface- active components from dilute kraft black liquor49. This complex, multi-component

system was found to be well represented by a semi-empirical equation developed for a

binary aqueous surfactant solution. The model related the mass flow rate of black liquor

solids removed in the foam to gas flow rate and the concentration of black liquor solids in

the treated bottoms stream. The utility of the model is severely impaired by the use of

three adjustable parameters, which are related to the particular experimental setup. Thus,

the equation provides little insight into underlying principles governing removal rates.

47 Zajic, J.E., Berk, D., and Behie, L.A. (1979) Foam fractionation of spent sulphite liquor, Part I: Separation of surfactants. Canadian Journal of Chemical Engineering 57(6), 321-326. 48 Berk, D., Zajic, J.E., and Behie, L.A. (1979) Foam fractionation of spent sulphite liquor, Part II: Separation of toxic components. Canadian Journal of Chemical Engineering 57(6), 327-332. 49 Brasch, D.J. and Robilliard, K.R. (1979) Rates of continuous foam fractionation of dilute kraft black liquor. Separation Science and Technology, 14(8), 699-709. 105

The prior research has indicated the potential to remove surfactants from pulp mill

wastewaters using flotation. However, no systematic attempts have been made to relate

the removal of resin and fatty acids from pulp wastewaters to the more general

parameters driving the flotation processes. Additionally, the prior work has focused on

direct adsorption of surface-active components to air bubbles and concentration in the

foam. The results of previous chapters have indicated that resin and fatty acids sorb

strongly to pulp derived solids at pH conditions commonly encountered in pulp mill

sewers. Foaming frequently occurs at pH conditions below those required for resinate

formation. As such, if sufficient hydrophobic solids are present, then sorbed resin and

fatty acids may effectively be removed from sewers via particle adsorption to air bubbles

during flotation.

The objective of this research was to determine the extent to which resin acids can

be removed using flotation from key low-volume, high-concentration source streams, i.e.

pulp mill sewers feeding the effluent treatment system. Of particular interest is the

interaction between resin acids and suspended solids, as a significant removal pathway in

the effluent treatment system is sorption to hydrophobic solids and settling50,51.

50 Liu, H., Lo, S., and Lavallée, H. (1996) Mechanisms of removing resin and fatty acids in CTMP effluent during aerobic biological treatment. Tappi Journal, 79(5), 145-154. 51 Makris, S, P., and Banerjee, S. (2002) Fate of resin acids in pulp mill secondary treatment systems. Water Research, 36, 2878-2882. 106 Solids removal using flotation has been modeled extensively in the literature52,53,54,55,56 using relationships that range from empirical to first principles. In general, the change in concentration with time in a reactor element, neglecting differences in radial or angular positions, can be written as

2 2 dC1/dt = P*d C1/dz - u1*dC1/dz - R1 (6-1)

3 where C1 is the solids concentrations (g/m ) in the liquid phase, P the liquid phase

2 dispersion coefficient (m /s), z the column length (m), u1 the superficial liquid velocity

3 (m/s), and R1 the solids removal rate (g/m ).

For semi-batch conditions of no liquid flow (u1 = 0) and under well-mixed conditions within the differential element, Equation 6-1 reduces to

dC1/dt = -R1 (6-2)

52 Dobby, G.S. and Finch, J.A. (1986) Flotation column scale-up and modeling. CIM Bulletin, 79(889), 89-96. 53 Chen, S. (1991) Theoretical and experimental investigation of foam separation applied to aquaculture. PhD, Cornell University, New York. 54 Oliveira, J.F., Saraiva, S.M., Pimenta, J.S., and Oliveira, A.P.A. (2001) Kinetics of pyrochlore flotation from araxa mineral deposits. Minerals Eng. 14(1), 99-105. 55 Szatkowski, M. and Freyberger, W. L. (1985) Kinetics of flotation with fine bubbles. Trans Inst Min Metall Sect C 94, 61-70. 56 Rubinstein, J.B. and Samygin V.D. (1998) Effect of particle and bubble size on flotation kinetics. In: Laskowski, J.S. and Woodburn, E.T., Editors. Frothing in Flotation II. Amsterdam, Netherlands: Gordon and Breach Science Publishers. 107 Four gas flow regimes are typically identified in bubble column studies, namely

bubbly flow, transition or imperfect bubbly flow, churn turbulent and slug flow57. The

flow regime is a function of superficial gas velocity (volumetric air flow rate normalized

by column area) and the type of sparger. The solids removal rate varies with

hydrodynamic flow regime. More generally, flow regime is related to Reynolds number;

as bubble radius increases, for a given fluid, Reynolds number increases and the shape of

the bubble changes from a sphere to an ellipsoid. For creeping flow up to moderate

Reynolds number (Re ~ 800) the bubble can be considered spherical58.

Surfactant and solids removal using flotation in the moderate Reynolds number (<

700), i.e. the bubbly flow regime, has been modeled by Chen59. Solids removal rate can be related to operational parameters and a collection efficiency term as

2 dC1/dt = -R1 = -KE*C1*ug*(rp/(rb *(1-Eg)*U∞)) (6-3)

where, KE is the fine suspended particle removal coefficient (m/s), ug the

superficial gas velocity (m/s), rp the suspended solid particle radius (m), rb the bubble radius (m), Eg the dimensionless gas holdup (volume percentage of gas in liquid), and U∞ the terminal bubble velocity (m/s). Equation 6-3 is roughly appropriate for bubbles of diameter in 1-3 mm range, which is the range determined in the following experiments.

57 Bouaifi, M., Hebrard, G., Bastoul, D., and Roustan, M. (2001) A comparative study of gas hold-up, bubble size, interfacial area and mass transfer coefficients in stirred gas-liquid reactors and bubble columns. Chemical Engineering and Processing, 40, 97-111. 58 Levich, V.G. (1962) Physicochemical hydrodynamics. Prentice-Hall, Englewood Cliffs, N.J. 59 Chen, S. (1991) Theoretical and experimental investigation of foam separation applied to aquaculture. PhD, Cornell University, New York. 108

The solution to Equation 6-3 is

2 ln(C1f/C10) = -KE*ug*(rp/(rb *(1-Eg)* U∞))tf (6-4)

where the subscripts 0 and f represent initial and final conditions, respectively, with tf the flotation treatment time (s). The sole adjustable parameter, KE, can be

calculated once all of the other variables are experimentally determined. Solids removal

rates can then be predicted for that system.

Establishing the resin acid TSS:water partitioning coefficient then allows for

predicting resin acid removal rates based initial solids concentration, superficial gas

velocity, particle and bubble radius, bubble terminal rise velocity and time. It is assumed

that the resin and fatty acid partitioning is an equilibrium process. Therefore, a fractional

removal of suspended solids will correspond to a similar reduction in sorbed resin and

fatty acids. As such, solids removal is a proxy for sorbed RFA removal.

6.3. Experimental

The samples used in this study were collected from the pulp mill decker filtrate

and pre-bleach plant washer press filtrate at Mill A. Samples for laboratory flotation

studies were collected in 5-gallon steel buckets in June 2002 and sealed airtight prior to

storage. Twenty-five gallons were collected from each sewer location. Characterization

109 of these streams for resin and fatty acid concentration, total suspended solids,

temperature, pH and conductivity followed the procedures described in previous chapters.

A schematic of the experimental flotation system is provided in Figure 6.1. The

setup consists of a bulk reservoir with impeller mixer and temperature-control system,

liquid and gas feed systems with flow meters, a glass column with exchangeable bubble stones, a foam collection attachment and pH and temperature probes. The bulk reservoir is a six-gallon, open glass tank. Temperature was controlled using a circulating heating bath in the sample reservoir and heat tape on the fractionation column. Temperature could be varied between ambient (23 oC) and above 35 oC, with average system variation between ±0.5 oC.

Figure 6.1. Schematic of experimental flotation column.

110 UHP air was delivered from gas cylinders to the bubble column through flow

meters, regulated at 25 psi. The flow meters were calibrated using the capillary bubble

rise method. Liquid is delivered from the reservoir to the fractionation column by indirect

contact using a peristaltic pump with flexible silicon tubing. The system can be operated

in either semi-batch or continuous mode.

The column is 1.2 meters in length and 5.0 centimeters in diameter, with 5

sampling ports. Foam is directed through a U-shape attachment on the top of the column

into a glass receptacle. The typical column liquid volume for this study was 2.7 liters.

Samples were collected from one of five equally-spaced sampling ports and/or from the

foam collector.

Operational parameters of importance include gas flow rate, bubble size

distribution, gas holdup, terminal bubble velocity and temperature. Bubble size distribution was varied using fine, medium and coarse porosity sintered-glass bubble stones. Bubble size was measured using image analysis (Image Pro Plus, Media

Cybernetics®) of digital photos. Generally, the bubbles were spherical, however the software can correct ellipsoids and calculate an effective spherical diameter. The bubbles at the wall were measured and taken as representative of those in the column. This assumption is based on the observation that the bubbles in the focal field near the wall

(within 0.75 cm of the wall) represent one half of the unit volume of the 5 cm diameter column. Total bubbles measured to estimate a given distribution varied from 150 to 200.

Representative bubble images for the various bubble stones are shown in Figure 6.2

111

Figure 6.2. Images used for bubble-size image analysis.

Typically, mean bubble sizes are reported as the Sauter mean bubble diameter,

dbs, which is the number averaged volume to surface area. This averaging technique has been found to minimize the difference in bubble size distributions between various bubble size measurement techniques60. Sauter mean diameter is calculated as:

3 2 dbs = Σ(nidbi )/ Σ(nidbi ) (6-5)

where ni is the number of bubbles with a diameter dbi (m).

60 Shah, Y.T., Kelkar, B.G., and Godbole, S.P. (1982) Design parameters estimations for bubble column reactors. AIChE Journal, 28(3), 353-379. 112 Gas holdup was determined from the difference in liquid column height with and

without airflow, following system equilibrium. In general, for the bubbly flow regime,

gas holdup increases linearly with superficial gas velocity for a given bubble size

distribution. Terminal bubble velocity was determined by video capture and image

analysis. Terminal bubble velocity decreases with decreasing bubble diameter, thereby increasing residence time. Thus, both contact time and interfacial area are controlled by bubble diameter.

The column was operated in semi-batch mode, with each data point representing a freshly charged column. The time t=0 samples represent the bulk reservoir concentration, while at time t=x, 250 ml had been sampled from the column at 0.6m above the sparger.

Samples were also analyzed for TSS to determine the removal rate of solids with time.

6.4. Results and Discussion

One of the main challenges associated with selectively removing resin and fatty acids from the primary and secondary treatment systems is the large volume (~ 32 mgd).

The inflow to primary treatment is made up of many “source streams” of widely varying flow rate. Therefore, identifying source streams of relatively high RFA concentration and low, but significant, flow rate was the first objective of this study. As sources vary between mills, the sewers analyzed here were selected based on relative contribution to primary treatment and the type of unit operation producing the flow. In this framework, the purge streams analyzed were the brownstock washer decker filtrate (pulp mill

113 decker), the evaporator sewer, the pre-bleach plant thickener filtrate, and the acid and alkaline bleach plant effluents.

Table 6.1 summarizes the results of the RFA analysis for the sewers from the previous chapter. Based on these concentrations and flow rates, the pulp mill decker filtrate and the pre-bleach washer press were chosen as model systems for laboratory flotation experiments. Each of these streams represents approximately 8% of the volumetric flow to the primary clarifier (32 mgd) and 10 to 15% of the total RFA loading.

Table 6.1. RFA concentration, flow rate, temperature and pH of sewer samples.

Sewer Pulp Mill Pulp Mill Bleach Alkaline Acid Decker Caustic and Plant Bleach Bleach Evaporators Press Plant Plant Total RFA, µg/g 25.15 2.29 18.56 10.38 6.19 Flow rate, MGD 3.0 7.2 3.0 3.0 6.0 Temperature, oC 32 44 50 63 57 pH 6.3 10.2 8.6 11.0 2.4

Bubble size varied with bubble stone and, to a lesser extent, superficial gas velocity. Figure 6.2 qualitatively shows the differences between bubble size distributions generated with the fine, medium and coarse bubble stones. The maximum bubble size did not increase much with coarser stones, though there was a decrease in the relative proportion of smaller bubbles. The result was a larger average bubble size.

114 In this study, volumetric airflow rate was varied from 100 to 1200-ml/min, corresponding to superficial gas velocity ranges of 0.001 m/s to 0.010 m/s. The change in gas holdup with superficial gas velocity is shown in Figure 6.3. It was found that the superficial gas velocity range studied was entirely within the bubbly flow regime. With an upper limit of 0.010 m/s, gas holdup is expressed well by:

Eg = 7.60*ug (6-6)

0.10

0.08 ess) l n o si 0.06 en m i d ( g E , p

u 0.04 d l o as H

G 0.02

0.00 0.000 0.002 0.004 0.006 0.008 0.010 0.012

Superficial gas velocity, ug (m/s)

Figure 6.3. Gas holdup as a function of superficial gas velocity.

115 The average bubble size varied between 0.92 mm to 2.1 mm as a result of changing bubble stones. A typical bubble size distribution is shown in Figure 6.4, with a

Sauter mean diameter of 1.4 mm. The resulting terminal bubble rise velocity was determined to be 0.061 m/s.

40 y nc que e r F

0.0 0.5 1.0 1.5 2.0 2.5 3.0 Mean bubble diamter, d (mm)

Figure 6.4. Bubble size distribution (Sauter mean diameter = 1.4 mm).

The two samples selected for this study represented pH conditions near the extremes found in most pulp mill sewers. The pulp mill decker filtrate stream operates at pH 6 and the pre-bleach washer press operates near pH 9. Also, the decker filtrate TSS was 360 ppm and that of the washer press was 45 ppm. Typical particle size distributions

116 for the TSS in the pulp mill decker and pre-bleach washer press filtrates were presented in Figures 5.4 and 5.5.

Early work had focused on the effect of TSS on the removal efficiency of RFA.

At pH 6, the main mechanism for RFA removal during flotation is sorption to TSS followed by attachment to rising bubbles and concentration in the foam. Figure 6.5 illustrates the relationship between the change in RFA and the change in TSS. Less than

10% of the RFA was removed when TSS was removed from the samples prior to bubble column introduction after residence times greater than 30 minutes. Approximately 85% of the RFAs were associated with the 360 ppm of TSS in the pulp mill decker samples.

0.5

0.4 ) l a v o m

e 0.3 r

l a n io t c a r f 0.2 ( A F R ∆

0.1

0 0.1 0.2 0.3 ∆TSS (fractional removal)

Figure 6.5. Fractional removal of RFA with TSS.

117 The average RFA TSS:water distribution coefficient was 9500, with a standard

deviation of 4600. It is clear that increasing RFA removal coincides with solids removal.

Thus, it was reasonable to assume that the majority of resin and fatty acids would be

removed via association with hydrophobic solids.

The experimental data were then used to calculate the fine suspended particle

removal coefficient, KE, using Equation 6-4. The values for initial and final solids concentration, superficial gas velocity, particle radius, bubble radius, terminal bubble rise velocity, and treatment time are tabulated in Table 6.2.

Table 6.2. Determination of particle removal rate coefficient, KE.

C1f ug (ppm) C10 (ppm) KE (m/s) (mm/s) rp (mm) rb (mm) Eg U∞ (m/s) tf (s) 125 134 5.6E-04 0.42 0.028 0.70 0.007 0.06 300 116 121 1.6E-04 0.42 0.028 0.70 0.007 0.06 600 91 102 3.2E-04 0.42 0.028 0.70 0.007 0.06 900 94 127 4.1E-04 2.55 0.028 0.70 0.03 0.06 300 120 127 4.0E-05 2.55 0.028 0.70 0.03 0.06 600 153 178 6.9E-05 2.55 0.028 0.70 0.03 0.06 900 161 186 4.5E-05 10.0 0.028 0.70 0.13 0.06 300 176 193 1.8E-05 10.0 0.028 0.70 0.13 0.06 600 156 177 1.3E-05 10.0 0.028 0.70 0.13 0.06 900 average: 1.8E-04 std. dev. 2.0E-04

-4 The average value for KE was found to be of the order of 10 m/s. This is the sole adjustable parameter in the solids removal rate equation. As such, equation 6-4 can now be used to predict solids removal rates and compared to experimental results.

118

Figure 6.6 shows the predicted and experimental removal of suspended solids with time. The data represent gas flow conditions near the extremes tested in this study.

100

80 g n i n i a m

e 60 R S % TS

ug = 0.003 m/s

Pred. ug = 0.003 m/s

ug = 0.010 m/s

Pred. ug = 0.010 m/s

051015 Time, minutes

Figure 6.6. Removal of TSS from decker filtrate with time and airflow rate.

The experimental removal rates are less than those predicted by equation 6-4, particularly at high superficial gas velocities. At lower ug, experimental and predicted solids removal rates were generally in good agreement. However, removal rates were poorly predicted at ug on the order of 0.01 m/s. It is near this superficial velocity that the bubble flow regime changes from bubbly to transition flow. As Equation 6-4 was developed for low bubbly flow, it is not surprising to see the large deviations illustrated in Figure 6-6. Physically, at higher superficial velocities particles and bubbles share a

119 decreased residence time during which attachment can occur, thereby reducing the

probability of attachment. This probability is lumped into KE, the collection efficiency that was averaged over a range of velocities. Additionally, the bubble size distribution approximation made by measuring bubbles near the column wall will also affect the model coefficient. Measuring only the bubbles near the wall underestimates the true

distribution, which results in an overestimation of removal efficiency by the model.

Figure 6-6 depicts the tradeoff in applying Equation 6-4 to make predictions over

a broader set of initial conditions. In an effort to use just one KE for a given bubble size distribution, significant error is introduced when using the equation at the upper boundary of the bubbly flow regime. As such, the remaining data presented is well within the bubbly flow regime.

Figure 6.7 shows the removal of RFA from the pulp mill decker filtrate (pH = 6.3) with time and airflow rate, using the fine bubble stone and at ambient temperature (23

o C). Removal efficiency ranged from 18% at ug = 2mm/s to 25% at ug = 3mm/s. The

predicted removal rates using Equation 6-4 are represented by the dashed lines. The

equation predicts continuing reduction in solids concentration, as well as sorbed RFA

concentration. The experimental and predicted RFA removals are in good agreement at

treatment times up to 15 minutes.

The reduction observed experimentally levels off after roughly 15 minutes of

treatment time, though the predicted values are still falling. In calculating the collection

120 efficiency, KE, 15 minutes was the maximum treatment time used for this reason. If removal rates for longer treatment times were included, then the predictions may have been in better agreement with experimental results. However, the standard error of the prediction increases substantially in this situation. This is due to the decreasing correlation between treatment time and solids removal. Physically, surface tension is increasing as treatment time progresses in a semi-batch system. Solids removal, in fact, is less correlated with treatment time after roughly 15 minutes for this system. Thus, applying the model outside the range of conditions for which it was developed yields misleading predictions, as shown in Figure 6.7.

100

90 g n i n i a

m 80 Re e g a t n e c

r 70 A Pe RF

60 ug = 0.002 m/s

Pred. ug = 0.002 m/s

ug = 0.003 m/s

Pred. ug = 0.003 m/s

0 5 10 15 20 25 Time, minutes

Figure 6.7. Removal of RFA from decker filtrate with time and airflow rate.

121 Figure 6.8 illustrates the removal of RFA from the pre-bleach washer press (pH =

9.0) with time and airflow rate, using the coarse bubble stone and at ambient temperature.

RFA removal efficiency ranged from 9% to 30%. Again, the predicted removal rates using Equation 6-4 are represented by the dashed lines.

100

ining 90 a m e R

ge 85 a t n e c r e 80 A P F R

ug = 0.002 m/s Pred. u = 0.002 m/s 75 g ug = 0.003 m/s

Pred. ug = 0.003 m/s

051015 Time, minutes

Figure 6.8. Removal of RFA from pre-bleach washer press with time and air flow rate.

These conditions represent the upper end of the pH range for the model. In this case, the measured RFA removal rates were greater than the predicted rates. This is because it was assumed in the model that RFAs are only removed by sorption to suspended solids coupled with solids removal by flotation. At elevated pH, RFAs sorb

122 directly to air bubbles and are removed via foam fractionation. As such, a dual

mechanism model should be used at pH greater than 8.

Since the goal of any separation process is to have a concentrated reject stream, the collapsed foam volume as a percentage of treated liquid volume is an important measurement. Typical foam mass was 0.4 to 0.8 % of the liquid treated during flotation.

Thus, for mills limited by evaporator capacity, concentration by flotation and disposal in the recovery loop may represent a valuable means to reduce RFA loading to the secondary treatment system.

Finally, the significance of the results was determined for the a representative set of experiments, namely superficial velocity of 3 mm/s, fine bubble stone, and pH 6 for the pulp mill decker filtrate. Table 6.3 summarizes the fraction of RFA remaining at intermittent treatment times for five trials and the analysis of variance.

Table 6.3. ANOVA for resin and fatty acid removal with treatment time.

Treatment time 5 minutes 10 minutes 15 minutes RFA remaining Trial 1 0.92 0.87 0.79 Trial 2 0.91 0.82 0.78 Trial 3 0.87 0.88 0.84 Trial 4 0.88 0.80 0.72 Trial 5 0.92 0.72 0.70 Average 0.90 0.82 0.77 Standard error 0.023 0.064 0.056 Sum of squares Mean squares F-values SSbetween 0.0456 0.0228 F-measured 8.72 SSwithin 0.0314 0.0026 F-critical 3.88 SStotal 0.0770 P-value 0.0046

123 The low P-value compared to the significance level of 0.05 indicates that the

increasing treatment time increases RFA removal.

6.5. Section Summary

Foam flotation can be used to remove resin and fatty acids from pulp mill sewers

at moderate to high pH. RFA concentration was decreased by 25%, on average, and two

mechanisms were determined. RFAs partitioned to total suspended solids (TSS) and were

removed by solids concentration in the foam. Foam concentrates were between 0.4 and

0.8 %, on a volume basis. In these experiments, it was found that total suspended solids

removal is a good predictor of resin and fatty acid removal. As such, modeling the solids

removal provides insight into the operational parameters that can be adjusted to improve

RFA separation. Increasing treatment time, increasing superficial gas velocity and

decreasing bubble size, all improve RFA removal and TSS removal, though with

decreasing marginal returns. This illustrates the limitations of the theoretical model. The

relationship between gas holdup and superficial gas velocity indicates that increasing ug has the added benefit of increasing Eg, and subsequently enhancing solids removal rate.

However, the predicted and experimental values diverge as the superficial gas velocity

approaches the transition regime around 0.010 m/s. Furthermore, the model predicts that

increasing suspended solids particle size will increase TSS, and therefore RFA, removal

using foam flotation. This is balanced against the increased magnitude of the gravity

force.

124 7. Conclusions and Recommendations

This final chapter unites the results of the previous chapters in the major

dissertation findings, as well as recommendation for future research. The main

dissertation objectives were to determine: the relationship between resin and fatty acids

and toxicity in a full-scale effluent treatment system; the role suspended solids played in

RFA removal from the water column; and the feasibility of removing RFAs from pulp

mill sewers using flotation. These objectives were based on clarifying and extending the

prior understanding of resin and fatty acid behavior in pulp and paper mill wastewater

systems.

It was hypothesized that since resin and fatty acids were some of the more

recalcitrant organics in the ETS, their removal will significantly influence the acute and

chronic toxicity levels in the final treated effluent. Chapters 3 and 4 presented the

experimental approach taken to test these hypotheses and discussed the results obtained.

The first step was to determine the relationship between changes in resin acid

concentration and changes in acute and chronic toxicity across the treatment system. The

Microtox® whole effluent test bioassay was used as a proxy for acute toxicity and the

Ceriodaphnia dubia 7-day survival and reproduction bioassay was used to measure chronic effects.

The profiles of resin and fatty acids, specifically DHA, indicated that these compounds were quite difficult to remove in three full-scale integrated pulp and paper

125 mill effluent systems. This conclusion is based largely on the changes in concentration of these compounds across the treatment system of the mill primarily considered in this dissertation, and confirmed at other similar mills. Though 75-95% of the BOD is removed, predominantly in the first two reactors, only 45% of the dissolved resin and fatty acids are removed during the same space-time. Total RFA reduction is closer to

70% due to proportionately greater removal of the sorbed fraction. As such, RFA sorption to solids represents a significant removal pathway, as removal of TSS-sorbed fraction accounts for two thirds of the total RFA reduction. Furthermore, DHA remains one of the principal resin acids in the final effluent.

Toxicity was found to decrease early in secondary treatment, more closely tracking changes in resin and fatty acids than the changes in bulk organics (BOD and

COD). Oxygen demand to mineralize organics does not change significantly across the second reactor. However, this is where the bulk of the toxicity is removed. Many of the compounds entering the first reactor are completely removed, such as monoterpenes and sulfur-based compounds. Still there are toxicants present at sufficient concentration to cause toxic responses in both the acute and chronic assays at 10% concentration and below. This indicates that the compounds responsible for residual toxicity are not adequately removed from the first reactor. Resin and fatty acid concentrations are reduced in both the first and second reactors. Based on the results of 10 field bioassays, dissolved resin and fatty acids were found to be responsible for a significant fraction

(~60%) of chronic toxicity.

126 It was also hypothesized that if full-scale effluent treatment systems cannot

effectively remove shock loads of RFAs, then a need exists for pulp mills to develop

alternative RFA removal systems in order to reduce the risk of toxicity outbreaks

associated with process upsets. Chapter 3 also provided field data to support this

hypothesis, while Chapter 4 presented laboratory findings of a simulated dehydroabietic

acid shock load. It was shown that the full-scale effluent treatment system could not

adequately respond to spikes in RFA concentration. The data collected following a black

liquor spill confirms that although secondary treatments systems may be responsive to

COD spikes, RFA spikes are not readily treated.

By using dehydroabietic acid (DHA) as a model resin acid, the threshold

concentration in the final effluent was determined. The main findings from the laboratory

toxicity studies indicate that the Microtox® acute toxicity threshold for DHA in real mill

effluents is around 3-4 ppm (in the absence of suspended solids), and the C. dubia

chronic toxicity EC50 for reproduction is approximately 2 ppm DHA. Mills will be able to

compare these measures with typical concentration ranges in the treated effluent and

quantify their risk of experiencing resin acid related toxicity problems. The results

indicate that the presence of other toxicants can lower the toxic threshold of DHA as

compared to results obtained in binary aqueous systems.

This highlights the need for alternative DHA (and RFA) removal technologies to

aid the ETS, especially in environments that may be exposed to highly variable resin and fatty acid wastewater loading. The understanding gained in the partitioning studies

127 presented an opportunity to apply the results of this work to the development of a process to selectively remove RFAs from a pulp mill source stream.

Due to their hydrophobic nature, RFAs were expected to partition with other hydrophobic materials in the ETS, such as biomass and pulp-derived solids. The specific effect of these interactions had not been previously reported. The role of suspended solids in removing RFAs from the water column was clarified in Chapter 3. It was found that sorbed resin and fatty acids are poorly removed during primary treatment at 65%. Key findings include approximately half of the resin and fatty acids entering secondary treatment are sorbed to suspended solids and nearly the entire sorbed fraction is removed prior to final effluent discharge. Partitioning data indicate that resin and fatty acids have an affinity for Kappa 70 pulp fibers 4 to 5 orders of magnitude greater than for water.

This is due to the small differences between pKa for these compounds and the pH operating conditions of the effluent treatment system.

Finally, process conditions were expected to have a strong and predictable influence on the extent to which RFAs could be removed from pulp mill sewers using flotation based on an understanding of their partitioning behavior. Chapters 5 and 6 presented the results of field studies to identify RFA source streams and process conditions and laboratory flotation studies using key sewer sources. The streams selected covered a wide range of pH and temperature found in the wastewater sewer system.

128 Based on the physico-chemical properties of resin and fatty acids, flotation was

selected as a potentially feasible separation technology, as these compounds concentrate

at air:water interfaces in alkaline conditions and sorb strongly to hydrophobic solids in

acidic conditions. Studying the sewers of Mill A provided some key process data

necessary for selecting source streams to stage an RFA separation process. Specifically, it

was found that relatively low-volume, high-concentration streams contribute a significant

fraction of the resin and fatty acid loading to the effluent treatment system. The existence of more than one such source stream provided the opportunity to compare the removal efficiencies in each stream under different operating conditions. Laboratory investigations were carried out to determine the technical feasibility of selectively removing resin and fatty acids from pulp mill wastewater sewers using flotation.

Foam flotation removed resin and fatty acids from pulp mill sewers at moderate to high pH by two mechanisms. At pH below 9.0, the primary RFA removal mechanism was partitioning to suspended solids followed by solids adsorption to air bubble and concentration in the foam. At pH 9.0 and higher, some RFAs directly partitioned to the air:water interface in addition to removal with solids. However, in studies with solids removed and up to pH 10, RFAs were removed only at 10%. As reported by previous researchers, though foaming increased at higher pH, resin and fatty acid removal was not improved. This is due to competition from other surface-active agents of higher concentration, such as low molecular weight lignosulphates. The effect of temperature was also found to agree with previous studies. Increasing temperature was found to decrease removal rates. The volume of the concentrated foam streams was fairly low.

129 Collapsed foam concentrates were less than 1 % on a volume basis. This volume should be easier to handle in evaporator-limited mills than concentrating the entire sewer stream.

In these experiments, it was found that TSS removal is a good predictor of resin and fatty acid removal. As such, a kinetic model for solids removal was augmented with

RFA equilibrium partitioning data to predict RFA removal based on solids removal. The operational parameters that can be adjusted to improve RFA separation included increasing treatment time, increasing superficial gas velocity and decreasing bubble size.

The relationship between superficial gas velocity and gas holdup indicates that increasing gas flow rate in the bubbly flow regime has the added benefit of increasing interfacial area, and subsequently enhancing solids removal rate. Furthermore, the model predicts that increasing suspended solids concentration will increase sorbed RFA concentration and removal. As such, the addition of primary sludge may enhance the removal process.

On average, RFA concentration could be decreased by 25% using flotation under the most optimum conditions. These conditions included using the fine bubble stone to generate smaller bubbles, increasing the superficial gas velocity while staying in the bubbly flow regime, and increasing treatment time. Though 25% may not seem large compared to the total RFA loading, it does represent a quantifiable reduction. Mills that experience toxicity or other problems related to resin and fatty acids may find such an opportunity to be quite useful. The potential to increase this amount exists. For example, no collectors or flocculants were used in this study. The surface of the suspended solids

130 could be made more hydrophobic or the solids could be made larger. Both would improve the solids removal rate, the former by increasing the collection efficiency.

During the course of this research, areas for future exploration became apparent.

The results of this study are valid for kraft pulps, however extension to mechanical pulps would be of great interest to industry. For example, the effluent treatment systems of mechanical pulp mills must handle higher RFA concentrations by two to three orders of magnitude. However, the surface properties of mechanical fibers are different from chemical fibers. Less hemicellulose is removed during mechanical pulping. Chemical pulp fiber surfaces have 2-3 times the lignin content of the wood structure. Mechanical pulping fiber surfaces more closely resemble the original composition of the wood.

Although primary treatment was not the focus of this project, the implications of this work are relevant to both settling tanks and dissolved air flotation units.

Enhancement of solids removal in these unit operations represents another means of reducing RFA loading to the treatment system. Conversely, efforts to increase throughput will reduce residence time and could adversely affect RFA concentrations entering secondary treatment. Although partitioning was treated as an equilibrium process in this study due to the long residence times involved, the dynamics of sewer stream mixing and entering the primary treatment system represents a continuation of this work. The changes in pH and temperature are sure to cause a redistribution of RFAs among fiber and water. For example, some mills mix the bleach plant acid and alkaline sewer streams

131 prior to primary treatment. This could have the effect of either solvating or precipitating

RFAs depending on the relative flows, pH and temperature differences.

Although the understanding gained from the partitioning studies was applied to pulp-derived solids and wastewater, other areas would benefit from this work. Resin and fatty acids are commonly associated with pitch problems in the paper mill. The role of pH on RFA partitioning in fiber:water systems can be applied to this area as well. Recycle mills encounter pitch problems and also use tall oil derivatives as process aids in flotation to remove ink from pulp.

Finally, many researchers feel confident that well-run treatment systems can remove upwards of 95% of the resin and fatty acid concentrations being encountered today. However, the future will likely see progressively higher mill water system closure.

Similar to naturally occurring non-process elements, resin and fatty acids will build up in the water system unless a sufficient purge stream exists. Complete closure of the brownstock washers and bleach plant effluents may send all of the wastewater to the evaporators and then to the recovery boiler. However, there is a tradeoff between energy efficiency and both brownstock and bleached pulp quality requirements. Higher dilution factors improve pulp quality, but hurt economics by increasing the evaporator load. It is more likely that either a wastewater purge stream will exist in one or both of these processes or a process “kidney” may be employed to remove undesirable components.

Purge streams represent higher RFA loading to the treatment system. As such, this work may be revisited as the basis for understanding likely distributions of resin and fatty acids

132 among fiber and water. Process kidneys may be used to clean impurities from the water system similar to the function of animal kidneys in biological systems. In addition to flotation, sorption, ultrafiltration, and chemical treatments among other technologies may be employed. The findings of this dissertation will provide a reference point for those who follow in this field.

133 APPENDIX A.1

Table A.1a. Summary of toxicity test conditions for the water flea, C. dubia, survival and reproduction for Mill A.

Test type Static renewal definitive Temperature 24.0-26.5 oC Light quality Ambient laboratory illumination Light intensity 10-20 �E/m2/s, or 50-100 ft-c Photoperiod 16 hrs light, 8 hrs darkness Test chamber size 30 ml Test solution volume 15 ml Renewal of test concentrations Daily Age of test organisms Newly hatched neonates, < 24 hrs old No. of neonates per test chamber 1 No. of replicate champers per concentration 10 No. of neonates per concentration 10 Feeding regime Fed 0.1 ml each of YCT and algae suspension per test chamber daily Aeration none Dilution water Moderately hard synthetic water is prepared using MILLIPORE MILLI-Q® and Perrier Effluent concentrations Control, 1%, 5%, 10%, 25%, 50%, 75%, and 100% Dilution factor Approximately 0.5 End points Survival and reproduction Test acceptability 80% or greater survival in controls; average of 15 of more young per surviving female in the control solutions. At least 60% of surviving females in controls should have produced their third brood. Sampling requirement Samples are collected daily, and used within 36 hrs of the time they are removed from the sampling device Sample volume required 1.0 L per day

134 Table A.1b. Initital chemical characterization of final effluent and controls used in chronic toxicity testing for Mill A.

Parameter 100% Reactor 4 Out (Final Effluent) DMW Control Sample Date 11/6/00 11/8/00 11/10/00 11/7/00 Temperature (oC) 1.5 4.0 4.0 25 Dissolved O2 (mg/L) 7.20 7.65 7.40 7.60 pH 8.09 7.99 7.99 7.60 Total Alkalinity as 213 412 442 73 CaCO3 (mg/L) Total Hardness as 408 408 384 80 CaCO3 (mg/L) Conductivity @ 25 2200 2185 2130 165 oC (µmhos/cm) Residual Chlorine < 0.01 < 0.01 < 0.01 < 0.01 (mg/L) Ammonia-nitrogen 7.0 7.15 5.89 < 0.01 NH3-N (mg/L)

Performed according to EPA 600/4 – 79/020, except for ammonia as nitrogen performed using Hach spectrophotometric test kit.

Table A.1c. Initital chemical characterization of final effluent and controls with DHA spike used in chronic toxicity testing for Mill A.

Parameter 100% Reactor 4 Out (Final Effluent w/DHA) DMW Control (w/DHA) Sample Date 11/6/00 11/8/00 11/10/00 11/7/00 Temperature (oC) 1.5 4.0 4.0 25 Dissolved O2 (mg/L) 6.70 7.55 7.70 7.50 pH 8.14 8.21 8.47 8.62 Total Alkalinity as 243 430 432 73 CaCO3 (mg/L) Total Hardness as 432 408 392 80 CaCO3 (mg/L) Conductivity @ 25 2165 2145 2100 183 oC (µmhos/cm) Residual Chlorine < 0.01 < 0.01 < 0.01 < 0.01 (mg/L) Ammonia-nitrogen 4.98 5.14 4.75 < 0.01 NH3-N (mg/L)

Performed according to EPA 600/4 – 79/020, except for ammonia as nitrogen performed using Hach spectrophotometric test kit.

135 Table A.1d. Daily survival and reproduction data for C. dubia chronic test of final effluent for Mill A.

0% Day Total 10% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 # nates # 1 A A A 2 6 A 10 9 27 31 A A A 3 A 3 9 12 27 12 A A A 2 6 A 3 10 21 52 A A A A 6 7 14 A 27 53 A A A 3 4 A 9 11 27 13 A A A 3 6 A 3 1 13 24 A A A 1 A 4 3 A 8 44 A A A 1 A 4 13 18 36 45 A A A 3 A 7 8 A 18 5 A A A 1 5 9 A 14 29 36 A A A 3 5 A 4 16 28 26 A A A A 4 7 A 19 30 17 A A A A A 4 4 14 22 47 A A A 4 7 A 6 24 41 58 A A A 4 A 4 X4 12 18 A A A A A 4 17 17 38 39 A A A A 3 A 4 14 21 59 A A A 2 4 A 13 16 35 10 A A A A 2 5 10 A 17 40 A A A 4 8 A 10 18 40 Original # Live neonates per 201 Original # females: Live neonates per 316 females: 10 female: 20.1 10 female: 31.6

1% Day Total 25% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 Neo- # nates # nates 11 A A A 4 A 2 15 A 21 1 A A A 1 4 A 8 12 25 42 A A A 2 6 4 A 16 28 12 A A A 1 A 3 A 7 11 33 A A A 2 2 A 6 15 25 53 A A A A 4 6 11 A 21 4 A A A A 4 A 2 13 19 24 A A A 1 A A 5 11 17 25 A A A 3 3 A 10 14 30 45 A A A 3 3 7 A 14 27 56 A A A 3 6 7 A 12 28 36 A A A 2 6 8 7 A 23 37 A A A 1 A 4 9 A 14 17 A A A 5 4 A 4 16 29 8 A A A A 1 7 10 A 18 58 A A A X 29 A A A A 2 A 1 11 14 39 A A A A A 1 13 13 27 50 A A A 3 6 A 10 16 35 10 A A A A 1 7 12 1 21 Original # females: Live neonates per 232 Original # females: Live neonates per 201 10 female: 23.2 10 female: 20.1

5% Day Total 50% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 Neo- # nates # nates 21 A A A 2 6 10 1 16 35 11 A A A 3 A 2 6 A 11 32 A A A A 3 A 3 13 19 42 A X 0 3 A A A 1 A 4 9 14 28 33 A A A 2 A A A 1 3 54 A A A 2 A 3 6 14 25 4 A A A A A 2 A 1 3 15 A A A A 3 A 9 14 26 25 A A A 3 1 A A 3 7 46 A A A 1 4 8 A 17 30 56 A A 3 1 1 5 4 X 14 7 A A A A 1 7 13 A 21 37 A A A 2 A A A 2 4 28 A A A A A 1 4 6 11 8 A A A 3 A 2 7 10 22 49 A A A A 4 A 6 10 20 29 A A A X 0 20 A A A 2 A 9 11 15 37 50 A A A A A A A 5 5 Original # females: Live neonates per 252 Original # females: Live neonates per 69 10 female: 25.2 10 female: 6.9

136 75% Day Total 100% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 # nates # 21 A X 0 31 A A A 1 A A A A 1 32 A A A 3 A A A A 3 52 A A 4 A A A A A 4 3 A A A A A A 8 10 18 13 A A A A A A A A 0 54 A A A A 2 1 A A 3 44 X 0 15 A A A 3 A 2 A A 5 5 A A A 3 A A A A 3 46 A A A 3 2 A A A 5 26 A A A 2 A A A A 2 7 A A A A A A 1 A 1 47 A A A X 0 28 A A A 2 A A A A 2 18 A A A 3 A A A A 3 49 A A A 3 A A A A 3 59 A A A A A A A A 0 20 A A A A 1 A 4 1 6 40 A A A A A A A A 0 Original # females: Live neonates per 46 Original # females: Live neonates per 13 10 female: 4.6 10 female: 1.3

A = alive adult; X = dead adult; # = number of live neonates

137 Table A.1e. Daily survival and reproduction data for C. dubia chronic test of final effluent with DHA spike for Mill A.

0% Day Total 10% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 # nates # 1 A A A 2 6 A 10 9 27 31 A A A A 4 A 6 6 16 12 A A A 2 6 A 3 10 21 52 A A A 2 6 A 2 9 19 53 A A A 3 4 A 9 11 27 13 A A A A 2 6 A 4 12 24 A A A 1 A 4 3 A 8 44 A A A A 4 9 A 8 21 45 A A A 3 A 7 8 A 18 5 A A A 1 4 10 A 7 22 36 A A A 3 5 A 4 16 28 26 A A A A 2 2 3 A 7 17 A A A A A 4 4 14 22 47 A A A A 5 6 1 5 17 58 A A A 4 A 4 X4 12 18 A A A 2 3 A 8 2 15 39 A A A A 3 A 4 14 21 59 A A A A 2 7 A 8 17 10 A A A A 2 5 10 A 17 40 A A A 1 5 4 A 7 17 Original # Live neonates per 201 Original # Live neonates per 163 females: 10 female: 20.1 females: 10 female: 16.3

1% Day Total 25% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 Neo- # nates # nates 11 A A A A 4 A 6 11 21 1 A A A A X 0 42 A A A A 5 A 6 20 31 12 A A A 2 A A A 2 4 33 A A A A 4 6 A 15 25 53 A A A A A 2 A A 2 4 A A A A 4 5 A 14 23 24 A A A A A A A A 0 25 A A A A 5 A 13 17 35 45 A A A A A 6 A A 6 56 A A A A 3 4 A 16 23 36 A A A A A A X 0 37 A A A 2 7 3 A 16 28 17 A A A 3 A A A 3 6 8 A A A A 3 5 A 20 28 58 A A A X 0 29 A A A 2 3 A 7 12 24 39 A A A A 2 A A A 2 50 A A A 3 4 4 A 17 28 10 A A A A A 7 A 1 8 Original # females: Live neonates per 266 Original # females: Live neonates per 28 10 female: 26.6 10 female: 2.8

5% Day Total 50% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 Neo- # nates # nates 21 A A A A 2 4 8 1 15 11 A X 0 32 A A A A 6 7 A 17 30 42 A X 0 3 A A A A 6 10 A 14 30 33 A A A A A A A 1 1 54 A A A 2 4 A 7 15 28 4 X 0 15 A A A A 4 6 A 17 27 25 A A A X 0 46 A A A A 4 6 A 11 21 56 X 0 7 A A A 3 5 7 A 16 31 37 A A A A X 0 28 A A A 1 5 8 A 18 32 8 A A X 0 49 A A A 1 2 9 A 2 14 29 A A X 0 20 A A A 3 2 7 A 12 24 50 A A X 0 Original # females: Live neonates per 252 Original # females: Live neonates per 1 10 female: 25.2 10 female: 0.1

138 75% Day Total 100% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 # nates # 21 X 0 31 X 0 32 X 0 52 X 0 3 A A X 0 13 X 0 54 X 0 44 X 0 15 A A X 0 5 A A 0 46 X 0 26 X 0 7 A A X 0 47 X 0 28 A A X 0 18 X 0 49 A A A A A X 0 59 X 0 20 X 0 40 X 0 Original # females: Live neonates per 0 Original # females: Live neonates per 0 10 female: 0.0 10 female: 0.0

A = alive adult; X = dead adult; # = number of live neonates

139 APPENDIX A.2

Table A.2a. Summary of toxicity test conditions for the water flea, C. dubia, survival and reproduction for Mill C.

Test type Static renewal definitive Temperature 24.5-26.5 oC Light quality Ambient laboratory illumination Light intensity 10-20 µE/m2/s, or 50-100 ft-c Photoperiod 16 hrs light, 8 hrs darkness Test chamber size 30 ml Test solution volume 15 ml Renewal of test concentrations Daily Age of test organisms Newly hatched neonates, < 24 hrs old No. of neonates per test chamber 1 No. of replicate champers per concentration 10 No. of neonates per concentration 10 Feeding regime Fed 0.1 ml each of YCT and algae suspension per test chamber daily Aeration None Dilution water Moderately hard synthetic water is prepared using MILLIPORE MILLI-Q® and Perrier Effluent concentrations Control, 1%, 10%, 20%, 30%, 50%, 75%, and 100% Dilution factor Variable End points Survival and reproduction Test acceptability 80% or greater survival in controls; average of 15 of more young per surviving female in the control solutions. At least 60% of surviving females in controls should have produced their third brood. Sampling requirement Samples are collected daily, and used within 36 hrs of the time they are removed from the sampling device Sample volume required 1.0 L per day

140 Table A.2b. Initital chemical characterization of final effluent and controls used in chronic toxicity testing for Mill C.

Parameter 100% Reactor 4 Out (Final Effluent) DMW Control Sample Date 7/23/01 7/25/01 7/27/01 7/24/01 Temperature (oC) 2.0 5.5 20.0 25.0 Dissolved O2 (mg/L) 5.90 7.09 n/a 6.69 pH 7.83 8.06 n/a 7.94 Total Alkalinity as 260 315 n/a 65.5 CaCO3 (mg/L) Total Hardness as 136 120 n/a 74 CaCO3 (mg/L) Conductivity @ 25 3000 2850 n/a 136 oC (µmhos/cm) Residual Chlorine 0.06 0.08 n/a < 0.01 (mg/L) Ammonia-nitrogen 2.01 1.54 n/a < 0.01 NH3-N (mg/L)

Performed according to EPA 600/4 – 79/020, except for ammonia as nitrogen performed using Hach spectrophotometric test kit.

Table A.2c. Initital chemical characterization of final effluent and controls with DHA spike used in chronic toxicity testing for Mill C.

Parameter 100% Reactor 4 Out (Final Effluent w/DHA) DMW Control (w/DHA) Sample Date 7/23/01 7/25/01 7/27/01 7/24/01 Temperature (oC) 2.0 5.5 20.0 25.0 Dissolved O2 (mg/L) 6.21 7.09 n/a 6.77 pH 8.25 8.06 n/a 8.62 Total Alkalinity as 263 315 n/a 73 CaCO3 (mg/L) Total Hardness as 124 124 n/a 80 CaCO3 (mg/L) Conductivity @ 25 3000 2910 n/a 183 oC (µmhos/cm) Residual Chlorine 0.06 0.08 n/a < 0.01 (mg/L) Ammonia-nitrogen 2.01 1.54 n/a < 0.01 NH3-N (mg/L)

Performed according to EPA 600/4 – 79/020, except for ammonia as nitrogen performed using Hach spectrophotometric test kit.

141 Table A.2d. Daily survival and reproduction data for C. dubia chronic test of final effluent for Mill C.

0% Day Total 20% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 # nates # 1 A A A A 4 10 12 26 31 A A A A 3 11 16 30 12 A A A A 3 5 14 22 52 A A A A 4 A A 4 53 A A A A 4 9 14 27 13 A A X 0 24 A A A A 4 11 16 31 44 A A A A 6 13 14 33 45 A A A A A 11 18 29 5 A A A A 5 12 14 31 36 A A A A 2 9 16 27 26 A A A A A 10 11 21 17 A A A A 3 10 15 28 47 A A A A 6 1 15 22 58 A A A A 10 2 14 26 18 A A A A A 10 12 22 39 A A A A 2 6 12 20 59 A A A A A 9 14 23 10 A A A A 3 9 14 26 40 A A A A 3 10 16 29 Original # Live neonates per 262 Original # Live neonates per 215 females: 10 female: 26.2 females: 10 female: 21.5

1% Day Total 30% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 Neo- # nates # nates 11 A A A A 5 A 11 16 1 A A A A 5 10 14 29 42 A A A A 2 9 16 27 12 A A A A 4 15 13 32 33 A A A A 3 12 12 27 53 A A A A 4 10 11 25 4 A A A A 6 13 14 33 24 A A A A 4 10 15 29 25 A A A A 3 11 16 30 45 A A A A 11 A 19 30 56 A A A A 5 7 17 29 36 A A A A 5 9 15 29 37 A A A A 4 10 17 31 17 A A A A 6 9 13 28 8 A A A A 4 8 X6 13 58 A A A A 10 A 13 23 29 A A A A 2 8 11 21 39 A A A A 5 10 16 31 50 A A A A 3 11 15 29 10 A A A A 5 13 12 30 Original # Live neonates per 256 Original # Live neonates per 286 females: 10 female: 25.6 females: 10 female: 28.6

10% Day Total 50% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 Neo- # nates # nates 21 A A A A 4 9 15 28 11 A A A A 3 A A 3 32 A A A A 4 10 17 31 42 A A A A 4 11 14 29 3 A A A A 4 6 8 18 33 A A A A 4 9 13 26 54 A A A A A 10 15 25 4 A A A A 5 10 13 28 15 A A A A 3 9 13 25 25 A A A A A 12 12 24 46 A A A A 8 A 16 24 56 A A A A 5 8 12 25 7 A A A A 5 8 16 29 37 A A A A 8 A 13 21 28 A A A A 4 12 12 28 8 A A A A 11 1 5 17 49 A A A A 4 11 15 30 29 A A A A 4 9 12 25 20 A A A A 5 11 14 30 50 A A A A 4 9 15 28 Original # Live neonates per 268 Original # Live neonates per 226 females: 10 female: 26.8 females: 10 female: 22.6

142 75% Day Total 100% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 # nates # 21 A A A A A 9 10 19 31 A A A X 0 32 A A A A A 9 5 14 52 A A A A A 4 A 4 3 A A A A A 7 12 19 13 A A A A A 6 15 21 54 A A A A A 7 13 20 44 A A A A A A A 0 15 A A A A 3 8 A 11 5 A A A A A 6 A 6 46 A A A A A 1 4 5 26 A A A A 2 3 A 5 7 A A A A A 4 A 4 47 A A A A 1 5 A 6 28 A A A A A 4 A 4 18 A A A A A 2 A 2 49 A A A A 2 5 X 7 59 A A A A A 4 8 12 20 A A A A A 4 10 14 40 A A A A A 1 A 1 Original # Live neonates per female: 117 Original # females: Live neonates per 57 females: 10 11.7 10 female: 5.7

A = alive adult; X = dead adult; # = number of live neonates

143 Table A.2e. Daily survival and reproduction data for C. dubia chronic test of final effluent with DHA spike for Mill C.

0% Day Total 20% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 # nates # 1 A A A A 5 7 12 24 31 A A A A A 9 A 9 12 A A A A 6 11 4 21 52 A A A A A A 2 2 53 A A A A 4 9 14 27 13 A A A A A 9 2 11 24 A A A A 2 12 13 27 44 A A A A A 1 8 9 45 A A A A 5 9 13 27 5 A A A A 3 1 5 9 36 A A A A 3 11 14 28 26 A A A A A 8 A 8 17 A A A A 4 8 11 23 47 A A A A A 11 10 21 58 A A A A 3 14 19 36 18 A A A A A A 7 7 39 A A A A 3 9 14 26 59 A A A A A 11 A 11 10 A A A A 4 10 15 29 40 A A A A 4 A A 4 Original # Live neonates per 268 Original # Live neonates per 91 females: 10 female: 26.8 females: 10 female: 9.1

1% Day Total 30% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 Neo- # nates # nates 11 A A A A 4 11 16 31 1 A A A A A A A 0 42 A A A A 7 12 13 32 12 A A A A A A A 0 33 A A A A 3 1 14 18 53 A A A A A A 9 9 4 A A A A 8 A 15 23 24 A A A A A A A 0 25 A A A A 5 12 A 17 45 A A A A A A A 0 56 A A A A 4 12 17 33 36 A A A A A A A 0 37 A A A A 4 12 A 16 17 A A A A A A A 0 8 A A A A 2 9 13 24 58 A A A A A A A 0 29 A A A A 4 10 13 27 39 A A A A A A A 0 50 A A A A 4 9 14 27 10 A A A A A X 0 Original # Live neonates per 248 Original # Live neonates per 9 females: 10 female: 24.8 females: 10 female: 0.9

10% Day Total 50% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 Neo- # nates # nates 21 A A A A 4 12 15 31 11 A A X 0 32 A A A A 5 10 13 28 42 A A X 0 3 A A A A 5 11 A 16 33 A A A A A A A 0 54 A A A A 6 11 13 30 4 A A A A A A A 0 15 A A A A 4 A 10 14 25 A A X 0 46 A A A A 5 10 13 28 56 A A A A A A A 0 7 A A A A 7 A 18 25 37 A A A A A A A 0 28 A A A A 4 12 2 18 8 A A A A X 0 49 A A A A 2 12 15 29 29 A A A A A A A 0 20 A A A A 3 11 16 30 50 A A A A A A A 0 Original # Live neonates per 249 Original # Live neonates per 0 females: 10 female: 24.9 females: 10 female: 0.0

144 75% Day Total 100% Day Total Cup 1 2 3 4 5 6 7 8 Neo- Cup 1 2 3 4 5 6 7 8 # nates # 21 A X 0 31 A X 0 32 A X 0 52 A X 0 3 A X 0 13 A A X 0 54 A A X 0 44 A X 0 15 A X 0 5 A X 0 46 A A X 0 26 A A X 0 7 A A X 0 47 A A X 0 28 A A X 0 18 A X 0 49 A X 0 59 A X 0 20 A X 0 40 A X 0 Original # Live neonates per 0 Original # females: Live neonates per 0 females: 10 female: 0.0 10 female: 0.0

A = alive adult; X = dead adult; # = number of live neonates

145 REFERENCES

American Forest & Paper Association. (1999) Agenda 2020 The Path Forward: An Implementation Plan. Washington, D.C.

Ahtiainen J., Nakari T., and Silvonen, J. (1996) Toxicity of TCF and ECF pulp bleaching effluents assessed by biological toxicity tests, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 33-40. Ard, T.A. and McDonough T.J. (1996) Toxicity assays in the pulp and paper industry- a review and analysis. IPST Technical Paper Series 608, Atlanta, GA.

Azur Environmental (1998) “Whole Effluent Toxicity Protocol” in MicrotoxOmniÔ Software.

Banerjee, S. (1994) A long-term study of process sewer and effluent constituents at the Georgia- Pacific Leaf River facility. IPST Project 3866 Report, Atlanta, GA.

Banerjee, S. (1987) Interrelationship between biodegradability, toxicity and structure for chlorophenols, in QSAR in Environmental Toxicology - II, K. Kaiser (ed.), Reidel, Dordrecht, Holland.

Berk, D., Zajic, J.E., and Behie, L.A. (1979) Foam fractionation of spent sulphite liquor, Part II: Separation of toxic components. Canadian Journal of Chemical Engineering 57(6), pp. 327-332.

Biermann, C.J. (1996) Environmental impact: aqueous effluent treatment, in Handbook of pulping and papermaking. 2nd ed., Academic Press, San Diego, pp. 287-290.

Bouaifi, M., Hebrard, G., Bastoul, D., and Roustan, M. (2001) A comparative study of gas holdup, bubble size, interfacial area and mass transfer coefficients in stirred gas-liquid reactors and bubble columns. Chemical Engineering and Processing, 40, pp. 97-111.

Brasch, D.J. and Robilliard, K.R. (1979) Rates of continuous foam fractionation of dilute kraft black liquor. Separation Science and Technology, 14(8), pp. 699-709.

Bruun, H. (1952) Properties of monolayers of rosin acids. Acta chemica Scandinavica. 29(3), pp. 494-501.

Carlberg G.E (1993) Characterization of effluents from mechanical pulp production. EUCEPA International Environmental Symposium Proceedings, pp. 45-52.

146 Carlberg, G.E. and Stuthridge, T.R. (1996) Environmental fate and distribution of substances, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 169- 178.

Catesm D.H.; Eggert, C.; Yang, J.L.; and Eriksson, K.L. (1995) Comparison of effluents from TCF and ECF bleaching of kraft pulps. Tappi Journal, 78(12), pp. 93-98.

Chabot, B.; Daneault, C; Sain, M.M.; and Dorris, G.M. "On the Adverse Role of Fibres During the Flotation of Flexographic Inks" in 9th International Symposium on Wood and Pulping Chemistry: 1997: Poster Presentations, Montreal, Quebec, (1997), pp. 18-1-18-4.

Chen, S. (1991) Theoretical and experimental investigation of foam separation applied to aquaculture. PhD, Cornell University, New York.

Clesceri, L.S., Eaton, A.D. and Greenberg, A.E. (1999) Standard Methods for Examination of Water & Wastewater. 20th ed., New York: American Public Health Association.

Cook, D.; Parrish, A.; Borton, D.; and Hall, T. (1998) A summary of pulp and paper mill experiences with toxicity reduction and toxicity identification evaluations (TRE/TIE), in 1998 International Environmental Conference & Exhibit Proceedings, Tappi Press, Atlanta, GA, pp. 1081-1094.

Dahlman, O.B.; Reimann, A.K.; Stromberg, L.M.; and Morck, R.E. (1995) High-molecular- weight effluent materials from modern ECF and TCF bleaching. Tappi Journal, 78(12), pp. 99- 109.

Dave, G. (1993) Replicability, repeatability and reproducibility of embryo-larval toxicity tests with fish, in Progress in Standardization of Aquatic Toxicity Tests, A.M.V.M. Soares and P. Calow (ed.), Lewis Publishers, Boca Raton, FL, pp. 129-157.

Deng, Y. and Abazeri, M. (1998) Contact angle measurement of wood fibers in surfactant and polymer solutions. Wood and Fiber Science, 30(2), pp. 155-164.

Dobby, G.S. and Finch, J.A. (1986) Flotation column scale-up and modeling. CIM Bulletin, 79(889), pp. 89-96.

Drew, J. and Propst, M. (1981) Tall oil soap recovery, in Tall Oil, published by the Pulp Chemicals Association, New York. pp. 17-22.

Eklund, B.; Linde, M.; and Tarkpea, M. (1996) Comparative assessment of the toxic effects from pulp mill effluents to marine and brackish water organisms, in Environmental Fate and Effects of

147 Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 95-105.

Environment Canada. (2003) National Assessment of Pulp and Paper Environmental Effects Monitoring Data: A Report Synopsis. National Water Research Institute, Burlington, Ontario. NWRI Scientific. p. 19.

Firth, B.K. and Backman, C.J. (1990) Comparison of Microtox testing with rainbow trout (acute) and Ceriodaphnia (chronic) bioassays in mill wastewaters. Tappi J., 73(12), pp. 169-174.

Fisher, R.P.; Barton, D.A.; Wiegand, P.S. (1996) An assessment of the significance of discharge of chlorinated phenolic compounds from bleached kraft pulp mills, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 107-117.

Foran, C.D. "Tall Oil Soap Recovery" in 1996 Kraft Recovery Short Course Notes, Tappi Press, Atlanta, GA, (1996), Session 4, Paper no. 3, pp. 1-31.

Friese, M.A. and Banerjee, S. (1992). Lignin determination by FT-IR. Applied Spectroscopy 46 (2), pp. 246-248.

Fuller, W.A. Online article: Is AOX obsolete as a regulatory parameter for bleached kraft pulp mill effluent?. Accessed from University of Alberta Internet website: http://stud1.acad.athabascau.ca/html/groups/fota/aox.html, on November 17, 1998.

Gutierrez, L.A.; Mueller, J.C.; Ng, K.S.; and Walden, C.C. (1979) Detoxification of kraft mill effluents by foam separation - pilot plant studies. Pulp & Paper Canada, 80(11), pp. 87-92.

Hall, E.R. and Liver, S.F. (1996) Interaction of resin acids with aerobic and anaerobic biomass – II. Partitioning on biosolids. Wat. Res. 30(3), pp. 672-678.

Hall, T.J.; Haley, R.K.; Borton, D.L.; and Bousquet, T.M. (1996) The use of chronic bioassays in characterizing effluent quality changes for two bleached kraft mills undergoing process changes to increased chlorine dioxide substitution and oxygen delignification" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 53-67.

Heindel, T. and Monefeldt, J. (1998) Observations of the bubble dynamics in a pulp suspension using flash x-ray radiography. Tappi Journal, 81(11), (1998), pp. 149-158.

Hewitt, L.M.; Carey, J.H.; Dixon, D.G.; and Munkittrick, K.R. "Examination of Bleached Kraft Mill Effluent Fractions for Potential Inducers of Mixed Function Oxygenase Activity in Rainbow Trout" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R.

148 Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, (1996), pp. 79-94.

Holik, H. (2000) “Unit operations and equipment in recycled fiber processing” in Recycled Fiber and Deinking, L. Gottsching and H. Pakarinen (ed.), Fapet Oy, Helsinki, p. 93.

Horning II, W.B. and Weber, C.I. (1985) Fathead Minnow (Pimephales promelas) Embryo Larval Survival and Teratogenicity Test Method 1001.0, in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA Technical Report No. EPA/600/4-85/014, pp. 42-57.

Horning W.B. and Weber C.I. (1985) Ceriodaphnia Survival and Reproduction Test Method 1002.0 in Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms. EPA Technical Report No. EPA/600/4-85/014, pp. 58-75.

Hutchins F.E. (1979) Toxicity of pulp and paper mill effluent: a literature review. U.S. EPA Report EPA-600/3-79-013.

Kemeny T.E. and Banerjee S. (1997) Relationships among effluent constituents in a bleached kraft pulp mill Water Res., 31, pp. 1589-1594.

Kemeny, T.E. and Banerjee, S. (1996) Correlations among contaminant profiles in mill process streams and effluents, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 151-158.

Kennedy, C.J.; Sweeting, R.M.; Johansen, J.A; Farrell, A.P.; and McKeown, B.A. (1996) Lethal and sublethal effects of chlorinated resin acids and chloroguaiacols in rainbow trout, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 391- 400.

Kukkonen J. and Oikari A. (1987) Effect of aquatic humus on accumulation and acute toxicity of some organic micropollutants. Sci. Total Environ. 62, pp. 399-402.

LaFleur, L.E. (1996) Sources of pulping and bleaching derived chemicals in effluents, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 21- 31.

Leach J.M. and Thakore A.N. (1976) Toxic constituents in mechanical pulping effluents. Tappi J. 59(2), pp. 129-132.

149 Leach J.M., Mueller J.C. and Walden C.C. (1976) Identification and removal of toxic materials from kraft and groundwood pulp mill effluents. Process Bioch 11(1), pp. J7-J10.

Leach J.M., Mueller, J.C. and Walden, C.C. (1977) Biodegradability of toxic compounds in pulp mill effluents. Transactions of the technical section CPPA, 3(4), pp. TR126-TR130.

Leach, J.M. and Thakore A.N. (1978) Compounds toxic to fish in pulp mill waste streams. Progress in Water Technology, 9(4), pp. 787-798.

Leach, J.M. and Thakore, A.N. (1976) Toxic constituents in mechanical pulping effluents. Tappi J. 59(2), pp. 129-132.

Lehtinen, K. (1996) Biochemical responses in organisms exposed to effluents from pulp production: Are they related to bleaching? in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 359-368.

Levich, V.G. (1962) Physicochemical hydrodynamics. Prentice-Hall, Englewood Cliffs, N.J.

Liss S.M. and Allen D.G. (1992) Microbiological study of a bleached kraft pulp mill aerated lagoon. J Pulp Paper Sci, 18, pp. J216-221.

Liss S.M., Bicho P.A. and Saddler J.N. (1997) Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview. Can. J. Microbiol., 75, pp. 599-611.

Liu, H., Lo, S., and Lavallée, H. (1996) Mechanisms of removing resin and fatty acids in CTMP effluent during aerobic biological treatment. Tappi Journal, 79, pp. 145-154.

Liver, S.F. and Hall, E.R. (1996) Interactions of resin acids with aerobic and anaerobic biomass – I. Degradation by non-acclimated inocula. Wat. Res. 30(3), pp. 663-671.

Mahmood, T. and Banerjee, S. (1999) Sources and fate of TRS compounds in a pulp mill ASB. Water Sci. and Tech. 40(11), pp. 289-295.

Makris, S, P., and Banerjee, S. (2002) Fate of resin acids in pulp mill secondary treatment systems. Water Research, 36, pp. 2878-2882.

Manahan, S.E. (1994) Toxicological chemistry, in Environmental Chemistry, sixth edition, Lewis Publishers, Boca Raton, FL, pp. 649-655.

McKague A. B., Chew W., Zhu S., and Reeve, D. W. (1998) Compounds identified in effluents from the bleaching of wood pulp, in Proceedings of the International Pulp Bleaching Conference. Helsinki, pp. 205–212. 150 McLeay, D.J., Walden, C.C. and Munro, J.R. (1979) Influence of dilution water on the toxicity of kraft pulp and paper mill effluent, including mechanisms of effect," Wat Res 13, pp. 151-158.

McLeay D.J., Walden C.C., and Munro J.R. (1979) Effect of pH on toxicity of kraft pulp and paper mill effluent to salmonid fish in fresh and seawater. Wat Res 13, pp. 249-254.

Meylan, W.M. and Howard, P.H. (1995) Atom/fragment contribution method for estimating octanol-water partition coefficients. J. Pharm. Sci. 84, pp. 83-92.

Morck R., Jansson M.B. and Dahlman O. (2000) Resinous compounds in effluents from pulp mills, in Pitch Control, Wood resin and Deresination, E.L. Back and L.H. Allen (ed.), Tappi Press, Atlanta, GA.

Mueller, J.C., Ng, K.S., and Walden, C.C. (1973) Detoxification of kraft mill effluents by foam separation. Pulp & Paper Canada 74(5), pp. 119-123.

Mueller, J.C.; Ng, K.S.; and Walden, C.C. (1974) Process parameters of foam detoxification of kraft effluent. Pulp & Paper Canada, 75(7), pp. 101-106.

Muir D.C.G. and Servos M.R. (1996) Bioaccumulation of bleached kraft pulp mill related organic chemicals by fish, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 283-296.

Munoz M.J., Castano A., Blazquez T., Vega M., Carbonell G., Ortiz J.A., Carballo M., and Tarazona J.V. (1994) Toxicity identification evaluations for the investigation of fish kills: a case study. Chemosphere 29(1), pp. 55-61.

National Council for Air and Stream Improvement (1989) Procedures for the analysis of resin and fatty acids in pulp mill effluents. Technical Bulletin No. 501.

National Council for Air and Stream Improvement. (1997) NCASI Distributes RFP for Environmental Research Under Agenda 2020. NCASI Bulletin Board, 23(11).

Null, H.R. (1987) Selection of a separation process, in Handbook of Separation Process Technology, R.W. Rousseau (ed.), John Wiley & Sons, New York, NY, pp. 982-994.

Nyren, V. and Back, E. (1958) The ionization constant, solubility product and solubility of abietic and dehydroabietic acid. Acta chemica Scandinavica, 12(7), pp. 1516-1520.

O’Connor B.I., Kovacs T.G. and Voss R.H. (1992) The effect of wood species composition on the toxicity of simulated mechanical pulping effluents. Environ. Toxicol. Chem. 11, pp. 1259- 1270. 151 Oliveira, J.F., Saraiva, S.M., Pimenta, J.S., and Oliveira, A.P.A. (2001) Kinetics of pyrochlore flotation from araxa mineral deposits. Minerals Eng. 14(1), pp. 99-105.

Peng, G. and Roberts, J.C. (2000) Solubility and toxicity of resin acids, Wat. Res. 34(10), pp. 2779-2785.

Perry, R.H. and Green, D. (1984) Adsorptive-bubble separation methods, in Perry's Chemical Engineer's Handbook, 6th Edition, McGraw-Hill, Inc., New York, pp. 1760-1766.

Personal communication on December 10, 1998 with Thomas E. Kemeny, a pulping, bleaching and environmental consultant.

Personal communication on November 23, 1998, Richard H. Sugatt, President, Ecotox Consultants, Exeter, NH.

Propst, M. and Drew, J. (1987) Tall oil soap recovery, in Tappi Kraft Recovery Operations Seminar Proceedings, Tappi Press, Atlanta, GA, pp. 109-112.

Rand, G.M. and Petrocelli, S.R. (1985) Fundamentals of aquatic toxicology - methods and applications, Hemisphere Publishing Corporation, Washington, D.C.

Ribo, J.M. and Kaiser, K.L.E. (1983) Effects of selected chemicals to photoluminescent bacteria and their correlations with acute and sublethal effects on other organisms. Chemosphere 12(11/12), pp. 1421-1442.

Rubinstein, J.B. and Samygin V.D. (1998) Effect of particle and bubble size on flotation kinetics, in Frothing in Flotation II, J.S. Laskowski, and E.T. Woodburn (ed.), Gordon and Breach Science Publishers, Amsterdam, Netherlands.

Servos, M.R. (1996) Origins of effluent chemicals and toxicity: recent research and future directions, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 159-166.

Severtson, S.J. and Banerjee S. (1996). Sorption of chlorophenols to wood pulp. Environ. Sci. Technol. 30, pp. 1961-1969.

Severtson, S.J. and Banerjee S. (2001). Dual reactive domain model for sorption of aqueous organics by wood fiber, J. Colloid Interfacial Sci., in press.

Shah, Y.T., Kelkar, B.G., and Godbole, S.P. (1982) Design parameters estimations for bubble column reactors. AIChE Journal, 28(3), 353-379.

152 Shaw, D.J. (1992) Surface & Colloid Chemistry, 4th Edition, Butterworth-Heinemann, Boston, MA, pp. 84-93.

Sjostrom, E. (1993) “Extractives” in Wood Chemistry: Fundamentals and Applications, 2nd ed., Academic Press, Inc., San Diego, pp. 92-107.

Somasundaran, P. and Ananthapadmanabhan, K.P. (1987) Bubble and foam separation – ore flotation, in Handbook of Separation Process Technology, R.W. Rousseau (ed.), John Wiley & Sons, New York, NY, pp. 775-803.

Ström G. (2000) Physio-chemical properties and surfactant behavior, in Pitch Control, Wood Resin and Deresination, E.L. Back and L.H. Allen (ed.), Tappi Press, Atlanta, GA.

Stromberg, L.; Morck, R.; de Sousa, F; and Dahlman, O. (1996) Effects of internal process changes and external treatment on effluent chemistry, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 3-19.

Suntio, L.R., Shiu, W.Y., Mackay, D. (1988) A review of the nature and properties of chemicals present in pulp mill effluents. Chemosphere 17, pp. 1249-1290.

Sweet L.I., Travers, D.F., and Meier, P.G. (1997) Chronic toxicity evaluation of wastewater treatment plant effluents with bioluminescent bacteria: a comparison with invertebrates and fish. Environ. Toxicol. and Chem., 16(10), pp. 2187–2189.

Szatkowski, M. and Freyberger, W. L. (1985) Kinetics of flotation with fine bubbles. Trans Inst Min Metall Sect C 94, pp. 61-70.

Technical Association of the Pulp and Paper Industry. (1992) Tappi Test Method T236-cm-85, TAPPI Press, Atlanta, GA.

Tay, S. (2001) Effect of dissolved and colloidal contaminants in newsprint machine white water on water surface tension and paper physical properties, Tappi Journal, 84(8).

U.S. EPA website: http://cfpub.epa.gov/npdes/index.cfm, accessed on May 1, 2003.

U.S. EPA website: http://oaspub.epa.gov/enviro/ef_home2.water, accessed on June 15, 2003.

Verta M., Ahtiainen J., Nakari T., Langi A., and Talka E. (1996) The effect of waste constituents on the toxicity of TCF and ECF pulp bleaching effluents" in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 41-51.

153 Wagner, R.E. (1992) Guide to Environmental Analytical Methods. Genium Publishing Corporation, Schenectady, NY, pp. 742-795.

Walden C.C. and Howard T.E. (1981) Toxicity of pulp and paper mill effluent: a review. Pulp Paper Canada 83, pp. T143-148.

Weber, C.I. (1991) Methods for measuring the acute toxicity of effluents and receiving waters to freshwater and marine organisms. EPA Technical Report No. EPA/600/4-90-027.

Werker A.G. and Hall E.R. (1997) The influence of pH on resin acid solubility related to biodegradation kinetics of resin acid in pulp mill effluent. 1997 Environmental Conference & Exhibit Proceedings, pp. 19-26.

Werker A.G. (1998) The effect of pH on microbial activity and community structure in the biological removal of resin acids from wastewater. PhD, University of British Columbia, Vancouver.

Werker A.G. and Hall E.R. (1999) Limitations for biological removal of resin acids from pulp mill effluent. Wat. Sci. Tech. 40(11,12), pp. 281-288.

Werker A.G. and Hall E.R. (2000) The fate of a resin acid shock load in a biological system. Pulp Paper Canada 101(1), pp. 45-49.

Werker A.G., Bicho P.A., Saddler J.N., and Hall E.R. (1996) Surface tension changes related to the biotransformation of dehydroabietic acid by Mortierella Isabellina, in Environmental Fate and Effects of Pulp and Paper Mill Effluents, M.R. Servos, K.R. Munkittrick, J.H. Carey and G. Van Der Kraak (ed.), St. Lucie Press, Delray Beach, FL, pp. 139-150.

Westall J.C. (1985) Influence of pH and ionic strength on the aqueous –nonaqueous distribution of chlorinated phenols. Environ. Sci. & Technol., 19, pp. 193-197.

Williams C.L., Mahmood T., Corcoran H., Zaltzmann M.E., and Banerjee S. (1997) Tracing the efficiency of secondary treatment systems. Environ. Sci. Technol., 31(11), pp. 3288-3292.

Yalkowsky S. H. and Banerjee S. (1992) Aqueous Solubility. Methods of Estimation for Organic Compounds, Dekker, New York.

Yu Z. and Mohn, W.W. (2002) Bioaugmentation with the resin acid-degrading bacterium Zooglea resiniphila DhA-35 to counteract pH stress in an aerated lagoon treating pulp and paper mill effluent. Water Research 36(11), pp. 2793-2801.

Zajic J.E., Berk D., and Behie L.A. (1979) Foam fractionation of spent sulphite liquor, Part I: Separation of surfactants. Canadian Journal of Chemical Engineering 57(6), pp. 321-332. 154 Zanella A. (1983) Effect of pH on acute toxicity of dehydroabietic acid and chlorinated dehydroabietic acid to fish and Daphnia. Bull. Environm. Contam. Toxicol., 30, pp. 133-140.

Zender J.A., Stuthridge T.R., Langdon A.G., Wilkins A.L., Mackie K.L. and MacFarlane P.N. (1994) Removal and transformation of resin acids during secondary treatment at a New Zealand bleached kraft pulp and paper mill. Wat. Sci. Tech., 29(5,6), pp. 105-121.

155

156