Bleached Kraft Pulp Mill Effluent Research Articles

Dissociation constants of chloroguaiacols in water: A comparison of measured and predicted values

AbstractChloroguaiacols are common components of bleached‐kraft pulp mill effluent known to bioaccumulate in aquatic organisms and to sorb on particulate material and sediments. Ionization properties of the chloroguaiacols must be known in order to explain their sorptive behavior in aquatic systems. To obtain this information, thermodynamic acid dissociation constants (pKa) of guaiacol (o‐methoxyphenol) and nine chloroguaiacols have been determined by spectrophotometric methods. These experimental pKa values have been compared with literature values, values predicted by the Hammett equation, and predictions by quantum chemical calculations using MOPAC 6.0 with AM1 and MNDO Hamiltonian operators. Experimental and predicted acidities were strongly correlated, and the correlation equations obtained have been used to calculate pKa values for those chloroguaiacols that were unavailable for experimental measurement.

Utility of field-based artificial streams for assessing effluent effects on riverine ecosystems

Experimentation using field-based artificial streams provides a promising, complimentary approach to biomonitoring assessments because artificial streams provide control over relevant environmental variables and true replication of treatments. We have used large and small artificial stream systems, based in the field, to examine the effect of treated bleached kraft pulp mill effluent (BKME) on the benthos of three large rivers in western Canada. Under natural regimes of temperature, water chemistry, and insolation, these artificial streams provide current velocities and substrata to food chains or food webs that are representative of those in the study river. With these tools we have shown that BKME stimulated mayfly growth in the Thompson River above that which could be accounted for by fertilization of their algal food supply. In contrast, moulting frequency was inhibited at high BKME concentrations. Results from artificial streams also indicate that increased algal biomass and abundances of benthic communities downstream of BKME outfalls were induced by nutrient enrichment from the effluent. BKME treatments did not change diatom species richness in the Fraser River, or diatom species diversity in either the Athabasca or Fraser Rivers. Artificial streams provide a means of understanding the mechanisms of stressor effects over a continuum ranging from single stressor effects on specific taxa to the effects of multiple stressors on communities and ecosystems. Because riverside deployment provides environmental realism within a replicated experimental design, this approach can (i) address questions that cannot be examined using laboratory tests or field observations, (ii) improve our mechanistic understanding of stressor effects on riverine ecosystems, and (iii) can contribute directly to the development, parameterization, and testing of models for predicting ecosystem-level responses.

Biological Dechlorination of Model Organochlorine Compounds in Bleached Kraft Mill Effluents

Models of organochlorine compounds present in bleached kraft pulp mill effluent, with well-defined structure, can be used to provide information on the relationship between their chemical structure and their behavior toward biological dechlorination. The biological dechlorination of three monomeric model compounds, 4-methyl-5-chloromuconolactone monomethyl ester (MCME), 2-chloro-3-methylmuconolactone (CMML), and 3-chloro-4-methylcatechol (CMCA), and a dimeric model, 2-(4‘-methyl-2‘-muconylmethyl)-3-chloro-4-methylmuconic acid dilactone (CMDL), were studied. The first two monomers are products of simulated bleaching reactions (sequentially with ClO2 and NaOH) using a monomeric model compound of residual lignin, 4-methylguaiacol (MG), and are considered to be monomeric models of organochlorines in the ClO2 bleachery effluents. Similarly, the dimer model is a product of a dimeric lignin model reacting with ClO2 and NaOH and is considered to be a model of organochlorines of higher molecular weight. CMCA was chosen as a model compound for the phenolic portion in the effluent. It was found that MCME and CMDL do not undergo biological dechlorination. CMML did not dechlorinate in the absence of biomass for over 35 days, but it was dechlorinated by biomass from a pulp mill activated sludge system within 8 days. CMCA was found to be chemically unstable and rapidly dechlorinates when dissolved in water. The recalcitrance of MCME and CMDL to biological dechlorination is postulated to result from the fact that they both possess structural features that represent a dead-end intermediate of the ortho-cleavage pathway that is common to many aerobic bacteria.

Effects of Pulp and Paper Mill Effluent (BKME) on Physiology and Biochemistry of the Roach (Rutilus rutilus L.)

The effects of bleached kraft pulp and paper mill effluent (BKME) on the roach (Rutilus rutilus L.) were studied under experimental and natural field conditions. In the acute experiment (72 h exposure to the concentrated BKME), the roach suffered from a general stress syndrome, characterized by a significant increase of cortisol and blood glucose, as well as a significant decrease of leucocrit and total plasma protein. In three weeks' exposure in a polluted and an unpolluted lake and in fish caught from the same lakes, the more specific effects of BKME treatments appeared. During the three weeks' exposure, slight hyperglycaemia as well as a decrease in a transaminase activity (GPT) and increase in the plasma total protein concentration of the fish occurred in the polluted lake. Fish caught from the polluted lake exhibited lower values of haematocrit, transaminases (GOT and GPT), and calcium concentration plus a higher chloride concentration in the plasma than in the unpolluted lake. The differential leukocyte counts also showed slight differences: Fewer lymphocytes and more granulocytes were found in roach from polluted waters. The morphology of the red blood cells in the roach from polluted lakes had more elongate erythrocytes with a longer major axis and a shorter minor axis than in fish from the polluted lake. The possibilities of determining the origin of fish based on their erythrocyte morphology is discussed.

Immunotoxicity studies in mink (Mustela vison) chronically exposed to dietary bleached kraft pulp mill effluent.

The immunotoxic potential of bleached kraft pulp mill effluent (BKME) to cell-mediated immunity in mink (Mustela vison) was investigated October 1993 through May 1994. For 26 weeks, 20 mink were fed a diet based upon fish caught within 6 km downstream of a bleached kraft mill in Saskatchewan, Canada. Water for this group contained 25% softwood-run BKME. Twenty control mink were fed nutritionally matched diets based upon fish from lakes receiving no municipal or industrial effluent and tap water. Using in vitro and in vivo immunotoxicity assays, the proliferative response of mink peripheral blood mononuclear cells (PBMC) to mitogens was optimal, at 72 hr with 10 micrograms/ml Concanavalin A, 1/80 dilution pokeweed mitogen, and 1/80 dilution phytohemagglutinin. Bacterial cell wall Escherichia coli lipopolysaccharide did not stimulate mitosis of the mink PBMC. No difference (P < 0.05) in PBMC proliferation was seen between the control and BKME-exposed mink with any of the mitogens used. Delayed type hypersensitivity (DTH), a cell mediated response, was assessed in mink vaccinated with live bacille Calmette-Guérin (BCG) and then challenged by intradermal toe web injection with 200 micrograms of sonicated BCG approximately 6 weeks later. The DTH response in the BKME-exposed mink was impaired based upon assessment using skin thickness measurements, histopathological assessment and image analyzer technology. This decreased response is evidence for suboptimal immune function associated with BKME exposure, which could affect the competitive fitness of piscivorous mammals naturally exposed to BKME.

Capture and Confinement Stress in White Sucker Exposed to Bleached Kraft Pulp Mill Effluent

This study evaluates the effects of handling and confinement stress and a 3-day recovery period on a number of biochemical parameters used to monitor exposure of fish to bleached kraft mill effluent (BKME). Plasma was collected at four times of the day from male and female white sucker subjected to four levels of handling stress during their spawning migration at a BKME and a reference site. Indicators of a general response to stress (plasma cortisol, glucose, lactate, and total protein) and of reproductive fitness (plasma testosterone, 11-ketotestosterone, and 17β-estradiol) were measured. With the exception of 17β-estradiol in females, all of the parameters measured varied with time of day and stress level. The general stress indicators ranged from being highly to marginally responsive to handling and confinement stress and were inconsistent in terms of indicating a site difference. The reproductive steroids were moderately responsive to stress and gave the most consistent site difference with testosterone and 11-ketotestosterone levels reduced in BKME-exposed fish under low levels of stress. There was limited evidence for recovery from capture, handling, and transport in the spring for plasma cortisol, lactate, and 17β-estradiol at the BKME site, plasma glucose at the reference site, and plasma testosterone at both sites. Fish were also more responsive to an additional acute stress on Day 1 and Day 3 of recovery compared to that on Day 0. This study emphasizes the need for standardized methods in field collections and sampling with the least amount of stress possible, and suggests that holding white sucker for 1 or 3 days does not allow them to recover from the stress of capture.

An Epidemiological Evaluation of the Biochemical Basis for Steroid Hormonal Depressions in Fish Exposed to Industrial Wastes

Our earlier work showed that exposure to bleached kraft pulp mill effluent resulted in a number of reproductive alterations in white sucker including depression of circulating sex steroid hormone levels. Further studies demonstrated that reductions in the steroid biosynthetic capacity of the ovarian follicle were responsible for these changes. In this study an epidemiological approach was used to evaluate whether fish (white sucker and brown bullhead) exposed to different classes of organic compounds (non-chlorinated pulp mill effluent and polycyclic aromatic hydrocarbons) exhibit comparable alterations in reproductive function (reduced gonadal size, reductions in circulating steroid levels and depressed steroid biosynthetic capacity). The criteria of probability, strength of association, and consistency with respect to time were satisfied with respect to these reproductive alterations. The responses observed did not satisfy the criteria of specificity, or consistency with respect to different people and were indeterminate for the criteria of prediction, time order, consistency with respect to different places, species and contaminant as well as for coherence. In conclusion, changes in reproductive performance represents a common response in fish exposed to pulp mill effluent and other organic contaminants, but the biochemical basis for steroid hormone depression in fish associated with organic contaminant exposure is not consistent enough to allow generalizations at this time.

Evidence for a Reduction of 2,3,7,8-TCDD Toxic Equivalent Concentrations in White Sucker ( Catostomus commersoni) Exposed to Bleached Kraft Pulp Mill Effluent, Following Process and Treatment Improvements

Over a 4-year period from 1990 to 1993, the H4IIE bioassay was used to measure 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentrations (TECs) in the liver tissue of white sucker exposed to bleached kraft mill effluent. During two of the sampling periods, the H4IIE bioassay-derived TECs (BD-TECs) were compared directly with BD-TECs measured by a similar bioassay using a rainbow trout liver cell line (RTL-W1). From 1989 to 1993, chemistry-derived TECs (CD-TECs) were calculated directly from measured polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) concentrations in liver tissue. Chemistry-derived TECs were compared to bioassay-derived TECs using toxic equivalent factors (TEFs) developed for these systems. During the study period, the pulp mill began secondary treatment of effluent and increased the substitution of chlorine dioxide for molecular chlorine during bleaching. Significant reductions in H4IIE BD-TECs and CD-TECs were observed in liver tissue of both male and female white sucker during summer and fall sampling periods but not during spring sampling periods. Process and treatment improvements at this particular bleached kraft pulp mill appear to have been successful at reducing the levels of PCDDs and PCDFs found in white sucker exposed to the effluent. Despite the decreases in TECs, relative mixed function oxygenase (MFO) induction in the exposed white sucker did not decrease over the study period, suggesting the PCDDs and PCDFs are currently not the dominant MFO-inducing compounds in the effluent of this mill.

Mutagenicity of cyclophosphamide and kraft mill effluent and sediment on the eel Anguilla anguilla L.

The sister chromatid exchange (SCE) assay in A. anguilla L. gills has been developed in our laboratory to assess the mutagenic activity of compounds present in brackish water environments contaminated by industrial effluents. The sensitivity of the test was assessed by performing mutagenic treatment for 72 h with a standard compound — cyclophosphamide (CP) (6.25, 12.5, 25, 50, 100 mg/l). This species exhibits a dose response to CP at the concentration range 6.25–100 mg/l. A 100-mg/l dose of CP increased the rate of SCE per metaphase plate from a base line frequency 0.23 SCE's per metaphase plate up to 3.4 SCE's per metaphase plate. The mutagenic effect of the bleached kraft pulp mill effluent (BKPME) and its sediment was also tested in Anguilla anguilla L., using the sister chromatid exchange assay (SCE). The results showed an increase in the number of SCE's per metaphase plate in the eel, A. anguilla L., exposed to the 75% BKPME compared with the SCE's in BKPME sediment plus BKPME (S + BKPME) and with BKPME sediment plus clean tap water exposed eels (S + W). However, the number of SCE's per metaphase plate in A. anguilla L. exposed to 75% BKPME is lower than in the standard cyclophosphamide (CP) exposed eels. The SCE frequency was: CONTROL < S + W < + BKPME < BKPME < CP.

The Phytoestrogen β-Sitosterol Alters the Reproductive Endocrine Status of Goldfish

There is growing awareness that chemicals in the environment may function as hormone mimics and affect endocrine function in wildlife. In this study, the effects of β-sitosterol, a phytoestrogen present in high concentration in bleached kraft pulp mill effluent (BKME), on reproductive fitness of goldfish were investigated. Plasma reproductive hormone levels were measured in male and female goldfish on Day 4 following two intraperitoneal injections of β-sitosterol or an oxidized sitosterol preparation. In some experiments, plasma hormone levels were also measured after fish were injected with Ovaprim, which contains a superactive analog of salmon GnRH and the dopamine receptor antagonist domperidone and leads to increased secretion of gonadotropin (GtH)-II (LH-type GtH). Plasma testosterone (T) and 11-ketotestosterone levels in males and T and 17 β-estradiol levels in females were significantly decreased in β-sitosterol-treated fish on Day 4 and 24 hr after an injection of Ovaprim. Plasma GtH-II levels were elevated in male fish treated with β-sitosterol on Day 4 and further increased in response to Ovaprim, suggesting that reduced plasma steroid levels were not due to effects on pituitary function. In other studies, testes pieces from β-sitosterol-treated goldfish produced reduced levels of T and pregnenolone in vitro both basally and in response to the GtH-II agonist human chorionic gonadotropin (hCG) when compared to the testes from control fish. Basal and hCG-stimulated pregnenolone and hCG-stimulated T were reduced in follicles from β-sitosterol-treated fish; however, basal T production was not different from controls. These results suggest that β-sitosterol reduces the gonadal steroid biosynthetic capacity through effects on cholesterol availability or the activity of the side chain cleavage enzyme P 45OSCC. These findings raise the possibility that β-sitosterol could be a contributing factor to the reproductive dysfunction observed in fish exposed to BKME.

Stimulation of increased short‐term growth and development of mayflies by pulp mill effluent

AbstractTo determine the food‐dependent effects of biologically treated, bleached‐kraft pulp mill effluent on mayfly (Baetis tricaudatus Dodds) growth and development, mayflies were exposed to effluent for 2 weeks within artificial streams arranged in a 2 × 3 factorial design (two periphyton food levels ‐ low, high; three concentrations ‐ control river water, 1% effluent, 10% effluent). Although survival was not affected, the effluent had a significant stimulatory effect on growth (resulting in 20 to 50% greater body weights) and development of the wing pads. Furthermore, the initial growth and development trajectories suggest that effluent‐exposed mayflies may emerge sooner and at a larger size than nonexposed individuals. A key result was that the stimulatory effects occurred within both the low‐ and high‐food treatments. Thus, the effluent‐exposed mayflies grew‐faster than even the high‐food control animals, which already had access to more food than they could eat throughout the experiment. This shows that the stimulatory effect of the effluent on the mayflies involved more than just an increase in food‐availability due to enhanced algal growth in response to nutrients in the effluent. Three possible mechanisms for this growth‐enhancement effect are that the effluent (a) increased the nutritive value of the food, (b) enhanced the palatability of the periphyton, inducing increased mayfly feeding, and/or (c) directly stimulated increased mayfly growth via hormonal or other growth‐stimulation effects. Further work is required to determine whether the growth stimulation occurred at the expense of future reproductive output.

Second‐round interlaboratory comparison of hepatic ethoxyresorufin‐O‐deethylase activity in white sucker (Catostomus commersoni) exposed to bleached‐kraft pulp mill effluent

AbstractLivers were collected from six male and six female white sucker (Catostomus commersoni) at both a bleached‐kraft pulp mill effluent (BKME)‐exposed site and a reference site during the 1992 spring spawning migration. A semistandardized methodology for 7‐ethoxyresorufin‐O‐deethylase (EROD) analysis was proposed that featured similar physical and chemical conditions yet allowed for different instrumentation and techniques. Postmitochondrial supernatants (PMSs) were analyzed for EROD activity by 14 laboratories, and repeat EROD analyses were performed within one laboratory to estimate within‐laboratory variability. All laboratories found significantly higher levels of EROD activity (approximately threefold) in males from the BKME‐exposed site; only 5 of 14 laboratories found significantly higher levels in exposed females. Data from three labs were dropped from the analysis because of outlying values. The mean coefficient of variation (C.V.) for the remaining 11 laboratories was 34.7%, which was not significantly different from the C.V. determined for six analyses by one technician (28.4%). The mean C.V. for five analysts within one laboratory was significantly lower (16.4%) than either of the former values. There was no difference in absolute values or the variability of microplate and conventional EROD assay data. Analysis of Bradford and Lowry protein data showed that both assays have low variability (C.V.s = 16.8 and 17.4%, respectively); these two techniques produced very similar estimates of protein content. Immunochemical analysis demonstrated a significant correlation existed among microsomal P4501A concentration and EROD activity. Sources of commercially available resorufin standard were tested, and the mean molar extinction coefficient was 54.0 ± 1.1 cm−1 mM−1.

Physiological Toxicity of Low-Chlorine Bleached Pulp and Paper Mill Effluent on Whitefish ( Coregonus lavaretus L. s.l.): A Laboratory Exposure Simulating Lake Pollution

In order to validate previous field observations by the authors on whitefish, Coregonus lavaretus L. s.l., a 30-day laboratory experiment with concentrations (0, 1.3, 2.3, 3.5, and 7 vol%) of bleached kraft pulp and paper mill effluent (BKME) simulating those occurring in a polluted lake was conducted. Chlorine dioxide had almost entirely replaced chlorine gas in the bleaching of pulp. As a consequence, the concentrations of adsorbable organic halogens and chlorinated phenolics (CPs) in BKME were significantly lowered compared to earlier studies. This reduction was also seen in the concentrations of CPs in the bile and CPs and extractable organic halogens in the intestinal lipids: the concentrations were low and did not depend on the dilution of BKME. In contrast, the resin acid content of bile decreased with decreasing BKME concentration. The growth of fish was speeded up in all BKME concentrations. However, at the highest BKME concentration (7 vol%) the increase was lowest. The induction of hepatic ethoxyresorufin O-deethylase (EROD) activity revealed strong dose-response relationship with BKME. At 3.5 vol% BKME (corresponding to a distance of 3.3 km from the mill sewer in the field) the EROD activity increased 12-fold. There was a tendency for lower activity of uridinediphosphate glucuronosyltransferase in the liver, but the decrease (34%; P < 0.05) was statistically significant only at 7 vol% BKME. The activity of liver glutathione S-transferase remained unchanged. All dilutions of BKME significantly depressed the concentrations of plasma immunoglobulin M (IgM). Erythrocytic concentrations of nucleotide triphosphates decreased and of sodium increased as the BKME concentration increased. Also some other blood parameters (hematocrit, hemoglobin, plasma glucose, and aspartate aminotransferase) were changed in all BKME exposures, although without obvious dependence on effluent concentration. In conclusion, there was a good agreement between field studies and laboratory experiments using BKME concentrations occurring in the field, confirming close or similar causes for responsive toxicity endpoints.

Hepatic 7-ethoxyresorufin-O-deethylase activity, plasma steroid hormone concentrations, and liver bioassay-derived 2,3,7,8-TCDD toxic equivalent concentrations in wild white sucker (Catostomus commersoni) caged in bleached kraft pulp mill effluent

Prespawning male white sucker (Catostomus commersoni), captured near Jackfish Bay, Lake Superior (exposed to bleached kraft pulp mill effluent (BKME)), and Mountain Bay (reference) were caged in the BKME receiving area for 2, 4, and 8 d. Initially, the hepatic 7-ethoxyresorufin-O-deethylase activity was similar in fish from both BKME and reference sites and, upon BKME exposure, increased 20-fold at both sites after 2 d. The H4IIE cell culture bioassay was used to measure 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentration (TEC) in sucker liver extracts. H4IIE bioassay-derived TECs from Jackfish Bay sucker showed no significant treatment differences; combined TECs for all treatments averaged 51.1 pg∙g−1. Mountain Bay sucker liver TECs were initially significantly less (4.64 pg∙g−1) than the Jackfish Bay TECs but did show a significant, fivefold increase when fish were exposed to effluent. Mountain Bay and Jackfish Bay 8-d BKME-exposed fish showed no uptake of TECs calculated from directly measured polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) during this exposure. The results suggest that PCDDs and PCDFs are not responsible for the mixed function oxidase induction observed. Handling stress caused rapid reduction of the plasma steroids testosterone and 11-ketotestosterone, confounding any possible BKME effect.

Characterization of odorous compounds from bleached kraft pulp mill effluent

Odour compounds in extracts of bleached kraft pulp mill effluent (BKME) have been characterized by olfactory gas chromatography (OGC) and gas chromatography-mass spectrometry. A variety of sulfury odours was detected by OGC in addition to woody and pulp mill-like odours. Three sulfur compounds were identified by comparison of retention times and partial mass spectra with authentic standards: dimethyl disulfide, 3-methylthiophene and thioanisole (methyl phenyl sulfide). Typical concentrations in BKME were 1, 0.05, and 0.5 μg/l, respectively. Their odour intensity is relatively low and they were not detected by OGC. Dimethyl trisulfide was tentatively identified by comparison of its partial mass spectrum with a literature (library) spectrum. Its concentration in BKME was estimated at 0.5-2 μg/l. It corresponded to a skunky odour in the OGC profiles. Efforts to identify another odour peak, eluting just after 3-methylthiophene, with a pronounced alkyl sulfide odour were unsuccessful.

Characterization of odorous compounds from bleached kraft pulp mill effluent

Odour compounds to extracts of bleached kraft pulp mill effluent (BKME) have been characterized by olfactory gas chromatography (OGC) and gas chromatography-mass spectrometry. A variety of sulfury odours was detected by OGC in addition to woody and pulp mill-like odours. Three sulfur compounds were identified by comparison of retention times and partial mass spectra with authentic standards: dimethyl disulfide, 3-methylthiophene and thioanisole (methyl phenyl sulfide). Typical concentrations in BKME were 1, 0.05, and 0.5 µg/l, respectively. Their odour intensity is relatively low and they were not detected by OGC. Dimethyl trtsulfide was tentatively identified by comparison of its partial mass spectrum with a literature (library) spectrum. Its concentration in BKME was estimated at 0.5-2 µg/l. It corresponded to a skunky odour in the OGC profiles. Efforts to identify another odour peak, eluting just after 3-methylihiophene, with a pronounced alkyl sulfide odour were unsuccessful.

Characterization of Chlorolignins in Bleached Kraft Pulp Mill Effluents Using Elemental Analysis and Fingerprinting by CuO Oxidation And Hplc

Abstract Elemental analyses and chemical degradation techniques were applied to characterize lignin compounds in different stages of the chlorine bleaching process and in total mill effluent. Ultrafiltration was used for separation of chlorolignins into three nominal molecular weight fractions. Alkaline CuO oxidation products were analyzed by HPLC with diode array detection. Major compounds were identified by reference to authentic compounds. For comparison, native lignins (MWL), kraft lignins, and humic substances were studied as well. The oxygen, carbon and organic chlorine contents were closely similar in the various mill samples and their fractions. In all mill samples, vanillin and 6-chlorovanillin were the most abundant CuO oxidation products. There were no essential differences between the effluents before and after the activated sludge treatment. The results indicate the stability of chlorolignins during the bleaching and in particular during the purification. The fingerprint CuO/HPLC and elementa...

Suitability of carboxylated porphyrin profiles as a biochemical indicator in whitefish (Coregonus clupeaformis) exposed to bleached kraft pulp mill effluent

AbstractThe hepatic carboxylated porphyrin profile was studied in whitefish exposed to bleached kraft pulp mill effluent (BKME). The distribution of the porphyrins was different between the samples from the BKME and the reference site, and fish exposed to BKME contained higher amounts of highly carboxylated porphyrins (HOP). The ratios of HCP to protoporphyrin, and coproporphyrin to protoporphyrin, were also significantly different between the two groups. In addition, the cytochrome P‐450 activity, liversomatic index, and gonadosomatic index were measured and compared with the prophyrin profile. The results suggest that BKME could inhibit porphyrinogen decarboxylases, and the porphyrin profile is useful as a biochemical indicator for identification of BKME exposure. © 1994 by John Wiley &amp; Sons, Inc..

A Field Study of Environmental Impacts at a Bleached Kraft Pulp Mill Site on the Baltic Sea Coast

The rate of technical development in bleaching of chemical pulp and the upgrading of process control and wastewater treatment systems in the pulp industry have been extremely rapid over the past few years. When assessing the environmental impacts of bleached kraft pulp mill effluents (BKMEs), it is therefore more important than ever to carefully characterize the bleaching process, the composition of the treated effluent, and the degree of exposure of sensitive target organisms in the receiving water body. These requirements have not always been fulfilled in previous reports on biological effects of BKMEs in Scandinavia. This work presents the results of a comprehensive field study of the impacts of a 350,000-tonne kraft mill, bleaching softwood and hardwood pulp in campaigns according to the sequence O(D25,C70+D5)(EOP)D(EP)D. The effluent is treated in an aerated lagoon with a mean retention time of 8-9 days, practically eliminating chlorate and resin acids, and reducing the discharge of adsorbable organic halogen (AOX) to an average of 1 t/day (1.3 and 0.4 kg/ADt for softwood and hardwood, respectively). The treated effluent is discharged through a 1.3-km-long diffuser, at a water depth of 9-12 m, into a well ventilated coastal area, giving a 1000-fold dilution within 3-4 km from the diffuser. The actual exposure of the coastal ecosystem to BKME components was determined by analysis of extractable organic chlorine in suspended solids and of conjugates of chlorophenolics in the bile of feral perch. Despite a major damage to the benthic communities that occurred about 10 years ago, and was due to large chlorate discharges at the time, no direct detrimental effects on benthic flora and fauna could be ascribed to the present BKME discharge. Instead, a clear recovery of the Fucus community, although not yet completed, could be demonstrated. Studies of the composition, abundance and biomass of the fish community, the recruitment and survival of fish fry, and the physiological status of perch, using a set of biomarkers, revealed that even in the most BKME-exposed area, only minor effects were detected. These effects were related to eutrophication/enrichment rather than to the action of toxic substances. The general effect picture, thus, was essentially of a different type than the one recorded in previous studies of mills, which used older technology and less effective process and effluent treatment control, and which were discharging into enclosed, shallow bays of the Baltic Sea.

Chlorinated anisoles and veratroles in a Canadian river receiving bleached kraft pulp mill effluent. Identification, distribution, and olfactory evaluation

One chlorinated anisole and three chlorinated veratroles have been identified in extracts of Athabasca River water collected in the winter downstream from a bleached kraft pulp mill effluent. Their potential for causing off-flavors in the receiving waters was evaluated. The average concentration of 2,4,6-trichloroanisole was about 1 ng/L, close to the odor threshold concentration in water. The average concentrations of 4,5-dichloroveratrole, 3,4,5-trichloroveratrole, and tetrachloroveratrole were 7, 7, and 1 ng/L, respectively, 2-4 orders of magnitude below their odor threshold concentrations. Chemical structure appears to be more important than volatility from water (Henry's constant) in determining odor threshold concentration