Bleached Kraft Mill Research Articles

Winter oxygen conditions in ice-covered rivers: the impact of pulp mill and municipal effluents

Depressions in dissolved oxygen (DO) commonly occur in ice-covered rivers and can be further exacerbated by anthropogenic inputs. To assess the impact of pulp mill and municipal effluents on under-ice oxygen, temporal and spatial patterns in DO were examined for the Athabasca River, Alberta, Canada. Start-up of a bleached kraft mill in 1957 was associated with the lowest late-winter (February-March) DO concentrations ever recorded. Improvements in mill technology since 1977 coincided with increases (P < 0.05) in late-winter DO concentrations at two of three downstream sites and an amelioration in both the magnitude and downstream extent of the DO sag. During recent years (1988-1993), effluent loading resulted in sag and recovery zones over small spatial scales (tens of kilometres) and also contributed to large-scale (hundreds of kilometres) linear declines in DO. A review of oxygen conditions in ice-covered rivers throughout the world likewise showed that DO concentrations decreased linearly with distance below effluent outfalls for most river reaches with effluent concentrations >1%. Our observation that depressions in DO in ice-covered rivers increase with distance downstream raises concerns about safeguarding oxygen levels in northern rivers, especially in view of increasing development in these areas.

The effects of tetrachloroguaiacol on the growth, survival, and development of the fathead minnow, Pimephales promelas.

Fathead minnow (Pimephales promelas) larvae were exposed for 7 days to tetrachloroguaiacol (TeCG), within 24 h of hatching, at concentrations of 0, 25, 50, 100, 200, 400 microg/L. No significant difference in growth or larval survival was found among treatments. Embryos, within 24 h of fertilization, were also exposed to TeCG at concentrations of 0 and 100 microg/L for 10 days. No significant difference was found between the control and treatment groups for larval survival, body length, body width, or for yolk size of the eleutheroembryos. However, a significant difference was found in the hatching success of the eggs (p = 0.05). Since fathead minnows have been known to spawn in areas close to sites that discharge bleached kraft mill effluent (BKME) which contains TeCG, into receiving waters, naturally occurring populations will likely be affected by the toxicant.

The fate of resin acids-2. The fate of resin acids and resin acid derived neutral compounds in anaerobic sediments

A sediment, sampled from a hydroelectric lake receiving a bleached kraft mill effluent discharge, was incubated anaerobically for 264 days. Both recipient and sterilised control sediments were periodically sampled and analysed to monitor the changes in resin acid composition with time. Over 264 days of incubation, the concentration of total resin derived compounds decreased by 50%. The total resin acid concentration was reduced by 50% whereas the concentration of resin derived neutrals decreased by 54%. Relative to an incubated sterile control sediment, the pimaranic acid concentration remained constant, 8-pimarenic and 8-isopimarenic acid concentrations slightly increased and pimaric, isopimaric, abietanic and secodehydroabietic acid concentrations decreased. Dehydroabietic acid was transformed to tetrahydroretene simultaneously with the transformation of labelled dehydroabietic acid to a variety of labelled products. Throughout the incubation period, the concentration of fichtelite remained constant. The concentration of retene slightly increased until the final 50 days of incubation, during which time dehydroabietin and tetrahydroretene concentrations decreased. This is the first study reporting the degradation of a variety of resin acids and derived neutrals in an anaerobic sediment.

Effect of H 2O 2 on characteristics and biological treatment of TCF bleached pulp mill effluent

Totally chlorine-free (TCF) bleaching technologies can result in high concentrations of residual hydrogen peroxide in combined mill effluent. This study was undertaken to determine the effect of hydrogen peroxide on effluent characteristics (biochemical oxygen demand (BOD), toxicity), biological sludge characteristics (oxygen uptake rate (OUR), catalase activity) and the efficiency with which laboratory-scale activated sludge reactors treat TCF bleached kraft mill (BKM) effluents. The presence of over 20 mg/L hydrogen peroxide in TCF-BKM effluent was found to decrease the BOD by up to 25%. The complete decomposition of hydrogen peroxide concentrations of up to 1000 mg/L was not found to have an effect upon the effluent toxicity, as measured by Microtox R. Increasing concentrations (5–1000 mg/L influent) of peroxide were continually added to a reactor treating combined TCF-bleached kraft mill effluent. Treatment efficiency, as measured by removal of BOD, chemical oxygen demand (COD) and toxicity, was found to be unaffected by hydrogen peroxide concentrations of up to 1000 mg/L influent. Several methods of gauging reactor acclimatization to hydrogen peroxide were performed throughout the study. Activated sludge mixed liquor samples from the continuous reactor were shocked with varying concentrations of hydrogen peroxide. Oxygen uptake rate of activated sludge samples, especially when unacclimated, was found to decrease dramatically when subjected to shock loads of increasing concentrations of peroxide. Activated sludge which had been acclimated to hydrogen peroxide in the reactor feed was more resistant to H 2O 2 shock loading. Catalase-equivalent induction in activated sludge was also monitored as a means of gauging reactor acclimatization to the presence of hydrogen peroxide. Catalase-equivalent activity was found to increase with increasing H 2O 2 feed concentration, and appeared to reach a maximum level of 1.3–1.5 (min g biomass) −1. It was concluded that activated sludge is able to treat TCF bleached kraft mill effluent which contained H 2O 2, and that the microorganisms present in the sludge were able to adapt to receiving such an effluent.

The effect of pre-hydrolysis of D-stage filtrate on the biotreatability of chlorinated organic compounds in bleached kraft mill effluents

The influence of pre-hydrolysis of D-stage filtrate on the biotreatability of bleached kraft mill effluent was investigated at the bench scale using four continuous aerated “lagoons” operated in parallel. In comparison to non-hydrolyzed effluent, pre-hydrolysis of D-stage filtrate at pH 11 and 60°C for an hour reduced the AOX inlet to the treatment system by 40% and the outlet AOX discharge after biological treatment by 13%. Overall, pre-hydrolysis followed by biological treatment resulted in a 63% AOX removal, which was significantly higher, at the 95% confidence level, than the 58% removal achieved by biological treatment alone. COD and BOD 5 removals for both feeds were 45 and 99%, respectively, and were not significantly affected by the pretreatment. Studies on the pre-hydrolysis effect on known non-biodegradable organochlorine model compounds showed that pre-hydrolysis was effective in improving the biodegradability of a monomeric model, but not the dimeric model compound.

Relationships among effluent constituents in bleached kraft pulp mills

Effluent constituents in a complete ClO 2-substituted bleached Kraft mill were monitored in process lines and sewers for an extended period to determine the transport of these constituents through the mill and its treatment system. The end-of-pipe AOX COD ratio was constant indicating that both COD and AOX at this location are lignin residuals that are not degraded in the treatment system. The ratio was higher for another mill that included Cl 2 in its bleaching sequence. Conductivity at the recovery sewer was a good indicator of black liquor upsets. Significant BOD-COD correlations were found at the pulp mill and evaporator sewers, suggesting that COD from this source is biodegradable. Color and COD correlated well at the end-of-pipe, indicating that color originates from carbon that is not removed during treatment. Color also increased across the pond, suggesting that much of the organic material in the lagoon is not mineralized, but converted into smaller more chromophoric units. No trisubstituted or higher chlorophenols or chlorinated dioxins or furans were found in any of the bleach line filtrates.

Treatment of chlorinated organics in bleached kraft mill effluents by activated sludge process

Combined effluents from a bleached Kraft pulp mill using annual plants were treated in a lab-scale activated sludge (AS) system. The effects of operating solids retention time (SRT) and concentration of additional carbon source on AOX removal were investigated. Higher AOX removals (30%) were observed with long SRTs, 99% of which was pure metabolization. As SRT was decreased AOX removal efficiency also decreased (4%) and principal AOX removal mechanism changed to adsorption onto wasted biomass. The AOX removal efficiency was lower (10%) on a 20% decrease in the supplemental carbon source, with no apparent effect on the removal mechanism.

Nitrogen fixation in an aerated stabilization basin treating bleached kraft mill wastewater

Pulp and paper mill wastewaters normally contain very low concentrations of nitrogen, but many pulp mill aerated stabilization basin (ASB) treatment systems are operated with no supplemental nitrogen, while achieving high biochemical oxygen demand (BOD5) removal. A nutrient mass‐balance study, undertaken across one of the aerated lagoons in such an ASB system, found that a substantial input of nitrogen was occurring within this pond, amounting to approximately 600 kg nitrogen per day. Direct measurement of acetylene reduction (nitrogen fixation), both in the pond and in a laboratory simulation, showed that bacterial nitrogen fixation was responsible for the input of nitrogen. Most of the nitrogen for bacterial growth within the lagoon was supplied by atmospheric nitrogen fixation, and, consequently, nitrogen fixation was critical to overall system effectiveness. It appears that elevated dissolved oxygen concentrations may inhibit fixation. This may be an important constraint on the operation of such ASB systems, especially for the first lagoon, and represents a potential change to current thinking. The implications of bacterial nitrogen fixation, with respect to the effective operation and control of kraft mill ASB systems, are discussed.

A comparison of the potential of primary- and secondary-treated pulp and paper mill effluents to induce mixed function oxygenase (MFO) activity in fish

Primary- and secondary-treated effluents from 13 mills representative of the kraft, chemi-thermomechanical and thermomechanical pulping sectors were tested for their potential to induce mixed function oxygenase (MFO) enzyme activity in rainbow trout ( Oncorhynchus mykiss). Fish were exposed in the laboratory to 1, 5 and 10% (v/v) concentrations of effluents collected at the inlet and the outfall of secondary treatment plants. After 4 days of exposure, hepatic MFO enzyme activities were measured by the ethoxyresorufin-O-deethylase (EROD) assay. Primary-treated effluent from chemi-thermomechanical, thermomechanical and bleached kraft mills showed potential for MFO induction in fish at concentrations of 10% or lower. The MFO-inducing potential of these effluents could not be linked to any specific operating variable such as type of pulping, wood furnish and pulp bleaching or brightening. The ability of the secondary-treated effluents to cause MFO induction was significantly lower or absent at the concentrations tested.

Pyrolysis-GC/AED and pyrolysis-GC/MS analysis of chlorinated structures in aquatic fulvic acids and chlorolignins

A study was undertaken to evaluate whether pyrolysis-gas chromatography/atomic emission detection (PyGC/AED) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) can be used to systematically search for halogenated structures in natural organic matter. Two samples of aquatic fulvic acid (FA) and two samples of high molecular weight organic matter isolated from bleached-kraft mill effluents (BKME) were selected to respectively represent naturally and industrially chlorinated organic matter. Mono- and dichlorophenol were found in the pyrolysates of the naturally chlorinated samples, and methyl esters of 2,4-dichlorobenzoic acid, monochloro-4-methoxybenzoic acid and 3,5-dichloro-4-methoxybenzoic acid were the main compounds detected when a methylating agent, tetramethylammonium hydroxide (TMHA), was added to the samples prior to the pyrolysis. These results strongly indicate the presence of chlorinated 4-hydroxyphenyl structures in the original FA samples. For the BKME samples, on the other hand, the main chlorinated pyrolysis products were guaiacyl- and syringyl-derived compounds.

MFO induction in fish by spent cooking liquors from kraft pulp mills

AbstractWithin bleached kraft mills, the main sources of compounds inducing the mixed function oxygenase (MFO) activities of fish are waste cooking liquor, black liquor, and effluents from the first stages of the bleaching process. We measured the potency for MFO induction in rainbow trout (Oncorhynchus mykiss) of black liquors from pulp mills using kraft pulping and either softwood or hardwood furnish. Concentrations causing induction ranged from 0.0032 to 0.2%(v/v), and below critical thresholds, concentration‐response relationships were linear. Above threshold concentrations, activity declined, and lethality occurred at concentrations greater than 0.1% (v/v) black liquor during 4‐d exposures. Hardwood pulping generated black liquor that was less potent than that from softwood, but much of the difference was due to a higher water content; hardwood black liquor was more dilute as indicated by normalizing results to dissolved organic carbon. Compounds inducing MFO activity may be natural wood extractives associated with wood resins, or compounds created by the digestion of lignin. A high potency of black liquor from alcohol pulping supports the hypothesis of a natural compound because alcohol extraction does not chemically alter lignin to the same extent as kraft pulping; inducing compounds can also be extracted from wood chips with dichloromethane. The high potency of black liquor compared to bleaching or extraction‐stage effluents suggests that control of black liquor losses may be very important in limiting exposure of fish to inducing compounds.

FP 1 Immunomodulation in fish following exposure to bleached kraft mill effluents

FP 1 Immunomodulation in fish following exposure to bleached kraft mill effluents

Treatment system response to transient AOX (adsorbable organic halogen) loadings

If promulgated as proposed, effluent guidelines for the U.S. pulp and paper industry will impose average monthly and maximum daily numerical limits of discharged AOX (adsorbable organic halogen). At this time, it is unclear whether the maximum-day variability factor used to establish the proposed effluent guidelines will provide sufficient margin for mills to achieve compliance during periods of normal but variable operating conditions within the pulping and bleaching processes. Consequently, additional information is needed to relate transient AOX loadings with final AOX discharges. This paper presents a simplistic dynamic model of AOX decay during treatment. The model consists of hydraulic characterization of an activated sludge process and a first-order decay coefficient for AOX removal. Data for model development were acquired by frequent collection of influent and effluent samples at a bleach kraft mill during a bleach plant shutdown and startup sequence.

Inhibition of the sea urchin sperm acrosome reaction by a lignin-derived macromolecule

The major organic components of effluents from commercial pulping processes are lignin-derived macromolecules (LDMs), which have recently been shown to inhibit fertilization and embryonic development in a variety of marine organisms, as well as to exhibit immunostimulating activity in mammalian cells. We conducted studies on the effects of an isolated LDM from bleached kraft mill effluent (BKME), and its sub-components, at the cellular level utilizing the purple sea urchin ( Strongylocentrotus purpuratus) sperm acrosome reaction (AR) as an experimental system. The AR is an event that is induced by the egg's jelly coat and is prerequisite for successful fertilization. Sperm were preincubated with increasing concentrations of isolated LDM or electrophoretically purified LDM sub-components, followed by addition of isolated egg jelly to induce the AR in vitro. These LDM preparations significantly inhibited the AR as assessed by fluorescence (utilizing the rhodamine-conjugated phallicidin) and transmission electron microscopy. Preincubation of sperm with LDM did not have any effect on sperm motility. The level of AR inhibition was comparable to that observed in experiments assessing successful fertilization. The ability of LDM to inhibit jelly induced AR was overcome by the calcium ionophores A23187 and ionomycin. In addition, LDM was shown to inhibit the normal increase in intracellular calcium (Ca ++) associated with induction of the AR. When eggs were preincubated with LDM prior to addition of unexposed sperm, no effect on fertilization was observed, indicating that LDM specifically affects sperm function during fertilization. Fine structural studies, utilizing biotinylated LDM, confirmed LDM's specificity and revealed that its binding was restricted to the plasma membrane domain of the sperm head. The present observations on the inhibition of the AR by LDM is consistent with our hypothesis that this macromolecule inhibits the AR by blocking egg jelly interaction with the sperm surface, thus inhibiting ionic events such as increases in intracellular calcium. Our present approach also demonstrates that echinoderm sperm functions can be used as a model system for the investigation of the mode of action of toxicants at the sub-cellular level.

The effects of oxygen delignification, complete chloride dioxide substitution, and biological treatment on bleached kraft mill effluent quality

The effects of bleaching modifications on the biotreatability of the resulting Adsorbable Organic Halides (AOX) were studied using laboratory-scale bioreactors and mill-scale bleach plant filtrates. Under conventional pulping/bleaching conditions, biological removal of AOX averaged 40 percent. After modification to oxygen delignification and complete ClO2 substitution, the removal efficiency increased to 47 percent. Under the treatment conditions employed, the eight percent increase was found to be statistically significant at a 95 percent confidence level. These results indicate that AOX biotreatability efficiencies following bleaching sequence modifications to oxygen delignification and complete ClO2 substitution remain at least as high as those observed prior to such modifications.

Treatment system response to transient AOX (adsorbable organic halogen) loadings

If promulgated as proposed, effluent guidelines for the U.S. pulp and paper industry will impose average monthly and maximum daily numerical limits of discharged AOX (adsorbable organic halogen). At this time, it is unclear whether the maximum-day variability factor used to establish the proposed effluent guidelines will provide sufficient margin for mills to achieve compliance during periods of normal but variable operating conditions within the pulping and bleaching processes. Consequently, additional information is needed to relate transient AOX loadings with final AOX discharges. This paper presents a simplistic dynamic model of AOX decay during treatment. The model consists of hydraulic characterization of an activated sludge process and a first-order decay coefficient for AOX removal. Data for model development were acquired by frequent collection of influent and effluent samples at a bleach kraft mill during a bleach plant shutdown and startup sequence.

The effects of oxygen delignification, complete chlorine dioxide substitution, and biological treatment on bleached kraft mill effluent quality

The effects of bleaching modifications on the biotreatability of the resulting Adsorbable Organic Halides (AOX) were studied using laboratory-scale bioreactors and mill-scale bleach plant filtrates. Under conventional pulping/bleaching conditions, biological removal of AOX averaged 40 percent. After modification to oxygen delignification and complete C102 substitution, the removal efficiency increased to 47 percent. Under the treatment conditions employed, the eight percent increase was found to be statistically significant at a 95 percent confidence level. These results indicate that AOX biotreatability efficiencies following bleaching sequence modifications to oxygen delignification and complete C102 substitution remain at least as high as those observed prior to such modifications.

Degradation of Chlorophenols by Alcaligenes eutrophus JMP134(pJP4) in Bleached Kraft Mill Effluent

The ability of Alcaligenes eutrophus JMP134(pJP4) to degrade 2,4-dichlorophenoxyacetic acid, 2,4,6-trichlorophenol, and other chlorophenols in a bleached kraft mill effluent was studied. The efficiency of degradation and the survival of strain JMP134 and indigenous microorganisms in short-term batch or long-term semicontinuous incubations performed in microcosms were assessed. After 6 days of incubation, 2,4-dichlorophenoxyacetate (400 ppm) or 2,4,6-trichlorophenol (40 to 100 ppm) were extensively degraded (70 to 100%). In short-term batch incubations, indigenous microorganisms were unable to degrade such of compounds. Degradation of 2,4,6-trichlorophenol by strain JMP134 was significantly lower at 200 to 400 ppm of compound. This strain was also able to degrade 2,4-dichlorophenoxyacetate, 2,4,6-trichlorophenol, 4-chlorophenol, and 2,4,5-trichlorophenol when bleached Kraft mill effluent was amended with mixtures of these compounds. On the other hand, the chlorophenol concentration and the indigenous microorganisms inhibited the growth and survival of the strain in short-term incubations. In long-term (>1-month) incubations, strain JMP134 was unable to maintain a large, stable population, although extensive 2,4,6-trichlorophenol degradation was still observed. The latter is probably due to acclimation of the indigenous microorganisms to degrade 2,4,6-trichlorophenol. Acclimation was observed only in long-term, semicontinuous microcosms.

Structural and functional impairment of the hypothalamo-pituitary-interrenal axis in fish exposed to bleached kraft mill effluent in the St Maurice River, Quebec

The effects of bleached kraft mill effluent (BKME) on blood cortisol levels and the morphology of the pituitary-interrenal axis were investigated in two species of teleost fish, the northern pike, Esox lucius, and the yellow perch, Perca flavescens, sampled upstream and downstream from a pulp and paper mill on the St Maurice River, Quebec. Fish were acutely stressed by a standardized capture and sampling protocol at both sites, and their ability to elevate blood cortisol levels in response to the capture stress was compared. Blood cortisol levels in fish from the upstream site (>100 ng/ml plasma) were higher than the levels in fish from the BKME site, and the pituitary corticotropes and the interrenal steroidogenic cells of the upstream fish were larger and had larger nuclei compared with cells from the downstream fish. The low blood cortisol levels in fish exposed to BKME were correlated to cellular atrophy within the hypothalamo-pituitary-interrenal (HPI) axis. The reduced ability to elevate blood cortisol in response to an acute stress may be an endocrine dysfunction occuring in fish chronically exposed to chemical stressors in their environment

Histopathologic biomarkers in feral freshwater fish populations exposed to different types of contaminant stress

Histopathologic alterations of gill, liver, and spleen were studied in feral fish from three freshwater ecosystems that experience different types of contaminant stress. East Fork Poplar Creek (EFPC), a third-order stream in East Tennessee, receives point source discharges of mixed contaminants from a nuclear weapons facility located near its headwater. The Pigeon River (PR), a high-gradient fifth order stream, is impacted by bleached kraft mill effluent (BKME). Hartwell Reservoir (HR), a US Army Corp of Engineers impoundment of the Savannah River, contains high levels of PCBs in sediment and biota. Brushy Fork Creek (BFC), the Little River (LR), and the Tugaloo River (TR) are relatively free of contaminants, and served as reference sites for the three respective ecosystems of this study. Certain organ and tissue lesions, detected microscopically, were common to fish from both reference and contaminated sites. These included parasites, inflammation, glycogen deficiency, macrophage aggregates (MA), and diffuse fatty change in the liver; parasites and MA in the spleen; and parasites, secondary lamellar fusion, and variable epithelial cell hyperplasia in the gills. Lesions found only in fish from contaminated sites were: (1) cholangiomas in liver of redbreast sunfish ( Lepomis auratus) collected from EFPC; (2) amphophilic and eosinophilic foci of cellular alteration, diffuse biliary preductular and ductular hyperplasia with islands of hyperplastic basophilic hepatocytes, and two metastatic thyroidal carcinomas in spleen of redbreast sunfish from PR; (3) severe lipidosis, vacuolated and basophilic foci in largemouth bass ( Micropterus salmoides) from HR; (4) splenic lymphoid cell depletion and vascular congestion, with necrosis of reticuloendothelial cells in fish collected from EFPC and HR; (5) hyperplasia of mucous and chloride cells, deformed branchial cartilage, severe and diffuse aneurysms of lamellae, and edema at the base of the secondary lamellae were in gill of fish from all three sites. The finding of specific lesions only in fish from contaminated sites suggests a contaminant etiology. Histopathology biomarker lesions identified in this study are similar to those observed in laboratory exposures of fishes to specific pollutants. Further refinement of these biomarker approaches will be discussed in light of multiple stressors and their effects.