Chlorinated fluorenes and alkylfluorenes in bleached kraft pulp and pulp mill discharges

The occurrence and levels of polychlorinated fluorenes (PCFLs), methylfluorenes (C₁-PCFLs) and dimethylfluorenes (C₂-PCFLs) were studied by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) in hardwood and softwood pulp, effluent and biosludge from a bleached kraft mill. Semiquantitative concentrations of these compounds were estimated using selected ion monitoring and a mass spectral resolution of 10,000. The identification of PCFLs and C₁-PCFLs was confirmed by the chlorination mixtures of fluorene and 2-methylfluorene.

Several congeners were found for each compound groups studied and isomer patterns were similar in bleached pulp and biosludge. The approximated sum levels of di- and trichloro isomers of PCFLs, C₁-PCFLs and C₂-PCFLs in the biosludge were about 2, 5 and 4 ng/g dry weight (dw), respectively. The levels of the corresponding compounds in the softwood pulp were 0.5, 0.8 and 0.2 ng/g dw, respectively. Of the studied compounds, only C₁-diCFLs (0.01 ng/g dw) were detected in the hardwood pulp. In the effluent, PCFLs were non-detectable, but traces of C₁-diCFLs (0.5 ng/L) and C₂-pentaCFLs (0.06 ng/L) were found. These were observed mainly as dissolved in the filtrate and not as particle-bound.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans in paper making from a pulp mill in China

An extensive investigation on the input, formation and fate of PCDD/Fs in a pulp mill using reeds as raw materials in China was carried out. The main PCDD/Fs input in the production process came from reeds, which may be contaminated by PCDD/Fs from sodium pentachlorophenate to control snailborne schistosomiasis. High levels of I-TEQ in the products were observed.     

Toxicity to Microtox, micro-algae and duckweed of effluents from the Bai Bang paper company (BAPACO), a Vietnamese bleached kraft pulp and paper mill

Toxicity of the combined effluent as well as effluents from different production units of BAPACO, a Vietnamese bleached kraft integrated pulp and paper mill, was studied using three ecotoxicological tests: Microtox, the micro-alga, Selenastrum capricornutum, and the duckweed, Lemna aequinoctialis. Physico-chemical characteristics of the effluents were also analyzed. Due to unstable operating conditions of the mill, a number of samples taken at different monitoring periods from each effluent were tested, in order to get statistically reliable ranges and averages of toxicity characteristics. For the mill combined effluent, it was found that the micro-algae were the most sensitive followed by Microtox bacteria, while duckweed was not sensitive. Microtox tests showed that the bleaching filtrate from the chlorination stage (C-stage) was the most toxic among all effluents in the mill. The combined effluent from the bleaching plant contributed the largest TEF (Toxicity Emission Factor) to the toxicity balance of the whole BAPACO combined effluent. A less-than-additive mode of toxicity was obtained. In spite of high pollution loads, e.g. BOD, COD, SS, to the Red River, the toxicity of the effluent was considered to be low. However, during periods of low river water sublethal toxic effects on the biota may be expected.     

Assessing the biological status of fish in a river receiving pulp and paper mill effluents

This study compared the use of sentinel species- and community-based field approaches for assessing the biological status of fish living in a river receiving pulp and paper mill effluents. Three approaches were compared. Two approaches used sentinel species. One of these involved an internal/external examination of the fish that leads to the calculation of a fish health assessment index (HAI) and the other involved biochemical measurements of hepatic mixed function oxidase (MFO) activity and plasma steroid levels. The third approach characterized the fish community structure according to an index of biotic integrity (IBI). The comparison focused on how the methods respond to the hypothesis that recent process modifications/effluent treatment changes, resulting in demonstrable improvements in effluent quality, have beneficial effects on fish. Neither of the approaches using sentinel fish indicated clear mill-related influences either before or after the process modifications/effluent treatment changes. There was no evidence of depressed plasma steroids and increased MFO activity in fish frequently associated with mill effluent exposure in previous studies. While the HAI was higher at stations downstream from two mills, this could not be linked to effluent exposure alone. In contrast, the study of community structure showed a substantial improvement in fish assemblages at all the mill sites.     

Determining algal-available phosphorus in pulp and paper mill effluents: algal assays vs routine phosphorus analyses

We determined the potentially algal-available P (P(aa)) in pulp and paper mill effluents by two bioassay techniques (a dual-culture assay and a batch approach) and compared it with chemically analysed P (total P, total dissolved P, reactive P, dissolved reactive P and dissolved hydrolysable P). The mean P(aa) given by the dual-culture assay was within a 40% range of that given by the batch approach. The P(aa) obtained by both bioassays differed from total P. Dissolved reactive P appeared to be the most readily available chemical P fraction, but other P fractions also contributed to P(aa). The analysis of reactive P, which involves direct staining of an unfiltered sample, best approximated the P(aa) given by the dual-culture assay (relative error 9%). The results suggest that assessment of eutrophying effluent P can be improved by analysing simple chemical P fractions in wastewater. The fractions to be analysed, however, may be site specific.     

Betulinol and wood sterols in sediments contaminated by pulp and paper mill effluents: dissolution and spatial distribution

The goal was to determine dissolution potency of betulinol and wood sterols (WSs) from pulp and paper mill-contaminated sediments and the current stratification for assessment the load due to potential erosion in the river-like watercourse. Both compounds are wood extractives, which may be toxic to benthos and fish. This research continues a study in which other wood extractives, resin acids and their derivative, retene, were analysed. Sediments were collected from 1, 3.5, 12, 15, and 33 km downstream from the pulp and paper mills, and from 2 upstream reference sites. The dissolution potency into sediment–water elutriates (1?+?4?v/v) was studied by two agitation times and temperatures. The vertical amounts of extractives were determined from the uppermost 20 cm of sediment. The amounts of extractives potentially released were estimated from the sediment layers 0–2 and 2–5 cm by using spatial interpolation. According to the interpolation, the total amount of betulinol and β-sitosterol was calculated as kg/ha in the whole sediment area. Significant concentrations of betulinol (1,666 μg/g, dw) and WSs (2,886 μg/g, dw) were measured from the sediments. According spatial interpolation, the highest calculated amount of betulinol (4,726 kg/ha) and that of the most abundant WS, β-sitosterol (3,571 kg/ha), were in the lake where the effluents were discharged. In the dissolution experiment, the highest concentration of betulinol in sediment (0–10 cm) and elutriate was 412 μg/g (dw) and 165 μg/l, respectively. For WSs, concentrations were 768 μg/g (dw) in sediment and 273 μg/l in elutriate. In a worst-case scenario, betulinol may be desorbed to water in concentrations which are hazardous to aquatic animals. Instead WSs are not a risk in this study area. The amount of desorption varied depending on the concentration of contaminants in sediment, the nature of disturbance, and the sediment organic carbon content.     

Fish community responses to pulp and paper mill effluents at the southern Lake Saimaa, Finland.

The fish community in sublittoral and profundal waters, at stony shores, and densities of vendace larvae were studied in the southern Lake Saimaa, Finland. The objective was to investigate the possible recovery of fish populations after modernizations at the pulp and paper mills discharging into the lake. Sublittoral and profundal waters were studied by gill net trial fishings, stony shores by electrofishing, and vendace larvae by beach seine. The research area was divided in a polluted (0.5-4.0% effluent), an intermediate (0.1-0.5%) and a 'clean' reference area. The fish community in sublittoral and profundal waters in the lake was dominated (> 60%) by perch and roach. Relative abundance of fish was highest in the polluted area, and lowest in the reference area. The number of species caught was similar among areas. The abundance of bleak and ruffe was highest in the polluted area, while the abundance of vendace and whitefish was highest in the intermediate and reference area. The fish fauna of stony shores in the lake was dominated by bullhead, stone loach and minnow, densities were lowest at polluted shores and highest in the intermediate area. Minnow, apparently a more sensitive species to pulp mill effluents, were not caught at the most polluted shores. The catch of vendace larvae was similar among areas, larvae were also caught in the vicinity of the mills. Compared with before the modernization at the mills, the relative abundance of perch in the polluted area was increased, ruffe decreased, while populations of whitefish and vendace showed signs of recovery. These changes may be explained by the reduced nutrient load and toxicicity of pulp mill effluents. At present, the fish community in the polluted area can be considered typical for a moderate eutrophication.     

Effects of solar radiation on the fluorescence properties and molecular weight of fulvic acids from pulp mill effluents

The pulp and paper industry generates large volume of wastewater that adversely affects water resources. Lignin derived macromolecular compounds, similar to natural humic substances, are the main waste products in the pulp mill effluents. The UV-Vis and fluorescence spectroscopies were used to assess the effect of solar exposition on fulvic acids from a kraft pulp mill effluent. Solar irradiation of the solutions of these fulvic acids caused solution acidification and decay both in the UV-Vis absorbance and in the fluorescence. This decay was not the same for the whole spectra but pointed to the selective photodegradation of lignin typical structures. Furthermore, by sequential ultrafiltration it was found that during irradiation, the high-molecular weight fractions were destroyed and low-molecular-weight constituents, potentially more able to penetrate the cell membranes of living organisms were formed. Photodegradation of macromolecular organic matter from a kraft pulp mill effluent may be a key process occurring in natural waters that modifies the physicochemical properties of such effluents.     

Identification and level estimation of chlorinated neutral aromatic sulfur compounds and their alkylated derivatives in pulp mill effluents and sediments

Seven effluent samples from a modern pulp mill, in which chlorine and chlorine dioxide bleaching is used, and five sediment samples from the recipient watercourse were investigated for polychlorinated dibenzothiophenes (PCDBTs), polychlorinated thianthrenes (PCTAs), polychlorinated diphenylsulfides (PCDPSs) and for alkylated derivatives of these. Mainly di-, tri-, tetra- and pentachlorinated congeners were studied. Particles and filtrates from the effluents were analyzed separately. The concentration levels of the nonalkylated compounds were found to be higher in the filtrates than in the particles. Trichlorinated dibenzothiophenes and thianthrenes were found as the major congeners. Pentachlorinated derivatives were not found. Alkylated di- and trichlorodibenzothiophenes were detected in some samples, while alkylated chlorinated thianthrenes and diphenylsulfides were nondetectable. The estimated concentration levels of the compounds detected were in the range of 40–2700 pg/L in the pulp mill effluents and in the range of 2–40 pg/g dry weight in the sediments. Mixtures of methylated di- and trichlorodibenzothiophenes used as references in analyses were prepared from methylchlorobiphenyls. Some new pure model compounds were obtained by HPLC fractionation of the chlorination mixture of dibenzothiophene. Structures of these were determined by ¹H NMR.     

Effects of bleached kraft mill effluents on the swimming activity of Monoporeia affinis (crustacea, amphipoda) lindström

The crustacean Monoporeia affinis Lindström was exposed to two different concentrations of bleached kraft mill effluent (BKME) containing, originally, 8.3 mg/g organic chlorine determined as adsorbable organic halogen (AOX). The swimming activity of the animals was recorded by pairs of infra-red sensitive photocells attached to 5.6 1 aquaria having a seawater inflow rate of 12 ml/min. The test sequence included a control phase, an exposure phase and a recovery phase. During the exposure phase the total swimming activity decreased in three of the four test aquaria containing effluent, indicating that the animals had retreated into the sediment. Total activity increased during the recovery phase and, in the case of the lower organic chlorine concentration, activity almost achieved the original control-phase level. Statistical differences in swimming activity changes during experiment were evaluated using ANOVA. Experimental methods are explained in detail.     

UASB performance for bleached and unbleached kraft pulp synthetic wastewater treatment

This paper presents the performance of two bench scale Upflow Anaerobic Sludge Blanket reactors (UASB) used for the treatment of synthetic substrates that simulate bleached and unbleached cellulose pulp plant wastewaters. The control reactor was fed with diluted black liquor and the treatment reactor with the same substrate plus a mixture of chlorinated organics. The total concentration of the chlorinated compounds was gradually increased from 2.5 mg l-1 to 15.0 mg l-1. The average COD removal efficiency during the last phase of the experiment was 81% in the control reactor and 76% in the treatment reactor. These results indicate the capability of UASB reactors to treat this kind of wastewater and the low impact of the chlorinated organics on COD removal efficiency. The minimum overall chlorinated organics removal efficiency was 71% and the maximum was 99.7%. The experiment indicates that under the conditions used in this research the presence of chlorinated organics does not negatively impact the treatment process.     

A laboratory exposure procedure for screening pulp and paper mill effluents for the potential of causing increased mixed function oxidase activity in fish

To better understand the relationships between pulp manufacturing processes and mixed function oxidase (MFO) enzyme induction in fish, a practical and standardized exposure procedure is required. This study was undertaken to develop a laboratory-based exposure procedure to quantify the relative MFO induction potencies of different types of pulp and paper mill effluents. One major consideration in developing the procedure was to ensure that the protocol was practical so that tests could be performed in a short time, with small volumes of effluents and using simple experimental conditions. A series of concentration-response and time-course experiments were conducted to find the minimum time and effluent concentration which could distinguish the ability of different effluents to cause significant MFO induction in rainbow trout in the laboratory. Experiments were also conducted to determine the effects of biotic and abiotic factors such as loading density, fish size and feeding regime. This study showed that the exposure of rainbow trout in the laboratory to 10% concentration of secondary-treated effluent for 96 h caused significant increases in hepatic MFO activity. The magnitude of MFO induction was comparable to other field and laboratory observations. While fish size, loading density and feeding regime were found to affect the test results, consistent responses within a laboratory using this protocol are possible, provided that these factors are standardized. Therefore, the short-term exposure approach described in this paper could be a relevant tool for assessing the ability of different types of pulp and paper mill effluents to cause MFO induction in fish.     

Removal of AOX, total nitrogen and chlorinated lignin from bleached Kraft mill effluents by UV oxidation in the presence of hydrogen peroxide utilizing TiO2 as photocatalyst

Background, aim, and scope  The pulp and paper industry is the sixth largest polluter discharging a variety of gaseous, liquid, and solid wastes into the environment. Effluents from bleached Kraft mill effluents (BKME) are polluting waters to a great extent These effluents cause considerable damage to the receiving waters if discharged untreated since they have high levels of biological oxygen demand (BOD), chemical oxygen demand (COD), chlorinated compounds (measured as AOX), suspended solids (mainly fibers), fatty acids, tannins, resin acids, lignin and its derivatives, sulfur and sulfur compounds, etc. This study aimed to remove adsorbed organic halogen (AOX), total nitrogen, and lignin-degrading products in the wastewater (4,500 m³/h) from the paper mill in the pulp and paper industry, which is discharged to sea from a plant located in western Turkey. Materials and methods  The photocatalytic degradation of AOX, total nitrogen, and chlorinated lignin in BKME have been investigated in different parameters, such as time, H₂O₂ and TiO₂ concentration. In addition, for investigating the effect of chlorine on the removal of lignin, pure lignin solution was prepared in equal amounts to chlorinated lignin degradation products found in BKME. The same experiments were conducted for this solution. Experiments were carried out in photocatalytic reactor made of Pyrex glass. The mercury lamp was used as a radiation source. All irradiation was carried out under constant stirring. The existence of dissolved O₂ is an important factor which increases the photocatalytic degradation. Hence, we used an air pump for the aeration of the wastewater solutions. The temperature of the wastewater was controlled and adjusted to 25°C by thermostat pump in conjunction with a cooler. At the end of all experiments, AOX, total nitrogen and lignin concentrations were analyzed according to standard methods. All experiments were performed in duplicate and average values were used. Results and discussion  When the effect of H₂O₂ and time were investigated, it was observed that the AOX concentration increased from 3.0 to 11.0 mg/L by only UV. However, when H₂O₂ was added, AOX concentration decreased from approximately 3.0 to 0.0 mg/L. The optimal conditions for the removal of AOX appear to be an initial H₂O₂ concentration of 20.0 mL/L and reaction time of 50 min. In addition, at the same experiment conditions, it was seen that the total nitrogen concentration decreased from 23.0 to 15.0 mg/L by only UV and by increasing H₂O₂ concentration, the concentration of 20.0 mL/L H₂O₂ appears to be optimal (9.0 mg/L). The AOX, total nitrogen and lignin degradation products and pure lignin go through a minimum when the concentration of H₂O₂ and TiO₂ increases at constant pH and UV intensity. The kinetics for the degradation of AOX, total nitrogen and lignin degradation products followed a pseudo-first order law with respect to the products, and the degradation rates (min⁻¹) for the UV/TiO₂/H₂O₂ system were higher than that of the corresponding values for the UV/H₂O₂ system. Conclusions  The AOX, total nitrogen and lignin concentration go through a minimum when the concentration of H₂O₂ and TiO₂ increases at constant pH and UV intensity. It was found that the UV/TiO₂/H₂O₂ system has proved capable of the degradation of total nitrogen as well as chlorinated and degraded lignin in BKME. Recommendations and perspectives  The photocatalytic process can be considered a suitable alternative for the remove of some compounds from the BKME. Nevertheless, further studies should be carried out to confirm the practical feasibility of BKME. Another result obtained from the study is that pre-purification carried out with UV/TiO₂/H₂O₂ photocatalytic process may constitute an important step for further purification processes such as adsorption, membrane processes, etc.     

Treatment of bleach pulp mill effluent by MF-MBR

The types of treatment most commonly used by pulp mills are biological treatments in combination with sedimentation or coagulation/flocculation as pretreatment. The main issues faced by these types of treatment are low efficiency in the removal of organic matter and the loss of aggregate value for the recovered fiber. Therefore, this study aims to evaluate the use of microfiltration (MF) combined with a membrane bioreactor (MBR) for the treatment of bleach pulp mill effluents. The results showed that the use of the MF-MBR system was an excellent alternative for the treatment of bleach pulp mill effluents with an average COD removal of 95%. The microfiltration allowed the recovery of fibers, which can be returned to the production process without losing economic value, and produced a better quality effluent for further treatment in the MBR. The MBR presented high efficiency removal of organic matter.     

Fate of pulp mill effluent compounds in a finnish watercourse

Chloroorganic chemicals emitted from the pulp and paper mill at nekoski in central Finland were monitored for several years. Concentration time series are used for evaluating the environmental fate and the applicability and validity of an exposure models. Fitted elimination rates of 3,4,5-Tri-, 4,5,6-Tri-, Tetrachloroguaiacol and 2,4,6-Trichlorophenol are approx. 0.22 d^-1, or rather the half-lives are approx. 3 days. The elimination is most likely by biodegradation and transport-controlled. For 2,3,6-trichloro-p-cymene, fate simulations indicate significant volatilization and sedimentation. Good agreement is achieved with a one-dimensional steady-state box model, except for concentrations in fish. For a reliable assessment of environmental damage, laboratory experiments, monitoring and simulations need to be in tune.     

Photocatalytic detoxification of cyanide and metal cyano-species from precious-metal mill effluents

Photochemically-induced detoxification of various cyanide species from a selected precious-metal mills tailings was investigated in detail. The studies were conducted in the presence or absence of a titanium (IV) oxide semiconductor photocatalyst utilizing simulated sunlight as the irradiation source. It was established that the cyanide ion (both free and complexed) was photocatalytically oxidized to nitrate via cyanate and nitrite. In addition iron, copper, zinc, mercury and arsenic were stabilized as precipitates. The results obtained may have ramifications for the possible use of solar energy for the efficient treatment of large quantities of precious-metal mill-tailing wastes that contain various cyano-species.     

Isolation of MFO inducers from tissues of white suckers caged in bleached kraft mill effluent

White sucker (Catostomus commersoni) caged for 3 days in a bleached kraft mill effluent (BKME) stream had elevated mixed function oxygenase (MFO) activities 15-90 fold those of fish caged in a reference stream. Liver composites of male and female fish were ground and extracted with dichloromethane (DCM), methanol or 50% DCM/methanol, and tested for MFO activity in rat hepatoma cells (H4IIE). There was no difference in the potency of H4IIE EROD induction among the three solvents, so DCM extracts were split into 31 fractions using reverse phase high pressure liquid chromatography (HPLC). H4IIE MFO activity was elevated in several fractions, with three early peaks and several later peaks of induction, indicating several classes or compounds causing MFO induction were present in the fish livers. Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and chlorinated diphenylethers (CDPEs) were detected in several late-eluting fractions, but concentrations were not high enough for these compounds to be solely responsible for the observed induction. Induction by liver extracts decreased as cell exposure times increased (24, 48 or 72 h), suggesting that some inducers were more easily metabolized and eliminated from the H4IIE cells. In contrast, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2378-TCDD) had similar potency over 24, 48 and 72 h, as it was relatively resistant to metabolism.     

Effects of pulp mill chlorate on Baltic Sea algae

The long-term effects of pulp mill chlorate on different algal species of the Baltic Sea were studied in land-based model ecosystems simulating the littoral zone. Brown algae (Phaeophyta) exhibited an extraordinarily high sensitivity to chlorate and pulp mill effluents containing chlorate. All brown algal species ceased growth or showed major signs of toxicity at all concentrations tested, down to microgram per litre levels. EC50 levels for growth of Fucus vesiculosus were about 80-100 microg ClO3- litre(-1). Blue-green algae (Cyanophyta) were not deleteriously affected nor were green algae (Chlorophyta). The perennial and annual species of red algae (Rhodophyta) were also unaffected by the effluents. Diatoms did not show any sensitivity and phytoplankton (fresh- and brackish water) were particularly insensitive. A phanerogam, Zostera marina was also unaffected by the treatments.     

Advanced oxidation of a pulp mill bleaching wastewater.

The degradation, by several advanced oxidation reactions, of a pulp mill ECF bleaching effluent, was studied. The initial biodegradability of the organic matter present in the effluent, estimated as the BOD5/COD, was low (0.3). When the effluent was submitted to ozonation and to five different advanced oxidation systems (O3/UV, O3/UV/ZnO, O3/UV/TiO2, O2/UV/ZnO, O2/UV/TiO2), the biodegradability increase significantly. After five minutes of reaction, the O3/UV system appears as the most efficient in to transform the organic matter to more biodegradable forms. A similar effect was observed when the effluent was submitted to an activated sludge treatment. The COD, TOC and toxicity reduction correlated well with the biodegradability enhancement after AOPs treatments.     

Bleached kraft pulp mill discharged organic matter in recipient lake sediment

Environmental properties of organic matter contained halogen and sulfur were studied in sediments of bleached kraft pulp mill effluent (BKME) recipient lakes and 2 m³ outdoor enclosures (mesocosms). The BKME contributed to 1% (v/v) of the total water flow in the lake downstream of the pulp mill where the sediments contained 1.7 to 4 mg of tetrahydrofuran extractable organic halogen (EOX-Cl) and 0.6 to 0.8 mg of tetrahydrofuran extractable organic sulfur (EOS-S) g⁻¹ of organic matter. Upstream sediment contained 0.03 mg of EOXCl and 0.7 mg of EOS-S g⁻¹ of organic matter. EOX was a better indicator for the influence of BKME in the recipient sediment than EOS. The polarity of BKME contained EOX corresponded to log K^ow of < 1, and that of the downstream sediment contained EOX to > 4.5. HP-SEC analysis of the molecular weight distribution (MWD) of the EOX showed a peak between 300 to 600 g mol⁻¹ for the BKME and between 1000 to 2000 g mol⁻¹ for the downstream sediment. The MWD of the BKME contained EOS peaked at 300 to 1000 g mol⁻¹, and that of the downstream sediment contained EOS at 1000 to 5000 g mol⁻¹. These results indicate that BKME contained organic halogen and sulfur undergo major structural transformations when incorporated into sediment. The biota-to-sediment accumulation factor (BSAF) of EOX from sediments formed downstream of the mill and in the mesocosms to the lipids ofLumbriculus variegatus was 0.4 to 0.7. This is of a similar order of magnitude to the BSAF reported for 2,3,7,8-tetrachlorodibenzop-dioxin and 2,3,7,8-tetrachlorodibenzofuran.