Bleached Kraft Pulp Mill Research Articles

Kinetics of organochlorine removal from bleached kraft pulp mill effluent during biological treatment

AbstractBatch biodegradation kinetic studies were conducted with various bleached kraft pulp mill effluents containing organically bound chlorine measured as adsorbable organic halogen (AOX) (6.0 ‐ 35 mg Cl/L). Biomass, generated in both a continuous bench scale reactor and a mill scale activated sludge system, at various concentrations (0.4 ‐ 3.1 g VSS/L) was added to various effluents (about 70% ClO2 substitution).AOX removal kinetics were best described by a simple recalcitrant first order model: ‐ dS/dt = ks,1X(S‐S∞), where S and S∞ are AOX concentrations (mg Cl/L) at time t and t∞, respectively, ks,1 is the AOX removal rate constant (L/g VSS.h) and X is the biomass concentration (g VSS/L). The model indicated a constant non‐biodegradable fraction of AOX (0.4 mg of AOX per mg of influent AOX) and was able to predict the effect of dilution on AOX removal with a single value of ks,1 (0.13 L /g VSS.h). The degradation constants (0.16 L /g VSS.h) in the absence of effluent from the neutral sewer (i.e. for a mixture of acidic and alkaline effluent only) were significantly higher than those for whole mill effluent.

Experiences of wastewater treatment in Chilean forest industry

The present situation of water treatment facilities in the forest industry of Chile is briefly described. Some data of the Chilean pulp mill production and the present level of water pollution are shown. This paper is the result of five years of applied research conducted to study and evaluate liquid effluent treatment from pulp, paper and board mills. We describe laboratory results corresponding to three industrial mills that we have studied. The first case presented in this paper corresponds to a bleached Kraft pulp mill with a fiber line consisting in a MCC digester, a delignification unit and four steps in bleaching. In this mill the effluents are treated in an extended lagoon and the suspended solids are settled in a primary treatment. Lab scale lagoons were installed to developed start up strategies and to determine optimal operational efficiencies. The second case that we present is a paper mill, with primary treatment in an air flotation unit used for separating suspended solids. A technical economical analysis was necessary to burn solid sludge in order to improve energy balance. Finally, the third case we have studied corresponds to a hardboard mill effluent. In this case, high COD, mainly as colloidal solids, characterize this effluent. Laboratory experiences were made using a system of two sequential aerated lagoons.

Modifications of the reproductive period in mummichog (<I>Fundulus heteroclitus</I>) living downstream from a bleached kraft pulp mill in the Miramichi Estuary, New Brunswick, Canada

Modifications of the reproductive period in mummichog (<I>Fundulus heteroclitus</I>) living downstream from a bleached kraft pulp mill in the Miramichi Estuary, New Brunswick, Canada

Non-process elements in a bleached kraft pulp mill with a high degree of system closure - state of the art

Non-process elements in a bleached kraft pulp mill with a high degree of system closure - state of the art

The influence of anoxic conditioning of sludge on enhanced AOX (adsorbable organic halogen) removal in aerobic biological treatment systems

The increasingly stringent limits on the discharge of adsorbable organic halogen (AOX) from bleached kraft pulp mills have resulted in a need to optimize the performance of biological wastewater treatment systems with respect to the removal of these compounds. To investigate whether anoxic conditioning of sludge can enhance AOX removal in activated sludge systems, a series of batch experiments was conducted where reactors were seeded with various proportions of activated and anoxic-conditioned sludges. AOX removal was found to be significantly enhanced through the addition of anoxic-conditioned sludge to activated sludge, resulting in overall AOX removal of up to 75%. The extent of enhancement ranged from 3 to approximately 10% as the conditioning time was increased from 5 to 20 days. The benefit then declined as the conditioning times increased further beyond 20 days and up to 30 days. The effect of conditioning time on COD removal followed a similar trend as for AOX removal. An optimal AOX removal was achieved when the proportion of conditioned sludge within the biomass was 30%. A good correlation between the enhanced AOX removal and increasing levels of facultative bacteria developed in the conditioned sludge was observed. The addition of sulphate into the sludge during conditioning further increased the enhancement of AOX removal when compared to sludges conditioned under nitrogen.

Environmental impacts of pulp and paper wastewater: Evidence for a reduction in environmental effects at North American pulp mills since 1992

In the early 1990s, a variety of responses were reported in fish populations living downstream of bleached kraft pulp mills. This included delayed sexual maturity, smaller gonads, changes in fecundity, and a depression in secondary sexual characteristics. The changes in fish reproductive development were also associated with alterations in the endocrine mechanisms controlling the production of the sex steroid hormones. The early studies were conducted predominantly at large bleached kraft pulp mills with primitive pulping processes and little effluent treatment. Subsequent studies documented several of the changes at some sites with effluent treatment and without chlorine use, and the dominant reproductive changes (delayed maturity, reduced egg production, changes in secondary sexual characteristics) were replicated in laboratory fish exposed to secondary-treated effluent. Studies have continued to follow the responses of wild fish as these mills underwent process modifications and installed secondary treatment. Improvements in the performance of wild fish have been recorded at five North American sites after the mills modernized their waste treatment and pulping processes. However, the improvements are not complete and are not universal and the process changes resulting in the improvement in environmental conditions have not been defined and their identification remains a priority. Reductions in gonad size and depressions of sex hormones are still seen at one mill with 100% chlorine dioxide substitution and secondary treatment.

Growth responses of periphyton and chironomids exposed to biologically treated bleached kraft pulp mill effluent

Experiments were conducted in artificial streams to determine the effects of increasing concentrations of biologically treated bleached kraft pulp mill effluent (BKPME) on periphyton and chironomid growth in the Thompson River, British Columbia. Periphyton growth, as determined by increases in chlorophyll a, was significantly stimulated at all effluent concentrations tested (0.25%, 0.5%, 1.0%, 5.0% and, 10.0%). Chironomid growth (individual weight) was also significantly stimulated at low effluent concentrations (≤1.0%). At higher concentrations (5.0% and 10.0%), chironomid growth was inhibited relative to the 1.0% treatment streams. Increases in growth were attributed to the effects of nutrient and organic enrichment from BKPME. The effluent contained high concentrations of phosphorus and appears to be an important source of carbon for benthic insects grazing on the biofilm. In high concentration effluent streams, chironomid growth decreased despite low levels of typical pulp mill contaminants. This suggests that other compounds in the effluent, such as wood extractives, may be inhibiting chironomid growth. These results support findings of field monitoring studies conducted in the Thompson River where changes in periphyton and chironomid abundance occurred downstream of the bleached kraft pulp mill.

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 in the effluent of the pulp and paper industry

Nitrogen concentrations of effluent before and after treatment plant in two mills have been measured during five days time in a bleached kraft pulp mill and in a newsprint mill. In effluents before treatment the concentration of inorganic nitrogen was low but in the effluent of kraft pulping process, the main part is inorganic nitrogen. In effluent after treatment the concentration of inorganic nitrogen is low. After activated sludge treatment plant the concentration of dissolved organic nitrogen is about 0.6 mg/l and nitrogen in suspended solids determines fluctuation of nitrogen content in treated effluent. There is no need for biological nitrogen removal processes if the addition of nitrogen in the treatment is correct.

Experiences of wastewater treatment in chilean forest industry

The present situation of water treatment facilities in the forest industry of Chile is briefly described. Some data of the Chilean pulp mill production and the present level of water pollution are shown. This paper is the result of five years of applied research conducted to study and evaluate liquid effluent treatment from pulp, paper and board mills. We describe laboratory results corresponding to three industrial mills that we have studied. The first case presented in this paper corresponds to a bleached Kraft pulp mill with a fiber line consisting in a MCC digester, a delignification- unit and four steps in bleaching. In this mill the effluents are treated in an extended lagoon and the suspended solids are settled in a primary treatment. Lab scale lagoons were installed to developed start up strategies and to determine optimal operational efficiencies. The second case that we present is a paper mill, with primary treatment in an air flotation unit used for separating suspended solids. A technical economical analysis was necessary to bum solid sludge in order to improve energy balance. Finally, the third case we have studied corresponds to a hardboard mill effluent. In this case, high COD, mainly as colloidal solids, characterize this effluent. Laboratory experiences were made using a system of two sequential aerated lagoons.

Nutrient limitation and herbivory: processes influenced by bleached kraft pulp mill effluent

Nutrient limitation and herbivory: processes influenced by bleached kraft pulp mill effluent

環境 ＩＶ 紙パルプ産業と地球環境序論

Japanese Pulp and Paper Industries had overcome the pollution problems mainly of air and water pollution which struck the industries on '70s.For the pollution control, Japanese pulp and paper industries invested not only to the end pipe treatment such as waste water treatment and stack gas desulfurization but also to the reductions of pollutant by the improvements of the production process and others. Investments for the pollution control for three years from 1974 to 1976, while the largest investment were took place for the pollution control, was over 140 billion Yen.Along with above investments, each mill placed an officially qualified “Manager in Charge of Pollution Control”, Who organizes the pollution control activities in the mill.In 1990, dioxins from the waste water of the bleaching plant of the pulp mill became a social concern, and Japanese pulp and paper industries took measures such as installation of oxygen dilignification plant, stabilization of Kappa Number and improvement of washing process to reduce the consumption of chlorine. By these measures, all the bleached kraft pulp mill cleared maximum discharge of 1.5 kg/ton of pulp, the voluntary reduction target of AOX discharge set by Japan Paper Association, at the end of 1993.Coming 21st Century is said to be a century of the Global Environment. Problems concerning the Global Environment such as global warming. differing from the pollution problems, is not caused by the specific substances emitted by specific industrial activities, but is caused by the various activity of human being including the normal living activity, and no simple measure is available.How we, pulp and paper industries should deal with the Global Environment Problems and maintain the Sustainable Development at the same time is discussed.

Bleached kraft pulp mill sourced organic chemicals in sediments from a New Zealand River. Part II: Tarawera river

The concentrations of resin acids, chlorophenolic compounds and resin acid derived neutral compounds (fichtelite, dehydroabietin, tetrahydroretene and retene) were measured in river sediments above and below the effluent discharges of two New Zealand pulp and paper mills. The two mills, a sulphonated chemithermomechanical pulp (CTMP) and tissue mill, and an integrated kraft and mechanical pulp and paper mill, discharge secondary treated effluent into the Tarawera River in New Zealand. No significant concentrations of pulp and paper mill sourced organic compounds were found at background sites. Below the CTMP mill slight increases in the concentrations of the resin acids and resin acid derived neutral compounds were measured. Elevated concentrations of all three compound classes were observed downstream of the second pulp and paper mill. Total concentrations of chlorophenolic compounds and resin acids in the river sediments from below the second mill effluent discharge reached to 17.0 ng g −1 and 23.1 μg g −1 dry weight respectively. Still higher concentrations of chlorophenolic compounds and resin acids, 58.7 ng g −1 and 94.5 μg g −1 respectively, were present in sediments from a downstream estuarine lagoon which was previously part of the river system. The organic carbon content in sediments was a principle constituent governing the concentrations of pulp and paper mill derived compounds in the New Zealand receiving water systems.

The effect of enzyme treatment on untreated d-stage effluent: Short-term fish early life-stage toxicity test

Short-term early-life-stage toxicity experiments were conducted using zebra fish (Brachydanio rerio) under semistatic conditions. The test parameters studied were percent hatching success, median time from fertilization to hatching, median survival of embryos and larvae, frequency of abnormal larvae, as well as larval growth. Test organisms were exposed to a sample of raw spent bleach liquor from the D-stage of a softwood bleached-kraft pulp mill and the sample after treatment with a peroxidase enzyme, which resulted in a 50% decrease in residual phenolic components (0.123 vs. 0.061mg/L). In the untreated D-stage sample, the median survival of embryos and larvae was calculated to be 151 ml/L; the lowest-observed-effect concentration was 50 ml/L, and the no-observed-effect concentration was 25ml/L. No dose response could be established for fish exposed to peroxidase-treated D-stage liquor; the treated effluent was only minimally toxic in this short-term test.

Design of a representative and cost-effective sampling programs for industrial wastewater with examples from bleached kraft pulp and paper mills

The diagram constructed for selection of sampling methods indicates that, for a systematic error, E ≤ 13%, grab sampling (GS) may be used to characterize effluents with variation coefficient of flow ≤ 120% and of contaminant concentrations ≤ 10%. For the whole studied range of variation coefficient of contaminant concentrations (2–82%), time-proportional compositing (TC) method may be applied with E ≤ 10% for effluents characterized by variation coefficients in flow < 90%. The more complicated flow-proportional compositing (FC) method is required only for effluents with larger variation coefficients or to produce more precise results. The diagram constructed for selection of sampling frequencies indicates that sequential sampling at intervals of approximately 60 min may be applied with E ≤ 10% for effluents characterized by variation coefficients ≤ 30%. Practical application of the diagrams, constructed using normal series, was checked against monitoring data from two pulp and paper mills in Vietnam. The two diagrams provided results on sampling methods and frequencies in good agreement with those obtained from actual monitoring data with percentages of agreement cases of 80 and 75%, respectively. The approach was applied in design of a monitoring program at the Bai Bang integrated pulp and paper mill in Vietnam.

Patterns, trends, and toxicological significance of chlorinated hydrocarbon and mercury contaminants in bald eagle eggs from the pacific coast of Canada, 1990–1994

Bald eagle (Haliaeetus leucocephalus) eggs were collected during incubation, 1990-1992, from 16 nests near three bleached-kraft pulp mills, from six nests in the Fraser River estuary and from seven nests at a reference site on the Pacific coast of Canada. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were present in all eggs in a qualitatively similar pattern among sites. Mean concentrations of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) were significantly higher in eggs collected from near three kraft pulp mill sites in the Strait of Georgia (44, 45, 84 ng/kg) than from the reference area in Johnstone Strait (15 ng/kg). There were few differences among sites in mean organochlorine pesticide levels, indicating the diffuse distribution of those chemicals and the domination of atmospheric inputs. Mean concentrations of total polychlorinated biphenyls (PCBs) were highest in eggs from the Strait of Georgia (4.86 mg/kg) and the PCB congener pattern was significantly different between that area and both the lower Fraser valley and Johnstone Strait. Mean mercury concentrations, which were mainly methyl-mercury, were significantly higher in eggs collected from the lower Fraser Valley (0.258 mg/kg) and Johnstone Strait (0.294 mg/kg) compared to the Strait of Georgia (0.188 mg/kg). Individual and regional variation in concentrations of organochlorine pesticides, PCBs and mercury in eagle eggs were thought to be influenced mainly by dietary differences. Toxicologically, in 1990, mean TCDD-toxic equivalents (TEQs) in bald eagle eggs were about two-fold greater than a lowest-observed-effect level, suggested elsewhere for this species, of 210 ng/kg TEQs. In the Strait of Georgia, PCCDs and PCDFs made a greater contribution to TEQs than non-ortho and mono-ortho PCBs, whereas the reverse was true for eggs outside the strait. Mean eggshell thickness was less than the pre-1947 value at all sites, although there was no significant relationship between eggshell thickness and DDE concentrations. Levels of other organochlorine pesticides and mercury were below those considered to be toxic.

Leeches as in situ biomonitors of chlorinated phenolic compounds. Part 2: Pulp mill investigations

Leeches ( Nephelopsis obscura Verrill) were evaluated as in situ biomonitors of chlorinated phenolic compounds in the Fraser River at Prince George, BC, downstream from three bleached kraft pulp mills practising chlorine dioxide (ClO 2) substitution. Five biomonitoring periods, of 7 days duration, were selected to cover a full range of seasonal river conditions. Leeches bioconcentrated tri- and tetrachlorinated phenolics (bioconcentration factors: 465–6000) in proportions similar to those present in both mill effluent and river water. Leeches showed 3,4,5-trichloroguaiacol (3,4,5-TCG) to be the most consistent tracer of bleached kraft mill discharge. Leeches provided direct evidence that increasing ClO 2 substitution reduces amounts of chlorinated phenolics accumulated by aquatic organisms, with sharp decreases observed at ClO 2 levels greater than 90%. This study suggests that leeches could be applied as routine biomonitors for environmental impact monitoring.

Anguilla anguillaL. Stress Biomarkers Recovery in Clean Water and Secondary-Treated Pulp Mill Effluent

The eels’ recovery from capture, anoxia, and transport is improved by the dechlorinated filtered aerated tap water temperature increase and increased water salinity. The eels’ 6-hr recovery from capture, anoxia, and transport, at 25°C in 50% secondary-treated bleached kraft pulp mill effluent, as plasma lactate and cortisol uptake, is depressed. However, either farm or wild eels’ exposure to the 50% secondary-treated bleached kraft pulp mill effluent, after 188 hr recovery from capture, anoxia, and transport, induces plasma lactate increase and prevents interrenal cortisol release to the blood, decreasing its plasma concentration.

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.

Isolation and characterization of resin acid degrading bacteria found in effluent from a bleached kraft pulp mill

Thirteen resin acid degrading bacteria enriched on abietic or dehydroabietic acids were isolated from waste water from the aerated stabilization basin of a bleached kraft pulp mill. Standard biochemical tests were used to characterize each isolate. Each isolate was tested for its ability to degrade six abietane- and pimarane-type resin acids. Resin acid concentrations were determined by high pressure liquid chromatography and UV absorbance. Cluster analysis based on phenotypic characteristics identified two distinct clusters of degraders that differed in their ability to utilize carbohydrates as carbon sources. Fatty acid methyl ester analysis of representative isolates from each cluster identified A19-6a and D11-13 as Comamonas and Alcaligenes species, respectively. To determine genotypic relatedness, enterobacterial repetitive intergenic consensus sequences were used to amplify genomic DNA fragments from 10 isolates. These results supported the phenotypic analysis for all isolates tested except A19-5 and A19-6b. These two organisms were clustered closely together based on phenotype but had distinctly different banding patterns, suggesting that they are not related genotypically. All isolates degraded a subset of the six resin acid congeners. Isolates A19-3, A19-6a, A19-6b, and D11-37 were the most effective at degrading all six congeners.