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As transcriptomic studies are becoming more and more common, it is important to ensure that the RNA used in the analyses is of good quality. The RNA integrity may be compromised by storage temperature or freeze-thaw cycles, but these have not been well studied in poikilothermic fishes. This work studied the effects of tissue storage time and temperature, and freeze-thaw cycles of tissue and extracted RNA on RNA integrity in brown trout (Salmo trutta L.) liver. The storage time and temperature had an effect on RNA integrity, but RNA suitable for quantitative reverse transcription PCR (RT-qPCR) (RIN > 7) was still obtained from samples preserved at − 20 °C for 6 months. Freeze-thaw cycles of tissue or RNA did not compromise the integrity of RNA. RNA degradation had an effect on RT-qPCR results, and the effect depended on gene. The RT-qPCR analysis of historical samples from a bleached kraft pulp mill effluent exposure in 1984 revealed no significant cyp1a induction. Recommendations are given for the preservation and handling procedures of samples designated for transcriptomic analyses. [ABSTRACT FROM AUTHOR]

Poly (lactic acid) (PLA) reinforced with bleached kraft soft wood (BKSW) biocomposites with fibre content up to 35% were processed by kinetic mixing and injection moulding. The cellulosic filler was a commercial chemical bleached kraft soft wood pulps composed of well individualized fibres free from lignin with diameter about 20 μm and length within micron scale. The effect of fibre addition on the thermal properties of composites was investigated using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermal gravimetric analysis (TGA) and thermo-mechanical analysis (TMA). In a previous work, it was demonstrated that fibre inclusion on PLA enhanced the modulus as well as the strength. Fibre addition promoted the crystallization of PLA by favouring the heterogeneous nucleation and accelerating the crystallization kinetic, without adversely altering the thermal stability. The DMA analysis confirmed the strong stiffening effect brought by the addition of fibres at the glassy as well as the rubbery domains. The presence of fibres had also a beneficial effect on the dimension stability by lowering the thermal expansion coefficient of composites. [ABSTRACT FROM AUTHOR]

A bleached kraft pulp mill in Nova Scotia has discharged effluent wastewater into Boat Harbour, a former tidal estuary within Pictou Landing First Nation since 1967. Fifty years of effluent discharge into Boat Harbour has created >170,000 m of unconsolidated sediment, impacted by inorganic and organic contaminants, including metal[loid]s, polycyclic aromatic hydrocarbons (PAHs), dioxins, and furans. This study aimed to characterize metal(loid)-impacted sediments to inform decisions for a $89 million CAD sediment remediation program. The remediation goals are to return this impacted aquatic site to pre-mill tidal conditions. To understand historical sediment characteristics, spatiotemporal variation covering ~quarter century, of metal(loid) sediment concentrations across 103 Boat Harbour samples from 81 stations and four reference locations, were assessed by reviewing secondary data from 1992 to 2015. Metal(loid) sediment concentrations were compared to current Canadian freshwater and marine sediment quality guidelines (SQGs). Seven metal(loid)s, As, Cd, Cr, Cu, Pb, Hg, and Zn, exceeded low effect freshwater and marine SQGs; six, As, Cd, Cr, Pb, Hg, and Zn, exceeded severe effect freshwater SQGs; and four, Cd, Cu, Hg, and Zn, exceeded severe effect marine SQGs. Metal(loid) concentrations varied widely across three distinct temporal periods. Significantly higher Cd, Cu, Pb, Hg, and Zn concentrations were measured between 1998 and 2000, compared to earlier, 1992-1996 and more recent 2003-2015 data. Most samples, 69%, were shallow (0-15 cm), leaving deeper horizons under-characterized. Geographic information system (GIS) techniques also revealed inadequate spatial coverage, presenting challenges for remedy decisions regarding vertical and horizontal delineation of contaminants. Review of historical monitoring data revealed that gaps still exist in our understanding of sediment characteristics in Boat Harbour, including spatial, vertical and horizontal, and temporal variation of sediment contamination. To help return Boat Harbour to a tidal estuary, more detailed sampling is required to better characterize these sediments and to establish appropriate reference (background) concentrations to help develop cost-effective remediation approaches for this decades-old problem. [ABSTRACT FROM AUTHOR]

Effects of dual-treatment on cellulose fiber quality, micro-structure appearance, crystalline structure, hydrogen bonds, and surface elements were analyzed using a fiber quality analyzer (FQA), scanning electron microscope (SEM), wide-angle X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS), respectively. In comparison to the untreated pulp, the brightness of pulp increased by 51.71%, whereas the apparent density and burst strength index of the pulpboard decreased by 11.76% and 48.18%, respectively. The absorption time, absorbability, and bulk of the fiber obtained by defibering the pulpboard decreased by 47.40%, 8.33%, and 5.32%, respectively, when it had been subjected to supplementary alkali. With the analysis of FQA and SEM, fiber swelled and curled, its surface was relatively smooth, and filaments of its partial surface area were exposed as a result of the supplementary alkali. Additionally, XRD analysis, FT-IR analysis, and XPS scanning spectra all showed that the crystallinity degree of fiber decreased by 45.10%, indicating more crystal structures were converted into amorphous structures. The proportion of total intra-molecular hydrogen bond intensity to total hydrogen bonds increased. The -OH content on fiber surface only decreased by 4.15%, compared with those of the untreated pulp, when the fiber was subjected to the two-step chemical treatment. [ABSTRACT FROM AUTHOR]

Improved regulations for pulp and paper mill effluents and an industry shift away from elemental chlorine bleaching in the 1990s greatly reduced the release of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) into the environment. However, the high potential of these contaminants to persist in sediment and bioaccumulate in biota means that they have remained a concern. To document current contamination from bleached kraft pulp mill effluent, PCDD/Fs were measured in white sucker ( Catostomus commersoni) collected from Jackfish Bay, Lake Superior. These values were contrasted to historically reported fish data as well as PCDD/F patterns from dated sediment cores. Patterns of PCDD/Fs in sediment cores from Jackfish Bay and reference sites demonstrated a relationship between contamination and mill process changes. During the peak PCDD/F contamination period (1991), when the mill was still using elemental chlorine, the contamination patterns in fish and sediment were distinct and dominated by 2,3,7,8-tetrachlorodibenzo- p-dioxin and 2,3,7,8-tetrachlorodibenzofuran. Following the reduction in the use of elemental chlorine during the early 1990s, a rapid decline was observed in PCDD/F contamination of fish tissue, and levels are now approaching background conditions with congener patterns more reflective of atmospheric sources. Although surface sediments from Jackfish Bay continue to have elevated PCDD/Fs, with some locations exceeding sediment quality guidelines, they do not appear to be highly bioavailable to benthic fish. Environ Toxicol Chem 2015;34:2489-2502. © 2015 SETAC [ABSTRACT FROM AUTHOR]

Lignin is a huge energy and carbon reserve but owing to its highly biologically recalcitrant nature it is commonly regarded as a waste in lignocellulosic biomass biorefinery. To realize the lignin biorefinery, it is proposed to use Kraft lignin, isolated from black liquor from Kraft pulping mills, as starting material to be fragmented by fast pyrolysis or selective catalysis to aromatic sub-units and to be post-refining with additional cleavage reaction and separation/purification as commodity aromatics pool in chemical industries. This Note calls for research efforts on detailed investigation of the feasibility of this proposed scenario. [ABSTRACT FROM AUTHOR]

The treatment of bleaching-effluent from pulp and paper industry was investigated in a batch electrocoagulation (EC) reactor using aluminium as sacrificial electrodes. The response surface methodology (RSM) was employed to evaluate the individual and interactive effects of four independent parameters viz., current density (j: 5-25 mA/cm2), initial pH (pHo: 5-9), electrolyte (NaCl) concentration (c: 0-2 g/L) and electrolysis time (t: 10-30 min) on Colour, COD and BOD removal efficiency. The results were analyzed using Pareto analysis of variance (ANOVA). Based on RSM analysis, a second-order polynomial regression model was developed and found to be good fit with experimental results. © 2011 American Institute of Chemical Engineers Environ Prog, 2011 [ABSTRACT FROM AUTHOR]

Abstract: The study reported in this paper tested the hypothesis that the developmental and reproductive health of mosquitofish (Gambusia affinis) exposed to pulp and paper effluent in the Dengcun River would differ from that of mosquitofish living in a reference site. We also studied whether morphological characteristics such as the anal fin and hemal spines of mosquitofish could serve as indicators for evaluating the androgenic effect and mosquitofish population security in the Dengcun River. Male and female mosquitofish were captured at three sites contaminated by pulp and paper effluent in the Dengcun River in Sihui, South China, and at a nearby uncontaminated reference site. Samples were collected from the sampling sites on the same day in August 2009. We compared the populations by total length, wet body and liver mass, gonad mass, and population composition. We also compared the populations according to number of anal fin segments, oocyte and embryo count, anal fin and hemal spine morphology among females, and by sperm count and viability among males, and observed the gonadal and liver histology of both males and females. Female mosquitofish exposed to pulp and paper effluent in the Dengcun River were generally smaller in length and mass, had a greater number of anal fin segments and more embryos, but had significantly fewer oocytes in comparison with those living at the reference site. The higher number of anal fin ray 3 segments and the increased ray 4:6 length ratio observed among fish taken from the Dengcun River sites indicated that they might be subject to the androgenic effect. Furthermore, the significantly different hemal spine morphology of the effluent-affected females also indicated the pulp and paper mills effluents in Dengcun River might contain androgenic substance(s). Male mosquitofish at the sites exposed to effluent had a higher number of anal fin segments and greater testis mass in comparison with those living at the reference site. No evidence of intersex was found in either males or females, although histopathological tests on females revealed histologic abnormalities in the liver and gonads. It can be concluded that pulp and paper effluent contamination in the Dengcun River has affected a number of developmental parameters and reproductive characteristics in mosquitofish, with possible adverse effects on reproduction in this population. [Copyright &y& Elsevier]

Abstract: A synergistic action of xylano-pectinolytic enzymes from the same bacterial isolate Bacillus pumilus was evaluated for the prebleaching of kraft pulp. The enzymatic prebleaching of kraft pulp resulted in 8.5% reduction in kappa number of the pulp, showing remarkable delignification with the enzyme treatment. This approach resulted in 25% reduction in active chlorine consumption in subsequent bleaching stages without any decrease in brightness. Increase in Burst factor (9%), Tear factor (4.6%), Breaking length (4.4%), Double fold number (12.5%), Gurley porosity (4%) and Viscosity (11.8%) of enzyme treated pulp reflected the significant improvement in pulp properties. This is the first report describing the use of xylanase and pectinase produced simultaneously in the same production medium from the same bacterial isolate for effective biobleaching of kraft pulp. Use of this xylano-pectinolytic synergism in paper and pulp industry will ultimately help in making the process not only economically feasible but also eco-friendly. [ABSTRACT FROM AUTHOR]

Background, aim and scope Pulp and paper mills generate a plethora of pollutants depending upon the type of pulping process. Efforts to mitigate the environmental impact of such effluents have been made by developing more effective biological treatment systems in terms of biochemical oxygen demand, chemical oxygen demand, colour and lignin content. This study is the first that reports an evaluation of the effects of a tertiary treatment by fungi (Pleurotus sajor caju, Trametes versicolor and Phanerochaete chrysosporium and Rhizopus oryzae) on individual organic compounds of a Eucalyptus globulus bleached kraft pulp and paper mill final effluent after secondary treatment (final effluent). Material and methods The tertiary treatment with P. sajor caju, T. versicolor and P. chrysosporium and R. oryzae was performed in batch reactors, which were inoculated with separate fungi species and monitored throughout the incubation period. Samples from effluent after secondary and after tertiary treatment with fungi were analysed for both absorbance and organic compounds. The samples were extracted for organic compounds using solid-phase extraction (SPE) and analysed by gas chromatography- mass spectrometry (GC/MS). The efficiencies of the SPE procedure was evaluated by recovery tests. Results A total of 38 compounds (carboxylic acids, fatty alcohols, phenolic compounds and sterols) were identified and quantified in the E. globulus bleached kraft pulp mill final effluent after secondary treatment. Recoveries from the extraction procedure were between 98.2% and 99.9%. The four fungi species showed an adequate capacity to remove organic compounds and colour. Tertiary treatment with R. oryzae was able to remove 99% of organic compounds and to reduce absorbance on 47% (270 nm) and 74% (465 nm). P. sajor caju, T. versicolor and P. chrysosporium were able to remove 97%, 92% and 99% of organic compounds, respectively, and reduce 18% (270 nm) to 77% (465 nm), 39% (270 nm) to 58% (465 nm) and 31% (270 nm) to 10% (465 nm) of absorbance, respectively. Discussion The wide variety of organic compounds found in the final effluent must be due to the degradation of E. globulus wood in pulp and paper mill. The concentrations of organic compounds in the final effluent of E. globulus bleached kraft pulp mill were in residual levels maybe due to the secondary treatment. The recovery tests showed the effectiveness of the extraction procedure, and no losses of analyte were suspected in the analytical determinations. Lignin derivatives such as vanilic acid, syringic acid, guaiacol, syringol and phloroglucinol were totally removed by R. oryzae, but the 47% absorbance reduction obtained at 270 nm suggests that these species were not able to complete degradation of lignin macromolecular compounds. Conclusions The organic compounds (carboxylic acids, fatty alcohols, phenolic compounds and sterols) were removed more efficiently by tertiary treatment with R. oryzae or P. chrysosporium, followed by P. sajor caju and T. versicolor. Regarding the removal of both colour and organic compounds, the tertiary treatment with R. oryzae was the most efficient. Recommendations and perspectives In order to reduce the deleterious impacts of paper mill effluents, efforts have been made to develop more effective advanced tertiary treatments. This study may serve as a basis of characterisation, in terms of organic compounds of E. globulus bleached kraft pulp mill final effluent after secondary treatment and as an effort to understand the effects of tertiary treatments with fungi on low concentrations of organic compounds from biological secondary treatment. [ABSTRACT FROM AUTHOR]

Pulp and paper mill effluents may cause harmful effects to the aquatic environment due to the combined influence of physical factors, toxic compounds, and nutrient enrichment. In the present study, the effectiveness of secondary treatment in reducing the toxicity of an elemental chlorine-free bleached-kraft pulp mill effluent was evaluated. To characterize the toxicity of the effluent, before and after the implementation of secondary treatment, a battery of tests with organisms bearing different functions at the ecosystem level was used, namely Vibrio fischeri (5-min luminescence), Pseudokirchneriella subcapitata (72-h growth), Lemna minor (7-day growth), Daphnia magna (21-day reproduction and 24-h postexposure feeding), Chironomus riparius (9-day growth), and Danio rerio (28-day growth). For the effluent sample collected before the implementation of secondary treatment, P. subcapitata was the most sensitive organism followed by V. fischeri and D. magna, and no toxic effects were observed toward the other organisms. For the effluent sample collected after the implementation of secondary treatment, the effluent caused no toxic effects on any of the tested species. The present results demonstrated not only that secondary treatment efficaciously reduced effluent toxicity toward the selected test organisms but also the usefulness of a battery of tests to characterize the toxicity of pulp mill effluents. [ABSTRACT FROM AUTHOR]

Huge efforts have been made both in adopting more environmental-friendly bleaching processes, and in developing advanced oxidation processes and more effective biological treatments for the reduction of deleterious impacts of paper mill effluents. Even so, the success of such treatments is frequently reported in terms of chemical parameters without a proper evaluation of the effluent's toxicity mitigation. This is the first study reporting an exhaustive evaluation of the toxicity of a secondary bleached kraft pulp mill effluent, after either tertiary treatment with the soft-rot fungi Rhizopus oryzae or with a photo-Fenton oxidation, using a battery of freshwater species. As it has been reported the photo-Fenton/UV treatment has proved to be the most effective in reducing the colour and the COD (chemical oxygen demand) of the effluent. Nevertheless, extremely low EC50 values were reported for almost all species, after this tertiary treatment. The treatment with R. oryzae was less effective in terms of colour removal and COD reduction, but proved to be the most promising in reducing toxicity. [Copyright &y& Elsevier]

Abstract: The presence of unidentified estrogens and androgens in effluents from pulp and paper mills is well documented. However, their role in effluent effects on fish reproduction remains unclear. The objective of this study was to investigate the hypothesis that reproductive impacts of a modern pulp mill effluent are mediated by androgens and/or estrogens in the effluent. Male and female threespine stickleback were exposed to biologically treated Canadian bleached kraft mill effluent under flow-through conditions in the laboratory at 0, 1, 10 and 100% (v/v) dilutions. After 7 and 21 d of exposure, steroidogenesis was assessed using in vitro incubations of gonadal tissue in both males and females. mRNA expression of the estrogen-regulated gene vitellogenin, and the androgen-responsive gene spiggin were assessed using quantitative RT-PCR in the livers of male and posterior kidneys of female stickleback, respectively. Hepatic 7-ethoxyresorufin-O-deethylase (EROD) activity was assessed in both sexes. Effluent extracts were examined for estrogenic and androgenic bioactivity using receptor binding bioassays, and were screened for pulp and paper related extractives and steroidal androgens using GC–MS. This effluent up-regulated spiggin mRNA in the kidney of female stickleback at 10% and 100% (v/v) effluent at 21 d, but not at 7 d of exposure. This change at the mRNA expression of the gene was associated with an increase in cell height in kidney proximal tubule epithelial cells at 100% effluent after both 7 and 21 d. Liver vitellogenin mRNA in male stickleback was not induced at either 7 or 21 d. EROD was induced at 10 and 100% after 21 d of exposure in both sexes, but not after 7 d of exposure. Despite evidence of exposure to androgens, there was no reduction in steroidogenic capacity at any effluent dilution. Effluent extracts were capable of eliciting the displacement of androgens and estrogens from receptors, but androgenic potency was 4-fold greater. A screen of more than 30 androgenic androstane steroids showed no detections. Hence, the androgenic constituents in this particular effluent remain unknown. [Copyright &y& Elsevier]

In order to recover and reuse water in the Kraft mill process, evaluation of separate streams is required to identify toxic compounds or microcontaminants. The stage E1 Kraft effluent, corresponding to the first extraction step of the bleaching Kraft mill process, provides the main toxic compounds found in the final process effluent. This paper uses the toxicity identification evaluation (TIE) procedure for the physicochemical and ecotoxicological characterization of the E1 Kraft effluent. To distinguish the most important toxic compounds, a physicochemical characterization and Phase I of the TIE procedure were performed. The acute toxic effect of the E1 Kraft effluent and treated fraction was performed on Daphnia magna. Results show that untreated E1 Kraft effluent exerts an acute toxic effect on D. magna (24 h LC50 = 27.6%), where the E1 Kraft effluent is characterized by pH 10.5, chemical organic demand (COD) 1,348.8 mg/l, and biological organic demand (BOD5) 397.5 mg/l, while total phenolic compounds and color are 853.7 mg/l and 0.204 1 × 1 cm, respectively. Additionally, Cu+2 (0.51 mg/l) and Fe+2 (0.64 mg/l) were detected. With respect to different treatments, our results indicate that activated carbon, anionic and cationic exchange treatments were able to reduce more that 45% of E1 Kraft effluent's acute toxicity and that the ethylenediaminetetraacetic acid treatment was able to reduce the E1 Kraft effluent's acute toxicity to around 75% and the Cu+2 concentration to 0.019 mg/l. Moreover, specific analysis of heavy metals and organic compounds by GC-MS show that the main compound responsible for the toxicity was Cu+2, whose tolerance level on D. magna of the 0.12 mg/l. [ABSTRACT FROM AUTHOR]

Two enzyme treatments involving xylanase (X) and laccase (L) were used jointly in an XLE sequence (where E denotes alkaline extraction) to bleach oxygen-delignified eucalyptus kraft pulp in the presence of 1-hydroxybenzotriazol (HBT) as mediator. The results of the XLE sequence were compared with those of an LE sequence. The application conditions for the laccase–mediator system were optimized by using a sequential statistical plan involving three variables (viz., the laccase and mediator doses, and the reaction time) with both sequences. The models used to predict the kappa number and brightness revealed that, once all accessible lignin was removed, the system altered other coloured compounds. The best conditions for the L stage involved a reduced mediator dose (0.5% odp). The xylanase pretreatment increased the accessibility of residual lignin and facilitated removal of hexenuronic acids. For a specific target brightness level of 70% ISO, the X pretreatment can save as much as 30% laccase and 80% mediator while shortening the reaction time by 45%. [Copyright &y& Elsevier]

Large volumes of wastewater with a high organic load are generated by the pulp and paper industry that negatively affect the quality of receiving waters. The main waste products in the pulp mill effluents are lignin derived macromolecular compounds, which are similar to natural humic substances and very resistant to wastewater treatments. Fulvic acids (FA) represent the higher percentage of these humic substances and it was observed that solar irradiation modify their properties. Several analytic tools, namely, UV–Visible, molecular fluorescence and FTIR spectroscopies, were used to assess the effect of solar exposition on fulvic acids from a kraft pulp mill effluent. It may be concluded that sun irradiation may alter to a high extent the physicochemical properties of macromolecular organic matter, namely fulvic acids, released by kraft pulp mill effluents. After solar exposition, the aromaticity decreases, the aliphatic structures become more oxygenated, and the fulvic acids from the pulp mill effluent remaining in solution are more similar to aquatic fulvic acids from non polluted sites. [Copyright &y& Elsevier]

Paper mill effluents may contain polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) that are normally generated due to chlorinated bleaching of pulp and paper. We used the semipermeable membrane device (SPMD) to monitor PCDD/F levels upstream and downstream of a paper mill on the Androscoggin River, in Jay (ME). Following the 36 day deployment, SPMD dialysis and cleanup, the samples were analyzed by HRGC/HRMS. Total concentrations of PCDD/Fs in SPMDs (sum of all tetra-through octachlorinated congeners) ranged from 4.71pgg−1 to 26.26pgg−1. Five out of the targeted 17 toxic congeners were detected, including: 2,3,7,8-TCDF; 1,2,3,7,8-PeCDF; 2,3,4,7,8-PeCDF; 1,2,3,4,6,7,8-HpCDD and OCDD. Permeability reference compounds (PRCs) were used for in situ calibration of the SPMD sampling rate (R s). In all sites, water concentrations were the highest for OCDD (0.081–0.103pgl−1), and the lowest for 1,2,3,7,8-PeCDF (0.005–0.009pgl−1). There was not a consistent pattern of upstream–downstream gradient in the PCDD/F levels. This suggested that processes other than the mill in Jay (multiple sources, river dynamics) governed the flux of PCDD/Fs in the sampling locations. The SPMD results were validated by comparison to other studies on the Androscoggin River and elsewhere, confirming the potential of the device as a useful monitoring technique for PCDD/Fs in large river systems. [Copyright &y& Elsevier]

Reactor studies of aerobic degradation of effluent from the first and last ponds of the treatment system of two New Zealand pulp and paper mills indicated that filterable BOD5, resin acids and transformed resin acids, free and bound, degraded at similar rates. During oxidative treatment the resin acids of untreated effluent became increasingly bound to particulate material and a sediment high in abiet-13-enoic acid was formed. [ABSTRACT FROM AUTHOR]

The impact of ozone oxidation on removing high molecular weight (HMW) organics in order to improve the biodegradability of alkaline bleach plant effluent was investigated using a semi-batch reactor under different initial pH (12 and 7). After the ozonation process, the ratio of BOD5/COD increased from 0.07 to 0.16 and 0.22 for initial pH 12 and 7, respectively. Also, the effluent color decreased by 48% and 61% at initial pH 12 and pH 7, respectively. These changes were primarily driven by reductions of the HMW fractions of the effluent during ozonation. [ABSTRACT FROM AUTHOR]

A dark and complex salified organic polymeric mixture, named lignimerin, was for the first time recovered from Kraft cellulose mill wastewater (KCMW) and characterized by chemical, spectroscopic and relative molecular weight (RMW) analysis. Lignimerin proved to be composed of polyphenols (57.00%), carbohydrates (22.26%) and proteins (7.42%). It also contained metals (6.93%), mainly Ca and, to much lower extent, Mg, Na, Al, Fe, K, Mn, Zn and Cu, bound to the carboxylate and phenate groups. The distribution of lignimerin RMW was assessed to be approximately between 1000 and 8600Da, as well as to consist of lignin and tannin, protein and polysaccharide moieties, strongly aggregated each other. H-lignimerin, its acid derivative, revealed a chemical composition and a RMW distribution very close to that of lignimerin, but a marked metal cations decreasing (1.60%) with respect to lignimerin (6.93%). The humic acid-like nature of both the polymers was assessed. Their potential use as bio-adsorbents of heavy metals is briefly discussed. [Copyright &y& Elsevier]

The effect of temperature fluctuations on bacterial community structure and function in lab-scale sequencing batch reactors treating bleached kraft mill effluent was investigated. An increase in temperature from 30 to 45°C caused shifts in both bacterial community structure and function. Triplicate reactors were highly similar for 40 days following startup. After the temperature shift, their community structure and function started to diverge from each other and from the control. A multi-response permutation procedure confirmed that the variability in community structure between transient and control reactors were greater than that among the triplicate transient reactors. The fact that these disturbances manifest themselves in different ways in apparently identical reactors suggests a high degree of variability between replicate systems. [Copyright &y& Elsevier]

Mechanically aerated lagoons (used for wastewater treatment in the pulp and paper industry) are typically very large (> 500,000 m³) and have complex three-dimensional fluid flow patterns due to mechanical agitation, sludge accumulation, internal baffling, and confined inlet/outlet flow channels. RTD data is frequently used for evaluation of hydraulic performance, however, obtaining accurate data with traditional dye measurements is a difficult and time-consuming process. Moreover, the mixing impact of factors such as aerator positions, sludge accumulation, and internal baffles would require a significant and costly number of local field measurements. Recent applications of CFD to mechanically aerated lagoons have helped engineers to understand the complex flow interactions. This paper provides a practical method for the evaluation of the hydraulic performance of large mechanically aerated lagoons using CFD. A method, based on random-walk Lagrangian particle tracking, has been developed to significantly shorten the computational time needed to produce RTD curves for these lagoons. Comparison of the particle method with the more conventional scalar transport yields excellent results. These methods allow wastewater engineers to combine their existing knowledge and expertise with the established power of CFD. The results quantify the hydraulic impact of different inlet/outlet configurations, aerator configurations, influent flow rates, and bottom sludge profiles. [ABSTRACT FROM AUTHOR]

The biodegradability of four novel diethanolamine derivative complexing agents was examined by using two biodegradation tests standardised by OECD (301B and 301F). Ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) were employed as reference substances. Biodegradation of the new complexing agents was studied both with unacclimated and acclimated inocula as well as by simulating wastewater treatment in sequencing batch reactors (SBRs). These new complexing agents were of technical grade, and therefore, the results are only indicative but these new compounds hold promise for use as complexing agents in the pulp and paper industry. The novel complexing agents were not readily biodegradable but they showed slight biodegradation. Around 10–30% degradation was found in the SBR where degradation was followed by measurement of concentration. Moreover the novel complexing agents did not have any negative impact on reactor performance as measured by chemical oxygen demand reduction. In the standardised biodegradation tests at best around 50% degradation was observed with the acclimated inoculum and in the prolonged test whereas EDTA and DTPA exhibited no biodegradation. The elevated degradation in acclimated sludge indicates that the water treatment plant microbes are capable of decomposing these molecules under favourable conditions. The total concentration of novel complexing agents decreased slightly during biodegradation tests, while the EDTA and DTPA concentrations remained stable. [Copyright &y& Elsevier]

Past studies at a bleached kraft pulp mill located in Saint John, NB, Canada have shown that chemical recovery condensates significantly depress circulating and gonadal steroids in mummichog (Fundulus heteroclitus), an endemic fish species. In the present study, compounds were extracted from the condensates, and a toxicity identification evaluation (TIE) was conducted to characterize the hormonally active substances (HASs) in the condensates. Extracts were fractionated by high performance liquid chromatography (HPLC) and mummichog were exposed to the fractions in a 7-day bioassay. Plasma testosterone was measured for each sex following exposure. Responses in fish exposed to the whole extract at 1% v/v were not as pronounced as had been observed previously (female plasma testosterone was reduced by 16% in the current study compared to 75% previously). Dose–response experiments showed an exposure concentration of 4% v/v was required to elicit significant plasma steroid reductions. Despite these responses, individual condensate fractions actually increased steroid levels in mummichog, which suggests that multiple HASs may need to act synergistically or additively to elicit effects, and if separated, the compounds may have different hormonal activity. The HASs in question caused a reduction in male gonad size at 4% v/v, and have sex-dependent mechanisms of action (males were more responsive to exposure than females). [Copyright &y& Elsevier]

The effect of ozonation process on pulp and paper mill effluents was investigated. The objectives were to: (1) identify various compounds in wastewater from a pulp and paper mill, (2) evaluate decolorization and organic removal efficiency by conventional bubble reactor and (3) evaluate the biodegradability at various progressive stages of ozonation. The qualitative GC/MS analyses were performed before and after the biological treatment and ozonation process. Two groups of compounds were observed in this wastewater: lignin-derived compounds and aliphatic compounds used in the pulp and paper production process (i.e. n-alkanes, fatty alcohols, fatty acid and ester). Treatment efficiency was measured by decolorization and TOC removal rates. Additionally, the utilization coefficient (k) and BOD/COD ratio were determined to observe the biodegradability of ozonized effluents. The results indicated that after 45min, the ozonation of effluents yielded almost colorless effluent with over 90% decolorization efficiency and with corresponding ozone capacity rate of 20. 0mgO3 L−1. This decolorization was not always accompanied by the mineralization of the organic matters therefore ozonation was not related to TOC removal rates. The BOD/COD ratio increased from 0. 10 to a maximum value of 0. 32 with ozone flow rate (O/F) of 4. 0Lmin−1. It was confirmed by the utilization coefficient as first order BOD equation, the magnitude k value increased from 0. 21day−1 to maximum value of 0. 47day−1 as the ozonation time was raised to 60min with O/F 4. 0Lmin−1. [Copyright &y& Elsevier]

In this study a poorly biodegradable (BOD/COD = 0.3) industrial alkaline ECF bleaching filtrate was treated using different advanced oxidation processes to evaluate their use in combined chemical-biological treatment aimed at increasing recalcitrant COD removal and improving final effluent quality. Oxidative treatments included ozonation combined with hydrogen peroxide (2, 5, 10, 20 mmolL-1 O3/0.7, 2, 5, 10 mmolL-1 H2O2) and photocatalysis with hydrogen peroxide (UV/2, 4 and 8 mmolL-1 H2O2) and with T1O2 (UV/TiO2/0.7 and 4 mmolL-1 H2O2). The O3/H2O2 process increased effluent biodegradability by up to 68% as a result of increasing BOD and decreasing COD. Increasing the O3 dose had a greater effect on biodegradability improvement and lignin and colour removal efficiencies than increasing the H2O2 dose. A combined oxidant dose of 5 mmolL-1 O3 and 2 mmolL-1 H2O2 resulted in 75% lignin removal, 40% colour removal and B% carbohydrate loss without mineralizing the organic carbon. The photocatalytic processes led to a decrease in effluent biodegradability through combined decrease in BOD and increase in COD and did not result in efficient lignin or colour removal. Photocatalytic oxidation was apparently inhibited by the high chloride and COD levels in the alkaline filtrate, and may be more efficient in recalcitrant COD removal if performed after biological. [ABSTRACT FROM AUTHOR]

The objective of this paper is to identify deflocculation under short-term disturbances of dissolved oxygen (DO) in a continuous system, and to explore the strategies for minimizing the carry-over of biosolids. Sludge deflocculation was examined in four parallel sequencing batch reactors (SBRs) fed with primary treated effluents from a bleached kraft pulp and paper mill. Results show that the DO transients caused a reduction of soluble COD (SCOD) removal efficiency by 50-70%, increases in suspended solid (SS) concentration and turbidity by more than 100%. Under the DO disturbances, the ratio of bulk Ca2+/K+ decreased by 10% in the treated effluents. All these changes were reversible within 24 hrs alter the DO concentrations were restored up to 4 rag/L, indicating a physicochemical response of microorganisms to the DO transients. The sludge deflocculation is correlated with the decreasing ratio of Ca2+ to K+ in the extracellular environment. Addition of calcium chloride, tetraethytammonium chloride or glibenclamide promotes the formation of bioflocs bigger than 12.5 µm, but the deflocculation of biosolids under the DO transients wasn't completely prevented. [ABSTRACT FROM AUTHOR]

The pulp and paper industry has invested heavily over recent years in cleaner processing, to reduce losses and minimise its impact on the environment. Over the past fifteen years, a New Zealand integrated bleached kraft mill has undergone a comprehensive programme of upgrades to increase production, reduce water consumption and streamline its biological treatment process. Whilst the overall discharge of contaminants from the site decreased, the treatment system performance did not show a concurrent improvement as may have been expected. Reduced BOD removal, low dissolved oxygen levels, and poor solids settlability were symptomatic of phosphorus limitation in the aerated lagoon treatment system. The wastewater entering the system was found to be phosphorus limited at a BOD:P ratio of 100:0.2. Mono-ammonium-phosphate was supplemented, at approximately 30 kg P/d, to raise the phosphorus levels to a BOD:P ratio of 100:0.3. Treatment efficiencies improved very quickly after phosphorus dosage, with a 50% reduction in BOD and TSS discharge, a significant increase in dissolved oxygen levels, and improved BOD removal (85% to 93%). This case study demonstrates that whilst more closed operation can result in reduced discharge of organic loads, there may be negative impacts on the availability of nutrients for balanced biological growth. [ABSTRACT FROM AUTHOR]

Effectiveness of ozonation before and after biological treatment for removal of recalcitrant organic matter in bleached kraft pulp effluents was compared. Two industrial ECF bleached eucalypt kraft pulp effluents (E 1 and E2) were pretreated with 100 mg O3/L. Raw and pretreated effluents were treated biologically in bench-scale sequencing batch reactors, under constant conditions, Following biological treatment, effluents were post-treated with 100 and 200 mg O3/L. Effluent pretreatment increased effluent biodegradability by 10% in E1 and 24% in E2. Combined O3-biological treated led to small but significant increases in COD, BOD and lignin removal over biological treatment alone, but pretreatment had no significant effect on effluent colour and carbohydrate removal. Ozone pretreatment did not affect biological activity during treatment of effluent E1 but resulted in a 38% lower specific oxygen uptake rate in effluent E2. At an equivalent dose of 100 mg/L, pre-ozonation produced better quality effluent than post-ozonation, especially with regard to COD and colour. Likewise, when an equivalent dose of 200 mg/L was applied, splitting the dose equally between pre- and post-treatments was more efficient than applying the entire dose in the post-treatment. The potential for combined chemical-biological treatment to improve effluent quality has been confirmed in this study. [ABSTRACT FROM AUTHOR]

Up to 30% of the released colour arising from bleached kraft pulp and paper production comes from the alkaline extraction stage. This waste stream can therefore be readily targeted to remove colour at source in mills where improved colour management is required. The efficacy of five advanced oxidative treatment and physico-chemical technologies in removing colour from a typical Eop stage effluent was compared, The most effective oxidative treatment was peroxymonosulphate (79% colour removal in 15 minutes). Ozone and TAML® treatments removed 74% and 58% of colour respectively within 30 minutes. In comparison, hydrogen peroxide alone was only able to remove 35% of the colour over 4 hours. Coagulation with polyaluminium chloride achieved 89% colour removal within 5 minutes. However, this treatment produced an undesirable sludge, and may cause toxicity in the treated wastewater. Overall, colour removal ability of the five technologies ranked from highest to lowest was polyaluminium chloride > peroxymonosulfate > ozone > TAML® > hydrogen peroxide. Other factors, such as operating costs, feedstock modification and capital infrastructure, also need to be taken into account when selecting the most suitable colour management option. [ABSTRACT FROM AUTHOR]

This study reports on a multivariate analysis of the moving bed biofilm reactor (MBBR) wastewater treatment system at a Canadian pulp mill. The modelling approach involved a data overview by principal component analysis (PCA) followed by partial least squares (PLS) modelling with the objective of explaining and predicting changes in the BOD output of the reactor. Over two years of data with 8'7 process measurements were used to build the models. Variables were collected from the MBBR control scheme as well as upstream in the bleach plant and in digestion. To account for process dynamics, a variable lagging approach was used for variables with significant temporal correlations. It was found that wood type pulped at the mill was a significant variable governing reactor performance. Other important variables included flow parameters, faults in the temperature or pH control of the reactor, and some potential indirect indicators of biomass activity (residual nitrogen and pH out). The most predictive model was found to have an RMSEP value of 606 kgBOD/d, representing a 14.5% average error. This was a good fit, given the measurement error of the BOD test. Overall, the statistical approach was effective in describing and predicting MBBR treatment performance. [ABSTRACT FROM AUTHOR]

The hot acid hydrolysis followed by chlorine dioxide (A/D*) and hot chlorine dioxide (D*) technologies have proven very useful for bleaching of eucalyptus kraft pulp. Although the characteristics and biodegradability of effluents from conventional chlorine dioxide bleaching are well known, such information is not yet available for effluents derived from hot acid hydrolysis and hot chorine dioxide bleaching. This study discusses the characteristics and biodegradability of such effluents. Combined whole effluents from the complete sequences DEpD, D*EpD, A/D*EpD and ADEpD, and from the pre-bleaching sequences DEp, D*Ep, A/D*Ep and ADEp were characterized by quantifying their colour, AOX and organic load (BED, COD, TOG), These effluents were also evaluated for their treatability by simulation of an activated sludge system. It was concluded that treatment in the laboratory sequencing batch reactor was efficient for removal of COD, BOD and TOG of all effluents. However, colour increased after biological treatment, with the greatest increase found for the effluent produced using the AD technology. Biological treatment was less efficient at removing AOX of effluents from the sequences with D*, A/D and AD as the first stages, when compared to the reference D stage; there was evidence of the lower treatability of these organochlorine compounds from these sequences. [ABSTRACT FROM AUTHOR]

study was undertaken to remove colour from a kraft mill's treated effluent in Kenya and determine the suitability of phosphate rock to replace wood ash during the electrochemical process. The electrochemical method alone, electrochemical combined with alum (ELCAL), wood ash leachate (ELCAS) and phosphate rock (ELPHOS) solutions at a rate of 165 to 1,000 g/m³ were tested. Effluent characteristics were determined after complete removal of colour. Same reduction rates of TS (85%) and TSS (89%) were recorded by ELCAS and ELPHOS. However, ELPHOS removed more COD (86 to 91%) and more BOD (85 to 92%) than ELCAS. Furthermore, the pH of ELPHOS treated solution was 9.3, within the Kenya Local Government's allowable limit. Power reduction with ELCAS and ELPHOS varied between 53 to 73% and 49 to 69% respectively but the difference was not statistically significant. Overnight aeration further improved the quality of ELCAS and ELPHOS treated effluent, reducing BeD and COD values to 0 mg/I. ELPHOS cost ($0.29/m³) was nevertheless three times higher than that of ELCAS ($0.10/m³), mainly because of free wood ash. ELPHOS did not also increase effluent phosphorus. It was therefore recommended that various ways be explored in making ELPHOS more economical to replace ELCAS. [ABSTRACT FROM AUTHOR]

We evaluated the effect of a catecholate chelator as a redox agent in Fenton-based reactions (known as chelator-mediated Fenton reaction—CMFR), in the presence of three different transition metals ions (Fe2+, Fe3+ and Cu2+) by determining the oxidative capability of CMFR towards lignin-model substrates. The potential application of mediated Fenton-based reactions as a novel process to treat pulp mill effluent was evaluated and monitored by chemical oxygen demand (COD) and total phenol removals from a combination of the effluents generated during an ECF bleaching stage. The catecholate chelator 3,4-dihydroxiphenilacetic acid (DOPAC) reduced both Fe3+ and Cu2+, in addition, the maximum Cu2+ reduction activity was reached in a shorter time than for Fe3+ reduction, however, the highest metal reduction activity was observed with Fe3+. When DOPAC was added to Fenton-based reactions (Fe3+/H2O2, Fe2+/H2O2, Cu2+/H2O2) an increase in oxidative activities of these reactions were found as they resulted in great degradation improvement of the lignin-model substrates azure B, phenol red and syringaldazine. The same increase in oxidative capability of Fenton-based reactions in the presence of DOPAC was observed after effluent treatment, expressed by the increase in COD removal, namely, an increase in the range of about 70% in COD removal when Fe2+ or Fe3+ was the catalytic metal and about 25% for Cu2+. However CMFR lead to an increase in total phenol content. As COD removal by CMFR system using Fe3+ and Fe2+ was not significantly different and that Fe3+ ions promoted lesser increase in total phenol content, Fe3+ was chosen for experimental optimization. At optimum conditions, 75% of COD and 30% of total phenol removal were achieved. [Copyright &y& Elsevier]

The Llobregat River is a basic drinking water resource for the city of Barcelona, meeting 40% of the demand, The river runs through a densely populated industrial area, so that it has in its history experienced various episodes due to industrial spills. The present work deals with a recent episode involving diacetyl. To the best of our knowledge this episode is the first time that this compound has been identified as an odour-causing compound in water, In a previous work the analytical method used for the identification of the compound causing the episode was described. The present work focuses its attention on how the episode was handled: action taken at the Sant Joan Despi water treatment plant and the sampling strategy on the river that led to the identification of the company responsible for the spill, a paper mill. It also deals with the role played by the FPA panel in the resolution of the episode: organoleptic description of samples of the problem in the initial phase of the episode (from the treatment plant, distribution network and customer complaints) and, once the compound responsible was identified, the determination of its organoleptic characteristics (odour threshold, odour descriptors, Weber-Fechner curve). [ABSTRACT FROM AUTHOR]

This article discusses the use of mold fungus, Aspergillus fumigatus, to produce xylanase enzymes to bleach paper residue from a pulp paper mill. The authors argue that reducing the amount of bleach in pulp paper mill effluent could reduce the formation of organochlorine pollutants and improve aquatic photosynthesis. This process could also decrease the formation of compounds and wood preservatives methyl mercaptan, pentachlorophenol and sodium pentachlorophenate some of which are toxic to fish. Purified xylanase used as a prebleaching agent improved paper quality and reduced chemical usage. Brightness, Kappa number, burst capacity, bulkness, and thickness of the pulp indicated paper quality.

Using gas-chromatographic analysis, the suitability of liquid–liquid extraction and solid-phase extraction (SPE) methods was studied for the rapid separation of resin and fatty-acid fractions from papermaking process waters. In the second phase of this study, a novel procedure (correlation coefficient >0.99 and repeatability RSD <8%) for on-line monitoring of selected individual acid components (limits of detection 11–78 µg L-1) by SPE combined with atmospheric pressure chemical ionization–mass spectrometry was developed. The suitability of this technique for quality control of papermaking process waters was tested by means of industrial samples. The method was also found suitable for the analysis of resin and fatty acids in receiving waters of pulp and paper mills. [ABSTRACT FROM AUTHOR]

Abstract: Two different effluents from the D1 and E1 stages of the ECF bleaching of Eucalyptus globulus kraft pulp were treated by catalytic hydrogenation in a trickle bed reactor using commercial and homemade Pd/AC catalysts. The reactor was fed with the bleaching effluent and a H2/N2 gas stream. The variables studied were space-time (1. 4–5gcat min/mL), gas to liquid flow ratio (286–1000vol. ), gas feed concentration (H2:N2, 1:1–1:7. 3vol. ), temperature (25–100°C) and pressure (1–11bar). Hydrotreatment performance was evaluated in terms of ecotoxicity, adsorbable organic halogen (AOX), chemical oxygen demand (COD), biological oxygen demand (BOD5) and colour removal. In all the runs, the ecotoxicity of the effluents decreased as a result of the treatment, achieving reductions that ranged from 70% to 98%. Simultaneously to the reduction of toxicity, the hydrotreatment led to a decrease of the colour of the effluents, being the decrease significantly higher in the case of E1 effluent. The AOX content was reduced by 85% and 23% for E1 and D1 effluents, respectively. In the case of D1 effluent the removal of ecotoxicity was significantly higher than that of AOX, which indicates that much of the toxicity of the effluent must be associated to non-chlorinated organics. In spite of the important reduction of ecotoxicity, the biodegradability of the effluents only increased slightly. The homemade catalysts, prepared from activated carbons with a high external or non-microporous surface area and mesopore volume and a convenient surface chemistry showed a higher efficiency than the commercial one. [Copyright &y& Elsevier]

The efficiency of an ozonation process in the degradation of the Kraft E1 effluent was evaluated. The investigation was focused on the reduction of chemical oxygen demand, total phenols, color and the absorbance at 254 nm. The chronic toxicity was evaluated by growth inhibition of algae Selenatrum capricornutum and cytotoxicity evaluation of effluents samples by determination of the nucleic acid content (NCA) endpoint. After 60 minutes of ozonation, COD and UV254 only reached 21% and 34% efficiency reduction. Total phenols and color were more rapidly removed (at 10 minutes of treatment). The results showed that the chronic toxicity (Selenastrum capricornutum algae) decreases for all effluent doses studied. The cytotoxicity assay indicated that toxic compounds were not generated by the ozonation process. [ABSTRACT FROM AUTHOR]

We determined the potentially algal-available P (Paa ) 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 Paa given by the dual-culture assay was within a 40% range of that given by the batch approach. The Paa 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 Paa . The analysis of reactive P, which involves direct staining of an unfiltered sample, best approximated the Paa 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. [Copyright &y& Elsevier]

This research is focused on the integrated process for the treatment of bleached Kraft pulp mill effluents. Pre-ozonation of softwood and hardwood combined bleaching effluents at alkaline pH resulted in 50 and 44% COD abatement, respectively. Segregation of highly polluted streams of bleaching process can be recommended to reduce the cost of treatment since the COD removal yield of CEH effluents was higher than combined bleaching effluents. Moreover, biodegradability of CEH effluents in terms of BOD5/COD ratio was increased from 0.16 to 0.32. Noticeable color removal was achieved by pre-ozonation of the CEH stage and combined bleaching effluents. Pre-ozonation enhanced the performance of subsequent algal treatment in the sequential batch reactor (SBR) and activated sludge treatment. Algae have a higher ability to degrade AOX producing compounds together with a high COD removal rate. Although pre-ozonation increased the abatement rate of COD of SBR, the AOX removal rate remained constant as 87%. [ABSTRACT FROM AUTHOR]

Chlorinated phenols and theft derivatives are well known by their high toxicity and may produce negative impact when released to the environment (Fleming 1995). Such compounds are commonly generated during cellulose pulp bleaching, and strict controls should be implemented to limit their discharge into water courses. For instance, the U. S. Environmental Protection Agency, published norms aimed at controlling organochlorine emissions from cellulose pulp bleaching, such as 2-chlorophenol, 2,4-dichlorophenol, 2.4.6.-trichlorophenol, 4- chloro-3-methylphenol, 2,4-dimethylphenol, and other priority pollutants (Federal Register 1998). Effective implementation of such controls implies the use of accurate analytical techniques capable of detecting the presence of such key pollutants in contaminated waters and soils. However, the use of conventional analytical techniques based on spectrometry (UV, visible, IR) and chromatography (GC, TLC, HPLC), for routine detection and quantification of toxic pollutants is limited by high operational costs (Martinez et al. 1996; Scheper T 1992; Scheller and Shubert 1992). On the other hand, biosensors using genetically modified bacteria could be used as a cheaper and simpler alternative (Harayama and Timmis 1992). Such biosensors should contain a reporter gene, e.g., β-galactosidase (lacZ) or luciferase (lux) genes, which operates under transcriptional activator control. The presence of a key contaminant stimulate the transcriptional activator, expressing the reporter gene which, in turn, could be detected by the corresponding enzymatic activity. Thus, under appropriate conditions, a direct correlation between the contaminant concentration and the enzymatic activity could be found (Willardson et al. 1998; Rasmussen et al. 1997). It is interesting to know whether such bio sensors could detect key pollution in real effluents, where complex mixture and toxic effects could impair bacterial activity. In this context, this paper reports experimental results on the capacity of three mutant DmpR strains to detect chlorinated organic compounds present in kraft pulp bleaching effluents. [ABSTRACT FROM AUTHOR]

Thermophilic aerobic treatment of settled pulp and paper mill effluent was studied under mill premises with two comparative pilot processes; suspended carrier biofilm process (SCBP) and activated sludge process (ASP). Full-scale mesophilic activated sludge process was a reference treatment. During the runs (61 days) hydraulic retention times (HRTs) were kept 13 ± 5 h and 16 ± 6 h for SCBP and ASP, respectively. Corresponding volumetric loadings rates (VLR) were 2.7 ± 0.9 and 2.2 ± 1.0 kg CODfilt m-3d-1. Temperatures varied between 46 to 60°C in both processes. Mesophilic ASP was operated with HRT of 36 h, corresponding VLR of 0.7 kg CODfilt m-3d-1. Both SCBP and ASP achieved CODfilt (GF/A filtered) removals up to 85%, while the mesophilic ASP removal was 89 ± 2%. NTU values were markedly higher (100-300) in thermophilic effluents than in mesophilic effluent (30). Effluent turbidity was highly dependent on temperature; in batch experiment mesophilic effluent sample had NTU values of 30 and 60 at 35°C and 55°C, respectively. As a conclusion, both thermophilic treatments gave high CODfilt removals, which were close to mesophilic process removal and were achieved with less than half of HRT. [ABSTRACT FROM AUTHOR]

Colour discharges are gaining renewed focus in the pulp and paper industry as increasingly strict regulatory limits are placed on wastewater quality and aesthetics. In-mill process improvements, such as ECF bleaching and oxygen delignification, have decreased wastewater colour loadings. However, a survey of 12 pulp and paper mill systems found that effluent treatment using aerated stabilisation basins (ASB) leads to average increases in colour of 20-40%. In some instances, this phenomenon may even double the influent colour levels. Activated sludge systems did not produce a colour increase. The measured increases that follow ASB secondary treatment may be sufficient for a mill to fail prescribed discharge standards. A detailed field survey focusing on sections of an integrated bleached kraft mill ASB treatment system was undertaken. The average increase in colour at the final point of discharge was 45%. The major changes in colour concentration occurred in the inlet to the main treatment pond, and in polishing ponds that followed the main treatment pond. Both of these areas receive little or no aeration. No significant change was observed in the highly aerated main pond. These results, along with literature reports, suggested that redox conditions play a major role in influencing colour behaviour. To test this, two series of paired continuously stirred reactors were used to treat whole mill effluent from two ECF bleached kraft mills in parallel. The first series initially treated under anaerobic conditions, followed by an aerobic reactor, while the second series reversed this order. With the initial anaerobic stage, effluent colour increased by 18% and 19% for the first and second series respectively. Subsequent treatment by aerobic bacteria further increased colour by 14% and 6%, for a total increase of 32% and 25%. Initial aerobic treatment, however, did not lead to any significant change in colour for either effluent. Further anaerobic treatment following aerobic conditions produced only small increases in colour. These results are consistent with the ASB and activated sludge system survey, suggesting that anaerobic conditions at the head of treatment systems initiate the observed increases in effluent colour in ASB treatment systems. [ABSTRACT FROM AUTHOR]

The effect of ozone based oxidation on removing recalcitrant organic matter (ROM) and enhancing the biodegradability of alkaline bleach plant effluent was investigated. A bubble column ozonation tower was used in the study. The experiments were carried out at different temperatures (20°C and 60°C) and pH (9 and 11), with a number of biological and chemical parameters being monitored including BOD5, COD, TC, pH, color, and molecular weight distribution of organics (nominal cut off of 1,000 Da). Biodegradability of the effluent was determined based on BOD5/COD of the wastewater throughout the process. For all the experiments, ozonation enhanced the biodegradability of the effluent by 30-40%, which was associated with noticeable removal of ROM including high molecular weight (HMW) and color-causing organics by about 30% and 60%, respectively. While the biodegradability of HMW fraction increased by about 50%, there was no biodegradability improvement for low molecular weight (LMW) portion, which was originally readily biodegradable (with BOD5/COD of about 0.5). Statistical analysis of variance (ANOVA) revealed neither pH nor temperature played significant role on the ozonation process at 95% confidence level. [ABSTRACT FROM AUTHOR]

This work aimed at determining the degree of depuration of a recalcitrant effluent (weak black liquor, WBL) achieved in a series treatment consisting of a first stage methanogenic fluidised bed reactor followed by a second stage aerobic, upflow reactor packed with "biocubes" of Trametes versicolor immobilised onto small cubes of holm oak wood. The mesophilic, lab scale methanogenic fluidised bed reactor contained a microbial consortium immobilised onto granular activated carbon 500 µm average size. The process removed decreasing amounts of organic matter at decreasing hydraulic retention times (HRT), eventually reaching an average of 50% at 0.5 day HRT. Colour and ligninoid removals also decreased with decreasing HRT. Although the methanogenic fluidised bed reactor provided an effective treatment for the degradable organic matter, important concentrations of recalcitrant organic matter and colour still remained in the anaerobic effluent. This anaerobic effluent was fed to the aerobic packed bed reactor. Two HRT were tested in this unit, namely 5 and 2.5 days. The reactor averaged an organic matter removal in the range of 32% COD basis, during an experimental run of 95 days. Colour and ligninoid contents were removed in high percentages (69% and 54%, respectively). There was no significant difference in reactor performance at 5- and 2.5-day HRT. There was a positive correlation between pollutant removal efficiencies and Laccase activity in crude extracts of the reactor liquor. No supplemental soluble carbohydrate was required to sustain the fungus activity and the consistent reactor performance. Overall, the two-stage treatment achieved approximately a 78% removal of the original organic matter of the WBL (COD basis) and ca. 75% of colour and ligninoid contents. [ABSTRACT FROM AUTHOR]

A combination of the suspended carrier biofilm process and the activated sludge process (biofilm-activated sludge -- BAS) has been shown to be very successful for the treatment of different types of pulp and paper mill effluents. The robust biofilm pre-treatment in combination with activated sludge results in a stable, compact and highly efficient process. Recent findings have shown that nutrient limited operation of the biofilm process greatly improves the sludge characteristics in the following activated sludge stage, while minimising sludge production and effluent discharge of nutrients. The nutrient limited BAS process was implemented at full scale at the Södra Cell Värö kraft mill and taken into operation in July 2002. After start-up and optimisation over about 5 months, the process meets all effluent discharge limits. The removal of COD is close to 70% and the removal of EDTA greater than 90%. Typical effluent concentrations of suspended solids and nutrients during stable operations have been 20-30 mg/L TSS, 0.3-0.5 mg/L phosphorus and 3-5 mg/L nitrogen. The sludge production was 0.09 kgSS/kg COD removed and the sludge volume index was 50-100 mL/g. [ABSTRACT FROM AUTHOR]

Parallel laboratory investigations were conducted to examine aspects of two distinct but related bioprocess strategies for low sludge production in the treatment of the same TCF kraft pulp mill effluent. The purpose of this article has been to compare the performance results from these two bench-scale trials with respect to nutrient demands, nutrient discharge, COD removal, and waste sludge characteristics. The LSP (Low Sludge Production) process can be used to significantly reduce sludge yield with excellent sludge characteristics. These sludge characteristics seemed to be related to elevated protozoan grazing pressures. The BAS (Biofilm-Activated Sludge) process achieves similar reduced sludge yields and sludge characteristics while at the same time significantly reducing the nutrient demands and discharge levels. For both LSP and BAS process optimization, the selector nutrient loading is critical to the overall process performance. Selector nutrient requirements are distinct from the overall process nutrient requirements. [ABSTRACT FROM AUTHOR]

Organic matter balances of an ECF kraft mill fiberline were studied in three different operational conditions of the oxygen delignification stage by implementing mill measurements, collecting routine mill data and combining them in a modified PROCELL steady state model. Dissolved volatile solids was the basic measurement for organic matter in liquid streams. Normal operation of the O2D0EOD1EOPD2 fiberline was described successfully. It was also possible to describe exceptional operating situations in the oxygen delignification stage and their effects on other parts of the production process reasonably well in order to focus studies on aspects requiring further attention. The existence of organic matter lost through complete degradation and volatile organic compounds in unit processes as well as its sensitivity to yield and operational situations is shown. The different perspectives of pulp production and wastewater treatment can be brought closer to each other using the approach in this study. The variation in the fractions discharged to wastewater treatment, although a relatively small share of the overall organic matter balance, will continue to become more important also for pulp production when effluent streams are increasingly turned back to the production line through further closure. Studies like the one presented here, can contribute to the evaluation of this development. [ABSTRACT FROM AUTHOR]