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Molded fiber products are regaining popularity for food service applications due to growing concerns about plastic pollution and environmental sustainability. However, to render molded fiber products water and grease resistant, per- and polyfluoroalkyl substances are usually added. In this work, we have demonstrated that cellulose nanofibrils (CNFs) can play a dual role in molded fiber products, both as a binder and as a grease resistant layer. The objective of this work was to produce paper plates via a thermoforming process by hybridizing conventional bleached Kraft pulp (BKP) with lignocellulosic residues such as wood flour (WF) or thermomechanical pulp, using CNFs as a binder. Different formulations were prepared to screen the paper plate formulations and determine the optimal weight percentage ratio of raw materials based on the mechanical properties (tensile and flexural) of the product. The order in which lignocellulosic fibers were added was investigated prior to the experiments and found to have no impact on the mechanical properties of the paper plates. Replacing 35% of BKP with WF and using 10% CNF as a binder resulted in a 90–130% increase in tensile and flexural properties of the paper plates compared to control paper plates made from BKP. Paper plates laminated with 40 g/m 2 CNF exhibited a good grease barrier (Kit 12), a Cobb value of 36 ± 4 g/m 2 , and tear resistance of 14 ± 4.0 (N/mm), and had a smooth surface confirmed through SEM analysis.

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 3 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.

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.

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). 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. 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. 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. 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. 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.

Bioremediation refers to cost-effective and environment-friendly method for converting the toxic, recalcitrant pollutants into environmentally benign products through the action of various biological treatments. Fungi play a major role in bioremediation owing to their robust morphology and diverse metabolic capacity. The review focuses on different fungal groups from a variety of habitats with their role in bioremediation of different toxic and recalcitrant compounds; persistent organic pollutants, textile dyes, effluents from textile, bleached kraft pulp, leather tanning industries, petroleum, polyaromatic hydrocarbons, pharmaceuticals and personal care products, and pesticides. Bioremediation of toxic organics by fungi is the most sustainable and green route for cleanup of contaminated sites and we discuss the multiple modes employed by fungi for detoxification of different toxic and recalcitrant compounds including prominent fungal enzymes viz., catalases, laccases, peroxidases and cyrochrome P450 monooxygeneses. We have also discussed the recent advances in enzyme engineering and genomics and research being carried out to trace the less understood bioremediation pathways.

Three types of wood pulp feedstocks including bleached softwood kraft, unbleached softwood kraft and old corrugated containers were disk refined to produce cellulose nanofibrils at different fineness levels ranging from 50 to 100%, and the resulting aqueous suspensions of cellulose nanofibrils were spray dried. The spray drying experiments were carried out to examine different processing conditions for the different CNF feedstock types and fines level at various suspension concentrations to produce dry samples with free-flowing powder morphologies. The fineness levels and solids contents of CNF suspensions were set to 80% or more and 1.8% or less, respectively. If the solids content of the CNF solutions was high and the fibrillation level was low, plugging was experienced in the spray head because of the high viscosity of the suspensions, resulting in production of poor-quality powders. In terms of reduction in processing energy, even if the CNF suspension solids content was increased to 1.5 wt.%, the powder quality and the production yields were excellent. It was confirmed that high-quality powder under 20 µm were produced at a 90% fibrillation level of all CNF feedstocks. The resulting dry CNF powders were characterized to determine particle size distributions and morphological properties via a scanning electron microscope and a laser diffraction particle size analyzer. The particle sizes were smaller at higher fibrillation levels and lower solids content of the CNF suspensions. The CNF suspension derived from bleached kraft pulp, the average particle size decreased by 43% and 33% with the lowered solids contents from 1.8 to 1%, and the increased fineness levels from 80 to 100%, respectively.

Pulp and paper mills generate pollutants associated to their effluents depending upon the type of process, type of the wood materials, process technology applied, management practices, internal recirculation of the effluent for recovery, the amount of water used in the industrial process and type of secondary treatment. This study is the first that reports a simultaneous evaluation of the effects of tertiary treatments by fungi (Rhizopus oryzae and Pleurotus sajor caju), by enzyme (laccase) and by an oxidation process (photo-Fenton) on individual phenols (vanillin, guaiacol, phloroglucinol, vanillic acid and syringic acid) of a Eucalyptus globulus bleached kraft pulp and paper mill final effluent after secondary treatment (BKPME). The tertiary treatments were applied on BKPME samples and in BKPME samples supplemented with extra concentration of each phenol. Tertiary treatments by Rhizopus oryzae and photoFenton oxidation were able of complete removal (100%) of phenols on BKPME samples whereas P. sajor caju and laccase were able of 60–85% removal. On BKPME samples with added concentration of each phenol, photo-Fenton was the only treatment capable of total phenols removal (100%), which suggests a great potential for its application.

Efficient production of cellulose nanofibers (CNFs) from wood pulp remains a challenge for industrial applications, requiring optimized pretreatment and processing strategies. In this study, hardwood kraft pulp (Hw-BKP) was pretreated with NaOH solutions (5 to 20 wt%) and subsequently processed using a large-scale wet grinder. The effects of pretreatment concentration and grinding on nanofibrillation efficiency were evaluated through compositional, structural, and optical analyses. Alkali pretreatment promoted hemicellulose removal and crystalline transforma-tion, while mechanical grinding facilitated progressive microfibrillation. Notably, pretreatment at concentrations above 15 wt% significantly enhanced nanofibrillation efficiency, highlighting the importance of crystalline transformation in addition to hemicellulose removal. These findings provide practical insights for optimizing CNF production processes and advancing their industrial-scale commercialization.

Production of nanocellulosic materials from loblolly pine (Pinus taeda) kraft pulp provides an opportunity to diversify the portfolio of traditional pulp and paper industries. In this study, pinewood was first subjected to dilute acid pre-extraction with 0.5% sulfuric acid in order to fractionate the hemicellulose, followed by kraft pulping and elemental chlorine free bleaching in order to obtain up to 97% pure cellulose fractions. CNCs (cellulose nanocrystals) were prepared by hydrolyzing the bleached kraft pulp with 64% sulfuric acid at 45 °C for 30 min; the resultant unhydrolyzed solid residues were homogenized using a microfluidizer in order to produce cellulose nanofibers (CNFs). The dilute acid pre-extraction step resulted in complete hydrolysis of galactan and arabinan from pinewood, as well as in partial removal of mannan (80%) and xylan (58%). As a result of pre-extraction, the CNC yield and crystallinity improved by 44% and 11%, respectively, from the corresponding kraft pulps. CNCs produced from the pre-extracted materials also exhibited 16% reduction in particle size, but a 70% increase in sulfur content as well as 20% increase in zeta potential. Higher purity of kraft pulps resulted in higher exposure of cellulose crystalline domains to sulfuric acid thereby resulting in the observed changes. Thus, pulp purity was found to play a significant role in determining the quantity and quality of nanocellulosic materials derived from loblolly pine.

The effect of the fibrillation process through a twin-screw extruder (TSE) on properties of pulp fibers was studied, considering the degree of both fibrillation and degradation of the fibers. Never-dried refined bleached kraft pulp (NBKP) was passed through a TSE several times at a high concentration of 28 wt%. The output of fibrillated fibers had a solid content up to ca. 50 wt%, and the material was in powder form. Characterizations of the morphology, dewatering speed, sedimentation, laser light scattering, scanning electron microscopy of cellulose suspensions, and light transmittance of resin-impregnated films showed that the fibrillation degree of the pulp was enhanced with a higher number of passes. However, the results from thermogravimetry, intrinsic viscosity, and X-ray diffraction analyses indicated that some degradation occurred during the fibrillation process in the TSE. In addition, the mechanical properties of the fibrillated pulp sheets reflected the effects of treatment on the fibrillation and degradation of the cellulose. For never-dried refined NBKP pulp, the best compromise in terms of fibrillation and degradation degree is between 3 and 14 passes, depending on the envisaged properties and applications. The possibility of nanocellulose production at the reported high solid contents is of great interest for industry.