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The efficient removal of emerging pollutant from water is the ultimate frontiers of advanced oxidation processes (AOPs), yet it is challenging to obtain higher catalytic activity and oxidation rate. Herein, a sustainable solution was proposed by optimizing the curvature of confined structure to modulate the electronic state of the active sites in nanochannels for improving the catalytic activity. In addition, the confined effect can enhance the oxidation rate by shorting the mass transfer of active species and pollutants. A void-nanoconfined nanoreactor was prepared by loading Fe 2 O 3 into the nanochannels (<5 nm) of the hollow carbon sphere. An enhancement of 3 orders of magnitude was obtained in the degradation rate constant of void-nanoconfined catalytic system toward sulfamethoxazole (SMX) (6.25 min -1 ) compared with the non-confined system. The kinetics enhancement was attributed to the larger electron potential difference between the outer and inner nanochannel caused by the curvature increase of carbon sphere, accelerating the electron transfer, so that the energy barrier of SMX degradation reaction was reduced by 31 kcal/mol with the assistance of confinement energy. Importantly, the NC-IN/PDS system exhibited outstanding removal efficiency for the actual river water using a continuous flow reactor. This work provides a new insight into designing an efficient and stable catalytic nanoreactor, enriching the domain of advanced wastewater treatment strategies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

This paper explores a novel lifelong learning method with Shared and Private Latent Representations (SPLR), which are learned through synaptic intelligence. To solve a sequence of tasks, by considering the entire parameter learning trajectory, SPLR can learn task-invariant representation which changes little, and task-specific features that change greatly along the entire parameter updating trajectory. Therefore, in the lifelong learning scenarios, our model can obtain a task-invariant structure shared by all tasks and also contain some private properties that are task-specific to each task. To reduce the parameter quantity, a ℓ 1 regularization to promote sparsity is employed in the weights. We use multiple datasets under lifelong learning scenes to verify our SPLR, on these datasets it can get comparable performance compared with existing lifelong learning approaches, and learn a sparse network which means fewer parameters while requiring less model training time., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Modifying natural polymers with silicones gives new possibilities for packaging products and waste management. In this study, the innovative papers produced were altered following the reaction of polysaccharides and organosilicon compounds. The susceptibility of the studied material to biodegradation caused by a brown-rot fungus was assessed. Strength properties by tensile strength and dynamic mechanical analysis and hydrophobic properties by water uptake test and water contact angle analysis were evaluated. Moreover, elemental analysis by ICP method was controlled. The durability against fungi and the hydrophobic properties were increased by the modification. The fungal decay resistance of the silanized paper was reduced by water storage, which allows for managing paper waste. Cellulose-based paper treated with starch-modified methyltrimethoxysilane showed potential as a packaging material due to its reduced water uptake. Possible application areas could be corrugated boxes, cellulose thermoformed products for electronics, and food packaging. However, the water-repellent effect is limited to short-term exposure in humid conditions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Solar-driven interfacial evaporation has enormous promise for fresh water recovery and salt harvesting, but salt accumulation-related challenges stand in its way. Herein, we report a spined groove-ridge pairs inspired by the shell ornamentation of the Vasticardium vertebratum, which addresses salt accumulation by artfully integrating salt reflux into localized salt crystallization. The seashell-mimetic radial V-groove array enables the 3D evaporator to transport water rapidly and directionally, resulting in high-performance water evaporation (∼95% efficiency) and localized crystallization. The periodic spines enlightened by the spine-bearing ridge on the seashell provide considerable micro-unit salt reflux. The 2-in-1 integration design endows the three-dimensional evaporator with superior solar-driven zero liquid discharge and excellent long-term salt resistance even when dealing with high-salinity brine (20 wt% NaCl) and a series of heavy metallic salt solutions. Our design offers a new alternative solution to avoiding salt scaling and could advance locally crystallized solar evaporators towards practical applications., Competing Interests: Declaration of Competing Interest The authors declare no competing interest., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Over 64 billion paper-plastic laminate (PPL) coffee cups are consumed between the United States and Canada annually, the majority accumulating in landfills due to a hydrophobic plastic inner-lining. Recycling can mitigate environmental damage and provide economic value from repurposed products. We found that standard repulping methods were insufficient to separate fiber from plastic due to the low intensity of treatment. To increase process intensity, we mechanically refined shredded PPL coffee cups and Kraft eucalyptus sheets (control) at 2%, 3%, and 4% consistencies with three passes to determine the energy required to separate fibers from plastic and the effects on fiber quality. 2% and 3% consistency PPL cups measured under 40 kWh/tonne of input material for one refiner pass and ∼ 80 kWh/tonne for 4% consistency PPL cups. Recovered fiber fraction totaled 87.7%, 85.3%, and 80.5% of input mass of Kraft eucalyptus and 72.3%, 72.6%, and 79.6% of input mass of PPL cups at 2%, 3%, and 4% consistency, respectively. Fines content of PPL cups jumped from 8% pre-refining to ∼ 30% post-refining while Kraft eucalyptus fibers were unaffected, suggesting that breaking the plastic-fiber bonds results in fines generation. Mean fiber length of PPL cups slightly decreased with consistency and tensile strength improved. Freeness decreased with consistency only in PPL cup samples. These results demonstrate a low energy requirement to effectively separate fiber and plastics in PPL cups as well as minimal impact on fiber quality using existing refining technology, and provides an estimate of the financial costs of local recycling efforts., (Copyright © 2021. Published by Elsevier Ltd.)

Paper mill sludge (PMS) raises critical environmental issues due to its disposal problem, but its high sugar content and well-dispersed structure make it a great feedstock for biochemical production. The technical feasibility of integrating cellulase enzyme production into lactic acid (LA) fermentation from PMS was investigated in this study. The low ash content of PMS suggests a great potential for cellulase production. The enzyme produced using PMS without any treatment gave an activity of 7.8 FPU/ml, a performance comparable to the commercial enzyme, Cellic CTec 2. The LA yield from PMS with in-house enzyme was 64.7% and 73.7% at the enzyme loading of 10 and 15 FPU/g-glucan, respectively. The LA obtained was optically pure L- isomer with over 99% purity. The optimal condition of LA production by Bacillus coagulans was found to be 50 °C and pH 5.3 (with 50 g/L CaCO 3 ). The nutrient effect of yeast extract (YE) and corn steep liquor (CSL) was substrate dependent, and CSL could substitute YE as an inexpensive nutrient when using PMS as a substrate., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Oxygen blown high-temperature gasification constitutes an opportunity for chemical recycling of plastic wastes. This article summarizes the results from comparative tests of combustion and gasification of two complex plastic wastes: a plastic reject (PR) from processing recycled paper and an automotive shredder residue (ASR). Calculated gasification efficiencies corresponded to about 80% and 60%, respectively. Gasification resulted in lower yields of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) compared to direct combustion. A two-stage process, including gasification followed by syngas combustion, reduced the emissions of HCl and PCDD/F in the flue gas to <1.4% and <0.2%, respectively, compared to the levels from direct combustion of the PR feedstock. Most of the PCDD/F (>99%) was captured along with particulate matter (soot) during gasification. The contribution to the toxic concentration of PCDD/F was mainly from the PCDF congeners. Fly ash particulate matter from ASR combustion contained a significant proportion of zinc, which thus constitutes a great potential for use in zinc recycling., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Humic acid (HA) in compost has received widespread attention for its high redox activity, which can mediate the degradation of organic pollution and the passivation of heavy metals in the environment. Hyperthermophilic composting (HTC) can accelerate HA formation. However, few studies have examined whether and how the structures of different organics affect the formation of the HA and HA redox structure at the molecular level in HTC. Detailed molecular information and the redox capacity (electron transfer capacity, ETC) of HA in HTC and thermophilic composting (TC) were characterized using pyrolysis gas chromatography/mass spectrometry and the electrochemical method, respectively. HTC promoted the formation of redox structure, leading to the improvement of the ETC of HA. Aromatics and N-containing compounds were mainly derived from protein components, and the rate at which they were transferred into HA was accelerated in HTC, while the relative abundance of lipids decreased. Partial least squares regression and correlation analysis demonstrated that protein-derived compounds were the key factor determining the HA redox capacity. Finally, partial least squares path modeling suggested that the influence mechanism of protein-derived structures on HA redox capacity might differ in HTC and TC. HTC may promote the relative abundance of N-containing components into the C-skeleton and accelerate the accumulation of the aromatic products, thereby improve the HA redox capacity. These findings provided new insight into how the redox capacity of the HA in compost could be improved and how compost products could be prepared for use in environmental remediation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Pharmaceuticals and personal care products (PPCPs), an emerging class of highly recalcitrant water contaminants, have raised considerable concerns in environment community. Graphitic carbon nitride (CN) has shown a great potential towards the photodegradation of water contaminants under visible light irradiation. However, the conventional bulk CN (BCN) presents the amorphous structure, resulting in an inefficient yield of hydroxyl radicals (•OH) for the complete mineralization of PPCPs. This study provides fundamental insights into significantly enhancing the hydroxyl radical generation via improving the crystallinity of the pristine CN materials. Experimental measurements and accompanying density functional theory (DFT) computational analysis suggest that the crystalline carbon nitride (CCN) exhibited an enhanced adsorption ability towards the dissolved O 2. Upon the light irradiation, the adsorbed O 2 molecules readily undergo a direct two-electron reduction reaction on the CCN surface, instead of the conventional two successive single-electron reduction reactions on the BCN surface, to produce H 2 O 2 subsequently converting into •OH radicals. Along with the improved charge separation efficiency and electron transfer ability, CCN-based materials show superior photocatalytic activity towards PPCPs-type pollutants, compared with the pristine BCN catalysts. Importantly, the catalyst show excellent photodegradation activities under natural sunlight irradiation, at low PPCPs concentration (20 μg/L), in the mixed PPCPs solution or in the real wastewater/water samples, indicating the potential of CCN to enable practical ex situ destructive treatment of PPCPs-contaminated groundwater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Catalytic conversion of xylose and the hemicellulose fraction of waste biomass to furfural is important for the valorization of waste lignocellulose. Here, a clean and efficient catalytic system consisting of sulfonated carbon microspheres catalysts and γ-valerolactone was developed for the upgrading of xylose and waste lignocellulose to the furfural in one-pot. Sulfonated carbon microspheres (CCoS) with Brønsted and Lewis acid sites were prepared to yield furfural. The mesoporous structures were facilitated by introduction of Co element in xylose hydrothermal process, and the density of Brønsted acid sites were improved by the sulfonation. The furfural yield from xylose reached 75.12% using CCoS as catalyst at 170 °C for 30 min in a γ-valerolactone/water (17/3 v/v) solvent. As typical Brønsted acid, the SO 3 H groups on the surface of CCoS catalyst is essential for catalytic dehydration xylose to furfural. Additionally, the mesoporous structures of CCoS improved the mass transfer in the furfural production process. The catalytic system was applied in the conversion of real biomass (including corncob, corn straw and Eucalyptus sawdust) to evaluate the possibility of application. These three biomass species all reached excellent furfural yields, which were more than 70%. This work provided a catalytic strategy for effective conversion of xylose and biomass to furfural., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This study investigated the applicability of parallel factor analysis (PARAFAC) of fluorescence excitation-emission matrices (EEM) spectra to assess the formation potentials (FP) of carbonaceous and nitrogenous disinfection byproducts (C-DBP and N-DBP) and the FP reduction by the magnetic ion exchange resins, MIEX® DOC and MIEX® GOLD. Two source waters of different nature - a surface water and a secondary treated wastewater effluent - were studied. The samples were analyzed for formation potentials of trihalomethanes (THM 4 ), haloacetonitriles (HAN 4 ), haloketones (HK 2 ), and chloropicrin (CPN). A 4-component PARAFAC model was developed from 150 EEM samples generated from the raw source waters and their treatment with MIEX® resins. Components C1, C2, and C3 corresponded to humic-like dissolved organic matter (DOM) while C4 corresponded to protein-like DOM. Both MIEX® resins preferentially removed components C1, C2, and C3 over C4, indicating affinity with humic materials. MIEX® resins were shown to be more effective to treat surface water than secondary effluent, including effective removal of DBP precursors with extended bed volume treatment. Among all parameters investigated, THM 4 -FP strongly correlated with humic-like component C3, while HAN 4 -FP strongly correlated with protein-like component C4 (ρ > 0.89 and p < 0.01); CPN-FP and HK 2 -FP both correlated with anthropogenic DOM C2 (ρ > 0.89 and p < 0.01). Our results indicate that EEM-PARAFAC was valuable for assessing DBP formation potentials and removal of their precursors by MIEX® resins in different water sources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A challenge of today's industry is to transform low-value side products into more value-added materials. The acid-catalyzed conversion of hemi(cellulose) to platform chemicals in green chemical/fuel production and biorefinery yields large formation of insoluble byproduct called humin. Herein, humin obtained from dehydration of glucose was transformed into a novel class of effective carbonaceous solid acid catalyst for the first time via low-temperature pyrolysis followed by sulfonation. A range of preparation conditions were investigated, and the structure-function relationships of the resulting catalysts were also discussed based on the analysis of structure and composition. Comparing with the glucose-derived carbon catalyst, the humin-derived catalyst has substantially larger surface area and higher SO 3 H density, which enable it to display higher catalytic activity and efficiency not only in esterification of levulinic acid and n-butanol (yield = 95.0%, 373 K), but also in hydroxyalkylation/alkylation of 2-methylfuran and furfural (yield = 64.2%, 323 K). Additionally, the catalyst could be repeatedly employed for at least four cycles without obvious deactivation, exhibiting good reusability. This work provides a green method to convert humin byproduct into economic and eco-friendly solid acid catalyst and may contribute to a holistic approach for biomass utilization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Application of thermophilic composting (TC) is limited due to poor efficiency and long composting period. Hyperthermophilic composting (HTC) could effectively overcome this defect. Here, the transformation of humic acid (HA) in both HTC and TC was characterized and compared to investigate the roles of HTC toward accelerating the formation of HA. In HTC, the highest temperature was 96.6 °C, and the hyperthermophilic and thermophilic phases exceed 18 days. The degree of polymerization (DP) in HTC increased to 1.27 on day 27, while it only increased to 1.15 at the end of TC. The elemental composition of the HA in HTC showed higher O atomic content (36.3%) and lower C/N atomic ratio (6.5) compared with TC. These changes indicated that HTC could significantly accelerate oxidized and polycondensed reactions for HA formation, which resulted in the shortening of composting period to 27 days. The maximum fluorescence intensity (F max ) of humic-like components were achieved faster in HTC (F max  = 1649.9) than in TC (F max  = 1316.9), implying that HTC promoted the polycondensation of small molecular components to form HA with larger molecular weight and higher degree of aromatization. Two-dimensional FTIR correlation spectroscopy (2D-FTIR-COS) analysis demonstrated that HTC prevented the HA precursor from condensing before it was deeply oxidized, and increased the content of small molecules rich in carboxyl moieties. Based on the evolution of the molecular structure of HA, the level of oxidation of HA precursors was a key factor to determine the degree of polymerization and the degree of HA humification., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Nanocellulose has achieved an inimitable place and value in nano-materials research sector. Promising and exclusive physical, chemical and biological properties of nanocellulose make it an attractive and ideal material for various high end-user applications. Conventionally, the base material for nanocellulose i.e. cellulose is being extracted from various lignocellulosic raw materials (like wood, agro-industrial-residues, etc.) using pulping followed by bleaching sequences. As an alternate to lignocellulosic raw materials, waste paper also showed potential as a competent raw material due to its abundant availability and high cellulosic content (60-70%) with comparatively less hemicelluloses (10-20%) and lignin (5-10%) without any harsh treatments. The production yields of nanocellulose were reported to vary from 1.5% to 64% depending upon the waste papers and treatments given. The diameters of these nanocelluloses were reported in the range of 2-100 nm and crystallinity range around 54-95%. Thermal degradation of waste paper nanocellulose was varied from 187 °C to 371 °C. Although these properties are comparable with the nanocellulose obtained from lignocellulosic raw materials, yet waste paper is an underutilized source for nanocellulose preparation due to its ordinary fate of recycling, dumping and incineration. In the sight of necessity and possibility of waste paper utilization, this article reviews the outcomes of research carried out for preparation of nanocellulose using waste paper as a source of cellulose. There is a need of sincere investigation to convert this valuable waste to wealth i.e. waste papers to nanocellulose, which will be helpful in solid waste management to protect environment in economical way., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Waste biomass derived heterogeneous catalyst is an excellent alternative to chemically synthesized catalysts. In this work, calcined Tectona grandis leaves were proposed as an eco-friendly, renewable and low cost heterogeneous base catalyst. The prepared catalyst was examined by FTIR, XRD, XPS, SEM, EDX, TEM, TGA, BET and Hammett indicator test. The catalyst has an appealing nature towards various chemical transformations due to its basic surface sites provided by alkali and alkaline earth metals. The efficiency of the catalyst was successfully investigated by its application in biodiesel production. The products were confirmed by 1 H and 13 C NMR. 100% FAME conversion was attained using a catalyst loading of 2.5 wt% under optimized reaction parameters. The catalyst was further explored for Knoevenagel condensation reaction, in which it showed its effectiveness and recyclability towards the formation of benzylidenemalononitrile derivatives of aryl aldehydes. Thus, it is a potential 'green catalyst' derived from waste biomass without any addition of chemicals that can replace the industrial base catalysts used for biodiesel production and Knoevenagel reaction and makes the protocol environmentally benign., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Each year millions of tons of agricultural wastes are produced, however, not well utilized in China. Considering the economic development and environmental protection, the valorization of these wastes is increasingly necessary and important. Here we used p-toluenesulfonic acid hydrolysis followed by mild disk grinding for on-farm valorization of wheat straw (WS) and their pulping solid residue (waste wheat straw, WWS) to produce lignocellulosic nanofibrils (LCNF). Alkaline peroxide post-treatment was further conducted to obtain purified lignocellulosic nanofibrils (P-LCNF) with lower lignin content and thinner diameters. The raw materials and resulting LCNF and P-LCNF were investigated in each process for their chemical component, crystal structure, morphology, and thermal properties. Interestingly, although WS fiber had higher lignin content than WWS fiber, the WS fiber with lower ash content resulted in LCNF and P-LCNF with smaller height and lower thermal stability, but higher crystallinity and higher specific surface area. Higher ash content in WWS fiber protected cellulose and lignin from depolymerization and degradation, respectively, which endowed LCNF and P-LCNF with entangled network structure. Overall, this study indicated that the low-temperature fractionation process on WS and WWS fibers could yield cellulose nanomaterials with potential value-added application and achieve the efficient utilization of agricultural wastes., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Biochar was produced from anaerobically digested dairy manure under different processing temperatures (300, 600 and 1000 °C). The process could transform the biomass waste to high-value-added biochar products in high efficiency as well as reduce the manure biological pollution to the environment. By the results of thermogravimetric analysis (TGA) two kinetic models (FWO and Starink) were used to evaluate the activation energy. The biochar was studied for its surface area and pore size, chemical functionality, and crystalline structure by BET analysis, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). More porous and channel structures were observed under higher temperature and inert gas atmosphere, as characterized by scanning electron microscopy (SEM). The biochar with tunable physicochemical properties that was produced under different temperatures may be used for soil amendment or other fields., (Copyright © 2018. Published by Elsevier Ltd.)

Reducing brain temperature by head and neck cooling is likely to be the protective treatment for humans when subjects to sudden cardiac arrest. This study develops the experimental validation model and finite element modeling (FEM) to study the head and neck cooling separately, which can induce therapeutic hypothermia focused on the brain. Anatomically accurate geometries based on CT images of the skull and carotid artery are utilized to find the 3D geometry for FEM to analyze the temperature distributions and 3D-printing to build the physical model for experiment. The results show that FEM predicted and experimentally measured temperatures have good agreement, which can be used to predict the temporal and spatial temperature distributions of the tissue and blood during the head and neck cooling process. Effects of boundary condition, perfusion, blood flow rate, and size of cooling area are studied. For head cooling, the cooling penetration depth is greatly depending on the blood perfusion in the brain. In the normal blood flow condition, the neck internal carotid artery temperature is decreased only by about 0.13°C after 60min of hypothermia. In an ischemic (low blood flow rate) condition, such temperature can be decreased by about 1.0°C. In conclusion, decreasing the blood perfusion and metabolic reduction factor could be more beneficial to cool the core zone. The results also suggest that more SBC researches should be explored, such as the optimization of simulation and experimental models, and to perform the experiment on human subjects., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A radiotracer investigation was carried out in an activated sludge process (ASP) system of an effluent treatment plant in a pulp and paper industry. The system consists of an aeration tank and a secondary clarifier connected in series. The primary objective of the investigation was to measure mean hydraulic retention times (MHRTs) of wastewater and investigate the hydraulic performance of the ASP. Residence time distributions (RTD) of the wastewater were measured in an aeration tank and a secondary clarifier of the system using Iodine-131 as a radiotracer. The measured RTD data was treated and MHRTs were estimated. No bypassing was found to exist in the aeration tank and the secondary clarifier. However, the dead volume in the aeration tank and the secondary clarifier was found and estimated to be 2.34% and 4.6%, respectively. The treated curves were further simulated using suitable hydraulically representative mathematical models and detailed flow patterns in the aeration tank and the secondary clarifier were deciphered., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In this study, Fe 0 and mixed anaerobic culture were integrated in one column to investigate the coupled abiotic and biotic effects on hexa-valent chromium (Cr(VI)) removal and column longevity with an abiotic Fe 0 column in the control experiments. According to the breakthrough study, a slower Cr(VI) breakthrough rate of 0.19 cm/PV was observed in the biotic Fe 0 column whereas the value in the abiotic Fe 0 column was 0.30 cm/PV, resulting in 64% longer life-span and 62% higher Cr(VI) removal capacity in the biotic Fe 0 column than the abiotic one. The solid phase characterization by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) confirmed that this enhancement was attributed to the higher consumption of iron and greater production of diverse reactive minerals (e.g., green rust, magnetite and lepidocrocite) induced by the synergistic interaction of Fe 0 and anaerobic culture, providing more reactive sites for Cr(VI) adsorption, reduction and co-precipitation. Furthermore, the decreasing breakthrough rates and growing iron corrosion along the biotic Fe 0 column demonstrated an inhomogeneous distribution of reactive zones in the column and its latter 3/5 section was considered to be the most reactive area for Cr(VI) removal. These results indicate that the inoculation of microorganisms in Fe 0 -based permeable reactive barriers will enable this technology a higher removal capacity and longer life-span for the remediation of Cr(VI)-contaminated groundwater., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

With the introduction of nano zero valent iron (nZVI) technology into our environment, its potential environmental risk to environmental microorganisms has attracted considerable attention. In this study, Pseudomonas putida was chosen as a typical strain to study the bacterial toxicity of nZVI/Pd. The CFU assay results indicated that nZVI/Pd was toxic to P. putida cells but the toxicity decreased with an increase in DO. The experiments isolated by dialysis bag and flow cytometry analysis suggested that both membrane disruption caused by direct contact and oxidative stress were the main bactericidal mechanisms under the aerobic condition, while membrane disruption resulting from direct contact was the primary bactericidal mechanism in the anaerobic system. Furthermore, according to TEM, SEM, EDS, XRD, FTIR and XPS, it was indicated that in the aerobic system, the reactive oxygen species (ROS) generated by nZVI/Pd could oxidize the amide and hydroxyl groups into carboxyl groups, resulting in a decline in peptides and increase in polysaccharides. In addition, the ROS also accumulated inside the cell and caused cell inactivation via oxidative stress. In the anaerobic system, the adhered nZVI/Pd particles would attack the functional groups such as carboxyl, ester and amide, leading to the decline in proteins and polysaccharides and subsequent damage of the membrane. The findings provide a significant guide for the application of nano-bio combined technology., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Pulp and paper mills are indispensable for any nation as far as the growth of the nation is concerned. Due to fast growth in population, urbanization and industrialization, the demand and consumption of paper has increased tremendously. These put high load on our natural resources and force the industry to look for alternative raw material. Rice straw is a lignocellulosic material abundantly available in wood short countries like China, India, Bangladesh, etc. and can be used as raw material for this industry. Open burning of rice straw releases noxious green house gases to the air and poses serious threats to global air chemistry and human health. So, it is a dual benefit option (for farmers and industries) to use rice straw as a raw material in pulp and paper industry. Organosolv pulping using acids are the prominent choices of researchers to convert this residue into valuable pulp but in developed countries only. Developing world favours the soda and soda-AQ processes as these are economical. As a virtue of less lignin content in comparison to wood, rice straw requires less harsh conditions for cooking and can be easily pulped. Bleaching is a crucial step of paper making but also responsible for causing water pollution. Many studies revealed that during the process more than 500 chlorinated compounds are released that are highly toxic, bioaccumulative and carcinogenic in nature. Most of the industries over the globe switch on to the elemental chlorine free short sequence bleaching methods using chlorine dioxide, hypochlorite and hydrogen peroxide. This paper presented the effective need of ecofriendly, economically reliable pulping and bleaching sequences in case of rice straw to eliminate the problems of chlorinated compounds in wastewater of paper mills. Such approach of using waste as a raw material with its environmentally safe processing for making paper can prove to be valuable towards sustainable growth., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Sewage fine sieved fraction (FSF) is a heterogeneous substrate consisting of mainly toilet paper fibers sequestered from municipal raw sewage by a fine screen. In earlier studies, a maximum biodegradation of 62% and 57% of the sewage FSF was found under thermophilic (55°C) and mesophilic (35°C) conditions, respectively. In order to research this limited biodegradability of sewage FSF, this study investigates the biodegradation of different types of cellulosic fibers-based hygiene papers including virgin fibers based toilet paper (VTP), recycled fiber based toilet paper (RTP), virgin pulp for paper production (VPPP) as a raw material, as well as microcrystalline cellulose (MCC) as a kind of fiberless reference material. The anaerobic biodegradation or digestibility tests were conducted under thermophilic and mesophilic conditions. Results of the experiments showed different biomethane potential (BMP) values for each tested cellulose fiber-based substrate, which might be associated with the physical characteristics of the fibers, type of pulping, presence of lignin encrusted fibers, and/or the presence of additive chemicals and refractory compounds. Higher hydrolysis rates (Kh), higher specific methane production rates (SMPR) and shorter required incubation times to achieve 90% of the BMP (t90%CH4), were achieved under thermophilic conditions for all examined substrates compared to the mesophilic ones. Furthermore, the biodegradability of all employed cellulose fiber-based substrates was in the same range, 38-45%, under both conditions and less than the observed FSF biodegradability, i.e. 57-62%. MCC achieved the highest BMP and biodegradability, 86-91%, among all cellulosic substrates., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

For paper and paperboard packaging, recyclability plays an important role in conserving the resources and reducing the environmental impacts. Therefore, when it comes to the nano-enabled paper packaging material, the recyclability issue should be properly addressed. This study represents our first report on the fate of nanomaterials in paper recycling process. The packaging material of concern is a PLA (Polylactic Acid) coated paper incorporating zinc oxide nanoparticles in the coating layer. The material was characterised and assessed in a lab-scale paper recycling line. The recyclability test was based on a method adapted from ATICELCA MC501-13, which enabled to recover over 99% of the solids material. The mass balance result indicates that 86-91% zinc oxide nanoparticles ended up in the rejected material stream, mostly embedded within the polymer coating; whereas 7-16% nanoparticles ended up in the accepted material stream. Besides, the tensile strength of the recycled handsheets suggests that the nano-enabled coating had no negative impacts on the recovered fibre quality., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The morphological properties of cellulose nanofibrils obtained from eucalyptus pulp fibres were assessed. Two samples were produced with the same chemical treatment (NaClO/NaBr/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation), but distinct mechanical treatment intensities during homogenization. It was shown that the nanofibrils production yield increases with the mechanical energy. The effect of mechanical treatment on the yield was confirmed by laser profilometry of air-dried nanocellulose films. However, no significant differences were detected regarding the nanofibrils width as measured by atomic force microscopy (AFM) of air-dried films. On the other hand, differences in size were found either by laser diffraction spectroscopy or by dynamic light scattering (DLS) of the cellulose nanofibrils suspensions as a consequence of the differences in the length distribution of both samples. The nanofibrils length of the more nanofibrillated sample was calculated based on the width measured by AFM and the hydrodynamic diameter obtained by DLS. A length value of ca. 600 nm was estimated. The DLS hydrodynamic diameter, as an equivalent spherical diameter, was used to estimate the nanofibrils length assuming a cylinder with the same volume and with the diameter (width) assessed by AFM. A simple method is thus proposed to evaluate the cellulose nanofibrils length combining microscopy and light scattering methods., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In the present study, functionalization of mixed office waste (MOW) paper has been carried out to synthesize carboxymethyl cellulose, a most widely used product for various applications. MOW was pulped and deinked prior to carboxymethylation. The deinked pulp yield was 80.62 ± 2.0% with 72.30 ± 1.50% deinkability factor. The deinked pulp was converted to CMC by alkalization followed by etherification using NaOH and ClCH2COONa respectively, in an alcoholic medium. Maximum degree of substitution (DS) (1.07) of prepared CMC was achieved at 50 °C with 0.094 M and 0.108 M concentrations of NaOH and ClCH2COONa respectively for 3h reaction time. The rheological characteristics of 1-3% aqueous solution of optimized CMC product showed the non-Newtonian pseudoplastic behavior. Fourier transform infra red (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscope (SEM) study were used to characterize the CMC product., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The aim of this paper is to analyse the effects of the presence of printed electronics on the paper waste streams and specifically on paper recyclability. The analysis is based on a case study focussed on envelopes for postal and courier services provided with these intelligent systems. The smart printed envelope of the study includes a combination of both conventional (thin flexible batteries and resistors) and printed electronic components (conductive track layout based on nanosilver ink). For this purpose, a comparison between envelopes with and without these components (batteries, resistors and conductive track layouts) was carried out through pilot scale paper recycling tests. The generation of rejects during the recycling process as well as the final quality of the recycled paper (mechanical and optical properties) were tested and quantitatively evaluated. The results show that resistors are retained during the screening process in the sieves and consequently they cannot end up in the final screened pulp. Therefore, mechanical and optical properties of the recycled paper are not affected. Nevertheless, inks from the conductive track layouts and batteries were partially dissolved in the process water. These substances were not totally retained in the sieving systems resulting in slight changes in the optical properties of the final recycled paper (variations are 7.2-7.5% in brightness, 8.5-10.7% in whiteness, 1.2-2.2% in L(∗) values, 3.3-3.5% in opacity and 16.1-27% in yellowness). These variations are not in ranges able to cause problems in current paper recycling processes and restrict the use of recycled paper in current applications. Moreover, real impacts on industrial recycling are expected to be even significantly lower since the proportion of paper product with printed circuits in the current paper waste streams are much lower than the ones tested in this work. However, it should be underlined the fact that this situation may change over the next years due to the future developments in printed electronics and the gradual penetration of these types of devices in the market., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Despite the significant progress on iron reduction by thermophilic microorganisms, studies on their ability to reduce toxic metals are still limited, despite their common co-existence in high temperature environments (up to 70°C). In this study, Methanothermobacter thermautotrophicus , an obligate thermophilic methanogen, was used to reduce hexavalent chromium. Experiments were conducted in a growth medium with H 2 /CO 2 as substrate with various Cr 6+ concentrations (0.2, 0.4, 1, 3, and 5 mM) in the form of potassium dichromate (K 2 Cr 2 O 7 ). Time-course measurements of aqueous Cr 6+ concentrations with the 1, 5-diphenylcarbazide colorimetric method showed complete reduction of the 0.2 and 0.4 mM Cr 6+ solutions by this methanogen. However, much lower reduction extents of 43.6%, 13.0%, and 3.7% were observed at higher Cr 6+ concentrations of 1, 3 and 5 mM, respectively. These lower extents of bioreduction suggest a toxic effect of aqueous Cr 6+ to cells at this concentration range. At these higher Cr 6+ concentrations, methanogenesis was inhibited and cell growth was impaired as evidenced by decreased total cellular protein production and live/dead cell ratio. Likewise, Cr 6+ bioreduction rates decreased with increased initial concentrations of Cr 6+ from 13.3 to1.9 µM h -1 . X-ray absorption near-edge structure (XANES) spectroscopy revealed a progressive reduction of soluble Cr 6+ to insoluble Cr 3+ precipitates, which was confirmed as amorphous chromium hydroxide by X-ray diffraction and selected area electron diffraction pattern. However, a small fraction of reduced Cr occurred as aqueous Cr 3+ . Scanning and transmission electron microscope observations of M. thermautotrophicus cells after Cr 6+ exposure suggest both extra- and intracellular chromium reduction mechanisms. Results of this study demonstrate the ability of M. thermautotrophicus cells to reduce toxic Cr 6+ to less toxic Cr 3+ and its potential application in metal bioremediation, especially at high temperature subsurface radioactive waste disposal sites, where the temperature may reach ∼70°C.

Allergic contact dermatitis can develop following repeated exposure to allergenic substances. To date, hazard identification is still based on animal studies as non-animal alternatives have not yet gained global regulatory acceptance. Several non-animal methods addressing key-steps of the adverse outcome pathway (OECD, 2012) will most likely be needed to fully address this effect. Among the initial cellular events is the activation of keratinocytes and currently only one method, the KeratinoSens™, has been formally validated to address this event. In this study, a further method, the LuSens assay, that uses a human keratinocyte cell line harbouring a reporter gene construct composed of the antioxidant response element (ARE) of the rat NADPH:quinone oxidoreductase 1 gene and the luciferase gene. The assay was validated in house using a selection of 74 substances which included the LLNA performance standards. The predictivity of the LuSens assay for skin sensitization hazard identification was comparable to other non-animal methods, in particular to the KeratinoSens™. When used as part of a testing battery based on the OECD adverse outcome pathway for skin sensitization, a combination of the LuSens assay, the DPRA and a dendritic cell line activation test attained predictivities similar to that of the LLNA., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Phytosterols are plant-derived sterols present in pulp and paper wastewater and have been implicated in the endocrine disruption of aquatic species. Bioassays were performed to assess the effect of an additional carbon source and/or solubilizing agent on the aerobic biotransformation of a mixture of three common phytosterols (β-sitosterol, stigmasterol and campesterol). The aerobic biotransformation of the phytosterol mixture by a mixed culture developed from a pulp and paper wastewater treatment system was examined under three separate conditions: with phytosterols as the sole added carbon source, with phytosterols and dextrin as an additional carbon source, and with phytosterols added with ethanol as an additional carbon source and solubilizing agent. Significant phytosterol removal was not observed in assays set up with phytosterol powder, either with or without an additional carbon source. In contrast, all three phytosterols were aerobically degraded when added as a dissolved solution in ethanol. Thus, under the experimental conditions of this study, the bioavailability of phytosterols was limited without the presence of a solubilizing agent. The total phytosterol removal rate was linear for the first six days before re-spiking, with a rate of 0.47 mg/L-d (R(2) = 0.998). After the second spiking, the total phytosterol removal rate was linear for seven days, with a rate of 0.32 mg/L-d (R(2) = 0.968). Following the 7th day, the phytosterol removal rate markedly accelerated, suggesting two different mechanisms are involved in phytosterol biotransformation, more likely related to the production of enzyme(s) involved in phytosterol degradation, induced under different cell growth conditions. β-sitosterol was preferentially degraded, as compared to stigmasterol and campesterol, although all three phytosterols fell below detection limits by the 24th day of incubation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Nanopaper is a new material concept composed of nanocellulose, which has been proposed for a series of applications. Recently, the surface of nanopapers has also been emphasized as an important structure to control. This is due to the potential of nanopaper structures as a substrate for printing functionality, which could expand the applicability of nanopaper as a functionalized biomaterial. In this study, we demonstrate how the roughness of nanopaper is affected by the fraction of residual fibres that were not fibrillated into nanofibrils after a homogenization procedure. The topography and morphology were assessed with laser profilometry, atomic force microscopy and scanning (transmission) electron microscopy. The results show a linear correlation between the estimated fraction of residual fibres and the roughness of the assessed nanopapers. Furthermore, the fraction of residual fibres can be reduced by fractionating the nanocellulose, which is demonstrated in the present work. Such knowledge will be valuable for designing nanopaper surfaces with specific structural characteristics., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The use of recycled and waste thermoplastics has been recently considered for producing wood plastic composites (WPCs). They have great potential for WPCs manufacturing according to results of some limited researches. This paper presents a detailed review about some essential properties of waste and recycled plastics, important for WPCs production, and of research published on the effect of recycled plastics on the physical and mechanical properties of WPCs., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In this study, the suitability of optical devices for quantification of the fibrillation degree of bleached microfibrillated cellulose (MFC) materials has been assessed. The techniques for optical assessment include optical scanner, UV-vis spectrophotometry, turbidity, quantification of the fiber fraction and a camera system for dynamic measurements. The results show that the assessed optical devices are most adequate for quantification of the light transmittance of bleached MFC materials. Such quantification yields an estimation of the fibrillation degree. Films made of poorly fibrillated materials are opaque, while films made of highly fibrillated materials containing a major fraction of nanofibrils are translucent, with light transmittance larger than 90%. Finally, the concept of using images acquired with a CCD camera system, for estimating the fibrillation degree in dynamic conditions was exemplified. Such systems are most interesting as this will widen the applicability of optical methods for quantification of fibrillation degree online in production lines, which is expected to appear in the years to come., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The complementary capabilities of various characterisation methods for micro-structural assessment are demonstrated. The assessed structures were composed of unbleached microfibrillated cellulose (MFC) in combination with bleached and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) pre-treated MFC materials. The biodegradable nano-composites were thus characterised in detail, including laser profilometry, scanning electron microscopy (SEM) in high and low vacuum modes, and field-emission SEM. The distribution of the unbleached MFC materials was assessed by staining the unbleached MFC with osmium tetroxide (OsO(4)), which reacts with C=C double bonds encountered in lignin. In addition, some properties of the MFC nano-composite films were tested, i.e. tensile properties, water wettability and oxygen permeability. In general, the group of characteristics of the nano-composite MFC films was better than the properties of the films made of the neat MFC qualities. This indicates that mixing complementary MFC qualities could give synergetic effects that are not exploited completely when using the MFC qualities separately. The study thus confirms the suitability of unbleached MFC materials as a component in multilayer structures, for example biodegradable packaging applications., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Novel lightweight composite foams based on recycled polypropylene reinforced with cellulosic fibres obtained from agricultural residues were prepared and characterized. These composites, initially prepared by melt-mixing recycled polypropylene with variable fibre concentrations (10-25 wt.%), were foamed by high-pressure CO(2) dissolution, a clean process which avoids the use of chemical blowing agents. With the aim of studying the influence of the fibre characteristics on the resultant foams, two chemical treatments were applied to the barley straw in order to increase the α-cellulose content of the fibres. The chemical composition, morphology and thermal stability of the fibres and composites were analyzed. Results indicate that fibre chemical treatment and later foaming of the composites resulted in foams with characteristic closed-cell microcellular structures, their specific storage modulus significantly increasing due to the higher stiffness of the fibres. The addition of the fibres also resulted in an increase in the glass transition temperature of PP in both the solid composites and more significantly in the foams., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Wood fibres have been utilized by our society as an important component of paper products and are presently gaining more interest as reinforcement in composite materials. During the last decades biochemical treatments have also found applications in the processing of wood fibres. The chemical, mechanical and biochemical treatments affect the morphology of the fibre wall structure at the micro- and nano-level. In this study, we present a modern approach where field-emission SEM (FE-SEM) and relevant computerized image analysis are applied to quantify the fibre wall characteristics. Details such as surface roughness and texture of the fibre walls are quantified objectively. Global polar plots are generated, which are considered to represent the fingerprint of a given pulp. The approach offers a novel perspective in the characterisation of surface structures, moving forward from performing subjective evaluations to performing objective quantifications of wood pulp fibre surfaces., ((c) 2010 Elsevier Ltd. All rights reserved.)

A shape description approach is introduced as a step for performing an automatic processing of fibre cross-sectional images. The approach, in combination with appropriate mathematical morphology, yields edited images, which are suitable for further computerized image analysis. Important parameters such as fibre wall thickness, fibre perimeter, form factor and collapse index are quantified effectively and objectively. Although some differences are encountered within groups of split fibres, manual and automatic quantification of intact fibres yields similar results. In addition, the suitability of a distance transform approach for quantifying the fibre inter-distances in composites is demonstrated. Such tools will be valuable for understanding the mechanical properties of engineered fibre-reinforced composite materials.

Performance and efficiency of old newspaper (ONP) deinking by combining cellulase/hemicellulase with laccase-violuric acid system (LVS) were investigated in this study. Brightness, effective residual ink concentration (ERIC) and physical properties were evaluated for the deinked pulp. Fiber length, coarseness, specific surface area and specific volume were also tested. The changes of dissolved lignin during the deinking processes were measured with UV spectroscopy. The fiber morphology was observed with environmental scanning electronic microscopy (ESEM). Experimental results showed that, compared to the pulp deinked with each individual enzyme, ERIC was lower for the cellulase/hemicellulase-LVS-deinked pulp. This indicated that a synergy existed in ONP deinking using a combination of enzymes. After being bleached by H(2)O(2), enzyme-combining deinked pulp gave higher brightness and better strength properties. Compared with individual enzyme deinked pulp, average fiber length and coarseness decreased a little for the enzyme-combining deinked pulps. A higher specific surface area and specific volume of the pulp fibers were achieved. UV analysis proved that more lignin was released during the enzyme-combining deinking process. ESEM images showed that more fibrillation was observed on the fiber surface due to synergistic treatment.

Cyclodextrins (CDs) increase the cake solids and drainage rate of belt-pressed biological or primary sludge when added to the sludge slurry along with conventional conditioning chemicals. These benefits are obtained at very low CD dosage. A 2.8 percentage point increase in cake solids was obtained in a full-scale trial with mixed primary and biological sludge from a paper mill. CDs also decrease the specific resistance to filtration and increase the capture rate of solids during belt pressing. Mechanistic studies showed that CDs increase the surface tension of c-PAM polymers in water and reduce the turbidity, indicating that they are able to aggregate the charged polymers, and, by inference, sludge particles treated with the polymer. A mechanism is proposed where CDs reduce excessively charged regions of the polymer-treated surface of the sludge, thereby facilitating its flocculation.

Almost all of the kraft pulp bleach plants worldwide are now practicing elemental chlorine-free (ECF) process to comply with environmental regulations in different countries. Usually, these conventional ECF bleaching sequences contain one or two alkaline extraction stages of which the first one is often the principal source of color and chemical oxygen demand (COD) in the resulting effluent. However, the results of this study showed that the ECF sequences which did not include any alkaline extraction stage and contained solely chlorine dioxide decreased both the color and COD loads of the effluent. On the other hand, the ECF sequences containing both chlorine dioxide and hydrogen peroxide but excluding the alkaline extraction stage could lower only the color but not the COD load. It is suggested that the total kappa factor (the ratio of the total active chlorine to the kappa number) affected the COD load and that the content of hexeneuronic acid groups influenced the color of the bleach effluent. Compared to the reference pulp, the viscosity of the pulp from the exclusively chlorine-dioxide-based ECF sequence without the alkaline extraction stage was lower but the tear index and sheet density at a given tensile index were similar.

Subjecting a suspension of biological sludge to underwater sparks (3kV, 50kA) leads to its consolidation, decreases the charge density on the solids, and increases its settling rate. The cake solids increase, but by only one percentage point. High-speed video images show that the spark generates a steam bubble. The dynamics of bubble growth could be estimated through the Rayleigh model. The bubble collapses into an acoustic field, which then agglomerates the particles. Sparking does not affect the settling rate of an aqueous slurry of softwood pulp because the fibrous particles are too large to be aggregated by an acoustic pulse.

Twelve independent batch experiments (<9h) with fresh municipal activated sludge were conducted to assess the occurrence and the mechanisms of deflocculation under a temperature shift from 30 to 45 degrees C. In each experiment, a transient reactor (2 L) was subjected to the temperature shift and a control reactor was operated at a constant temperature of 30 degrees C. The occurrence of deflocculation was demonstrated by the increase in turbidity and in the concentrations of biopolymers in the sludge supernatant from the transient reactor. The maximum levels of proteins in the supernatants ranged from 53 to 81 mg/L, for DNA from 34 to 36 mg/L, for humic compounds from 20 to 40 mg/L, and for carbohydrates from 21 to 31 mg/L. All the biopolymer concentrations in the control reactor remained below 5-10 mg/L. The release of biopolymers was accompanied by an increase in sludge supernatant conductivity (16-32% increase, up to 1.20 mS/cm), soluble chemical oxygen demand (from 129 to 440 mg/L), total suspended solids (>25 mg/L up to 128 mg/L), and a decrease in the mixed liquor volatile suspended solids (up to 11%). The temperature shift was also found to inhibit microbial metabolism by reducing the sludge biomass substrate removal capacity, as measured by oxygen-uptake rates. The temperature shift had a marginal effect causing sludge lysis (as an increase in beta-galactosidase activity) and had no significant impact on sludge viability (live/dead ratio of bacterial cells). It was concluded that sludge deflocculation under a temperature shift from 30 to 45 degrees C involves the solubilisation of extracellular polymeric substances from the flocs and likely also floc fragmentation. In addition, sludge deflocculation and the inhibition of microbial metabolism explain the poor treatment performance observed in previous continuous reactors under similar temperature shifts.

The effects of temperature variations on aerobic biological wastewater treatment were evaluated with respect to treatment efficiency, solids discharges, sludge physicochemical properties and microbiology. The effects of controlled temperature shifts (from 35 degrees to 45 degrees C; from 45 degrees to 35 degrees C) and periodic temperature oscillations (from 31.5 degrees C to 40 degrees C, 6-day period, for 30 days) were assessed in 4 parallel, lab-scale sequencing batch reactors (SBRs) that treated pulp and paper mill effluent. Overall, the temperature shifts caused higher effluent suspended solids (ESS) levels (25-100 mg/L) and a decrease (up to 20%) in the removal efficiencies of soluble chemical oxygen demand (SCOD). Lower ESS levels were triggered by a slow (2 degrees C/day) versus a fast (10 degrees C/12h) temperature shift from 35 degrees to 45 degrees C, but the SCOD removal efficiencies decreased similarly in both cases (from 66+/-3% and 65+/-2% to 49+/-3% and 51+/-3%). Temperature oscillations caused an increased deterioration of the sludge settleability [high sludge volume indices (SVI); low zone settling velocities (ZSV)], high ESS levels and lower SCOD removals. The temperature transients were associated with poor sludge settleability (SVI>100 mL/g MLSS, ZSV<1 cm/min), more negatively charged sludge (up to -0.35+/-0.03 meq/g MLSS), increased filament abundance (approximately 4 to 4.5, subjective scale equivalent to very common), and decreased concentrations of protozoa and metazoa (25,000-50,000 microorganisms/mL sludge). The controlled, periodic temperature oscillations had a slight impact on SCOD removal efficiency (5% decrease), and did not seem to select for robust microorganisms that withstood the temperature shift. Sludge deflocculation and filament proliferation caused by these temperature transients may explain the higher ESS levels.

The coagulation-anaerobic acidification-aeration package reactor was designed for the treatment of pulp CEH bleaching effluents, the efficiencies in CODcr, BOD(5), AOX and toxicity removal achieved were 88.1%, 81.0%, 98.4% and 92.0%, respectively, with 15 h HRT. The toxicity and AOX were removed mainly through coagulation and anaerobic process, while the COD and BOD(5) were removed mainly through coagulation and aerobic process. The pretreatment of coagulation precipitation decreased the following organic load, which decreased the following treatment retention time and increased the stability of the system. The results of GC-MS showed: pollutants of wastewater were mainly chlorinated organics, most of AOX and the toxicity were removed by reductive dechlorination and acidified hydrolysis in anaerobic unit, the high COD removal in aerobic unit showed further degradation of pollutants. Chlorine atoms in the ortho position were preferentially dechlorination, that in para position were difficult to remove from chlorinated phenols during biological treatment.

Profiles of resin and fatty acids (RFAs), COD, and aquatic toxicity were measured across the secondary treatment systems of three pulp mills. The RFAs sorb to suspended solids, principally fiber, and are partially removed through settling. An activated sludge system is more efficient in removing RFAs than an aerated stabilization basin (ASB) because of its higher solids level. Dehydroabietic acid accounts for a significant fraction of the effluent toxicity in the two ASBs studied. The microorganisms in an ASB are unable to respond rapidly to an RFA spill, and effluent toxicity can be elevated for a prolonged period because of hydraulic backmix. The applicability of several laboratory studies to field situations is assessed.

Co-firing of coal and paper mill sludge was conducted in a 103 MWth circulating fluidized bed boiler to investigate the effect of the sludge feeding rate on emissions of SOx, NOx, and CO. The preliminary results show that emissions of SOx and Nx decrease with increasing sludge feeding rate, but CO shows the reverse tendency due to the decrease in combustion temperature caused by a large amount of moisture in the sludge. All emissions met the local environmental requirements. The combustion ashes could be recycled as feed materials in the cement manufacturing process.

A set of four assays designed to rapidly measure the health and biodegradative performance of pulp and paper mill activated sludges was developed. Three of the assays are specific oxygen uptake rates (SOURs) that measure the normal "working" aeration tank BOD (biochemical oxygen demand) removal rate (SOURAT), a near-maximum BOD removal rate (SOURNMAX), and a rate (SOURTOX) used in combination with the SOURNMAX to indicate the presence of toxic or inhibitory substances. The fourth assay is the specific adenosine triphosphate (SATP) content of the sludge, used as a measure of its viable cell content. Fresh biomass (sludge) samples from one laboratory reactor and four mill biotreatment systems were fed raw mill effluents and used to evaluate the four-assay set. The SOURAT values of all systems were 10-40% of their SOURNMAX values: thus the SOURAT:SOURNMAX ratios indicate that each system's free biodegradative capacity was far greater than its operating rate. It was demonstrated using phenol that the SOURNMAX:SOURTOX ratio can indicate the presence of substances toxic or inhibitory to the biomass. The results also indicated that the SOURNMAX is a much better indicator of improving or worsening sludge performance and capacity than the SOURAT. SATP was shown to be a useful monitor of the proportion of viable cells in an activated sludge and a toxicity indicator complementary to the SOURNMAX:SOURTOX ratio and similar in principle to the commercial Microtox toxicity test. This four-assay set was also applied to three practical situations: (a) at-mill monitoring of a biotreatment system; (b) effects of cold storage on biomass; and (c) effects of decreased BOD loading on biomass.

Coliform bacteria have long been used to indicate fecal contamination of water and thus a health hazard. In this study, the in-mill water and external effluent treatment systems of seven typical Canadian pulp and paper mills were all shown to support the growth of numerous coliforms, especially Klebsiella Spp., Escherichia coli. Enterobacter spp., and Citrobacter spp. In all mills and most sampled locations, klebsiellas were the predominant coliforms. Although all but one of the mills had no sewage input and most disinfected their feed (input) water, all contained the most typical fecal indicator bacterium, E. coli. Many of the mill coliforms were classified as fecal coliforms by standard "MPN" and metabolic tests, but this was shown to be due to their thermotolerance, not their origin. Mill coliforms were shown not to be just simple transients from feedwater or furnish (wood), but to be continuously growing, especially in some of the primary clarifiers. Isolated mill coliforms grew very well on a sterilized raw combined mill effluent. The fecal streptococci (enterococci), alternative indicators of fecal health hazards, were common in all mills in the absence of sewage. Ten strains of E. coli isolated from four mills were all shown to be non-toxigenic strains of harmless serotypes. No salmonellas were found. Therefore, the use of total coliform, fecal coliform, enterococci, or E. coli counts as indicators of fecal contamination, and thus of health hazard in pulp and paper mill effluents or biosolids (sludges) known to be free of fecal input is invalid.

Resin acids are the major toxicants in pulp and paper mill effluents (PPMEs), and they form pitch interfering with papermaking. Efficient and reliable resin acid removal is critically important to prevent toxicity discharge and ensure proper functioning of paper machines. Two resin-acid-degrading bacteria, Pseudomonas abietaniphila BKME-9 and Zoogloea resiniphila DhA-35, were tested in laboratory sequencing batch reactors (SBRs) for their ability to enhance resin acid removal by biomass from a full-scale biotreatment system treating PPMEs. Both bacteria enhanced resin acid removal but not removal of total organic carbon (TOC) by either pH-shocked or starved activated sludge. These two bacteria also increased resin acid removal when the sludge was given high concentration (200 microM) of resin acid. A most-probable-number polymerase chain reaction (MPN-PCR) assay showed that these two bacteria were initially not detectable (detection limit: 10(2) bacterial cells/ml) in the sludge community and were persistent after inoculation. Both bacteria did not substantially change the indigenous microbial community composition, as assayed by ribosomal intergenic spacer analysis (RISA). Our results suggest that it is feasible and potentially useful to enhance resin acid removal by bioaugmentation using resin-acid-degrading bacteria such as BKME-9 and DhA-35.