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Mitigation of global warming, energy security and industrial competitiveness urge the energy-intensive pulp and paper industry (PPI) to transform energy use practices. This study investigates how the PPI has responded to the need for the energy transition in the 2000s. Finland and Sweden as forerunners of energy-efficient operation and decarbonization of the PPI are used as target countries. Understanding of changes in energy consumption is complemented using decomposition analysis (Logarithmic Mean Divisia Index Method) and the energy efficiency index approach. Analysis of companies’ investments in energy technologies is used for explaining changes in energy production. Evidence of significant development towards the more sustainable operation of the PPI was found. Energy consumption per produced unit has decreased, i.e., energy efficiency has improved. Fossil fuels have been partially replaced with bio-based alternatives. Thus, the CO2 intensity has decreased substantially. The generation of renewable electricity has increased in both countries. Examples of Finland and Sweden indicate that the PPI has great potential to contribute to CO2 emission reduction worldwide in the future as energy efficiency can be further improved, and the share of fossil fuels can be decreased increasing the use of biofuels and self-generated green electricity at least in kraft pulp mills.

A wide variety of biomass is available all around the world. Most of the biomass exists as a by-product from manufacturing industries. Pulp and paper mills contribute to a higher amount of these biomasses mostly discarded in the landfills creating an environmental burden. Biomasses from other sources have been used to produce different kinds and grades of biomaterials such as those used in industrial and medical applications. The present review aims to investigate the availability of biomass from pulp and paper mills and show sustainable routes for the production of high value-added biomaterials. The study reveals that using conventional and integrated biorefinery technology the ample variety and quantity of waste generated from pulp and paper mills can be converted into wealth. As per the findings of the current review, it is shown that high-performance carbon fiber and bioplastic can be manufactured from black liquor of pulping waste; the cellulosic waste from sawdust and sludge can be utilized for the synthesis of CNC and regenerated fibers such as viscose rayon and acetate; the mineral-based pulping wastes and fly ash can be used for manufacturing of different kinds of biocomposites. The different biomaterials obtained from the pulp and paper mill biomass can be used for versatile applications including conventional, high performance, and smart materials. Through customization and optimization of the conversion techniques and product manufacturing schemes, a variety of engineering materials can be obtained from pulp and paper mill wastes realizing the current global waste to wealth developmental approach.

Maturity of vermicomposted end products obtained from citronella bagasse (CB) and a mixture of citronella bagasse and paper mill sludge (CB + PMS) was determined employing the epigeic earthworm species Eisenia fetida. Two of the primary biological indicators—enzyme assay and germination index—were used for evaluation of vermicompost maturity. The enzyme assay includes the changes in dehydrogenase and urease activities in the final products. The test for germination index was performed on two economically important plant species Abelmoschus esculentus and Solanum melongena. The results revealed a significant increase in dehydrogenase and urease activities in the vermicompost samples over the raw materials and traditional compost. The enhancement was recorded 215.63–225.63% in dehydrogenase and 149.89–249.31% for urease in the end products obtained after 45 days of experimental trials. Further, the higher values of germination index in the vermicompost treatments as against the control confirm the suitability and stability of the vermicomposted final products.

Waste-to-energy or value-added products have been increasingly considered in many pulp and paper mills (PPMs) worldwide. However, developing appropriate conversion technologies is a major challenge in transforming PPMs wastes into biofuels or value-added biomaterials. In the present study, a long-term (320 d) anaerobic digestion of primary sludge of a thermomechanical pulp mill (TMP) was carried out for the first time in a thermophilic anaerobic membrane bioreactor (ThAnMBR). Effect of organic loading rate (OLR) in the range of 2.5–6.8 kg-COD/m3 d and hydraulic retention times (HRT) of 3–8 d on the process performance was investigated. Under various OLRs, stable biogas productions were obtained, and the best results were achieved with lower OLR (2.5 kg-COD/m3 d) and higher HRT (8 d), at biogas yields of 189 L biogas/kg MLSS fed. However, it was found that biogas production and sludge biomass degradation decrease when the organic loading rate increases. The proportion of sludge reduction ranged from 28.9 to 46.7% depending on the applied OLRs. Despite varying OLRs, stable membrane performance was obtained, where the required membrane flux was easily maintained during the reactor operation. In this study, also the properties of digestate and membrane permeates were studied under different operating conditions, and they fluctuated to some extent with OLR. ThAnMBR is a promising new technology for pulp and paper mill primary sludge treatment.

The textile industry is resource-intensive, which has a significant impact on global emissions and waste pollution. To meet the demand of textiles over a third of fibres used in manufacturing are sourced from fossil fuels. As the global demand for textiles continues to grow, manufacturers are having to seek innovative approaches to providing sustainable and regenerative cellulose fibres. However, the latest climate change pressures on the textile industry have uncovered grave environmental issues associated with traditional regenerative cellulose production, such as the viscose manufacturing process. The viscose process requires intensive use of hazardous chemicals which leads to water pollution and ecotoxicity. In addition, if forestry products are unsustainably sourced for this process, this can lead to resource scarcity and deforestation. To provide a holistic solution for mitigating these challenges this study uses the by-products of paper manufacturing dissolved in an ionic liquid to produce regenerated cellulose filaments. Paper mill sludge (PMS) is a cellulosic by-product typically used on animal bedding and land spreading. The material has been dissolved in an ionic liquid - 1-ethyl-3-methylimidazolium diethyl phosphate - with the aid of a co-solvent dimethyl sulfoxide (DMSO) - and spun into continuous filaments for textile production. The mechanical properties of paper sludge filaments are found to be competitive with commercial viscose, which is promising for their drop-in replacement. It is also demonstrated that by increasing the concentration of the PMS from 9% to 12.4%, an improvement of the filament properties can be achieved; an increase in modulus from ∼19 GPa to ∼26 GPa and strength from ∼223 MPa to ∼282 MPa. These values are shown to be competitive with other commercial, less sustainable, regenerated cellulose fibres.

Unprinting of paper can reduce multiple life-cycle stages in the recycling of paper to yield significant environmental impact. Laser-unprinting has been demonstrated for uncoated paper but causes significant damage to coated paper. This work explores a scalable optical (non-laser) process for unprinting coated paper. Printed coated paper is exposed to pulsed broad-spectrum Intense Pulsed Light (IPL) from a xenon lamp and the toner is then removed by dabbing gently with an ethanol wipe. While black toner is easily unprinted, unprinting of colored prints (red, blue, green) is best realized by incorporating an initial overprint of black toner. An unprinting throughput on the order of mm2/s is achieved. Three distinct regimes of unprinting are identified based on the extent of toner removal and damage of the paper. The optical properties of the unprinted paper, characterized via UV–Visible spectrophotometry, are correlated to these regimes to understand the potential for in-situ optical process monitoring. Scanning Electron Micrography and Fourier-Transform Infrared Spectroscopy are performed to understand the underlying mechanisms that govern the occurrence of the different unprinting regimes. Further, the potential impact of the developed approach on recycling of paper is discussed in the context of the capabilities of current optical unprinting approaches and the potential elimination of life-cycle stages in conventional paper recycling.

We have studied the surface structure of tamper-proof paper with positive and negative watermarks at different scales ‒ from a micrometer to a nanometer level, by using the methods of contact profilometry and atomic force microscopy. Experimental research has confirmed that the structural parameters of the tamper-proof paper's surface differ at regions with and without watermarks. The results of measurements by a contact profilometer have made it possible to trace a correlation between values of the profile's mean arithmetic deviation and the presence of watermarks. It was determined that the value for the profile's largest height does not depend on a measurement region, which could be related to the chaotic arrangement of fibers and particles of the filler in the paper bulk that protrude above the profile's line. By analyzing the value of the profile's mean arithmetic deviation obtained by using a method of atomic-force microscopy, it was found that for regions with negative watermarks it is larger than that for regions with positive watermarks. The dependence of the profile's largest height on measurement region is not clearly observed. This may be due to that the size of the examined region (3,000×3,000 nm) covers only part of the pulp fibers. Thus, the results of our analysis allow us to argue that both methods are suitable for estimating the characteristics of paper's surface, and determine the character of interaction between a given type of paper and printing inks during printing process. In particular, it has been established that the method of profilometry makes it possible to determine parameters of the paper's surface profile, formed in a certain way, while the atomic force microscopy method allows analysis of the morphology of its components, located at the surface (fibers, filler's particles, etc.). The availability of information on the structural properties of paper makes it possible to predict the quality of printing reproduction, specifically clearness of reproduction of thin guilloche lines on watermarks, which is relevant because it prevents flaws in printing products for special purposes.

The paper drying process has the highest level of energy consumption in the pulp and paper production process. Analysis and optimization of the energy system during the paper drying process is critical for improving the energy efficiency of the entire paper mill. In the existing model for the paper drying process, the solution requires accurate boundary conditions such as the air temperature and humidity of the pocket area and the cylinder surface temperature, which are very difficult to obtain in the papermaking process. This can result in significant deviations between the model solution and the actual production process. This paper focuses on the single-tier dryer cylinder-based paper drying process that has been widely used with high-speed papermaking machines in recent years. A mathematical model is proposed based on real-time data. The verification via industrial production demonstrates that the proposed model is reliable for the paper drying process. Based on the simulation results, two optimization operations have been proposed. The energy consumption decreases from 1.51 t steam/t paper to 1.44 t steam/t paper, 4.6% of the steam and 1.26 × 106 RMB can be saved for a medium-scale paper mill with the annual production capacity of 105 t paper.

Pulp and paper industry is one of the high priority sectors that generates large amount of solid (sludge) and liquid (paper mill effluent) wastes. Making use of this huge quantity of paper mill sludge (PMS) in an environment friendly manner is challenging and cost involving. Similarly the present wastewater treatment strategies based on physical and chemical methods encounter certain serious setbacks including secondary pollution generation with expensive mode of abatement processes. The present study aims at a “waste treats waste” strategy for the bioremediation of paper mill effluent in fluidized bed reactor (FBR) using another waste of the same industry, PMS as immobilizing matrix for Planococcus sp. TRC1, a wastewater bacterial isolate. This study simultaneously explores this isolate for the yellowish orange pigment it produces (2.3 ± 0.2 mg/gm of dry bacterial biomass) and characterizes it as a member of the pharmacologically important carotenoid pigment family via UV-Vis spectrophotometry, TLC, FT-IR and 13C NMR. The antioxidant potential of this pigment was studied by DPPH assay (IC50 = 33 ± 0.4 μg/ml) and H2O2 assay (IC50 = 147.4 ± 2.2 μg/ml). In FBR, the PMS immobilized bacteria showed removal of phenol, lignin, colour and COD from the effluent by 96%, 74%, 81% and 85% respectively after 60hr of treatment. The experimental data on immobilization fitted well with pseudo second-order (R2 = 0.955) and Freundlich adsorption isotherm (R2 = 0.996) models. The alterations in PMS before and after bacterial immobilization, as revealed by SEM and FT-IR, depicted the success of PMS as immobilization matrix. Phytotoxicity (90% seed germination) and mutagenicity studies confirmed that the treated effluent was substantially less toxic than its raw state. This study highlights a novel utilization possibility of PMS in an eco-friendly and economic way as immobilization matrix for Planococcus sp.TRC1 for paper pulp mill effluent treatment along with production of carotenoid pigment from this potential bacterial isolate as value added product.

Ample interest for more efficient utilization of bio-based residues has emerged in the Nordic pulp and paper (P&P) industry, which uses virgin wood as feedstock. Although different bioenergy retrofit technologies for production of liquid, solid, and gaseous bioenergy products have been applied in the existing P&P mills, the number of installations remains small. The lack of profound knowledge of existing bioenergy retrofits hinders the replication and market uptake of potential technologies. This review synthesises the existing knowledge of European installations and identifies the key drivers and barriers for implementation to foster the market uptake of potential technologies. The bioenergy retrofits were reviewed in terms of technical maturity, drivers, barriers and market potential. Based on this evaluation, common drivers and barriers towards wider market uptake were outlined from political, economic, social, technical, environmental, and legal perspective. Technologies already commercially applied include anaerobic fermentation of sludge, bark gasification, tall oil diesel and bioethanol production, whereas lignin extraction, biomethanol production, hydrothermal liquefaction and hydrothermal carbonization are being demonstrated or first applications are under construction. The findings of this review show that a stable flow of residues at P&P mills creates a solid base for retrofitting. New innovative bio-based products would allow widening the companies' product portfolios and creating new businesses. Also, European Union's (EU) legislation drives towards advanced biofuels production. Wider uptake of the retrofitting technologies requires overcoming the barriers related to uncertainty of economic feasibility and unestablished markets for new products rather than technical immaturity.

To evaluate the effect of brown-rot fungi Oligoporus placenta and earthworm Eisenia fetida on decomposition of paper mill sludge, the paper mill sludge was mixed with cow dung in 0, 25, 50, 75, and 100% proportions and changes in physicochemical quality of waste mixtures was carried out for 28 days. All waste mixtures were treated with: Setup-I (E. fetida), Setup-II (O. placenta) and, Setup-III (E. fetida + O. placenta). A decrease in total organic carbon, C/N ratio and cellulose but an increase in total kjeldhal nitrogen, total phosphorus, total potassium and pH was recorded. The paper mill sludge in 50–75% proportion in feedstock showed the better results and rate of mineralisation were in order: Setup-III > Setup-I > Setup-II. The proportion of CD has direct role in waste mineralisation. The microbial population (bacterial, fungal and actinomycetes) and earthworm biomass were also high in Setup-III, suggesting the influence of brown-rot fungi on paper mill sludge humification. Results indicate that fungal inoculate in vermicomposting was effective in decomposing cellulose-rich industrial sludge.

The non-process-elements (NPE's) in the pulp and paper production, in particular chloride (Cl−) and potassium (K+), eventually accumulate in a sodium sulfate recovery cycle of a paper plant, especially on boiler fly ashes (flue gas cleaning). This accumulation often leads to fouling and corrosion. Thus, in order to reduce such problems, a leaching unit is typically integrated aiming to remove Cl− and K+ and recover sodium sulfate (Na2SO4) from boiler fly ashes. In this context, this research is focused on investigating the effects of temperature, ash concentration and pH on the separation efficiency (Cl− and K+ removal and Na2SO4 recovery) of recovery boiler fly ashes using design of experiments in a devised laboratory setup. As expected from the literature, the results obtained reveals that concentration has the most significant effect on the response variables followed by temperature; whereas pH, not mentioned in this application so far, also has a significant effect. The optimum operating condition, which yields 84 wt% of Na2SO4 recovery and 97 wt% of Cl− and K+ removal, is achieved at 60 °C, 50 wt% of ash and pH 9.0. For practical applications, this optimal condition reduces the accumulation of NPE‘s and mitigates the risks of fouling and corrosion.

Dewatering and handling of pulp and paper mill sludge is challenging and often comprises more than half of the overall wastewater treatment costs at a mill. Primary sludge is usually more dewaterable than biosludge (waste activated sludge), and the ratio between both types of sludge largely determines the dewaterability of the sludge mix. This study has quantified the benefits of adding primary sludge to biosludge to enhance the dewaterability in terms of cake solids and filtrate/pressate solids content. Furthermore, the effects of the particle size distribution and the monovalent to divalent cation ratio of the various types of sludge were investigated. Biosludge and three types of primary sludge from a Canadian pulp and paper mill were mixed at various ratios and tested for dewaterability using a Crown Press®, a bench-scale device which simulates industrial belt press dewatering. Results show that after addition of primary sludge at up to 40% mass proportion (dry solids basis) the dewatered cake solids content increased substantially, from 10.4% to 18.7–19.9%, depending on the type of primary sludge added. Further addition of primary sludge led to comparably only small improvements. Primary sludge addition also resulted in decreased total suspended solids (TSS) concentrations in the combined gravity filtrate / Crown Press pressate. Primary sludge content of only 10% in the sludge mix was sufficient to decrease the TSS concentration from 1.8 g/L to 0.2 – 0.4 g/L. The study shows that only less than half of the sludge mix needs to consist of primary sludge, in order to achieve adequate dewaterability. This opens up the possibility of retaining more primary fiber within the pulping process, without compromising downstream sludge dewatering.

There are many pulp and paper industries all around the globe and in Ethiopia as well different companies are involved in the production and distribution of paper and paper products. Most of the industries especially those in developing countries like Ethiopia produce paper from pulp obtained from wood cellulose. Ethiopia is not producing its pulp and mostly the paper industries depend on imported pulp or recycled paper. There are critical limitations in synthesizing pulp and paper from wood-based cellulose resources mainly the scarcity of wood in some countries and the impact on altering the ecological balance and through frequent deforestation and replantation practice. The present review assesses the potential sources from non-wood resources which can be used as a substitute cellulose raw material for the pulp and paper industry. The study encompasses possible beneficiation routes for manufacturing pulp from non-wood cellulose resources available in Ethiopia for diversified application in the paper industry. With this regard, potential non-wood raw materials for pulping are assed in line with the fulfilment of the target for import substitution strategy, the realization of a safe working environment, and socio-economic betterment of the nation with specific reference to the paper industry.

In recent years, the use of microalgae as feedstock for many marketable products, such as animal/aqua feeds, bioplastics and fertilizers, has gained renewed interest due to their fast growth potential coupled with relatively high lipid, carbohydrate and nutrient content. An algal biorefinery at an industrial site has the potential to sustainably and profitably convert carbon dioxide emissions into microalgal biomass and concomitantly reduce nitrogen and phosphorus from wastewaters. Industrial wastewaters are a potential alternative to traditional media used for large-scale microalgal cultivation. Pulp and paper mills are major consumers of water resources and discharge a huge amount of water to nearby lakes or rivers. This study investigated whether pulp and paper mill waste water is suitable for microalgal cultivation with the aim of achieving significant biomass production. Six different process waters from one Canadian pulp and paper mill were tested with two freshwater green microalgae. All of these waters were unable to support growth of microalgae due to inadequate nutrient concentrations, colour, turbidity and possible toxicity issues. HIGHLIGHTS Two freshwater microalgae strains were screened for potential growth on pulp and paper effluents.; Pulp and paper wastewater effluents were unable to support growth of the microalgae.; Chemical residues from the pulping process, such as peroxide and tannin, may inhibit algal growth.

© 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.The present paper reports the pyrolysis behavior, kinetic, and thermodynamic parameters of paper mill sludge (PMS), which is a paper manufacturing residue and cannot be re-evaluated, at three heating rates (5, 10, and 20 °C min−1) under non-isothermal conditions. Ultimate and proximate analyses of the paper mill sludge were carried out. Kinetic and thermodynamic parameters were calculated using four model-free methods; Flynn-Wall Ozawa (FWO), Friedman, Kissinger-Akahira-Sunose (KAS), and distributed activation energy model (DAEM). High R2 values revealed that all models are compatible with TGA data. The activation energy calculated (101.01 kJ mol−1) from FWO was higher than the other three methods. Pre-exponential factor values ranged from 0.56 × 103 and 14.55 × 103 s−1 for all methods. Kinetic and thermodynamic findings will be beneficial in terms of the process design of PMS pyrolysis. Graphical abstract: [Figure not available: see fulltext.]

Microbial fuel cell is a promising technology to harvest energy from wastewater, and effective anode catalysts are essential for its applications. In this study, zero-dimension nitrogen-doped carbon dots, as biocompatible efficient modifiers, were synthesized and decorated onto the carbon paper surface to prepare microbial fuel cell anode. The as-fabricated nitrogen-doped carbon dots decorated carbon paper anode was able to enhance electricity generation and efficient wastewater treatment. It was found that the as-fabricated electrode had a high hydrophilicity, which was favorable for the microbial immobilization. Compared with the carbon paper anode, the biofilm on the as-prepared anode was almost twice of thickness. After introducing nitrogen-doped carbon dots, the extracellular electron transfer process from the microorganisms to the anode was enhanced. The microbial fuel cell with the as-developed anode generated a remarkable power output of 0.32 mW, 1.1 times higher than that of the raw carbon paper anode with same measurement area. Moreover, 16 sRNA pyrosequencing analysis shows that the quantity of Pseudomonas on the electrode increased by ∼40%, which also promoted the electron transfer rate by excreting mediators like phenazines or phenazine derivatives. This work developed a new approach to design microbial fuel cell anode material and fabricate a high-efficiency and environmentally friendly anode for electricity generation from wastewater.

This study estimates efficiency in energy utilization at firm level and feasible energy saving target of the pulp and paper industry in India. For this analysis, data is extracted from prowess database for a panel of 67 major pulp and paper producing firms over the period of 2003–04 to 2013–14. We employed radial and non-radial variants of data envelopment analysis to assess the feasible energy saving target with the current level of output. Particularly, we employed slack-based method with variable returns to scale as a flexible and pragmatic approach to performance analysis. Results reveal no significant improvement in the energy efficiency level of the firms over the study period and show vast energy saving potential. Results of slack-based measure of energy efficiency show the feasible energy saving potential of 40%. Further, size of the firm, age and financial performance are important factors that influence energy efficiency. Therefore, this study recommends special attention to the paper industry while implementing energy efficiency programme. We also reviewed four major policies for industrial energy efficiency improvement initiated by Bureau of Energy Efficiency, India.

Small companies encounter difficulties to adapt to new markets with a sustainable perspective. The subject of this article is a paper transformation company which has been eager to develop the organic farming market by developing a new plant support. Alternatives made from plant fibres or plastics exist, such as jute and polypropylene. The main difficulty of this project was to ecodesign a paper product with a multicriteria approach. The factors considered have been divided into two categories. Firstly, the environmental impacts calculated according to the Life Cycle Assessment methodology (on raw material extraction, manufacturing and end-of-life) are summarised. Secondly, the characteristics of the product are discussed in regards to these results and sustainability questions as part of the interpretation phase. Finally, ways of improvement of the LCA methodology to improve the study in terms of geographical representativeness and societal considerations are discussed.

Transformer insulation paper is a key indicator for transformer remaining operational life. Paper decomposition is evaluated using the degree of polymerization (DP) which calls for samples of insulation paper from operating transformers. Since collecting such paper samples is extremely difficult, other indicators have been used to indirectly reveal the DP value of insulation paper. This includes dissolved gases in transformer oil such as carbon oxides and hydrocarbon gases, furan compounds, methanol, ethanol, and moisture along with some oil characteristics such as interfacial tension. However, for the same oil sample, these individual parameters lead to different DP values. This is attributed to the lack of accuracy of the established mathematical and artificial intelligence models correlating DP with each of the above mentioned individual parameters. This paper presents a self-learning method to estimate the DP value of transformer insulation paper based on multiple transformer oil aging parameters. The proposed method comprises data processing, fuzzy c-means and linear regression. Results reveal that estimating the DP value based on multiple aging parameters is more accurate than estimating it using one single parameter as per the current practice. The proposed method not only helps to understand the correlation between multiple oil aging parameters and the DP value of paper insulation, but also promotes the establishment of more accurate life assessment models for power transformers based on these oil aging parameters.

This paper shows how chemical sludge (CS) generated during wastewater treatment at a paperboard mill can be quickly dried at low-temperature and employed in bark-fired boilers to reduce slagging and corrosion problems. By using a cyclone-dryer operated at an inlet-air velocity of 110 m/s and a temperature of 90 °C, the dry-matter content of CS was increased from approximately 19 to 82%. The residence time of CS inside the cyclone was approximately 2 s when using the inlet-air velocity mentioned above. Disaggregation of the feedstock caused by collisions with the cyclone wall and between particles played a crucial role in enhancing the efficiency of heat and mass transfer. Three co-pelletized mixtures of Scots pine bark (SPB) and dried-CS were combusted in a 40 kW fixed-bed burner. Flue gas analysis was performed with a gas analyser. Coarse and fine ash were analysed by SEM-EDS and XRD. NOx and SO2 emissions increased with increasing amount of CS in the mixtures. Mono-combustion of SPB resulted in a large quantity of slag (i.e., molten ash) with a high degree of sintering (i.e., hardness of the slag), and ash deposits formed on heat transfer surfaces were rich in K2SO4 and KCl. Mixtures of SPB and CS were less prone to slagging, and the amount of alkali chloride in the deposits was reduced in favour of alkali sulphate formation.

Using waste paper as fuel for domestic heating is a beneficial recycling option for small island developing states where there are lacks of resources for energy and waste treatment. However, there are concerns about the impact of air pollutants emitted from the burning of the self-made paper briquettes as household air pollution is recognised as the greatest environmental risk for human. In this study, combustion tests were carried out for paper briquettes made in one Pacific island and three commercial fuels in Australia including wood briquettes, kindling firewood and coal briquettes in order to: 1) characterise the emissions of three criteria air pollutants including particulate matters, CO and NOx including their emission factors (EF) from the tested fuels; and 2) compare the EFs among the tested fuels and with others reported in the literature. The results showed that waste paper briquettes burned quickly and generated high temperature but the heat value is relatively low. Paper briquettes and coal briquettes produced higher CO concentration than the others while paper briquettes generated the highest NOx level. Only PM2.5 concentration emitted from paper briquettes was similar to kindling firewood and lower than wood briquettes. Burning of paper briquettes and wood briquettes produced particulate matter with large average count median diameter (72 and 68 nm) than coal briquette and kindling firewood (45 and 51 nm). The EFs for CO, NOx and PM2.5 of paper briquettes were within the range of EFs reported in this study as well as in the literature. Overall, the results suggested that using paper briquettes as fuel for domestic heating will not likely to generate higher level of three major air pollutants compared to other traditional fuels.

Anaerobic treatment of sedimented fibers collected from bottom of a bay that had been receiving pulp and paper mill wastewater for about 70 years were studied for the first time in semi-continuously fed continuously stirred tank reactors (CSTR). Anaerobic treatment of the fiber sediment was shown to be feasible, without dilution and with nitrogen and buffer supplement, at organic loading rates (OLR) up to 2.5 kg VS/m3d and hydraulic retention times (HRT) of 60 d resulting in methane yields of 201 ± 18 L CH4/kg VS. Co-digestion of sedimented fiber with sewage sludge at an OLR of 1.5 kg VS/m3d and HRT of 20 d resulted in a methane production of 246 ± 10 L CH4/kg VS. The techno-economic feasibility of mono and co-digestion process together with several case dependent factors such as maximum operable OLR, digestate utilization needs to be evaluated before making further conclusions for larger scale remediation applications. acceptedVersion

The pulp and paper (P&P) sector is a dynamic manufacturing industry and plays an essential role in the Austrian economy. However, the sector, which consumes about 20 TWh of final energy, is responsible for 7% of Austria’s industrial CO2 emissions. This study, intending to assess the potential for improving energy efficiency and reducing emissions in the Austrian context in the P&P sector, uses a bottom-up approach model. The model is applied to analyze the energy consumption (heat and electricity) and CO2 emissions in the main processes, related to the P&P production from virgin or recycled fibers. Afterward, technological options to reduce energy consumption and fossil CO2 emissions for P&P production are investigated, and various low-carbon technologies are applied to the model. For each of the selected technologies, the potential of emission reduction and energy savings up to 2050 is estimated. Finally, a series of low-carbon technology-based scenarios are developed and evaluated. These scenarios’ content is based on the improvement potential associated with the various processes of different paper grades. The results reveal that the investigated technologies applied in the production process (chemical pulping and paper drying) have a minor impact on CO2 emission reduction (maximum 10% due to applying an impulse dryer). In contrast, steam supply electrification, by replacing fossil fuel boilers with direct heat supply (such as commercial electric boilers or heat pumps), enables reducing emissions by up to 75%. This means that the goal of 100% CO2 emission reduction by 2050 cannot be reached with one method alone. Consequently, a combination of technologies, particularly with the electrification of the steam supply, along with the use of carbon-free electricity generated by renewable energy, appears to be essential.

A new process for the production of bioethanol from paper mill sludge (PMS) is described in this work. PMS biomass feedstock was processed via the simultaneous saccharification and fermentation (SSF) with and without accelerants. The enzymatic hydrolysis and fermentation were first evaluated, and the energy demand was 2.2 MJ/L of produced ethanol. When the enzymatic hydrolysis and fermentation were combined, the energy demand was reduced to 1.0 MJ/L ethanol, the sugars production increased, and the overall capital cost of the process decreased. The sugar yield was improved by adding accelerant and selecting the optimal fiber recovery method. The accelerant improved the enzymatic hydrolysis via a pathing/bridging mechanism. The SSF with the chemical fiber recovery method coupled with accelerant addition would be the best process configuration. Upon this combination, the glucose profile was enhanced from 9.8 g/L to 17.0 g/L. The sludge fiber conversion by SSF was improved by selecting an efficient fiber recovery method combined with the accelerant addition. SSF in chemical fiber recovery with accelerant addition was the best process by a 10% improvement of ethanol yield. The proposed process configuration offers a lower cost and sustainable process and contributes to the circular economy of zero waste discharges.

The main aim of the study was to assess the environmental performance, through the application of the life cycle assessment, of a recycled paper production process focusing on the energy aspect. The production process occurred in a paper mill that produces packaging paper using paper and cardboard from source separation of municipal solid waste as raw materials. Two scenarios (S1 and S2) were defined by their energy supply sources. A cogeneration (CHP) system using natural gas for the combined production of thermal and electric energy was the source in S1. The Italian electricity grid (using the Italian country mix) and a natural gas boiler were the separate sources for electric and thermal energy, respectively, in S2. Finally, in order to evaluate the environmental effects on the results of the study about the variation in the natural gas supply source, four alternative Italian import mixes (M1, M2, M3, and M4) were defined by varying the contribution of the supplier countries. The environmental impacts were evaluated with ReCiPe 2016 (H) using both midpoint and endpoint approaches. The results showed that for both the scenarios, the energy consumption was the main cause of impacts mainly because of the natural gas contribution. The presence of the cogeneration (CHP) system generated significant environmental benefits compared with the use of energy provided by more conventional sources. The production and use of chemicals as well as the disposal of waste produced during the paper production were other environmental hotspots. The variation in the composition of the Italian import mix of natural gas, in terms of the supplier country’s contribution, had a significant influence on the results. The import of natural gas from Russia was the most impactful option. Since Russia is the country that contributes to the Italian import mix the most, in the next years, the use of natural gas in Italy could become increasingly impactful. Therefore, the replacement of natural gas with renewable sources is an urgent priority.

PurposeThis position paper urges a drive towards clarity in the key definitions, terminologies and habits of speech associated with digital engineering and building information modelling (BIM). The ultimate goal of the paper is to facilitate the move towards arriving at an ideal definition for both concepts.Design/methodology/approachThis paper takes the “explanation building” review approach in providing prescriptive guidelines to researchers and industry practitioners. The aim of the review is to draw upon existing studies to identify, describe and find application of principles in a real-world context.FindingsThe paper highlights the definitional challenges surrounding digital engineering and BIM in Australia, to evoke a debate on BIM and digital engineering boundaries, how and why these two concepts may be linked, and how they relate to emerging concepts.Originality/valueThis is the first scholarly attempt to clarify the definition of digital engineering and address the confusion between the concepts of BIM and digital engineering.

This study develops a framework of internal and external factors that influence the adoption of eco-innovation. We studied 80 adoption processes in the Dutch brewing industry and the Dutch paper industry and analysed the relative importance of different factors. We find that internal factors were more important than external factors. The analysis also shows differences between the industries. The financial advantage was important for both industries, but especially for the paper industry. For the brewing industry, ethical responsibility and stakeholders played a more important role in the adoption. The analysis also revealed differences for small and large firms. Ethical responsibility and stakeholders are relatively more often mentioned by small firms, whereas clear objectives and regulations were mentioned more by large firms. Our study highlights that the adoption of eco-innovation is a complex process and the position in the supply chain as well as the size of a firm influence what is important in the adoption of eco-innovation.

Thermal switches control thermal circuits and are widely used in electronics and engineering. Shape-memory alloys can be deformed by heating, which is widely used as a driving part for ther...

The pulp and paper industry, which provides cellulose pulp and paper, bio-based energy and chemicals, is one of the largest energy consumers, greenhouse gases (GHG) and pollutant emitters among manufacturing industries. Although the environmental impact of the pulp and paper industry has been extensively studied, life cycle assessment (LCA) results have not yet reached a consensus. By means of a systematic review and meta-analysis, this article contributes to the quantification and harmonization of the life cycle environmental impacts of pulp making and paper making systems. Based on the screening of 45 cases of paper making and 18 cases of pulp making, we found that 1 t of paper results in about 950 kg carbon dioxide (CO2) equivalent (CO2-eq) GHG emissions on average. However, there are distinct differences between countries and pulp and paper categories. The dominant factor influencing GHG emissions is energy use. In paper making, the pulp making process is responsible for 62% of energy use, 45% of GHG emissions, 48% of acidification potential, and 49% of eutrophication potential. The kg CO2-eq emissions of three different types of pulp were as follows: Kraft, 508 kg CO2-eq/t; chemi-mechanical, 513 kg CO2-eq/t; and recycled pulp, 408 kg CO2-eq/t. Excluding emissions from electricity and steam production, the convergence of carbon emissions is observed within the same categories of pulp. Straw-based pulp caused far more environmental impact than any other type because of the intensive inputs in agricultural activities as well as in the pulp making process. This research highlighted the inconsistencies in functional units, system boundaries, and methodologies and carbon neutrality assumptions in different LCA studies of pulp and paper making. Future studies should focus on the environmental impact of straw-based pulp making, system boundary unification, and calculation of biogenic carbon emissions.

In remote areas, such as India, Africa and Southeast Asia, typically not connected to the natural gas distribution network, tissue paper production is currently carried out using a Yankee cylinder and two hot air hoods heated with saturated steam produced in conventional boilers. In this way the drying air is heated at medium temperature, around 160-180 °C, with consequent low levels of dried paper production. In this context, the present study intends to evaluate the technical and economic feasibility of using a wood biomass fixed bed downdraft gasification plant for the production of syngas to be used as fuel in gas hoods, in order to reach high drying temperatures (around 500 °C), comparable with those of the current modern hoods powered with natural gas. Using previously developed calculation codes, an evaluation of energy performance of the paper drying system and of the gasification plant has been performed. The present study also evaluates the possibility of applying a CHP plant, powered by biomass, for the production of steam and electric, this last obtained adopting a steam turbine, thus covering all the electrical and thermal needs of the paper mill. Results show that, for a paper mill with a production of about 80 t/day of paper, two gasification reactors with a thermal output of about 1.95 MWt, and a consumption of dry biomass of 0.86 t/h, are required. For the steam system, the net electric power needed to meet the needs of the paper mill is about 3100 kW with a consumption of 4.72 t/h of moist biomass and a net efficiency of 23.9 %.

The need to view innovation policy through the lens of policy mixes has gained momentum given the growing complexity, the dynamics of real-world policy and the wide array of difficulties to address the current great societal challenges, notably the increasing pressure on the ecosystems that support our society. One of the main challenges concerning the transition towards bioeconomy, is to gain a more in-depth understanding on the policy mix to stimulate innovation in sustainability transitions. Our paper aims at enriching the portfolio of empirical case studies on policy mixes for innovation and sustainable transitions, by investigating the development of the policy mix underpinning the sustainability transition of the pulp and paper industry in Sweden. We apply a case study approach which draws on event history analysis, semi-structured interviews with industry and policy makers, literature reviews, a participative workshop with stakeholders from the pulp and paper industry, as well as on the IEA databases on climate change and energy efficiency policies and measures. Our analysis emphasises coordination, timing and scale in policy mixes as important elements to understand how instruments interact to accelerate sustainability transitions. The mapping of the policy mix shows that destabilising policies were crucial for accelerating the transition process of the industry. Prior to novelty creation policies, destabilising policies (e.g. environmental policies) were needed for 'innovation policy instruments' to be effective. More specific instruments (e.g. carbon tax), targeting particular functions of the innovation systems, require 'on-the-ground' policy intelligence and benefit from close interaction with industry.

The pulp and paper industry, one of Canada’s largest and most important industries, produces many by-products, some of which are used to produce electricity and steam for mill operations; however, the by-products are not used economically. The industry has been facing financial challenges and, therefore, an appropriate means of converting by-products to value-added products is highly desired. In this study, we explore nine pathways for the conversion of black liquor, the major by-product of the industry, to different value-added final products. These include steam, electricity, dimethyl ether, Fischer-Tropsch liquids, mixed alcohols, methanol, acetone, butanol, ethanol, and lignin. The most economical conversion pathway is selected based on the internal rate of return (IRR) calculated through a techno-economic assessment. Lignin production through the fractionation of black liquor is the most attractive scenario. Sensitivity and uncertainty analyses were performed on the IRR for the lignin production scenario to evaluate the effect of different parameters on overall performance and assess the accuracy of the results. The sensitivity analysis shows that lignin price and operating costs are the most influential parameters on IRR. This study offers insights into options of revenue generation for the pulp and paper industry through the innovative use of its by-products.

The activated sludge process within the pulp and paper industry is generally run to minimize the production of waste activated sludge (WAS), leading to high electricity costs from aeration and relatively large basin volumes. In this study, a pilot-scale activated sludge process was run to evaluate the concept of treating the wastewater at high rate with a low sludge age. Two 150 L containers were used, one for aeration and one for sedimentation and sludge return. The hydraulic retention time was decreased from 24 hours to 7 hours, and the sludge age was lowered from 12 days to 2–4 days. The methane potential of the WAS was evaluated using batch tests, as well as continuous anaerobic digestion (AD) in 4 L reactors in mesophilic and thermophilic conditions. Wastewater treatment capacity was increased almost four-fold at maintained degradation efficiency. The lower sludge age greatly improved the methane potential of the WAS in batch tests, reaching 170 NmL CH4/g VS at a sludge age of 2 days. In addition, the continuous AD showed a higher methane production at thermophilic conditions. Thus, the combination of high-rate wastewater treatment and AD of WAS is a promising option for the pulp and paper industry. Funding agencies: Swedish Energy Agency [32802-2]; Scan-dinavian Biogas Fuels AB; Poyry AB; BillerudKorsnas AB; SCA; Fiskeby Board AB; Purac AB

Activating flux is made up of inorganic material mixed with a volatile medium. The objective of this study is to identify and review the literature in activating flux, and different type of welding techniques. For that purpose, a structured review method is adopted and the Scopus database is used as a primary source for the selection of papers. The papers were identified using the string term of “Activating flux” OR “Activated flux” in the title of papers. And a total of 238 papers were identified for the study. Besides the above few other papers were also reviewed and the materials used, the type of flux used, and the findings of different combinations were highlighted in the form of tables. The findings of the study provide a comprehensive understanding of the different type of welding techniques focusing on TIG welding, and the different combination of flux used and their impact was summarized.

Every year the pulp and paper industry consumes billions of metres cubed of water and produces huge amounts of highly polluted wastewater that needs to be treated. Conventional techniques of wastewater treatment require a high energy input and their environmental impact is debatable. Thus, the need to find new sustainable, environmentally friendly and efficient treatment techniques is urgent. Microbial fuel cells (MFC) are the technology of the future since they simultaneously treat wastewater and produce clean energy. The historical development of this technology towards its application to wastewater treatment was described. The application of MFCs in pulp and paper wastewater treatment is a new and developing field of investigation that still needs to overcome many limitations before its use on an industrial scale. This article reviews the limits of conventional treatment methods and the current state of the art MFC systems for pulp and paper wastewater treatment. The paper provides an overview of the electrogenic microorganisms able to produce electricity from pulp and paper wastewater. The bacteria, isolated at different stages of pulp and papermaking, are best suited for electrogenic activity in harsh environments. It was shown that MFC technology fully meets the requirements of sustainable pulp and paper wastewater treatment and, in terms of the input-output energy balance, remains energetically and environmentally competitive when compared to conventional treatment methods.

The increasing pressure on natural resources and the climate has been noted by businesses and governments worldwide, who now face the difficult task of integrating paths of environmental sustainability and economic growth. One promising approach to sustainable development, reducing the pressure on natural resources and solving waste problems is circular economy. From different ways of implementing circular economy, this study focuses on the productization of industrial side streams, which carry a great deal of underutilized potential. In this article, the productization of pulp and paper industry side stream, fiber sludge, for commercial use as a dust-binding agent is studied via a descriptive, in-depth case study. Apart from inconsistent quality, fluctuating supply, cost of storage and logistics, what makes industrial side stream utilization challenging is the lack of knowledge that stakeholders have about side streams and their utilization and the lack of new value chain development for their commercial use. Therefore, it is essential for all parties involved to have a clearer vision of what is being sold for what purposes, through productization. This study found that the productization of side streams follows the same steps as the productization of any other traditional product, and the productized side streams can be added to the company&rsquo, s product portfolio as by-products.

Due to the increasing use of intermittent renewable generation, the power grid requires more flexible resources to balance supply and demand of electricity. Steam systems with turbine-generators, which are widely used in industries, can be operated flexibly to support the power grid. Yet, the available amount of flexibility of industrial steam systems is still not clearly quantified. This study presents the method to quantify electricity generation flexibility of a typical industrial steam system with a steam turbine-generator and process heat demands. The proposed method is introduced based on a real case of an integrated pulp and paper mill in Austria. An integrated mathematical model representing the combined electricity and steam system is developed to simulate the behaviour of the on-site energy system to quantify the potential flexibility provision. Flexibility is represented as the maximum upward and downward changes in the imported electricity from the public power grid. The results demonstrate that it is possible to aggregate the flexibility of the industrial facility as a lookup table. Also, the results reflect key factors that limit the flexibility at different operating points of the turbine-generator.

With the surging energy price and environmental concerns, measures to improve energy efficiency have attracted increasing concerns of the manufacture sector, especially energy-intensive manufacturing industries such as tissue paper mills. Energy-efficiency scheduling, as a novel energy-efficient method, has attracted the attention of an increasing number of researchers in recent years. Drying process is the most energy-intensive production process in tissue paper mills, which has a great energy-saving potential. This paper aims to reduce the energy costs for the tissue paper mill, consisting of processing energy cost and set-up energy cost, through integrating drying process optimization with energy-efficient scheduling. First, the energy cost model and the scheduling model were built. Then, the energy cost of the drying process of every job in a given scheduling problem was optimized using particle swarm optimization (PSO). Afterwards, the energy cost was further optimized using energy-efficiency scheduling. In addition, a hybrid non-dominated sorting genetic algorithm II (NSGA-II) was utilized to solve the energy-efficiency scheduling problem. Finally, several real scheduling problems from a real tissue paper mill were addressed using the proposed approach to demonstrate its effectiveness in energy saving. The experiment result showed that there is a great energy-saving potential in the drying process, accounting for up to 12.53% of the total energy consumption. Moreover, the maximum energy saving ratio of the proposed approach could reach 9.03%. On the whole, the proposed approach can provide a new energy-saving method for tissue paper mills or other manufacturing industries.

The paper and cellulose manufacturing industry generates significant quantities of waste, including an extremely humid sludge, which is considered to be an effluent with high environmental liability for the manufacturer. Studies have shown that this waste sludge may be utilized in construction material, such as mortar for fixing blocks, as well as for ceiling and wall coatings that use ceramic masonry as a sealant. The recycling of pulp and paper industry waste sludge has important environmental benefits, by preventing soil and water pollution caused by inadequate disposal and by reducing the depletion of natural resources, such as lime, used in cementitious materials. This study analyzed the sustainability of incorporating such waste into cement-based mortars. Tests were conducted replacing lime, one of the most expensive mortar components with high environmental impact, with waste sludge in contents of 5%, 10%, 15%, and 20%. Analysis was then performed on the samples to assess the primary technical characteristics of these incorporated mortars, such as the consistency index, heat of hydration, content of incorporated air, water retention, mechanical strength and the capillarity coefficient. The results were compared with the results of the characterization tests that were performed on the waste material. The results showed that for use in wall and ceiling mortar coatings, the level of incorporation should not exceed 10%, because higher levels yield lower values of mechanical strength resistance, incompatible with market requirements. This result is probably due to the low heat of hydration of the waste material which generates slower reactions. On the other hand, higher levels of waste material content, above 10%, are appropriate convenient for mortar used to fill small repairs in masonry that do not require control of properties.

Color removal from pulp and paper mill wastewater by using fly ash was one of the effective and low-cost methodologies to improve the quality of the wastewater. The fly ash had the capability to remove various organic pollutants, such as Lignin, Tannins, Humic, and Fulvic, from wastewater. These organic pollutants contribute to the color intensity of industrial effluent. The research examined the removal capability of fly ash including Bagasse fly ash, Rice husk ash and Lignite fly ash. The samplings were analyzed in the laboratory for color removal capability. The test was divided into 3 steps as follows: Step 1 the comparison of color removal efficiency by using 3 types of fly ashes; Bagasse fly ash, Lignite fly ash and Rice Husk ash. Step 2: Analyzing the functional group of fly ashes before and after color removal by using the Fourier Transform Infrared Spectroscopy (FT-IR) to determine the adsorption mechanism and other influencing factors. Step 3: Color removal efficiency by sand filter experiment. The results showed that; Step 1: Bagasse fly ash, Rice husk ash and Lignite fly ash were effective in color removal of 94.2, 74.8 and 71.8 percent at 30 minutes, 24 hours and 4 days, respectively. The pH of the effluent using Bagasse fly ash was constant to 7.5 - 8 and tend to be constant although the ash amount increased, while the pH of Lignite fly ash was in the range of 8 - 9 and tend to increase when amount increased. Step 2: Analyzing the functional group of Bagasse fly ash using the FT-IR found that after using Bagasse fly ash for color removal in the effluent, the graph tends to decrease. Step 3: The result showed that the efficiency of color removal of the sand filter by soil mixed with Bagasse fly ash at ratio 1: 0 - 1:10 (Soil : Bagasse fly ash), which the efficiency of color removal tends to increase with the maximum of 93 % and the minimum of 16% at ratio 1:7 and 1:0, respectively.

This work was partially funded by H2020-ICT-2014-1, RIA, ERC-CoG-2014, and FEDER funds through the COMPETE 2020 Program and National Funds through FCT -Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2019. Large-area paper batteries have been explored in this paper, correlating electrode materials and screen printing with the electrochemical performances. The use of office paper embedded in salt solution with two electrodes performed by an easy and large-scale application technique opens doors to a new concept of energy storage. The proposed device is Li-free and uses zinc and silver powder-based screen printable pastes to deposit the electrodes. Cyclic voltammetry and charge-discharge curves reveal the performance of the produced devices using NaCl and KOH solutions in different concentrations. The simulation of electrochemical impedance spectroscopy measurements gave clue of a similar working mechanism to conventional Li-ion batteries. After charging, a single paper battery achieves 1.83 V with 60 mA/cm2 and 90.6% charge-discharge efficiency. As a proof of concept, a small paper battery and a set integrated in series and parallel were used to power a commercial red light-emitting diode. publishersversion published

The amount of Paper Board Mill Effluent Treatment Plant Sludge (PBM-ETPS) dumped from paper mills are huge and its conversion into hydrochar for the purpose of energy has broad prospects. This study investigated the optimum conditions for the production of PBM-ETPS derived hydrochar (PBM-ETPSH) through Reponse Surface Methodology (RSM) for more surface area and pore volume with minimal hydrogen to carbon (H/C) and oxygen to carbon (O/C) ratios. The PBM-ETPSH had higher heating value (HHV) of 18.39 MJ kg−1 with fixed carbon percentage of 15.6. Our results showed a reduction in H/C (35.05%) and O/C (43.7%) ratios confirming the coalification of optimized PBM-ETPSH. Thermogravimetric investigations of blending PBM-ETPSH with coal in 1:1 ratio increased its HHV to 22.25 MJ kg−1 making it suitable as an energy alternative for paper mills.

The Swedish pulp and paper industry (PPI) must increase energy efficiency to remain competitive on the global market, which has experienced entries from countries with cheaper energy and raw material supplies. Interactions among variables for energy use, production, energy management, electricity price and firm characteristics (FC), in different types of mills, i.e., pulp, paper and integrated mills, in Sweden from 2006 to 2015 indicate that correlations among the studied variables were different in different types of mills. This difference between types of mills seemed to originate partly from varying accessibility to production residue that could be used for energy. For all types of mills, variation of electricity prices did not correlate significantly with energy efficiency during the study period. The studied FC were firm's age, number of employees, number of companies in company group, net sales and profit for the year. Energy efficiency was more affected by the variables characterizing energy and production compared to the variables representing FC. This study also suggested presence of possible discrepancies between FC that were perceived as barriers to energy management towards energy efficiency, according to previous studies, and what was shown by the data combining variables representing energy use, production and FC.

Guiding industries to produce in an effective and environmentally sustainable manner has become a key issue for governments around the world. Over the past 15 years, series of regional and industrial development policies have been introduced by the Chinese government. This has influenced the geographical distribution and energy efficiency performance of China’s industries. This paper quantifies the influence of enterprises geographical distribution on energy efficiency improvement in the paper industry and aims at providing some helpful suggestions on industrial development to policy makers. The main results show that, firstly, the paper industry in eastern China shows obvious characteristic of agglomeration. The average location quotient is 1.2278. However, following the industrial and regional development policies, the characteristic of agglomeration is weakening. Secondly, only when agglomeration reaches a certain level (location quotient is above 0.5447) will industrial agglomeration positively impact on industrial energy efficiency improvement (a 1% increase in agglomeration will increase dynamic energy efficiency by at least 0.23%). Thirdly, the regional development policies carried out by the government slow the pace of energy efficiency improvement in China’s paper industry. The empirical results indicate that the government needs to consider regional characteristics and consciously guide industrial enterprises to concentrate in the dominant area.

Background: In spite of the continuous efforts and investments in the last decades, lignocellulosic ethanol is still not economically competitive with fossil fuels. Optimization is still required in different parts of the process. Namely, the cost effective usage of enzymes has been pursued by different strategies, one of them being recycling. Results: Cellulase recycling was analyzed on Recycled Paper Sludge (RPS) conversion into bioethanol under intensified conditions. Different cocktails were studied regarding thermostability, hydrolysis efficiency, distribution in the multiphasic system and recovery from solid. Celluclast showed inferior stability at higher temperatures (45-55 ºC), nevertheless its performance at moderate temperatures (40ºC) was slightly superior to other cocktails (ACCELLERASE®1500 and Cellic®CTec2). Celluclast distribution in the solid-liquid medium was also more favorable, enabling to recover 88 % of final activity at the end of the process. A Central Composite Design studied the influence of solids concentration and enzyme dosage on RPS conversion by Celluclast. Solids concentration showed a significant positive effect on glucose production, no major limitations being found from utilizing high amounts of solids under the studied conditions. Increasing enzyme loading from 20 to 30 FPU/ gcellulose had no significant effect on sugars production, suggesting that 22 % solids and 20 FPU/gcellulose are the best operational conditions towards an intensified process. Applying these, a system of multiple rounds of hydrolysis with enzyme recycling was implemented, allowing to maintain steady levels of enzyme activity with only 50 % of enzyme on each recycling stage. Additionally, interesting levels of solid conversion (70-81 %) were also achieved, leading to considerable improvements on glucose and ethanol production comparatively with the reports available so far (3.4 and 3.8 fold, respectively). Conclusions: Enzyme recycling viability depends on enzyme distribution between the solid and liquid phases at the end of hydrolysis, as well as enzymes thermostability. Both are critical features to be observed for a judicious choice of enzyme cocktail. This work demonstrates that enzyme recycling in intensified biomass degradation can be achieved through simple means. The process is possibly much more effective at larger scale, hence novel enzyme formulations favoring this possibility should be developed for industrial usage., This work had the fnancial support of the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/ BIO/04469/2013 unit, COMPETE 2020 (POCI-01-0145-FEDER-006684) and the MultiBiorefnery project (POCI-01-0145-FEDER-016403). Furthermore, FCT equally supported the Ph.D. grant to DG (SFRH/BD/88623/2012)., info:eu-repo/semantics/publishedVersion

Energy efficient cultivation is the major bottleneck for microalgal biomass production on a large scale and considered very difficult to attain at northern latitudes. In this study an unconventional method for industrial microalgae cultivation for bio-oil production using pulp and paper mill waste resources while harvesting only once a year was performed, mainly in order to investigate the energy efficiency of the process. Algae were cultivated for three months in 2014 in covered pond systems with access to flue gas and waste heat from the industry, and the biomass was recovered as thick sediment sludge after dewatering. The cultivation systems, designed to manage the waste resources, reached a promising photosynthetic efficiency of at most 1.1%, a net energy ratio (NER) of 0.25, and a projected year-round energy biomass yield per area 5.2 times higher than corresponding rapeseed production at the location. Thus, microalgae cultivation was, for the first time, proven energy efficient in a cold continental climate. Energy-rich indigenous communities quickly out-competed the oleaginous monocultures used for inoculation. The recovered biomass had higher heating values of 20–23 MJ kg− 1 and contained 14–19% oil dominated by C16 followed by C18 fatty acids. The cultivation season at 59°15′N, 14°18′E was projected to be efficient for 10 months and waste heat drying of the biomass is suggested for two winter months. The technique is proposed for carbon sequestering and energy storage in the form of microalgal sludge or dry matter for later conversion into biochemicals.

The purpose of this study is to investigate influence of calcination and cooling conditions on pozzolanic reactivity of waste paper sludge. Calcined paper sludge (CPS) is prepared by different temperatures of calcination, duration of calcination and cooling methods. Pozzolanic activity of CPS was investigated by using API (Assessed Pozzolanic Activity Index) and SAI (Strength Activity Index) in accordance with ASTM C618 -17 (KS L 5405) and consumption of Ca(OH)2 hydrate in mortars with CPS in detail, and compared to that of commercial fly ash (FA) and blast furnace slag (BFS) used in the concrete industry. Results revealed CPS produced from waste paper sludge had excellent pozzolanic activity compared with commercial pozzolanic admixtures such as FA or BFS. Their pozzolanic activity was most excellent in calcination temperature of 700 °C, calcination duration of 2 h and cooling method of water quenching. SAI (%) of mortar with CPS produced under optimal conditions was 96% at 28 days of age, and satisfied the quality of fly ash (Class F) as specified in ASTM C618 -17 (KS L 5405). There was linear relation between API (%) and SAI (%) of mortars with CPS, and the correlation coefficient was relatively good as 0.8 at 28 days of age. The API method is recommended as rapid and appropriate evaluation of the pozzolanic activity of the CPS.

This study aims to examine the economic and environmental benefits of recovered paper and potential contribution of the recovered paper to the Kingdom of Saudi Arabia (KSA) Vision 2030. The Vision 2030 is an inclusive development policy, recently launched, with the objectives to build the best future for the country. The Vision 2030 is based on three ambitious goals: making the country a vibrant society, a thriving economy and an ambitious nation. It is estimated that by 2030, 5.05 million ton of waste paper would be recovered in the country. About 11.3 billion SAR (US $3.01 billion) would be added to the country’s GDP and would create about 16,536 new jobs if the recovered paper industry is built in the country. Moreover, a net environmental benefit of 9.6 million crude barrel oil savings and 4.5 million ton of CO2 savings from GHG emissions could be achieved by 2030 only from the paper waste recovery in the country. The potential benefits of paper waste recycling in KSA highlight the needs of effective measures to optimize the economic and environmental opportunities inherited in the waste paper industry. These measures should focus on capitalizing the local waste paper processing industry, restrict the export of raw waste paper materials, and enhance the waste paper collection process and quantity.

Different heating processes were applied to pretreat the pulp and paper mill sludge to enhance the hydrolysis stage. Hot air oven, autoclave, microwave and water bath were used for comparison. Chemical analyses exposed that all the pretreatment methods have shown improvement in solubilisation of organic matter. Among the pretreatments studied, heat transfer through hot air (80 °C for 90 min) mode had the highest impact on sludge solubilisation. There was an increase in cellulose (P = 0.0096), acid soluble (P = 0.0053) and insoluble lignin (P = 0.0012), but decrease in hemicellulose (P = 0.0009) content after pretreatment. The XRD and FT-IR spectroscopic characterisation shows the development of aliphatic, unsaturated and carbonyl carbon functionalities in the pretreated samples at higher severities. FESEM picture also confirms the change in structure after pretreatment. Thus, pretreatments contribute to disruption of the lignocellulosic structure making the cellulose easily accessible to acidogenic microorganisms.