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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.

Industrialization and urbanization are the key drivers to threaten the environmental quality and natural resources. Traditionally, pulp and paper industry has been highly reliant on forest based resources for its escalation. Shortage of forest based raw materials, strict environmental regulations and policies have compelled the industry to seek for alternate raw materials for its production. Mills are now focusing on exploring the potential of different agro wastes such as cereal straws and bagasse etc. In present research, sugarcane trash, one of the most abundant agro residues in India, was investigated for its capability in pulping and bleaching. Chemical characterization of sugarcane trash showed that it contains 40.4% cellulose, 33.2% hemicelluloses, 17.4% lignin and 6.45% ash content with 2.76% silica. To cook sugarcane trash with soda pulping method, 14% alkali charge, 15 min time and 162 °C temperature was found to be optimum and pulp of kappa no. 19.8 was prepared that exhibited good strength properties. Bleaching of pulp was carried out using elemental chlorine (Cl2), hypochlorite and chlorine dioxide (ClO2) based sequences. Replacement of Cl2 with ClO2 has significant impact on strength properties and effluent characteristics. Oxygen delignification stage was incorporated prior to ClO2 that resulted in improved optical properties of pulp with noticeable reduction in wastewater load. This paper elaborates the need of using sugarcane trash in paper mills with environment friendly pulping and bleaching processes to combat with the problem of waste management, wastewater load reduction during bleaching and substitute for wood based raw materials in papermaking.

This paper examines the mechanical properties and durability of recycled aggregate concrete (RAC) containing 100% coarse recycled concrete aggregate (RCA) and industrial by-products. The by-products, including waste paper sludge ash (PSA), fly ash (FA), silica fume (SF), and metakaolin (MK) of different proportions (5%, 10%, 15%) in RAC, were used in two methods: replacement and addition methods. The use of by-products (mineral admixtures) to mitigate the low quality of RAC was demonstrated through experimental outcomes in this study. The addition of industrial by-products was presented as a promising alternative for the addition of more Portland cement in RAC to enhance RAC's quality. The results showed that the strength and durability of RAC containing mineral admixtures in the addition method were higher than the addition of more cement or the replacement method. Notably, PSA considerably improved the mechanical properties of RAC at an early age, and it substantially improved the resistance of RAC to acid and sulfate attacks. At 90 days, FA and MK improved mechanical properties of RAC greater than SF and PSA did. Among combinations, the proportions of by-products in RAC of 5% PSA, 10% SF, 15% MK and 15% FA can produce the highest performance of RAC with 100% coarse recycled concrete aggregate (RCA).

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.

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.

Black liquor, an industrial waste, also generally called spent liquor is a promising feedstock for production of bio-carbon due to its high lignin and energy contents. Mild processing conditions and sustainable resource utilization can drive commercial utilization of this industrial waste. A novel oxidative procedure using hydrogen peroxide as a green liquid oxidant at room temperature for processing of paper recycling neutral sulphite semi-chemical spent liquor was established and evaluations were carried out for its efficiency. Standard hydrothermal carbonization was carried out for comparing bio-carbon production qualitatively and quantitatively using the same spent liquor. The oxidation procedure was performed at room temperature using 5% of H2O2 followed by washing in diluted sulfuric acid (0.15 N) while hydrothermal carbonization was performed at 250 °C. The bio-carbon produced were similar in terms of ash percentage and ranged from 1.25 ± 0.05 to 1.48 ± 0.05% for oxidation method and from 1.11 ± 0.03 to 1.45 ± 0.04% for hydrothermal carbonization. The carbon contents for the oxidation method ranged from 60.54 to 61.50% and 66.81–67.31% for hydrothermal carbonization while higher heating values ranged from 25.32 to 26.11 MJ/kg and from 28.68 to 29.34 MJ/kg respectively. The mass yield ranged from 29.98 to 31.88% by the oxidation, while it was 15.02–16.08% by hydrothermal carbonization.

The global demand for bio-plastic particularly polyhydroxyalkanoate (PHA) have been increased in the last few decades as a substitute of petrochemical-based plastic. Utilization of waste paper, the primary constituent of municipal solid waste (MSW), as a carbon source for polyhydroxybutyrate (PHB) production is not only an alternative, environmental friendly route of waste management but also helps to valorize the waste. In this study, hydrogen peroxide pretreated waste paper saccharification has been optimized using central composite design (CCD). The maximum hydrolysis (88.18%) occurred at paper loading 5.0 g/L, agitation 242 rpm, working volume 20%, cellulase 49.82 U/g, β-glucosidase 20.9 U/g and hemicellulase 29.5 U/g. PHB synthesis and biomass accumulation by xylose-utilizing Burkholderia sacchari using waste paper hydrolysate were studied using different nitrogen sources and carbon to nitrogen (C/N) ratios. Maximum PHB and dry cell weight (DCW) occurred with ammonium sulfate and a C/N ratio of 20. The highest biomass (3.63 g/L), the maximum PHB accumulation (44.2%) and the maximum reducing sugar utilization (92.1%) were observed after 48 h of cultivation using diluted hydrolysate. The physicochemical properties of the extracted PHB were compatible with the standard PHB. Hence, the waste paper could be exploited as a renewable feedstock for the sustainable production of PHB.

The industrial solid waste generation and its stockpile disposal have major environmental consequences. These consequences could be minimized through the solid waste application as a raw material in other industries. The current study focusses on the utilization of lime sludge with boiler ash synthesized nanosilica for production of belite based clinker at relatively lower temperature. Lime sludge was also used in combination with fly ash and boiler ash to check the synthesis of compounds at varying temperatures. Nanosilica was synthesized from pretreated boiler ash through alkali treatment and acid precipitation. The synthesized nanosilica has been characterized for specific surface area, crystallinity, surface functional groups and size. Three different mixtures, containing lime sludge with nanosilica, fly ash, and boiler ash are fired at temperatures ranging from 900 °C to 1200 °C and characterized for the synthesis of belite. Conventionally, belite is synthesized above 1200 °C, whereas the combined application of lime sludge and nanosilica reduces the temperature of belite synthesis to 900 °C without pre calcination or addition of any chemical stabilizer. In the case of lime sludge and boiler ash blend, belite formation takes place at the higher temperature (1100–1200 °C). Anorthite synthesis takes place in case of lime sludge and fly ash blend, due to high percentage of alumina present in fly ash. Lime sludge and nanosilica based belite clinker are used to develop newer cementitious binder. Hydration and strength properties of developed binder proved worthy as building materials. This study will present alternatives for sustainable utilization of lime sludge, fly ash and boiler ash in construction.

Paper-based electronics offer a simple and cost-effective means to fabricate flexible devices. Here, we report an efficient pen-on-paper approach to construct metasurfaces on paper with silver units. Further, paper-based metasurfaces are employed to shield the electromagnetic interference which create new opportunities in turning waste paper into a solution for eliminating electromagnetic pollution. Experimental measurements and simulations show that waste paper-based metasurface manufactured in this way exhibits remarkable electromagnetic shielding properties with small thickness (thickness reduced more than 90% compared with that of traditional shielding materials), which makes it an ideal candidate for specific frequency electromagnetic filters. In addition, it can be readily extended to other regions of the electromagnetic spectrum, widened the shielding band by simply scaling the silver units' sizes and utilizing appropriate three-dimensional structures. Having taken performance into consideration, production is also taken into account. Paper-based shields offer both economic and energy benefits when considered on electronic printing, in addition, environment friendly nature and pliability of paper as well as simple fabrication procedure make paper-based metasurfaces promising candidates for the future ‘green’ electronics.

Waste paper, one of the major components of municipal and industrial wastes, has considerable potential as a low-cost inductive feedstock for enzyme production. In this study, four kinds of waste papers were used for simultaneous production of cellulase and xylanase by Trichoderma longiflorum. The highest FPase activities (3.21 IU/mL and 2.97 IU/mL) were achieved using waste office paper (WOP) and corrugated board (CB), respectively, followed by magazine paper (MP, 2.51 IU/mL) and tissue paper (TP, 2.34 IU/mL). The maximum β-glucosidase activities (0.51 IU/mL) and xylanase activities (382.59 IU/mL) were obtained from CB substrates, which were higher than that in the reported literature using waste paper. Correspondingly, the soluble protein concentrations and SDS-PAGE profiles from CB fermentation revealed that more enzymes were secreted during fermentation compared with other waste paper. Moreover, the structural features of different waste paper were characterized by using SEM and XRD technique and revealed that the structural variations were mainly caused by the raw wood sources and papermaking processes, and further affected the fermentation capacity. In addition, a higher β-glucosidase activity of 0.80 IU/mL were obtained from the mixed carbon source of CB and wheat bran (WB), which were significantly improved and increased by 56.86% when compared with the CB as single carbon source. This study confirmed that the waste paper without pretreatment could be efficiently utilized as an inductive feedstock for simultaneous production of cellulase and xylanase by T. longiflorum. Therefore, these findings obtained from this study will provide a more widely insight into investigating the low-cost inductive feedstock for enzyme production, which were of great benefit both for the economy and environment.

Papermaking enterprises are currently under both environmental pressure and economic pressure for sustainable development in China. Thus, the efficiency, effectiveness, and benefits of resource utilization need to be improved. High-consumption and high-pollution companies should manufacture paper using sustainable methods. This study highlights a resource value flow analysis from the circular economy perspective, developing an extension of material flow cost accounting and modifying it by accounting for environmental damage as well as economic benefits. With reference to the Plan-Do-Check-Act cycle, this specific case study was conducted to verify the comprehensive utility of resource value flow analysis by establishing decision-making prioritization according to the dualistic diagnosis of “internal resource loss–external environmental damage costs.” In general, applying a resource value flow analysis can both reduce resource consumption and minimize environmental damage, enhancing the sustainable development of a process industry with limited resources.

Straw pulp in China, which is the world's largest producer of this material, suffers from water and energy shortages during its entire life cycle. However, limited systematic studies have focused on these issues, and decision makers need be provided with improvement methods for the environmental performance. Thus, an impact-oriented energy and carbon coupled water footprint analysis was conducted in this study based on ISO standards. Results showed that the impact of energy consumption and carbon emissions exceeded that of water footprint. Carcinogens, non-carcinogens, and freshwater ecotoxicity also played effective roles in improving the environmental performance. Optimizing key indirect processes, including chemicals production, steam preparation, electricity generation, wood pulping, and fertilizer recovery, dominated the reduction in environmental burdens. Direct freshwater consumption and wastewater disposal played additional effective roles in controlling water footprint. The water network was thus optimized by a water pinch analysis to decrease the freshwater consumption and pollutant emissions by maximum values of 91.5% and 99.7% after optimization, respectively. Meanwhile, carbon dioxide, methane, chromium, arsenic, mercury, titanium, copper, strontium, total nitrogen, total phosphorus, BOD5, and COD were the main pollutants. Overall, the environmental impact can be further reduced by diminishing coal power ratio in national energy structure, adopting recovered steam, and considering multistage regeneration water network to cope with different water use demands.

Research has revealed the existence of an energy-efficiency gap – the difference between optimal and actual energy end-use, suggesting that energy efficiency can be improved. Energy management (EnM ...

Pulp and paper is considered to be the fourth most energy-intensive industry (EII) worldwide. However, as most of the CO2 emissions are of biomass origin, this sector has the potential to become a carbon-negative industry. This study proposes a new concept for conversion of the pulp and paper industry to carbon negative that relies on the inherent CO2 capture capability of the Kraft process. The techno-economic performance of the proposed carbon-negative system, based on calcium looping (CaL) retrofitted to a pulp and paper plant, was evaluated. The effect of CaL design specifications and cost assumptions on the thermodynamic and economic performance were evaluated. Under the initial design assumptions, the reference pulp and paper plant was shown to turn from electricity importer to electricity exporter with the cost of CO2 avoided equal to 39.0 €/tCO2. The parametric study showed that an increase in the fresh limestone make-up rate resulted in a linear increase of the specific primary energy consumption for CO2 avoided (SPECCA) and a reduction in the amount of electricity exported to the electric grid. This translates into an increase in the price of pulp and newsprint, and the cost of CO2 avoided. This study has also demonstrated that the pulp and paper industry has high potential to become carbon negative. It has been shown that carbon capture and storage would become economically viable in this industry if the negative CO2 emissions are recognised and a negative CO2 emissions credit of at least 41.8 €/tCO2 is implemented.

Paper production generates pulp and paper wastewater (PPW), and it is difficult to remove the high-level pollutants in PPW efficiently. Herein, an efficient industrial-scale pulp and paper wastewater treatment plant (PP-WWTP) that integrated physicochemical and biological processes is investigated and reported. This PP-WWTP treated 2.3 Mt of wastewater with 17,388 ± 1436 mg/L chemical oxygen demand (COD) annually. The PP-WWTP can effectively remove over 99.81% of the COD. In detail, the physical, anaerobic, aerobic and chemical steps accounted for 41.6%, 40.0%, 11.9%, and 6.5% of COD removal, respectively. The microbial communities of the bioreactors removed the pollutants efficiently and contained diverse microbes. Further metagenomic analyses of the bioreactors identified more than 90,000 genes/gene fragments encoding for carbohydrate-active enzymes (CAZys), demonstrating high lignocellulose degradation ability of the bioreactors at molecular level. The xylanase activity assay showed some lignocellulase in the bioreactors were functional. Recycling the residual heat from the PPW along with energy recovered from biological treatment of the PPW, in the form of biogas (20,000 m³/d), could generate more than 1.5 M USD benefits/y. The results of this study demonstrated that the integrated physicochemical and biological process for PPWW treatment could effectively remove pollutants while generating revenue.

To reduce energy use and achieve a low carbon production in pulp and paper industry (PPI), it is essential to improve energy efficiency in pulp and paper production. In this study, the energy savings from the PPI were estimated based on a techno-economic analysis by EAGER tool for PPI at the factory level. The structure and implement procedure were introduced initially. Two typical pulp and paper mills from China were determined to estimate the impact of selected energy efficiency technologies (EETs) on energy savings as the cases in the base year. One Factory (A) only produced paper products (i.e. corrugated paper and Kraft linerboard) while the other Factory (B) also produced market pulp besides sack paper. In totally 22 selected EETs were applied to assess their saving potential in Factory A, and 29 measures were applied in Factory B. The results show that 2290 TJ and 1179 TJ of final energy could be saved annually in Factory A and B, corresponding to reduction of 29.4% and 13.6% total energy consumption respectively for the case factories. The CO2 reduction potential was 32.3% for Factory A compared with that of 16.6% in Factory B. It suggests that the pulp and paper mills should encouraged to use this method estimating energy saving potential, and improve their energy efficiency with suggested measures in order to reduce energy consumption and related carbon emissions further in the coming years.

The study investigates for the first time the possibility of using carbon rich paper recovery sludge, and nitrogen rich meat processing industry waste as cultivation medium for the production of high value enzymes needed in the respective industries. The complex cellulose rich deinking sludge was able to support the growth of many industrially relevant enzyme producing microorganisms (Bacillus licheniformis, Candida cylindracea, Aspergillus oryzae, Trichoderma reesei) and of recombinant enzyme producers (Escherichia coli and Pichia pastoris). Further detailed studies with Trichoderma reesei as model organism demonstrated that the organism was able to grow optimally in the presence of 40gL-1 paper sludge as carbon source and 67.5 gL-1 pasteurised blood as nitrogen source substituted in Mandels medium. Under these conditions cellulase activities up to 28.1 nkat FPU were achieved. Anyhow, to achieve these results pretreatment of both waste streams is inevitable. In summary, this study provides the practical basis for a valorisation systems of paper industry waste to produce valuable enzymes to be used on-site in paper processing or for other purposes.

An enzyme cocktail (xylanase-15U, pectinase-2U, α-amylase-2.5U, protease-2U and lipase- 1.8U) from Bacillus halodurans was applied for the biobleaching of unbleached and ODL (oxygen delignification) agro based pulp in the R&D set up of Shreyans Paper Mills Ludhiana, India, upscaling from 5 g (at lab scale) to 100 g odp (oven dried pulp). Enzyme pre-treatment was carried out at temperature and pH optima of 65 °C and 9–9.5 for 90 min followed by reduced chemical treatment. In case of unbleached agro pulp, as compared to the total chemical bleaching in mill, enzyme cocktail pre-treatment reduced the chemical usage by 50% without compromising brightness and rather with increased tensile strength (23.55%), burst factor (20.3%) and tear factor (3.17%) and reduced kappa number (19.5%). In case of ODL pulp, enzyme cocktail pre-treatment reduced the chemical usage by 40%, yet increasing brightness (2.24%), tensile strength (20.96%), burst factor (5.1%) and tear factor (8.2%) with reduction in kappa number (4.54%). The enzyme cocktail thus can make the paper manufacturing process greener, safer, economical and eco-friendly and may replace big budget ODL technologies.

In accordance with global estimations, approx. 15 million tons of residues are yearly generated from paper and pulp industry, which are traditionally used as biofuels or just disposed in landfills. However, residues composition and laws in force urge producers to search for new waste management strategies. From another point of view, the construction industry uses more than 33% of total natural resources, worldwide which has led several governments to limit the use of natural raw materials for building. In particular, fired brick industry produces yearly approx. 1600 billion bricks which represents millions of tons of natural resources consumption. Therefore, the goal is to contribute to reduce the amount of used clay. Thus, this paper explores the mineral and technological properties of brick made by using different percentages of paper pulp residues and fired at 900 °C. Results indicate that by increasing the replacement ratio, blend requires larger amounts of water which leads to a proportional increasing of shrinkage during drying. In spite of mineral transformations are not influenced by paper pulp residue, the porosity is linearly increased which leads to reduce compressive strength and thermal conductivity up to 30% for 20% of replacement ratio, in both cases. Thus, it is concluded that series made by replacing up to 10% show compressive strength above 5 MPa, water absorption beyond 20% and toxicity indexes meet the mandatory requirements.

Fly ash and waste lime are solid wastes generated in pulp and paper mills. Due to high CaO contents, these secondary lime materials can be potentially utilized in the steelmaking process to partially replace primary lime. In this study, fly ash and waste lime from Swedish pulp and paper mills were made into briquettes and for the first time utilized as slag formers to replace primary lime in a pilot-scale Argon Oxygen Decarburization (AOD) stainless steelmaking process. The purpose was to evaluate how these CaO-containing materials could affect the AOD process and the steel quality. The results show that the S, P and CaO contents in the fly ash and waste lime are important concerns for metallurgical application. Firstly, due to lower CaO contents (61.5% CaO in fly ash and 90.6% CaO in waste lime versus 95.2% CaO in primary lime), utilization of these secondary lime materials could lead to higher slag amounts in the AOD converter. Secondly, due to higher S and P contents (0.40% S and 0.26% P2O5 in fly ash, 0.11% S and 0.75% P2O5 in waste lime versus 0.08% S and 0.01% P2O5 in primary lime), utilization of these secondary lime materials could increase the S and P contents in the steel. The S content in the steel can be controlled during the reduction and desulfurization stages; however, the P content in the steel increases with an increased use of these secondary lime materials. Thirdly, the metallurgical performance of fly ash and waste lime is as good as primary lime when considering the aspects that: (a) utilization of fly ash and waste lime doesn’t have negative effects on the decarburization stage nor on the reduction stage during the AOD process; and (b) fly ash and waste lime are as efficient desulfurization agents as primary lime. In future industrial applications, the alkali content and the variations of chemical compositions (especially with respect to S, P and CaO) of these secondary lime materials need to be carefully controlled to ensure a sound metallurgical operation.

Recovered paper is one of the major raw material for recycled papermaking industry. In China, the domestic recovered paper recycling system is incomplete and the amount of recyclable recovered paper cannot satisfy the papermaking demand. Therefore, the recycled papermaking industry is extremely dependent on imported recovered paper as their raw fiber source. In 2018, Chinese government announced a ban on unsorted recovered paper and tightened the import quota for recovered paper, which resulted in a dramatic drop in the importing amount of recovered paper. It is an urgent issue to explore alternative production routes that are more economical and environmentally friendly. Herein, life cycle cost assessment is used to compare and analyze the recycled papermaking industry based domestic recovered paper and three alternatives (including straw, imported deinked pulp and imported wood pulp) as the raw materials. The results show that the life cycle cost of domestic recycled paper based recovered papermaking is significantly lower than the other three alternatives, whereas its external cost is higher than that of the production routes based on the imported deinked pulp and imported wood pulp. With the increasing price of the domestic recovered paper, imported deinked pulp is the trend of recycled papermaking industry in China.

Each day a large amount of toilet paper (TP) is flushed into sewers. Recovering the disintegrated fibers from wastewater can reduce the treatment cost and the recovered fibers have some value-added applications. However, typical preliminary treatment units are inefficient at capturing these small-sized fibers. Although sieving can recover them effectively, it is rarely used due to high costs. Results from this study suggested that redesigning TP to disintegrate less in water can be a more cost-effective approach. Here, we evaluated the disintegration of TP in sewers and fiber recovery through screening, sieving, and sedimentation. We found that the highly disintegrated TP are significantly more challenging to retrieve using conventional approaches. Fine screens with an opening size of 3 mm recovered only 45.7% of the TP fibers. Sieves with 0.1–1 mm openings retrieved up to 94.5% of the TP fibers but were very prone to clogging. Further, the fiber recovery by preliminary treatment was heavily impacted by the TP disintegration degree, which was found to be predominantly affected by the flow motion, wetting time, and inherent stability of TP. A life-cycle cost (LCC) analysis showed that redesigning TP (i.e., designing it to disintegrate into fragments rather than separated fibers) could significantly promote fiber recovery with the existing infrastructures. The 15-y operational costs could be reduced by up to 46% by using redesigned TP. This work presents a promising way to facilitate TP fiber recovery from wastewater at lower cost; pilot and full-scale surveys must be conducted to evaluate feasibility.

Disposable paper cups comprise typical single-use plastic items, as they are lined internally with a thin plastic coating for waterproofing. They are consumed at a staggering rate worldwide, with the UK alone consuming around 7 million cups daily, thus annually producing around 30,000 tonnes of paper cup waste. Contrary to popular belief, less than 1 in 400 paper cups is currently recycled in the UK, which is in stark contrast to the waste hierarchy and the European Commission’s ambitious Circular Economy Action Plan. Paper cups typically end up in landfill sites or even improperly disposed of, contributing to (micro)plastic waste and potentially polluting the world’s oceans. The implications of the latter are not fully known yet and cannot be quantified by existing life cycle impact assessment methods. By employing the life cycle assessment methodology, UK’s annual carbon footprint from paper cup consumption was found to be 75 kt of carbon dioxide equivalents, which is similar to that of manufacturing 11,500 mid-size passenger cars. Globally, their environmental footprint was found to be comparable to that of some 1.5 M average European inhabitants, indicating the nature and extent of the single-use plastics problem, which paper cups are just a typical example of. Paper cup recycling could reduce this environmental footprint by up to 40%, whereas switching to reusable cups appears to be more environmentally sustainable, achieving a threefold reduction in carbon emissions, which at global scale is more than twice Malta’s annual carbon footprint. Results indicate that consumerism along with small daily choices, such as using reusable cups or bags instead of their disposable counterparts, could play a huge role in climate change. At policy level, no concrete measures to curb the superfluous consumption of paper cups, as well as of other single-use plastic items that are becoming increasingly ubiquitous, have materialised. Furthermore, it appears that decision- and policy-makers tend to step in to curtail wasteful and polluting practices only when environmental problems have started to generate widespread concern, instead of undertaking preventative policy measures.

The pulp and paper industry traditionally generates large amounts of wastes at different stages of its production process, such as primary sludge that is extremely wet. The aim of this research is to evaluate a new process methodology aiming the incorporation of primary pulp and paper industry sludge waste, still in its liquid state, into cement and lime-based mortars. This procedure was compared with the incorporation of the waste in its dry state, which results from the traditional beneficiation process based on powder drying. Comparison was performed in terms of technological, durability and environmental performance of both wastes (liquid and dry) incorporated mortars, as well as with reference control mortar without incorporation. Two news models of liquid waste processing, for mortars incorporation, called thin and coarse liquid, were developed in order to evaluate technological parameters such as: consistency, entrained air, water retention, mass density, capillary absorption and mechanical strength. These parameters allow the characterization of durability, life cycle assessment and environmental conditions. Technological properties showed satisfactory results in mortars performance when waste was used as a thin liquid with nominal content (optimal mixture) similar to the reference composition. The air content of the mortar was 12% and the water retention 96.8%. In the hardened state, the optimal mixture had a mass density of 1.76 g/cm3, a capillary coefficient of 20.73 g/dm2.min1/2 and mechanical resistance to compression of 3.7 MPa and to flexion of 1.1 MPa, all results meet the limits of the literature for application in construction. It was found that the beneficiation process, which produces the thin liquid is the most efficient for the incorporation of waste into mortars when compared to the dry method. Indeed, the thin liquid waste incorporated mortars showed improved technological, durability and environmental properties.

Green liquor dregs and slaker grits are pulp and paper mill residues usually landfilled. Whit high calcium carbonate content, its use as alternative raw materials in traditional ceramic products becomes an interesting study field. In order to evaluate its incorporation potential, the residues characterization with diverse approaches was performed and for the first time reunited exploring this eco-friendly intent. Green liquor dregs and slaker grits were characterized by its chemical and mineralogical composition (XRF, XRD, FT-IR); physical and morphological characteristics (particle size, BET surface area, density, SEM) and thermal properties (TGA). Chemical and mineralogical analysis reveals the high calcium carbonate content in calcite form especially on slaker grits, that has less inorganic and organic contaminants than green liquor dregs. Smaller irregular-shaped particles and bigger surface area was found on this last residue, comparing with slaker grits. The thermal analysis indicated a lower calcite decomposition for green liquor dregs (720 °C), while this event on slaker grits occurred 40 °C above (760 °C). Thus, it was observed the residues behavior and characteristics are much alike calcium carbonate itself, especially slaker grits, considering its composition, morphology and thermal events. As conclusion, the potentiality uses of green liquor dregs and slaker grits as alternative raw materials on ceramic products was revealed. Being able to incorporate clay, concrete, glasses and great majority of other ceramic products, these residues use will generate excellent benefit-cost ratio to industries and environment.

The objective of this work was to examine opportunities for reducing the overall cost of lignocellulose hydrolysis to fermentable sugars. Primary sludge (PS), a negative cost lignocellulosic feedstock, was hydrolyzed sludge using a commercial cellulase preparation (Cellic® CTec2) in presence of non-ionic surfactants. Polyethylene glycol (PEG) 4000 facilitated the highest hydrolysis yield of 74.4% which represented a 2-fold increase over the control without surfactant. Response surface methodological analysis at four variables (hydrolysis time, solids, enzyme, and surfactant loadings) revealed that enzymatic hydrolysis was significantly enhanced by the interactive effect of all factors with solids and enzyme loadings as the most significant parameters (p

In order to achieve an effective re-utilization of pulp and paper industry waste (PIW), PIW was recycled and used as a filler to prepare green-composites based on linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and ultrahigh molecular weight polyethylene (UHMWPE) through an extrusion and injection molding in this study. The resultant green-composites were characterized by infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetry, tension, dynamic mechanical analysis, and micro mechanism. The results showed that the addition of PIW promoted crystallization and improved the thermal stability of LLDPE, HDPE, and UHMWPE. Moreover, the tensile properties of LLDPE, HDPE, and UHMWPE were significantly improved as a result of PIW addition. The best tensile strength of 26.73 MPa and Young’s modulus of 1.82 GPa were obtained in PIW/HDPE composites. The dynamic mechanical analysis revealed that the addition of PIW increased the rigidity and elasticity of LLDPE, HDPE, and UHMWPE. The utilization of hazardous PIW in this study not only avoids secondary pollution but also generates green-composites with better thermal and mechanical properties.

In a circular economy, extended producer responsibility (EPR) is a regulatory approach that accounts for all environmental costs associated with a product throughout its life cycle. When considering the EPR, the regulator must (1) design an integrated framework for different stakeholders and (2) provide effective policies to create financial incentives to accelerate the circular system. Recycling funds and subsidies are the most prominent financial strategies that can either encourage or curtail the flows of recycled products. In Indonesia, a few companies provided recycling bonus s to their customers as incentives to increase the recycling rate. However, the recycling rate was not as effective as expected by the enterprise because recycling was practiced by a limited number of companies, rendering it economically unviable. The enterprises hope the government could develop a recycling fund system. In order to develop the recycling fund system, a system dynamic model was proposed and simulated to optimize the recycling funds and subsidies based on decentralized reverse supply chains. Although it is not a novelty model; however, the research show a very significant results for the government in Indonesia. This enabled a more precise, well-planned, and sustainable decision-making process for the EPR. In addition, by utilizing the system dynamic model with different scenarios in a real case study (aseptic paper packaging waste), we found that the capacity of the recycler could become the reference for the funds to be paid by the importer-producer group, wherein the recycling rate will increase with an increase in the recycling fund.

The forest sector is vital in Europe, providing economic and social benefits to communities. However, this sector is also responsible for some environmental impacts, and it is crucial to ensure that these impacts do not outweigh the benefits described. For this reason, this paper proposes an environmental and economic assessment of three forest wood products – uncoated woodfree paper, natural cork stoppers, and particle boards. The life cycles of these products were modeled using foreground data and a life cycle assessment was conducted to determine the environmental impacts associated with these three life cycles. For the economic assessment, the net present value method was adopted. From the results, it is possible to conclude that the utilization of 1 ha of forest land for 100 years to plant Eucalyptus globulus used in the production of uncoated woodfree paper generates the least environmental impact per euro. A sensitivity analysis was conducted to determine the reliability of the results achieved given the uncertainty associated with the data used to model the three life cycles. The same critical impact categories and the same critical life cycle stage (raw materials’ extraction) were identified for the three systems under study. Given these similarities, an effort must be made by the forest sector to reduce the impacts of these categories and this life cycle stage. To assist on this task, a set of generic and industry-specific recommendations is provided for companies operating in the forest sector.

Developing monitoring system for paper industrial wastewater treatment system is an important route for wastewater reuse and recycling from wastewater, which are regarded as effective way for cleaner production. A novel hybrid deep leaning CLSTMA model, which based on sequential fusion convolutional neural network (CNN), long short term memory (LSTM) and attention mechanism (AM), was developed to monitor the water quality in a full-scale paper industrial wastewater treatment system for energy conservation and emissions reduction. The hybrid CLSTMA model for predicting water quality of paper industrial wastewater treatment system was divided into three steps: spatial information fusion by using CNN module, temporal information fusion by using LSTM module and variable weighted calculation by using AM module. Compare with other models (CNN, LSTM and CLSTM models), RMSE of CLSTMA model for the effluent chemical oxygen demand (CODeff) reduced by 23.3–31.55%, MAE of CLSTMA model reduced by 38.89–74.50%, R of CLSTMA model increased by 8.29–11.86%. For the effluent suspended solids (SSeff), compared with CNN and LSTM models, RMSE of CLSTMA model reduced by 10.26% and 9.92%, MAE of CLSTMA model reduced by 5.37% and 3.44%, R of CLSTMA model increased by 15.13% and 37.21%, respectively. While, R of CLSTMA was consistent with CLSTM model, but RMSE and MAE of CLSTMA model reduced by 16.07% and 7.49% than the CLSTM model. Simulation results demonstrate that the proposed CLSTMA model has a great potential in monitoring paper industrial wastewater treatment system for cleaner production.

Biobased and biodegradable polymers are a promising solution for agricultural plastics problems, especially for pollution and toxic residue from disposed non-degradable plastic mulch films. Application of biobased and biodegradable mulch films has been hindered by poor mechanical properties and higher cost than conventional plastic mulch film (polyethylene and poly (vinyl chloride)). This work explores the performance of multi-layer fertilizer-infused mulch papers fabricated via blade coating and melt compression molding with biodegradable poly (butylene succinate) (PBS), poly (hexamethylene succinate) (PHS), and their copolyesters. The water absorption, tear propagation properties, enzymatic degradation, and fertilizer release behavior of these multi-layer constructions are characterized. The influence of processing methodology on the coating performance is also discussed. It was found that a polymer concentration of 90 mg/ml in the blade coating process increased the coating thickness to about 30 μm, which slowed water absorption; however, the composition ratio of PBHS polymer coatings had little effect on water absorption. The coatings improved the tear propagation resistance up to 3 N (comparable with that of PE mulch film, 1.6 N) and biodegradation resistance of MP in soil. In this work, PHS coated MP provide an optimal strategy for the dual functions of mulching and fertilizer controlled release, as demonstrated by the barrier properties, degradation rate and mechanical properties. Plant growth trials demonstrated improved fertilizer utilization from slow-release coated papers, as shown by acceleration of the blossom and root growth.

Microbial fuel cell (MFC) is considered to be a sustainable technology for cellulosic waste treatment and energy recovery; however, studies on cellulose-degrading exoelectrogens are scarce. Giant panda gut microbiota may provide potential cellulose-degrading exoelectrogens due to consumption of high-fiber diet. In this study, strain LZ-P1 isolated from giant panda gut simultaneously showed cellulose-degrading and electricity-generating characteristics. 16S rRNA gene sequence revealed 99% homology with Cellulomonas iranensis. Results showed that the strain generated 1.08 U/mL endoglucanase and 180 mV electricity when cellulose was used as the sole carbon source. Genome sequence confirmed that strain LZ-P1 possessed complete cellulose degradation and extracellular electron transfer pathways. Proteomic analysis further confirmed that the enzymes involved in cellulose-degradation and extracellular electron transport were remarkably up-regulated, including endoglucanases, riboflavin biosynthesis protein, and cytochrome C oxidase. When strain LZ-P1 was applied to MFC-mediated paper recycling wastewater treatment, a maximum power density of 44.05 mW/m2 and 8.72% coulombic efficiency were recovered in 72 h. Therefore, strain LZ-P1 would be a potential candidate for cellulosic waste management and energy recovery.

Generation of fines and ultra-fines is a concept that mining and metallurgical sectors can never shy away since the beginning of coal exploration. These coal fines and ultra-fines are what coal mines regarded as waste material without economic value until the present moment. Poor technologies in the past led to stockpiling of large quantities of fines and ultra-fines. Increase in mechanization in the coal mining industry has also led to the generation of large quantities of coal fines and ultra-fines. Several techniques in the mineral processing sector have been explored to beneficiate the coal fines and ultra-fines. The explored beneficiating technologies include enhanced gravity separation, oil agglomeration, flotation, flocculation, spirals, water only cyclone and dense medium cyclone. These beneficiating technologies have their own limitations when treating fine and ultrafine coal. Major limitations were operation cost and separation efficiency. However, many researchers have improved these beneficiation technologies in terms of cost and separation efficiencies producing clean coal product that meet the end user product specifications. This paper reviews recent developments in beneficiation technologies of coal fines and coal ultra-fines.

Recycling wastewater of the pulping and paper-making industry are widely considered for clean production, which heavily rely on the timely and accurate monitoring in paper-making wastewater treatment processes. A novel predicting model based on genetic-deep belief network algorithm was proposed to improve the predictive accuracy and reliability for process monitoring. Considering the deep belief networks (DBN) as a deep learning model is aiming to describe the relationship among variables in a complex process modeling, genetic algorithm (GA) was employed to reduce the input variables dimensionality, simplify the network structure and overcome the dynamic characteristic difficulties of process data in monitoring. Compared with DBN and back propagation neural network (BPNN), the GA-DBN effectively achieved a better predictive accuracy than other tests models in complex wastewater treatment processes. The value of the coefficient of determination of GA-DBN model is increased by 1.71–1.86% and 5.21–9.32%, respectively. The GA-DBN model can be structured with fewer variables or samples to describe the complex paper-making wastewater treatment process, obtaining the better model performance and predictive accuracy.

Due to production technologies such as blasting, transportation, and loading, large quantities of dust are produced in surface mines. This dust not only pollutes the environment but also restricts the development of coal mining enterprises. This work aims to use waste paper as raw material for the efficient extraction of cellulose, in which waste materials can be converted to useable materials. This work can broaden the sources of raw materials and provide new methods for the efficient preparation of dust suppressants. As a matrix, sodium carboxymethyl cellulose is a novel crust-dust suppressant that is synthesized by graft copolymerization with polyvinylalcohol and N-vinylpyrrolidone in this study. The results of experiments revealed the high purity of sodium carboxymethylcellulose prepared in flotation for 20 min, the degree of substitution DS > 0.8, and the viscosity of 2% aqueous solution>300 mPa s, which can satisfy the requirements of the experiments. The microscopic reaction and structure of the product are analyzed by infrared spectrometry, scanning electron microscopy and thermogravimetry, and the microscopic mechanism of a crust-dust suppressant is investigated. The reaction process and structural characteristics of the product were analyzed by infrared spectroscopy and scanning electron microscopy, and the product reaction process and final structure were deduced. Thermogravimetric experiments showed that the product had strong thermal stability and ensured the performance of the product during use. This paper reveals the combination of dust suppressants and coal via molecular dynamics simulation. The product performance experiments show that the product has a high shell strength of 98 HA, satisfactory freeze-thaw resistance and high temperature resistance, permeability higher than 15 mm/min, and dust suppression rate of approximately 88% when the wind speed reaches 15 m*s−1 and it can degrade without pollution. In general, the product can effectively suppress coal dust and other forms of dust.

Remediation of contaminated soil can be performed by using various techniques, which must be adequately tailored for each specific case. The aim of this research is to critically evaluate the potential use of red mud and paper ash and a combination of the two as immobilization additives for the remediation of contaminated soil from one of the most polluted sites in Slovenia. The proposed procedure involves the preparation of geotechnical composites made from contaminated soil and mixed with 25 wt% of immobilization additives and an optimal quantity of water to achieve consistency, at which maximum compaction according to the Proctor Compaction Test procedure can be achieved. The results reveal a positive, time-dependent trend for the immobilization of potentially toxic elements in the composite with paper ash, because of the formation of the new hydration products with potentially toxic elements. In a composite containing only red mud, potentially toxic elements were immobilized by sorption mechanisms with no general time-dependent trends. The composite with a combination of additives demonstrates the remediation characteristics of both red mud and paper ash. Using this approach excavated contaminated soil, red mud and paper ash can be successfully recycled in the proposed composites, which can be beneficially used in situ for rehabilitation of contaminated sites. Nevertheless, mobilization of some potentially toxic elements at high pHs may represent a limiting factor and has to be taken into the consideration when a combination of red mud and paper ash is used as immobilization additive.

Indonesia’s internationally- and domestically-significant pulp and paper industries source their feedstock from tree plantations. A suite of regulatory (Indonesian Sustainable Production Forest Management Certification and Timber Legality Verification) and market instruments (forest certification) have been introduced to promote sustainability and legality of production from tree plantations, and some producers have also adopted other voluntary sustainability measures. This study investigates sustainability and legality compliance by actors in an Indonesian pulp and paper value chain as a case study of environmental innovation. Results are based on primary fieldwork along segments of the value chain, and analysis of audit reports and other publicly-available information. The value chain sources fibrewood from tree plantation concessions and pallet wood from a variety of suppliers. Audit reports suggest high levels of compliance with sustainability and legality requirements, but our research suggests that these reports might not reflect some area of poor performance and non-compliance. We identify weaknesses in the design of regulatory systems, and in auditing and monitoring processes, as the principal reasons for these deficiencies. Drawing on relevant theory and on practice elsewhere, we suggest that compliance and sustainability can be improved by addressing key areas of regulatory silence, by shifting auditing to be more performance-than paper-based, by strengthening independent monitoring from civil society, by increasing the frequency of witness auditing from the National Accreditation Board, and by fostering synergies between regulatory instruments and voluntary forest certification. These changes would improve the effectiveness of regulatory and voluntary instruments to promote cleaner production in Indonesian pulp and paper value chains.

In this study, we developed and demonstrated an integrated closed eco-system for pollution reduction and prevention in rice-paper producing and livestock farms in a small-scale craft village which is located in a dry region of Vietnam with a lack of available surface water sources. The system is developed on the basis of material and energy exchange potentials between the wastewater and exhaust gas flows, and the use of available firewood ash as material for absorption. Two operation modes were presented aiming at a complete treatment of wastewater and exhaust gases as required by the Vietnamese national standards, and the recovery of valuable components in the system (N, P) for obtaining value-added products (such as fertilizer, irrigation water, etc.). In addition, the maximization of potentials on existing natural conditions at the local family, the avoidance of chemicals used in the system etc. have also helped to lower the investment and operation costs of the treatment facilities. The application of this system also contributes to the “greening” of the rice production chain in the Mekong Delta, Vietnam and is an example for a local closed cycle economy. Several public activities have also been conducted at the demonstration site (at the local family) with the purpose of maintaining and multiplying the system's effectiveness among the local public community.

The pollution of water resource and shortage of clean water have become increasingly severe, developing an urgent demand of reliable, efficient yet low-cost material for everyday water purification. In the present work, a superhydrophobic paper tissue-based SiO2/PDMS composite has been prepared for both oil absorption and water-in-oil emulsion separation. The fabrication process is quite simple since it takes the full advantage of tissue that has naturally strong capillary force of which allows the material to absorb oil from water much more rapidly and completely (>99.9%) even under harsh conditions. The study has shown the novel material is exceptionally efficient in separating water-in-oil emulsion under gravity but no need of extraneous pressure. A variety of emulsions has been proven with high flux (>2,000 L m−2 h−1) and high separation efficiency (>99.4%). It is believed that this study has proposed a highly reliable and efficient, low cost strategy in both oil absorption and water purification, which shed light on water treatment of both civil use and industry.

Due to rapid deforestation, the paper industry is facing problems like shortage of forest based raw materials, cost increment and negative effects on the environment including increasing air, water and soil pollution. In India, agro residues utilized in stubble burning could be used as a sustainable fiber resource for papermaking, but the paper made from these possesses poor strength properties. Considering the multiple advantages of using agro residues and weak strength properties of the paper made from these, this study was conducted. The effect of blending hardwood pulp and agro pulp with cationic starch or chitosan at wet-end of papermaking with and without subsequent surface sizing using oxidized starch was explored. As a wet-end additive, chitosan dose of 0.5 kg/t was more promising than cationic starch dose of 5 kg/t with all pulps. Paper was produced from 85% agro and 15% hardwood pulp and 0.5 kg/t of chitosan at wet-end after surface sizing with oxidized starch. It improved the tear index, Taber stiffness, double fold and air permeance by 2.7%, 6.5%, 170%, and 300%, respectively with 18.4% decrease in Cobb60 as compared to paper made with 100% hardwood pulp. FTIR analysis was further done to evaluate the effect on crystallinity ratio and energy changes in hydrogen bonds in the papers of differently blended pulps after surface sizing. The study signifies the enhancement in strength and surface properties of paper made using agro pulp after addition of biopolymers at wet-end with and without surface sizing.

Waste generation from groundnut and sugarcane industries are at high alarming rate due to their disposal constraint. These wastes are currently used as a raw material for the production of compost, fuel, alcohol, and paper. Cellulose and its derivatives are being used in many industries like paper, pharmaceutical, and energy owing to its physicochemical properties. Application of cellulose in the leather industry uses cellulose derivatives as finishing chemicals such as nitrocellulose, ethyl cellulose. In the current study, an attempt has been made to find the application of cellulose from groundnut husk and sugarcane bagasse as an auxiliary chemical in leather finishing. Cellulose is extracted from wastes by modified acid hydrolysis method to enhance the yield. Extracted cellulose has been characterized and compared with commercial cellulose sample. From the characterization studies, it confirms that extracted cellulose matched with commercial samples. Extracted cellulose used in leather finishing as an ingredient to upgrade the low-quality leathers, which primarily have grain damages. Cellulose with different concentration of plasticizer has been used in the base coat along with binders and pigments. Finished leathers have been characterized to understand the physical characteristics. From the various analysis, it ascertains that the cellulose has imparted fullness to the finished leather without impacting the aesthetic property. The study provides a better utilization of sugarcane bagasse and groundnut husk wastes in leather industry leading to effective waste management prototype.

[EN] Current wastewater treatment plants (WWTPs) paradigm is moving towards the so-called water resource recovery facilities in which sewage is considered a source of valuable resources. In particular, urban WWTPs are crucial systems to enhance phosphorus (P) recycling. This paper evaluates the implementation of a P-recovery system in Calahorra WWTP combining the operation of a new sludge line configuration coupled to a struvite crystallisation reactor at demonstration-scale. This new configuration consisted in the elutriation in the gravity thickener of the mixed sludge contained in the mixing chamber in order to reduce the phosphate load to the anaerobic digestion. The results indicated that the P available in the primary sludge overflow was nearly five times more than the obtained for the conventional configuration (1.88 vs. 0.39 gP/kg sludge treated), and the uncontrolled P precipitation inside the anaerobic digester was reduced by 43%. Regarding the total P entering the WWTP, 19% of the total P could be recovered with the new configuration proposed in comparison with 9% in the previous conventional configuration. The average recovery efficiency in the crystallisation plant was 86.9 0.4%, yielding a struvite recovery of 8.0 +/- 0.6 kg/d (0.67 +/- 0.04 kg/m(3) fed to the crystalliser). The potential struvite production with the new configuration would be around 41 kg/d (15 t/y) crystallising the thickener supernatant which could be increased up to around 103 kg/d (38 t/y) treating all the P enriched streams (thickener supernatant and centrate streams). The paper demonstrates that WWTPs can contribute to reduce P scarcity, resulting in environmental and economic benefits. (C) 2019 Elsevier Ltd. All rights reserved., This work was co-financed by the European Financial Instrument for the Environment (LIFE +) as part of the PHORWater Project (LIFE12 ENV/ES/000441). The authors also like to acknowledge the support received from Consorcio de Aguas y Residuos de La Rioja and from EDAR del Cidacos (Calahorra).

This paper reviews various aspects of the enzymatic transesterification method to convert used cooking oil to biodiesel. The goal of this paper is to provide a thorough overview from general biodiesel production processes, reaction conditions, challenges, and solutions for higher biodiesel production yield through introducing various microorganisms that are capable of producing the enzymes required to convert used cooking oil into biodiesel. The characteristics, composition, and advantages of the used cooking oil, as feedstock for biodiesel, is also discussed. In addition, the existing transesterification methods including homogeneous alkali-catalyzed, homogeneous acid-catalyzed, non-catalytic reaction under super-critical conditions, and enzyme-catalyzed reactions are explained. Furthermore, the advantages of the enzymatic method over other methods, and the enzymes, which are the key elements of such reactions, are discussed. Lipases are the most promising enzymes currently known for biodiesel conversion. The physiological and physical properties of microbial lipases, the catalytic mechanisms of the enzymes, various methods of enzyme immobilization such as adsorption, covalent and affinity binding, entrapment, and the whole-cell immobilization are also reviewed. At the end, three case studies demonstrating unique and efficient enzymatic transesterification approaches are presented.

The research on the preparation of activated carbon co-activated by hydrothermal carbonization and pyrolysis was uncommon and less experiments used ultrasonic assisted impregnation. The synergistic effect of two catalysts had certain research value. There are still just a few studies on the performance prediction of activated carbon. In this paper, wheat straw, corn straw and sorghum straw were used as the raw materials. ZnCl2 and H3PO4 were used as the catalysts for the synergetic catalysis. Hydrothermal carbonization combined with pyrolysis was used to co-activate with the ultrasonic auxiliary impregnation method in order to prepare straw activated carbon. The straw activated carbon was characterized by different means and the principle of the method was analyzed. Then the performance prediction models of straw pyrolytic activated carbon using methylene blue number and iodine number as the main evaluation index based on Linear Regression, Support Vector Regression, Random Forest Regression were proposed and compared. The results indicated the three kinds of straw showed similar characteristics in the preparation of straw pyrolytic activated carbon whose specific surface area reached 1258.3927 m2/g, 1101.8430 m2/g and 1060.9723 m2/g respectively. The Random Forest Regression model was the most suitable. The n_estimators was set to 10. The evaluation indexes of the model were all good. It demonstrated the three kinds of straw were highly efficient precursor for the preparation of activated carbon used to remove dyes from wastewater. The preparation method in this paper combines the advantages of physical and chemical activation. The prediction model will accelerate the utilization of straw resources, realize the controllable and clean preparation of straw activated carbon and reduce environmental pollution.

This study uses municipal sewage sludge (MSS) as a fertilizer for cultivating Pennisetum hybridum (hybrid Giant Napier grass). The effects of the MSS treatment on the chemical composition of Pennisetum hybridum and on the properties of paper made from its pulp were investigated. The study found that the holocellulose content of Pennisetum hybridum exceeded 72% and the fiber length reached 0.83 mm for one-year-old MSS treated plants. The tensile index of paper made from Napier grass fiber increased by 194% after beating. SEM observation revealed that the Pennisetum hybridum fiber bonded more tightly after beating. The content of carboxylic acid groups was similar in the fibers of 3-month-old and 1-year-old hybrid Giant Napier plants, and higher than that for 1.5-year-old plants. The present research demonstrates that Pennisetum hybridum fiber is suitable for pulping and paper-making after fertilizing treatment of the plants with MSS, which provides new ways for MSS utilization.

Biodiesel is considered as an alternative for petroleum fuels. Hence, identifying efficient biomass for biodiesel production is necessary to meet the demand. This study reports the optimum conditions of Sterculia foetida oil for biodiesel production and its engine performance, emission and combustion analysis. Gas Chromatography-Mass Spectrometry revealed the dominance of fatty acids in the order of sterculic acid (32%) > palmitic acid (15.88%) > oleic (10%) > linolenic (9.95%) > malvalic acid (9%) respectively. Oil extracted from the seeds of Sterculia foetida were purified by the degumming process to remove the unwanted impurities present in the oil. Box-Benhken design was used for optimizing transesterification process. A Maximum biodiesel yield of 90.2% was obtained at a temperature of 55 °C, catalyst concentration 1.5%, Oil to methanol ratio 1:12, agitation speed 900 rpm. ANN model was also utilized for the prediction of biodiesel yield using feed-forward backpropagation exhibited significant correlation (R2 - 0.9) with experimental results. Biodiesel blends and their properties were also analysed. Carbon monoxide and hydrocarbon emission were found to be low with the observation of increased nitrogen oxide emission. D90STB10 and D80STB20 was showing better performance and also lesser emission ompared to the conventional fuel.Combustion analysis of Sterculia foetida biodiesel (STB) and biodiesel blends (D90STB10, D80STB20, D70STB30, D60STB40 and STB100) for the various load at constant speed were analysed. Cylinder gas pressure, cumulative heat release rate, heat release rate, mass fraction burnt and mean gas temperature were discussed in the current paper.

Globally, the processing of milk and dairy products leads to huge volumes of dairy processing wastewater treated sludge. Currently, there are knowledge gaps relating to the volumes generated and the nutrient and metal contents of these sludges. This lack of knowledge prevents the dairy processing industry from making informed pre and post waste generation decisions. Using Ireland as a case study volumes generated are estimated (2012–2017) and a two year seasonal database (2016–2018) across four sludge types (bio-chemically treated activated sludge; lime treated dissolved air flotation processing sludge; a combined treatment sludge and anaerobically digested sludge) utilising samples from nine dairy processing plants was created. Results show that dairy processing sludge increased by 39% in the period up to 126,718 tonnes (wet weight). Database results showed that nutrient contents did not vary seasonally but varied significantly across sludge type and processing plants. The median values (g kg−1 dry weight) for N:P:K for the four sludge types were N: 57.2, 19.5, 46 and 70.4, P: 36.8, 65.9, 20 and 14.6, and K: 7.2, 3.9, 2.9 and 6.1, respectively. Heavy metal concentrations across all samples were significantly lower than those regulated by the European Union for controlling metals accumulation in agricultural land due to sludge recycling. The characterization profile presented in this paper serves as a national and international reference database for future investigations that focus on the valorisation of dairy processing sludge.

This paper investigates the production of hydrogen (H2) and methane (CH4) from palm oil mill effluent (POME) using an integrated approach of thermophilic continuous stirred tank reactor (CSTR) and mesophilic microbial electrolysis cell (MECs). CSTR reactor was operated at pH 5.5, 80 rpm, 2 days HRT, 60 g COD L-1 d-1 organic loading rate (OLR) and 55 °C temperature with the given hydrogen yield of 205 ml H2 gCOD-1 along with acetic, butyric, propionic, and lactic acid as by-products. Continuous, single-chambered MECs fed with dark fermentation effluents were operated at an applied voltage of 0.5 V at 37 °C to obtain methane yield and production rate (MPR) of 290 ml CH4 gCOD-1 and 2700 ml CH4 L-1 at 8 days of hydraulic retention times (HRT). The overall process led to total energy recovery of 92.72% with 91% COD removal efficiency. Microbial community analysis reveals Thermoanerobacterium sp dominated in CSTR whereas exoelectrogens of Methanobacterium formicicum and Methanobacterium beijingense were found to be the chief dominant microbial species on anodic electrode of MECs.

Tanneries boost the local economic development, but lead to severe environmental pollution; hence, improving the environmental assessment of this sector is essential. In this paper, the Life Cycle Assessment method was applied to estimate impacts on the environment and human health of retanning, fatliquoring and dyeing. The analysis was performed from a “gate to gate” perspective. Moreover, sulpho chlorinated paraffin and epoxidized vegetable oil have been evaluated as alternative fatliquoring agents. The production of electricity required for the rotation of drums gives the main contribute to most of the impact categories, followed by the azo-dye production. Emissions of sulfur dioxide, nitrogen oxides, manganese, vanadium and nickel associated to power plants are the main sources of terrestrial acidification and particulate matter formation, as well as of human and marine toxicity (4.48·10−1 and 1.09·10−2 kg of 1,4-DBeq kg−1 crust leather, respectively). Nitrate loads from wastewater treatment and oxidative treatments affect heavily marine eutrophication (6.9·10−1 g N eq kg−1 crust leather). The use of epoxidized vegetable oil would affect human toxicity, ecosystem, metal and water resources depletion more than the use of sulpho chlorinated paraffin, mainly due to pesticides distribution and other cultivation practices. Phosphate and nitrate releases due to fertilization determine the high impact on the categories freshwater and marine eutrophication. Progress in increasing the conversion efficiency is demanded, but overall focus must be made on the substitution of fossil fuels with cleaner alternatives. The transition towards a circular economy is encouraged; increasing rates of reduction, reuse, recycle and recover of solid waste and tannery effluents are recommended. Agricultural practices with a reduced consumption of phytosanitary products and mineral fertilizers, alternative to conventional farming, would strongly contribute to increase the sustainability of epoxidized vegetable oil as alternative fatliquoring agent.

Organic micropollutants like pharmaceuticals, personal care products, pesticides and industrial chemicals have received an ever growing attention due to their adverse ecological effects in natural water bodies. A promising technology to remove the micropollutants from the wastewater is biocatalytic treatment using oxidoreductase enzymes. In order to improve removal efficiency and feasibility, the focus has been on developing enzyme-mediator systems and immobilisation techniques. Nonetheless, since oxidoreductase enzymes often promote coupling reactions, enzymatic reactions do not necessarily result in simpler compounds. Thus transformation products, which might be in equally or even more hazardous pollutants, can be still present in the wastewater after treatment. Therefore, the toxicity and ecological effects of the reaction products have to be investigated rigorously to ensure that the treatment mitigates the environmental and health related impacts.The objective of this paper is to give an overview of research carried out with oxidoreductase enzymes to treat different organic micropollutants and their mixtures along with real wastewater and to collect available information on different techniques, transformation products and toxicity. Though in most cases the reviewed enzymatic treatment methods resulted in less toxic effluent, the application of mediators, while facilitating higher transformation rates, increased the level of toxicity. Hence, it was concluded that the suitability of biocatalytic methods should be assessed from the perspective of toxicity beside the removal efficiency in order to allow the upscaling of the technology to a feasible and sustainable wastewater treatment solution.