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The use of microalgae and bacteria as a strategy for the startup of bioreactors for the treatment of industrial wastewater can be a sustainable and economically viable alternative. This technology model provides satisfactory results in the nitrification and denitrification process for nitrogen removal, organic matter removal, biomass growth, sedimentation, and byproducts recovery for added-value product production. The objective of this work was to evaluate the performance of microalgae and bacteria in their symbiotic process when used in the treatment of paper pulp industry wastewater. The experiment, lasting fourteen days, utilized four bioreactors with varying concentrations in mgVSS/L of microalgae to bacteria ratio (R1-100:100, R2-100:300, R3-100:500, R4-300:100) in the startup process. Regarding the sludge volumetric index (SVI), the results show that the R1 and R2 reactors developed SVI30/SVI10 biomass in the range of 85.57 ± 7.33% and 84.72 ± 8.19%, respectively. The lipid content in the biomass of reactors R1, R2, R3 e R4 was 13%, 7%, 19%, and 22%, respectively. This high oil content at the end of the batch, may be related to the nutritional stress that the species underwent during this feeding regime. In terms of chlorophyll, the bioreactor with an initial inoculation of 100:100 showed better symbiotic growth of microalgae and bacteria, allowing exponential growth of microalgae. The total chlorophyll value for this bioreactor was 801.46 ± 196.96 μg/L. Biological removal of nitrogen from wastewater from the paper pulp industry is a challenge due to the characteristics of the effluent, but the four reactors operated in a single batch obtained good nitrogen removal. Ammonia nitrogen removal performances were 91.55 ± 9.99%, 72.13 ± 19.18%, 64.04 ± 21.34%, and 86.15 ± 30.10% in R1, R2, R3, and R4, respectively. [Display omitted] • Microalgae and bacteria symbiotically initiated bioreactor start-up. • Initial inoculation concentrations were critical for photogranule development. • High total nitrogen removal efficiency in all bioreactor configurations. • Optimal setup boosts biomass and pigment. • Microalgae-bacteria consortium facilitated the production of valuable bioproducts. [ABSTRACT FROM AUTHOR]

Biomass can be used as an energy source to thermochemical conversion processes to biocrude production. However, the supply and dependence on only one biomass for biocrude production can be an obstacle due to its seasonality, availability, and logistics costs. In this way, biomass waste and agroindustrial residues can be mixture and used as feedstock to the hydrothermal co-liquefaction (co-HTL) process as an alternative to obtaining biocrude. In this sense, the present paper analyzed the biocrude yield influence of the co-HTL from a quaternary unprecedented blend of different biomasses, such as sugarcane bagasse, brewer's spent grain (BSG), sludge from a paper recycling mill (PRM), and microalgae (Chlorella vulgaris). In this way, a simplex lattice design was employed and co-HTL experiments were carried out in a 2000 mL high-pressure stirred autoclave reactor under 275 °C for 60 min, considering 15% of feedstock/water ratio. Significant effects in each feedstock and their blends were analyzed aiming to increase biocrude and biochar yield. It was found that the addition of microalgae is only significant when considered more than 50% into the blend with BSG and PRM sludge to increase biocrude yield. • Unprecedented blend (microalgae, sugarcane bagasse, BSG, and PRM sludge) in co-HTL. • Highest biocrude yield of 51.7% using microalgae as the only feedstock. • Second-highest biocrude yield (29%) for BSG and PRM sludge (synergetic interaction). • BSG and PRM sludge can complement co-HTL feedstock in low microalgae availability. • E RoI higher than one for 50% of microalgae, 25.8% of BSG, and 24.2% of PRM sludge. [ABSTRACT FROM AUTHOR]

Waste paper disposed in landfills notably contributes to greenhouse gas (GHG) emissions and impedes more sustainable, circular alternatives, such as recycling. In Hong Kong, this unsustainable approach is currently dominant as 68% of waste paper products are treated in landfills in 2020. To contextualize the impact of local waste paper management and explore mitigation potentials of circular alternatives, this paper develops a quantitative assessment framework around GHG emissions development trajectories. Combining guidelines of the Intergovernmental Panel on Climate Change (IPCC), national GHG inventories, and local parameters from life cycle analysis, five GHG emissions projections were simulated along the Shared Socioeconomic Pathways (SSPs) until 2060. Most recent baselines indicate that Hong Kong's current waste paper treatment generated 638,360 tons CO 2 -eq in 2020, comprising 1,821,040 tons CO 2 -eq from landfill and 671,320 tons CO 2 -eq from recycling, and −1,854,000 tons CO 2 -eq from primary material replacement. Proceeding along a Business-as-Usual scenario under SSP5, GHG emissions will dramatically increase to a net 1,072,270 tons CO 2 -eq by 2060, whereas a recycling-intensive scenario will lead to a net saving of −4,323,190 tons CO 2 -eq. To complement the quantitative evidence on the benefits of waste paper recycling, field research was conducted to explore the feasibility of circular policy innovation from the perspective of recycling stakeholders. These empirical qualitative and quantitative findings from stakeholders' business routines and material transactions provide crucial indications for policy and institutional innovation: Essentially, for Hong Kong to improve waste paper recycling capacities and facilitate a circular economy (CE), local stakeholders require support via fiscal policy measures (financial subsidies or tax reductions) and infrastructure improvements (delivery access and material storage). In sum, this study employs a novel analytical framework combining original qualitative and quantitative evidence to provide policy innovation towards circular, GHG emission-saving waste paper management. [Display omitted] • A new framework assessing greenhouse gas emissions from waste paper treatment. • Exploring long-term carbon neutrality pathways for managing waste paper. • Using empirical evidence from recycling stakeholders for circular policy innovation. [ABSTRACT FROM AUTHOR]

Abstract Many paper products are coated with plastic to improve their quality and stability. However, this limits recycling and recovery options and the plastic-coated waste paper is mostly disposed in landfills. Such practices are uneconomical and contrary to sustainable waste management. In this work enzymes of the white rot fungus Dichomitus squalens were investigated for possible delamination of plastic-coated waste paper. Enzymes were found capable to release the polyethylene foil from plastic-coated paper which resulted in 88.6–91.5% mass loss. The delamination rate, however, was depended on the ratio between plastic-coated paper and volume of enzyme filtrate. Results of a consequent experiment showed that enzymes are also efficient when plastic-coated paper is treated in a sequencing batch reactor resulting in 88.2–90.6% mass loss. The system was fully functional up to the 5th cycle; afterwards, the delamination rate reduced due to high thickness of the waste paper sludge. The enzyme activity, however, was still very high; with the laccase activity at the end of the experiment above 900 U/L and manganese peroxidase above 250 U/L. Our results demonstrated, that plastic-coated waste paper has the potential to be efficiently recovered instead of being disposed in landfills. Graphical abstract Image 1 Highlights • Enzymatic delamination of waste paper was investigated. • Enzymes were capable to release the polyethylene foil from the plastic-coated paper. • Treatment in a sequencing batch reactor is also possible. [ABSTRACT FROM AUTHOR]

At present, there is no reliable method in use that unequivocally describes paper industry material flows and makes it possible to compare geographical regions with each other. A functioning paper industry Material Flow Account (MFA) that uses uniform terminology and standard definitions for terms and structures is necessary. Many of the presently used general level MFAs, which are called frameworks in this article, stress the importance of input and output flows but do not provide a uniform picture of material recycling. Paper industry is an example of a field in which recycling plays a key role. Additionally, terms related to paper industry recycling, such as collection rate, recycling rate, and utilization rate, are not defined uniformly across regions and time. Thus, reliably comparing material recycling activity between geographical regions or calculating any regional summaries is difficult or even impossible. The objective of this study is to give a partial solution to the problem of not having a reliable method in use that unequivocally describes paper industry material flows. This is done by introducing a new material flow framework for paper industry in which the flow and stage structure supports the use of uniform definitions for terms related to paper recycling. This new framework is termed the Detailed Wheel of Fiber. [ABSTRACT FROM AUTHOR]

It is estimated that >400 Mt of board and paper are produced globally per year, and that 4.3–40 kg (dw) of sludge like material, pulp and paper mill sludge (PPMS), is generated for every tonne of product. PPMS are now more widely reused in agriculture as a soil amendment due to their high organic content of 40–50% by weight, perceived low toxicity and possible liming capabilities. Within this review article historic and recent literature on PPMS land spreading are combined with knowledge of European and UK regulation to explore the benefits, potential impacts and viability of land spreading PPMS. The review reveals that risks relating to potential N immobilisation in soils post-application can be readily mitigated, if desired, by coapplication of an N source, or even pre-treatment of sludge via composting. The benefits to crops have been demonstrated emphatically, while negative ecological impacts under typical field application rates have not been observed to date. The case is therefore strong for continued land application of the material as an environmentally responsible and sustainable use option. However, there are currently gaps in the literature regarding longer-term implications of PPMS applications in agriculture and in regards to the possible presence of emerging contaminants in some PPMS materials, both of which have been identified as areas that merit further research. • Land spreading paper pulp mill sludge (PPMS) offers economic and environmental benefit. • Characteristics and utility of PPMS vary with treatment level (primary vs secondary). • Co-application of N sources can prove beneficial in some cases. • Routine analysis and robust regulation prevent adverse outcomes from PPMS use. • Longer term studies on soil chemistry and ecology effects are warranted. [ABSTRACT FROM AUTHOR]

The total emission control target of water pollutants (e.g., COD and NH 4 –N) for a certain industrial sector can be predicted and analysed using the popular technology-based bottom-up modelling. However, this methodology has obvious uncertainty regarding the attainment of mitigation targets. The primary uncertainty comes from macro-production, pollutant reduction roadmap, and technical parameters. This research takes the paper and pulp industry in China as an example, and builds 5 mitigation scenarios via different combinations of raw material structure, scale structure, procedure mitigation technology, and end-of-pipe treatment technology. Using the methodology of uncertainty analysis via Monte Carlo, random sampling was conducted over a hundred thousand times. According to key parameters, sensitive parameters that impact total emission control targets such as industrial output, technique structure, cleaner production technology, and end-of-pipe treatment technology are discussed in this article. It appears that scenario uncertainty has a larger influence on COD emission than NH 4 –N, hence it is recommended that a looser total emission control target for COD is necessary to increase its feasibility and availability while maintaining the status quo of NH 4 –N. Consequently, from uncertainty analysis, this research recognizes the sensitive products, techniques, and technologies affecting industrial water pollution. [ABSTRACT FROM AUTHOR]

Pulp and paper industry produces massive amounts of sludge from wastewater treatment, which constitute an enormous environmental challenge. A possible management option is the conversion of sludge into carbon-based adsorbents to be applied in water remediation. For such utilization it is important to investigate if sludge is a consistent raw material originating reproducible final materials (either over time or from different manufacturing processes), which is the main goal of this work. For that purpose, different primary (PS) and biological sludge (BS) batches from two factories with different operation modes were sampled and subjected to pyrolysis (P materials) and to pyrolysis followed by acid washing (PW materials). All the materials were characterized by proximate analysis, total organic carbon (TOC) and inorganic carbon (IC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and N 2 adsorption isotherms (specific surface area ( S BET )and porosity determination). Sludge from the two factories proved to have distinct physicochemical properties, mainly in what concerns IC. After pyrolysis, the washing step was essential to reduce IC and to considerably increase S BET , yet with high impact in the final production yield. Among the materials here produced, PW materials from PS were those having the highest S BET values (387–488 m 2 g −1 ). Overall, it was found that precursors from different factories might originate final materials with distinct characteristics, being essential to take into account this source of variability when considering paper mill sludge as a raw material. Nevertheless, for PS, low variability was found between batches, which points out to the reliability of such residues to be used as precursors of carbon adsorbents. [ABSTRACT FROM AUTHOR]

In this study, hydrogen harvesting from fermentation of sugarcane bagasse (SCB) was promoted by maintaining synergism between sulfonated graphene (SGR) catalyst and paper mill sludge (PMS). The sulfonic acid (–SO 3 H) groups in the catalyst played a major role in destructing the β-1,4 glycosidic bonds of sugarcane bagasse, releasing readily biodegradable sugars into the fermentation medium. The cellulose, hemicellulose, and lignin conversion efficiency were improved by 127.5%, 495.0%, and 109.2%, respectively with 20 mgSGR/gVS catalyst addition, compared with the control samples. These values were also higher than those obtained by non-sulfonated graphene catalyst. The hydrogenation of sugarcane bagasse was maximized at a sulfonated graphene catalyst dosage of 60 mgSGR/gVS, providing the highest hydrogen harvesting of 4104 ± 321 mL. This was associated with an increase of the Proteobacteria phyla up to 52.0%, Firmicutes phyla to 13.9%, and Acinetobacter sp. to 39.8% compared with only 37.0%, 11.3% and 11.1% in the control assay respectively. Moreover, sulfonated graphene catalyst supplementation promoted the acetate fermentation reaction pathway by increasing the acetate/butyrate ratio up to 4.1. Nevertheless, elevating the catalyst dosage up to 120 mgSGR/gVS reduced the hydrogen harvesting (1190 ± 92 mL) due to the release of furfural (1.76 ± 0.02 g/L) in the fermentation cultures, deteriorating the microbes' internal composition and metabolism bioactivities. Finally maximizing the hydrogen productivity from sugarcane bagasse is feasible by incorporation of paper mill sludge and sulfonated graphene catalyst at dosage not exceeding 60 mgSGR/gVS. However, investigating the recyclability and disposal of digestate containing sulfonated graphene catalyst and the associated economic feasibility needs more attention in the future. [Display omitted] • Sugarcane bagasse was fermented by paper mill sludge supported on sulfonated graphene. • Synergism between paper mill sludge/sulfonated graphene improved bio-H 2 by 4.8 times. • Sulfonated graphene promoted acetate fermentation (HAc/HBu of 4.1) and inhibited HPr. • Acinetobacter degrading phenol increased by 3.6 folds with sulfonated graphene catalyst. • MolDock visualized H-bonding in hydrogenase protein/sulfonated graphene interaction. [ABSTRACT FROM AUTHOR]

Pulp-and-paper mills produce various types of contaminants and a significant amount of wastewater depending on the type of processes used in the plant. Since the generated wastewaters can be potentially polluting and very dangerous, they should be treated in wastewater treatment plants before being released to the environment. This paper reviews different wastewater treatment processes used in the pulp-and-paper industry and compares them with respect to their contaminant removal efficiencies and the extent of greenhouse gas (GHG) emission. It also evaluates the impact of operating parameters on the performance of different treatment processes. Two mathematical models were used to estimate GHG emission in common biological treatment processes used in the pulp-and-paper industry. Nutrient removal processes and sludge treatment are discussed and their associated GHG emissions are calculated. Although both aerobic and anaerobic biological processes are appropriate for wastewater treatment, their combination known as hybrid processes showed a better contaminant removal capacity at higher efficiencies under optimized operating conditions with reduced GHG emission and energy costs. [ABSTRACT FROM AUTHOR]

Pulp and paper mill biomass boilers generate large quantities of ash in Canada with British Columbia (BC) being the highest ash generating province followed closely by Quebec. Generally, the generated ash is landfilled, particularly in BC, with only a small amount being used beneficially. It is anticipated that the difficulty associated with the management of ash will worsen over time as the industry increases its reliance on green fuel. Thus, there is a strong need to identify beneficial uses of pulp and paper boiler ash for the sake of environmental and economic sustainability. The purpose of this report is to provide the first step in this direction, a review of proposed or implemented uses for coal and hog (or wood) ash around the world. Considering both the properties of the ash and local opportunities, this could be the first step toward screening the applications that may apply to individual mills. Several large-scale practices use ash, such as land application (as a nutrient source or as a liming agent), use in the construction industry (as a replacement for cement or as a fill material), and reclamation of mine sites and stabilization of unpaved forest roads. In some cases, relatively small-scale applications have been used which included uses such as a compost component, agent for pH adjustment of liquid streams and slurries, blasting abrasive, and source of quartz for glass manufacturing to name a few. It is important to note that the chemical nature of both fly and bottom ashes can be quite variable due to the type of wood residues combusted as well as combustion equipment used and must be considered in identifying beneficial applications. • General ash characterization is not enough to find useful applications of ash. • Ash use in the liming agent requires different properties than ash use in concrete. • Ash must be characterized according to its application requirements. • PPM ash can mainly be used for concrete, ag lands, liming agent, and forest roads. [ABSTRACT FROM AUTHOR]

In this work, heterogeneous photocatalysis was used to treat pulp and paper mill effluent (PPME). Magnetically retrievable Fe 2 O 3 -TiO 2 was fabricated by employing a solvent-free mechanochemical process under ambient conditions. Findings elucidated the successful incorporation of Fe 2 O 3 into the TiO 2 lattice. Fe 2 O 3 -TiO 2 was found to be an irregular and slightly agglomerated surface morphology. In comparison to commercial P25, Fe 2 O 3 -TiO 2 exhibited higher ferromagnetism and better catalyst properties with improvements in surface area (58.40 m 2 /g), pore volume (0.29 cm 3 /g), pore size (18.52 nm), and band gap (2.95 eV). Besides, reusability study revealed that Fe 2 O 3 -TiO 2 was chemically stable and could be reused successively (five cycles) without significant changes in its photoactivity and intrinsic properties. Additionally, this study demonstrated the potential recovery of Fe 2 O 3 -TiO 2 from an aqueous suspension by using an applied magnetic field or sedimentation. Interactive effects of photocatalytic conditions (initial effluent pH, Fe 2 O 3 -TiO 2 dosage, and air flow-rate), reaction mechanism, and the presence of chemical oxidants (H 2 O 2 , BrO 3 − , and HOCl) during the treatment process of PPME were also investigated. Under optimal conditions (initial effluent pH = 3.88, [Fe 2 O 3 -TiO 2 ] = 1.3 g/L, and air flow-rate = 2.28 L/min), the treatment efficiency of Fe 2 O 3 -TiO 2 was 98.5% higher than the P25. Based on Langmuir-Hinshelwood kinetic model, apparent rate constants of Fe 2 O 3 -TiO 2 and P25 were 9.2 × 10 −3 and 2.7 × 10 −3 min −1 , respectively. The present study revealed not only the potential of using magnetic Fe 2 O 3 -TiO 2 in PPME treatment but also demonstrated high reusability and easy separation of Fe 2 O 3 -TiO 2 from the wastewater. [ABSTRACT FROM AUTHOR]

The pulp-paper industry is one of the main industrial sectors that produce massive amounts of residual sludge, constituting an enormous environmental burden for the industries. Traditional sludge management practices, such as landfilling and incineration, are restricted due to mounting environmental pressures, complex regulatory frameworks, land availability, high costs, and public opinion. Valorization of pulp-paper industry sludge (PPS) to produce high-value products is a promising substitute for traditional sludge management practices, promoting their reuse and recycling. Valorization of PPIS for biorefinery beneficiation includes biomethane, biohydrogen, bioethanol, biobutanol, and biodiesel production for renewable energy generation. Additionally, the various thermo-chemical technologies can be utilized to synthesize bio-oil, hydrochar, biochar, adsorbent, and activated carbon, signifying potential for value-added generation. Moreover, PPIS can be recycled as a byproduct by incorporating it into nanocomposites, cardboard, and construction materials development. This paper aims to deliver a comprehensive overview of PPIS management approaches and thermo-chemical technologies utilized for the development of platform chemicals in industry. Substitute uses of PPIS, such as making building materials, developing supercapacitors, and making cardboard, are also discussed. In addition, this article deeply discusses recent developments in biotechnologies for valorizing PPIS to yield an array of valuable products, such as biofuels, lactic acids, cellulose, nanocellulose, and so on. This review serves as a roadmap for future research endeavors in the effective handling of PPIS. [Display omitted] • Valorization of pulp-paper industry sludge is a sustainable option for getting waste to wealth. • Pre-treatment of pulp-paper industry sludge helps in yielding platform chemicals in the biorefinery scenario. • Pulp-paper industry sludge is a sustainable feedstock for renewable energy production. • Biochars derived from pulp-paper industry sludge exhibited excellent adsorption performance for metals removal. [ABSTRACT FROM AUTHOR]

The complexity of residual toxic organics from biologically treated effluents of pulp and paper mills is a serious concern. To date, it has been difficult to choose the best treatment technique because each of the available options has advantages and drawbacks. In this study, two different treatment techniques using laboratory-scale aerobic sequencing batch reactors (SBRs) were tested with the same real recycled paper mill effluent to evaluate their treatment efficiencies. Two attached-growth SBRs using granular activated carbon (GAC) with and without additional biomass and a suspended-growth SBR were used in the treatment of real recycled paper mill effluent at a chemical oxygen demand (COD) level in the range of 800–1300 mg/L, a fixed hydraulic retention time of 24 h and a COD:N:P ratio of approximately 100:5:1. The efficiency of this biological treatment process was studied over a 300-day period. The six most important wastewater quality parameters, namely, chemical oxygen demand (COD), turbidity, ammonia (expressed as NH 3 –N), phosphorus (expressed as PO 4 3 –P), colour, and suspended solids (SS), were measured to compare the different treatment techniques. It was determined that these processes were able to almost completely and simultaneously eliminate COD (99%) and turbidity (99%); the removals of NH 3 –N (90–100%), PO 4 3 –P (66–78%), colour (63–91%), and SS (97–99%) were also sufficient. The overall performance results confirmed that an attached-growth SBR system using additional biomass on GAC is a promising configuration for wastewater treatment in terms of performance efficiency and process stability under fluctuations of organic load. Hence, this hybrid system is recommended for the treatment of pulp and paper mill effluents. [ABSTRACT FROM AUTHOR]

Waste paper fly ash (WPFA) and bottom ash (WPBA), derived from fluidised bed combustion of a paper recycling plant, exhibit cementitious properties owing to its mineralogical composition, and hence, could be proposed as a hydraulic binder. However, it may also contain some traces of heavy metals. Considering it is necessary to understand the effect of reusing any kind of waste on the environment, this study proposes of reusing WPFA/WPBA as a hydraulic road binder by evaluating its mineralogical composition and leaching activity. Chemical, physical, and mineralogical properties of raw WPFA/WPBA and the microstructural evolution of binders were carried out. Results showed that both ashes undergo hydration reactions while showing some cementitious properties by forming C–S–H gel, Friedel's salt, and calcite. According to the European standard EN 13282–1, both WPFA and WPBA can be categorised as N1 considering they reach 5.3 and 3.6 MPa, respectively, at 56 days. Furthermore, the mechanical performance of various soils was improved by using WPFA and WPBA as a binder. From the environmental point of view, the amount of barium in WPFA and WPBA, which is the main problem, was significantly decreased by using these ashes as a binder. • Ashes from a plant using 100% recycled paper to produce paper are studied. • WPFA and WPBA have cementitious properties. • The hydrated products are calcite, C–S–H gel, and Friedel's salt. • Implementation of WPFA on six different soils was successful. • A stabilised soil with WPFA can be categorised as an inert material. [ABSTRACT FROM AUTHOR]

Paper mill Electrostatic Precipitator (ESP) ash contains a mixture of alkali metal chloride (34.2 %) and sulfate (84.2 %) which has serious negative effects on the environment and makes it more expensive and constrained to dispose ESP ash. Therefore, handling and recycling ESP ash demands extra thought when disposing of it. Present study, aimed to separate chloride and sulfate from ESP ash using electrochemical membrane technology. Three different concentrations of ESP ash solution such as 200 g L-1, 320 g L-1 and 450 g L-1 were used as the electrolyte. Ti/TiO 2 –IrO 2 –RuO 2 and titanium (Ti) are used as anode and cathode respectively. Caustic and sulfate solutions were recovered at the respective compartments. The collected sulfate solution was dried by solar light to convert 99 % sulfate salts as confirmed by Energy-dispersive X-ray analysis (EDAX) analysis. Recovered sulfate salt was used for the dye fixing process, in which the colour fixing difference of ΔE value was about 2.10 and the strength of the dye was about 86.72 %. Therefore, the textile industry can repurpose the recovered sulfate salt for the dye fixing process. [Display omitted] • An electrochemical membrane process was adopted to treat the ESP ash slat. • Na2SO4, Cl2 and alkali were recovered in a single electrochemical process. • Double layer cation exchange membrane provided good current efficiency. • Recovered Na2SO4 was used in the dyeing process and ΔE is 2.10 and dye strength is 86.72 %. • Sulfate concentration does not affect the CEM in the electrochemical process. [ABSTRACT FROM AUTHOR]

The amount of compostable bioplastics collected with the food waste is constantly growing, particularly due to the bags used for collection. According to the Italian legislation, compostable bioplastics must be accepted by all biological treatment plants, including aerobic and anaerobic facilities. Anyway, the compostability standard requires only the assessment of the aerobic degradability, while it is generally not required to test the behaviour under anaerobic conditions. This aspect is evaluated in the paper, where the anaerobic degradability of bioplastic bags used for the food waste collection is assessed. First, Biochemical Methane Potential (BMP) tests were performed on four commercial types of bioplastic bags, including those designed only for the collection of food waste and the shoppers, that can be reused for the same purpose. Subsequently, an innovative approach for this kind of substrate was applied, subjecting two bags to semi-continuous co-digestion tests together with the food waste. Both tests were performed by comparing the behaviour of bioplastic bags with that of an alternative collection paper bag. Finally, tests to evaluate the influence of physical phenomena on the degradation of bioplastics were performed to better understand the results of biological tests. BMP tests indicated a good degradability (>71%) of bioplastic bags, while semi-continuous tests showed a much lower degradability (<27%), confirmed by the observation of the undigested bag pieces. On the contrary, the paper bag presents interesting characteristics, because its degradability in the semi-continuous tests (82%) resulted even higher than that observed in the BMP tests (74%). These results highlight an important difference between the bags mono-digestion by means of BMP tests and the semi-continuous co-digestion tests with food waste, which better simulate the full-scale operational conditions. [Display omitted] • Bioplastic and paper bags were tested with BMP and semi-continuous digestion tests. • Paper bags show a good degradability in both the tests (>74%). • The BMP tests on bioplastic bags indicate a good degradability (>71%). • Semi-continuous digestion of bioplastics with food waste shows a low degradability. • The degradability of bioplastics is influenced by physical factors. [ABSTRACT FROM AUTHOR]

The carbonization of lignocellulosic biomass with ionic liquids (ILs) are considered as an advantageous approach for the preparation of carbonaceous materials. The commonly used imidazolium and pyridinium based ILs have drawbacks such as toxicity, resistance to biodegradation, high cost and viscosity. These issues can be mitigated by diluting ILs with water, although excessive water content above 1 wt% can reduce the solubility of biomass. This research aims to investigate the potential of pretreating wastepaper with a "fully green" ILs, amino acid-based IL with high water content, followed by pyrolysis without IL, in enhancing the properties of biochar. For this purpose, the paper was treated with an aqueous solution of IL cysteine nitrate ([Cys][NO 3 ]), and the IL was not involved in the pyrolysis process to prevent the formation of secondary gaseous pollutants. The findings revealed that the hemicellulose and mineral filler in the paper were eliminated during pretreatment, leading to higher carbon content but lower oxygen content. As a result, the biochar exhibited micropores of 0.42 cm3g-1 and a specific surface area of 1011.21 m2 g−1. The biochar demonstrated high adsorption capacities for Cd2+, enrofloxacin, bisphenol A, ciprofloxacin, and tetracycline, with values of 45.20 mg g−1, 49.82 mg g−1, 49.90 mg g−1, 49.88 mg g−1, and 49.65 mg g−1, respectively. The proposed mechanism for the adsorption of enrofloxacin by the biochar primarily involves physical adsorption such as pore filling and electrostatic interactions, along with chemical adsorption facilitated by graphitic nitrogen. [Display omitted] • Amino acid-based IL with high water content removed the hemicellulose and minerals. • The specific surface area was four times of that of biochar without pretreatment. • More nitrogen was retained in the biochar and provided adsorption sites. [ABSTRACT FROM AUTHOR]

The pulp and paper industry consumes a huge amount of water and releases more polluted and colored wastewater every year. Many conventional techniques are used in the treatment of paper industry wastewater. However, for color removal from paper mill effluent, there is no proven method so far, on an industrial scale. Due to high energy input and high cost, there is an urgent need to find out a new technique that must be sustainable, economical, and environment friendly. Various methods have been investigated on bench scale and pilot scale also but no proven method for color removal on an industrial scale. The paper provides an overview of the color removal techniques from different sources of pulp and paper mill wastewater discharged by various industries. The review described various components involved in various processes for color removal from paper mill waste water. The present works focus on processes like chemical, chemical/physical, biological, physicochemical, and electrochemical applied in color removal from paper mill wastewater. The present review gives key information on the effectiveness, use, betterment, and limitations of numerous methods of treatment targeted at color removal from paper mill wastewater using various techniques still under evolution. • A critical study made on color removal from paper mill effluent using various methods. • Examined color removal efficiencies using conventional and advanced techniques. • Study on Cost analysis in color removal from paper mill effluent. • Future research suggestions described for better implementation of the processes. [ABSTRACT FROM AUTHOR]

This article describes a study on the viability of using waste from the paper industry: biomass boiler ash and green liquor dregs to fabricate mortars and concretes. Both types of ash were characterized by obtaining their chemical and mineralogical composition, their organic matter content, granulometry, adsorption and other common tests for construction materials. Seven different mortars were fabricated, one for reference made up of cement, sand, and water, three in which 10, 20, or 30% of the cement was replaced by biomass ash, and three others in which 10, 20, or 30% of the cement was replaced with dregs. Test specimens were fabricated with these mortars to conduct flexural and compression tests. Flexural strength is reduced for all the mortars studied. Compressive strength increases for the mortars fabricated with biomass ash and decreases for the mortar with dregs. Finally, 5 concretes were made, one of them as a reference (neither biomass ash nor dregs added), two of them with replacements of 10 and 20% of biomass ash instead of cement and another two with replacements of 10 and 20% of dregs instead of cement. The compressive and tensile splitting strength increase when a 10% of ash is replaced and decrease in all the other cases. The modulus of elasticity always decreases. [ABSTRACT FROM AUTHOR]

Pseudoestrogene bisphenol A (BPA) can be important ingredient of thermochromic inks, increasingly used materials in thermal printing paper, security printing, advertising, design and as temperature indicators in medicine and food industry. BPA mass fraction in thermochromic inks can be up to several percent. Hence, disposal of items with thermochromic prints pose a risk of environmental pollution. In this work BPA mass fraction was monitored during anaerobic degradation of papers with thermochromic prints in soil in both matrices: papers and soil. The degradation conditions simulated deeper layers of waste at a landfill site. Six types of papers with prints of thermochromic ink containing 2% of BPA were subjected to anaerobic degradation over up to 150 days. Initial mass fractions of BPA in papers decreased form (126–460) μg/g to (

Generally, the mechanical strength and stiffness of old corrugated cardboard (OCC) waste paper are decreased after multiple recycling procedures. Surface sizing starch, which is extensively used in the surface sizing of paper making, accumulates after dissolving from the fibers and is transformed into pollutant during the OCC re-pulping process. To overcome the pollution and reutilization problem of the waste starch during the recycling process of OCC paper, waste starch was ionized using hydrogen peroxide (H 2 O 2) to improve the mechanical properties of OCC paper during the reutilization. The results showed that the carboxyl group of waste starch increased with an increasing degree of ionization, resulting in enhanced copper ion adsorption capacity. Furthermore, the retention rate of the modified starch in the wet-end increased from 18.0% to 48.2%. The OCC paper presented the highest burst index and tensile strength of 8.94 kPa m2/g and 112.5 N m/g, respectively, when MS-2 was added. This work has great significance for implementation of the cleaning production of OCC waste papers and the reutilization of the waste starch. Image 1 • Waste starch was ionized to improve the mechanical properties of OCC paper. • The starch content in OCC pulp wastewater reached 4.5–4.8 g/L. • The waste starch was oxidized by H 2 O 2 to give anion carboxylic groups. • The retention rate of the modified starch was 30.2% higher than waste starch. [ABSTRACT FROM AUTHOR]

Pulp and paper mill sludge is a waste stream derived from the pulp and paper making industry, comprised of organic and inorganic material in the form of cellulose, hemicellulose, lignin and ash. In South Africa, approximately fivefour hundred thousand wet tonnes are produced per annum and is currently disposed via landfilling or incineration. However, these disposal methods raise environmental and financial concerns. This waste stream is an attractive feedstock for fermentable sugars, mainly glucose, recovery and can be redirected for valorisation as a feedstock for microbial fermentation to produce value-added products. Sugar recovery by enzymatic hydrolysis, as opposed to acidic hydrolysis, is a promising approach but is hampered by the lignin and inorganic material found in pulp and paper mill sludge. Several treatment steps to reduce or remove these components prior to enzymatic hydrolysis are assessed in this review. Pretreatment improves hydrolysis of cellulosic fibres and ensures a substantial yield of sugars. • Pulp and paper mill sludge is a suitable source of fermentable sugar. • Pulping and paper making processes can influence pulp and paper mill sludge properties. • Cost efficient strategies are suggested to promote enzymatic hydrolysis. • Pretreatment can help overcome challenges encountered with enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

The effects of doping of ZnO and Nb 2 O 5 solids with Fe 2 O 3 (1.4 wt%) and Ag 2 O (1.4 wt%) on its surface and catalytic properties were investigated, as well as its photocatalytic performance on the degradation of a pulp and paper wastewater (PPW). The catalysts were characterized by XRD, SEM, photoacoustic spectroscopy (PAS), NH 3 -TPD and textural analysis. The results obtained revealed that Fe 2 O 3 doping of Nb 2 O 5 conducted at 500 °C resulted in an increase of about 116% for S BET while Ag 2 O treatment exerted a decrease of 33% for S BET of the doped adsorbents. Doping ZnO with Fe 2 O 3 or Ag 2 O led to an increase of 80% for S BET . Iron and silver doping also led to a decrease in band gap energy of at least 6%. The addition of 1.4 wt% Ag 2 O on ZnO followed by calcination at 500 °C resulted in an increase of 11% in the value of the reaction rate constant ( k ap ) for COD reduction under UV radiation. The treatment of Nb 2 O 5 with 1.4 wt% Ag 2 O increased by a factor of 2.04 the value of k ap for the reaction taking place under VIS radiation. The catalysts partially reduced the organic load and the real colour of the wastewater, allowing the achievement of the specifications for release into rivers, so photocatalysis could be an alternative for pulp and paper wastewater final polishing. [ABSTRACT FROM AUTHOR]

China's paper industry development is rapid, but the recycling rate of China's waste paper has been low all the time. Meanwhile, material flow analysis can help determine the flow of waste paper, and life cycle assessment (LCA) is the methodological framework for quantifying greenhouse gas emissions. Therefore, present study integrates these two methods into the model construction of China's waste paper recycling decision system. Present study constructs a benchmark model of China's waste paper recycling decision system in 2017, focusing on the impact of nonstandard waste paper recycling on the economic and environmental benefits of China's domestic waste paper recycling system. This model construction is followed by sensitivity analysis of the relevant parameters affecting the efficiency of the waste paper recycling system. Finally, present study forecasts the system's economic benefits and greenhouse gas (GHG) emissions in the context of integrating and regulating nonstandard recycling vendors. The results show that the economic benefit of China's waste paper recycling in 2017 is approximately 458.3 yuan/t and that the GHG emissions are 901.1 kgCO 2 eq. The standard recovery rate and nonstandard recovery acceptance rate will both have a significant impact on the system's economic benefits and improve the GHG emissions structure. In the context of integrating nonstandard recycling enterprises and individual recycling vendors, the economic benefits will rise to 3312.5 yuan/t in 2030, while GHG emissions will rise to 942.9 kgCO 2 eq. Present study can play a certain guiding role for policy makers in formulating waste paper recycling industry specifications and formulating relevant policies. • Present study constructs the life cycle framework of Chinese paper and paperboard by the combination of MFA and LCA. • Quantitative analysis of the economic benefits and GHG emissions generated by China's waste paper recycling system. • Sensitivity analysis on the main parameters of the economic and environmental benefits of the waste paper recycling system. • Benefits of China's waste paper recycling from 2018 to 2030 are evaluated by integrating nostandard and standard recycling. [ABSTRACT FROM AUTHOR]

Abstract The pulp and paper industry is highly dependent on forest and water resources. It has more concerns on fair utilization of these resources and their conservation for its further expansion. Present study emphasizes on the use of rice straw (agro waste) in papermaking to protect wood based resources. It further deals with ozone bleaching (Z) prior to elemental chlorine free bleaching that proved to be significant in terms of reducing the effluent load specially the reduction in toxic, recalcitrant and carcinogenic compounds. Z based sequences resulted in pulp brightness of ∼85% that was 3.6% higher than the elemental chlorine free bleaching. Bleached pulps of Z based sequences were found to be having better strength properties than elemental chlorine based sequence and thus may be adopted as improved bleaching technology. The analysis of handsheets prepared after pulp bleaching was performed using X-Ray diffraction, ATR-FTIR and SEM. Incorporating ozone stage resulted in marked reduction of 58% and 63% in total solids in bleaching wastewater. Reduction of more than 80% in BOD, COD and adsorbable organic halides was achieved in Z based bleaching in comparison to chlorine bleaching. The amount of chlorophenols, guaiacols, catechols, vanillins and syringols became negligible (approx. 90% reduction) in effluents of Z based bleaching sequences. The chlorine dioxide followed by peroxide bleaching after Z stage was found to be the most promising to reduce the effluent load. Graphical abstract Image 1 Highlights • Ozone stage was incorporated prior to bleaching to reduce wastewater pollution. • Ozone based sequences showed higher brightness than conventional bleaching process. • Ozone bleaching showed better tensile and burst indices than elemental chlorine. • COD and BOD of bleaching effluent was reduced by 80% in ozone based sequences. • Chlorolignin compounds were reduced by 90% in effluent of ozone based sequences. [ABSTRACT FROM AUTHOR]

Paper industries are water-intensive industries that produce large amount of wastewater containing dyes, toxicity and high nutrient content. These industries require sustainable technology for their waste disposal and MEC could be one of them. However, effective MEC operation at neutral pH and ambient temperature requires economical and efficient cathodes that are capable to treat indusial wastewater along with recovery of energy/biohydrogen. Co-deposits of Nickel, Nickel–Cobalt and Nickel–Cobalt–Phosphorous on the surface of SS and Cu base metals distinctly were used as cathodes in MEC for the concurrent treatment of real paper industry wastewater and biohydrogen production. MECs were utilized in batch mode at neutral pH, applied voltage of 0.6 V and 30 ± 2 °C temperature with paper industry wastewater and activated sludge as microbial sources. The fabricated Nickel–Cobalt–Phosphorous gives the higher hydrogen production rate of 0.16 ± 0.002 m3(H 2) m−3d−1 and 0.14 ± 0.002 m3(H 2) m −3d −1 respectively, with ~33–42 % treatment efficiency for a 500 ml wastewater in 7-day batch cycle in both the cases; while it is lowest in the case of the control cathodes (SS1 (0.07 ± 0.002 m3(H 2) m−3d−1) & Cu1 (0.06 ± 0.004 m3(H 2) m−3d−1)). It was also found that fabricated cathodes have the capability to treat industrial wastewater at ambient conditions efficiently with higher energy recovery. Prepared cathodes show enhanced hydrogen production and treatment efficiency as well as are competitive to some reported literature. [Display omitted] • The fabricated cathodes exhibited higher electrochemical catalytic activity in real paper industry wastewater. • MECs were used concurrently for energy recovery and treatment of real paper industry wastewater. • Reaction inside MECs can be enhanced by depositing Ni–Co–P based particle on electrode surface. • Ni-Co-P co-deposits attained the maximum H 2 production rate of 0.16-0.06 ±0.002 m3(H 2) m-3d-1 with ~42 % COD reduction. • Higher biohydrogen production, cathodic efficiency and energy recovery were obtained with co –deposited cathode materials. [ABSTRACT FROM AUTHOR]

In this study, a mixture of waste plastics and papers were pyrolyzed under mild conditions in batch and tubular reactors. The decomposition reactions were enhanced by the use of synthetic zeolite-based catalysts to obtain a higher yield of volatiles and modifying the product composition. Especially the decomposition reactions and the product properties obtained from the different reactors were compared. Gases were analysed by GC-FID and GC-TCD. This fraction contains hydrogen, carbon-monoxide, carbon-dioxide and hydrocarbons. The pyrolysis oils have oxygen-containing compounds, such as alcohols, aldehyde, ketones, carboxylic acids or phenol and its derivative. Not only the reactor configurations but also the catalysts had an effect to the product properties, because the catalysts with alkali characters showed advanced behaviour in the reduction of oxygenated hydrocarbons, while high synthetic zeolite catalysts can increase the saturation and isomerization reactions. The long-term behaviour of the pyrolysis oils was followed by an accelerated aging test at 80 °C till 7 days. The catalysts can effectively reduce the rate of density and viscosity increase during the aging and the alkali catalysts showed beneficial properties in reducing the acidic components. In general, the aging properties were more favorable for pyrolysis oils obtained from the tubular reactor compared with the results in batch reactor. • Co-pyrolysis of plastic and paper wastes were investigated. • Better product properties could be obtained from tubular reactor. • Batch process can supported the in-situ saturation of olefins. • High alkali content catalysts can improve the corrosion properties of light oils. • Light oils had high TAN and can occur very low weigh loss. [ABSTRACT FROM AUTHOR]

This study aims to investigate the sewage sludge (SS) drying process by incorporating a by-product formed in the pulp and paper industry (green liquor dregs - GLD) as drying adjuvant. Through an innovative approach, the drying kinetics was modelled, and the final dried product was tested for soil applications. After the characterization phase, small cylinders of SS without and with 0.15 g GLD g SS−1 wb (SS_GLD) were dried in isothermal conditions at 70, 100, and 130 °C. The experimental data were fitted by Fick's second law and thin-layer models, and good results were achieved in both cases (R2 > 0.98 and RMSE <0.05). Although only a slight improvement was observed, the best conditions for drying biosolids were found with the addition of GLD at 130 °C, where the drying rate was 30.88 gH 2 O kg−1 SS wb min−1. In this condition, a decrease of 8% in the energy required for moisture evaporation was observed. Regarding the phytotoxicity tests with Lepidium sativum L. (garden cress), 60% improvement in EC 50 was noticed for the sample with GLD when compared to the raw SS. The dried product SS_GLD complied with the regulations for soil applications regarding the potentially toxic metals (Cr, Ni, Cu, Pb, Zn, and Cd), and promoted an increase in soil organic matter and pH. However, further and in-depth studies should be conducted to assess the potential of SS_GLD application in agricultural soil. • Fick's second law and thin-layer models described adequately the experimental data. • The maximum drying rate was obtained for SS with GLD at 130 C. • GLD contain a low concentration of potentially toxic metals but high alkalinity. • SS with GLD mixture increased the biomass content and raise soil pH. [ABSTRACT FROM AUTHOR]

Land-use change in the boreal forest region leads to agriculture to be carried out on acid, shallow and low fertility soils. To correct soil fertility and promote crop productivity, manure and inorganic fertilizers are added, increasing the risk for greenhouse gas emissions (GHGE). To reduce the reliance on synthetic soil amendments while taking advantage of locally relevant industrial by-products, wood ash (WA) and paper sludge (SL) have been proposed as soil amendments for a range of soil types. We posited that amending soils with WA , SL and biochar will improve soil health parameters and fertility of boreal soils. Microbial activity resulting to nitrogen losses and availability were assessed. WA had a stronger ameliorative effect on acid boreal soils compared to SL. Both WA and SL increased soil microbial biomass and basal respiration resulting in higher net mineralization and thus significant increases in CO 2 emissions. Co-application of urea with WA or SL further increased net mineralization compared to when used independently. Conversely, the biochar's effect was short-lived and not significant. Nevertheless, addition of biochar was shown to reduce CO 2 emissions in all cases except in WA amended soils. No significant differences were observed in CH 4 emissions across all treatments. WA and SL may improve soil fertility and quality but could also contribute significantly to GHG emissions in acid boreal soils. Further research is recommended to assess the mitigating effect of various biochar feedstocks on GHG emissions when co-applied with WA and SL. • The effect of wood ash and paper sludge on acid soils was tested in incubation tests. • Both increased the soil microbial biomass, respiration, and net mineralization. • Greenhouse gas emissions were larger for paper sludge amended soils. • Supplementing biochar to wood ash increased soil CO 2 fluxes. • Supplementing biochar to paper sludge or limestone ash reduced soil CO 2 fluxes. [ABSTRACT FROM AUTHOR]

The present study investigated the use of algae biorefinery waste and wastepaper in the preparation of cost-effective and eco-friendly xerogels for the removal of congo red (CR) and Fe2+. The xerogel properties such as density, swelling degree and porosity were modified by incorporating alginate extracted from the brown seaweed Cystoseira trinodis. The developed biosorbents exhibited a light and porous network structure and were characterized by a fast uptake of CR and Fe2+ and adsorption efficiency was increased at pH 6–8. The equilibrium adsorption capacity was found to be 6.20–7.28 mg CR g−1 biosorbent and 8.08–8.39 mg Fe2+ g−1 biosorbent using different xerogels. The adsorption of CR obeyed first-order kinetics, while, Fe2+ followed second-order kinetics. Intraparticle diffusion model suggested a boundary layer effect. The adsorption capacity was maximally obtained as 41.15 mg g−1 and 169.49 mg g−1 for CR and Fe2+ using wastepaper/ Spirulina and wastepaper/alginate/ Spirulina xerogel, respectively. Temkin isotherm fitted better to the equilibrium data of CR adsorption than Langmuir and Freundlich models. While, equilibrium data of Fe2+ exhibited a best fit to both Langmuir and Freundlich models. Additionally, the Dubinin-Radushkevich isotherm suggested that adsorption mechanism of CR or Fe2+ is predominately physisorption. Investigation of thermodynamic parameters such as ΔH° and ΔS° and ΔG° confirmed the feasibility, spontaneity, randomness and endothermic nature of the adsorption process. Electrostatic attraction, H-bonding and n-π interactions were mainly involved in the biosorption process of CR. The results of this study showed that the developed xerogels could be effectively applied for dye and heavy metal removal at low concentrations. Image 1 • Algal biorefinery and paper wastes were utilized for the development of xerogels. • Xerogels effectively adsorbed congo red and Fe (II) from aqueous solution. • Incorporation of alginate into xerogels affected their physico-chemical properties. • The adsorption mechanism was predominately physisorption. • Temkin isotherm well suited CR adsorption, while Langmuir and Freundlich best fitted Fe adsorption. [ABSTRACT FROM AUTHOR]

Organic waste management in environmentally sustainable way is important not only to reduce the negative impacts on ecosystems but also valorizing the waste resources. Herein we evaluated the potential of wood ash (WA) and paper sludge (PS) wastes from a pulp and paper mill as potting media and their effects on the physicochemical properties of podzolic soil. WA, PS and biochar (BC) was mixed in different combinations with a sandy loam podzolic soil. Potting media treatments included: T1–soil (negative control); T2–PromixTM (positive control); T3–50%soil+50%WA; T4–75%soil+25%WA; T5–50%soil+50%PS; T6–75%soil+25%PS; T7–75%soil+25%BC; T8–25%soil+50%WA+25%BC; T9–50%soil+25%WA+25%BC; T10–25%soil+50%PS+25%BC; T11–50%soil+25%PS+25%BC, T12– 25%soil+25%WA+25%PS+25%BC and replicated three times. Potting media treatments expressed significant (p < 0.00) effects on pH, bulk density, total porosity, field capacity, plant available water (PAW) and water retention curves. Potting media amended with WA showed high pH range (8–12) while PS amendments exhibited pH in range where most plant nutrients are available (6.5–7.5). Results depicted significantly lower bulk density, and increased total porosity and water holding capacity of potting media amended with WA and PS. BC addition further enhanced the water retention properties compared to combinations without BC. T6, T10 and T11 produced higher amounts of PAW with desired pH compared to T1 and T2. WA, PS and BC showed high potential for developing podzolic soil-based potting media, but their effects on plant growth and elemental uptake need to be investigated. • Valorization of organic waste is important to improve environmental sustainability through recycling of valuable waste. • Herein we investigated the potential applications of wood ash and paper sludge as a potting media for horticultural crops. • Wood ash and paper sludge improved the physicochemical properties of podzolic soil. • Paper sludge was more effective than wood ash in improving soil hydrological properties for better plant growth. • Furthermore, the incorporation of biochar in the potting media enhanced water holding capacity. [ABSTRACT FROM AUTHOR]

Water hyacinth (WH) is considered as the worst aquatic weed in the world because of its rapid growth and fast spread into new areas of fresh water bodies. We investigated the potentiality of using WH as a raw material for production of handmade paper and compost in Bangladesh. Potash pulping was done using potassium hydroxide (KOH) at different alkali concentrations (8–12%) with a liquor to solid ratio of 7:1 at 145 °C for 2 h. The pulp was bleached using hydrogen peroxide (H 2 O 2), and pulp properties (brightness, tear index and tensile index) of bleached and unbleached pulps were analyzed following the respective TAPPI standards. The produced black liquor was mixed with WH along with kitchen bio-wastes to produce compost. The properties of the compost were tested following the published protocols, i.e., wet digestion, Kjeldahl, vanadomolybdophosphoric acid, and Flame Spectrophotometry methods. Brightness, tensile index and tear index of bleached hand sheets were found to be 37.2%, 49.2 N m/g and 6.79 m.Nm2/g, respectively suggesting significant contribution of bleaching on WH paper quality. Addition of black liquor significantly increased the nitrogen and potassium content of bio-waste compost. Thus, WH can be used as a raw material for making handmade paper while the process by-product can be supplemented to improve the nutritional quality of compost. Such cottage-industry fabrication of WH green products could be developed to control the infestation of WH in water bodies, and this technology may provide for new possible sustainable livelihood option. [Display omitted] • Handmade paper was produced from water hyacinth (WH) using the KOH pulping method. • The waste potassium-rich black liquor was used to produce compost mainly from WH. • H 2 O 2 -bleached WH pulp showed better strength properties. • The produced compost was rich in macronutrients, i.e., N and K essential for plant growth. [ABSTRACT FROM AUTHOR]

A rapid upsurge in urban and industrial developments leads to increased generations of solid wastes. The most accepted technique of waste discarding around the world is landfilling. Leaching chemicals from municipal dumping grounds can pollute the groundwater source and the surrounding environment without appropriate precautionary measures. Bentonite is a low-cost constituent used as a liner material in landfills due to its low permeability, high sealing ability, high specific surface area, and the ability to hold up the impurity migration through adsorption. However, leachate interaction with bentonite may alter its properties and reduce its usefulness as a barrier material in the long term. Also, bentonite having different chemical and mineralogical compositions will behave differently due to the leachate interaction. Therefore, it is necessary to compare the performance of various bentonites in the presence of leachates. In the present investigation, two Indian bentonites of different mineralogical compositions were studied for their change in the index properties, swelling, swelling potential, swelling pressure, hydraulic conductivity, consolidation parameters and shear strength properties in the presence of fly ash, sewage sludge and paper mill leachates. The outcomes showed that in the presence of all the leachates, liquid limit, free swell, compression index, swelling potential, swelling pressure, time to complete 90% of consolidation and shear strength dropped; whereas, hydraulic conductivity and coefficient of consolidation increased. Besides, the quality of bentonite prominently influenced the hydraulic, strength and swelling behaviour. The bentonite having a higher cation exchange capacity, liquid limit, specific surface area, and swelling capability undergoes a higher variability in the free swell (80.0, 73.8 and 76.9% decline), liquid limit (73.5, 61.7 and 69.2% decline), swelling potential (61.3, 55.7 and 51.0% decline), swelling pressure (53.3 and 56.4% decrease), and hydraulic conductivity (57.5, 8.6 and 41.1 times increase at a void ratio of 1.2) values when infused with fly ash, sewage sludge and paper mill leachates, respectively. The study also showed that the fly ash leachate interaction causes a higher variation in bentonite behaviour than sewage sludge and paper mill leachates. The study's findings would prove beneficial to design engineers for selecting bentonite types for landfill liners. • Engineering properties of two Indian bentonites are presented. • Unconfined compressive strength reduced in the presence of all three leachates. • Hydraulic conductivity of the bentonites increased due to leachates. • Concentration level of metals and bentonite's composition greatly influenced engineering properties. • Influence of the fly ash leachate is the most among all three. [ABSTRACT FROM AUTHOR]

Sewer networks play a pivotal role in our everyday lives by transporting the stormwater and urban sewage away from the urban areas. In this regard, Sewer Overflow (SO) has been considered as a detrimental threat to our environment and health, which results from the wastewater discharge into the environment. In order to grapple with such deleterious phenomenon, numerous studies have been conducted; however, there has not been any review paper that provides the researchers undertaking research in this area with the following inclusive picture: (1) detailed-scientometric analysis of the research undertaken hitherto, (2) the types of methodologies used in the previous studies, (3) the aspects of environment impacted by the SO occurrence, and (4) the gaps existing in the relative literature together with the potential future works to be undertaken. Based on the comprehensive review undertaken, it is observed that simulation and artificial intelligence-based methods have been the most popular approaches. In addition, it has come to the attention that the detrimental impacts associated with the SO are fourfold as follows: air, quality of water, soil, and business and structure. Among these, the majority of the studies' focus have been tilted towards the impact of SO on the quality of ground water. The outcomes of this state-of-the-art review provides the researchers and environmental engineers with inclusive hindsight in dealing with such serious issue, which in turn, this culminates in a significant improvement in our environment as well as humans' well-beings. • A detailed scientometric analysis of the research carried out on sewer overflow hitherto is undertaken. • All different types of methodologies used in the previous studies are thoroughly investigated. • The aspects of environment impacted by the SO occurrence are reviewed. • The gaps existing in the relative literature together with the potential future works to be undertaken are put forward. [ABSTRACT FROM AUTHOR]

The traditional disposal methods of paper/wood industry raise serious environmental concerns, thus, requires innovative and productive ideas to manage such waste. This article deals with the appraisal and modification of lignosulphonate, a waste by-product of paper/wood industry, as a soil stabilizer to mitigate the disastrous environmental vulnerabilities of expansive soil related to the wetting-drying cycles. In this context, a novel approach of integrating lignosulphonate with hydrated lime was proposed, based on the short comings of lignosulphonate as a lone soil stabilizer. Periodic variations of wetting-drying cycles were assessed on various engineering properties of untreated and treated expansive soils with the optimum percentage of lignosulphonate, hydrated lime, and proposed binary admixture. Micro-fabric changes were also analyzed to evaluate the stabilization mechanism in mitigating the disastrous environmental aspects of expansive soil. The results showed that both untreated and lignosulphonate treated samples underwent suppression in swelling behavior and gain equilibrium at the third wetting-drying cycle. Whereas, the proposed binary admixture exhibited complete mitigation of the swelling behavior and showed significant hindrance against the wetting-drying cycles in terms of compressibility, hydraulic conductivity, and shear strength of soil. In comparison, lignosulphonate alone showed inferior and hydrated lime showed almost similar amelioration of most of the engineering properties accounting the environmental vulnerabilities of expansive soils. The scanning-electron micro-graphs of all the soil samples showed destructed clay structures with more inter assemblage pore spaces upon wetting-drying cycles. Moreover, the proposed binary admixture exhibited better stabilization mechanism than lignosulphonate alone considering the wetting-drying cycles. Evidently, the proposed binary admixture curtails the environmental vulnerabilities of expansive soil, significantly reduces the lime consumption for expansive soil stabilization, and proposes a sustainable and environment friendly waste management for the paper/wood industry. Image 1 • Traditional disposal methods of paper/wood industry raise environmental issues. • Paper/wood industry waste urges a sustainable use in construction industry. • Expansive soils are vulnerable to environmental changes i.e. wetting-drying cycles. • A new stabilizer is proposed by coupling paper/wood industrial waste with lime. • Comparative study of efficacy of proposed stabilizer, lignosulphonate and lime. [ABSTRACT FROM AUTHOR]

A long-term feasibility analysis of a 100 ton per day mechanical biological treatment (MBT) plant for municipal solid waste (MSW) valorization and material and energy recovery was carried out. It involves the material recovery and segregation stage (MRSS), organic extraction (pulping), thermophilic anaerobic digestion (AD), composting, effluent treatment plant (ETP), and biogas genset stages producing: 11.90% recyclables, 33% refused derived fuel (RDF), 5% compost of total waste received, 70 m3/day recyclable water and 0.435 MWh/day electricity. The biogas and methane yield were 0.535 and 0.350 m3/kg VS added (avg.), respectively, with 40% VS removal (avg total solids (TS) 10%). Less than 3% (inert) of total waste received was subjected to landfill disposal. The MBT plant's revenue generation is 995 US$ per day/148 tons ($ 6.72/ton) waste processed. The gross OPEX is 24 US$/ton making the net OPEX of 17 US$/ton (minus revenue), which could be considered as the excellent OPEX for MSW based MBT plants as per global benchmarks. Further, local usage of RDF can significantly reduce the OPEX to 14 US$/ton, as almost 16% of the OPEX goes towards RDF disposal to cement companies located at a distance of 200–500 km from the MBT plant site. As per LCA study, the total GHG emissions have been calculated to be −25.68 tons CO 2 eq./100 tons MSW. The negative emissions result from the export of electricity, compost, and RDF as well as recycling of paper and plastic products. Our study presents a cutting-edge scenario of all-inclusive recycling, recovery, and reuse loop of MSW direly required for accomplishing a circular economy. [Display omitted] • Long term performance of first successful 100 tons/d MBT plant in India was studied. • 12% recyclable, 33% RDF, 0.435 MWh/d power, 5% compost, 70 m3/d water were recovered. • Biogas and methane yield were 0.535 and 0.350 m3/kgVS added (65%CH 4), 40%VS removal. • MBT plant has OPEX of US$ 24/ton and revenue of $6.72/ton; net OPEX of US$ 17/ton. • LCA study revealed the negative GHG emission of −41.45 tons CO 2 eq./100 tons MSW. [ABSTRACT FROM AUTHOR]

This study investigated the dissolution of adhesive resins present in polyolefin films that cause plastic materials to adhere to each other. The process of dissolution was made by the use of ethyl acetate and followed by separation through the sink-float process. The objective was to separate and characterize polyolefin films from plastic solid waste derived from recycled post-consumer paper. Through these procedures, 6% polyethylene of high-density (HDPE), 14% polyethylene of low-density (LDPE) and 39% polypropylene (PP) were separated and recovered from plastic waste. Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analyzes (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) were conducted to determine the chemical, thermal and mechanical properties of the recovered polymers and to establish a comparison with standard commercial polymers. It demonstrated that recovered material kept their chemical, thermal, and mechanical properties. This process indicates possible economic viability considering the demand, the market value of the PP, and the required investment to be implemented in the recycling process that could be amortized in a short period of time. Moreover, the organic solvent used in the dissolution process can be easily recovered by distillation. Image 1 • A new approach to dissolution of adhesive resins with renewable solvent. • Polymeric waste from paper recycling process was separated through the sink-float. • Characterizations of separated and standard material have a satisfactory similarity. • The process proposed show economic viability. [ABSTRACT FROM AUTHOR]

Several countries have imposed either a ban or a tax on single-use plastic packaging, motivated by their contribution to marine plastic pollution. This may lead consumers to opt for similar unregulated substitutes, potentially undermining or even counteracting the intended effect of the policy instrument. The purpose of this study is to theoretically and empirically compare the environmental and welfare effects of the first-best Pigouvian taxes on both plastic bags and a substitute (paper bags), with two alternative second-best policy instruments: a tax on plastic products alone, and a common uniform tax on all packaging materials. The empirical analysis accounts for two different types of environmental externalities from the use of both bag types: marine pollution and greenhouse gas emissions. It also compares results for two countries, Denmark and the USA, which differ in the demand for plastic and paper bags. The theoretical analysis shows that a unilateral tax on plastic bags should equal the marginal environmental damage of plastic bags minus a fraction of the marginal environmental cost of paper bags, hence being lower than the Pigouvian tax. The optimal common tax should equal a weighted average of the marginal environmental damage of the two bag types and would be lower than the Pigouvian tax on plastics if the marginal external cost of plastic bags exceeds that for paper bags. The empirical analysis shows that for default parameters, the variation in tax level across the studied scenarios is small. It also shows that if Pigouvian taxes cannot be implemented, a common uniform tax on both bag types would result in a higher welfare gain than a tax on plastic bags alone. Sensitivity analysis reveals that the level of the second-best taxes and their associated environmental and welfare impacts are sensitive to assumptions regarding the littering rate and decay rate of plastic bags in the marine environment. • A separate tax on plastic bags leads to substitution towards unregulated products. • Both plastic bags and substitutes cause marine pollution and GHG emissions. • We estimate first and second-best environmental taxes on plastic and paper bags. • Pigouvian taxes on both plastic and paper bags yield the highest welfare effect. • A uniform tax on all bags yields higher welfare than a single tax on plastic bags. [ABSTRACT FROM AUTHOR]

Countries worldwide consider solid waste collection and recycling necessary due to the recent emphasis on conservation of resources and environmental protection. Due to the constraints from resource depletion and the need for sustainable economic growth, solid waste recycling has become a critical issue in China. Several indigenous researchers in China have studied the potential benefits of solid waste recycling. However, most studies limited the environmental assessment of solid waste recycling to greenhouse gas (GHG) emissions and considered only one type of solid waste (paper or plastic). Therefore, the present study analyzed the energy (electricity) and environmental (GHG and air pollutant emissions) benefits of recycling steel, nonferrous metal, plastic, and paper wastes from 2005 to 2017 in China. The study used the formulation of model equations method to estimate the electrical energy and environmental benefits. Prominent findings show that the total amount of electricity saved by recycling solid waste from 2005 to 2017 was 3743.3 Mtce. On average, solid waste recycling during the period led to a 43.2% saving on electricity. Solid waste recycling avoided 4765.9 billion kg of carbon dioxide emission and 22.502 billion kg of methane emission. It was also found that the recycling of solid waste saved a total amount of 10,669.8 M kg of NO X emission but had a burden of −6263.2 M kg of VOCs emission on the environment. Solid waste recycling avoided the emission of CO 2 , CH 4 , NO X , and SO X, but the recycling of steel, plastics, and paper waste had negative impacts on the environment in terms of VOCs and PM emissions. Proper measures such as installing air pollution control devices should be put in place to minimize the emission of pollutants during the recycling of these solid wastes. • The energy and environmental benefits of solid waste recycling is assessed. • The formulation of model equations method was used for the assessment. • On average, the recycling of solid waste saved 43.2% of electricity. • Recycling of waste avoided a significant amount of GHG and air pollutant emissions. • Solid waste recycling had no essential benefit on the emission of VOCs and PM. [ABSTRACT FROM AUTHOR]

The demand for paper and paper-based packaging has seen a massive increase in past years, resulting in accelerated deforestation to meet the rising demand, negatively impacting the environment, and there is a need to look towards different non-woody raw materials. Kraft pulping (KP) is widely used in paper making, for which the chemical dose, temperature, time, and energy required must be optimized, for which many insignificant experimental trials are performed. An effort is made to solve this problem by developing the regression equations with the help of Excel using One Factor at a Time Analysis (OFAT), followed by carrying out design of experiments (DoE) using orthogonal approach and regression analysis in Minitab software. Life cycle Assessment (LCA) using the Open-LCA software estimates the effect of chemicals and energy required during pulping on human health, ecosystem quality, and resource depletion. Using regression analysis, the equations for predicting kappa number, yield (%), total energy consumed, and mechanical properties of the paper sheet showed a good fit with an R2 value in the range of 0.90–0.99. Apart from that, the mechanical properties, namely tensile index (41.43 Nm/g), tear index (6.96 mN m2/g), bending stiffness (0.5 mN m), and burst index (3.92 kPa m2/g) of the unbeaten sheet, were determined experimentally at optimized conditions. Based on the Open-LCA result, the optimized pulping conditions had less impact on human health, ecosystem quality, and resource depletion. Industries can use the model to predict the values of kappa number, yield, mechanical properties, and energy consumption without performing optimization experiments that may impact the industry's economy to a greater extent. • Kraft pulping was chosen as pulping method for wheat straw. • The time, temperature and chemical dose were optimized for efficient and targeted kappa number, yield. • The regression equations for predicting mechanical properties and energy consumption of this process were developed. • The Life cycle assessment is done with respect to human health, ecosystem stability and resource depletion. • The mechanical properties of pulp are compared with BIS standards. [ABSTRACT FROM AUTHOR]

Abstract Marine sources especially crustaceans have been extensively used worldwide for the production of chitosan. However, limited availability as well as variations in the properties of the derived chitosan is a serious drawback of utilizing marine sources for chitosan production. This study investigated sustainable and green approach of fungal chitosan production using paper mill wastewater as a cheap and easily available substrate. The fungus Penicillium citrinum IITG_KP1 used in this study was initially isolated from an infected bamboo shoot. Addition of acetic acid at low levels led to a 150% increase in the yield of chitosan from 95 g/kg to 138 g/kg of dry fungal biomass. This result correlated well with an increase in xylose uptake rate due to acetic acid addition that was confirmed by enhanced activity of xylose reductase (XR) and xylitol dehydrogenase (XDH) enzymes in the presence of acetic acid. Very high COD removal efficiency (75%) along with 70% phenolic reduction and 84% decolourization efficiency of the raw paper mill wastewater without any prior pre-treatment was further achieved by carrying out the fungal fermentation using a bioreactor under batch mode of operation. The fungal chitosan showed properties comparable with those of a commercially available standard. Graphical abstract Image 1059 Highlights • Acetic acid induced chitosan production by P. citrinum biomass. • A novel method of fungal chitosan production using industrial wastewater is reported. • Batch mode of bioreactor operation is highly efficient for wastewater COD removal and chitosan production. • The fungal chitosan produced has properties comparable with those of the commercially available standards. [ABSTRACT FROM AUTHOR]

The rapid expansion of cities in developing countries has led to many environmental problems, and the mechanism of urban expansion (UE), as a more complex human-land coupled system, has always been a difficult issue to research. This paper introduces a new approach by establishing an analytical framework for spatiotemporal pattern mining, exemplified by studying the urban growth of Changsha City from 1990 to 2019. Initially, an emerging hotspot analysis model (EHA) is employed to examine the spatiotemporal changes of urban growth on a macro scale. Mathematical models are subsequently utilized to quantify the correlations between urban expansion and selected infrastructural and topographical factors. Building on these findings, the paper constructs mathematical models to further quantify the spatiotemporal evolution of various urban sprawl patterns across different regions, aiming to elucidate and quantify the significant variations in UE over time and space. The study reveals that, as an emerging city, Changsha's hotspots of urban expansion prior to 2003 were primarily concentrated in the city centre, subsequently spreading to the periphery. The radial influence of metro stations on UE is notably less than that of railway stations—approximately 3 km versus 8 km—and the impact diminishes rapidly before gradually tapering off. Moreover, UE in Changsha predominantly occurs on slopes with gradients ranging from 1.1° to 7.5°, and significant development capacity is observed at elevations between 36.1 m and 78.3 m above sea level, with a tendency for urban sprawl to migrate to lower elevations. The paper also identifies three distinct patterns of urban expansion across different regions: an initial slow-growth phase, followed by a rapid escalation to a peak, and subsequently a swift decline to near stagnation. Additionally, it highlights a significant correlation between the proportion of built-up areas at the micro-regional scale and the stages of UE. This correlation was quantitatively analysed by constructing a logistic function, which demonstrated a robust fit that effectively captures spatiotemporal heterogeneity in the dynamics of UE. These insights enhance the selection of drivers in urban simulation models and deepen the understanding of the complex dynamics that influence urban development. • New applications of spatiotemporal pattern mining and emerging hotspot analysis in urban expansion. • Exploring the impact of key infrastructure and topographical factors on urban expansion. • Focusing on revealing and quantifying the different inherent expansion mechanisms within various micro scales of cities. • The saturation of built-up areas in local regions correlates with the stages of urban expansion. [ABSTRACT FROM AUTHOR]

The development of digital finance provides new opportunities for improving energy efficiency and promoting green development. This paper calculates green total factor energy efficiency (GTFEE) using the super-efficiency SBM model and examines the impact of digital finance on GTFEE. Digital finance has a significant positive impact on GTFEE. Under a bank-dominated financial structure, the positive impact of digital finance on GTFEE is quite significant. In regions with intense banking competition, a large amount of green credit, and lower resource dependence, digital finance is conducive to enhancing GTFEE. Optimizing the allocation efficiency of production factors is an essential mechanism for digital finance to encourage improvements in GTFEE. Digital finance alleviates distortions in factor markets and enhances the matching of the marginal output and the price of capital, labor, and energy factors, thereby facilitating improvements in GTFEE. Further analysis indicates that digital finance has a significant, positive spatial spillover effect on GTFEE, enhancing GTFEE levels in both local and neighboring regions. This study enriches the research on the relationship between digital finance and energy efficiency and provides theoretical foundations and policy references for how digital finance can better serve the green transition of the economy. • This paper analyzes the impact of digital finance on green total factor energy efficiency (GTFEE). • Digital finance alleviates distortions in factor markets, thereby promoting GTFEE. • Digital finance's impact on GTFEE depends on financial structure, banking competition, green credit and resource dependence. • Digital finance has a significant positive spatial spillover effect on GTFEE. [ABSTRACT FROM AUTHOR]

Unlike most previous studies considering the yields on green bonds versus conventional bonds or the hedging ability of green bonds against downside market risk, the main purpose of this paper is to paper examine the short-term response of green and conventional bonds to the Russia-Ukraine conflict shock and the US Federal monetary policy tightening. Using daily data from August 3, 2021 to March 29, 2022, this paper conducts an event-based study (Cumulative Abnormal Returns, CAR) and then applies a hedging analysis in the context of increasing geopolitical risk and financial stress. The analysis reveals that green bonds exhibit a stronger reaction to the Russia-Ukraine conflict and the US Federal rate hike than conventional, municipal, and treasury bonds in different time frames. Compared to conventional, municipal, and treasury bonds, green bonds offer lower negative CAR responses during the event window and the [-5, +5] period, suggesting a rigidity feature. The dynamic correlation and hedging analysis indicate that green bonds, unlike the other bonds indices, have a negative dynamic correlation with both geopolitical risks and financial stress, implying a hedging ability around the conflict shock and the Federal tightening cycle. These findings enrich the existing literature on green bonds, offering a wide range of applications for investment managers and policymakers. • Use event-study, conditional correlation analysis, and hedging analysis. • Green bonds react more to Russia-Ukraine conflict and rate hikes than conventional bonds. • Green bonds offer lower negative CAR responses than conventional bonds. • Geopolitical risk and financial stress are negatively related to green bonds. • Green bonds hedge geopolitical risks and financial stress during the event days. [ABSTRACT FROM AUTHOR]

Submerged plants play a significant role in the remediation and purification of polluted water bodies. Reconstruction of submerged plants has been considered as an important ecological method to restore aquatic ecosystems. However, large-scale and efficient plantation of submerged plants in water restoration is a huge challenge. This paper proposes a novel mechanized planting method for submerged plants utilizing nutrition pots as planting units. Firstly, the details of the mechanized planting method were introduced. The mechanized planting method involves pre-planting the reproductive bodies of submerged plants in degradable nutrition pots, and then implanting them into the underwater soil through a planting device. Secondly, the interaction force between the nutrition pot and the soil was measured. It was found that the implantation force of nutrition pots increases with planting velocity. The planting force shows a significant increase trend when the water content in the soil decreases. Thirdly, the deformation of the nutrition pot was studied through simulations. It was discovered that the deformation of the nutrition pot mainly occurs at the bottom and the side walls near the bottom, and the limited deformation ensures the integrity of the nutrition pot. Finally, a planting device with a linear motion mechanism was designed, and a typical submerged plant, Vallisneria natans was tested, using agricultural paper seedling containers as the nutrition pots. It was demonstrated that the mechanized device successfully planted submerged plant nutrition pots into the soil, and the submerged plants survived and showed a clear growth trend. The mechanized planting method of submerged plants proposed in this article is expected to provide a new and friendly technology for ecological restoration of water source. [Display omitted] • A mechanized planting method for submerged plants in water ecological restoration is reported. • The interaction force between the nutrition pot and the soil was measured using force sensors. • A planting device was designed for the high-efficiency planting of submerged plants. • The planting method is expected to offer a technology for large-scale water ecological restoration. [ABSTRACT FROM AUTHOR]

The war in Ukraine has had a devastating impact on the environment. Military actions have caused the release of hazardous substances into the environment, such as pollutants and toxic chemicals, that have contaminated the water, soil, and air, posing a threat to both human health and the environment. This has resulted in widespread destruction and contamination of natural habitats and resources and has disrupted wildlife populations and ecosystems. The impacts of military activity on the soils of protected areas are particularly critical, as they are the basis of biotic and landscape diversity and require special management and scientifically based monitoring measures even in peaceful conditions. In this context, this communication paper aims to provide an overview of the impacts of the war on the soils in four Ukrainian protected areas, namely Chornobyl Radiation and Ecological Biosphere Reserve; Desniansko-Starohutskyi National Nature Park; Holosiivskyi National Nature Park, and Hetmanskyi National Nature Park. To address these aspects, this paper combined GIS analysis and secondary data including soil samples obtained during field expeditions, to provide evidence of how ground battles, occupation, terrestrial land mines, and explosions can severely impact the soils. Practical and theoretical implications of the military actions are also discussed. [Display omitted] • The research combined GIS analysis and secondary data including soil samples to provide evidence of war impacts in Ukraine. • This study discovered and discribed military actions that endangered environment of four protected areas in Ukraine. • On-site assessment of territories provided evidence of the destruction of soil horizons and alteration of their properties. • The soil sample analyses found that the protected areas are contaminated with hazard elements (I-III classes). • This study explored the interconnections of war and environmental degradation, and suggested mitigation measures. [ABSTRACT FROM AUTHOR]

Sewage sludge management is crucial for water utilities to move towards a circular valorisation of resources. The current literature focuses mainly on the technological aspects of sludge management strategies. However, the current discussion of these strategies does not consider possible pressures arising from the utilities' civil society stakeholders and from policymakers. To fill this gap, this paper develops a conceptual framework, based on the current literature, that identifies the utility's key decisions on sludge management strategies (valorisation route, overperformance and vertical integration), and links them to possible pressures arising from civil society and existing regulations. Subsequently, the study validates the framework through a multiple explanatory case study, investigating the empirical relevance of such pressures in six water utilities across Europe. The influence of citizens and municipalities is found to be crucial in the choice of sludge valorisation routes. Economic instruments, command and control instruments and, new to the literature, regulatory uncertainty are found to be key policy features influencing utilities' decisions on sludge management. The paper provides a first-of-its-kind investigation that highlights the mechanisms through which policymakers and civil society stakeholders shape utilities' sewage sludge management strategies. The results complement and extend existing theoretical knowledge on the role of institutional pressures in the implementation of sustainable environmental systems. • Stakeholders' influences on utilities' sludge management choices are conceptualised. • Policymakers and civil society influence utilities' sludge management choices. • Incentives, obligations, regulatory uncertainty shape sludge management choices. • Citizens and municipalities drive utilities' sludge management choices. • Utilities' characteristics moderate the impact of institutional influences on their choices. [ABSTRACT FROM AUTHOR]

This paper addresses the need to understand the structure of sustainability change in the face of the unpredictability of modern civilization. The aim of the paper is to examine the structure of sustainability change in relation to smaller spatial units such as the regions of the European Union and to compare these results with those achieved at the country level. For this purpose, the sustainable development indicators available in the Eurostat database were analyzed. Studies published to date have tended to focus on the performance of national economies or selected regions. In this article, the available data on regions are also analyzed. The study aims to compare the level of sustainable development achieved at the level of EU countries and regions located within them. Methodologically, the study uses advanced methods of comparative analysis, and the synthesis of the data enables the construction of a synthetic measure using taxonomic methods, facilitating the classification of EU countries and regions into clusters. The results highlight significant divergences in sustainability achievements between EU countries and regions. The study reveals the importance of studying sustainable development in smaller geographical cross-sections. The results highlight the need to expand access to data at the regional level (sustainability indicators) to facilitate more comprehensive analyses and inform targeted policy interventions. Looking to the future, the study recommends further research into the inter-linkages between sustainability and other critical areas in EU regions, such as innovation and competitiveness. • A new approach to studying sustainable development from a regional perspective has been proposed. • An in-depth analysis of the current level of sustainability in EU regions was carried out. • The diversity of sustainable development in the countries of the EU has been described. [ABSTRACT FROM AUTHOR]

In the context of China's efforts to combat climate change and promote sustainable development, the solid waste treatment industry's environmental, social, and corporate governance (ESG) performance is receiving significant attention. To comprehensively assess the ESG performance of the solid waste treatment industry and identify company types, this study constructs a targeted ESG evaluation index system based on existing literature, SASB industry standards, and company reports and utilizes a random forest approach combined with K-means clustering to determine indicator weights. Based on this index system, the paper evaluates the ESG performance of 71 solid waste disposal companies (SWDCs) from 2013 to 2021 and identifies their ESG types from static and dynamic perspectives. In the static view, company types are determined based on annual ESG performance, while the dynamic view considers time-series changes to observe the evolution of company ESG types. The results show that the overall ESG performance of SWDCs falls within the 2-8-point range, indicating a noticeable high-low imbalance. Key initiatives to improve ESG performance in this industry include enhancing waste management measures, developing emergency plans, and reinforcing ESG disclosure. From a static perspective, this paper can identify companies into three categories: delayed development, single-wheel-driven, and coordinated development. Finally, from a dynamic perspective considering the time factor, companies are further subdivided into five types: continual leading, growth catch-up, slow progress, fluctuating change, and retrogressive inertia. This study not only provides targeted recommendations for different types of ESG companies but also helps various sectors of society better understand the ESG conditions of this high environmental risk industry, thereby enhancing the regulation and support for its sustainable development. [Display omitted] • ESG evaluation index system for solid waste disposal companies is proposed. • A random forest method based on k-means clustering is used to construct the index. • Comparing E, S, and G scores with industry averages to identify static ESG types. • Analyzing trends in annual static ESG types to identify dynamic ESG types. • Identify companies as three static ESG types and five dynamic ESG types. [ABSTRACT FROM AUTHOR]