Paper Mill Sludge Research Articles

Potential pathway for reusing paper mill sludge ash as a supplementary material in alkali-activated bricks

Potential pathway for reusing paper mill sludge ash as a supplementary material in alkali-activated bricks

Valorization of paper-mill sludge laden with 2-chlorotoluene using hydroxyapatite@biochar nanocomposite to enrich methanogenic community: A techno-economic approach

While several studies have investigated the anaerobic digestion of paper-mill sludge (PMS), this technology suffers from nutrient insufficiency, inhibition by aromatic compounds, and low bio-CH4 yield. Hence, PMS was anaerobically co-digested with chicken manure (CM) and supplemented by hydroxyapatite@biochar (HAP@BC) nanocomposite for enhancing 2-chlorotoluene degradation and enriching the methanogenic archaea. Multiple continuous stirred tank reactors (CSTRs) were operated at 12.6 h hydraulic retention time (HRT), using PMS (R1), CM (R2), PMS + CM (R3), PMS + CM+100 mg HAP/L (R4), and PMS + CM+100 mg HAP@BC/L (R5). The maximum bio-CH4 yield of 147.5 ± 9.1 mL/g COD and 2-chlorotoluene removal of 91.2 ± 6.8 % were obtained from R5, experiencing a sufficient C/N ratio of 14.7 and the highest activities of acidogenesis (42.0 %), acetogenesis (37.9 %), and methanogenesis (42.1 %). The abundances of Euryarchaeota, Bacteroidota, and Chloroflexi at the phylum level, and Pseudomonas, and Bacillus at the genus level could highly contribute to the dechlorination mechanism and acetate transformation into CH4. This biomass-to-bioenergy project (10 m3/d capacity) could benefit from pollution reduction, biogas recovery, and carbon credit, giving 5.6 yr payback-period, 3503 USD net present value, and 12.1 % internal rate of return. Because R5 exhibited an efficient techno-economic anaerobic biodegradation performance, future studies are required to optimize its HRT condition and HAP@BC dosage.

The amendment value of pulp and paper mill sludges in Finnish coarse-textured soil

The amendment value of pulp and paper mill sludges in Finnish coarse-textured soil

DESIGN OF LANDFILLS AND THE UTILIZATION OF WASTES AS SUSTAINABLE LINER MATERIALS: A MINI-REVIEW

Modern landfills, designed to minimize environmental and health risks, play a crucial role in solid waste disposal. Poorly managed municipal solid waste facilities have severe environmental consequences, prompting intervention and remediation. Landfill construction is not enough; regular maintenance is essential to prevent harm. Landfills' historical evolution reflects societal needs, technological advancements, and environmental awareness. The 20th century saw engineered landfills with practices like compaction, daily covering, and leachate collection. Despite progress in recycling and incineration, landfills remain dominant, posing challenges like methane emissions, leachate contamination, and land use. Research emphasizes integrating landfills with recycling, composting, and waste-to-energy technologies for a sustainable future. Engineered landfills are advantageous over dumpsites, in terms of groundwater and air protection, odor control, energy generation, and job creation. Seismic analysis of landfills addresses deformation and seismic reactivity, emphasizing proper liner construction to reduce seismic impact. Leachate, a potential environmental hazard, requires careful management with effective liners to prevent groundwater and soil pollution. Various materials, including fly ash, paper mill sludge, waste foundry sand, recycled concrete aggregate, rice husk ash, and plastic waste, are reviewed for landfill liners. Research shows these materials can offer effective barriers, reducing environmental impact and promoting sustainability. Future studies should continue exploring alternative materials, considering factors like strength, hydraulic conductivity, and environmental protection.

Hazard reduction of heavy metals by co-pyrolysis of modified vermiculite with paper mill sludge/municipal solid waste: Characterization, risk and reaction mechanism study in pyrolytic environment

The increasing volume of paper mill sludge (PM) and municipal solid waste (MW) poses environmental problems associated with heavy metals. Co-pyrolysis of PM/MW with additives effectively reduces the risk of heavy metal contamination. In this study, co-modified vermiculite (LMV) was prepared using the modification methods of intercalation-exfoliation, Mg2+ impregnation, and thermal activation. PM and MW were mixed at different doping ratios, and a non-doping experiment was performed to compare the pyrolysis processes and the retention rates for different heavy metals (Zn, Cr, Cu, Cd, and Pb), as well as the potential ecological risks, and the form distribution of the heavy metals. The addition of LMV reduced the risk posed by heavy metals. In the absence of doping, a higher pyrolysis temperature is conducive to an increase in the oxidizable and residual fractions of heavy metals without higher retention rates. Among these heavy metals, Zn, Cr, and Cu had higher retention rates and low risks, whereas Cd had a relatively high risk with low retention rates. Simulations showed that there was a transfer of the Mulliken charge after the reaction, indicating that all the heavy metals can interact with O, Al, and Si in the LMV; this reaction mainly occurs around the No. 17 O atom of the LMV. The monomers, oxides, and chlorides of Zn/Cr/Cu exhibited better adsorption on vermiculite compared to that of Pb/Cd.

Upcycling Waste Biomass–Production of Porous Carbonaceous Supports from Paper Mill Sludge and Application to CO2 Conversion (Adv. Sustainable Syst. 8/2024)

Upcycling Waste Biomass–Production of Porous Carbonaceous Supports from Paper Mill Sludge and Application to CO₂ Conversion (Adv. Sustainable Syst. 8/2024)

Feasibility study of the paper sludge properties in manufacturing recycled filler

The mineralization of inorganic components in paper sludge offers potential for their re-use in various fields. This study synthesized carbonates based on the minerals present in paper sludge and aimed to investigate the control of particle size distribution and particle shape of the synthesized carbonates. First, the physicochemical and thermal properties of paper mill sludge and ash were evaluated using a spectrophotometer, XRF, and TGA. Paper sludge ash was obtained by incinerating the paper sludge, followed by a carbonation reaction using CO2 gas injection and pH neutralization to produce recycled fillers. The average particle size, crystal lattice structure, and morphology of the recycled fillers were analyzed using a particle size analyzer, XRD, and FE-SEM. The results indicate that the recycled filler produced from coating paper sludge exhibited similar brightness and morphology to conventional paper-based fillers, suggesting its potential to replace commercial PCC (Precipitated Calcium Carbonate). In contrast, the recycled filler manufactured using old corrugated container mill sludge was deemed unsuitable due to its low hydration activity.

Paper Mill Sludge as a Replacement for the Cellulosic Component of Hydroseed Mixtures

Paper Mill Sludge as a Replacement for the Cellulosic Component of Hydroseed Mixtures

Environmental and economic analysis of the transformation of paper mill sludge treatment technologies in China.

Paper mill sludge (PMS) is featured with a high content of cellulose and hemicellulose, and using its characteristics to make paperboard can achieve a high-value utilization of PMS, which has attracted growing interest. In this study, currently prevalent landfill, incineration technologies (generating heat and electricity by incineration), and three paperboard technologies (medium density fiberboard, pulp board, and corrugated paper) were evaluated and compared via life cycle assessment (LCA) and life cycle costing (LCC) methods. LCA results show that the PMS-to-pulp board outperforms others with an energy conservation and emission reduction (ECER) value of - 2.86 × 10-8, while the landfill exhibits the highest overall environmental impact with an ECER value of 4.80 × 10-9. LCC results reveal that the PMS-to-pulp board delivers the highest economic profit with $257.357, while the landfill is the lowest with $ - 35.63. The PMS paperboard technologies are more economically friendly than the incineration technologies due to additional electricity/steam consumption during the PMS pre-drying process in incineration. In addition, different scenarios were set up to explore national GHG emission reduction potential by increasing paperboard technologies application rate and reducing the proportion of landfill and incineration. The scenario analysis suggests that replacing 90% of landfill and incineration ratio with PMS paperboard technologies could tremendously improve the overall emission reduction performance with - 9.08 × 1010 kg CO2 eq. This result indicates that the PMS treatment technology transformation has a significant favorable impact on the achievement of the "carbon neutrality" target.

Upcycling Waste Biomass–Production of Porous Carbonaceous Supports from Paper Mill Sludge and Application to CO2 Conversion

AbstractThe urgent need for sustainable waste management strategies has led to the exploration of innovative approaches for the valorization of waste. In this study, a method is proposed for carbonizing waste biomass materials, particularly paper mill waste sludges (primary and biological) and knots, to produce porous carbonaceous supports. Through an initial hydrothermal carbonization followed by carbonization with nitrogen flow, porous carbon materials are successfully generated. The findings of this investigation validate the successful generation of effective carbonaceous supports utilizing waste biomass materials. These materials are then evaluated for their effectiveness as porous supports in the ionic liquid‐catalyzed cycloaddition reaction of CO2 to styrene oxide, achieving a remarkable conversion rate of up to 98% and an impressive selectivity exceeding 99%. Additionally, the results underscore the significant impact of the selected IL on the overall conversion process. Overall, this study presents a promising pathway for the valorization of paper mill waste sludge through the production of porous carbon materials with potential applications in catalysis and beyond.

Cradle-to-grave environmental and economic sustainability of lime-based plasters manufactured with upcycled materials

The production of CaO for lime-based plaster and render generates 1.2 t CO2/t CaO, consumes 1.78 t CaCO3/t CaO. This research paper examines the environmental and economic performance of upcycling paper mill sludge (PMS) and carbide lime (CL) as replacements for hydrated lime (HL) in lime-based plasters production. For this, a new Cradle-to-Gate industrial-scale inventory is designed, upscaling recent lab-scale innovations, investigating PMS and CL treatment processes, followed by a Cradle-to-Grave scenario analysis. The results show that incorporating CL in the plaster yields better environmental and economic outcomes compared to PMS. The intermediate treatment for CL is cost-effective and has low carbon emissions. The upcycling of CL eliminates 100% of CO2 emissions, while PMS reduces emissions by 11%. The production of the traditional binder HL is more expensive than upcycling PMS (+69%) and CL (+65%), with carbon taxes accounting for 35%, 44% and 15% of production costs, respectively. The effect of an equilibrated carbon price to ensure fair market competition, considering the natural carbonation of lime (carbon credit) is discussed, and the cost assessment reveals a 47% and 54% reduction for upcycled plasters using PMS and CL, respectively, compared to traditional HL.

The influence of biochar from animal and plant on the transformation of phosphorus during paper mill sludge composting.

Biochar has effect on phosphorus adsorption, release, and transformation. This study compared the influence of biochar derived from animal (AB) and plant (PB) during paper mill sludge composting. Results indicated AB not only accelerated sludge decomposition but also had significantly higher levels of available phosphorus (AP) than PB and CK (no biochar), with AP contents in the order of AB > PB > CK. Compared to CK, AB was found to increase the relative abundance of thermophilic bacteria, and PB diversified the microbial community. Based on Pearson and RDA results, TOC/TN ratio (C/N) and organic matter (OM) explained above 50% of the variance in microbial community and phosphorus fractions. Thermophilic bacteria with high levels of OM and C/N promoted the conversion among labile and moderately labile organic phosphorus, moderately labile inorganic phosphorus, and AP. Biochar could enhance the AP conversion pathway, leading to increased levels of AP.

Effect of the reactor heating rate on bio-crude yield and quality from hydrothermal liquefaction of different sludge

This study scrutinizes the effect of the heating rate obtained in two reactors of different volume (10 mL and 500 mL) on the production of bio-crude during the hydrothermal liquefaction (HTL) process applied to sludges of different nature: a municipal, a paper mill and an agricultural sludge. The effect of the reactor scale on the chemical composition of the bio-crude and the solid residue (co-product of HTL process) is also evaluated by elemental, GC–MS and FT-IR analysis. Results suggest that different heating rates along HTL exert an almost negligible influence on the bio-crude yield and limited effect on the chemical composition when the reaction time under the isothermal conditions is kept at 10 min. In fact, regardless of the heating rate, the bio-crude yields on dry basis from municipal, paper mill and agricultural sludges are equal to 21 %, 21 % and 12 %, respectively. These results could be explained with the different reactive pathway and kinetics of the sludges macro-components.

Fast co-pyrolysis of paper mill sludge and corn stover: Relationships between parameters, product distributions, and synergistic interactions

The co-pyrolysis of paper mill sludge (PS) and biomass has attracted significant attention due to its potential for simultaneous resource utilization and waste disposal. In this work, the co-pyrolysis of PS with corn stover (CS) was carried out in a fixed bed reactor to investigate the effect of temperature and PS to CS ratio on the product characteristics. A comparison between the experimental and calculated values of product yield and composition was performed to obtain a deeper understanding of the synergistic interactions. The results exhibited a positive synergistic effect on bio-oil production at lower CS proportions with higher temperatures. Higher temperatures and lower CS proportions were favorable for the formation of aromatics (up to 45.03%) in co-pyrolysis, while the synergistic interactions promoted the production of phenols and exhibited an inhibitory effect on aromatics production. The interactions also inhibited H2 but promoted CO production due to the enhanced decarbonylation of co-pyrolysis intermediates in the presence of PS internal minerals. Additionally, the characterization of biochars indicated an increasing degree of aromaticity with higher temperatures and CS proportions. The synergistic interactions at higher temperatures facilitated the development of pore structures in the biochar, especially micropores. This study provides valuable insights into the relationship between parameters, products, and synergies in the co-pyrolysis of PS and biomass wastes.

Comprehensive kinetic modeling and product distribution for pyrolysis of pulp and paper mill sludge

Pyrolysis holds immense potential for clean treatment of pulp and paper mill sludge (PPMS), enabling efficient energy and chemical recovery. However, current understanding of PPMS pyrolysis kinetics and product characteristics remains incomplete. This study conducted detailed modeling of pyrolysis kinetics for two typical PPMSs from a wastepaper pulp and paper mill, namely, deinking sludge (PPMS-DS) and sewage sludge (PPMS-SS), and analyzed comprehensively pyrolysis products. The results show that apparent activation energy of PPMS-DS (169.25–226.82 kJ/mol) and PPMS-SS (189.29–411.21 kJ/mol) pyrolysis undergoes significant change, with numerous parallel reactions present. A distributed activation energy model with dual logistic distributions proves to be suitable for modeling thermal decomposition kinetics of both PPMS-DS and PPMS-SS, with coefficient of determination >0.999 and relative root mean square error <1.99 %. High temperature promotes decomposition of solid organic materials in PPMS, and maximum tar yield for both PPMS-DS (53.90 wt%, daf) and PPMS-SS (56.48 wt%, daf) is achieved at around 500 °C. Higher levels of styrene (24.45 % for PPMS-DS and 14.71 % for PPMS-SS) and ethylbenzene (8.61 % for PPMS-DS and 8.33 % for PPMS-SS) are detected in tar and could be used as chemicals. This work shows great potential to propel development of PPMS pyrolysis technology, enabling green and sustainable production in pulp and paper industry.

Direct generation of high-valent iron-oxo species to eliminate oxytetracycline at circumneutral pH via paper mill sludge ash activating peroxymonosulfate

The excellent performance of high-valent iron-oxo species (FeIVO) in the degradation of pollutants by activating peroxymonosulfate (PMS) had attracted much attention. However, the generation and reaction mechanisms were still unclear. In this study, iron-rich paper mill sludge was used as a raw material for the first time to prepare iron-based catalysts with abundant octahedral FeIII sites (FeoctIII). The results showed that the highest content of FeoctIII was found in the paper mill sludge ash obtained by aerobic calcination at 800 °C (pmSA800), and the pmSA800 could exhibit excellent catalytic activity (0.4785 min−1) and stability during the oxytetracycline (OTC) degradation process. The characterization and density functional theory (DFT) calculations further indicated that the FeoctIII was the dominant active site for FeIVO production. PMS tended to be adsorbed on two adjacent FeoctIII sites to form a [FeoctIII-OSO2OO(H)-FeoctIII] complex with a two-site adsorption configuration. Subsequently, the OO and OH bonds in [FeoctIII-OSO2OO(H)-FeoctIII] broken by absorbing energy, generating FeIVO. It's worth noting that the Ca species of pmSA800 effectively stabilized the pH of the reaction solution, which ensured the stable and continuous production of FeIVO. This work provides a new idea and insight for preparing catalysts that could produce FeIVO active species.

Effective stabilization of heavy metals in solid waste and sludge pyrolysis using intercalated-exfoliated modified vermiculite: Experiment and simulation study

Pyrolysis is effective in reducing the volume of solid waste and sludge, and produces less pollutants than incineration and landfill, but the process still suffers from heavy metal pollution. Four types of intercalated-exfoliated modified vermiculite (UIV, DIV, TIV and 3IV) were prepared using urea, dimethylsulfoxide, tributyl phosphate and 3-aminopropyltriethoxysilane as intercalators for the control of Cd, Cr, Cu, Pb and Zn in municipal sewage sludge (MSL), paper mill sludge (PML), municipal domestic waste (MWA) and aged refuse (AFE). The larger the interlayer spacing of the vermiculite, the more favorable the retention of heavy metals. 3IV was the most effective additive, with an average retention of more than 75 % of all heavy metals at 450 ℃ for the four raw materials. Cr, Cu, Pb and Zn were all at low potential ecological risk (Pr), while Cd was moderate or considerable Pr, and the addition of 3IV reduced the Pr. Distribution of intercalators between vermiculite interlayers was haphazard, and interlayer spacing results were close to those of the experiment (except for tributyl phosphate). The reactive electrons mainly flowed from the Highest Occupied Molecular Orbital (HOMO) of vermiculite flakes to the Lower Unoccupied Molecular Orbital (LUMO) of heavy metal chlorides. In contrast, the reactive electrons mostly flowed from the HOMO of heavy metal oxides to the LUMO of vermiculite flakes. Heavy metal oxides were more readily adsorbed on vermiculite flakes than heavy metal chlorides, and the adsorption capacity of Cr and Zn was stronger than that of Cd, Pb and Cu.

Waste to functions: Construction of a novel solar-thermal conversion material based on sludge-derived carbon dots via Ca-in-situ-functionalization for efficient solar-driven water evaporation

Solar interface water evaporator (SIWE) based on waste-derived carbon dots (CDs) are highly promising for large-scale production applications in the future, due to their low-cost, eco-friendly, and tunable structure and properties. However, there are still obstacles, including limited performance, blind selection of waste materials, and unknown underlying mechanisms between waste properties and the physicochemical properties of derived CDs. In this study, a novel CDs-based wooden SIWE derived from paper mill sludge (PMS) was constructed (called ESCDs-wood). Under 1 sun, ESCDs rapidly heated up from 15.6 °C to 53.5 °C and reached stability within 10 mins. The solar-thermal conversion efficiency of ESCDs was as high as 137.58 %, and the ESCDs-wood achieved a high evaporation rate of 2.94 kg m-2h−1. Moreover, the ESCDs-wood cost about $9 to complete 1 m2 evaporation. Meanwhile, the ESCDs-wood exhibited long-term stability, after 20 cycles, its solar-thermal conversion efficiency and water evaporation rate remained at 84.21 % and 85.03 % of the initial test, respectively. Moreover, the Ca-doping was found to be a key factor in effectively enhancing the solar-thermal conversion and the thermal stability of ESCDs, and the exact role of Ca-doping on the solar-thermal conversion performance enhancement of CDs was validated and revealed. Therefore, this study not only constructed a cost-effectiveness, high performance, sustainability, chemical-free, and eco-friendly SIWE, but also innovatively proposed the functionalization mechanism of Ca-doping for CDs and thus provided a new sight for the targeted regulation and design of CDs.

Production of Fe-biochar from paper-mill sludge and its application to Se(VI) and Se(IV) removal

This study aimed to fabricate zero-valent iron (Fe0)-loaded biochar from an industrial waste and further demonstrate its applicability as an environmental medium to remove Se(VI) and Se(IV). The biochar (PS/BC-750) was produced via the pyrolysis of paper-mill sludge under N2 atmosphere. The characterization revealed that PS/BC-750 has a porous carbon structure embedded with reduced Fe phases (Fe0 and FeO). The adsorptive removal of Se(VI) and Se(IV) by PS/BC-750 was highly dependent on pH condition and progressively decreased with the pH increase. The adsorption kinetics of Se(VI) and Se(IV) reached equilibrium within 1440 and 60 min, respectively, following a pseudo-second-order kinetics. Se(VI) and Se(IV) adsorption isotherms fit to the Freundlich and Langmuir models, respectively, highlighting the importance of chemisorption in the adsorption processes. X-ray photoelectron spectroscopy and competing anions experiments revealed that Se(VI) was adsorbed mainly on the Fe phases while Se(IV) was adsorbed on both Fe phases and carbon surface by specific binding mechanisms, with those adsorbed on Fe phases being subsequently reduced to Se0. The results demonstrated that the pyrolytic process can be of a viable platform for converting Fe-containing waste materials into environmental media with a wide application potential.

A Fixed Bed Adsorption Column Study for Synthetic Dye Wastewater using Magnetic Biochar

The study aimed to investigate the performance of a fixed bed column using magnetic biochar as an adsorbent for synthetic dye wastewater treatment. The magnetic biochar was synthesized by pyrolyzing paper mill sludge at 350 ℃ and modified with iron oxide nanoparticles to enhance its magnetic properties. The adsorption capacity of the magnetic biochar was evaluated using methylene blue (MB) dye in wastewater. In present study the fixed bed column adsorption was conducted using MBC to treat MB wastewater. A fixed bed column setup was utilized in the experiments, maintaining a continuous flow rate of 15 mL/min at various bed height (i.e. 2.5, 5 &amp; 7cm). Breakthrough &amp; exhaustion capacity for each three different bed height at constant flow rate was also carried out. The Yoon-Nelson and Thomas kinetics models were also used in order to understand the dynamic performance of the fixed bed column. the respectively. The results shows that Yoon-Nelson model fitted best for the experimental data approximately R2 value of 0.96 against Thomas model R2 value of 0.95. Hence, it can be concluded that fixed bed column with MBC performed best with higher bed height &amp; adsorption process is limited by film &amp; pore diffusion