Pulp Mill Research Articles

Utilization of pretreated green liquor dregs as an activator for blast furnace slag: Effect on hydration, phase assemblage, and rheology

This study explores the utilization of calcium- and magnesium-rich pulp mill residues, i.e., green liquor dregs (GLDs), as an activator for ground granulated blast furnace slag (BFS). The aim of this study is to examine the potential of this unutilized residue when used as a part of alkali-activated materials (AAMs) and in this way enhance the exploitation of GLD. This study focuses on the fresh- and hardened-state properties of the produced paste and mortar samples, where 70% of BFS and 30% of GLD have been incorporated. Two different-sourced and thermally pretreated (105 °C, 300 °C, and 525 °C) GLDs have been used. The effect of thermal treatment on the utilization possibility of GLDs with respect to viscosity, setting times, reactivity, mineralogy, and microstructure is analyzed using the paste samples, while its effect on workability, and strength gain is measured using the mortar samples. Results show that both GLDs enhance the hydration of BFS and that the early-age hydration and strength increase when the GLDs have undergone pretreatment at the highest temperature (525 °C). However, at the later age (28 days), the samples activated with the GLDs treated at 300 °C achieve the highest strength. The addition of both GLDs treated at any temperature increases the viscosity of the composite samples and reduces their workability; however, it should be noted that optimization of water to binder ratio was not the objective of this study. The results of this study show that GLD, previously considered unreactive, can potentially become a reactive component of AAMs.

Assessment of solar drying of Brazilian pulp mill primary sludge

AbstractPulp mill sludge is a challenging by-product in wastewater treatment plants (WWTP), due to high moisture content, and poor dewatering characteristics. Solar drying was identified as an appropriate pre-treatment to reduce sludge moisture and enhance its energy efficiency for combustion purposes. Brazil is the world’s second-largest pulp producer, and its high intensity of annual solar irradiation makes it a prime candidate for the application of solar sludge drying technology. This study evaluates the main characteristics of primary sludge (PS) from pulp mills at 65% and 95% moisture content. An active passive solar dryer, followed by ASPEN Plus software simulation was used to evaluate drying properties and combustion potential. CO2 emission impact was explored, and the environmental effects of primary sludge combustion after solar drying were estimated. As indicated by the findings, the sludge commenced with a solids concentration of 21%, eventually reaching 95.5%, thereby enhancing its suitability for combustion. From the simulation, a heat rate expenditure in sludge combustion reported 24672 kW and 16295 kW for a solids content of 65% and 95%, respectively. Therefore, employing solar drying before the sludge incineration is crucial for minimizing energy consumption during combustion. Additionally, solar energy being cost-free, offers an opportunity to alleviate environmental harm.

Assessment of Aerotechnogenic Effects of Industrial Emissions of Arkhangelsk Pulp аnd Paper Mill by Bioindication Method

Assessment of the aerotechnogenic impact of the Arkhangelsk Pulp and Paper Mill on the environment was carried out. It is based on an analysis of the functional stability of representative bioindicator objects according to a set of biochemical parameters: enzymatic activity, content of phenolic compounds and ascorbic acid. The urbanized territory was mapped according to the degree of influence of the APPM on the components of forest ecosystems in accordance with the tendency of accumulation of sulfur compounds as marker pollutants of emissions of Pulp and Paper Mills. By the correlation analysis, it was shown that changes in the biochemical parameters of bioindicator objects are the manifestation of adaptive responses to the multifactorial effects of anthropogenic, technogenic and climatic impacts.

Metagenomes and metagenome assembled genomes from anaerobic digesters at three Canadian pulp and paper mills.

We present a dataset of six metagenomes and 323 metagenome assembled genomes (MAGs) describing the microbial community of anaerobic digesters at three Canadian pulp and paper mills. Our objective was to assess the coding potential of the microbial community and obtain draft genomes of key organisms in the digesters.

Robust scheduling of a pulp and paper mill considering flexibility provision from steam power generation

The production scheduling and flexibility provision analysis are of great importance for industrial facilities to provide support for the main power grid. This study proposes a comprehensive scheduling model for an industrial pulp and paper (P&P) mill that considers the flexibility provision from steam power generation. In this model, the internal relationships between the production and consumption of electricity, steam, and pulp in the operational processes of the P&P mill are investigated. Meanwhile, the available flexibility of steam power generation is quantified and further enhanced for participation in the manual frequency restoration reserve (MFRR) market. Furthermore, a robust scheduling model that uses support vector clustering (SVC) technology is proposed to assess the impact of uncertainties in steam temperature and pressure on the available flexibility of steam power generation, thereby reducing the probability of failing to provide the contracted flexibility for MFRR. Simulation results demonstrate that the comprehensive scheduling model significantly increases the available flexibility of steam power generation for MFRR, resulting in a daily revenue increase of $1839.8. Moreover, a balance between the revenue obtained from the MFRR market and the probability of economic penalties incurred for failing to meet the contracted flexibility is achieved by comparing different levels of conservatism in the robust scheduling model.

Xanthan gum templated hydrothermal synthesis of Bi2O3 nano-photocatalyst for the mineralization of chlorophenols prevalent in paper pulp mill

Xanthan gum templated hydrothermal synthesis of Bi2O3 nano-photocatalyst for the mineralization of chlorophenols prevalent in paper pulp mill

The role of the pulp and paper industry in achieving net zero U.S. CO2 emissions in 2050

The pulp and paper industry is energy-intensive, making up about 9 % of total United States industrial energy consumption and 2.5 % of U.S. industrial greenhouse gas emissions. The pulp and paper industry is unique among industrial sectors due to its existing reliance on waste biomass to generate energy for mill operations. Pulp and paper mills could theoretically offer opportunities for negative emissions through carbon capture and storage (CCS) technologies along with use of biomass. In addition, the paper sector's use of low-temperature industrial heat creates opportunities for CO2 reductions through electrification technologies.We employ the Global Change Analysis Model (GCAM) to evaluate decarbonization pathways for the pulp and paper sector in the United States, as well as the sector's role in a net zero scenario and impacts on the energy, land, and water sectors. The version of GCAM used in this study includes detailed representation of major industrial sectors, including the pulp and paper industry. Representation of the linkage between forest products and paper production allow us to account for upstream carbon emissions, sequestration, and land-use impacts.Preliminary results under a pathway to net zero U.S. CO2 emissions in 2050 show that the pulp and paper industry can reach net zero CO2 emissions before 2050, earlier than the overall energy system, and contribute negative emissions thereafter. Use of fossil fuels is significantly reduced by 2050, shifting to increased electricity use in process heat generation. Consumption of biomass energy in process heat also increases compared to the reference scenario. Though paper production decreases in the policy scenario in response to higher prices of wood products, a high carbon price can incentivize increased use of biomass with CCS and thus paper production. Negative emissions opportunities in the paper industry have impacts on the land sector. Increasing use of biomass accelerates the shift from unmanaged to managed forests, with associated tradeoffs between technological carbon sequestration and natural ecosystem services.

Effect of treating birch kraft pulp with peracetic acid before O2-delignification on the properties of pulp and consumption of ClO2 in D0ED1 bleaching

The influence of pre-treating Kappa number of 18.0 industrial birch kraft pulp with peracetic acid (Paa) before oxygen delignification (OD) was studied relative to the pulps’ level of delignification, yield, brightness, intrinsic viscosity (IV), FS-number, tear index (TI), and the consumption of chlorine dioxide (ClO2) in its subsequent Elemental Chlorine Free (ECF) bleaching. The study showed that such pretreatment is a way to extend the delignification of such pulp quite selectively in OD based on values of IV, FS-number, and TI, and to reduce significantly the consumption of ClO2 required to bleach this pulp to a brightness of 87%. This reduction depended on the amount of Paa used for pulp pretreatment. For example, when 0.33% and 0.66% as active oxygen (A.O.) of Paa were used, ClO2 consumption to bleach the pulp to 87% was lowered by 15.4% and 42.3%, respectively. As high as a 61.5% reduction in ClO2 consumption in its bleaching could be obtained using 0.66% as A.O. on pulp and change of time of OD. This result allows for a significant decrease in the chlorine passing to the filtrates from washing the pulp after the D0 and E stages to the pulp mill wastewater treatment plant.

Ecological and Geochemical Assessment of the State of Soils in the City of Baikalsk According to the Content of Polycyclic Aromatic Hydrocarbons

The pollution of the topsoils of the city of Baikalsk (Irkutsk region) under the influence of industrial emissions and wastes of the Baikal Pulp and Paper Mill (BPPM) was studied. The content of 16 individual PAH structures in samples of urban and background soils taken during the soil geochemical survey in the summer of 2019 was analyzed. Relatively low levels of PAH content were found in the lignin sludge from the BPPM and СHP ash. The concentration of total PAHs in CHP ash reaches 46 mg/ kg with a predominance of low molecular weight compounds (the proportion of naphthalene and its homologues is 24% and 34% of the total PAHs, respectively), among high molecular weight PAHs, 5-nuclear benzo(b)fluoranthene dominates (16%). In lignin sludge, the amount of PAHs is 7.16 mg/kg with the predominance of benzo(b)fluoranthene (83%). In the soils of Baikalsk, the average total content of PAHs (38.4 mg/kg) is 5 times higher than the background content. In urban soils, 4–5-nuclear fluoranthene (61.1%) and benzo(b)fluoranthene (29.4%) prevail. This makes it possible to attribute soil pollution to the fluoranthene type. The soils of the motor transport (total PAH 105 mg/kg) and industrial (59.5 mg/ kg) zones are the most polluted, where the most contrasting PAH anomalies were formed. In descending order of the amount of PAHs, the land use zones of the city form a series: motor transport industrial residential one-storey railway transport residential multi-storey recreational zone. Several local anomalies in the amount of PAHs are distinguished, forming two large pollution halos in the western and eastern parts of the city. The leading factors in the accumulation of high molecular weight PAHs in soils are acid-alkaline conditions and soil organic matter, while the accumulation of low molecular weight polyarenes is mainly controlled by pH. The environmental hazard of pollution of Baikalsk soils with polyarenes is due to benzo(b)fluoranthene, its contribution is 83.5%.

Energy saving potential in steam systems: A techno-economic analysis of a recycling pulp and paper mill industry in Morocco

The industrial sector represents nearly 40 % of global energy consumption, with steam systems accounting for 30 % of energy use in manufacturing. As the need for cleaner processes intensifies within African and global energy transitions, adopting energy efficiency practices becomes imperative. Governments are focusing on reducing energy losses in fossil fuel-dominated manufacturing industries, which are major producers of greenhouse gas emissions. Despite their significant energy consumption, industrial heat processes are often overlooked in efforts to reduce costs and emissions. To address this, the study examines thermal energy processes and identifies energy-saving opportunities within steam systems through a techno-economic analysis of a recycling pulp and paper mill in Morocco. This is the first study focusing specifically on steam systems within a particular industry in the country. The research uses a system approach covering steam generation, distribution, end-use, and recovery. The current system is benchmarked through a rating questionnaire, and proposed energy-saving actions include leak repair, pipe insulation, blowdown management, and improved boiler combustion efficiency. An economic study evaluates the cost-effectiveness of these opportunities. Findings reveal a 6 % reduction in thermal energy consumption, annual savings of $417 899 and nearly 482 TJ, a 6 % decrease in GHG emissions (2158.5 tons of CO2 per year), and water savings of approximately 5300 m³ per year (13 %). The total investment of $8750 has negligible payback periods. Despite diverse industrial activities, this work is useful for other industries since the fundamental components of the steam system are widely shared. Moreover, it supports the African Union's Agenda 2063 and United Nations Sustainable Development Goals by providing practical insights and recommendations for enhancing industrial energy efficiency.

Identifying Applications of Wood Ash by Matching Its Characteristics with End-User Quality Requirements: A Case Study

Despite being a bio-based material, wood ash generated by pulp and paper mills is mainly landfilled in Canada. This is because it is perceived as waste material and the certification requirements and regulations controlling its use are complex. To promote wood ash utilization, ash samples from mills in British Columbia (BC), Canada were characterized, and the properties were compared to quality specifications for potential applications. Three types of ash samples were collected: bottom ash, multi-clone (MC) ash, and electrostatic precipitator (ESP) ash. The characteristics of each type of ash were analyzed, and their suitability for various applications was determined. The study found that ESP ash had a higher calcium carbonate equivalent (CCE) value than MC ash, making it more useful as a liming material in agricultural land. The study identified quality criteria for industries where wood ash can be used, such as construction, agriculture, composting, stabilization/solidification, liming, mining, and fire-retardant. Each type of ash was evaluated for its use in these industries, and the environmental regulations for each application were considered. It was observed that the quality criteria for one application could differ dramatically from those for another. Intuitively, an ash producer would cross-check the characteristics of their ash types against the quality requirements for potential uses near the ash source because different applications have different quality requirements This article is believed to help identify promising applications of ash thereby removing ash from landfilling and promoting the circular economy.

Treatment of pulp and paper mill effluent through combined aerobic and anaerobic suspended fixed-bed bioreactor.

This study explored using ultrafiltration (UF) membranes to treat pulp and paper mill wastewater, implementing a novel Taguchi experimental design to optimize operating conditions for pollutant removal and minimal membrane fouling. Researchers examined four factors: pH, temperature, transmembrane pressure, and volume reduction factor (VRF), each at three levels. Optimal conditions (pH10, 25°C, 6bar, VRF 3) led to a 35% reduction in flux due to fouling and high pollutant rejections: total hardness (83%), sulfate (97%), spectral absorption coefficient (SAC254) (95%), and chemical oxygen demand (COD) (89%). Conductivity had a lower rejection rate of 50%. Advanced imaging techniques like atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed reduced membrane fouling under these conditions. The Taguchi method effectively identified optimal conditions, significantly improving wastewater treatment efficiency and promoting environmental sustainability in the pulp and paper industry. PRACTITIONER POINTS: This study optimized UF membrane conditions for pulp and paper mill wastewater, reducing fouling and enhancing pollutant removal, offering practical strategies for industrial treatment. AFM and SEM provided key insights into membrane fouling and mitigation, promoting real-time diagnosis and optimization for enhanced treatment efficiency. Prioritizing anaerobic fixed-bed systems in wastewater treatment is beneficial for achieving high COD removal efficiency. Optimizing hydraulic retention time (HRT) in these systems can further improve their overall effectiveness and sustainability.

Sulfur makeup in an unbleached kraft pulp mill

Sulfur makeup in an unbleached kraft pulp mill

Optimisation of Water-Use in Pulp and Paper Mills: A Streamlined Review of Scientific Journal Publications

The water-, and energy footprints of the processes in the pulp and paper industry are sizable enough to warrant investment of money and commitment of time truncate the same. Besides, there is also a nexus between water and energy here, with optimisation of the use of one of these resoruces enabling that of the other too. This streamlined review focuses on journal publications (originating from different parts of the world, and targeted at researchers and decision-makers in the industry) which train the lens on the optimisation of water use in this particular sector of the (forestry) bioeconomy. The synergies and complementarities which exist among different sustainable development goals (SDGs) , promise positive ripple effects, caused by attending to the truncation of the water footprint. The articles, in general, recommend effective in-plant wastewater treatment in combinaton with recirculating the treated effluent, and looking upon the water streams as carriers or bearers of valorisable substances – organics which can yield a host of bio-products in bio-refineries, including bio-energy. Availing of water-pinch analysis as a tool to uncover possibilities of water use in a cascade (depending upon the requirements imposed on the water, by processes downstream in the cascade), has been shown to aid in the optimisation of both water use and energy demand within the plant. One case study, for example, showed that the demand for steam can be decreased by about 4 GJ per ton of output, by recovering the waste heat in the water streams.

Hybrid solar drying of sludge from kraft pulp mills

Abstract Sludge generated from kraft pulp mill wastewater treatment plants (WWTPs) is typically non-inert solid waste and is commonly disposed of in landfills. In this study, a novel approach for repurposing WWTP sludge from a kraft pulp mill in Brazil for energy generation was assessed. With the global cellulose market projected to reach $ 61 billion by 2033, there is a growing need for sustainable energy solutions and disposal of associated industrial byproducts. This study investigated the performance of a hybrid active solar dryer for reducing the moisture content of sludge to enhance the feasibility of sludge burning in a biomass boiler. Through rigorous experimentation and design of experiments (DOE) planning, optimal parameters for the hybrid dryer were determined, specifically, a volumetric airflow rate of 1.1 m/s and an entrance temperature of approximately 51 °C. This innovative approach not only addresses the environmental concerns associated with sludge disposal, but also contributes to the broader goal of advancing sustainable technologies in the midst of global energy challenges.

Lignin extraction in chemical pulp mills: The role of flexible operation

Lignin extracted from black liquor in chemical pulp mills can potentially replace fossil carbon feedstocks in fuels and materials, thereby increasing the economic and environmental added values of woody biomass. However, since lignin extraction reduces the electricity generation of the mill, the added value depends on the characteristics of the electricity market in which the mill operates. In this study, a model mill is exposed to two different electricity price profiles: the low and steady prices of south-central Sweden in Year 2019; and the high and volatile prices of the same region in Year 2022. For the model mill, investments in lignin extraction designed to increase pulp production are economically viable and have low levels of sensitivity to electricity price levels and price volatility. The viability of lignin extraction without increased pulp production depends on the relationship between the electricity and lignin prices. With stable electricity prices, or steady mill operation, a rule-of-thumb holds that for lignin extraction to be viable, the lignin price (€/t) must be 1.8-times the average electricity price (€/MWh) plus 40 €/t for the supply of chemicals. With volatile electricity prices and flexible operation of the recovery boiler, the mill can shift the loss in electricity sales to low-price hours, thereby saving 15–70 % of the operational costs of lignin extraction, as compared to steady operation. This effect can be further enhanced by increasing the capacity of the lignin extraction process or extending the size of the black liquor storage tank. The proposed flexibility measures allow the market-integrated pulp mill to export lignin to replace fossil carbon supplies in other sectors, while supporting the electricity system during hours with high demand and low supply.

ОПРЕДЕЛЕНИЕ ФИТОТОКСИЧНОСТИ СУБСТРАТОВ НА ОСНОВЕ ОТХОДОВ АКТИВНОГО ИЛА В ВЕГЕТАЦИОННЫХ ОПЫТАХ

The aim of the study is to determine the phytotoxicity of components and substrates using waste from the treatment facilities of the Arkhangelsk Pulp and Paper Mill. The substrates were made on the basis of high-moor peat with a decomposition degree of 15 %, with the addition of Biohumus Arkhangelsky, which is composted residual activated sludge from treatment facilities (RAS). To test extracts from materials used to prepare experimental substrates, oats (Avena sativa L.) and watercress (Lepidium sativum L.) were used. Comparison was carried out with distilled water and Knop's mixture. To select the optimal ratio of residual activated sludge and peat for plant growth, a model experiment was conducted with growing oats. The substrates prepared by the volume of fractions with a gradation of activated sludge of 10 % were studied. It was found that composted activated sludge does not have phytotoxicity in relation to the test objects. The extract based on dewatered activated sludge of the treatment facilities of the Arkhangelsk Pulp and Paper Mill does not have a depressing effect on the germination of test objects – oat and watercress seeds, and according to the indicators of the length of the root and coleoptile of oats, it has a stimulating effect comparable to or exceeding the effect of the Knop mixture. Phytostimulating effect of peat extract was not detected. The addition of OAI to high-moor peat during the preparation of substrates has a positive effect on growth indicators. An increase in the length of the stem and root, the mass of the underground and aboveground parts of plants is noted. The optimal addition to the substrate for growing oats is composted activated sludge in the amount of 10–20 %. With large proportions of composted activated sludge waste (more than 40 %), oat growth decreases, but the mass of stems and roots increases.

Effect of incubation conditions of cellulase hydrolysis on mechanical pulp fibre morphology

The mechanical pulp industry is diversifying through the manufacture of high-value paper products, such as microfibrillated cellulose. However, the development of fibre quality is still energy-intensive. Enzymatic hydrolysis is hypothesized to promote fibre cutting, greater fibrillation, and reduce refining energy costs. Despite potential benefits, there is little understanding of the mechanisms behind fibre development during enzymatic hydrolysis of mechanical pulp. This work investigates how incubation pH and temperature during enzymatic hydrolysis impact the refining of mechanical pulp short fibres. Incubation with endoglucanase at pH 5 and 60 °C increased fibre cutting by approximately 20 %. Fibrillation was negatively affected at this condition, resulting in increased slim fines formation with refining. Incubation at pH 8 and 80 °C promoted >15 % reduction in fibre length, despite such conditions being associated with low enzyme activity. The pH variation modified the sedimentation height of the fibres and the conductivity of suspensions, indicating a change in fibre surface charge. Fibre morphology changes were induced by enzyme hydrolysis conducted at conditions representative of the full range of pH and temperature observed in mechanical pulp mills.

Leaching phosphorous from the lime mud of kraft pulp mills: Towards sustainability

AbstractThe optimum conditions needed to separate phosphorus from the lime mud generated in kraft pulp mills were identified using different leaching solutions including carbonate, bicarbonate, and green liquor under variety of conditions. Carbonate ions seemed to be the active ion in the phosphorus leaching process. Bicarbonate solution seems to be the most effective leaching agent by removing 84% of phosphorus under the optimum operating conditions of 95°C, 2.92 m, and solution‐to‐ mud mass ratio of 3.6. The shrinking core model was used to determine the leaching mechanism and it showed that the leaching process is controlled by a mix of chemical reaction and diffusion through the particle. Two empirical models were developed to predict the leaching efficiency as a function of carbonate concentration and temperature. Counter‐current leaching was shown to be beneficial in increasing the leaching efficiency with the carbonate solutions.

Comparison of thermal, rheological properties of Finnish Pinus sp. and Brazilian Eucalyptus sp. black liquors and their impact on recovery units

Black liquor (BL) is the major bioproduct and biomass fuel in pulp mill processes. However, the high viscosity of BL makes it a challenging material to work with, resulting in issues with evaporators and heat exchangers during its transport and processing. The thermal and rheological properties of BLs from Pinus sp. (PBL) and Eucalyptus sp. (EBL) were studied. FTIR spectra revealed the presence of the characteristic functional groups and the chemical composition in liquors. TGA/DTG curves showed three characteristic degradation stages related to evaporation of water, pyrolysis of organic groups, and condensation of char. Rheologically, liquors are classified as non-Newtonian and with comportment pseudoplastic. Their rheological dynamic shear properties included a linear viscoelastic region up to 1% shear strain, while frequency sweeps showed that storage modulus (Gʹ) > loss modulus (Gʹʹ), thus confirming the solid-like behavior of both BLs. The rheological study demonstrated that increasing the temperature and oscillatory deformations of PBL and EBL decreased their degree of viscoelasticity, which could favor their pumping and handling within the pulp mill, as well as the droplet formation and swelling characteristics in the recovery furnace.