scholarly journals A. Leshchinskaya. MICROWAVE WOOD CHIP TREATMENT USE IN CHEMICAL PULP MANUFACTURING (TECHNICAL-ECONOMIC ASSESMENT)

2019 ◽  
Author(s):  
Alexandra Leshchinskaya
Keyword(s):  
Wood Chip ◽  
Pulp Mill ◽  
Pulp Mills ◽  
Technology Application ◽  
Capital Costs ◽  
Pulp Industry ◽  
Chemical Pulp ◽  
Chip Processing ◽  
Electricity Costs ◽  
Treatment Use

MICROWAVE WOOD CHIP TREATMENT USE IN CHEMICAL PULP MANUFACTURING   (TECHNICAL-ECONOMIC ASSESMENT)   A. Leshchinskaya   Plekhanov Russian University of Economics. 36 Stremyannyy Pereulok, 115093 Moscow, Russia, e-mail: [email protected]]   Keywords: chemical pulping, microwave wood modification, pulp, softwood, wood chips.   Large volumes of cellulose are produced from wood chips by chemical methods. Low permeability of many wood species causes problems in the chemical pulp industry. These include: very long cooking times, high chemical consumption, large material losses, high energy consumption, and environmental pollution. New microwave (MW) wood modification technology can provide an increase in wood permeability for liquids and gases, which solves many of these problems. The technology works  by applying intensive MW power to green wood, which generates steam pressure within wood cells. High internal pressure destroys weak elements of wood structure, opens pores and forms micro and macro cracks. A several thousand-fold increase in wood permeability can be achieved in species previously found to be impermeable to liquids and gases. It allows a significant increase in the speed of pulp cooking and improves a production processes. The study of the technology showed radical potential improvements in the pulp industry through: increase in mill throughput significant reduction of chemical consumptionreduction of energy consumption •     increase in pulp quality and yield improvement of environmental performance.   Pulp manufacturing process includs timber chipping, microwave chip treatment, steaming, cooking, washing, and pulp making. The use of MW wood chip treatment in pulp mills with outputs of 50,000 to 500,000 air dry tons (ADT) per year requires MW equipment with power from 1000 to 10,000 kW. Economic modelling of this technology used in different pulp mill conditions allowed assessment of the effect of capital costs, electricity costs, labour costs and other cost components to specific total costs of MW chip processing. Economic assessment of MW technology application showed that specific costs of softwood chip processing at electricity costs of 0.08 - 0.12 US$/kWh are 25.4 -33.7 US$/ADT of pulp. Electricity costs form the most significant part of the total specific costs of MW processing and form 51-69% shear in the total specific costs. Under the same conditions capital costs form 15-20% shear, and labour costs form 5-18% shear of the total specific costs. The electricity cost increase from $0.04 to $0.24/kWh provides specific MW processing cost rise by 2.7 to 3.1 times at pulp mill output range 50,000 to 500,000 ADT/year. New technology use allows benefits up to 7 – 22 Mil US$ per year for pulp mills with output of more than 200,000 ADT/year. The technology can be used by pulp mills with batch and continuous digesting and is not limited by mill throughput. Ecological impacts and high economic advantages of this MW technology application in pulp and paper industry provide good opportunity for commercialisation.  

scholarly journals Hydrothermal Carbonization of Chemical and Biological Pulp Mill Sludges

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5693
Author(s):  
Clara Lisseth Mendoza Martinez ◽  
Ekaterina Sermyagina ◽  
Esa Vakkilainen
Keyword(s):  
Driving Forces ◽  
Pulp Mill ◽  
Value Added ◽  
Carbonaceous Material ◽  
Hydrothermal Carbonization ◽  
Organic Substrates ◽  
Pulp Mills ◽  
Pulp Industry ◽  
Liquid Products ◽  
Pulp Mill Sludge

A modern pulp mill generates a variety of different by-products and waste streams, some of these can be recycled, refined, sold, or used on-site for energy production. However, some, such as chemical and biological sludges produced in wastewater treatment cannot be reused or disposed of easily, mainly due to their high moisture content and poor drying characteristics. Tightening legislation regarding waste disposal as well as the growing need to increase the process efficiencies of pulp mills act as driving forces to find environmentally friendly and energy-efficient techniques for pulp mill sludge treatment. This study summarizes the current methods for pulp mill sludge handling and evaluates the potential of hydrothermal carbonization (HTC), a conversion process through which wet organic substrates can be transformed into a carbonaceous material (hydrochar). Depending on the process parameters, the material’s structure is modified, enabling hydrochar use in energy, soil conditioning and adsorption applications. The sludges were hydrothermally carbonized at 180, 200, 220 and 240 °C for 3 h. The hydrochar and liquid products’ main properties were analyzed. Their potential applications were also evaluated. The effective treatment of sludges from the pulp industry with HTC could transform energy-demanding waste into a value-added source of materials.

Biological treatment and ultrafiltration of woodchip pre-hydrolysis liquor from dissolving pulp mills

2018 ◽  
Vol 33 (2) ◽  
pp. 358-364
Author(s):  
Tatiana Aurora Condezo Castro ◽  
Claudio Mudadu Silva ◽  
Jorge Luiz Colodette ◽  
Ann H. Mounteer
Keyword(s):  
Energy Demand ◽  
Biological Treatment ◽  
Black Liquor ◽  
Hydrothermal Process ◽  
Treatment Plant ◽  
Wood Chip ◽  
Oxygen Demand ◽  
Pulp Mill ◽  
Pulp Mills ◽  
Treated Effluent

Abstract Dissolving pulps could be considered as the future biorefineries, which normally generate liquor during the wood chip pre-hydrolysis (PHL). PHL has high chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Mills do not have efficient means for disposal of PHL, being in general burned in the recovery boiler with a high cost due to its low consistency. The objectives of this work were to evaluate i) the biotreatability of PHL and the effects it would have on a kraft mill effluent biological treatment plant and ii) the use of ultrafiltration (UF) membrane to treat the PHL prior to biological treatment. PHL was generated into lab with a hydrothermal process and was mixed with kraft pulp mill effluent in different proportions and added to sequencing batch reactors (SBRs). The SBRs achieved high rates of COD removal (>75 %). However, treated effluent COD increased with the increase in PHL dose. This treatment using UF membranes reduced the COD load. Biotreatability of the UF permeate was higher than that of PHL. UF retentate, with 28 % of the volume and a much higher solids content than the initial PHL, would have a significantly lower evaporation energy demand if sent to the black liquor evaporators.

Activated sludge plants in Finland

1997 ◽  
Vol 35 (2-3) ◽  
pp. 235-243 ◽  
Author(s):  
R. Saunamäki
Keyword(s):  
Activated Sludge ◽  
Pulp Mill ◽  
Paper Mill ◽  
Pulp Mills ◽  
Nitrogen And Phosphorus ◽  
Paper Mills ◽  
Effluent Concentration ◽  
Chemical Pulp ◽  
Treated Effluent ◽  
Low Load

The performance of Finnish activated sludge plants (primary clarifier, equalization basin, buffer basin, aeration basin, secondary clarifier and sludge handling) was surveyed. Performance was generally found to be excellent. BOD7 removal averaged 94% at paper mills (21mg/l effluent concentration, 0.43 kg/t discharge) and 95% at chemical pulp mills (18 mg/l, 0.83 kg/t). CODCr removal averaged 82% at paper mills (158 mg/l effluent concentration, 3.52 kg/t discharge) and 60% at pulp mills (531 mg/l, 20.7 kg/t). Treated effluent from paper mills contained 0.57 mg/l (13.3 g/t) of total phosphorus and from pulp mills 1.31 mg/l (47.3 g/t). AOX removal was 45-65% and discharge 0.15-0.90 kg/t. Suspended solids removal averaged 91% at paper mills and 76% at pulp mills, the average overflow concentration in primary clarifier being about 150 mg/l at both types of mill. All activated sludge plants are designed according to either the low load or extended aeration principle; high load plants are no longer in use. The average sludge load was 0.15 kg BOD/(kg MLSS d), the sludge age at the extended aeration plants ranging from 20 to 50 d. Low load appearance to be the main reason for the good performance of the plants. Other factors included the introduction of equalization and buffer basins at many plants, and particularly the fact that aeration factors and nutrients were under control. All paper mill activated sludge plants use nitrogen and phosphorus additions, whereas pulp mill plants manage without phosphorus. Optimization of nutrient addition is vital because almost every mill in Finland has a limit for its phosphorus discharge. Total sludge production at the paper mill plants averaged 40.9 t/d, 15% of which (5.9 t/d, 6.0 kg/t) was biosludge. At the pulp mills the figures were 27.2 t/d (11.5 t/d biosludge, 9.5 kg/tp). Belt filter presses are used for dewatering at most plants and dry solids contents are usually 25-35%. New-generation screw presses have been introduced, mainly at new pulp mill activated sludge plants, yielding dry solids contents of 40%. Combined and dewatered sludge is normally burned in bark-fired boilers, although some mills still landfill their sludge.

Requirements for the Treatment of Effluents from Chemical Pulp Mills in the F.R.G.

1988 ◽  
Vol 20 (1) ◽  
pp. 19-24 ◽  
Author(s):  
L. Huber ◽  
H. Baumung
Keyword(s):  
Biological Treatment ◽  
Pulp Mill ◽  
Pulp Mills ◽  
Pollution Levels ◽  
Chemical Pulp ◽  
Elemental Chlorine ◽  
Minimum Requirements ◽  
High Pollution ◽  
Sulfite Pulp ◽  
Spent Liquor

In 1986, the 11 chemical pulp mills in the F.R.G. produced 350,00 t of bleached sulfite pulp. With the enactment of the so-called minimum requirements in 1982, general standards for the treatment of effluents were promulgated for this branch of industry. They comprise various measures, such as high-grade recovery of spent liquor including its evaporation and incineration, partial or total reuse of condensates from evaporation or reduction of their load by stripping, and mechanical treatment of total waste water. In view of the persisting high pollution levels of German rivers caused by pulp mills, more stringent standards reflecting the present state of the art will be implemented in 1991. This paper deals with these standards, covering the applicable in-plant and external abatement measures, such as extended cooking, substitution of elemental chlorine and biological treatment for decisive improvement of the chemical pulp mill effluent situation.

Fate of phosphorus in the recovery cycle of the kraft pulping process

TAPPI Journal ◽  
2020 ◽  
Vol 19 (3) ◽  
pp. 139-148
Author(s):  
MARYAM SADEGH MOUSAVI ◽  
NIKOLAI DEMARTINI
Keyword(s):  
Kraft Pulp ◽  
Pulp Mill ◽  
Field Studies ◽  
Kraft Pulping ◽  
Pulp Mills ◽  
Recovery Cycle ◽  
Green Liquor ◽  
Green Liquor Dregs ◽  
Kraft Pulp Mills ◽  
Negative Effect

The accumulation of nonprocess elements in the recovery cycle is a common problem for kraft pulp mills trying to reduce their water closure or to utilize biofuels in their lime kiln. Nonprocess elements such as magne-sium (Mg), manganese (Mn), silicon (Si), aluminum (Al), and phosphorus (P) enter the recovery cycle via wood, make-up chemicals, lime rock, biofuels, and process water. The main purge point for these elements is green liquor dregs and lime mud. If not purged, these elements can cause operational problems for the mill. Phosphorus reacts with calcium oxide (CaO) in the lime during slaking; as a result, part of the lime is unavailable for slaking reactions. The first part of this project, through laboratory work, identified rhenanite (NaCa(PO4)) as the form of P in the lime cycle and showed the negative effect of P on the availability of the lime. The second part of this project involved field studies and performing a mass balance for P at a Canadian kraft pulp mill.

Pulp mill process closure: a review of global technology developments and mill experiences in the 1990s

2004 ◽  
Vol 50 (3) ◽  
pp. 183-194 ◽  
Author(s):  
S.C. Stratton ◽  
P.L. Gleadow ◽  
A.P. Johnson
Keyword(s):  
Manufacturing Industry ◽  
Pollution Prevention ◽  
Optimal Solution ◽  
Pulp Mill ◽  
Thermomechanical Pulp ◽  
Pulp Mills ◽  
Oxygen Delignification ◽  
Manufacturing Operations ◽  
The Impact ◽  
Mill Process

The impact of effluent discharges continues to be an important issue for the pulp manufacturing industry. Considerable progress has been made in pollution prevention to minimize waste generation, so-called manufacturing “process closure.” Since the mid-1980s many important technologies have been developed and implemented, many of these in response to organochlorine concerns. Zero effluent operation is now a reality for a few bleached chemi-thermomechanical pulp (BCTMP) pulp mills. In kraft pulp manufacturing, important developments include widespread adoption of new cooking techniques, oxygen delignification, closed screening, improved process control, new bleaching methods, and systems that minimize pulping liquor losses. Coupled to this is a commitment to reduce water use and maximize reuse of in-mill process streams. Some companies pursued bleach plant closure, and many have been successful in eliminating a portion of their bleaching wastewaters. However, the difficulties inherent in closing bleach plants are considerable. For many mills the optimal solution has been found to be a high degree of closure coupled with external biological treatment of the remaining process effluent. No bleach plants at papergrade bleached kraft mills are known to be operating effluent-free on a continuous basis. This paper reviews the important worldwide technological developments and mill experiences in the 1990s that were focused on minimizing environmental impacts of pulp manufacturing operations.

Purification of pulp mill condensates by an adsorptive process on activated carbon

Holzforschung ◽  
2019 ◽  
Vol 73 (6) ◽  
pp. 589-597 ◽  
Author(s):  
José A.F. Gamelas ◽  
Sofia M. Rebola ◽  
Margarita G. Evtyugina ◽  
Valdemar I. Esteves ◽  
Dmitry V. Evtuguin
Keyword(s):  
Activated Carbon ◽  
Volatile Compounds ◽  
Water Cycle ◽  
Black Liquor ◽  
Pulp Mill ◽  
Dimethyl Disulfide ◽  
Pulp Mills ◽  
Wide Range ◽  
New Process ◽  
Pseudo Second Order

Abstract In order to close the water cycle in pulp mills with condensates instead of fresh water, the malodorous/hazardous volatile compounds and colored substances have to be removed by appropriate efficient methods. In the present work, the condensate from the evaporation of black liquor (BL) from a kraft mill was purified by a batch adsorptive process by means of commercial activated carbon (AC). The effluent was found to contain a wide range of aromatic and organosulfur volatile compounds, including toluene, ethylguaicol, syringaldehyde, dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), 2,3-dimethylthiophene, benzothiol and benzothiophene derivatives. Methanol was the major volatile organic component in the condensate (201 mg l−1), which was, however, poorly adsorbed on the AC surface. Aromatics and organosulfur contaminants were adsorbed almost completely in 2–5 min at 23°C under the optimized AC load (900 mg l−1). The treatment allowed the elimination of up to 99% of the obnoxious odor, color and turbidity of the condensate. The adsorption equilibrium followed the Langmuir model and the pseudo-second-order kinetics. The new process could be incorporated in the pulp mill with relatively low additional reagent costs.

scholarly journals Method for analysis of ClO2 and Cl2 air emissions from pulp mill

2019 ◽  
Vol 34 (1) ◽  
pp. 19-27
Author(s):  
Kimona Häggström ◽  
Magnus Gunnarsson ◽  
Katarina Bremert-Jirholm ◽  
Nina Simic
Keyword(s):  
Chlorine Dioxide ◽  
Analytical Method ◽  
Kraft Pulp ◽  
Pulp Mill ◽  
Air Emissions ◽  
Pulp Mills ◽  
Limit Of Quantification ◽  
Regulatory Standards ◽  
Low Concentrations ◽  
Kraft Pulp Mills

Abstract Chlorine dioxide is commonly used as a bleaching agent in kraft pulp mills. Scrubbers are required to remove any remaining ClO2 from the plant tail gases. To control the air emissions of chlorine compounds, chlorine dioxide and chlorine contents must be monitored to ensure that the strict regulatory standards are met. However, the currently used analytical method is not suitable for detection of low concentrations of chlorine and chlorine dioxide. A new method for measuring chlorine dioxide and chlorine emissions was developed, which ensures compliance with the stringent requirements imposed by the authorities. The two species could be measured separately with a limit of quantification of 3 ppm. The method was robust and easy to use in the pulp mill environment and it was validated both in the laboratory and the field. The specificity of the method was demonstrated, Cl2 analysis was not sensitive to the presence of ClO2 and vice versa. The uncertainty (±2×RSD) of the analytical method in the field was estimated from duplicate measurements performed in the range of 3–500 ppm for ClO2 and 3–300 ppm for Cl2, and was found to be ±20 % and ±10 %, respectively. Possible interferences in the analytical method are also discussed.

scholarly journals New alternative energy pathway for chemical pulp mills: From traditional fibers to methane production

2017 ◽  
Vol 235 ◽  
pp. 265-273 ◽  
Author(s):  
Lourdes Rodriguez-Chiang ◽  
Kari Vanhatalo ◽  
Jordi Llorca ◽  
Olli Dahl
Keyword(s):  
Methane Production ◽  
Alternative Energy ◽  
Pulp Mills ◽  
Chemical Pulp

Differential recovery of δ13C in multiple tissues of white sucker across age classes after the closure of a pulp mill

2014 ◽  
Vol 71 (5) ◽  
pp. 747-755 ◽  
Author(s):  
T.J. Arciszewski ◽  
A.J. Farwell ◽  
M.R. Servos ◽  
T.D. Jardine ◽  
K.R. Munkittrick
Keyword(s):  
Muscle Tissue ◽  
Pulp Mill ◽  
Pulp And Paper ◽  
White Sucker ◽  
Pulp Mills ◽  
Age Classes ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Gonad Tissue ◽  
Age Range

Techniques to document recovery after the closure of pulp mills that discharge enriching effluents are not well established, but δ13C may be a useful tool. In the 1990s, the muscle tissue of white sucker (Catostomus commersonii) collected downstream of two pulp and paper mills discharging into separate streams (Mattagami and Kapuskasing rivers) was enriched in 13C compared with upstream fish, suggesting uptake of pulp-derived C. The Mattagami River mill was closed in 2006, and analysis of muscle and gonad for δ13C was performed in 2011. As expected, fish captured in 2011 downstream of the operational Kapuskasing mill still showed the influence of the pulp-derived C in muscle and gonad tissue. After the closure of the Mattagami River mill, muscle tissue of white sucker was still enriched in 13C compared with upstream fish, while gonad tissue was not. The patterns observed in the Mattagami River were, however, related to age; the oldest fish showed enrichment of δ13C in both muscle and gonad tissue, suggesting the residual occurrence of pulp-derived C. This study suggests that measurements of stable isotopes in fish across a broad age range may indicate ecosystem improvements. These techniques may also be useful where no data prior to the upgrade or closure are available for comparison.

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