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Phiri, J., Ahadian, H., Sandberg, M., Granström, K. & Maloney, T. (2023). The Influence of Physical Mixing and Impregnation on the Physicochemical Properties of Pine Wood Activated Carbon Produced by One-Step ZnCl2 Activation. Micromachines, 14(3), Article ID 572.
Open this publication in new window or tab >>The Influence of Physical Mixing and Impregnation on the Physicochemical Properties of Pine Wood Activated Carbon Produced by One-Step ZnCl2 Activation
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2023 (English)In: Micromachines, E-ISSN 2072-666X, Vol. 14, no 3, article id 572Article in journal (Refereed) Published
Abstract [en]

In this study, two different sample preparation methods to synthesize activated carbon from pine wood were compared. The pine wood activated carbon was prepared by mixing ZnCl2 by physical mixing, i.e., "dry mixing" and impregnation, i.e., "wet mixing" before high temperature carbonization. The influence of these methods on the physicochemical properties of activated carbons was examined. The activated carbon was analyzed using nitrogen sorption (surface area, pore volume and pore size distribution), XPS, density, Raman spectroscopy, and electrochemistry. Physical mixing led to a slightly higher density carbon (1.83 g/cm(3)) than wet impregnation (1.78 g/cm(3)). Raman spectroscopy analysis also showed that impregnation led to activated carbon with a much higher degree of defects than physical mixing, i.e., I-D/I-G = 0.86 and 0.89, respectively. The wet impregnated samples also had better overall textural properties. For example, for samples activated with 1:1 ratio, the total pore volume was 0.664 vs. 0.637 cm(3)/g and the surface area was 1191 vs. 1263 m(2)/g for dry and wet mixed samples, respectively. In the electrochemical application, specifically in supercapacitors, impregnated samples showed a much better capacitance at low current densities, i.e., 247 vs. 146 F/g at the current density of 0.1 A/g. However, the physically mixed samples were more stable after 5000 cycles: 97.8% versus 94.4% capacitance retention for the wet impregnated samples.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
pine wood, supercapacitor, activated carbon, biomass, energy storage, carbonization, physical mixing and impregnation
National Category
Materials Chemistry Bio Materials
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-94375 (URN)10.3390/mi14030572 (DOI)000958964100001 ()36984979 (PubMedID)2-s2.0-85152213764 (Scopus ID)
Available from: 2023-04-20 Created: 2023-04-20 Last updated: 2024-01-17Bibliographically approved
Mohammadi, A., Anukam, A. I., Granström, K., Eskandari, S., Zywalewska, M., Sandberg, M. & Aladejana, E. B. (2022). Effects of wood ash on physicochemical and morphological characteristics of sludge-derived hydrochar pellets relevant to soil and energy applications. Biomass and Bioenergy, 163, Article ID 106531.
Open this publication in new window or tab >>Effects of wood ash on physicochemical and morphological characteristics of sludge-derived hydrochar pellets relevant to soil and energy applications
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2022 (English)In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 163, article id 106531Article in journal (Refereed) Published
Abstract [en]

Hydrochar is produced through a process called hydrothermal carbonization (HTC) and constitutes a carbon-rich solid material with different remarkable applications. This study investigated the effects of wood ash on the physicochemical and morphological properties of biosludge-derived hydrochar in pelleted form relevant to the use of the pellets as a soil nutritional and liming agent and as a biofuel source. The hydrochar was mechanically compressed into uniformly-sized pellets under applied pressures of 4 and 8 kN after blending with varying percentages of wood ash in the order 0, 20 and 50%. The pure and blended pellets were characterized to determine the impact of wood ash on key properties, correlated to the two applications mentioned above. Results demonstrated a strong relationship between key features of the pellets and ash proportion. The wood ash-blended hydrochar pellets showed good hydrophobicity as a consequence of increased contents of alkali and alkaline earth metals, but were low in aromatic functional groups compared to the pure hydrochar pellet. Furthermore, the heating value of the pure hydrochar pellet was about 4% higher than that of its parent material and indicates that this pellet has the capacity to serve as a source of energy. The study generally reveals that blending hydrochar produced from biosludge under HTC conditions with up to 20%–50% of wood ash and mechanically compressing into homogeneous pellets has promising potential for a nutrient-rich material that can enhance soil fertility.

Place, publisher, year, edition, pages
Taylor & Francis, 2022
Keywords
Scanning electron microscopic analysis, Elemental composition, Enrichment, Soil amendment, Heating value
National Category
Environmental Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-91366 (URN)10.1016/j.biombioe.2022.106531 (DOI)000831133900003 ()2-s2.0-85134298843 (Scopus ID)
Funder
ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 19-622
Available from: 2022-07-17 Created: 2022-07-17 Last updated: 2022-10-13Bibliographically approved
Mohammadi, A., Govindarajan, V., Sandberg, M., Eskandari, S., Joseph, S. & Granström, K. (2020). A Comprehensive Environmental Life Cycle Assessment of the Use of Hydrochar Pellets in Combined Heat and Power Plants. Sustainability, 12(21), Article ID 9026.
Open this publication in new window or tab >>A Comprehensive Environmental Life Cycle Assessment of the Use of Hydrochar Pellets in Combined Heat and Power Plants
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2020 (English)In: Sustainability, E-ISSN 2071-1050, Vol. 12, no 21, article id 9026Article in journal (Refereed) Published
Abstract [en]

Hydrothermal carbonization (HTC) has been seen as a potentially beneficial process for converting wet biomass into value-added products. It is, however, necessary to overcome the challenges associated with handling the powdered form of hydrochar—a solid product of the HTC process—by controlling the formation of dust and facilitating smoother transportation and distribution in a potentially wide marketplace. In this paper, the authors investigate the environmental consequences of different alternatives for using hydrochar pellets produced from mixed sludges from pulp and paper mills in Sweden, using the environmental life cycle assessment (E-LCA). Two scenarios for possible end-uses of hydrochar in combined heat and power (CHP) plants as a source of energy (heat and electricity) were assessed. In these scenarios, hydrochar pellets were assumed to be combusted in CHP plants, thereby avoiding the use of combustible solid wastes (Scenario A) and coal (Scenario B), respectively, to recover energy in the form of electricity and heat. The environmental damages to Human Health, Ecosystem Quality, Climate Change, and Resources are evaluated based on 1 tonne of dry sludge as the functional unit. The results from this analysis illustrate that Scenario B, in which hydrochar replaces coal, offers the greatest reduction in all the environmental damage characterizations, except the Resources category. The displacement of energy-based coal due to hydrochar combustion contributed most significantly to the environmental damages wrought by the system—ranging from 52% in Resources to 93% in Ecosystem Quality. Overall, the results highlight that the application of hydrochar pellets for energy recovery to offset waste- and coal-based energy sources has great environmental benefits. The favorability of sludge hydrochar over solid wastes as fuel for CHP plants may be counter-intuitive at first, since HTC is an energy-intensive process, but when accounting for the necessity of dependence on imports of wastes for instance, the hydrochar pellet may well emerge as a good option for CHPs in Sweden.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
mixed sludges; hydrochar pellets; environmental damages; E-LCA; resources
National Category
Energy Systems
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-81192 (URN)10.3390/su12219026 (DOI)000589261800001 ()2-s2.0-85095112271 (Scopus ID)
Projects
Biochar
Available from: 2020-11-03 Created: 2020-11-03 Last updated: 2022-05-30Bibliographically approved
Anukam, A., Mohammadi, A., Naqvi, M. & Granström, K. (2019). A Review of the Chemistry of Anaerobic Digestion: Methods of Accelerating and Optimizing Process Efficiency. Processes, 7(8), 1-19, Article ID 504.
Open this publication in new window or tab >>A Review of the Chemistry of Anaerobic Digestion: Methods of Accelerating and Optimizing Process Efficiency
2019 (English)In: Processes, Vol. 7, no 8, p. 1-19, article id 504Article, review/survey (Refereed) Published
Abstract [en]

The anaerobic digestion technology has been in existence for centuries and its underlying theory established for decades. It is considered a useful technology for the generation of renewable energy, and provides means to alleviate problems associated with low access to energy. However, a great deal of current research is targeted towards the optimization of this technology under diverse digestion process conditions. This review presents an in-depth analysis of the chemistry of anaerobic digestion and discusses how process chemistry can be used to optimize system performance through identification of methods that can accelerate syntrophic interactions of different microorganisms for improved methanogenic reactions. Recent advances in addition to old research are discussed in order to offer a general but comprehensive synopsis of accumulated knowledge in the theory of anaerobic digestion, as well as an overview of previous research and future directions and opportunities of the AD technology. Achieving a sustainable energy system requires comprehensive reforms in not just economic, social and policy aspects, but also in all technical aspects, which represents one of the most crucial future investments for anaerobic digestion systems.

Place, publisher, year, edition, pages
Basel: MDPI, 2019
Keywords
anaerobic digestion, feedstock, syntrophic interaction, process chemistry, methane yield
National Category
Chemical Engineering
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-74884 (URN)10.3390/pr7080504 (DOI)000483747700019 ()
Available from: 2019-09-30 Created: 2019-09-30 Last updated: 2020-01-28Bibliographically approved
Mohammadi, A., Sandberg, M., Govindarajan, V., Eskandari, S., Dalgaard, T. & Granström, K. (2019). Environmental analysis of producing biochar and energyrecovery from pulp and papermill biosludge. Journal of Industrial Ecology, 23(5), 1039-1051
Open this publication in new window or tab >>Environmental analysis of producing biochar and energyrecovery from pulp and papermill biosludge
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2019 (English)In: Journal of Industrial Ecology, ISSN 1088-1980, E-ISSN 1530-9290, Vol. 23, no 5, p. 1039-1051Article in journal (Refereed) Published
Abstract [en]

Sweden is one of the largest exporters of pulp and paper products in the world. It follows that huge quantities of sludge rich in carbonaceous organic material and containing heavy metals are generated. This paper carried out a comparative environmental analysis of three different technologies, which can be adopted to produce biochar and recover energy from the biosludge, using landfilling as the reference case. These three thermochemical biosludge management systems—using incineration, pyrolysis, and hydrothermal carbonization (HTC)—were modeled using life cycle assessment (LCA). Heat generated in the incineration process (System A) was considered to be for captive consumption within the kraft pulp mills. It was assumed that the biochars—pyrochar and hydrochar—produced from pyrolysis (System B) and HTC (System C), respectively, were added to the forest soils. The LCA results show that all the alternative systems considerably improve the environmental performance of biosludge management, relative to landfilling. For all systems, there are net reductions in greenhouse gas emissions (–0.89, –1.43, and –1.13 tonnes CO2‐equivalent per tonne dry matter biosludge in Systems A, B, and C, respectively). System B resulted in the lowest potential eutrophication and terrestrial ecotoxicity impacts, whereas System C had the least acidification potential. The results of this analysis show that, from an environmental point of view, biochar soil amendment as an alternative method for handling pulp and paper mill biosludge is preferable to energy recovery. However, an optimal biochar system needs to factor in the social and economic contexts as well.

Place, publisher, year, edition, pages
Hoboken: John Wiley & Sons, 2019
Keywords
acidification, carbonsequestration, forestry, heavymetals, lifecycleassessment, soilfertility
National Category
Environmental Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-70488 (URN)10.1111/jiec.12838 (DOI)000488924100004 ()
Note

Funding information: 

This study was financially supported by the European Regional Development fund through the Swedish Agency for Economic and Regional Growth, and the NitroPortugal, H2020‐TWINN‐2015, EU coordination and support action no. 692331.

Available from: 2018-12-14 Created: 2018-12-14 Last updated: 2022-05-30Bibliographically approved
Mohammadi, A., Sandberg, M., Govindarajan, V., Eskandari, S., Dalgaard, T., Joseph, S. & Granström, K. (2019). Environmental performance of end-of-life handling alternatives for paper-and-pulp-mill sludge: Using digestate as a source of energy or for biochar production. Energy, 182, 594-605
Open this publication in new window or tab >>Environmental performance of end-of-life handling alternatives for paper-and-pulp-mill sludge: Using digestate as a source of energy or for biochar production
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2019 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 182, p. 594-605Article in journal (Refereed) Published
Abstract [en]

This paper evaluates the environmental impacts of different alternatives for handling of sludge from paper and pulp mills in Sweden, using Life Cycle Assessment (LCA). The common practice of incineration of biosludge with energy recovery followed by landfilling of ash (System A) was compared with the alternative of digesting sludge anaerobically to produce biogas using different digestate residue management options. The digestate produced from anaerobic digestion (AD) was assumed to be incinerated for heat energy recovery in System B or pyrolyzed for biochar production in System C to be mixed with forest soils. The impact categories considered in this work are climate change, non-renewable energy use, mineral extraction, aquatic ecotoxicity, carcinogens and non-carcinogens. The LCA results demonstrate that the two proposed systems significantly reduce the environmental impacts of biosludge management relative to incineration. An 85% reduction in the aquatic ecotoxicity impact is achieved in System C, due to the reduced mobility of heavy metals in biochar relative to ash. System C, on the whole, outperformed the other two, leading the authors to the recommendation that the use of pulp and paper mill biosludge in biogas-biochar production systems is preferable to merely recovering energy from it.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Anaerobic digestion, Ash, Biochar, Forest soils, Heavy metals
National Category
Environmental Sciences
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-73061 (URN)10.1016/j.energy.2019.06.065 (DOI)000479021700048 ()2-s2.0-85067679125 (Scopus ID)
Projects
FOSBE
Funder
Swedish Agency for Economic and Regional Growth, 20201239
Note

Funding text

The authors declare that there are no conflicts of interest. This study was funded by a grant from the Swedish Agency for Economic and Regional Growth , grant number 20201239 , project name Fosbe, and by a European Union grant through the Interreg Sweden-Norway program , grant number 20200023 , project name IMTRIS. Appendix A

Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2022-05-30Bibliographically approved
Eskandari, S., Mohammadi, A., Sandberg, M., Eckstein, R. L., Hedberg, K. & Granström, K. (2019). Hydrochar-Amended Substrates for Production of Containerized Pine Tree Seedlings under Different Fertilization Regimes. Agronomy, 9(7), 1-17
Open this publication in new window or tab >>Hydrochar-Amended Substrates for Production of Containerized Pine Tree Seedlings under Different Fertilization Regimes
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2019 (English)In: Agronomy, E-ISSN 2073-4395, Vol. 9, no 7, p. 1-17Article in journal (Refereed) Published
Abstract [en]

There is a growing body of research that recognizes the potentials of biochar application in agricultural production systems. However, little is known about the effects of biochar, especially hydrochar, on production of containerized seedlings under nursery conditions. This study aimed to test the effects of hydrochar application on growth, quality, nutrient and heavy metal contents, and mycorrhizal association of containerized pine seedlings. The hydrochar used in this study was produced through hydrothermal carbonization of paper mill biosludge at 200 °C. Two forms of hydrochar (powder and pellet) were mixed with peat at ratios of 10% and 20% (v/v) under three levels of applied commercial fertilizer (nil, half and full rates). Application of hydrochar had positive or neutral effects on shoot biomass and stem diameter compared with control seedlings (without hydrochar) under tested fertilizer levels. Analysis of the natural logarithmic response ratios (LnRR) of quality index and nutrient and heavy metal uptake revealed that application of 20% (v/v) hydrochar powder or pellet with 50% fertilizer resulted in same quality pine seedlings with similar heavy metal (Cu, Ni, Pb, Zn and Cr) and nutrient (P, K, Ca and Mg) contents as untreated seedlings supplied with 100% fertilizer. Colonization percentage by ectomycorrhizae significantly increased when either forms of hydrochar were applied at a rate of 20% under unfertilized condition. The results of this study implied that application of proper rates of hydrochar from biosludge with adjusted levels of liquid fertilizer may reduce fertilizer requirements in pine nurseries.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
containerized production systems, heavy metals, paper mill sludge, biochar-ash pellet, quality index
National Category
Environmental Sciences
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-73516 (URN)10.3390/agronomy9070350 (DOI)000478660500044 ()
Projects
FOSBE
Available from: 2019-07-07 Created: 2019-07-07 Last updated: 2019-08-29Bibliographically approved
Mohammadi, A., Govindarajan, V., Sandberg, M., Eskandari, S. & Granström, K. (2019). Life cycle assessment of combination of anaerobic digestion andpyrolysis: focusing on different options for biogas use. Advances in Geosciences, 49, 57-66
Open this publication in new window or tab >>Life cycle assessment of combination of anaerobic digestion andpyrolysis: focusing on different options for biogas use
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2019 (English)In: Advances in Geosciences, ISSN 1680-7340, Vol. 49, p. 57-66Article in journal (Refereed) Published
Abstract [en]

The combination of anaerobic digestion and pyrolysistechnologies could be a novel energy-biochar productionsystem to maximize energy and nutrient recovery frompulp and paper mill sludge. Herein, the life-cycle energy productionand emissions reduction of sludge treatment from atypical pulp and paper mill were investigated, in which alternativeuses of biogas for industrial or household application,in different regions of the world, were assessed. Thethree scenarios considered for different end-uses of biogasare: (A) biogas for vehicle fuel in the transportation sectorin Sweden, (B) biogas for heat and electricity in the powersector in Brazil, and (C) biogas for cooking in households inChina. The results of Environmental Life-Cycle Assessment(E-LCA) show that for all these three scenarios, the use ofbiogas and pyrolysis gas contributes most to emissions mitigation,while the dewatering and drying processes carriedout on the sludge, contribute the most to the environmentalemissions. Addition of biochar to the soil, contributes significantlyto a reduction in global warming by sequesteringcarbon in the soil. Compared to scenarios B and C, ScenarioA, in which biogas substitutes gasoline in transportation, andheat from combusted pyrolysis gases is used for district heatingin Sweden, demonstrates the highest environmental performancefor all the evaluated impact categories.

Place, publisher, year, edition, pages
Copernicus GmbH, 2019
Keywords
Biochar, paper mill sludge, forest soil, LCA
National Category
Earth and Related Environmental Sciences
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-74802 (URN)10.5194/adgeo-49-57-2019 (DOI)
Projects
FOSBE
Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2022-05-30Bibliographically approved
Frodeson, S., Berghel, J., Ståhl, M., Granström, K., Romlin, C. & Thelander, A. (2019). The Potential for a Pellet Plant to Become a Biorefinery. Processes, 7(4), 1-11, Article ID 233.
Open this publication in new window or tab >>The Potential for a Pellet Plant to Become a Biorefinery
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2019 (English)In: Processes, ISSN 2227-9717, Vol. 7, no 4, p. 1-11, article id 233Article in journal (Refereed) Published
Abstract [en]

The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying in a pellet plant. The purpose of the study is to increase the understanding of the effects a mechanical dewatering press has in a pellet production chain and investigate whether a pellet plant could thus become a biorefinery. The evaluations in this study are based on industrial data and initial tests at the university. The results show that the concept of using the mechanical dewatering press together with a packed moving bed dryer reduces energy use by 50%, compared to using only a packed moving bed dryer. The press water could be used as a raw material for biogas, bioplastics, and biohydrogen. Hence, this study points out the possibilities of a pellet plant increasing the efficiency of the drying step, while moving towards becoming a biorefinery.

Place, publisher, year, edition, pages
Basel: MDPI, 2019
Keywords
Energy efficiency, wood pellet production, drying, biorefinery, bioplastics, mechanical dewatering
National Category
Energy Systems
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-72418 (URN)10.3390/pr7040233 (DOI)000467771400056 ()2-s2.0-85067518721 (Scopus ID)
Note

Funding: Swedish Agency for Economic and Regional Growth through the project FOSBE

Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2019-10-14Bibliographically approved
Sandberg, M., Govindarajan, V. & Granström, K. (2018). Experimental study and analysis of the functional and life-cycle global warming effect of low-dose chemical pre-treatment of effluent from pulp and paper mills. Journal of Cleaner Production, 174, 701-709
Open this publication in new window or tab >>Experimental study and analysis of the functional and life-cycle global warming effect of low-dose chemical pre-treatment of effluent from pulp and paper mills
2018 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 174, p. 701-709Article in journal (Refereed) Published
Abstract [en]

Aeration, as a process in pulp and paper wastewater treatment, uses the greatest share of the energy. Therefore, if the energy efficiency of the treatment has to be improved, the focus must be on aeration. A Ivey finding from the trials conducted for this paper, with effluent from a paper and pulp mill, was that the oxygen transfer coefficient could be doubled and the chemical oxygen demand could be decreased by 25%, if the effluent was pre-treated with 30 mg/I of aluminium coagulant (equivalent to 9.4 tonnes per day of AVR to 20000 cubic metres of effluent). Decrease in oxygen requirement implies decreases in aeration energy use. Pulp and paper mill effluents are not as biodegradable as municipal sewage, and the improvement in oxygen transfer properties of the effluent will have a positive influence over a longer period of time in the biological treatment. If the sludge is digested anaerobically, pre-treatment will also result in doubling the potential for methane generation. A holistic analysis of modifications to processes entails a study of the economic and environmental consequences as well. While the economic aspect is beyond the scope of this paper, only the net global warming as an environmental impact category has been studied, by taking recourse to specific emission coefficients. Of the four dosages of ferric aluminium sulphate considered in this analysis, the net greenhouse gas emissions are the least - 426 kg carbon dioxide equivalent per day when the daily consumption is 9.4 tonnes.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Chemical Sciences
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-66538 (URN)10.1016/j.jclepro.2017.10.214 (DOI)000424727100063 ()
Available from: 2018-03-02 Created: 2018-03-02 Last updated: 2022-05-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0380-3533

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