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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: 2019-11-14Bibliographically 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: 2019-08-29Bibliographically 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: 2020-04-14Bibliographically approved
Mohammadi, A., Cowie, A. L., Cacho, O., Kristiansen, P., Mai, T. L. & Joseph, S. (2017). Biochar addition in rice farming systems: Economic and energy benefits. Energy, 140, 415-425
Open this publication in new window or tab >>Biochar addition in rice farming systems: Economic and energy benefits
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2017 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 140, p. 415-425Article in journal (Refereed) Published
Abstract [en]

This study investigated economic returns and energy use of alternative rice production systems in North Vietnam with various residue management options. The traditional practice of open burning of rice residues (System A) was compared with the alternative of converting residues to biochar, which was returned to the paddy fields (System B). It was assumed that households used improved cook-stoves and drum ovens to produce biochar, and that the agronomic impacts of biochar compound with increasing biochar applications until reaching maximum benefit at 18 Mg ha(-1). This amount of biochar would take eight years to be produced in pyrolytic cook-stoves and drum ovens using the rice residues produced on site. The net present value (NPV) of producing rice in the two systems was calculated based on their expected streams of costs and benefits. Biochar addition enhanced the NPV of rice by 12% and reduced the non-renewable energy intensity by 27%, relative to System A, after eight years of application. The difference in NPV values between production systems significantly increased to 23% and 71% by crediting GHG emissions abatement in low and high carbon price scenarios, respectively. These findings demonstrate the potential economic benefits of converting rice residues to biochar for soil application. (C) 2017 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Rice residue, Cost-benefit analysis, Biochar value, Carbon price, Energy input
National Category
Environmental Sciences
Research subject
Environmental Science
Identifiers
urn:nbn:se:kau:diva-75576 (URN)10.1016/j.energy.2017.08.116 (DOI)000415394200039 ()
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2019-11-14Bibliographically approved
Mohammadi, A., Cowie, A. L., Mai, T. L., Brandao, M., de la Rosa, R. A., Kristiansen, P. & Joseph, S. (2017). Climate-change and health effects of using rice husk for biochar-compost: Comparing three pyrolysis systems. Journal of Cleaner Production, 162, 260-272
Open this publication in new window or tab >>Climate-change and health effects of using rice husk for biochar-compost: Comparing three pyrolysis systems
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2017 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 162, p. 260-272Article in journal (Refereed) Published
Abstract [en]

This study presents a comparative analysis of the environmental impacts of different biochar-compost (COMBI) systems in North Vietnam relative to the conventional practice of open burning of rice husks. Three COMBI systems, using different pyrolysis technologies (pyrolytic cook-stove, brick kiln and the BigChar 2200 unit) for conversion of rice husk into biochar were modelled. Biochar was assumed to be composted with manure and straw, and the biochar-compost produced from each system was assumed to be applied to paddy rice fields. Life Cycle Assessment (LCA) showed that the three COMBI systems significantly improved environmental and health impacts of rice husk management in spring and summer compared with open burning, in terms of climate change, particulate matter (PM) and human toxicity (HT) impacts. The differences between the three COMBI systems in the climate change and PM impacts were not significant, possibly due to the large uncertainties. In all systems, the suppression of soil CH4 emissions is the major contributor to the reduced climate effect for the COMBI systems, comprising 56% in spring and 40% in summer. The greatest reduction in the HT impact was offered by the BigChar 2200 system, where biochar is produced in a large-scale plant in which pyrolysis gases are used to generate heat rather than released into the atmosphere. (C) 2017 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2017
Keywords
Pyrolysis gases, Biochar, Compost, Methane emissions, Paddy rice
Identifiers
urn:nbn:se:kau:diva-75581 (URN)10.1016/j.jclepro.2017.06.026 (DOI)000407185500024 ()
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2019-11-12
Mohammadi, A., Cowie, A., Mai, T. L., de la Rosa, R. A., Kristiansen, P., Brandao, M. & Joseph, S. (2016). Biochar use for climate-change mitigation in rice cropping systems. Journal of Cleaner Production, 116, 61-70
Open this publication in new window or tab >>Biochar use for climate-change mitigation in rice cropping systems
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2016 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 116, p. 61-70Article in journal (Refereed) Published
Abstract [en]

This study estimated the climate change effects of alternative rice production systems in North Vietnam with different residue management options, using Life Cycle Assessment (LCA). The traditional practice of open burning of residues (System A) was compared with the alternative of converting residues to biochar, which was returned to the same land area from which the residues were obtained (System B). Pyrolytic cook-stoves and drum ovens were assumed to be used by households to produce biochar, and the cook-stoves produced heat energy for cooking. The annual rate of biochar applied was determined by the amount of biochar produced from the straw and husk available. We assumed that agronomic effects of biochar increased with each annual biochar application until reaching maximum benefits at 18 Mg ha I, which takes eight years to be produced in pyrolytic cook-stoves and drum ovens. The largest contributor to the carbon footprint of rice at the mill gate, was CH4 emissions from soil, in both systems. Biochar addition reduced the carbon footprint of spring rice and summer rice by 26% and 14% respectively, compared with System A, in the first year of application. These values substantially increased to 49% and 38% after eight years of biochar addition. The climate effect of System B was most sensitive to the assumed suppression of soil CH4 emissions due to biochar application. (C) 2015 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2016
Keywords
Life Cycle Assessment, Methane emissions, Rice residues, Pyrolytic cook-stove, Carbon footprint
Identifiers
urn:nbn:se:kau:diva-75577 (URN)10.1016/j.jclepro.2015.12.083 (DOI)000370885800007 ()
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2019-11-12
Mohammadi, A., Cowie, A., Mai, T. L., Anaya de la Rosa, R., Brandao, M., Kristiansen, P. & Joseph, S. (2016). Quantifying the greenhouse gas reduction benefits of utilising straw biochar and enriched biochar. In: M. Ask, V. Bruckman, C. Juhlin, T. Kempka, M. Kuhn (Ed.), EUROPEAN GEOSCIENCES UNION GENERAL ASSEMBLY 2016: . Paper presented at General Assembly of the European-Geosciences-Union, APR 17-22, 2016, Vienna, AUSTRIA (pp. 254-261). Elsevier, 97
Open this publication in new window or tab >>Quantifying the greenhouse gas reduction benefits of utilising straw biochar and enriched biochar
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2016 (English)In: EUROPEAN GEOSCIENCES UNION GENERAL ASSEMBLY 2016 / [ed] M. Ask, V. Bruckman, C. Juhlin, T. Kempka, M. Kuhn, Elsevier, 2016, Vol. 97, p. 254-261Conference paper, Published paper (Refereed)
Abstract [en]

This study investigated the carbon footprint of two different biochar production systems for application to paddy fields. The impacts of using rice straw-derived biochar in raw form (System A) were compared with those arising from using rice straw biochar enriched with lime, clay, ash and manure (System B). The GHG abatement of the management of one Mg of rice straw in Systems A and B was estimated at 0.27 and 0.61 Mg CO2-eq, respectively, in spring season, and 0.30 and 1.22 Mg CO2-eq in summer. The difference is mainly due to greater reduction of soil CH4 emissions by enriched biochar. (C) 2016 The Authors. Published by Elsevier Ltd.

Place, publisher, year, edition, pages
Elsevier, 2016
Series
Energy Procedia, ISSN 1876-6102
Keywords
Life Cycle Assessment, Biomass open burning, Enriched biochar, Methane emissions, Vietnam
National Category
Environmental Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-75578 (URN)10.1016/j.egypro.2016.10.069 (DOI)000390613700035 ()
Conference
General Assembly of the European-Geosciences-Union, APR 17-22, 2016, Vienna, AUSTRIA
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2019-11-21Bibliographically approved
Mohammadi, A., Rafiee, S., Jafari, A., Keyhani, A., Dalgaard, T., Knudsen, M. T., . . . Hermansen, J. E. (2015). Joint Life Cycle Assessment and Data Envelopment Analysis for the benchmarking of environmental impacts in rice paddy production. Journal of Cleaner Production, 106, 521-532
Open this publication in new window or tab >>Joint Life Cycle Assessment and Data Envelopment Analysis for the benchmarking of environmental impacts in rice paddy production
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2015 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 106, p. 521-532Article in journal (Refereed) Published
Abstract [en]

The combined implementation of Life Cycle Assessment (LCA) and Data Envelopment Analysis (DEA) has been identified as a suitable tool for the evaluation of the environmental and economic performance of multiple similar entities. In this study, a total of 82 rice paddy fields for spring and summer growing seasons in north of Iran were assessed using a combined LCA and DEA methodology to estimate the technical efficiency of each farmer. Furthermore, the environmental consequences of operational inefficiencies were quantified and target performance values benchmarked for inefficient units so that ecoefficiency criteria were verified. Results showed average reduction levels of up to 20% and 25% per material input for spring and summer systems, leading to impact reductions which ranged from 8% to 11% for spring farms and 19% to 25% for summer farms depending on the chosen impact category. Additionally, the potential economic savings from efficient farming operations were also determined. The economic results indicate that an added annual gross margin of 0.045 $ per 1 kg rice paddy could be achieved if inefficient units converted to an efficient operation. (C) 2014 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2015
Keywords
Life Cycle Assessment (LCA), Data Envelopment Analysis (DEA), Rice paddy, Growing season, Technical efficiency, Economic savings
Identifiers
urn:nbn:se:kau:diva-75579 (URN)10.1016/j.jclepro.2014.05.008 (DOI)000359955900051 ()
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2019-11-12
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ORCID iD: ORCID iD iconorcid.org/0000-0002-8300-2786

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