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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
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 1530-9290Article in journal (Refereed) Epub ahead of print
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
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)
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: 2019-07-12Bibliographically 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.

Keywords
Biochar, paper mill sludge, forest soil, LCA
National Category
Natural 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: 2019-09-19
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: 2018-06-12Bibliographically approved
From-Aldaron, M., Sandberg, M. & Granström, K. (2018). Low Dosage Chemical Treatment for Improved Oxygenation of Pulp Mill Effluents. Journal of environmental engineering, 144(3), Article ID 06017012.
Open this publication in new window or tab >>Low Dosage Chemical Treatment for Improved Oxygenation of Pulp Mill Effluents
2018 (English)In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 144, no 3, article id 06017012Article in journal (Refereed) Published
Abstract [en]

Most pulp and paper mills use aerobic biological treatment for their effluents. Aeration is the single most energy intensive process of a treatment plant. Surfactants, commonly occurring in pulping wastewaters, have been shown to decrease the oxygen transfer rate. The aim of this study was to decrease the surface activity of surfactants and thereby increase the oxygen transfer rate in pulp mill effluents by the use of chemical pretreatment in very low doses. Trials using 5 g/m(3) ferric iron showed statistically significant improvement on both k(L)a(@20) and surface tension. No sludge was precipitated owing to the very low ferric iron dosage. The novel use of chemical pretreatment, in very low doses, aiming specifically at improving oxygen transfer rate, is a promising concept for reducing the need for aeration in wastewater treatment and thus lower the electricity requirement of the wastewater treatment plant. (c) 2017 American Society of Civil Engineers.

Place, publisher, year, edition, pages
American Society of Civil Engineers (ASCE), 2018
National Category
Energy Systems
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-66051 (URN)10.1061/(ASCE)EE.1943-7870.0001320 (DOI)000422803400005 ()
Available from: 2018-02-01 Created: 2018-02-01 Last updated: 2018-06-25Bibliographically approved
Sandberg, M., Bengtsson, S., Pawar, S., Werker, A., Willquist, K. & Govindarajan, V. (2018). Novel biotechnical cascade concept to upgrade pulp and paper residues to hydrogen gas and polyhydroxyalkanoate (PHA). In: : . Paper presented at ECO-BIO 4-7 May Dublin 2018.
Open this publication in new window or tab >>Novel biotechnical cascade concept to upgrade pulp and paper residues to hydrogen gas and polyhydroxyalkanoate (PHA)
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Pulp and paper mills use approximately 30 m3water per ton of produced paper. The process effluent has to be treated before being discharged. Mostly, the effluent is treated with aerobic biological processes using electricity for aeration, and added nutrients. The bio-sludge has low energy value and has to be disposed of. Here, we propose that effluent instead can be used as a feedstock for valuable products.

 

Some of the bacteria in the bio-sludge can accumulatepolyhydroxyalkanoates(PHAs). PHA is a biopolymer that has a commercial value and is an important building block for the bio-plastics industry. For an efficient PHA production, volatile fatty acids (VFAs) are needed as the feedstock substrate. Process streams rich in sugars can be fermented by the thermophilic bacteria Caldicellulosiruptor, providing acetic acid and hydrogen gas. The acetic acid can then be used as substrate for PHA accumulation. 

 

In a case study conducted at a large integrated pulp and paper mill (>700 000 ADt/y) in Sweden, the theoretical production volume of hydrogen gas and PHA were estimated. The calculations were based on measured process effluent volumes and water quality parameters, biological process yields from laboratory and pilot scale testing, and practical experience for the unit processes. The results indicated that 0.3 kg of hydrogen gas and 1.6 kg of PHA can be produced per ADt paper or board. The additional associated benefits are significant for the mill because the demand for nutrients and energy for aeration may, at the same time, decrease by 15 to 50 percent.

 

By combining common biological treatment with fermentation and PHA accumulation, waste by-products can be transformed and upgraded to value-added hydrogen gas and PHA.  Such a secondary side-process integration helps to shift toward the circular bioeconomy. At the same time, less energy and nutrients are needed for the wastewater treatment.

National Category
Energy Systems
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-70041 (URN)
Conference
ECO-BIO 4-7 May Dublin 2018
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2019-02-07Bibliographically approved
Granström, K. & Sandberg, M. (2017). Characterization of Wood-Dryer Condensate with Assessment of Toxicity to Microorganisms. Journal of environmental engineering, 143(7), Article ID 04017019.
Open this publication in new window or tab >>Characterization of Wood-Dryer Condensate with Assessment of Toxicity to Microorganisms
2017 (English)In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 143, no 7, article id 04017019Article in journal (Refereed) Published
Abstract [en]

Drying of wood causes airborne emissions that can be reduced by recirculating all or part of the drying medium. This favors both emission control and energy efficiency, but results in a condensate that contains significant amounts of organic compounds. Drying operations have been requested by municipal regulatory bodies to clean the condensate before release. The industry has tested biological treatment of condensate from biomass dryers, but maintaining the viability of microorganisms has been a challenge. In this study, the effect of drying gas temperature and the final wood moisture content on the chemical composition and acute toxicity of the condensate was tested. Results showed that whereas the condensate from wood drying was extremely toxic to Vibrio fischeri employed in Microtox assays, the undefined mixed culture present in biosludge from a pulp and paper mill treatment plant were considerably less affected. (C) 2017 American Society of Civil Engineers.

Place, publisher, year, edition, pages
American Society of Civil Engineers (ASCE), 2017
National Category
Energy Systems
Identifiers
urn:nbn:se:kau:diva-65476 (URN)10.1061/(ASCE)EE.1943-7870.0001200 (DOI)000399912100002 ()
Available from: 2017-12-29 Created: 2017-12-29 Last updated: 2018-06-26Bibliographically approved
Sandberg, M. & Granström, K. (2015). Nutrients for microalgae bio-oil production at a pulp and paper mill site, experiences from a pilot plant. In: : . Paper presented at 5th International Conference on Biorefinery - towards Bioenergy University of British Columbia, Aug 10-12.
Open this publication in new window or tab >>Nutrients for microalgae bio-oil production at a pulp and paper mill site, experiences from a pilot plant
2015 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Microalgae are a possible source of bio-oil, for example renewable biodiesel. Micro algae gives higher production capacity per area than any other oil producing crop (Chisti 2007). To become competitive with fossil fuel, the bio-oil production must be efficient and cheap. An algae production pilot plant has been running for two years at the site of Nordic Paper Bäckhammar mill in mid Sweden. The purpose is to develop a competitive production process for bio-oil. The challenge is to achieve an economically competitive process that includes, gaining high production rate even though Sweden is a comparably dark and cold country.

 

The solar radiation is strong enough for algae growth in at least eight months of the year. Radiation inhibition that will be found in other countries closer to the equator can be avoided at this location. However, the low temperature will slow the production rate down during four of these eight months. The possibility to use the excess heat to prolong the growth season is therefore the mayor benefit of growing algae close to a pulp and paper mill. Another benefit is the closeness to the carbon dioxide rich exhaust gas from the recovery boiler. This pilot plant consists of one 25m2 raceway pond and eight smaller pools. The microalgae Scenedesmus Dimorphus is grown in wastewater from the mill. The pools are all covered with a plastic tent to maintain a carbon dioxide rich atmosphere above the surface. However the pulp and paper mill effluent is low in nutrients. The aim with this study is to find efficient and cheap nutrients for algae production, close to the pulp and paper mill site.

 

Tested nutrients were: the pulp and paper mill effluent, bio-sludge from the pulp and paper mill wastewater treatment plant, digester reject from a close by municipal treatment plant and digester reject from algae residue anaerobic digestion. The residues are collected after the bio-oil has been extracted. In order to see if the nutrients are available for the microalgae Scenedesmus dimorphus, have the different nutrients been tested in small-scale 100 ml growth trials. Scenedesmus Dimorphus was also used in the pilot plant. Cost and energy were used to evaluate the different nutrient sources tested. Algae residues from the pilot plant were anaerobically digested in batch tests to produce the algae digester reject. The biogas potential was determined as input for the evaluation. Costs for transportation and decreased cost for energy and chemicals in the municipal wastewater treatment plant were included to evaluate the municipal digester reject.

 

Nutrients from all tested sources, except the one from the bio-sludge, were available for microalgae growth. The concentrations of nutrients were to low in the pulp and paper wastewater to enable growth in one batch. The both rejects contain high concentrations of nutrients. The transportation costs made the municipal reject less suitable. The algae residues will give 250 nml3 methane/gVS. The contribution of energy in form of biogas is almost as large as the energy of the bio-oil. Therefore gave the reject from anaerobically digested algae residues the best results. An efficient system can be algae grown in pulp and paper wastewater complemented with recirculate nutrients from the energy recovery of the residues from the bio-oil production. 

Keywords
bio-oil; microalgae; nutrients; pulp and paper mill.
National Category
Engineering and Technology
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-39213 (URN)
Conference
5th International Conference on Biorefinery - towards Bioenergy University of British Columbia, Aug 10-12
Projects
Algodling hos massa- och pappersbruk för hållbar produktion av bioolja
Funder
VINNOVA
Available from: 2016-02-02 Created: 2016-02-02 Last updated: 2019-07-11Bibliographically approved
Sandberg, M. (2014). The addition of electrostatic precipitator ash to forest industrial wastewater treatments increases the oxygen transfer rate and saves the energy needed for aeration. In: Digital  Proceeding Of The  ICOEST’2014 - , SIDE: . Paper presented at 2nd international conference on environmental science and technology – Side 14–17 may 2014 Side, Antalya Turkey.
Open this publication in new window or tab >>The addition of electrostatic precipitator ash to forest industrial wastewater treatments increases the oxygen transfer rate and saves the energy needed for aeration
2014 (English)In: Digital  Proceeding Of The  ICOEST’2014 - , SIDE, 2014Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

More than 30 m3 of water is needed for each metric tonne of paper. Most of the pulp and paper mills use an aerobic biological wastewater treatment. Aeration is the single most energy demanding process in the wastewater treatment plant; therefore it is desirable to control energy consumption when energy needs to be conserved. The aeration efficiency in pulp and paper industrial effluents is often low.  80 – 90% of added oxygen passes through the water volume and leaves with the off-gases. To increase the aeration efficiency, the process needs the oxygen transfer rate from the air bubble into the water to increase. The bubble size affects the oxygen transfer rate. In small bubbles, with a larger area/volume ratio the oxygen transfer rate is often fast and more efficient. The wastewater properties affect the bubble size. A decreased surface tension ensures smaller bubbles. The aim of this study was to show that a waste material, precipitator ash, could be used to decrease wastewater surface tension and thereby increase the oxygen transfer rate. The results from laboratory aeration trials show that the oxygen transfer rate coefficient (KLa) increases by 25% when small concentrations of electrostatic precipitator ash, from a flue gas treatment, were added to the process effluent.

Keywords
Oxygen transfer rate, Precipitator ash, Pulp and Paper, Surface tension, Wastewater
National Category
Engineering and Technology
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-33757 (URN)
Conference
2nd international conference on environmental science and technology – Side 14–17 may 2014 Side, Antalya Turkey
Projects
Salta bubblor
Available from: 2014-09-19 Created: 2014-09-19 Last updated: 2015-07-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1065-1221

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