https://www.mdu.se/

mdu.sePublications
Change search
Refine search result
1234 101 - 150 of 185
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 101.
    Odlare, Monica
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering.
    Ribé, Veronica
    Mälardalen University, School of Business, Society and Engineering.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Grube, Mara
    University of Latvia.
    Gavare, Marita
    University of Latvia.
    Cultivation of algae with indigenous species: potentials for regional biofuel production2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 10, p. 3280-3285Article in journal (Refereed)
    Abstract [en]

    The massive need for sustainable energy has led to an increased interest in new energy resources, such as production of algae, for use as biofuel. There are advantages to using algae, for example, land use is much less than in terrestrial biofuel production, and several algae species can double their mass in one day under optimized conditions. Most algae are phototrophs and some are nitrogen fixing. Algae production therefore requires only small amounts of amendments such as carbon sources and nutrients. In the present paper an experiment was performed using water sampled from Lake Mälaren in Sweden. The lake water is considered nutrient rich, has relatively neutral pH and is rich in organic compounds and suspended solids. The idea behind this research was to enhance indigenous algae production rather than inoculate new species into the system. A simple experimental setup was designed where algae biomass growth was measured regularly over a 13 day period. FT-IR absorption spectra were evaluated in order to determine protein, lipid, carbohydrate and silicate contents of the algae. The algae community structure was characterized throughout the production cycle. Futhermore, the potential for energy supply for the transportation sector in the Mälardalen region from algae cultivated as tested in the experiment was evaluated.

  • 102.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Feng, Xin Mei
    JTI, Swedish Inst Agr & Environm Engn, SE-75007 Uppsala, Sweden .
    Ascue, Johnny
    JTI, Swedish Inst Agr & Environm Engn, SE-75007 Uppsala, Sweden .
    Gentili, Francesco G.
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Studies, SE-90183 Umea, Sweden .
    Shabiimam, M. A.
    Indian Inst Technol, Ctr Environm Sci & Engn, Bombay 400076, Maharashtra, India.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatment2014In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 171, p. 203-210Article in journal (Refereed)
    Abstract [en]

    In this study two wet microalgae cultures and one dried microalgae culture were co-digested in different proportions with sewage sludge in mesophilic and thermophilic conditions. The aim was to evaluate if the co-digestion could lead to an increased efficiency of methane production compared to digestion of sewage sludge alone. The results showed that co-digestion with both wet and dried microalgae, in certain proportions, increased the biochemical methane potential (BMP) compared with digestion of sewage sludge alone in mesophilic conditions. The BMP was significantly higher than the calculated BMP in many of the mixtures. This synergetic effect was statistically significant in a mixture containing 63% (w/w VS based) undigested sewage sludge and 37% (w/w VS based) wet algae slurry, which produced 23% more methane than observed with undigested sewage sludge alone. The trend was that thermophilic co-digestion of microalgae and undigested sewage sludge did not give the same synergy.

  • 103.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Forkman, T.
    Swedish University of Agricultural Sciences, Sweden.
    Gentili, F.G.
    Swedish University of Agricultural Sciences, Sweden.
    Zambrano, Jesús
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Anaerobic co-digestion of sludge and microalgae grown inmunicipal wastewater: A feasibility study2018In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 77, no 3, p. 682-694Article in journal (Refereed)
    Abstract [en]

    In this study a natural mix of microalgae grown in wastewater of municipal character was co-digested with sewage sludge in mesophilic conditions, in both batch and semi-continuous modes. The semicontinuous experiment was divided into two periods with OLR 1 (Organic Loading Rate) of 2.4 kg VS m3 d-1 and HRT1 (Hydraulic Retention Time) of 15 days, and OLR2 of 3.5 kg VS m3 d-1 and HRT2 of 10 days respectively. Results showed stable conditions during both periods. The methane yield was reduced when adding microalgae (from 200 ± 25 NmL CH4 g VSin-1 , to 168±22 NmL CH4 g VSin-1). VS reduction was also decreased by 51%. This low digestability was confirmed in the anaerobic batch test. However, adding microalgae improved the dewaterability of the digested sludge. The high heavy metals content in the microalgae resulted in a high heavy metals content in the digestate, making it more difficult to reuse the digestate as fertilizer on arable land. The heavy metals are thought to originate from the flue gas used as a CO2 source during the microalgae cultivation. Therefore the implementation of CO2 mitigation via algal cultivation requires careful consideration regarding thesource of the CO2-rich gas.

  • 104.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Ma, Shabiimam
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nehrenheim, Emma
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatmentManuscript (preprint) (Other academic)
    Abstract [en]

    One way to meet the increased demand for biogas in the society is to use microalgae as substrate. These algae would be cultivated in a treatment step of photobioreactors for reject water from sludge dewatering facilities. In the present study, a co-digestion experiment was established where sludge from a municipal wastewater treatment plant was fermented with harvested microalgae cultivated in lake water from lake Mälaren. The experiment was carried out as a BMP-test (Biochemical Methane Potential) under mesophilic condition (37°C) with fermentation bottles, where 0, 12, 25 and 37%, of the sludge was replaced with harvested microalgae. The results showed that the biogas production was improved with 12% for the bottles with 12% microalgae compared with the bottles with only sludge as a substrate. In the bottles with 25% and 37% microalgaes the gas production was slightly reduced compared with the bottles where only sludge was used.

    Download full text (pdf)
    Co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatment
  • 105.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Philipson, M.
    Uppsala University, Sweden.
    Holmström, H.
    Uppsala Vatten Och Avfall AB, Sweden.
    Cato, E.
    Uppsala Vatten och Avfall AB, Sweden.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Energy efficient combination of sewage sludge treatment and hygenization after mesophilic digestion - Pilot study2014In: Energy Procedia, ISSN 1876-6102, Vol. 61, p. 587-590Article in journal (Refereed)
    Abstract [en]

    Biogas production is probably the most feasible way of utilizing sewage sludge as energy source, simultaneously with nutrient recovery by recycling the biogas digestate (i.e. The residue) to arable land. However, the sludge commonly contains high amounts of human pathogenic bacteria excreted in faeces and urine. To use sludge as fertilizer on food producing land is therefore a controversial issue, partly because of the risk of spreading diseasecausing pathogens. The Swedish environment protection agency (SEPA) pre-approved two hygenization methods for the treatment of the sludge due to their positive effects on the sludge quality. One of them, conventional pasteurization (70 °C, 1 h), was investigated for its feasibility in Uppsala, Sweden, and it was found that the heat consumption was very high. The other method has the advantage of potentially increase the produced biogas. This hygenization method has been investigated in the present study through a pilot experiment where thickened mesophilic digested sludge is digested once more at thermophilic conditions (55 °C). The aim of the study was to investigate the possibility to develop this self-sufficient (in heat and electricity) hygenization method. The results showed an increase in the gas production from 430 dm3/kg VSin to 610 dm3/kg VSin by adding the thermophilic step. This increase gave an energy balance with an excess of both heat and electricity. Sludge hygenization was sufficient with the method and another important result is the significant decrease digestate volume.

  • 106.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Co-digestion of microalgae, grown on municipal wastewater, and primary sewage sludge–: Pilot study in thermophilic and mesophilic conditions2017Conference paper (Refereed)
    Abstract [en]

    The most common biological treatment in a municipal waste water today is the activated sludge process (ASP). A possible substitution of the ASP could be the utilization of microalgae for the reduction and/or transformation of nutrients. The produced algal biomass can be converted to biofuel by anaerobic digestion. In the present study, co-digestion of primary sludge and microalgae are studied in semi-continuous tests at mesophilic and thermophilic conditions. Two reactors fed by waste activated sludge and primary sludge are used as reference. The results show that thermophilic digestion of microalgae and primary sludge is less attractive since the methane yield is approximately the same as the mesophilic digestion. In mesophilic conditions the results are approximately the same in the two pilot reactors and also comparable with the mesophilic full-scale digesters in Västerås, Sweden.

  • 107.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Mesophilic and thermophilic co-digestion of microalgal-based activated sludge and primary sludgeManuscript (preprint) (Other academic)
  • 108.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Microalgae as biological treatment for municipal wastewater - Effects on the sludge handling in a treatment plant2018In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, ISSN 0273-1223, Vol. 78, no 3, p. 644-654Article in journal (Refereed)
    Abstract [en]

    A mix of microalgae and bacteria was cultivated on pre-sedimented municipal wastewater in a continuous operated microalgae-activated sludge process. The excess material from the process was co-digested with primary sludge in mesophilic and thermophilic conditions in semi-continuous mode (5 L digesters). Two reference digesters (5 L digesters) fed with waste-activated sludge (WAS) and primary sludge were operated in parallel. The methane yield was slightly reduced (≈10%) when the microalgal-bacterial substrate was used in place of the WAS in thermophilic conditions, but remained approximately similar in mesophilic conditions. The uptake of heavy metals was higher with the microalgal-bacterial substrate in comparison to the WAS, which resulted in higher levels of heavy metals in the digestates. The addition of microalgal-bacterial substrate enhanced the dewaterability in thermophilic conditions. Finally, excess heat can be recovered in both mesophilic and thermophilic conditions. 

  • 109.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Shabiimam, MA
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nehrenheim, Emma
    Mälardalen University, School of Sustainable Development of Society and Technology. Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    CO-DIGESTION OF CULTIVATED MICROALGAE AND SEWAGE SLUDGE FROM MUNICIPAL WASTE WATER TREATMENT2013Conference paper (Refereed)
    Abstract [en]

    The demand for biogas is continuously growing and the biogas substrate, such as food waste, may soon become limited and it is therefore important for biogas producers to expand the range of substrates. One way can be to use microalgae in co-digestion with sewage sludge.

    The present study explores the possibilities to use harvested microalgae from Lake Mälaren, as a co-substrate to sewage sludge in biogas production under mesophilic and thermophilic conditions. The aim is to investigate if co- digestion of microalgae and sewage sludge is more efficient for biogas production compared using the sludge alone. The study has been carried out as a BMP-experiment (Biochemical Methane Potential) in batch fermentation bottles. The substrate was undigested sludge where 0%, 12 %, 25 % and 37 % were replaced with the cultivated microalgae. The results showed that the use of an algae/bacteria community, cultivated in prior to digestion, can serve as a biomass substrate for biogas production together with municipal wastewater sludge. Co-digestion of microalgae and sewage sludge can be more efficient for biogas production compared to using the sludge alone under mesophilic conditions. It can also be concluded that thermophilic co-digestion between the microalgae and sludge give lower biochemical methane potential. 

    Download full text (pdf)
    fulltext
  • 110.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    TRANSITION OF MESOPHILIC TO THERMOPHILIC DIGESTION OF SEWAGE SLUDGE2016In: TRANSITION OF MESOPHILIC TO THERMOPHILIC DIGESTION OF SEWAGE SLUDGE, 2016Conference paper (Refereed)
    Abstract [en]

    In this comparative study two types of temperature transition strategies from mesophilic to thermophilic conditions in anaerobic digestion was explored. Both strategies used a rapid increase from 37 to 55°C with a constant organic loading rate (2.4 kg VS m-3 d-1) and hydraulic retention time (14 d). The two digesters used the same mesophilic inoculoum but in the second digester a small share of thermophilic digeastate was also inoculated. A comparative dewaterability study between the fullscale mesophilic digestate and the thermophilic digestates were also performed as part of the study. The results showed a stabilization in both digesters within 14 days (1 Hydraulic retention time). The digester where a small share of thermophilic inoculum was introduced had a higher methane production compared to the control reactor where just mesophilic inoculum was used. The comparative dewaterability study showed a deterioration of the dewaterability in both digesters when thermophilic conditions was established.

  • 111.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Juszkiewicz, Agnieszka
    Mälarenergi AB, Sweden.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    COMPARATIVE STUDY – PHARMACEUTICAL RESIDUES IN WASTEWATER AND SLUDGE FROM A MICORALGAE PLANT AND AN ACTIVATED SLUDGE PROCESS2016Conference paper (Refereed)
    Abstract [en]

    This study explores the possibility of using a microalgae based activated sludge – process (MAAS-process) to increase the reduction of pharmaceutical residues in outgoing wastewater, compared to a conventional wastewater treatment plant with activated sludge process. In an on-site study, residual sludge from four pilot scale digesters fed with primary sludge and waste activated sludge or microalgae were sampled and analysed for pharmaceutical residues. The aim of the study was to compare the reduction efficiencies of a microalgae based process with a conventional biological treatment and also to explore the reduction of the residues in the different process steps including the sewage sludge thickening before the anaerobic digestion, the digestion and the secondary treatment with the sludge dewatering process. The results show that the total reduction of pharmaceutical residues in the water phase appears to be significantly higher in the MAAS-process. The substance diclofenac was not degraded in any of the biological processes in the study. The reduction of pharmaceutical residues in digested sludge seems to be higher in mesophilic conditions compared with thermophilic conditions.

  • 112.
    Olsson, Jesper
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Tova, Forkman
    Uppsala Universitet, Sweden.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    CONTINUOUS CO-DIGESTION OF MICROALGAE AND REPRESENTATIVE MIX OF SEWAGE SLUDGE: -2014Conference paper (Refereed)
    Abstract [en]

    A natural mix of microalgae grown on wastewater was co-digested with a representative mix of sewage sludge in a semicontinuous pilot digester system. The share of microalgae in the mix were 37 % calculated as VS-content. The organic loading rate was 2.4 kg VS (volatile solids) m-3d-1 and the hydraulic retention time was 15 d in a reference reactor, with just a representative mix of sewage sludge, and a digester where microalgae were added. The results from the three retention times showed that the addition of the microalgae enhanced the methane yield with 39 % for every gram reduced VS in the reactors. The specific methane yield for every gram added VS to the reactors were 9 % lower in the digester where microalgae had been added. Less sludge was degraded when microalgae were added, but more methane was produced for every gram VS reduced. CST-measurements indicated that the addition of microalgae enhance the dewaterability of the digested sludge.

  • 113.
    Paz, Ana
    et al.
    Mälardalen University, Department of Public Technology.
    Nyström, Jenny
    Thorin, Eva
    2006 IEEE Instrumentation and Measurement Technology Conference Proceedings2006In: IEEE Instrumentation and Measurement Technology Conference Proceedings, 2006, p. 175-179Conference paper (Refereed)
    Abstract [en]

    A method that permits the determination of moisture content in biofuel in a fast and representative way is under development. Vie method uses radio frequency waves within the range of 310 MHz to 800 MHz and measures the reflection coefficient in samples with volume of about 0.1 m(3). The influence of sample temperature in the measurements is shown in this study. Two biofuel types were used, with moisture content varying between 31% and 63% and temperature varying between 1 degrees C and 63 degrees C. The data was evaluated with multivariate data analysis. Results show that it is not possible to identify the sample temperature as a principal component in a principal component analysis and partial least squares regression shows no correlation between temperature and the radio frequency data. For the frequency interval and the temperature range studied, it was not possible to detect any influence of sample temperature on moisture content prediction with the radio frequency method.

  • 114.
    Paz, Ana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Starfelt, Fredrik
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    How to achieve a fossil fuel free Malardalen region2007In: Conference proceedings of 3rd IGEC-2007,, 2007Conference paper (Refereed)
  • 115.
    Paz, Ana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    A new method for bulk measurement of water content in woody biomass2008In: 3rd Conference on environmental compatible forest products, 2008Conference paper (Refereed)
  • 116.
    Paz, Ana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nyström, Jenny
    Eskilstuna Energi och Miljö.
    Complex Permittivity of Woody Biomass at Radio FrequenciesManuscript (preprint) (Other (popular science, discussion, etc.))
  • 117.
    Paz, Ana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nyström, Jenny
    Eskilstuna Energi och Miljö.
    Dielectric Properties of Woody Biomass at Radio Frequencies2009In: Proceedings of the 8th International Conference on. Electromagnenetic Wave Interaction with Water and Moist Substances, Helsinki, 2009Conference paper (Refereed)
    Abstract [en]

    Electromagnetic sensing has been found an interesting technique for the characterization of woody biomass. The knowledge of the dielectric properties is useful for this characterization and to improve the understanding of the dielectric behavior of the material. This study presents the dielectric properties of woody biomass at a center frequency of 555 MHz. A measurement system, previously developed, to determine the water content of biomass was used. This system uses a reflection method and measures a biomass volume of about 0.11 m3. The dielectric properties were extracted from attenuation and velocity of the electromagnetic waves in three types of woody biomass with varying water content.

  • 118.
    Paz, Ana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Topp, Clarke
    Agriculture and Agri-food Canada.
    Dielectric mixing models for water content determination in woody biomass2011In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 45, no 2, p. 249-259Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to determine the dielectric constant of woody biomass at different water contents and describe its behavior with a dielectric mixing model. The use of the model for determination of water content is also verified. Dielectric constants were calculated from the travel times of electromagnetic waves with a center frequency of 555 MHz through collected biomass samples. The power law, Maxwell-Garnett, and Polder van Santen mixing models were applied to the experimental data. In the models, biomass was considered as a mixture of three phases: a solid solution composed of wood cellular material and bound water, free water, and air. The experimental data was found to be better described by the Maxwell-Garnett model. The use of this model along with an independent validation set for the determination of volumetric water content resulted in a root mean square error of prediction of 0.03 within the investigated volumetric water content range of 0.07-0.29.

  • 119. Paz, Ana
    et al.
    Trabelsi, Samir
    Nelson, Stuart
    Thorin, Eva
    Influence of sodium chloride on sawdust dielectric propertiesIn: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662Article in journal (Refereed)
  • 120.
    Paz, Ana
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Trabelsi, Samir
    ARS, USDA, Richard B Russell Agr Res Ctr, Athens, GA 30605 USA.
    Nelson, Stuart
    ARS, USDA, Richard B Russell Agr Res Ctr, Athens, GA 30605 USA.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Measurement of the Dielectric Properties of Sawdust Between 0.5 and 15 GHz2011In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 60, no 10, p. 3384-3390Article in journal (Refereed)
    Abstract [en]

    The aim of this paper was to measure the broadband dielectric properties of sawdust. Knowledge of dielectric properties is important in improving understanding of a material and can lead to the development of methods for determining physical properties such as moisture and salt content. The broadband dielectric properties of sawdust were measured with an open-ended coaxial-line dielectric probe. Measurements on granular materials with the dielectric probe are dependent on the density of the measured region, which may differ from the average density of the sample. In this paper, a method was developed for determining the actual density for measurements with the dielectric probe. It consists of measurement of the dielectric constant with a different method (in this instance, a free-space transmission method) at a frequency common to both methods and identifying a relationship between the measured dielectric constant and density. The dielectric properties of sawdust samples with moisture content levels between 13% and 45% are presented for frequencies between 0.5 and 15 GHz.

  • 121.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Future directions for CHP plants using biomass and waste - Adding production of vehicle fuels2019In: E3S Web of Conferences, EDP Sciences , 2019, article id 01006Conference paper (Refereed)
    Abstract [en]

    In Northern Europe, the production of many biobased CHP plants is getting affected due to the enormous expansion of wind and solar power. In addition, heat demand varies throughout the year, and existing CHP plants show less technical performance and suffer economically. By integrating the existing CHP plants with other processes for the production of chemicals, they can be operated more hours, provide operational and production flexibility and thus increase efficiency and profitability. In this paper, we look at a possible solution by converting an existing CHP plant into integrated biorefinery by retrofitting pyrolysis and gasification process. Pyrolysis is retrofitted in an existed CHP plant. Bio-oil obtained from pyrolysis is upgraded to vehicle grade biofuels. Gasification process located upfront of CHP plant provides the hydrogen required for upgradation of biofuel. The results show that a pyrolysis plant with 18 ton/h feed handling capacity (90 MWth), when integrated with gasification for hydrogen requirement and CHP plant for heat can produce 5.2 ton/h of gasoline/diesel grade biofuels. The system integration gives positive economic benefits too but the annual operating hours can impact economic performance. 

  • 122.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Naqvi, Muhammad
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Royal Institute of Technology, Stockholm, Sweden.
    A polygeneration process for heat, power and DME production by integrating gasification with CHP plant: Modelling and simulation study2017In: Energy Procedia, ISSN 1876-6102, Vol. 142, p. 1749-1758Article in journal (Refereed)
    Abstract [en]

    Biofuels are a good substitute for the transport sector petroleum fuels to minimize carbon footprint and greenhouse gases emissions. Di-Methyl Ether (DME) is one such alternative with properties similar to liquefied petroleum gas but with lower SOx, NOx, and particulate emissions. In this work, a polygeneration process, integrating an existing combined heat and power (CHP) plant with biomass gasification to synthesize DME, is proposed and modelled. Process integration is based on a hypothesis that the CHP plant provides the necessary heat to run the co-located gasification plant for DME synthesis and the waste heat from the gasification process is recovered and transferred to the CHP plant. The feed for gasification is taken as refuse derived fuel (RDF) instead of conventional wood derived biomass. The process integration leads to higher overall combined efficiency (up to 71%) which is greater than stand-alone efficiencies (up to 63%) but lower than stand-alone CHP plant efficiency (73.2%). The further technical evaluation shows that the efficiency of the polygeneration process is depends heavily on the gasifier capacity integrated with the existing CHP plant and also on the conversion route selected for DME synthesis i.e. recycling of unconverted syngas to the DME reactor or transferring it to the boiler of the CHP plant. The simulation results also indicate that once-through conversion yields less DME than recycling, but at the same time, once-through conversion affects the district heat and electric power production of the CHP plant lesser than by using the recycling route.

    Download full text (pdf)
    fulltext
  • 123.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Naqvi, Muhammad
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Karlstad University, Sweden.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Royal Institute of Technology, Stockholm, Sweden.
    Gasification process integration with existing combined heat and power plants for polygeneration of dimethyl ether or methanol: A detailed profitability analysis2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 226, p. 116-128Article in journal (Refereed)
    Abstract [en]

    Combustion of waste for cogeneration of heat and power is the most convenient and practical choice to carry out through combined heat and power (CHP) plants. But, seasonal variation in heat demand throughout the year affects the operation of CHP plants. This fluctuation in the CHP operation cause less annual operating hours for the plant equipment and is also not profitable for stakeholders. This study aims to assess the technical potential of integrated gasification process with existing CHP plants for either dimethyl ether (DME) or methanol production through refuse-derived fuel (RDF). Process integration considers that the CHP plant provides the necessary heat for biofuel synthesis during off-peak hours. Mass and heat integration methods are used to develop and simulate the polygeneration processes for heat, power, and biofuel production. Both technical and economic indicators are reported and compared to assess the potential for both biofuels through process integration. Annual operation data of a real CHP plant has been extracted to evaluate the integrated processes. A flexible gasification configuration is selected for the integrated approach i.e. CHP runs at full load to provide the heat demand and only the excess heat of CHP plant is utilized for biofuel production. The energetic efficiencies of the polygeneration systems are compared with the standalone systems. Technical analysis of process integration shows the enhancement of the operational capacity of CHP during off-peak hours and it can produce biofuels without compromising the annual heat demand. Production of methanol through process integration shows ∼67% energetic efficiency while methanol production gives ∼65%. The efficiencies are higher than standalone DME and methanol processes (51% and 53%, respectively) but lower than standalone CHP plant i.e. 81%, however the process integration increases the operating time of the CHP plant with more economic benefits. Economic analysis coupled with uncertainty analysis through Monte Carlo simulations shows that by integrating CHP with gasifier to produce biofuels is significantly profitable as compared with only heat and electricity production. But, DME as a potential product shows more economic benefits than methanol. The uncertainty analysis through Monte Carlo simulations shows that the profitable probability of DME as a product in future is also greater than methanol due to higher DME selling price. The uncertainty analysis further shows that prices of DME and methanol with waste biomass prices in future will have a greater impact on the economic performance of the proposed polygeneration process. 

  • 124.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Naqvi, Muhammad
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Impact of retrofitting existing combined heat and power plant with polygeneration of biomethane: A comparative techno-economic analysis of integrating different gasifiers2017In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 152, p. 250-265Article in journal (Refereed)
    Abstract [en]

    It is vital to identify and evaluate the optimal gasifier configuration that could be integrated with existing or new combined heat and power (CHP) plants to maximize the utilization of boiler operating capacity during off-peak hours with minimal effect on the boiler performance. This study aims to identify technically and economically most suitable gasification configuration and the reasonable operational limits of a CHP plant when integrated with different types of gasifiers. The selected gasifiers for the study are, (i) indirectly heated dual fluidized bed gasifier (DFBG), (ii) directly heated circulating fluidized bed gasifier (CFBG), and (iii) entrained flow gasifier (EFG). The gasifiers are selected on their ability to produce high-quality syngas from waste refused derived fuel (RDF). The syngas from the gasifiers is utilized to produce biomethane, whereas the heat and power from the CHP plant are consumed to run the gasification process. A detailed techno-economic analysis is performed using both flexible capacity and fixed capacity gasifiers and integrated with the CHP plant at full load. The results reveal that the integration leads to increase in operating time of the boiler for all gasifier configurations. The indirectly heated DFBG shows the largest biomethane production with less impact on the district heat and power production. Extra heat is available for biomethane production when the district heat and biomethane are prioritized, and the electric power is considered as a secondary product. Furthermore, the economic indicators reflect considerable dependency of integrated gasification performance on variable prices of waste biomass and biomethane. 

  • 125.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Naqvi, M.
    Karlstad University, Sweden.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH.
    Synergistic combination of pyrolysis, anaerobic digestion, and CHP plants.2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 1323-1329Conference paper (Refereed)
    Abstract [en]

    The anaerobic digestion of biodegradable fraction of municipal solid waste (MSW) is a widely used process for biogas production. However, the biodegradable fraction of MSW also contains lignocellulosic waste which hinders the biogas production if added to the digester in higher quantity. So it needs to be separated from biodegradable waste and sent for alternate treatment, e.g., incineration, landfilling or compositing. Pyrolysis of lignocellulosic waste to produce biochar, syngas, and bio oil is an alternate treatment to consider. Furthermore, there is a reported correlation between the addition of biochar in the digester and higher biogas production. Previously, we coupled the pyrolysis of lignocellulosic waste with anaerobic digestion plant. Pyrolysis produces the biochar and vapors. Biochar was added in the digester to enhance the biomethane production. The vapors produced in the pyrolysis process were converted to biomethane through the catalytic methanation process. The combination gives the overall efficiency of 67%. In this work, we modified the process concept to increase the integration level of these processes. The main issue with the pyrolysis process is its heat required to operate, while some of its downstream processes also generate excess heat. In this study, the pyrolysis of lignocellulosic waste is integrated with an operating combined heat and power (CHP) plant, by using its existing infrastructure for heat transport among different pyrolysis operations. The combustor of the CHP plant provides the heat for drying and pyrolysis while the excess heat is transferred back to the combustor. The biochar produced from pyrolysis is transported back to the digester as an adsorbent. The process simulation results show that the combined efficiency of pyrolysis with CHP plant reached 80%. If the biochar is sent back to the anaerobic digester, the synergetic efficiency of all three processes, i.e., pyrolysis-CHP and anaerobic digestion was obtained at 79.7% as compared with the 67% efficiency when the pyrolysis was only integrated with the anaerobic digestion process.

  • 126.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH.
    Identification of thermochemical pathways for the energy and nutrient recovery from digested sludge in wastewater treatment plants2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 1317-1322Conference paper (Refereed)
    Abstract [en]

    There are several restrictions and limitations on the emissions and disposal of materials and pollutants related to wastewater treatment plants (WWTPs) emphasizing improvement of current processes and development of new methods. Process integration is one way to use all fractions of waste for improved efficiency. WWTPs produces sludge which is usually anaerobically digested to produce biogas and a byproduct called digestate. Digestate is an organic material that contains macro and micronutrients such as nitrogen, phosphorous, and potassium and also contains heavy metals. Digestate is mainly used for agricultural applications because of the presence of nutrients. However, digestate also contains energy in the form of carbon and hydrogen which can be harnessed through various processes and integrated with nitrogen recovery process. This study aims to recover the energy and nutrients from digestate through thermochemical treatment processes. Combustion, pyrolysis, and gasification are assessed and compared in this work. An ammonia stripping method is assumed to recover nitrogen from digestate. The thermochemical processes are heat integrated with ammonia stripping through modeling and simulation. Results show that almost half of the energy present in digested sludge is required for its drying. Moreover, nitrogen recovery also requires much energy. The combustion and gasification of digested sludge give better results than pyrolysis. The heat integration becomes feasible when the auxiliary biogas is also burned along with products from the thermochemical treatment of sludge.

  • 127.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Enhancing biomethane production by integrating pyrolysis and anaerobic digestion processes2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 204, p. 1074-1083Article in journal (Refereed)
    Abstract [en]

    The anaerobic digestion of source-separated organic waste is a mature and increasingly used process for biomethane production. However, the efficient use of different fractions of waste is a big concern in anaerobic digestion plants. This study proposes the use of a new process configuration that couples the anaerobic digestion of biodegradable waste with the pyrolysis of lignocellulosic or green waste. The biochar obtained from pyrolysis was added to a digester as an adsorbent to increase the biomethane content and to support the development of a stable microbial community. In addition, the bio-oil and syngas produced by the pyrolysis process were reformed into syngas and then converted to biomethane via methanation. Modelling and simulations were performed for the proposed novel process. The results showed an approximately 1.2-fold increase in the biomethane volume produced. An overall efficiency of 67% was achieved, whereas the stand-alone anaerobic digestion system had an efficiency of only 52%. The results also indicated a high annual revenue for the integrated process compared to that for an alternative treatment (incineration) of green waste.

  • 128.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Royal Institute of Technology, Stockholm, Sweden.
    Predictive modelling and simulation of integrated pyrolysis and anaerobic digestion process2017In: Energy Procedia, ISSN 1876-6102, Vol. 105, p. 850-857Article in journal (Refereed)
    Abstract [en]

    Anaerobic co-digestion plant with biodegradable organic feedstock separated from municipal solid waste (MSW) have become a mature technology in past decade. The biogas produced can be upgraded to bio-methane or used in heat and power applications. However, not all the municipal waste fractions such as ligno-cellulose and green waste, are suitable for biodegradation. In this work, the non-biodegradable organic waste named as green waste is investigatedas a potential substrate for a bio refinery conceptbased on combination of pyrolysis and anaerobic digestion.

    The main aim of the study was to evaluate whether or not the anaerobic digestion and pyrolysis process coupling could be beneficial from an energy and exergy point of view. The simulation results shows that the integration of pyrolysis process gives approximately 59% overall efficiency as compared to the 52% for a naerobic digestion stand-alone process. The results also revealed that the pyrolysis of green waste is more beneficial than green waste incineration for heat and power production.

  • 129.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Process simulation and comparison of biological conversion of syngas and hydrogen in biogas plants2017In: E3S Web of Conferences, EDP Sciences , 2017, article id 00151Conference paper (Refereed)
    Abstract [en]

    Organic waste is a good source of clean energy. However, different fractions of waste have to be utilized efficiently. One way is to find pathways to convert waste into useful products via various available processes (gasification, pyrolysis anaerobic digestion, etc.) and integrate them to increase the combined efficiency of the process. The syngas and hydrogen produced from the thermal conversion of biomass can be upgraded to biomethane via biological methanation. The current study presents the simulation model to predict the amount of biomethane produced by injecting the hydrogen and syngas. Hydrogen injection is modelled both in-situ and ex-situ while for syngas solely the ex-situ case has been studied. The results showed that 85% of the hydrogen conversion was achieved for the ex-situ reactor while 81% conversion rate was achieved for the in-situ reactor. The syngas could be converted completely in the bio-reactor. However, the addition of syngas resulted in an increase of carbon dioxide. Simulation of biomethanation of gas addition showed a biomethane concentration of 87% while for hydrogen addition an increase of 74% and 80% for in-situ and ex-situ addition respectively.

    Download full text (pdf)
    fulltext
  • 130.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Opportunities and limitations for existing CHP plants to integrate polygeneration of drop-in biofuels with onsite hydrogen production2020In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 221, article id 113109Article in journal (Refereed)
    Abstract [en]

    Over the past few years, there has been increasing research interest in retrofitting existing combined heat and power (CHP) plants with new technologies to co-produce other products. The focus has been on the design of fixed-sized processes for integration into CHP plants without affecting their performance. The primary objective of this study was to test the limits of a CHP plant with respect to retrofitting flexible thermochemical conversion of waste to drop-in biofuels with properties similar to petroleum fuels. Waste conversion to drop-in biofuels also requires significant amount of hydrogen for drop-in biofuels synthesis — Required hydrogen was also produced onsite in thermochemical processes integrated with CHP plant. The secondary objective was to determine the maximum number of days a flexible retrofitted waste-thermochemical process can run annually using only excess heat from a CHP plant, and whether such processes are profitable when operating flexibly. The results show that the selection of heat extraction points for the utilization of excess heat from the CHP plant for energy-intensive processes is critical for maintaining the flexibility of the integrated thermochemical processes. Thermochemical processes integrated with CHP plants were able to operate on approximately 180 days of the year by utilizing only excess heat from the CHP plant. Integration of pyrolysis showed more flexibility than integration of gasification. Onsite hydrogen production was the main limiting factor for the integration of thermochemical process with the existing CHP plant to produce drop-in biofuels. Hydrogen produced with a solid oxide electrolysis cell (SOEC) decreased the overall system efficiency and limited the capacity of the overall process. However, hydrogen production from a water gas shift (WGS) reactor was more expensive. The results also indicated that small changes in the financial parameters have a large impact on the economic performance of the integrated process. 

  • 131.
    Salman, Chaudhary Awais
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Uncertainty and influence of input parameters and assumptions on the design and analysis of thermochemical waste conversion processes: A stochastic approach2020In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 214, article id 112867Article in journal (Refereed)
    Abstract [en]

    Process design is a challenging task for researchers and engineers. Incomplete information and variation in input data affect the outputs and reliability of key performance indicators (KPIs) of the designed process. The efficient utilization of waste is becoming increasingly important, and researchers use simulation and modelling tools for design and assessment of waste conversion processes. The complex nature of modelling of waste conversion processes and uncertainty of technical and financial data result in substantial variation in the KPIs of the designed process. In this study, we identified the critical parameters and assumptions that cause uncertainty in the process design analysis of waste-to-biofuels conversions. We used a stochastic modelling approach to address these methodological challenges and performed Monte Carlo simulations on waste-to-biofuel processes. The identified uncertain parameters and inputs were varied for a whole year with a one-minute time step. Different thermochemical conversion pathways were modelled by varying uncertain inputs and assumptions over the year by applying Monte Carlo simulations. Variations in the system's technical and economic KPIs were observed and compared. The results show that the heterogeneous nature of waste is a highly sensitive parameter, and a small change in its elemental analysis varies the technical performance significantly. Similarly, operating hours, plant size, capital investment, waste, and biofuel price are also very influential parameters on process design. Furthermore, the feasibility of waste-to-biofuel systems depends largely on how researchers and engineers select these parameters. Overall, the results reveal that by including the uncertainty of input parameters and assumptions in process design, the biases in results could be addressed transparently, making the overall assessment more reliable. 

  • 132.
    Schwede, Sebastian
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Bruchmann, Florian
    Ruhr-University, Bochum, Germany.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Gerber, Mandy
    Bochum University of Applied Sciences, Bochum, Germany.
    Biological syngas methanation via immobilized methanogenic archaea on biochar2017In: Energy Procedia, ISSN 1876-6102, Vol. 105, p. 823-829Article in journal (Refereed)
    Abstract [en]

    Syngas containing H2, CO, CO2 and CH4 produced by thermalprocesses such as gasification or pyrolysis is typically converted to methane via thermochemical methanation. This process is characterized by a high heat demand utilizing a sensitive chemical catalyst at increased pressure conditions. Alternatively, methanogenic archaea could be exploited as a naturalcatalyst in a biological methanation process with a lower energy demand. However, the mass transfer between the gas phase and the microbial cell is a major challenge for efficient conversion of the syngas components. Therefore, in this work methanogenic archaeafrom anaerobic digestion residueswere successfully immobilized on biochar particles obtained from green waste pyrolysis with two distinct particle sizes (0.25-1 mm and 1-2 mm). After incubation of the inoculated particles with an artificial syngas mixture CH4 was formed within the first 24 hours, while H2, CO2 and CO simultaneously declined. However, the particle size had no influence on the CH4 yield, content and conversion efficiency. According to the maximum theoretical conversion rate of H2 with CO2 and CO to CH4 only about 50% of the syngas components were converted to methane. These results suggest that CO was rather utilized by the methanogens involved for acetate/formate formation than for methanogenesis due to slight inhibition of the latter processby CO present in the syngas. The impact of CO inhibition during biological syngas methanation needs to be further evaluated for a continuous application of the process. However, a proof of concept for this process using inoculated biochar particles could be shown within the study presented here.

  • 133.
    Schwede, Sebastian
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Effect of municipal solid green waste derived biochar on anaerobic digestion2017Conference paper (Refereed)
    Abstract [en]

    Biochar as a soil amendment has the potential to sequester carbon dioxide from the atmosphere and improve crop yields by reducing nutrient leaching and increasing soil aeration and water holding capacity. Additional nutrients can be introduced into the soil by activation of the biochar with nutrient rich materials such as manure or digestion residues. Likewise, the anaerobic digestion performance might be affected by the biochar addition during the activation.

    This study investigates the effect of municipal solid green waste derived biochar on mesophilic anaerobic digestion in terms of particle size and amount of added biochar to the digestion of microcrystalline cellulose. Both, particle size and biochar concentration, affected the methane yield and degradation kinetics. While small particles (0.125-0.25 mm) had a slight negative effect, both middle- (0.5-1 mm) and high-sized (2-4 mm) particles had a positive effect on the initial and final methane yield increasing with the concentration (1, 2.5 and 5 g L-1). The improvement of the initial methane yield could be attributed to the available colonialization area for microorganisms on the biochar, whereas the increased final methane yield was influenced by the own gas potential of the biochar. The results suggest that municipal solid green waste is a suitable feedstock for biochar production and the subsequent integration within the anaerobic digestion process chain.

  • 134.
    Schwede, Sebastian
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lindmark, Johan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Klintenberg, Patrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jääskelainen, A
    Savonia Univ Appl Sci, Environm Engn, Kuopio, Finland.
    Suhonen, A.
    Savonia Univ Appl Sci, Environm Engn, Kuopio, Finland.
    Laatikainen, R.
    Univ Eastern Finland, Sch Pharm, Kuopio, Finland.
    Hakalehto, E.
    Univ Eastern Finland, Sch Pharm, Kuopio, Finland.
    Using slaughterhouse waste in a biochemical-based biorefinery – results from pilot scale tests2017In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, p. 1275-1284Article in journal (Refereed)
    Abstract [en]

    A novel biorefinery concept was piloted using protein-rich slaughterhouse waste, chicken manureand straw as feedstocks. The basic idea was to provide a proof of concept for the production ofplatform chemicals and biofuels from organic waste materials at non-septic conditions. Thedesired biochemical routes were 2,3-butanediol and acetone–butanol fermentation. The resultsshowed that hydrolysis resulted only in low amounts of easily degradable carbohydrates.However, amino acids released from the protein-rich slaughterhouse waste were utilized andfermented by the bacteria in the process. Product formation was directed towards acidogeniccompounds rather than solventogenic products due to increasing pH-value affected by ammoniarelease during amino acid fermentation. Hence, the process was not effective for 2,3-butanediolproduction, whereas butyrate, propionate,γ-aminobutyrate and valerate were predominantlyproduced. This offered fast means for converting tedious protein-rich waste mixtures intoutilizable chemical goods. Furthermore, the residual liquid from the bioreactor showedsignificantly higher biogas production potential than the corresponding substrates. Thecombination of the biorefinery approach to produce chemicals and biofuels with anaerobicdigestion of the residues to recover energy in form of methane and nutrients that can beutilized for animal feed production could be a feasible concept for organic waste utilization.

  • 135.
    Shinde, Amar Mohan
    et al.
    Manipal Acad Higher Educ, Manipal Inst Technol, Dept Civil Engn, Manipal 576104, Karnataka, India..
    Dikshit, Anil Kumar
    Indian Inst Technol, Dept Environm Sci & Engn, Mumbai, Maharashtra, India..
    Odlare, Monica
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Life cycle assessment of bio-methane and biogas-based electricity production from organic waste for utilization as a vehicle fuel2021In: Clean Technologies and Environmental Policy, ISSN 1618-954X, E-ISSN 1618-9558, Vol. 23, no 6, p. 1715-1725Article in journal (Refereed)
    Abstract [en]

    The concerns about climate change, energy security and price fluctuation of fossil fuels are driving the growing interest in the development and utilization of renewable energy as a transportation fuel. In this aspect, the utilization of organic household waste for the production of biogas avoids the environmental impact of landfills. The further upgrading and utilization of biogas as a vehicle fuel avoids the environmental impact of fossil fuels. This paper presents the life cycle assessment of two utilization pathways of biogas produced from co-digestion of organic household waste, grease trap removal sludge and ley crops grown by local farmers. Specifically, this study assessed and compared the environmental impact of the production and utilization of bio-methane and biogas-based electricity as a vehicle fuel for public transport buses in Vasteras, Sweden. The system boundary for biogas production covered seven main steps: cultivation, harvesting and transport of ley crops, collection and transport of waste, pre-treatment and co-digestion of the substrate. The system boundary for bio-methane was further extended to account for the upgrading process and tailpipe emissions from combustion of bio-methane in the buses. In the case of biogas-based electricity, the system boundary was further extended to account for the combustion of biogas in the CHP unit and further utilization of electricity in the electric bus. The evaluation of the production routes showed that the methane losses and high energy consumption for both biogas production and upgrading process dominated the environmental impact of bio-methane production. However, the emissions from the CHP unit were solely responsible for the environmental impact of biogas-based electricity production. The functional unit identified for this study is 1 vehicle km travelled (VKT) of the bio-methane fuelled bus and electric bus. The global warming potential of the electric buses was 0.11 kg CO2-eq/VKT compared to 0.26 kg CO2-eq/VKT for the bio-methane buses. The electric buses could also reduce about half of the acidification and eutrophication impacts associated with the bio-methane fuelled buses. The lower fuel efficiency and high tailpipe emissions decreased the environmental advantages of the bio-methane buses. Eventually, this study ensures the biogas utilization which is environmentally sound and compares favourably with the alternative options. [GRAPHICS] .

  • 136.
    Song, Han
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Dotzauer, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nordlander, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Modeling and optimization of a regional waste-to-energy system: A case study in central Sweden2013In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 33, no 5, p. 1315-1316Article in journal (Other academic)
  • 137.
    Starfelt, Fredrik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Daianova, Lilia
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinuye
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dotzauer, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Increased renewable electricity production in combined heat and power plants by introducing ethanol production2009Conference paper (Refereed)
    Abstract [en]

    The development towards high energy efficiency and low environmental impact by humaninteractions, has led to a change in many levels of society. Due to the introduction of penalties oncarbon dioxide emissions and other economic instruments, the energy industry is striving towardsenergy efficiency improvement and climate mitigation by switching from fossil to renewablefuels. Biomass-based combined heat and power (CHP) plants connected to district heatingnetworks have a need to find uses for excess heat to produce electricity during summer when theheat demand is low. On the other hand, the transport sector is contributing substantially to theincreased CO2 emissions, which have to be reduced. One promising alternative to address the twochallenging issues is the integration of vehicle fuel production with biomass based CHP plants. Inthis paper, the configuration and operation profits in terms of electricity, heat and ethanol fuelfrom cellulosic biomass are presented. A case study of a commercial small-scale CHP plant hasbeen carried out using simulation and modeling tools. The results clearly show that electricityproduction can be increased when CHP production is integrated with cellulosic ethanolproduction. The findings presented also show that the economical benefits of the energy systemcan be realized with near-term commercially available technology

  • 138.
    Starfelt, Fredrik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Daianova, Lilia
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dotzauer, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    The impact of lignocellulosic ethanol yields in polygeneration with district heating: A case study2012In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 92, p. 791-799Article in journal (Refereed)
    Abstract [en]

    The development towards high energy efficiency and low environmental impact from human interactions

    has led to changes at many levels of society. As a result of the introduction of penalties on carbon

    dioxide emissions and other economic instruments, the energy industry is striving to improve energy

    efficiency and climate mitigation by switching from fossil fuels to renewable fuels. Biomass-based combined

    heat and power (CHP) plants connected to district heating networks have a need to find uses for the

    excess heat they produce in summer when the heat demand is low. On the other hand, the transport sector

    makes a substantial contribution to the increasing CO

    2

    emissions, which have to be reduced. One

    promising alternative to address these challenging issues is the integration of vehicle fuel production

    with biomass-based CHP plants. This paper presents the configuration and operating profits in terms

    of electricity, heat and ethanol fuel from cellulosic biomass. A case study of a commercial small scale

    CHP plant was conducted using simulation and modeling tools. The results clearly show that electricity

    production can be increased when CHP production is integrated with cellulosic ethanol production. The

    findings also show that the economic benefits of the energy system can be realized with near-term commercially

    available technology, and that the benefits do not rely solely on ethanol yields.

  • 139.
    Starfelt, Fredrik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thorin, Eva
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dotzauer, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Performance evaluation of adding ethanol production into an existing combined heat and power plant2010In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 2, p. 613-618Article in journal (Refereed)
    Abstract [en]

    In this paper, the configuration and performance of a polygeneration system are studied by modelling the integration of a lignocellulosic wood-to-ethanol process with an existing combined heat and power (CHP) plant. Data from actual plants are applied to validate the simulation models. The integrated polygeneration system reaches a total efficiency of 50%, meeting the heating load in the district heating system. Excess heat from the ethanol production plant supplies 7.9MWto the district heating system, accounting for 17.5% of the heat supply at full heating load. The simulation results show that the production of ethanol from woody biomass is more efficient when integrated with a CHP plant compared to a stand-alone production plant. The total biomass consumption is reduced by 13.9% while producing the same amounts of heat, electricity and ethanol fuel as in the stand-alone configurations. The results showed that another feature of the integrated polygeneration system is the longer annual operating period compared to existing cogeneration. Thus, the renewable electricity production is increased by 2.7% per year.

  • 140.
    Starfelt, Fredrik
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Tomas Aparicio, Elena
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Ericson, V.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Simultaneous dynamic and quasi-steady state simulations to optimize combined heat and power plant operation2012Conference paper (Refereed)
  • 141.
    Sun, Yingying
    et al.
    Tianjin Univ Commerce, Tianjin, Peoples R China..
    Dong, Beibei
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin Univ Commerce, Tianjin, Peoples R China..
    Wang, Liang
    SINTEF Energy Res, Trondheim, Norway..
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Technology selection for capturing CO2 from wood pyrolysis2022In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 266, article id 115835Article in journal (Refereed)
    Abstract [en]

    Emerging negative emission technologies (NETs) are considered as effective measures to reduce carbon dioxide emissions to achieve the climate goal set by the Paris Agreement, and bioenergy with carbon capture and storage (BECCS) is one of the most important NETs. Integrating CO2 capture with biomass pyrolysis (PyrCC) is attracting increasing interest, because biomass pyrolysis has been widely used to produce biooil to replace fossil fuel for decarbonizing the transport sector. In order to provide guidance to the selection of CO2 capture technologies, this paper evaluated the technical and economic performances of PyrCC when different CO2 capture technologies are integrated, including monoethanolamine-based chemical absorption (MEA-CA), temperature swing absorption (TSA), calcium looping (CaL), and chemical looping combustion (CLC). Generally speaking, CLC can realize the highest capture amount of CO2 with the lowest energy penalty. Meanwhile, CLC and CaL show the lowest levelized cost of CO2 (LCOC), which are around 56$/tCO(2); and on the contrary MEA-CA shows the highest one of 83 $/tCO(2). In addition, the key process parameter of pyrolysis, reaction time, has clear effects on the performance of CO2 capture as the longer reaction time leads to an increased amount of captured CO2 and reduced energy penalty. As a result, when the reaction time increases, the LCOCs of all assessed technologies decrease. Moreover, the net present value and the payback time are also estimated for different technologies. At the carbon price of 70.1$/tCO(2), MEA-CA and CLC show the longest and shortest payback time that are 5.9 years and 3.2 years respectively.

  • 142.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Bergna, Davide
    Univ Oulu, Res Unit Sustainable Chem, POB 8000, FI-90014 Oulu, Finland..
    Runtti, Hanna
    Univ Oulu, Res Unit Sustainable Chem, POB 8000, FI-90014 Oulu, Finland..
    Westholm, Lena Johansson
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Primary and digested sludge-derived char as a Cd sorbent: feasibility of local utilisation2023In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 11, p. 2917-2930Article in journal (Refereed)
    Abstract [en]

    Cadmium (Cd) is a highly toxic metal, occurring in municipal wastewater and stormwater as well as in wastewater from various industries. Char derived from the pyrolysis of municipal sewage sludge has the potential to be a low-cost sorption media for the removal of Cd. However, the balance between possible local char production and demand has not been assessed previously. In this study, the Cd sorption capacities of chars derived from primary (PSC) and secondary sludge (DSC), as well as the feasibility of char production for Cd sorbent purposes, and the pyrolysis energy balance were evaluated. Results showed that the sorption capacity of PSC (9.1 mg/g; 800 degrees C, 70 min) was superior to that of DSC (6.0 mg/g; 800 degrees C, 70 min), and increased with a higher pyrolysis temperature. Pyrolysis of primary sludge had a more favourable energy balance compared with the pyrolysis of digested sludge, however, when accounting for loss of biogas production the energy balance of primary sludge pyrolysis was negative. Assessment of the regional demand (V & auml;ster & aring;s, Sweden) indicated that PSC or DSC may cover the local Cd sorbent demand. However, it was estimated that large char volumes would be required, thus making the use of DSC/PSC less feasible.

  • 143.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zambrano, Jesús
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Removal of metals for improvement of sludge quality, adsorption to primary sludge during primary settlement2017Conference paper (Other academic)
    Abstract [en]

    The primary and secondary sludge from a wastewater treatment plant are generally mixed and treated combined. Here we introduce an idea for a process concept where the sludge flows are separated and the treatment of primary sludge is modified, with the goal to concentrate micropollutants in primary sludge while nutrients are removed in the secondary (biological) treatment to produce a “bio-sludge” with low metal contents. The example is based on primary settlement and an activated sludge process. In contrast to a conventional process, the sludge flows are as mentioned separated. After anaerobic digestion and dewatering, primary sludge goes through pyrolysis. Biochar produced during pyrolysis is added in pulverized or granulated form to the primary settler. The hypothesis is that biochar will adsorb dissolved metals and thus enhance the metal removal in primary treatment. The biochar should settle with primary sludge, and pyrolysis is repeated. However, to remove metal content from the system some portion of the produced biochar will have to be removed in each cycle. A prerequisite for nutrients to end up in the bio-sludge is that chemical coagulants are not used in primary treatment and that there is no recirculation of sludge from secondary to primary treatment. To the best of the authors knowledge, biochar has not previously been tested as an adsorbent in primary treatment of wastewater. Efficient removal of metals has though been shown in several studies where wastewater was filtrated through biochar in granulated form (Huggins et al., 2016). Further, biochar has been shown to sorb pharmaceuticals from urine without removing nutrients (Solanki & Boyer, 2017). In this paper, results from experimental tests on addition of biochar in the primary settler will be presented. Experiments are made in lab-scale to test the adsorption and settling capacity depending on biochar properties, e.g. particle size, cation exchange capacity. The theoretical dosing requirement in a full scale application and possible biochar yields from pyrolysis of primary sludge are also investigated.

  • 144.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Runtti, Hanna
    Oulu University, Finland.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zambrano, Jesus
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Westholm, Lena Johansson
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    BIOCHAR ADSORPTION FOR SEPARATION OF HEAVY METALSIN MUNICIPAL WASTEWATER TREATMENT2018Conference paper (Other academic)
  • 145.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Runtti, Hanna
    School of Business, Society and Engineering, Future Energy Center, Mälardalen University, P.O. Box 883, Västerås, SE-721 23, Sweden.
    Westholm, Lena Johansson
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Romar, H.
    Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 8000, Oulu, FI-90014, Finland.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Heavy metal sorption by sludge-derived biochar with focus on Pb2+ sorption capacity at µg/L concentrations2020In: Processes, ISSN 2227-9717, Vol. 8, no 12, p. 1-23, article id 1559Article in journal (Refereed)
    Abstract [en]

    Municipal wastewater management causes metal exposure to humans and the environment. Targeted metal removal is suggested to reduce metal loads during sludge reuse and release of effluent to receiving waters. Biochar is considered a low-cost sorbent with high sorption capacity for heavy metals. In this study, heavy metal sorption to sludge-derived biochar (SDBC) was investigated through batch experiments and modeling and compared to that of wood-derived biochar (WDBC) and activated carbon (AC). The aim was to investigate the sorption efficiency at metal concentrations comparable to those in municipal wastewater (<1 mg/L), for which experimental data are lacking and isotherm models have not been verified in previous works. Pb2+ removal of up to 83% was demonstrated at concentrations comparable to those in municipal wastewater, at pH 2. SDBC showed superior Pb2+ sorption capacity (maximum ~2 mg/g at pH 2) compared to WDBC and AC (<0 and (3.5 ± 0.4) × 10−3 mg/g, respectively); however, at the lowest concentration investigated (0.005 mg/L), SDBC released Pb2+. The potential risk of release of other heavy metals (i.e., Ni, Cd, Cu, and Zn) needs to be further examined. The sorption capacity of SDBC over a metal concentration span of 0.005–150 mg Pb2+/L could be predicted with the Redlich– Peterson model. It was shown that experimental data at concentrations comparable to those in municipal wastewater are necessary to accurately model and predict the sorption capacity of SDBC at these concentrations. 

  • 146.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Potential of sludge-derived char as a metal sorbent during primary settling of municipal wastewater2023In: Environmental Technology & Innovation, ISSN 2352-1864, Vol. 32, article id 103258Article in journal (Refereed)
    Abstract [en]

    Reuse of nutrients and water from municipal wastewater is attracting increasing attention. However, pollutants such as toxic metals should be minimised. This study investigated the potential for reducing metal concentrations in wastewater effluent and secondary sludge by introducing sludge-derived char (SDC) as a sorbent in primary settling. Batch experiments, performed in aqueous metal solution and wastewater, showed that Cu and Ni removal was significantly reduced in wastewater containing dissolved organic matter (68% and 40%, respectively), compared to metal solution (>99% and 99%, respectively). Modelling of primary settling indicated Cd and Cu removal enhancement with SDC addition (from 39%–79% and 30%–43%, respectively). Smaller effects were observed for Pb, Cr, and Zn. An increased risk of Ni concentration in primary settler effluent was identified (−53% removal). These results demonstrate the challenges of implementing SDC as a sorbent for real wastewater.

  • 147.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Removal of heavy metals during primary treatment of municipal wastewater and possibilities of enhanced removal: A review2021In: Water, E-ISSN 2073-4441, Vol. 13, no 8, article id 1121Article in journal (Refereed)
    Abstract [en]

    Resource reuse has become an important aspect of wastewater management. At present, use of sludge in agriculture is one of the major reuse routes. Conventional municipal wastewater treatment does not involve any designated process for removal of heavy metals, and these distribute mainly between effluent and sludge. Enhanced removal of heavy metals during primary treatment may decrease the heavy metal concentrations in both effluent and sludge from secondary treatment and promote long-term reuse of secondary sludge. This review considers heavy metal occurrence and removal during primary settling, together with possible treatment technologies for heavy metal removal in primary settlers and their theoretical performance. The variation in total heavy metal concentrations and dissolved fraction in raw municipal wastewater points to a need for site-specific assessments of appropriate technologies for improved heavy metal removal. Studies examining the heavy metal speciation beyond dissolved/particulate are few. Missing or disparate information on process parameters such as hydraulic retention time, pH and composition of return flows makes it hard to generalize the findings from studies concerning heavy metal removal in primary settlers. Coagulation/flocculation and use of low-cost sorbents were identified as the most promising methods for enhancing heavy metal removal during primary settling. Based on the available data on heavy metal speciation and removal during primary settling, sorption technologies may be most effective for enhancing the removal of Cu and Ni, while coagulation may be efficient for Cd, Cr, Cu, Pb, Zn and Hg removal (but not as efficient for Ni removal). 

  • 148.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Sludge-derived char - potential as a heavy metal sorbent during primary settling of municipal wastewater2022Conference paper (Other academic)
  • 149.
    Sylwan, Ida
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zambrano, Jesus
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Energy demand for phosphorus recovery from municipal wastewater2019In: Innovative Solutions for Energy Transitions / [ed] Elsevier, 2019, Vol. 158, p. 4338-4343Conference paper (Refereed)
    Abstract [en]

    Phosphorus (P) is one of the essential nutrients for production of food. In modern agriculture, a large part of P comes from finite sources. There are several suggested processes for reuse of P from wastewater. In this paper, the energy use of direct reuse of sludge in agriculture is compared to the energy demand connected to use of mineral P and to reuse of P after thermal processing of sludge. The study is based on literature data from life cycle analysis (LCA). In the case of direct sludge reuse the sludge stabilization processes applied and the system boundaries of the LCA has a large impact on the calculated energy demand. The results though indicate that direct reuse of sludge in agriculture is the reuse scenario that potentially has the lowest energy demand (3-71 kWh/kg P), compared to incineration and extraction of P from sludge ashes (45-70 kWh/kg P) or pyrolysis of sludge (46-235 kWh/kg P). The competitiveness compared to mineral P (-4-22 kWh/kg P) depends on the mineral P source and production. For thermal processing, the energy demand derives mainly from energy needed to dry sludge and supplement fuel used during sludge incineration together with chemicals required to extract P. Local conditions, such as available waste heat for drying, can make one of these scenarios preferable.

  • 150.
    Tan, Y.
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Nookuea, Worrada
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Royal Institute of Technology, Stockholm, Sweden.
    Cryogenic technology for biogas upgrading combined with carbon capture-a review of systems and property impacts2017In: Energy Procedia, ISSN 1876-6102, Vol. 142, p. 3741-3746Article in journal (Refereed)
    Abstract [en]

    CO2 makes a major contribution to the climate change, and biomass renewable energy and carbon capture and storage (CCS) can be deployed to mitigate the CO2 emission. Cryogenic process for biogas upgrading combined with carbon capture is one of the most promising technologies. This paper reviewed the state-of-the-art of cryogenic systems for biogas upgrading combined with carbon capture, and introduced the status and progress of property impacts on the cryogenic systems with emphasize on phase equilibrium. The existing cryogenic systems can be classified as flash liquefaction system, distillation system, and liquefaction combined with desublimation system. The flash liquefaction system produces biomethane and CO2 in lower purity than the other two systems. Thermodynamic optimization on the flash liquefaction system and liquefaction combined with desublimation system should be done further, and comprehensive comparison between three cryogenic systems needs to be carried out. As to the phase equilibrium, PR EOS is safe to be used in predicting VLE and SVLE with an independent thermodynamic model describing the fugacity of the solid phase. However, the impacts of binary mixing parameter, different EOS models and mixing rules, on the performance of the cryogenic system need to be identified in the future. 

1234 101 - 150 of 185
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf