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  • 1.
    Anbalagan, Anbarasan
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jeanette Castro, Cynthia
    University of Massachusetts Amherst, US.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lindberg, Carl-Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB Corporate Research, Sweden.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Northvolt AB, Sweden.
    Butler, Caitlyn
    University of Massachusetts Amherst, US.
    Influence of environmental stress on the microalgal-bacterial process during nitrogen removalManuscript (preprint) (Other academic)
  • 2.
    Anbalagan, Anbarasan
    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.
    Lindberg, Carl Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB, Corporate Research, Västerås, Sweden.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Influence of hydraulic retention time on indigenous microalgae and activated sludge process2016In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 91, p. 277-284Article in journal (Refereed)
    Abstract [en]

    Integration of the microalgae and activated sludge (MAAS) process in municipal wastewater treatment and biogas production from recovered MAAS was investigated by studying the hydraulic retention time (HRT) of semi-continuous photo-bioreactors. An average total nitrogen (TN) removal efficiency (RE) of maximum 81.5 ± 5.1 and 64.6 ± 16.2% was achieved at 6 and 4 days HRT. RE of total phosphorous (TP) increased slightly at 6 days (80 ± 12%) HRT and stabilized at 4 days (56 ± 5%) and 2 days (55.5 ± 5.5%) HRT due to the fluctuations in COD and N/P mass ratio of the periodic wastewater. COD and organic carbon were removed efficiently and a rapidly settleable MAAS with a sludge volume index (SVI_10) of less than 117 mL g-1 was observed at all HRTs. The anaerobic digestion of the untreated MAAS showed a higher biogas yield of 349 ± 10 mL g VS-1 with 2 days HRT due to a low solids retention time (SRT). Thermal pretreatment of the MAAS (120 °C, 120 min) did not show any improvement with biogas production at 6 days (269 ± 3 (untreated) and 266 ± 16 (treated) mL gVS-1), 4 days (258 ± 11(untreated) and 263 ± 10 (treated) mL gVS-1) and 2 days (308 ± 19 mL (treated) gVS-1) HRT. Hence, the biogas potential tests showed that the untreated MAAS was a feasible substrate for biogas production. Results from this proof of concept support the application of MAAS in wastewater treatment for Swedish conditions to reduce aeration, precipitation chemicals and CO2 emissions. 

  • 3.
    Anbalagan, Anbarasan
    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.
    Lindberg, Carl-Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Continuous microalgae-activated sludge flocs for remediation of municipal wastewater under low temperature2017In: / [ed] Peter Van der Steen, 2017, p. 1-8Conference paper (Refereed)
    Abstract [en]

    The operational performance of indigenous microalgae-activated sludge was evaluated regarding the nutrient removal efficiency using raw wastewater collected from Västerås wastewater treatment plant, Sweden at limited artificial surface lighting (290 μmol m-1 sec-1) and Nordic wastewater conditions (13°C). Additionally, the oxygen production and consumption, biomass concentration and its settling was evaluated during the symbiotic algal-bacterial interaction. The results confirmed oxygenic organic compound removal (COD removal of 65-94%) at higher (31-45 d) and lower (13-18 d) sludge retention time (SRT). Also, a complete removal of ammonium throughout the process and partial nitrite-nitrate removal at all SRTs (total nitrogen removal of 41- 62%) were observed. Likewise, a partial phosphorus (P)removal was observed in the effluent which provides an opportunity to capture free P fromthe effluent for recovery as fertiliser. Further, the microalgal growth was slower due to lightor inorganic carbon limitation or ammonium repression caused by higher internal recirculationas observed from ammonium and nitrite-nitrate levels in the PBR. Most importantly, effectivePBR biomass concentration based nutrient removal and relative sludge recirculation have tobe considered in the PBR design to avoid light limitation and activate symbiosis.

  • 4.
    Anbalagan, Anbarasan
    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.
    Lindberg, Carl-Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB, Corporate Research, Västerås, Sweden.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Influence of iron precipitated condition and light intensity on microalgae activated sludge based wastewater remediation2017In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, p. 1523-1530Article in journal (Refereed)
    Abstract [en]

    The indigenous microalgae-activated sludge (MAAS) process during remediation of municipal wastewater was investigated by studying the influence of iron flocculation step and light intensity. In addition, availability of total phosphorous (P) and photosynthetic activity was examined in fed-batch and batch mode under northern climatic conditions and limited lighting. This was followed by a semi-continuous operation with 4 d of hydraulic retention time and mean cell residence time of 6.75 d in a photo-bioreactor (PBR) with varying P availability. The fed-batch condition showed that P concentrations of 3–4 mg L−1 were effective for photosynthetic chl. a development in iron flocculated conditions. In the PBR, the oxygen evolution rate increased with increase in the concentration of MAAS (from 258 to 573 mg TSS L−1) at higher surface photosynthetic active radiation (250 and 500 μmol m−2 s−1). Additionally, the rate approached a saturation phase at low MAAS (110 mg L−1) with higher light intensities. Semi-continuous operation with luxury P uptake and effective P condition showed stable average total nitrogen removal of 88 and 92% respectively, with residual concentrations of 3.77 and 2.21 mg L−1. The corresponding average P removal was 68 and 59% with residual concentrations of 2.32 and 1.75 mg L−1. The semi-continuous operation produced a rapidly settleable MAAS under iron flocculated condition with a settling velocity of 92–106 m h−1 and sludge volume index of 31–43 ml g−1 in the studied cases.

  • 5.
    Anbalagan, Anbarasan
    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.
    Influence of light emitting diodes on indigenous microalgae cultivation in municipal wastewater2015In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 75, p. 786-792Article in journal (Refereed)
    Abstract [en]

    In this study, the effect of light emitting diodes (LEDs) on microalgae cultivation in municipal wastewater was examined in comparison to the fluorescent light. Two kinds of wastewater were evaluated: first one with low concentration of total phosphorous (TP) and second one with high TP concentration. The nutrient removal and biomass production using LEDs is efficient at photo-synthetically active radiation (PAR) intensity of 107-112 mu mol m(-2) s(-1) which is slightly higher than fluorescent light. Furthermore, this study demonstrates the applicability and distribution of light in wastewater where the environment is not defined. More importantly, winter and rainy periods contribute to dark condition and dilution of wastewater, intense LED light offers a feasible option for the functioning of closed micro algae based activated sludge (MAAS) process for recovery and reuse of nutrients. 

  • 6.
    Andersson, Henny
    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.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jansson, Joakim
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Suhonen, Anssi
    Savonia University of Applied Sciences.
    Jääskeläinen, Ari
    Savonia University of Applied Sciences.
    Reijonen, Tero
    Savonia University of Applied Sciences.
    Laatikainen, Reino
    University of Eastern Finland.
    Heitto, Anneli
    Finnoflag.
    Hakalehto, Elias
    Finnoflag.
    Technical Output Report – Pilot A in Sweden2014Report (Other academic)
  • 7. Andersson, Henny
    et al.
    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.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jansson, Joakim
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Suhonen, Anssi
    Savonia University of Applied Sciences, University of Eastern Finland, Finland.
    Jääskeläinen, Ari
    Savonia University of Applied Sciences, University of Eastern Finland, Finland.
    Reijonen, Tero
    Laatikainen, Reino
    Heitto, Anneli
    Hakalehto, Elias
    TECHNICAL REPORT ON PILOT A TESTS IN SWEDEN2015Report (Refereed)
  • 8.
    Hakalehto, E.
    et al.
    University of Helsinki, Helsinki, Finland.
    Heitto, A.
    University of Helsinki, Helsinki, Finland.
    Andersson, Henny
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lindmark, Johan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jansson, Joakim
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Reijonen, T.
    Savonia University of Applied Sciences, Kuopio, Finland.
    Suhonen, A.
    Savonia University of Applied Sciences, Kuopio, Finland.
    Jääskeläinen, A.
    Savonia University of Applied Sciences, Kuopio, Finland.
    Laatikainen, R.
    University of Eastern Finland, Kuopio, Finland.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Klintenberg, Patrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thorin, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Some remarks on processing of slaughterhouse wastes from ecological chicken abattoir and farm2016In: Microbiological Industrial Hygiene, Nova Science Publishers, Inc. , 2016, p. 271-293Chapter in book (Other academic)
    Abstract [en]

    In the meat industries, it is always of high importance to follow up the zoonotic and other hazardous micro-organisms, and to prevent their risky distribution, emission and dissemination. Besides proper hygiene control, as well as organized exploitation of the side streams and slaughterhouse wastes helps in the hygienization of the biomasses, processes, and the entire industry. During this experimentation it turned out that it was possible to produce gases and chemical goods, not only from the carboxylates, but also from the more tedious protein and lipid containing wastes. Moreover, these promising results were obtained from a substrate mix with manure and wood chips. These results implied to the high versatility and flexibility of the bioprocess during Pilot A tests within the European Union Baltic Sea region project ABOWE. In Sweden these tests were carried out using the combined wastes from the ecological chicken farm and abattoir as the raw materials. This is a report of the practical set up during intensive experimentation conducted jointly by the Swedish and Finnish personnel. The report of the runs in Sweden is presented also in the public report of the European Union funded project (www.abowe.eu).

  • 9.
    Huopana, Tuomas
    et al.
    University of Eastern Finland, Finland.
    Niska, Harri
    University of Eastern Finland, Finland.
    Kolehmainen, Mikko
    University of Eastern Finland, Finland.
    Jääskeläinen, Ari
    Savonia University of Applied Sciences, Finland.
    Antikainen, Eero
    Savonia University of Applied Sciences, Finland.
    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.
    Klintenberg, Patrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Hakalehto, Elias
    Finnoflag, Finland.
    Ahrens, Thorsten
    Ostfalia University of Applied Sciences, Germany.
    Sustainability assessment of biorefinery and dry digestion systems: Case:Sweden2014Report (Other academic)
  • 10.
    Li, Hailong
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Wang, Bin
    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 Royal Institute of Technology, Stockholm, Sweden.
    Salman, Chaudhary Awais
    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.
    Performance of flue gas quench and its influence on biomass fueled CHP2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 180, p. 934-945Article in journal (Refereed)
    Abstract [en]

    For biomass/waste fueled power plants, stricter regulations require a further reduction of the negative impacts on the environment caused by the release of pollutants and withdrawal of fresh water externally. Flue gas quench (FGQ) is playing an important role in biomass or waste fueled combined heat and power (CHP) plants, as it can link the flue gas (FG) cleaning, energy recovery and wastewater treatment. Enhancing water evaporation can benefit the concentrating of pollutant in the quench water; however, when FG condenser (FGC) is not in use, it results in a large consumption of fresh water. In order to deeply understand the operation of FGQ, a mathematic model was developed and validated against the measurements. Based on simulation results key parameters affecting FGQ have been identified, such as the flow rate and temperature of recycling water and the moisture content of FG. A guideline about how to reduce the discharge of wastewater to the external and the withdrawal of external water can be proposed. The mathematic model was also implemented into an ASPEN Plus model about a CHP plant to assess the impacts of FGQ on CHP. Results show that when the FGC was running, increasing the flow rate and decreasing the temperature of recycling water can result in a lower total energy efficiency. 

  • 11.
    Li, Xueqiang
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin University of Commerce, Tianjin, China.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin University of Commerce, Tianjin, China.
    Yu, X.
    University of Shanghai for Science and Technology, Shanghai, China.
    Yu, Z.
    University of Stavanger, Stavanger, Norway.
    Zhu, K.
    Tianjin University, Tianjin, China.
    Toxicity of ionic liquid on anaerobic digestion2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 938-942Article in journal (Refereed)
    Abstract [en]

    Anaerobic digestion is a straightforward process to produce energy from biomass. However, the lignin composed of phenylpropanoid units induces a strong resistance for the hydrolysis step. Ionic liquids (ILs) have been applied in biomass pretreatment to dissolve the biomass components and enhance the anaerobic digestion. However, there are still some challenges such as the toxicity. ILs could inhibit the digestion process and reduce the CH4 production. In this work, a toxicity test for [BMIM]Cl (1-chlorobutane and N-methylimidazole) was conducted. Results show that IL has a strong inhibition and lowered CH4 production when its concentration was higher. At 0.2305±0.0116 g L-1 and 0.4367±0.0219 g L-1, the anaerobic digestion process was inhibited by 10 and 50%, respectively. Accordingly, a higher recovery ratio or a lower pretreatment ratio are necessary to avoid the negative impact of inhibition on BMP. 

  • 12.
    Lu, H.
    et al.
    School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, China.
    Yu, X.
    School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Tu, S. -T
    School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, China.
    Accurately measurement and efficiently recovery of ionic liquid in energy utilization of microalgae2019In: Energy Procedia, Elsevier Ltd , 2019, Vol. 158, p. 1337-1341Conference paper (Refereed)
    Abstract [en]

    Chlorella vulgais, a kind of micro-alagae, is an attracting feedstock for bioenergy production, such as biodiesel and biogas. But its tough cell wall structure is the main obstacle to efficiently extracting lipids and other biomass. Ionic liquid (IL) can be used to hydrolyze its cell-wall. However, due to its high cost and toxicity, it is important to recover IL as much as possible. Therefore, a method that can accurately measure the content of ILs, is urgently needed. In this work, two common methods that are used to measure the content of ILs: equimolar titration method and ultraviolet absorbance spectra were compared. The results show that equimolar titration method is not available for trace quantity analysis of ionic liquids as the endpoint of titration is hard to be identified at low IL content (<10 mg/L); while UV absorbance spectra method can be used at low IL contents, whereas, it may result in big deviations. To further improve the accuracy of UV absorbance spectra method, concentrating the sample could be a potential solution.

  • 13.
    Lu, H.
    et al.
    East China University of Science and Technology, Shanghai, China.
    Yu, X.
    East China University of Science and Technology, Shanghai, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Tu, S. -T
    East China University of Science and Technology, Shanghai, China.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lipids extraction from wet Chlorella pyrenoidosa sludge using recycled [BMIM]Cl2019In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 291, article id 121819Article in journal (Refereed)
    Abstract [en]

    In this study, experiments on pretreating one species of microalgae (Chlorella pyrenoidosa) using one kind of ionic liquid (IL) of [BMIM]Cl were conducted. The aim of this work is to evaluate the recycling efficacy of expensive IL solvent for effective cell disruption. It was indicated that the molecular structure of IL was stable during the recycling test. Five times antisolvent precipitation of microalgae debris after lipid extraction using methanol recovered 99.8% IL with the energy consumption of 4.46 MJ per kg dry Chlorella pyrenoidosa. The chromatography was used to separate IL and hydrolysates, resulting in the IL loss below 1.97 g per kg dry Chlorella pyrenoidosa. © 2019 Elsevier Ltd

  • 14.
    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.

  • 15.
    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.

  • 16.
    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 sludgeIn: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732Article in journal (Refereed)
  • 17.
    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. 

  • 18.
    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.

  • 19.
    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.

  • 20.
    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.

  • 21.
    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.

  • 22.
    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.

  • 23.
    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, E-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.

  • 24.
    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.

  • 25.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Investigation of mutual antagonism in the presence of sodium and ammonia during anaerobic digestion2015Conference paper (Refereed)
  • 26.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Microbial Community, Its Maintenance and Raw Material Composition in Biogas Production Units2016In: Microbiological Industrial Hygiene, Nova Science Publishers, Inc., 2016Chapter in book (Refereed)
    Abstract [en]

    Anaerobic digestion is a widely applied process to recover energy and nutrients duringthe stabilization of organic waste or to produce a renewable energy carrier in form of biogasfrom various organic materials. The process application ranges from simple householdscale to complex industrial scale systems to produce a methane-rich biogas that can beutilized for heating and cooking, electricity and heat provision or a replacement of naturalgas.The anaerobic digestion process is a natural process conducted by various microbialgroups in oxygen-free environments. The consecutive process phases during thedecomposition of organic matter to biogas are characterized by so-called syntrophicrelationships, where all involved microbial groups depend on successful collaborationalong the various process phases. However, not all microbial groups share the samerequirements to their environments imposing compromises on some groups to maintainphysiological activity of the total system. Additionally, some microbial groups are moresensitive to inhibitory compounds that might be introduced into the process with theorganic material or formed during the degradation. The maintenance of suitable conditionsfor all involved microbial groups is the major challenge especially during anaerobicdigestion at industrial scale, where consistent treatment or production efficiency isrequired. The following chapter provides the basis to understand the microbialinterrelationships and process conditions to exploit anaerobic digestion as an economicallyand ecologically beneficial technology.

  • 27.
    Schwede, Sebastian
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Anbalagan, Anbarasan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Krustok, Ivo
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lindberg, Carl-Fredrik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB Corporate Research, Västerås, Sweden.
    Nehrenheim, Emma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Evaluation of the microalgae-based activated sludge (MAAS) process for municipal wastewater treatment on pilot scale2016Conference paper (Refereed)
    Abstract [en]

    The microalgae-based activated sludge (MAAS) process was evaluated regarding the removal efficiency of organic matter and nitrogen from physiochemically pretreated municipal wastewater at different hydraulic retention time (HRT) on pilot scale. Additionally, the interplay between the algal and bacterial consortium was evaluated regarding the ability of the algal consortium to provide oxygen for bacterial oxidation processes. The results showed in general high organic matter (COD removal 75-90%) and total nitrogen (40-50%) removal at all HRTs (6, 4 and 2 days). The dissolved oxygen (DO) concentration was maintained stable at 6 days (6.04±0.47 mg L-1) and 4 days (4.24±0.62 mg L-1) HRT. However, the DO significantly declined at 2 days HRT due to loss of biomass at the high influent flow in the sedimentation unit. Nevertheless, the MAAS process functioned as a symbiotic algal-bacterial system with bacterial organic matter oxidation and nitrification and algal nutrient removal.

  • 28.
    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, E-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.

  • 29.
    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.

  • 30.
    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.

  • 31.
    Thorin, Eva
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lindmark, Johan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Freidank, Tim
    Ostfalia University of Applied Sciences.
    Drescher-Hartung, Silvia
    Ostfalia University of Applied Sciences.
    Daukšys, Vygintas
    Klaipeda University.
    Ahrens, Thorsten
    Ostfalia University of Applied Sciences.
    POSSIBILITES FOR OPTIMIZATION OF THE DRY DIGESTION PROCESS2014Report (Other academic)
  • 32.
    Thorin, Eva
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nordlander, 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.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Jansson, Joakim
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Hakalehto, Elias
    Finnoflag.
    Heitto, Anneli
    Finnoflag.
    Jääskeläinen, Ari
    Savonia University of Applied Sciences.
    Suhonen,, Anssi
    Savonia University of Applied Sciences.
    Den Boer, Emilia
    Wrocław University of Technology.
    Possibilites for Optimization of Biorefinery process2014Report (Other academic)
  • 33.
    Thorin, Eva
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Olsson, Jesper
    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.
    Biogas from Co-digestion of Sewage Sludge and Microalgae2017In: Energy Procedia, 2017, Vol. 105, p. 1037-1042Conference paper (Refereed)
    Abstract [en]

    Microalgae cultivated in waste water could contribute to increased biomass production at municipal waste watertreatment plants. The biomass could be utilized for biogas production when co-digested with sewage sludge. In thispaper previous published results on co-digestion of sewage sludge and microalgae are summarized and remainingknowledge gaps are identified. The available batch tests in literature mostly concern digestion at mesophilicconditions. Some of those tests indicate a synergetic effect for the co-digestion. Investigations at thermophilicconditions and of semi-continuous processes are scarce. The available results show good possibilities for co-digestionof sewage sludge and microalgae. Further investigations are needed to find optimal conditions for biogas production.

  • 34.
    Thorin, Eva
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Olsson, Jesper
    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.
    Co-digestion of sewage sludge and microalgae: Biogas production investigations2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 227, p. 64-72Article in journal (Refereed)
    Abstract [en]

    In municipal wastewater treatment plants (WWTPs), algae could be utilised for cleaning the water and, at thesame time, produce a biomass that can be used for energy. Through anaerobic digestion, microalgae can contributeto biogas production when co-digested with sewage sludge. In this paper, previous published results onthe co-digestion of sewage sludge and microalgae are summarised and reviewed, and any remaining knowledgegaps are identified. The batch tests currently documented in literature mostly concern digestion under mesophilicconditions, and studies investigating thermophilic conditions are less common. The average biochemicalmethane potential (BMP) for 29 different mixtures co-digested under mesophilic conditions is 317 ± 101 N cm3CH4 gVS−1 while the result for 12 different mixtures investigated under thermophilic conditions is a BMP of318 ± 60 N cm3 CH4 gVS−1. An evaluation of the heat required for increasing the temperature from mesophilicto thermophilic conditions shows that increased methane production under thermophilic conditions can beenough to create a positive energy balance. For a full-scale WWTP, using thermophilic digestion on sludge, or acombination of sludge and microalgae could therefore be of interest. This is dependent on the demands onsanitation of the sludge and the possibilities for heat recovery.Most of the mesophilic investigations indicate a synergetic effect for co-digestion, with enhancements of up toalmost 70%. However, the results are uncertain since the standard deviations for some of the BMP tests are in thesame order of magnitude as the identified enhancement. Neither of the presented publications provide an understandingof the basic mechanisms that led to higher or lower BMP when microalgae were mixed with wastewatersludge. We, therefore, call for care to be taken when assuming any effects related to the specification ofsubstrates. Microalgae and wastewater sludge have several similarities, and the specific results of BMP in themixtures relate more to the specifics of the respective materials than the materials themselves.Investigations into semi-continuous processes of co-digestion of microalgae and sludge are scarce. The yieldsfor three co-digestion studies show high variation, with an average of 293 ± 112 N cm3 gVSin−1. The availableresults show strong potential for co-digestion of sewage sludge and microalgae. Further investigations are requiredto identify optimal conditions for biogas production, and analysis of microalgae implementation onwastewater treatment at a system level is also needed to identify the total mass balance of substrate and nutrientrecovery.

  • 35.
    Thorin, Eva
    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.
    Lindmark, Johan
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Ahrens, Torsten
    Ostfalia University of Applied Science, Wolfenbüttel, Germany.
    DRY DIGESTION PILOT TESTS USING RESIDUAL MUNICIPAL WASTE AS SUBSTRATE2015In: Sardinia 2015 / [ed] Raffaello Cossu et al, Padova: CISA publisher , 2015Conference paper (Refereed)
    Abstract [en]

    A pilot plug-flow dry digestion process was tested for production of biogas from the fine fraction of the residual municipal solid waste after source sorting of the organic fraction of the waste. The residual waste is complex, containing a mix of hard and soft plastic, paper, metal, glass, and a varying amount of organic material. The utilization as a substrate for biogas production is therefore challenging. The purpose of the pilot tests was to determine if it is technically feasible to produce biogas from this waste. The plant was operated under thermophilic conditions for almost three months. In parallel also a garage fermentation batch pilot plant was tested with the same substrate. The results from the tests are promising concerning the biogas production even if there are indications that the process in the plug-flow reactor was operated in so called inhibited steady state at the higher loading rates.

  • 36.
    Törnwall, Elin
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Pettersson, Hanna
    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.
    Post-treatment of biogas digestate – An evaluation of ammonium recovery, energy use and sanitation2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 957-963Article in journal (Refereed)
    Abstract [en]

    The utilization of digestate from anaerobic digestion (AD) processes offers the possibility to recycle nutrient from organic wastematerials back to the food chain. However, digestates are characterized by a high water content resulting in high storagecapacities and transportation costs. Various organic wastes such as organic municipal solid waste (oMSW) require sanitation withat least one hour hydraulic retention time (HRT) at 70°C to inactivate pathogens for the safe release of the material.Consequently, the sanitation process is one of the largest energy consumers in the whole AD process chain. In this study, a posttreatmentof the biogas digestate was evaluated regarding the potential for energy savings and nutrient recovery via nitrogenstripping in comparison to the conventional pre-sanitation of the organic waste. With increasing HRT (one to three hours) andaeration flow (0.0-5.3 L air per L digestate and minute) more condensate and ammonia was removed from the digestate. The totalammonia removal from the digestate after one and three hours with the highest aeration flow rate reached 42% and 80%,respectively. However, energy requirement for aeration exceeded energy savings from the lower volume for sanitation after thedigestion substantially. On a system level, a positive energy balance could still be achieved by taking energy savings from thereplacement of mineral fertilizer (36 GJ per ton NH4) into account. Moreover, the digestate as fertilizer could be applied in amore demand-oriented way by adding ammonium sulphate obtained by the ammonia stripping during the post-treatment.

  • 37.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campillo, Javier
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Technology assessment of the two most relevant aspects for improving urban energy efficiency identified in six mid-sized European cities from case studies in Sweden2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 94, p. 808-818Article in journal (Refereed)
    Abstract [en]

    The increasing population living in cities is leading to higher resource utilization, which strains the cities’ability to focus on sustainability. Adoption of different technologies can transform cities into ‘‘smartcities” that utilize energy in a more efficiently.This paper presents results from a technology assessment tool developed together with six mid-sizedEuropean cities. The main areas of focus have been evaluated based on the cities’ priorities: transportation(both public and private) and consumers’ perspectives on the use of smart electricity meters. The useof electric vehicles in Sweden, and a techno-economic evaluation of biogas-derived biomethane and electricityuse in public transportation have been analyzed. The main conclusions show an overall higher efficiencyfor biogas-derived electricity use in electric buses; a need for higher consumer engagementthrough more detailed information provision for both increasing EV market penetration and electricitysavings; and a need to establish detailed technology assessments for successful technology adoption incities.

  • 38.
    Vassileva, Iana
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Thygesen, Richard
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campillo, Javier
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Schwede, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    From Goals to Action: The Efforts for Increasing Energy Efficiency and Integration of Renewable Sources in Eskilstuna, Sweden2015In: Resources, E-ISSN 2079-9276, Vol. 4, no 3, p. 548-565Article in journal (Refereed)
    Abstract [en]

    Cities’ energy usage accounts for two thirds of global primary energy consumption. Energy efficiency in urban areas is, therefore, one of the most important topics to consider when dealing with urban sustainability. This paper evaluates the goals for increasing energy efficiency and use of renewable energy sources in the areas of transportation, buildings and consumers’ awareness, as stated in the Climate action plan, for the municipality of Eskilstuna, Sweden. The efforts of the municipality to successfully reach their energy efficiency goals, are described in this paper including future perspectives. The results show that although the municipality counts with the advantage of owning and working together with the local housing company and energy provider, in order to reach the established goals, additional strategies need to be considered. For an increased use of renewable energy sources, analysis of rooftops suitable for photovoltaic (PV) installation should be carried out as well as the integration of goals for self-consumption. In the transport field, the city needs to prepare for large-scale electric vehicle (EV) market penetration and to consider different bike or car sharing options. Finally, more specific awareness campaigns are needed to engage the citizens in reducing their energy consumption and living a more sustainable life.

  • 39.
    Wang, B
    et al.
    Mälardalen University. Tianjin Univ Commerce, Key Lab Refrigerat Technol Tianjin, Tianjin, Peoples R China..
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin Univ Commerce, Key Lab Refrigerat Technol Tianjin, Tianjin, Peoples R China..
    Yan, Jinying
    KTH Royal Inst Technol, Chem Engn, Stockholm, Sweden.;Vattenfall AB, R&D, Stockholm, Sweden..
    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.
    Zhu, Kai
    Tianjin Univ Commerce, Key Lab Refrigerat Technol Tianjin, Tianjin, Peoples R China..
    Modelling the Quench Tower in Flue Gas Cleaning of a Waste Fueled Power Plant2018In: JOINT INTERNATIONAL CONFERENCE ON ENERGY, ECOLOGY AND ENVIRONMENT ICEEE 2018 AND ELECTRIC AND INTELLIGENT VEHICLES ICEIV 2018, DESTECH PUBLICATIONS, INC , 2018Conference paper (Refereed)
    Abstract [en]

    To control the emission of pollutants in the flue gas, a separated flue gas quench was added after flue gas desulfurization and before flue gas condensation. A mathematic model was developed to simulate the heat and mass transfer in the flue gas quench. The model was validated through the comparison with measured data. Based on this model, the impacts of inlet flue gas condition and injected recycling water flow rate on the water consumption of the quench and the temperature of exit flue gas (FG) were studied. The results show that the temperature of exit FG and water consumption increased with the increase of flow rate and moisture content of FG. The temperature of exit FG increased and the water consumption decreased with the increase of droplet water diameter. The temperature of exit FG decreased and the water consumption increased with the increase of water flow rate. In order to cooled and humidified the flue gas sufficiently, the droplet diameter should be limited to 1.2 mm and the water to FG flow rate ratio (L/G) higher than 2.

  • 40.
    Wang, Bin
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin Univ Commerce, Key Lab Refrigerat Technol Tianjin, Peoples R China..
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Tianjin Univ Commerce, Key Lab Refrigerat Technol Tianjin, Peoples R China..
    Yan, Jinying
    KTH Royal Inst Technol, Stockholm, Sweden..
    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.
    Zhu, Kai
    Tianjin Univ Commerce, Key Lab Refrigerat Technol Tianjin, Peoples R China..
    Modelling the Quench Tower in Flue Gas Cleaning of a Waste Fueled Power Plant2018In: JOINT INTERNATIONAL CONFERENCE ON ENERGY, ECOLOGY AND ENVIRONMENT ICEEE 2018 AND ELECTRIC AND INTELLIGENT VEHICLES ICEIV 2018, DESTECH PUBLICATIONS, INC , 2018Conference paper (Refereed)
    Abstract [en]

    To control the emission of pollutants in the flue gas, a separated flue gas quench was added after flue gas desulfurization and before flue gas condensation. A mathematic model was developed to simulate the heat and mass transfer in the flue gas quench. The model was validated through the comparison with measured data. Based on this model, the impacts of inlet flue gas condition and injected recycling water flow rate on the water consumption of the quench and the temperature of exit flue gas (FG) were studied. The results show that the temperature of exit FG and water consumption increased with the increase of flow rate and moisture content of FG. The temperature of exit FG increased and the water consumption decreased with the increase of droplet water diameter. The temperature of exit FG decreased and the water consumption increased with the increase of water flow rate. In order to cooled and humidified the flue gas sufficiently, the droplet diameter should be limited to 1.2 mm and the water to FG flow rate ratio (L/G) higher than 2.

1 - 40 of 40
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