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2023

Selle valdkonna püsiv URIhttp://hdl.handle.net/10492/8643

Sirvi

Sirvi 2023 Märksõna "anaerobic digestion" järgi

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  • Pisipilt
    Kirje
    Comparison of different chemical-free pretreatment methods for the production of sugars, ethanol and methane from lignocellulosic biomass
    (Estonian University of Life Sciences, 2023) Sjulander, Nikki; Rooni, Vahur; Rocha-Meneses, Lisandra; Kikas, Timo; Estonian University of Life Sciences. Institute of Forestry and Engineering. Chair of Biosystems Engineering
    Most pretreatment methods for lignocellulosic biomass use strong chemicals, such as sulphuric acid and ammonia, to open up the cellular structure of plant biomass. However, those chemicals are not environmentally friendly and their use leads to safety risks. As a result, different chemical-free pretreatment methods have been developed, which focus on the usage of pressure, high or low temperatures and mild chemicals. Freezing pretreatment and explosive decompression pretreatments, using different operating gases, such as nitrogen and steam, are compared in the context of glucose, ethanol and methane yield in this review. For the methane production, the stillage from bioethanol production is used. The usage of this waste improves the overall valorisation of lignocellulosic biomass. The review also investigates, whether the nitrogen explosive decompression pretreatment is suitable for the treatment of softwoods, hardwoods and herbaceous materials. In the comparison of different chemical-free pretreatment methods, it is concluded that heat and water are the most influential parameters for opening up the lignocellulosic biomass structure. The operating gas and pressure in the pretreatment reactor are less relevant. Steam explosion, nitrogen explosive decompression pretreatment and autohydrolysis pretreatment are the most suitable chemical-free pretreatment methods for lignocellulosic biomass.
  • Pisipilt
    Kirje
    Increased biogas production from lignocellulosic biomass by soaking in water
    (Estonian University of Life Sciences, 2023) Jankovičová, B.; Hutňan, M.; Imreová, Z.; Zakhar, R.
    Due to its large production worldwide, lignocellulosic biomass represents a substrate with great potential to produce biogas. However, this type of biomass is characterized by a complex and solid structure, which is difficult to decompose by anaerobic microorganisms. Applying the correct pre-treatment method can increase its biodegradability. Lignocellulosic substrate was pre-treated by soaking in water for one day at room temperature to increase biogas production and monitoring of long-term operation of laboratory models of anaerobic reactors for anaerobic digestion of such pre-treated maize waste was employed. Monitoring results in two reactors, R1 with biogas produced from a substrate soaked in water for one day and R0 with the production of biogas from a substrate mixed with water just before dosing into the reactor, were compared showing positive effect of the pre-treatment method. This was expressed by higher values of biogas production and higher methane content in biogas from the substrate soaked in water for one day. The achieved specific biogas productions during four different phases of reactor operation in reactor R1 were in the range of 190–335 mL g-1 of VS (volatile solids) and 101–221 mL g-1 of VS in reactor R0. Methane content of biogas during reactor operation was 49.3–55.2% in reactor R1 and 42.5–45.5% in reactor R0. During long-term operation of another reactor, pre-treated maize waste was used as a co-substrate for maize silage, in the ratio of 1:1 based on VS of the substrates proving as a suitable co-substrate for maize silage, as the achieved average value of specific biogas production during reactor operation at OLR (organic loading rate) = 1.75 kg VS m-3 d-1 was 510 mL g-1 of VS and during first 67 days at OLR = 2 kg VS m-3 d-1 it was 454 mL g-1 of VS.