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Batch rolling-bed dryer applicability for drying biomass prior to torrefaction
(Elsevier, 2025) Szufa, Szymon; Ünyay, Hilal; Pakowski, Zdzislaw; Piersa, Piotr; Siczek, Krzysztof; Kabaciński, Mirosław; Sobek, Szymon; Moj, Kevin; Likozar, Blaž; Kostyniuk, Andrii; Junga, Robert; Faculty of Process and Environmental Engineering. Lodz University of Technology. Szymon Szufa, Hilal Unyay, Zdzislaw Pakowski, Piotr Piersa.; Department of Vehicles and Fundamentals of Machine Design. Lodz University of Technology. Krzysztof Siczek.; Department of Thermal Engineering and Industrial Facilities. Opole University of Technology. Kabaciński, Mirosław and Junga, Robert.; Department of Heating, Ventilation, and Dust Removal Technology. Silesian University of Technology. Sobek, Szymon.; Faculty of Mechanical Engineering. Opole University of Technology. Moj, Kevin.; Department of Catalysis and Chemical Reaction Engineering. National Institute of Chemistry. Likozar, Blaž and Kostyniuk, Andrii.
This study investigates the suitability of a pilot-scale batch rolling-bed dryer for drying pine wood chips intended for torrefaction. The batch rolling bed dryer emerges as an ideal solution for further processes like torrefaction, offering a compact design and a wide range of operational parameters. Compared to rotary dryers, it occupies less volume, providing greater efficiency. Additionally, its adjustable drying airflow and compatibility with various biomass forms and particle sizes enhance its versatility. The volumetric evaporation rate was found 13.9 kg/m3 per hour for the total dryer volume and 78.8 kg/m3 for the bed volume. Mechanical tests demonstrate satisfactory operation, with potential for further optimization through impeller blade design improvements. The study also presents a simple model using the CDC modeling approach, successfully describing drying curves in most experiments, albeit with some limitations in temperature curve simulations. Overall, the rolling bed dryer proves to be a convenient solution for drying wood chips as a pretreatment for steam torrefaction, offering ease of operation and promising potential for application in continuous torrefaction lines.
Harnessing Switchgrass for Sustainable Energy: Bioethanol Production Processes and Pretreatment Technologies
(MDPI Open Access Journals, 2024) Ünyay, Hilal; Perendeci, Nuriye, Altınay ; Piersa, Piotr; Szufa, Szymon; Skwarczynska-Wojsa, Agata; Faculty of Process and Environmental Engineering, Lodz University of Technology. Unyay, Hilal and Piersa, Piotr and Szufa, Szymon.; Department of Environmental Engineering. Akdeniz University. Perendeci, Nuriye, Altınay.; Department of Water Purification and Protection. Rzeszow University of Technology. Skwarczynska-Wojsa, Agata.
This paper investigates bioethanol production from switchgrass, focusing on enhancement of efficiency through various pretreatment methods and comparing two bioethanol production processes: simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF). Physical, chemical, and biological pretreatment processes are applied to enhance the breakdown of switchgrass’s lignocellulosic structure. Effects of pretreatments, enzymatic hydrolysis, and fermentation on ethanol yield are discussed in detail. The comparative analysis reveals that SSF yields higher ethanol outputs within shorter times by integrating hydrolysis and fermentation into a single process. In contrast, SHF offers more control by separating these stages. The comparative analysis highlights that SSF achieves higher ethanol yields more efficiently, although it might restrict SHF’s operational flexibility. This study aims to provide a comprehensive overview of the current pretreatments, hydrolysis methods, and fermentation processes in bioethanol production from switchgrass, offering insights into their scalability, economic viability, and potential environmental benefits. The findings are expected to contribute to the ongoing discussions and developments in renewable bioenergy solutions, supporting advancing more sustainable and efficient bioethanol production techniques.
Reduction of spruce phytotoxicity by superheated steam torrefaction and its use in stimulating the growth of ecological bio‑products: Lemna minor L
(Springer Nature, 2025) Szufa, Szymon; Ünyay, Hilal; Piersa, Piotr; Kędzierska‑Sar, Aleksandra; Romanowska‑Duda, Zdzislawa; Likozar, Blaz; Faculty of Process and Environmental Engineering. Lodz University of Technology. Szymon Szufa, Hilal Unyay, Piotr Piersa & Aleksandra Kędzierska-Sar.; Faculty of Biology and Environmental Protection. University of Lodz. Zdzislawa Romanowska-Duda.; Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry. Szymon Szufa & Blaz Likozar.
The use of biochar in agriculture is associated with the concepts of "carbon sink" and "carbon negative," which will constitute additional income for farms in the near future and may provide them with a key role in the fight against global warming. The existing model in the Scandinavian countries is one of the first to combine biochar with carbon dioxide biosequestration. Fertilizers with excessive nutrient content, salinity issues, impurities, or irregular pH levels can induce phytotoxicity, damaging plant health and growth. Torrefied woody biomass can work as a bulking agent, carbon carrier, or as an mendment for composting materials containing high amounts of water and/or nitrogen contents. Superheated steam torrefaction as a valorization process increases the amount of pores in which minerals can be stored and the plant will grow faster and bigger by using these pores agglomerated minerals. The torrefaction process was conducted using the DynTHERM TG Rubotherm high-temperature and high-pressure thermogravimetric analysis apparatus under conditions of superheated steam flow. Various residence times (10, 20, and 40 min) and torrefaction temperatures (250, 275, and 300 °C) were explored to assess their efficacy in reducing the phytotoxicity of torrefied spruce. To confirm this assumption, a toxicity test with Lemna minor L. was carried out according to Radić et al. (2011) and extended to the determination of chlorophyll index and chlorophyll fluorescence to assess the physiological status of the plants after treatment with different doses of spruce wood biocarbon. Research indicates that biochar positively impacts soil quality and plants. Thanks to its unique properties, biochar provides nutrients, enhancing fertilization efficiency [1]. Biochar, after concentrating and adsorbing the nutrients from the wastewater, can be used as a soil amendment or fertilizer. Biochar blended with organic residues full of nutrients is more effective in improving soil properties and crop yields than the exclusive application of pure biochar or other fertilizers. Traditional chemical fertilizers have drawbacks, such as rapid nutrient leaching, severe environmental pollution, and high costs. Therefore, biochar is gaining increasing recognition worldwide.
Valorisation potential of black tea processing wastes for bioactive compounds recovery and renewable energy production
(Elsevier, 2025) Ünyay, Hilal; Altay, Hatice Özmen; Perendeci, N. Altınay; Szufa, Szymon; Özdemir, Feramuz; Angelidaki, İrini; Faculty of Process and Environmental Engineering. Lodz University of Technology. Ünyay, Hilal and Szufa, Szymon.; Akdeniz University, Engineering Faculty. Food Engineering Department. Altay, Hatice Özmen.; Akdeniz University, Engineering Faculty. Environmental Engineering Department. Perendeci, N. Altınay and Ünyay, Hilal.; Department of Chemical and Biochemical Engineering, Technical University of Denmark. Perendeci, N. Altınay and Angelidaki, İrini.; Akdeniz University, Engineering Faculty. Food Engineering Department. Özdemir, Feramuz.; torrefaction
Tea processing wastes, rich in carbohydrates—primarily cellulose and hemicellulose—and bioactive compounds such as polyphenols and caffeine, represent a valuable biomass resource that can be utilised for antioxidant extraction and energy recovery. Tea factories are assumed to produce uniform waste due to blending and accumulating residues in shared storage; however, four distinct waste types arise at different processing stages, each showcasing unique traits. Waste samples were taken directly from two different factories that produce black tea with Çaykur (nonpressed orthodox + rotorvane + pressed orthodox) and Rotorvane + CTC production methods belonging to the Turkish Tea Board, Türkiye, within three shooting periods and four black tea processing stages. Tea processing waste samples were evaluated from the point of resource recovery as bioactive compounds and energy production. Significant variations were found in total phenolic content (4.75–8.65 gGAE/100 gDM), gallic acid (0.47–0.61 %), and caffeine (1.33–2.54 %) levels among the tea wastes examined. Tea processing waste from the Çaykur method exhibited higher caffeine content. Methane production from anaerobic digestion ranged from 97.3 to 203.9 mLCH4/gVS. Under torrefaction at 285°C, the higher heating value (HHV) demonstrated a remarkable 43.9 % increase, reaching a peak HHV of 24.36 MJ/kg. Torrefaction yielded impressive energy yields of 82.3 % and 92.1 %. These findings underscore the efficacy of torrefaction at this temperature in boosting the energy content of the biomass while maintaining high energy yield percentages. This study presents the first integrative and multidimensional framework for tea waste valorisation, offering comprehensive insights into its dual-purpose utilisation by concurrently assessing bioactive compounds such as total phenolic content, polyphenolic profile, and caffeine concentration and energy potential through biogas and biochar production across different tea manufacturing techniques, waste stream types, and shooting period.