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ÇALLI, BARIŞ

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BARIŞ

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Author: AKGÜL, DENİZ × Has files: true ×

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    PublicationOpen Access
    Enhancing biogas production from chicken manure through vacuum stripping of digestate
    (2023-01-01) AKGÜL, DENİZ; ÇALLI, BARIŞ; Sengur O., AKGÜL D., Bayrakdar A., ÇALLI B.
    The vacuum stripping’s combined ammonia removal and disintegration effect on chicken manure digestate was evaluated for the first time at different pH values (8.5, 9.5, and 10.5) and temperatures (30, 50, and 70 °C). In this way, the potential increase in biogas production by recirculating the vacuum-stripped digestate to the anaerobic digester was determined. Experimental results showed that increasing pH and temperature significantly increase TAN removal, but pH is more effective. A significant portion of the ammonia was removed in the first 30 min. Therefore, a second set of stripping tests was performed for 30 min and at 70 °C and pH 10.5. After 30-min tests, a biomethane potential (BMP) assay was performed using the vacuum-stripped digestate to determine how vacuum stripping affects biomethane production. Despite having the lowest disintegration efficiency, the highest biomethane potential (56.2 ± 29.7 mL CH4/gVS) was obtained with the digestate, which was subjected to vacuum stripping at 70 ℃ without pH adjustment, and 48.7% more methane was produced than the control set. The lower residual biomethane potential in vacuum-stripped digestate at pH 9.5 and 10.5 was attributed to Na+ inhibition resulting from high NaOH consumption for pH adjustment. Graphical abstract: [Figure not available: see fulltext.]
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    PublicationOpen Access
    In situ methane enrichment with vacuum application to produce biogas with higher methane content
    (2024-01-01) AKGÜL, DENİZ; ÇALLI, BARIŞ; Sengur O., AKGÜL D., ÇALLI B.
    Sludge produced in sewage treatment plants is an important source of organic matter to be used in anaerobic digestion to produce energy-rich biogas. The biogas produced in anaerobic digesters has a critical impact on achieving carbon neutrality and improving energy self-sufficiency. After effective upgrading, biogas can be converted into biomethane with an increased CH4 content, resulting in a higher volumetric energy value. Upgrading biogas to biomethane thus not only improves its energy content but also broadens its potential uses. In this study, it was aimed at enrich CH4 by removing dissolved CO2 from the digestate using a vacuum, leveraging the solubility differences of gases in liquid. In this context, two digesters (R-T and R–C) were operated for 194 days, and the effect of vacuum on in-situ methane enrichment was investigated. The vacuum was only applied to the test reactor (R-T), and the CH4 percentage was increased from 63 to 87, 80, and 75% in the vacuum exposure time intervals of 30, 10, and 5 min, respectively. Extended durations were not tested, as the rate of enrichment decreased sharply after 30 min. The maximum energy requirement of a vacuum application was estimated at 0.124 kWh/ m3 methane. Conversely, vacuum application did not cause any deterioration in biogas production, and the methane yields were similar in both reactors. Keywords Biogas upgrading, Carbon dioxide, Digestate, Biomethane, Waste activated sludge, Negative pressure