Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon Impeller
The appropriate mixing system and approach to effective management can provide favorable conditions for the highly sensitive microbial community, which can ensure process stability and efficiency in an anaerobic digester. In this study, the effect of mixing intensity on biogas production in a lab-sc...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-11-01
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| Series: | Fermentation |
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| Online Access: | https://www.mdpi.com/2311-5637/7/4/251 |
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| author | Buta Singh Kornél L. Kovács Zoltán Bagi József Nyári Gábor L. Szepesi Máté Petrik Zoltán Siménfalvi Zoltán Szamosi |
| author_facet | Buta Singh Kornél L. Kovács Zoltán Bagi József Nyári Gábor L. Szepesi Máté Petrik Zoltán Siménfalvi Zoltán Szamosi |
| author_sort | Buta Singh |
| collection | DOAJ |
| description | The appropriate mixing system and approach to effective management can provide favorable conditions for the highly sensitive microbial community, which can ensure process stability and efficiency in an anaerobic digester. In this study, the effect of mixing intensity on biogas production in a lab-scale anaerobic digester has been investigated experimentally and via modeling. Considering high mixing efficiency and unique feature of producing axial flow, helical ribbon (HR) impeller is used for mixing the slurry in this experiment under various conditions. Three parallel digesters were analyzed under identical operating conditions for comparative study and high accuracy. Effects of different mixing speeds (10, 30, and 67 rpm for 5 min h<sup>−1</sup>) on biogas production rate were determined in 5-L lab-scale digesters. The results demonstrated 15–18% higher biogas production at higher mixing speed (67 rpm) as compared to 10 rpm and 30 rpm and the results proved statistically significant (<i>p</i> < 0.05). Biogas production at 10, 30, and 67 rpm were 45.6, 48.6, and 52.5 L, respectively. Higher VFA concentrations (7.67 g L<sup>−1</sup>) were recorded at lower mixing intensity but there was no significant difference in pH and ammonia at different speeds whereas the better mixing efficiency at higher speeds was also the main reason for increase in biogas production. Furthermore, model simulation calculations revealed the reduction of dead zones and better homogeneous mixing at higher mixing speeds. Reduction of dead zones from 18% at 10 rpm to 2% at 67 rpm was observed, which can be the major factor in significant difference in biogas production rates at various mixing intensities. Optimization of digester and impeller geometry should be a prime focus to scale-up digesters and to optimize mixing in full-scale digesters. |
| first_indexed | 2024-03-10T04:10:13Z |
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| id | doaj.art-735c9c7cbbfe4f84baad015414c6cd9c |
| institution | Directory Open Access Journal |
| issn | 2311-5637 |
| language | English |
| last_indexed | 2024-03-10T04:10:13Z |
| publishDate | 2021-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Fermentation |
| spelling | doaj.art-735c9c7cbbfe4f84baad015414c6cd9c2023-11-23T08:13:02ZengMDPI AGFermentation2311-56372021-11-017425110.3390/fermentation7040251Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon ImpellerButa Singh0Kornél L. Kovács1Zoltán Bagi2József Nyári3Gábor L. Szepesi4Máté Petrik5Zoltán Siménfalvi6Zoltán Szamosi7Institute of Energy Engineering and Chemical Machinery, University of Miskolc, 3515 Miskolc, HungaryDepartment of Biotechnology, University of Szeged, 6720 Szeged, HungaryDepartment of Biotechnology, University of Szeged, 6720 Szeged, HungaryDepartment of Biotechnology, University of Szeged, 6720 Szeged, HungaryInstitute of Energy Engineering and Chemical Machinery, University of Miskolc, 3515 Miskolc, HungaryInstitute of Energy Engineering and Chemical Machinery, University of Miskolc, 3515 Miskolc, HungaryInstitute of Energy Engineering and Chemical Machinery, University of Miskolc, 3515 Miskolc, HungaryInstitute of Energy Engineering and Chemical Machinery, University of Miskolc, 3515 Miskolc, HungaryThe appropriate mixing system and approach to effective management can provide favorable conditions for the highly sensitive microbial community, which can ensure process stability and efficiency in an anaerobic digester. In this study, the effect of mixing intensity on biogas production in a lab-scale anaerobic digester has been investigated experimentally and via modeling. Considering high mixing efficiency and unique feature of producing axial flow, helical ribbon (HR) impeller is used for mixing the slurry in this experiment under various conditions. Three parallel digesters were analyzed under identical operating conditions for comparative study and high accuracy. Effects of different mixing speeds (10, 30, and 67 rpm for 5 min h<sup>−1</sup>) on biogas production rate were determined in 5-L lab-scale digesters. The results demonstrated 15–18% higher biogas production at higher mixing speed (67 rpm) as compared to 10 rpm and 30 rpm and the results proved statistically significant (<i>p</i> < 0.05). Biogas production at 10, 30, and 67 rpm were 45.6, 48.6, and 52.5 L, respectively. Higher VFA concentrations (7.67 g L<sup>−1</sup>) were recorded at lower mixing intensity but there was no significant difference in pH and ammonia at different speeds whereas the better mixing efficiency at higher speeds was also the main reason for increase in biogas production. Furthermore, model simulation calculations revealed the reduction of dead zones and better homogeneous mixing at higher mixing speeds. Reduction of dead zones from 18% at 10 rpm to 2% at 67 rpm was observed, which can be the major factor in significant difference in biogas production rates at various mixing intensities. Optimization of digester and impeller geometry should be a prime focus to scale-up digesters and to optimize mixing in full-scale digesters.https://www.mdpi.com/2311-5637/7/4/251anaerobic digestionmethane productionmixing intensityoptimization |
| spellingShingle | Buta Singh Kornél L. Kovács Zoltán Bagi József Nyári Gábor L. Szepesi Máté Petrik Zoltán Siménfalvi Zoltán Szamosi Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon Impeller Fermentation anaerobic digestion methane production mixing intensity optimization |
| title | Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon Impeller |
| title_full | Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon Impeller |
| title_fullStr | Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon Impeller |
| title_full_unstemmed | Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon Impeller |
| title_short | Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helical Ribbon Impeller |
| title_sort | enhancing efficiency of anaerobic digestion by optimization of mixing regimes using helical ribbon impeller |
| topic | anaerobic digestion methane production mixing intensity optimization |
| url | https://www.mdpi.com/2311-5637/7/4/251 |
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