Optimization of subcritical water pre-treatment for biogas enhancement on co-digestion of pineapple waste and cow dung using the response surface methodology
•SCW pre-treatment optimization study prior co-digestion was established.•SCW pre-treatment enhances the biogas production in co-digestion process.•The co-digestion for pretreated and untreated material was investigated.•The chemicals and structural properties of PW changed after pre-treatment. The...
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Published in | Waste management (Elmsford) Vol. 150; pp. 98 - 109 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Ltd
01.08.2022
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Subjects | |
Online Access | Get full text |
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Summary: | •SCW pre-treatment optimization study prior co-digestion was established.•SCW pre-treatment enhances the biogas production in co-digestion process.•The co-digestion for pretreated and untreated material was investigated.•The chemicals and structural properties of PW changed after pre-treatment.
The optimal pre-treatment method and conditions depend on the types of lignocellulose present due to the complexity and the variability of biomass chemical structures. This study optimized subcritical water pre-treatment to ensure maximum methane production from pineapple waste prior to anaerobic co-digestion with cow dung using the response surface methodology. A central composite design was achieved with three different factors and one response. A total of 20 pre-treatment runs were performed at different temperatures, reaction times and water to solid ratios suggesting optimum values for subcritical water pre-treatment at 128.52℃ for 5 min with 5.67 to 1 water to solid ratio. Under these conditions, methane yield increased from 59.09 to 85.05 mL CH4/g VS with an increase of 23% biogas yield and 44% methane yield from the untreated. All pre-treatments above 200℃ showed reductions in biogas yield. Compositional analysis showed slight reduction of lignin and increase in α-cellulose content after the pre-treatment. Analysis using Fourier transform infrared spectroscopy and thermogravimetric analysis verified the presence of cellulosic material in pre-treated pineapple waste. Most of the hemicellulose was solubilized in the liquid samples after SCW pre-treatment. The crystallinity index of pineapple waste was reduced from 57.58% (untreated) to 54.29% (pre-treated). Scanning electron microscopy confirmed the structural modification of pre-treated pineapple waste for better microbial attack. Subcritical water pre-treatment is feasible as a promising method to enhance the anaerobic co-digestion process. Further study should be conducted to assess the scale-up of the process from pre-treatment to anaerobic digestion at the pilot plant level. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0956-053X 1879-2456 |
DOI: | 10.1016/j.wasman.2022.06.042 |