Interpreting the synergistic effect in combined ultrasonication-ozonation sewage sludge pre-treatment
The sequential combination of ultrasonication and ozonation as sewage sludge treatment prior to anaerobic digestion was investigated. Synergistic volatile suspended solids (VSS) solubilization was observed when low energy ultrasonication (<12 kJ g−1 TS) was followed by ozonation. 0.048 g O3 g−1 T...
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Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
2015
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Online Access: | https://hdl.handle.net/10356/104317 http://hdl.handle.net/10220/36086 |
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Institution: | Nanyang Technological University |
Language: | English |
Summary: | The sequential combination of ultrasonication and ozonation as sewage sludge treatment prior to anaerobic digestion was investigated. Synergistic volatile suspended solids (VSS) solubilization was observed when low energy ultrasonication (<12 kJ g−1 TS) was followed by ozonation. 0.048 g O3 g−1 TS ozonation induced the maximum VSS solubilization of 41.3% when the sludge was pre-ultrasonicated at 9 kJ g−1 TS; while, the same ozone dosage applied without prior ultrasonication only induced 21.1% VSS solubilization. High molecular weight (MW) components (MW > 500 kDa) were found to be the main solubilization products when sludge was only ozonated. However, solubilization products by ozone were mainly in the form of low MW components (MW < 27 kDa) when sludge was pre-ultrasonicated. The high MW products generated by ultrasound were effectively degraded in the subsequent ozonation. Anaerobic biodegradability increased by 34.7% when ultrasonication (9 kJ g−1 TS) and ozonation (0.036 g O3 g−1 TS) were combined sequentially. The maximum methane production rate increased from 3.53 to 4.32, 4.21 and 4.54 mL CH4 d−1 after ultrasonication, ozonation and ultrasonication–ozonation pre-treatments, respectively. |
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