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Influence of the Oxic-Settling-Anaerobic (OSA) Process on Methane Production by Anaerobic Digestion of Sewage Sludge
The present study evaluated different sludge-reduction mechanisms in the oxic-settling-anaerobic (OSA) process in terms of their effects on methane productivity by anaerobic digestion of sewage sludge. Two different layouts were investigated for the sludge return from an anaerobic side-stream reactor (ASSR) to the anoxic (scheme A) or the aerobic (scheme B) reactor of a pre-denitrification plant. Biochemical methane-potential (BMP) assays performed on the excess sludge revealed that scheme A promoted an overall increase of methane production in the OSA (20 mLCH4 gVSS−1d−1, +19%), although compared with a control CAS plant a significant decrease in the excess sludge production (31%) was obtained. Operating conditions in scheme A caused the occurrence of cell lysis and EPS hydrolysis, thereby increasing the biodegradability of sludge. In contrast, scheme B favoured the occurrence of uncoupling and a maintenance metabolism that did not involve sludge hydrolysis. Consequently, despite a higher reduction of excess sludge (82%), a significant decrease in methane productivity in the OSA (4 mLCH4 gVSS−1d−1, −41%) was observed. Based on the results, implementing the OSA process may allow high levels of methane production by anaerobic digestion to be maintained if specific sludge-reduction mechanisms are triggered in the waterline, also raising the possibility of co-digestion with other feedstocks.
Influence of the Oxic-Settling-Anaerobic (OSA) Process on Methane Production by Anaerobic Digestion of Sewage Sludge
The present study evaluated different sludge-reduction mechanisms in the oxic-settling-anaerobic (OSA) process in terms of their effects on methane productivity by anaerobic digestion of sewage sludge. Two different layouts were investigated for the sludge return from an anaerobic side-stream reactor (ASSR) to the anoxic (scheme A) or the aerobic (scheme B) reactor of a pre-denitrification plant. Biochemical methane-potential (BMP) assays performed on the excess sludge revealed that scheme A promoted an overall increase of methane production in the OSA (20 mLCH4 gVSS−1d−1, +19%), although compared with a control CAS plant a significant decrease in the excess sludge production (31%) was obtained. Operating conditions in scheme A caused the occurrence of cell lysis and EPS hydrolysis, thereby increasing the biodegradability of sludge. In contrast, scheme B favoured the occurrence of uncoupling and a maintenance metabolism that did not involve sludge hydrolysis. Consequently, despite a higher reduction of excess sludge (82%), a significant decrease in methane productivity in the OSA (4 mLCH4 gVSS−1d−1, −41%) was observed. Based on the results, implementing the OSA process may allow high levels of methane production by anaerobic digestion to be maintained if specific sludge-reduction mechanisms are triggered in the waterline, also raising the possibility of co-digestion with other feedstocks.
Influence of the Oxic-Settling-Anaerobic (OSA) Process on Methane Production by Anaerobic Digestion of Sewage Sludge
Santo Fabio Corsino (author) / Daniele Di Trapani (author) / Federica De Marines (author) / Michele Torregrossa (author) / Gaspare Viviani (author)
2023
Article (Journal)
Electronic Resource
Unknown
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The Research Progress on Oxic-Settling-Anaerobic Sludge Reduction Process
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Mechanism on minimization of excess sludge in oxic-settling-anaerobic (OSA) process
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Some effects of anaerobic digestion on sewage sludge
| Engineering Index Backfile | 1949
Some effects of anaerobic digestion on sewage sludge
| Engineering Index Backfile | 1948