The study reported in this paper considered the results of pilot-scale experiments on single and 2-phase anaerobic digestion of waste activated sludge at high rate. Both single and 2-phase digesters were conducted at the same conditions of organic loading and retention time. The 2-phase anaerobic system showed clear increases in terms of organic matter removal and biogas production compared to the single stage system. Particularly, the volatile solids removal rose from 34% in the single stage system to 38% in the 2-phase system. Hence, the global specific biogas production increased 32%, moving from 0.21 to 0.31 m(3)/kgTVS.d respectively for the single and 2-phase systems. The 2-phase system produced 15% more energy than the single stage system. Furthermore, the heat produced in a CHP unit satisfied all heat requirements insuring more than the complete energetic sustainability of the process. Finally, both single and 2-phase digestates showed to meet requirements established for sludge reuse in agriculture regarding pathogens, metals and organic contaminants. A preliminary economic analysis showed the possibility to pay back the investment for the implementation of a second anaerobic reactor in 3 years because of both the increased biogas production and reduced quantity of excess sludge to be disposed of. (c) 2015 Elsevier Ltd. All rights reserved.

Performance and energy aspects of single and two phase thermophilic anaerobic digestion of waste activated sludge

Gottardo, Marco;Pavan, Paolo;
2016

Abstract

The study reported in this paper considered the results of pilot-scale experiments on single and 2-phase anaerobic digestion of waste activated sludge at high rate. Both single and 2-phase digesters were conducted at the same conditions of organic loading and retention time. The 2-phase anaerobic system showed clear increases in terms of organic matter removal and biogas production compared to the single stage system. Particularly, the volatile solids removal rose from 34% in the single stage system to 38% in the 2-phase system. Hence, the global specific biogas production increased 32%, moving from 0.21 to 0.31 m(3)/kgTVS.d respectively for the single and 2-phase systems. The 2-phase system produced 15% more energy than the single stage system. Furthermore, the heat produced in a CHP unit satisfied all heat requirements insuring more than the complete energetic sustainability of the process. Finally, both single and 2-phase digestates showed to meet requirements established for sludge reuse in agriculture regarding pathogens, metals and organic contaminants. A preliminary economic analysis showed the possibility to pay back the investment for the implementation of a second anaerobic reactor in 3 years because of both the increased biogas production and reduced quantity of excess sludge to be disposed of. (c) 2015 Elsevier Ltd. All rights reserved.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10278/3703905
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