High rate mesophilic, thermophilic, and temperature phased anaerobic digestion of waste activated sludge: A pilot scale study

Journal Article · Fri Jun 15 00:00:00 EDT 2012 · Waste Management

DOI:https://doi.org/10.1016/j.wasman.2012.01.006· OSTI ID:21612984

Bolzonella, David ^[1]; Cavinato, Cristina ^[2]; Fatone, Francesco ^[1]; Pavan, Paolo ^[2]; Cecchi, Franco ^[1]

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1. University of Verona, Department of Biotechnology, Strada Le Grazie, 15, 37134 Verona (Italy)
2. University of Venice, Department of Environmental Sciences, Computer Science and Statistics, Dorsoduro 2137, 30123 Venice (Italy)

Highlights: Black-Right-Pointing-Pointer High temperatures were tested in single and two-stage anaerobic digestion of waste activated sludge. Black-Right-Pointing-Pointer The increased temperature demonstrated the possibility of improving typical yields of the conventional mesophilic process. Black-Right-Pointing-Pointer The temperature phased anaerobic digestion process (65 + 55 Degree-Sign C) showed the best performances with yields of 0.49 m{sup 3}/kgVS{sub fed}. Black-Right-Pointing-Pointer Ammonia and phosphate released from solids destruction determined the precipitation of struvite in the reactor. - Abstract: The paper reports the findings of a two-year pilot scale experimental trial for the mesophilic (35 Degree-Sign C), thermophilic (55 Degree-Sign C) and temperature phased (65 + 55 Degree-Sign C) anaerobic digestion of waste activated sludge. During the mesophilic and thermophilic runs, the reactor operated at an organic loading rate of 2.2 kgVS/m{sup 3}d and a hydraulic retention time of 20 days. In the temperature phased run, the first reactor operated at an organic loading rate of 15 kgVS/m{sup 3}d and a hydraulic retention time of 2 days while the second reactor operated at an organic loading rate of 2.2 kgVS/m{sup 3}d and a hydraulic retention time of 18 days (20 days for the whole temperature phased system). The performance of the reactor improved with increases in temperature. The COD removal increased from 35% in mesophilic conditions, to 45% in thermophilic conditions, and 55% in the two stage temperature phased system. As a consequence, the specific biogas production increased from 0.33 to 0.45 and to 0.49 m{sup 3}/kgVS{sub fed} at 35, 55, and 65 + 55 Degree-Sign C, respectively. The extreme thermophilic reactor working at 65 Degree-Sign C showed a high hydrolytic capability and a specific yield of 0.33 gCOD (soluble) per gVS{sub fed}. The effluent of the extreme thermophilic reactor showed an average concentration of soluble COD and volatile fatty acids of 20 and 9 g/l, respectively. Acetic and propionic acids were the main compounds found in the acids mixture. Because of the improved digestion efficiency, organic nitrogen and phosphorus were solubilised in the bulk. Their concentration, however, did not increase as expected because of the formation of salts of hydroxyapatite and struvite inside the reactor.

• OSTI ID: 21612984
• Journal Information: Waste Management, Vol. 32, Issue 6; Other Information: DOI: 10.1016/j.wasman.2012.01.006; PII: S0956-053X(12)00020-7; Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
AMMONIA
ANAEROBIC DIGESTION
APATITES
EFFICIENCY
MESOPHILIC CONDITIONS
METHANE
NITROGEN
PHOSPHATES
PHOSPHORUS
PRECIPITATION
PROPIONIC ACID
SALTS
SLUDGES
SOLIDS
TEMPERATURE RANGE 0400-1000 K
THERMOPHILIC CONDITIONS
VOLATILITY
WASTES
YIELDS
ALKANES
BIOCONVERSION
CARBOXYLIC ACIDS
DIGESTION
ELEMENTS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
MINERALS
MONOCARBOXYLIC ACIDS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHATE MINERALS
PHOSPHORUS COMPOUNDS
SEPARATION PROCESSES
TEMPERATURE RANGE