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Waste Manag

Title:		"High rate mesophilic, thermophilic, and temperature phased anaerobic digestion of waste activated sludge: a pilot scale study"
Author(s):		Bolzonella D; Cavinato C; Fatone F; Pavan P; Cecchi F;
Address:		"University of Verona, Department of Biotechnology, Strada Le Grazie, 15, 37134 Verona, Italy. david.bolzonella@univr.it"
Journal Title:		Waste Manag
Year:		2012
Volume:		20120204
Issue:		6
Page Number:		1196 - 1201
DOI:		10.1016/j.wasman.2012.01.006
ISSN/ISBN:		1879-2456 (Electronic) 0956-053X (Linking)
Abstract:		"The paper reports the findings of a two-year pilot scale experimental trial for the mesophilic (35 degrees C), thermophilic (55 degrees C) and temperature phased (65+55 degrees 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(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(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(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(3)/kgVS(fed) at 35, 55, and 65+55 degrees C, respectively. The extreme thermophilic reactor working at 65 degrees C showed a high hydrolytic capability and a specific yield of 0.33 g COD (soluble) per gVS(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"
Keywords:		"Acetic Acid/chemistry Anaerobiosis Biological Oxygen Demand Analysis Durapatite/chemistry Fatty Acids, Volatile/chemistry Nitrogen Phosphorus Pilot Projects Propionates/chemistry *Sewage Temperature Waste Management/*methods;"
Notes:		"MedlineBolzonella, David Cavinato, Cristina Fatone, Francesco Pavan, Paolo Cecchi, Franco eng Research Support, Non-U.S. Gov't 2012/02/07 Waste Manag. 2012 Jun; 32(6):1196-201. doi: 10.1016/j.wasman.2012.01.006. Epub 2012 Feb 4"