Mesophilic and Thermophilic Digestion of Thickened Waste Activated Sludge: A Comparative Study

Abstract:

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This paper presents an experimental study over 204 days on anaerobic degradation of thickened waste activated sludge (TWAS) from a municipal wastewater treatment plant (WWTP). The experiments were conducted under thermophilic (55°C) and mesophilic (35°C) condition, respectively, by using the semi-continuous flow completely mixed reactors. The influent total solids (TS), hydraulic retention time (HRT) and chemical oxygen demand (COD) loading levels were around 4%, 30 days and 1.67 kg-CODCr•m-3•d-1 , respectively. During the opration period, the thermophilic anaerobic digestion process (TADP) and the mesophilic anaerobic digestion process (MADP) were stable and well-functioned without ammonia inhibition. Particulate organic matters reduction of TADP was superior to that of MADP. This result implies that TADP has higher sludge reduction efficiency than MADP. According to the simulated chemical formula of TWAS, C5.85H9.75O3.96N, and the stoichiometric equation, the methane content and the ammonia yield in the anaerobic process could be calculated, which were consistent with the experimental results. The methane yield of TADP was a little higher than that of MADP. The statistical mean values of methane content for TADP and MADP were 60.97% and 62.38%, respectively.According to paired t-test, there was a significant difference in methane content between TADP and MADP(α=0.01, n=62). Compared with the mesophilic digested sludge, the dewaterability of thermophilic digested sludge was lower.

Info:

Periodical:

Advanced Materials Research (Volumes 113-116)

Edited by:

Zhenyu Du and X.B Sun

Pages:

450-458

DOI:

10.4028/www.scientific.net/AMR.113-116.450

Citation:

Y. Z. Chi et al., "Mesophilic and Thermophilic Digestion of Thickened Waste Activated Sludge: A Comparative Study", Advanced Materials Research, Vols. 113-116, pp. 450-458, 2010

Online since:

June 2010

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Price:

$35.00

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