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Very long sludge retention time (SRT) is a key factor in anaerobic digestion of sewage sludge. The effect of the SRT on the performance of the anaerobic digestion of a mixture of primary and activated sludge was investigated. Twelve lab scale (8 liters) digesters were operated at four different SRT (5, 10, 20 and 40 days) in triplicate. The performance of the digesters was evaluated through measuring gas production and composition, volatile suspended solids (VSS), chemical oxygen demand (COD), and effluent quality. COD removal efficiencies ranged from 33.2 to 45.5 %. VSS removals ranging from 35.8 to 49.0 % were observed. The solid disintegration was modeled as a first order decay in a continuous stirred tank reactor (CSTR). The calculated biodegradable fraction of the VSS was 0.51, while the first order reaction rate constant was 0.44 d−1.

Document Type: Research Article


Publication date: 2002-01-01

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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