This study was undertaken to evaluate the laboratory performance of the anaerobic fluidized bed digesting secondary biological sludge at 35° C with four hydraulic-retention times (HRTs): 1, 2.5, 5, and 10 days. In addition, the effects of both operating temperature (15° C, 25° C and 35° C) and the initial sludge solubilization on the digester performance were also examined. It was found that at 35° C, an adequate degree of sludge digestion was obtainable with an HRT of only 1-2 days if the influent biological sludge was presolubilized by treatment with 17.5 meq/L of sodium hydroxide. If no presolubilization was used, the necessary HRT was increased to 10 days. When the temperature was decreased to 25° C and the sludge was presolubilized, the required HRT was 2.5-3 days. However, as the temperature was further decreased to 15° C, the system was unable to achieve adequate digestion in as long as 10 days, even with presolubilization. It was also observed that the fluidized-bed system was able to accept abrupt increases of loading without a corresponding buildup of excessive organic acids. © ASCE.


Civil, Architectural and Environmental Engineering

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Article - Journal

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Publication Date

01 Jan 1989