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http://dx.doi.org/10.3741/JKWRA.2014.47.5.483

Economic Design of Activated Sludge System at the Optimum Sludge Concentration  

Lee, Byung Joon (School of Construction and Environmental Engineering, Kyungpook National University)
Choi, Yun Young (School of Construction and Environmental Engineering, Kyungpook National University)
Publication Information
Journal of Korea Water Resources Association / v.47, no.5, 2014 , pp. 483-490 More about this Journal
Abstract
The design procedures for a biological reactor and a secondary settling tank (SST) of an activated sludge system are based on the steady state design method (Ekama et al., 1986; WRC, 1984) and the 1-D flux theory design method (Ekama et al., 1997), respectively. This study combined both of the design procedures, to determine the optimum sludge concentration in the reactor and the best design with the lowest cost. The best design of the reactor volume and the SST diameter at the optimum sludge concentration were specified with varying wastewater and sludge characteristics, temperature, sludge retention time (SRT) and peak flow rate. The effects of the influent wastewater characteristics, such as substrate concentration and unbiodegradable particulate fraction, were found to be considerable, but the effect of unbiodegradable soluble fraction was to be negligible. The effects of sludge settling characteristics, were also significant. SRT, as an operating parameter, was found to be an important factor for determining the optimum sludge concentration. However, the effect of temperature was found to be small. Furthermore, for designing a large scale wastewater treatment plant, the number of reactors or SSTs could be estimated, by dividing the total reactor volume or SST area. The new combined design procedure, proposed in this research, will be able to allow engineers to provide the best design of an activated sludge system with the lowest cost.
Keywords
activated sludge; biological reactor; secondary settling tank; optimum design;
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