New Hypothesis for Secondary Clarifier Performance Under Hydraulically Limited Conditions
Abstract:A new criterion called the effluent upflow velocity (EUV) is proposed as an important parameter affecting secondary clarifier performance under hydraulically limited conditions. Defined as the upflow velocity in the effluent withdrawal zone of a secondary clarifier, the EUV is proposed as having a direct link to clarifier performance in the presence of a wide range of particle size distributions in the effluent withdrawal zone. It is hypothesized that a wide range of particle size distributions in the effluent withdrawal zone of a clarifier could result from one of two factors: poor mixed liquor flocculation characteristics or strong density currents capable of resuspending previously settled floc. Consequently, in the presence of either of these factors, the EUV would likely show the best correlation with clarifier effluent suspended solids, more so than traditional hydraulic criteria such as the surface overflow rate or weir loading rate. Results from clarifier modifications completed at the County Sanitation Districts of Orange County's Wastewater Treatment Plant No. 2 in Huntington Beach, California, are presented in support of this hypothesis.
Document Type: Research Article
Publication date: January 1, 2000
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- Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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