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David T. Chapman
Journal (Water Pollution Control Federation)
Vol. 57, No. 3, Part I (Mar., 1985), pp. 227-234
Stable URL: http://www.jstor.org/stable/25042567
Page Count: 8
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## Abstract

The response of a pilot-scale settler was investigated under transient loading conditions. The overflow rate varied between 24.5 and $40.6\ {\rm m}^{3}/{\rm m}^{2}\cdot {\rm d}$ and the hydraulic residence time between 1.5 and 2.5 hours according to step changes in flow rate. Feed solids concentration was varied and the effluent suspended solids concentration was monitored by a computer-interfaced turbidimeter. Process time constants were estimated from the response curves to determine how quickly the process changed from one level to another: the average was 17 minutes for step increases and 26 minutes for step decreases. The average time constant for response to feed solids concentration was ∼5 hours. The gain varied from 4 to 7 mg/L per g/L change. Variability increased with mean effluent suspended solids. The results demonstrate that clarification is non-linear and adversely affected by sudden changes in flow.

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