Calibration of a compressive gravity thickening model from a single batch settling curve

• Published in: Water Science & Technology Vol. 30; no. 8; pp. 107 - 116
• Main Authors: Cacossa, K F, Vaccari, DA
• Format: Journal Article Conference Proceeding
• Language: English
• Published: London IWA Publishing 01.01.1994
• Subjects: Calibration; Capacity; Coefficients; Compressive strength; Computer simulation; Concentration gradient; Curve fitting; Dynamic pressure; Gravitation; Gravity; Methods; Optimization; Pressure gradients; Quantitative analysis; Settling; Sludge; Suspended particulate matter; Thickening; Total suspended solids
• DOI: 10.2166/wst.1994.0392
• ISBN: 9780080426297; 0080426298
• ISSN: 0273-1223

A compressive gravity thickening model was calibrated from a single batch settling curve. This model was originally formulated in terms of the total suspended solids concentration, C, the dynamic pressure gradient, partial differential P/ partial differential z, and the gradient corresponding to the compressive yield strength, partial differential sigma sub(y)/ partial differential z. Fitch (1975) demonstrated that the model could be formulated in terms of C and the solids concentration gradient, partial differential C/ partial differential z. Utilizing this formulation the model was calibrated with data generated from elementary quantitative analysis of the steady-state conditions attained in continuous thickening experiments. In this investigation the model was calibrated from a single batch settling curve. This was done using the down-hill simplex optimization method proposed by Nelder and Mead (1965) in a curve-fitting capacity. The optimization routine adjusted the model coefficients in order to reduce the discrepancy between the simulated results of the model and the corresponding experimental batch settling data. When calibrated by this method the model was found to accurately predict experimental continuous thickening behavior observed for the same sludge.