Journal of Environmental Engineering

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Letterman, R., Hadad, M., and Driscoll, C. (1991). ”Limestone Contactors: Steady‐State

Design Relationships.” J. Environ. Eng.,117(3), 339–358.

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Limestone Contactors: Steady‐State Design Relationships

Article History

Published: 01 May 1991

Publication Data

ISSN (print): 0733-9372

ISSN (online): 1943-7870

Publisher: American Society of Civil Engineers

Raymond D. Letterman, Member, ASCE1; Marwan Hadad

2; and Charles T. Driscoll

3

1Prof., Dept. of Civ. and Envir. Engrg., Syracuse Univ., Syracuse, NY 13244

2Prof., Dept. of Civ. Engrg., An‐Najah Univ., Nablus, West Bank, Israel

3Prof., Dept. of Civ. and Envir. Engrg., Syracuse Univ., Syracuse, NY

Abstract:

Limestone contactors can mitigate corrosion in small water‐supply systems that use

dilute, acidic water. As water is transported through a packed bed of crushed

limestone, CaCO3dissolves and the pH, calcium‐ion concentration, and alkalinity

increase. Operation of a contactor can be effectively modeled by considering the rate of

dissolution and interfacial transport of calcium ions. The steady‐state model developed

and tested in this study relates the depth of limestone required in the contactor to the

desired effluent water chemistry, influent water chemistry, limestone‐particle size and

shape, bed porosity, water temperature, and superficial velocity. The magnitude of the

rate constant that describes the release of calcium ions from the calcite surface varies

with the pH at the particle surface. When this pH is less than about 9.5, the rate constant

for the surface reaction becomes large, and the rate of dissolution tends to be controlled

solely by the transport of calcium ions away from the interface.