Interactions of Silica Particles in Drinking Water Treatment Processes

EPA Grant Number: U915331
Title: Interactions of Silica Particles in Drinking Water Treatment Processes
Investigators: Clarkson, Christina L.
Institution: Virginia Polytechnic Institute and State University
EPA Project Officer: Lee, Sonja
Project Period: August 1, 1998 through August 1, 2000
Project Amount: $55,314
RFA: STAR Graduate Fellowships (1998) RFA Text |  Recipients Lists
Research Category: Fellowship - Environmental Engineering , Engineering and Environmental Chemistry , Academic Fellowships


The objective of this research project is to understand how the presence of silica (sand) particles impacts drinking water treatment processes. This project will seek answers to the following questions:

1. How do silica particles affect the coagulation, flocculation, and sedimentation processes? How do the observed effects compare with the effects when monosilicic acid or polysilicates are present?

2. Mechanistically, how do silica particles interact with coagulants during water treatment?

3. In what types of source waters is the addition of silica beneficial?


Silica interactions will be investigated by tracking particle behavior in the presence and absence of sand. Particles (combinations of natural turbidity, silica, and coagulant) will be characterized by filtration through a 0.45 micrometer pore size filter, a zeta potentiometer, and a submicron particle sizer. The goal is to understand the effects of silica on relative rates of chemical nucleation, precipitation, particle agglomeration, and sedimentation. As part of that evaluation, water quality effects, rate of chemical addition, and order of chemical addition will be investigated. It is anticipated that the results will provide improved fundamental understanding, which can be applied to further optimizing the relatively new sand-ballasted process.

Supplemental Keywords:

fellowship, sorption, silica, coagulation, flocculation, sedimentation, monosilicic acid, polysilicates, drinking water treatment, source water, zeta potentiometer, submicron particle sizer, chemical nucleation, precipitation, particle agglomeration, silica, silica particles., RFA, Scientific Discipline, Water, Wastewater, Civil/Environmental Engineering, Drinking Water, Engineering, Engineering, Chemistry, & Physics, Environmental Engineering, coagulation, microsand enhanced coagulation, drinking water regulations, alternative technology, treatment, water treatment, other - risk management, TOC removal

Progress and Final Reports:

  • 1999
  • Final