Despite the low pH of bulk water, the photosynthetic activities of aqueous organisms can result in a significant elevation of pH in their surrounding microenvironment and subsequently lead to the formation of calcium carbonate (CaCO3, calcite) in waters that are rich in alkalinity and hardness. In some cases, the organisms can also act as a nucleus. Therefore, CaCO3 clouds (also known as whiting particles) are often seen in water experiencing an algal bloom event. These particles can be difficult to remove by conventional coagulants and filtration, bringing up a significant operational concern for water treatment utilities. Considering a typical positive zeta potential of CaCO3, their removal was specifically evaluated in this study using different charge and molecular size ionic polymers (alone, as a filter aid or as a coagulant aid). The performance was monitored in terms of particle counts, size/volume distributions, and floc morphology. This study provides a useful set of data in assessing the treatment effectiveness of whiting particles.

Removing whiting particles (CaCO3, calcite) from water by different organic and inorganic flocculants

251st National Meeting (2016)

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