Phosphate Chemical Use for Sequestration, Scale Inhibition, and Corrosion Control
Christian Lytle, Marc Edwards
Abstract
Water utilities commonly dose phosphates to potable water to (1) reduce aesthetic problems by sequestration, (2) inhibit calcium carbonate scale formation via threshold inhibition, and (3) reduce corrosion of lead or copper plumbing materials by forming protective pipe scales. Despite widespread use and increasing importance of phosphates, significant gaps in fundamental understanding still exist. This is partly due to the proprietary nature of some phosphate chemicals, causing experimental data and acquired knowledge for public water supplies to be considered trade secrets. Here, we summarize the current state of the science, provide operational guidance, and identify knowledge gaps regarding the use of ortho- and polyphosphates. The goal is to empower water scientists to improve phosphate chemical performance and to avoid unintended adverse consequences.