Degradation of Drinking Water Treatment Plant Infrastructure from Enhanced Coagulation

Abstract

The new Enhanced Coagulation Rule requires that drinking water utilities improve the removal of natural organic matter from their water. One common method of doing so is to “enhance” the performance of existing coagulation processes by increasing the coagulant dose, changing the coagulant type, or lowering the coagulation pH. There is growing concern that these treatment changes might cause degradation of cement and metallic components of drinking water treatment plant infrastructure. In a survey of enhanced coagulation impacts at 275 water utilities, 24% have reportedly already seen at least some infrastructure degradation. A comprehensive literature review highlights the potential causes for the degradation observed by utilities, and recommendations are provided to guide utilities seeking to minimize degradation and repair existing damage.