Course: BFM 203 Water Treatment and Control

Lecture

What are These Particles?

What are These Particles?

Impurities in the water result from land erosion, pickup of minerals caused by the decay of plant material, airborne contaminants, industrial discharges, and animal wastes. Two terms that relate to these particles are "particulate" and "colloids." Particulate refers to a very small solid suspended in water which can vary widely in size, shape, density, and electric charge. Colloids are very small, finely divided solids that remain dispersed in a liquid for a long time due to their small size and electrical charge. These particles are difficult to settle and may contain pathogens (disease-causing microorganisms). The photo to the right (courtesy of the RRCC Water Quality Management Program) illustrates particulate and colliods in water.

Coagulant chemicals are used to bring the particles into a floc that can be settled or filtered more easily. Floc is a very fine mass formed by the aggregation (coagulation) of particulate and colloids through the use of a coagulant.