Particle monitoring techniques for water treatment applications

A simple optical technique based on fluctuations in light transmitted through flowing suspensions has proved useful in two distinct water treatment applications. The first of these is the monitoring and control of coagulation/flocculation processes, where information on optimum coagulant dosages as well as on the dynamics of floc formation can be derived. The method is suitable for a very wide range of particle concentrations, up to levels found in highly turbid river waters. The second application is as a very sensitive monitor of particles in filtered water. Such monitoring can help to ensure the effective removal of pathogens such as Cryptosporidium from drinking water. Brief accounts of these techniques are given, together with some examples of their use.