Water treatment before use. Particulate matter

This article only concerns water directly involved in industrial processes through the means available to achieve the required quality objectives when the raw material is natural fresh water, with seawater being subject to specific desalination techniques. In many cases, there are significant similarities with the treatment of drinking water, which is similar to all or part of the treatment of industrial water.

Whether the resource is surface water (river, natural or artificial lake) or groundwater, the raw water it supplies to the user will have all or some of the following undesirable characteristics:

• organoleptic criteria: turbidity, color, taste, smell;

• chemical criteria, corresponding to constituents:

  • are naturally present in water: mineral salts (e.g., hardness, sulfates, chlorides, etc.), iron, manganese, ammonium, fluorides, arsenic, organic matter known as "natural" or MON (particularly humic substances responsible for color), etc.

  • either caused by pollution: anthropogenic macropollutants (carbon, nitrogen, and phosphorus organic matter, nitrates, phosphates), mineral micropollutants (heavy metals, metalloids, oxohalides), or organic micropollutants (pesticides, hydrocarbons, phenols, detergents, per- and polyfluoroalkyl substances or PFAS, drug residues, etc.);

• Biological criteria: these mainly concern pathogenic germs carried by fecal pollution, but also organisms whose natural habitat is water (viruses, protozoa, planktonic microalgae or phytoplankton, microinvertebrates or zooplankton, environmental bacteria).

To eliminate or correct all these unfavorable parameters, water treatment plants have a number of tools at their disposal, which must first be reviewed: coagulation and flocculation reactors; decanters; flotation units; beds of granular materials with filtering, adsorbing, and/or neutralizing effects; adsorption, oxidation, and ion exchange reactors; membrane processes, etc. These tools will be combined in more or less complex processes, depending on the industry in question and the use of the water [G 1 172] and [W 5 510]...