1. Physico-chemical treatment of urban wastewater

Physical-chemical water treatment encompasses a number of techniques, such as mixing and aeration, and clarification by decantation. The most widespread method is coagulation-flocculation.

This technique involves adding coagulants to the water, which have the ability to group suspended particles into large aggregates. This facilitates their subsequent removal. The usual methods for separating these aggregates, whether coagulated or flocculated, include filtration, settling at the bottom of the basin (by the action of gravity) or aeroflotation, which involves sending jets of air to bring the particles to the surface of the water.

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