Removal of metal and metalloid ions in water

Metal ions and metalloids are found in drinking water, domestic and industrial wastewater and runoff. A large number of elements are released into the aquatic environment through leaching from transport routes, as well as from soils which naturally contain metals and metalloids in various forms. It should be noted, however, that these inorganic compounds are necessary to life as trace elements, and their impact on the environment may be low. Nonetheless, as the poison is in the dose, the same cannot be said of massive discharges of high concentrations of metal ions or metalloids into surface waters. Their elimination is necessary from the point of view of human health, or to combat their direct impact on the receiving environment: soil, water, air, and therefore on flora and fauna. The recommendations of the World Health Organization (WHO), legislation via European directives and French decrees are particularly abundant in regulating concentrations in wastewater discharges, but also in water intended for human consumption. These health, environmental and regulatory arguments have led to the implementation of treatments to better control metal and metalloid levels in water. Relying on the physicochemical properties of each species, treatment processes are multiple and combine the use of adjuvants (coagulation, flocculation), adsorbents or ion exchange, oxidants or reducers, as well as membrane barriers, electrolysis and/or the use of plants in phytoremediation.

While this article takes a global approach to the problem of metals and metalloids in water, it also focuses on physicochemical and biological treatment and purification processes.