6. Emerging trends and processes

While the need to remove metal ions and metalloids from water is well established in the interests of human health, the environment and regulatory compliance, there is still room for improvement in treatment processes, and a number of trends can be identified.

• Precipitation by pH variation is limited by the solubility of the hydroxides formed in water. To improve this process, coupling with another technique, such as coagulation-flocculation with metal salts and/or polymeric additives, or adsorption or biosorption, may be of interest. Moreover, precipitation is a process with limited selectivity.

• Ion exchange remains a technique for the massive and more or less selective removal of high concentrations of ions from water for specific industrial uses.

• For certain metalloids,...