Adsorption and Ion Exchange

Water is treated with adsorption systems by adding a component to the water supply, such as activated carbon or alumina. Contaminants are attracted to adsorbents by chemical and physical processes that lead them to’stick’ to their surfaces, where they may be disposed of later.

The most common adsorbent is activated carbon, which is comparable to regular charcoal but much more porous. When temporary quality issues emerge, powdered activated carbon is frequently employed; it may easily be added to the water and dumped with the waste sludge. Activated carbon granules are frequently stacked in a bed through which source water is slowly circulated or percolated.

The activated alumina treatment is used to attract and remove pollutants with negatively charged ions, such as arsenic and fluoride. This solution, however, can be costly and may need extensive system upkeep. Additionally, prior to the adsorption column, the water may require pH correction, and a substantial aluminum residue is a typical issue. Regeneration necessitates the use of both acids and bases.

Ion exchange is a technique that involves exchanging charged inorganic pollutants such as arsenic, chromium, nitrate, radium, uranium, and excess fluoride for innocuous charged ions on a resin’s surface. It is most effective with particle-free water and may be adjusted to meet any treatment facility size. The most common applications of ion exchange are to eliminate hardness (cation resin) or nitrate (anion resin). Salt water can be used to renew it in both cases. The use of ion exchange to remove radionuclides is hindered by the fact that these elements build in the resin and are present in large concentrations in the regenerant, making operations extremely difficult.

Ion exchange is commonly favored for eliminating inorganic soluble compounds, whereas activated carbon is favoured for removing organic pollutants.