After reducing hexavalent chromium, how is trivalent chromium commonly removed?

Trivalent chromium is commonly removed from wastewater through hydroxide precipitation. This process involves increasing the pH of the wastewater, which leads to the formation of insoluble chromium hydroxide compounds. These compounds separate from the liquid phase and can then be easily removed from the water as sludge during subsequent treatment processes. Hydroxide precipitation is particularly effective for trivalent chromium because it tends to stay in a more stable form at elevated pH levels, leading to better removal efficiency.

In contrast, while other methods such as filtration, electrolysis, and activated carbon adsorption can be useful for different contaminants or scenarios, they are not typically the primary methods used for removing trivalent chromium in comparison to hydroxide precipitation. Each of these alternative methods may have limitations regarding efficiency, cost, or appropriate conditions for use in treating chromium specifically.