Which substance is commonly used to oxidize metals in wastewater treatment?

The substance commonly used to oxidize metals in wastewater treatment is chlorine. Chlorine is a powerful oxidizing agent that can effectively remove various metals from wastewater through oxidation-reduction reactions. When chlorine is introduced to water, it reacts with specific metals, converting them into less toxic forms or precipitating them out of solution, which facilitates their removal from the water.

This process is particularly important in wastewater treatment because it helps in the overall reduction of pollutants and the enhancement of water quality before it is discharged into the environment or reused. Chlorine's effectiveness and versatility make it a standard choice in the treatment of wastewater containing heavy metals and other contaminants.

In contrast, hydrochloric acid is primarily used for pH adjustment and to dissolve metals, not for their oxidation. Boric acid has applications in controlling pH and as an antiseptic, but it does not serve as an oxidizer for metals. Sodium bicarbonate is mainly used for pH correction in wastewater treatment, further distinguishing it from the oxidizing role of chlorine.