Which chemical is commonly used to raise the pH of wastewater?

The chemical commonly used to raise the pH of wastewater is calcium oxide. This compound is a strong alkaline substance, and when added to water, it reacts to form hydroxide ions, which increase the overall pH of the solution. This adjustment is essential in wastewater treatment processes, particularly when acidic conditions need to be neutralized to meet regulatory standards or to facilitate the effectiveness of biological treatment processes. Raising the pH can help optimize conditions for microbial activity and reduce the corrosive nature of the wastewater.

Other chemicals mentioned in the choices have different uses or effects. Sodium hydroxide is also a strong base and could effectively raise pH, but it is not the most common choice due to its handling and safety concerns. Ammonium sulfate is primarily used as a nitrogen source for bacteria in treatment processes and does not significantly increase pH. Potassium chloride, on the other hand, is neutral in terms of pH and is used mainly for other purposes, such as nutrient addition in some treatment scenarios.