How does lime aid in the removal of heavy metals from wastewater?

Lime aids in the removal of heavy metals from wastewater primarily by forming insoluble compounds. When lime is introduced into wastewater, it reacts with heavy metals to create metal hydroxides, which are typically insoluble. This process effectively immobilizes the heavy metals, allowing them to precipitate out of the solution as solids. The precipitation is a key mechanism in removing these contaminants from the water, as it facilitates their subsequent removal through sedimentation or filtration.

The formation of insoluble compounds is advantageous in wastewater treatment because it reduces the concentration of heavy metals in the water, which can be harmful to aquatic life and human health. By converting soluble heavy metal ions into solid forms, lime treatment not only lowers the potential for toxicity but also makes it easier to handle and dispose of the resultant sludge.

In contrast, other methods mentioned do not effectively contribute to the removal of heavy metals in the same way. For instance, volatilization typically describes a process where substances turn into vapor, which is not relevant for removing heavy metals from wastewater. While enhancing microbial activity can be beneficial for degrading organic pollutants, it does not specifically target heavy metals. Similarly, increasing solubility would have the opposite effect, making it more difficult to remove heavy metals since dissolved forms are more readily available