Which of the following is a common source of aluminum in wastewater?

Plating and anodizing are processes that commonly use aluminum, and as a result, they can contribute to aluminum levels in wastewater. In the plating process, metals are coated to enhance their properties, such as corrosion resistance, and aluminum is often utilized for this purpose. Anodizing is an electrochemical process that increases the thickness of the natural oxide layer on the surface of aluminum parts, which also introduces aluminum compounds into wastewater. The chemicals and residues from these industrial practices can easily find their way into wastewater systems, making them significant sources of aluminum contamination.

While raw material extraction can also introduce aluminum into the environment, it typically involves larger scale mining operations, which is not as directly linked to wastewater in everyday scenarios compared to plating and anodizing. Municipal sewage may contain various metals, but it is less focused on direct sources of aluminum compared to plating. Agricultural runoff is more often associated with fertilizers and pesticides rather than metals, making it a less likely source of aluminum contamination. Thus, plating and anodizing stand out as a primary source of aluminum in wastewater systems.