Which cleaning method is categorized under mechanical cleaning?

Mechanical cleaning refers to the use of physical action to remove contaminants from a surface, rather than relying on chemical processes. Among the choices provided, brush scrubbing fits this definition because it involves using a brush to physically scrub surfaces, thereby dislodging dirt and debris through friction. This form of cleaning is effective because it allows the operator to apply force directly to the surface, which can be especially useful for tough grime or buildup that other methods may not effectively eliminate.

In contrast, steam cleaning utilizes high-temperature steam to loosen dirt, and while it can have a physical effect, it primarily relies on the properties of steam as a cleaning agent, which aligns more with thermal rather than purely mechanical methods. EDTA cleaning involves a chemical agent that binds to metal ions and removes them through a chemical reaction, which is clearly a chemical cleaning process. Washing with soap also depends on the chemical properties of the soap to emulsify and lift soils away from surfaces, making it another chemical approach.

Thus, brush scrubbing is the only method listed that is purely mechanical in nature, focusing on physical action to clean rather than chemical solutions.