What role does the disinfection step play in wastewater treatment?

The disinfection step in wastewater treatment is crucial because it is specifically designed to eliminate pathogens, which are disease-causing microorganisms such as bacteria, viruses, and protozoa. This step is essential for protecting public health, especially when treated water is to be discharged into natural water bodies or reused for irrigation or other purposes. By effectively reducing the number of harmful microorganisms, disinfection ensures that the treated wastewater meets regulatory standards and is safe for the environment and human contact.

The other options do not accurately reflect the purpose of disinfection. Improving water color is more related to other treatment processes, like clarification and filtration. The enhancement of algae growth is not a goal of disinfection; in fact, excessive algae can indicate nutrient overload or poor water quality management. The removal of heavy inorganic materials typically occurs in earlier stages of treatment, such as sedimentation and filtration processes, rather than during disinfection.