Which of the following is a common laboratory test conducted on wastewater?

Pathogen detection assays are a common laboratory test conducted on wastewater because they provide crucial information about the presence of harmful microorganisms. These assays are essential for ensuring public health and environmental safety. Wastewater can contain a variety of pathogens, including bacteria, viruses, and parasites, that can pose significant risks if not adequately treated before the water is released into the environment or reused. Testing for pathogens helps operators assess the efficacy of treatment processes and determine whether additional measures are needed to eliminate these contaminants.

The other options are not typical tests performed on wastewater itself. Radioactivity detection is more relevant in contexts where radioactive materials might be present, such as in certain industrial or medical facilities. Soil permeability tests are used in geotechnical engineering to understand how water flows through soil, which is not a focus of wastewater testing. Thermal conductivity tests are often employed in assessing the thermal properties of materials, not in evaluating wastewater. Therefore, while these tests have their applications, they do not directly relate to the routine analysis of wastewater, making pathogen detection assays the correct choice in this context.