What is the primary purpose of using sodium thiosulfate in wastewater sampling?

The primary purpose of using sodium thiosulfate in wastewater sampling is to neutralize chlorine. In many wastewater treatment processes, chlorine is used as a disinfectant to kill harmful bacteria and pathogens. However, when collecting samples for analysis, the residual chlorine can interfere with tests that measure the presence of microbiological organisms, as it may kill them and lead to inaccurate results.

By adding sodium thiosulfate to the sample, the chlorine is effectively neutralized, allowing for a more accurate assessment of microbial content and other characteristics of the wastewater. This step is essential for obtaining reliable results in microbiological testing and ensuring that the data represents the actual conditions of the wastewater being tested.