Which common test is used to assess microbial activity in wastewater?

The Biochemical Oxygen Demand (BOD) test is widely recognized as a critical method for assessing microbial activity in wastewater. BOD measures the amount of oxygen that microorganisms will consume while decomposing organic matter in a water sample at a specific temperature over a set period, typically five days. This test provides valuable insights into the level of organic pollution in the water and indicates how effectively microorganisms can break down that organic matter.

In contrast, other tests such as the Chemical Oxygen Demand (COD) test measure the total quantity of oxygen required to chemically oxidize both organic and inorganic substances in the water, which does not specifically account for microbial activity. The Total Suspended Solids (TSS) test quantifies the solid particles suspended in the water but does not provide information regarding the microbial processes or the biological treatment capacity of wastewater. Respirometry, while useful in certain contexts, is a more specialized approach focused on measuring the respiration rate of microorganisms, which indirectly reflects microbial activity but is not as commonly used for general assessments in wastewater treatment as the BOD test.

Thus, the Biochemical Oxygen Demand test stands out as the standard method for gauging microbial activity due to its direct relationship with the biodegradation process.