Tennessee Wastewater Operator Practice Exam

What is the primary difference between an OUR and a SOUR test?

1. OUR measures only oxygen levels

2. SOUR corrects for sludge concentration

3. THEY use different microbial species

4. OUR measures volatile solids

The correct answer is: SOUR corrects for sludge concentration

The primary difference between an OUR (Oxygen Uptake Rate) test and a SOUR (Specific Oxygen Uptake Rate) test lies in the aspect of sludge concentration that is taken into account. The SOUR test specifically corrects for the concentration of biomass (sludge) in the system, allowing for a more accurate assessment of the metabolic activity of microorganisms relative to the amount of biomass present. This means that the SOUR gives a measure of how efficiently the microorganisms consume oxygen on a per-unit-biomass basis, which is crucial for evaluating the performance of biological treatment processes. In contrast, the OUR test simply measures the overall rate of oxygen uptake without normalizing it to the biomass concentration. This can make it difficult to gauge the specific performance of the microbial population because variations in sludge concentration can skew the results. By correcting for biomass, the SOUR provides a more precise picture of the system's biological activity, making it a valuable tool for operators to assess and optimize treatment processes.