Final answer:
The article discusses substrate concentration in a reactor and its normal distribution.
Step-by-step explanation:
The article is discussing the substrate concentration of influent to a reactor. The values given for the mean and standard deviation are μ = 0.50 and σ = 0.09, respectively. This suggests that the substrate concentration follows a normal distribution. For example, if we want to find the probability of the substrate concentration being less than a certain value, we can use the standard normal distribution table.