What happens during the log phase of growth according to the notes?

• A. Growth slows
• B. Death occurs first
• C. No growth occurs
• D. The number of cells in the population increases rapidly; can double every 20 minutes

Answer: (D)

During the log phase, microbial cells divide at a nearly constant, rapid rate because nutrients and oxygen are plentiful. This is an exponential growth period where the population increases quickly, often doubling in a short, regular interval—about every 20 minutes for fast-growing organisms under ideal conditions. In wastewater treatment, this means microbes are actively metabolizing organic matter and multiplying rapidly, which drives the treatment process forward. The other descriptions correspond to other phases: growth slows as resources become limited (stationary phase), no growth occurs while cells acclimate (lag phase), or death can begin if conditions are stressful.