Florida Wastewater Practice Test

A waste treatment pond that is aerobic in the upper portion while the bottom layer is anaerobic is referred to as what?

1. Aerobic pond

2. Facultative pond

3. Combined lagoon

4. Anaerobic lagoon

The correct answer is: Facultative pond

A waste treatment pond that exhibits aerobic conditions in the upper layers while maintaining anaerobic conditions in the bottom layer is referred to as a facultative pond. This type of pond is designed to promote both aerobic and anaerobic processes, taking advantage of the natural stratification of temperature and oxygen levels. In a facultative pond, the upper layer, which is exposed to sunlight, supports aerobic microorganisms that use sunlight for photosynthesis and consume organic matter, thereby producing oxygen. This oxygen supports the aerobic decomposition of waste. Meanwhile, the lower layer, which is isolated from sunlight and oxygen, allows anaerobic bacteria to thrive, breaking down waste in the absence of oxygen. This dual functionality makes facultative ponds particularly effective for treating wastewater as they cater to various microbial processes that can occur simultaneously, enhancing overall treatment efficiency. The contrast with other options is significant, as aerobic ponds are solely aerobic and anaerobic lagoons operate purely under anaerobic conditions without the layered approach that facultative ponds utilize.