What characterizes a facultative pond?

A facultative pond is characterized by the presence of both aerobic and anaerobic layers. This unique feature occurs because the pond is designed to promote the growth of microorganisms that thrive in varying conditions. In the upper layer, where sunlight penetrates, photosynthetic algae and bacteria engage in aerobic processes, utilizing oxygen produced by photosynthesis and breaking down organic matter. Beneath this upper layer, the conditions become more anaerobic as oxygen is depleted and organic matter continues to decompose, allowing for the activity of different types of microorganisms that thrive in the absence of oxygen.

This stratification of conditions enables the pond to effectively treat wastewater by allowing different microbial communities to work together to break down pollutants efficiently. This characteristic distinguishes facultative ponds from other types of treatment systems that may rely solely on aerobic or anaerobic processes.