Which action is appropriate to take if dissolved oxygen levels are low in a treatment pond?

Increasing aeration is a crucial action to take when dissolved oxygen levels are low in a treatment pond. Aeration promotes the exchange of gases, allowing oxygen from the atmosphere to be dissolved into the water. This is vital for maintaining aerobic conditions, which are essential for the survival of aerobic microorganisms that break down organic matter in the wastewater. The presence of adequate dissolved oxygen is necessary not only for the health of these microorganisms but also for maintaining the overall efficiency of the treatment process, as low oxygen levels can lead to the proliferation of anaerobic conditions, resulting in malodorous by-products and reduced treatment efficacy.

Alternatives such as adding chlorine or sodium hydroxide do not address the oxygen deficiency; in fact, chlorine can potentially harm the very microorganisms needed for effective treatment, while sodium hydroxide primarily affects pH levels but does not contribute to oxygen levels. Reducing inflow might temporarily mitigate the problem, but without addressing the underlying issue of low dissolved oxygen, it won't provide a long-term solution to ensuring a healthy treatment environment. Thus, increasing aeration is the most effective way to elevate dissolved oxygen levels and promote a healthy wastewater treatment process.