How can a toxic waste be discovered in a treatment plant?

A decrease in dissolved oxygen (DO) levels in aerators can be indicative of the presence of toxic waste in a treatment plant. When toxic substances enter the treatment process, they often inhibit the activity of microorganisms that are essential for the biological treatment of wastewater. These microorganisms rely on a certain level of DO to perform their functions effectively. An unexpected increase in aerator DO might not directly signal the presence of toxicity, but rather could suggest changes in the biochemical environment, potentially connected to the introduction of toxic agents.

In contrast, a change in pH levels is indeed significant as it indicates alterations in water chemistry, which may suggest influences from chemical pollutants, but does not directly link to the presence of toxic waste. Similarly, a decrease in water temperature can occur for various reasons unrelated to toxicity, such as seasonal changes or operational adjustments. Excessive foam production may indicate organic loading issues or the presence of surfactants, but again, it doesn't directly confirm toxic waste. The identification of toxic waste requires careful monitoring of the biological activity, which is closely related to DO levels in the aeration process.