Which type of substances is corrosive and may interfere with biological treatment?

The correct choice highlights that acids and alkalies are types of substances classified as corrosive, which can significantly affect both the infrastructure of wastewater treatment facilities and the biological treatment processes.

Acids and alkalies can alter the pH levels of wastewater. Many biological treatment processes, particularly those involving microorganisms, thrive within specific pH ranges. If the pH falls outside this optimal range—either too acidic or too alkaline—it can inhibit the activity of these microorganisms and disrupt the entire treatment process.

Additionally, corrosive substances can lead to the deterioration of equipment and piping in treatment facilities, which can result in increased maintenance costs and potential system failures. By destabilizing the ecosystem of the biological treatment process, they can lead to lower treatment efficiencies, higher levels of discharged pollutants, and various operational challenges.

While the other substances mentioned can also cause problems in wastewater treatment, their impacts differ. Organic toxicants can indeed disrupt biological treatment but are not necessarily corrosive. Cyanide is highly toxic and can severely affect biological systems, but it is not classified as corrosive in the same manner. Heavy metals can also interfere with biological processes, primarily by being toxic to microorganisms, but they do not possess the corrosive properties that acids and alkalis do. Therefore, recognizing