According to US EPA standards, what should the pH level of secondary treatment effluent be?

The pH level of secondary treatment effluent is an important parameter for ensuring the effluent meets environmental standards and is safe for discharge into receiving waters. The US EPA specifies that the pH of secondary treatment effluent should typically be within the range of 6 to 9.

This range is considered optimal because it minimizes harmful effects on aquatic life and is conducive for various biological processes involved in wastewater treatment. A pH level below 6 could indicate acidity that may harm organisms in receiving waters, while a pH above 9 could indicate alkalinity that might also be detrimental.

The specified pH range of 6 to 9 ensures that the treated wastewater remains neutral to slightly alkaline, which is ideal for maintaining the health of aquatic ecosystems and allows for the effective functioning of biological treatment processes.