What time frame is specified for averaging BOD and suspended solids in secondary treatment?

The correct answer is the specified time frame for averaging Biochemical Oxygen Demand (BOD) and suspended solids in secondary treatment is 30 days. This period is significant because it aligns with the regulatory requirements set by the Texas Commission on Environmental Quality (TCEQ) and other environmental regulations.

Averaging these parameters over 30 days ensures that the data reflects the treatment system's performance over a reasonable period, accounting for variations that can occur day-to-day due to factors such as inflow changes, operational adjustments, and variations in influent characteristics. Monitoring over a 30-day time frame helps provide a stable average that better represents the treatment plant's ability to consistently remove organic matter and suspended particles.

This standard is also important for compliance reporting and helps ensure that facilities are meeting their operational permits and maintaining environmental protection standards. By averaging the data over 30 days, it allows operators and regulators to assess the effectiveness of the treatment processes and identify any prolonged issues that may need to be addressed.