What percentage of influent BOD should biological secondary treatment processes ideally remove?

Biological secondary treatment processes are designed to significantly reduce the biochemical oxygen demand (BOD) of influent wastewater. The goal of these processes is to achieve a high level of BOD removal to ensure that the effluent released into the environment meets regulatory standards and does not negatively impact water quality.

Ideally, an effective biological treatment process should aim to remove at least 85% of the influent BOD. At this level of removal, the wastewater can be treated sufficiently to support aquatic life in receiving waters and to comply with environmental regulations. This benchmark is based on the performance of well-operated treatment facilities under optimal conditions.

In contrast, while 75%, 80%, or 90% removals can be targets for specific situations or advanced treatment methods, the established standard for standard secondary biological treatment systems is set at 85%. Achieving this percentage not only enhances the treatment efficiency but also contributes positively to overall water management and quality control efforts in wastewater systems.