Recycling activated sludge by hydrodynamic seperator (HDS) to enable high MLSS bioreactor to process high influent flow and/or high strength wastewater

A wastewater treatment plant that employs an activated sludge process and a method of operating the same is described. Wastewater influent is provided to a bioreactor configured to perform activated sludge processing to develop mixed liquor suspended solids (MLSS). The MLSS is passed from the bioreactor to a hydrodynamic separator (HDS) system, where separation operations are performed on the MLSS. The separation operations generate a low concentration MLSS stream and a high concentration MLSS stream. The low concentration MLSS stream is passed from the hydrodynamic separator system via a first output to a clarifier, and the high concentration wastewater stream is passed via a second output back to the bioreactor. The clarifier performs clarification operations on the cleaned wastewater stream and then outputs an effluent flow.