Process and system for purification of waste water

摘要

A process and a system for the purification of waste water in several successive stages includes a first stage for anaerobic treatment of the waste water, a second stage for aerobic treatment of the waste water, a third stage for clarification and sedimentation of the waste water with a sludge return, and an arrangement for controlling the residence time of the waste water in the anaerobic stage by varying the volume of the anaerobic stage.