METHOD AND DEVICE FOR PURIFYING WASTE WATER, IN PARTICULAR FOR FULLY BIOLOGICAL DOMESTIC SEWAGE TREATMENT SYSTEMS

The invention concerns a device (1) for purifying waste water (3) in which the waste water (3) is optionally fed via a denitrification chamber (5) to an activation chamber (6) arranged downstream of the latter. From the activation chamber (6), the waste water (3) is further conveyed, via a sludge outlet (10), to a secondary settling chamber (7) which is connected, via an outlet (16), to a WC-flush water reservoir (17) and/or a main outfall (18). An aeration system (8), for example an agitator (9), is disposed in the activation chamber (6). Disposed in a front face area of the secondary settling chamber (7), which area faces the base (12) of a reservoir (4), is a sludge channel (11) or a connection pipe (43) provided with a protective screen (13). Said screen is preferably formed by parts of the sludge channel (11) or of the connection pipe and overlaps a cross-sectional area of the sludge channel (11) or of the connection pipe (43) in a plane (15) perpendicular to the longitudinal axis (14) of the reservoir (4) whilst maintaining the outlet (10) for the sludge.