METHOD AND PUMP UNIT FOR THE EFFECTIVE TREATMENT OF SEWAGE IN A TRANSFER TANK

In performing the method according to the invention the sewage accumulating in the transfer tank is periodically drawn away and is, in given circumstances, stirred in such a manner that the sewage is guided into the pump horizontally or downward at an acute angle to the horizontal, and the periodic pumping is performed such that when the sewage level attains a height of 1-30 cm above the pump intake opening, the electric motor is operated at a reduced sewage throughput and when, in given circumstances, the sewage level intersects the intake opening and/or the pump impeller, the electric motor is operated without sewage throughput for ventilating the sewage advantageously for at least 3 seconds, but expediently for at least 10 seconds. Stirring is performed such that the sewage is, in a vortex coaxial with the rotary axis of the stirrer agitating the sewage, first accelerated toward the stirring element and then guided along the superficies thereof and is eventually ejected in a impulse-like manner. The pump unit (4) proper comprises an electric motor (5) and a pump (6) and is arranged in the transfer tank in such a manner that its rotary axis is horizontal or is oriented at an acute angle to the horizontal and the intake opening (7) of the pump (6) is at the top.