Method for operating a wastewater-lifting system

A wastewater-lifting system, comprising:

• a bulky material-collecting tank to receive wastewater laden with bulky materials, which are materials in the wastewater that are retained by at least one separating screen, and having the at least one separating screen arranged in the interior of the bulky material-collecting tank configured to retain the bulky material and allow flow of pre-cleaned wastewater separated from the bulky material out of the bulky material-collecting tank;
• a pump for lifting the waste water, connected on one side to the bulky material-collecting tank via a connecting line and on an opposite side to a liquid-collecting tank;
• a bypass line arranged between the connecting line and the liquid-collecting tank, the bypass line connecting to the connecting line between the bulky material-collecting tank and the pump;
• and
• a pivoting flap that is disposed within a flap connector comprising a three-way bolted t-junction defined by opposite ends of the connecting line and an end of the bypass line,
• wherein the wastewater-lifting system is configured such that
• during intake of the wastewater, the pre-cleaned wastewater from the bulky material-collecting tank passes into the liquid-collecting tank via one or both of the pump and the bypass line, and the pivoting flap closes the connecting line at a location between the bypass line and the pump in a direction of the pump except for a flushing cross section configured to allow flushing flow around the pivoting flap toward the pump and opens the bypass line,
• during a pumping process, the pre-cleaned wastewater being withdrawn from the liquid-collecting tank by the pump, opening the connecting line in a direction from the pump to the bulky material-collecting tank and closes the bypass line, wherein
• the flushing cross section is at least in part formed by a bulged portion that is defined by an outward curvature in a wall of the connecting line adjacent to the pivoting flap, the outward curvature being located adjacent to a free end of the pivoting flap, and
• the flushing cross section is established as an annular space or annular cross section, such that in a closed state of the pivoting flap, the pivoting flap is spaced apart from an inner wall of the flap connector.