An apparatus for separating out and removing screenings from wastewater includes a screening device having a screen surface through which the wastewater flows during operation of the screening device and screenings carried along in the wastewater are at least intermittently retained. The apparatus includes a sensor and a controller. The sensor monitors the screenings in the area upstream from the screen surface and/or in the area of the screen surface. The controller outputs a message when the screenings have one or several properties which have been defined and have been recognized by the sensor. In addition, a method for operating the apparatus and a system including the apparatus are provided.