Certain embodiments include a screen assembly of a vessel, where the screen assembly includes a plurality of fixed elements and a retainer, and the retainer includes a ring, a plurality of wedges disposed about the ring, and a plurality of keyholes at spaced locations about the ring.

Each keyhole includes a bore and a slot extending from the bore into an adjacent wedge of the plurality of wedges, the slots have a width less than the bores, and the retainer may receive the fixed elements through the bores and may be rotated in a relation with the plurality of fixed elements to bring the plurality of fixed elements into simultaneous engagement with the wedges.

In a solid-liquid separation apparatus, which comprises multiple movable members and screws that extend and pass through the movable members without contacting the movable members and which dehydrates sludge while conveying same by means of the rotation of the screws, to apply a wringing action on the sludge and increase sludge dehydration efficiency. (Solution) A first movable unit 41 is configured by linking multiple movable members 4A and 4B as a unit with a linking rod 44, a second movable unit 41A is configured by linking multiple other movable members 4C and 4D as a unit with a linking rod 44A, and the movable members 4A and 4B of the first movable unit 41 and the movable members 4C and 4D of the second movable unit 41A are reciprocated with a phase difference.

In a solid-liquid separation apparatus, which comprises multiple movable members and screws that extend and pass through the movable members without contacting the movable members and which dehydrates sludge while conveying same by means of the rotation of the screws, to apply a wringing action on the sludge and increase sludge dehydration efficiency. (Solution) A first movable unit 41 is configured by linking multiple movable members 4A and 4B as a unit with a linking rod 44, a second movable unit 41A is configured by linking multiple other movable members 4C and 4D as a unit with a linking rod 44A, and the movable members 4A and 4B of the first movable unit 41 and the movable members 4C and 4D of the second movable unit 41A are reciprocated with a phase difference.

A liquid filter has an outer housing and a filter drum. The outer housing has an outer wall and a pair of end walls that are positioned on opposed sides of the outer wall. The outer housing has an inlet and at least one outlet. The filter drum has a side wall, a first end wall and a second end wall. The first end wall and the second end wall are positioned on opposed sides of the side wall. The filter drum is secured within the outer housing. The filter drum has a t least one filter fastened in at least one of the first end wall and the second end wall to allow liquid to flow from an exterior of the filter drum to an interior of the filter drum. The inlet is positioned on the outer housing such that liquid is fed tangentially in relation to the filter drum through the inlet to create a centrifugal force within the outer housing causing solid particles to be forced towards the outer wall of the outer housing. The filter drum has at least one outlet pipe in fluid communication with the interior of the filter drum and the at least one outlet of the outer housing through which filtered liquid may pass.

A liquid filter has an outer housing and a filter drum. The outer housing has an outer wall and a pair of end walls that are positioned on opposed sides of the outer wall. The outer housing has an inlet and at least one outlet. The filter drum has a side wall, a first end wall and a second end wall. The first end wall and the second end wall are positioned on opposed sides of the side wall. The filter drum is secured within the outer housing. The filter drum has a t least one filter fastened in at least one of the first end wall and the second end wall to allow liquid to flow from an exterior of the filter drum to an interior of the filter drum. The inlet is positioned on the outer housing such that liquid is fed tangentially in relation to the filter drum through the inlet to create a centrifugal force within the outer housing causing solid particles to be forced towards the outer wall of the outer housing. The filter drum has at least one outlet pipe in fluid communication with the interior of the filter drum and the at least one outlet of the outer housing through which filtered liquid may pass.

A method for treating wastewater in a wastewater treatment plant includes passing the wastewater passes through a rake system and, thereafter, a sand trap to separate from the wastewater, solids having different particle sizes. A screening device screens the wastewater emerging from the sand trap to yield a primary sludge that fails to pass through the screening device and a suspension passing through the screening device. The suspension is fed to at least one further treatment stage, and the primary sludge is thickened with the aid of at least one thickener. The thickened primary sludge is fed to one or several further treatment stages. Moreover, a wastewater treatment plant for treating wastewater is described.

A method for treating wastewater in a wastewater treatment plant includes passing the wastewater passes through a rake system and, thereafter, a sand trap to separate from the wastewater, solids having different particle sizes. A screening device screens the wastewater emerging from the sand trap to yield a primary sludge that fails to pass through the screening device and a suspension passing through the screening device. The suspension is fed to at least one further treatment stage, and the primary sludge is thickened with the aid of at least one thickener. The thickened primary sludge is fed to one or several further treatment stages. Moreover, a wastewater treatment plant for treating wastewater is described.

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.

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.

A discharge method and a discharge device for a cleaning device (2) for filters (5, 6), includes a supply line (26) which can be connected to a collection region (23) for removed filter residue (9) of the cleaning device (2). The discharge device (3) has a controllable metering device (4) which adjoins the supply line (26) and which blocks the supply line (26) and receives removed filter residue (9) from the supply line (26) in portions (35) in a meterable manner and discharges same at a different location. For this purpose, the metering device (4) has a metering element (28) which can be moved in a controllable manner, in particular a rotatably and/or movably arranged metering element. The filter residue (9) can be removed from the filter (5, 6) via a backflushing process or in a mechanical manner using a scraper or the like.