Abstract: Apparatus for positioning a module containing at least one ultraviolet lamp relative to a passageway in which fluid to be treated flows including a base member fixed to stable structure associated with the passageway and a suspender connected to the base member. The suspender includes a rotatably-mounted latch having a module-engaging portion sized and shaped to engage a module latch receiver associated with the module, a spring associated with the latch and adapted to urge rotation of the module-engaging portion toward and into engagement with the module latch receiver and a rotatably-mounted latch cover positioned adjacent the latch.

Abstract: Modules for use in forming rigid filter beds by laying a plurality of the modules upon a planar base comprise a bottom grid unit to the top of which is fixed a rigid, porous layer. The grid unit has several intersecting series of strip elements with structured portions to promote drainage of liquid through and away from the porous layer. The grid unit may also include portions to insure interlocking of the top porous layer thereto.

Abstract: Improved open gravity backwash filters have a filter chamber containing a particulate filter bed with drainage space beneath the bed and an effluent channel into which filtered effluent from the drainage space flows at a limited rate during the filter mode of operation. The effluent channel has an outflow weir at a height above the top of the filter bed. There is an influent channel in which the influent liquid level is above the top of the filter bed, a gullet with a floor below the top of the filter bed to receive influent from the influent channel and a waste effluent channel with a floor below the level of the top of the filter bed. During the filtering mode, influent is siphoned from the influent channel into the gullet from where it flows to and through the filter bed.

Abstract: Modules for use in forming rigid filter beds by laying a plurality of the modules side-by-side upon a flat base are in the form of porous, planar elements having a continuous, polygonal upper surface, a continuous lower surface approximately coterminous to the upper surface, and sides normal to said surfaces of substantially equal depth much shorter than their length, such elements comprising laminated layers, each layer being formed of particulate material of substantially uniform size rigidly fixed together in a matrix of cured binder, the particles of the layers being substantially different in size than the particles of the adjacent layers, the top surface being flat and the bottom surface being channelled. In preferred forms, the modules' surfaces are square, there are only a top layer and a bottom layer, the top layer is much thinner than the bottom layer and the particles in the top layer are appreciably smaller than the bottom layer particles.