Abstract: A filter employing a discrete particle filter medium (3,11), such as graded sand or the like, in which the outlet passage (6) located at the bottom (1, 29,8) of a bed of filter medium is provided in which air can be employed in the backwashing process to agitate the filter medium. The filter has shallow coarser layers (9,10,28) of particulate material beneath the filter medium (11) itself and one set of outlet nozzles (14,19,27) having appropriately dimensional perforations positioned in the coarser or coarsest particle layer (9,28). In addition further finer perforated surfaces (16,23,30) communicate with the bottom of the filter medium (11) itself and the arrangement is such that when air is introduced perparatory to, or during backwashing the air emerges predominantly from the elevated finer perforated surfaces (16,23,30).

Abstract: This invention relates to flocculation apparatus for the purification of liquids, particularly water, wherein provision is made for initial vigorous mixing of the coagulants in the liquid followed by a gradually diminishing agitation of the liquid and flocculent to provide proper flocculation; the apparatus comprising a circular flat bottomed chamber, a central circular well having openings through its wall spaced apart circumferentially and vertically, a plurality of radially extending rotatable arms supported above the chamber, each arm carrying downwardly depending blades spaced apart along the length of the arms and positioned to intersperse with a plurality of series of vertical fixed blades extending radially from the well, and upwardly from the floor of the chamber, the blades extending substantially the full depth of the chamber, at least one feed chamber in communication with the chamber through an opening in the wall thereof, means for rotating the arms and an outlet from the bottom of the well lead

Abstract: A sluice gate including a closure member comprising a sheet of flexible fabric reinforced polymeric material having pairs of reinforcing members extending horizontally across the sheet with one member of each pair located on the upstream side and the other on the downstream side of the sheet in use. The pairs of members are secured together with the flexible sheet between them and at least some of the members on the upstream side extend beyond the side edges of the sluice opening to be controlled and those on the downstream side are able to pass into the sluice opening. The sluice gate includes control means for drawing the lower end of the closure member upwardly and away from the opening to progressively open it and to allow the closure member to return progressively to the closed position.

Abstract: This invention relates to a backwash outlet assembly for a liquid particulate filter. The outlet is adapted to retain particles which comprise the filter medium while allowing backwash liquid together with impurities to discharge to waste. The outlet comprises an outlet weir, and a substantially non-turbulent flow zone located upstream of the weir. A particle return passage extends from the floor of the zone to the filter bed and means are included to at least restrict back flow in the passage. Filter media particles carried in suspension in the backwash liquid fall under the action of gravity to the floor of the zone and by the velocity of the backwash liquid into the entrance to the return passage. Preferably the particle return passage extends from the zone adjacent the weir and filter media particles trapped in the return passage are automatically conveyed back to the filter.