Abstract: Air grid systems for distributing a gas within treatment systems such as underdrain filters and contact clarifiers is disclosed. The air grid is supported from above so that it can be lowered into position and thus modified or repaired. Additionally, this feature permits retrofitting an air grid into an existing system, such as an underdrain filter, in which the bed of media overlying the underdrain is not upset by the installation. Thus, methods of installing or retrofitting air grid systems are also disclosed. In another aspect of the present invention, the air grid is comprised of an air manifold connected to air laterals by a spreader conduit that is inserted through a smooth bore in the walls of the manifold, thereby providing a simple and easy to manufacture structure that avoids problems found in prior art components.

Abstract: A system for distributing both gas and liquid in separate conduits within an underdrain filtration system is disclosed. A tubular liquid conducting conduit also contains a separate air conduit. Extending from each conduit are, respectively, liquid conducting laterals and air laterals. The system is placed within a bed of gravel at the bottom of a filter bed and acts as conventional underdrain blocks and air grids. In a downflow mode, effluent is filtered as it passes through the filter media and filtered water is collected through orifices in the liquid conducting laterals, which in turn feed into the liquid conducting conduit to form a filtrate stream. In a backwash mode, backwash liquid flows through the liquid conducting conduit, out the laterals and up through the filter bed. During backwash, air may be introduced through the air conduit and laterals and rise through the filter media to enhance the effectiveness of the backwash operation.

Abstract: A method of washing an upflow filter between service runs employs a filter bed having a non-buoyant particulate filter layer through which influent to be filtered is directed in an upward direction, and through which liquid employed in the washing operation is directed in an upflow direction. A two-stage washing operation includes the steps of first directing a combination of air and liquid in an upflow direction through the filter layer with the velocity of the liquid being less than the minimum fluidization velocity of the filter layer, for disrupting only some floc retained in the filter layer during a previous service run, and thereafter directing only liquid in an upflow direction through the filter layer at a velocity less than the minimum fluidization velocity of the filter layer for removing disrupted floc from the filter layer while leaving some floc attached to said particulate media of the filter layer.

Abstract: A method of washing an upflow filter between service runs employs a filter bed having a non-buoyant particulate filter layer through which influent to be filtered is directed in an upward direction, and through which liquid employed in the washing operation is directed in an upflow direction. A two-stage washing operation includes the steps of first directing a combination of air and liquid in an upflow direction through the filter layer with the velocity of the liquid being less than the minimum fluidization velocity of the filter layer, for disrupting only some floc retained in the filter layer during a previous service run, and thereafter directing only liquid in an upflow direction through the filter layer at a velocity less than the minimum fluidization velocity of the filter layer for removing disrupted floc from the filter layer while leaving some floc attached to said particulate media of the filter layer.

Abstract: Nozzles for use on a rotary agitator of a water and/or waste water filter system have an outer housing including a rear section through which the nozzle is connectable to the rotary agitator, and a forward wall including a plurality of ports therethrough. Fluid passage means extend from the rear connecting means to the ports for transmitting fluid from the agitator through the ports.

Abstract: A method of washing an upflow filter between service runs employs a filter bed having a non-buoyant particulate filter layer through which influent to be filtered is directed in an upward direction, and through which liquid employed in the washing operation is directed in an upflow direction. A two-stage washing operation includes the steps of first directing a combination of air and liquid in an upflow direction through the filter layer with the velocity of the liquid being less than the minimum fluidization velocity of the filter layer, for disrupting only some floc retained in the filter layer during a previous service run, and thereafter directing only liquid in an upflow direction through the filter layer at a velocity less than the minimum fluidization velocity of the filter layer for removing disrupted floc from the filter layer while leaving some floc attached to said particulate media of the filter layer.

Abstract: A rotary agitator for use in filter systems has a horizontal arm formed of a single, elongate, hollow tubular section. An opening through the peripheral wall of the tubular section at substantially the midpoint thereof communicates with the hollow interior of the tubular section. An external rotor section of a central bearing assembly is secured directly to the hollow tubular section in a region overlying the opening through the peripheral wall of the tubular section. The external rotor section has a passageway therethrough communicating with the opening through the peripheral wall of the tubular section. The central bearing assembly further includes an elongate stator positioned interiorly of the external rotor section. The passage through the elongate stator is aligned with and in communication with the opening through the peripheral wall of the tubular section.

Abstract: A filter includes a bed of particulate solids for removal of contaminants from a fluid directed in a downstream direction therethrough. A barrier is located downstream of the bed of particulate solids and includes an anchoring member having flexible members joined thereto and projecting outwardly therefrom. The flexible members are closely spaced to each other for providing a closely-spaced network of flexible members to establish multiple barrier layers in the downstream direction of fluid flow through the barrier. In one embodiment the barrier is in the form of a planar member generally coextensive with a bottom wall of the filter and includes a plurality of anchoring members spaced-apart horizontally from each other. In another embodiment the barrier is in the form of a strainer with the anchoring members being spaced-apart vertically from each other and with the flexible members joined thereto being spaced transversely along the anchoring members to provide the multiple barrier layers.

Abstract: A filter block used in the construction of a multi-block filter bottom includes upper and lower lateral sections extending between end walls and being separated from each other by a horizontal petition that includes ports for communicating the upper and lower lateral sections with each other. A removable top wall section includes passages through it for communicating with the upper lateral section, and fastening means are provided for removably securing the top wall section to the remainder of the block.

Abstract: A bottom for a filter of the type that employs granular material for removing impurities from liquids includes a trough, the bottom wall of which is interrupted by an egress passage for the granular material. Lateral wall sections of the bottom slope upwardly away from the trough toward sidewalls of the filter. An elongate header, having a central passageway therethrough, is embedded in an elongate sidewall section defining a part of the trough, and a plurality of openings are provided through an outer wall of the header and spaced-apart along the elongate extent thereof for permitting filtered liquid to pass into the header. A plurality of conduits extend laterally from the header and include central passageways communicating with the central passageway of the header. These conduits are spaced-apart along the elongate extent of the header and slope upwardly from the header toward sidewalls of the filter and are embedded in the sloping lateral wall sections of the bottom.

Abstract: A treatment facility has a granular media bed for use in acting upon (e.g. filtering) liquid mixtures, such as industrial and municipal water and wastewater, and employs a backwash operation between treatment operations for cleaning or otherwise enhancing the quality of the bed. A control system for the backwash operation establishes a first backwash rate for washing and scouring the granular media to release suspended solids and/or other impurities from the bed. Thereafter the control system establishes a second and generally greater rate for removing the released impurities from the facility. Preferably the first rate is chosen to just completely fluidize the granular bed, at which point a pressure responsive control system detects a constant differential pressure (i.e. a zero change in differential pressure), and the second rate, which generally is greater than the first rate, is responsive to the temperature of the backwash liquid.

Abstract: Biological treating systems include a treating tank for receiving wastewater to be treated, and a wastewater contacting unit mounted for reciprocating movement into and out of wastewater retained within the tank. Movement of the unit out of the wastewater exposes it to oxygen that is needed to maintain an aerobic environment for biolgical slimes, and movement of the unit into the wastewater permits these slimes to feed upon and metabolize pollutants therein. Preferably the systems include a plurality of wastewater contacting units positioned in pairs on opposite sides of axles and connected thereto. These axles are mounted for reciprocating movement, and a drive mechanism is provided to reciprocate the axles and the connected pairs of contacting units.