Abstract: An underdrain block including a top wall, a bottom wall, and a pair of sidewalls defining a hollow interior and having a longitudinal axis, wherein the sidewalls, top wall, or both comprise at least one external detail. A handle is detachably connected to the external detail for transportation and positioning of said underdrain block. The external detail may comprise one of a protrusion or a receptacle for receiving a protrusion and the handle may include the other of a protrusion or a receptacle for receiving a protrusion. Also, a method of installing an underdrain block lateral comprising at least one underdrain block including the steps of attaching a handle to external details on the underdrain block, lifting the underdrain block lateral by the handle, positioning the underdrain block lateral into the underdrain system, and detaching the handle from the external details of the underdrain block.

Abstract: An underdrain filter block for use in draining and backwashing a filtering media in a filter bed includes a top wall, a pair of side walls extending from the top wall, and a bottom wall extending between the pair of side walls. The top wall, the pair of side walls, and the bottom wall define an upper portion and a lower portion. The lower portion includes a grout chamber having a plurality of openings defined by at least one of the bottom wall and the pair of side walls.

Abstract: A filter system for filtering a liquid containing particles including a single media retainer plate having a top and bottom surface, and defining at least one hopper-shaped compartment having a sloped wall defining a slot spanning the top and bottom surfaces is disclosed. The plate also includes at least one baffle extending from the bottom surface and filter media disposed on the top surface. During a filtering operation of the filter system, the filter media captures the particles, such as dirt, from the liquid as the liquid passes through the filter media to an underdrain system. During a backwash operation of the filter system, the baffle is adapted to direct a backwash fluid in a vertical direction through the slot so that the backwash fluid actuates the filter media to scour the top surface of the plate and prevent the build-up of biological scaling on the plate.

Abstract: An underdrain system for transferring forces and directing flow includes at least one underdrain block having a top wall, a bottom wall, and two side walls connecting the top wall to the bottom wall to define a block interior. An insert is disposed in the interior of the underdrain block. The insert includes force-transmitting buttresses spaced along an exterior of the insert that contacts the two side walls of the underdrain block and act to transfer downward forces acting on the top wall of the underdrain block and internal fluid forces acting on the insert to the side walls of the underdrain block. The force-transmitting buttresses can also direct hydraulic flow.

Abstract: A media retainer assembly for retaining filter media in a filter assembly includes a top plate for supporting the filter media, the top plate having a top surface, a bottom surface and a plurality of openings extending therethrough; a bottom plate having a top surface and a plurality of openings extending therethrough; and scouring media, the scouring media being adapted to abrade the surfaces of the top and bottom plates. The top plate is connected to the bottom plate such that the top surface of the bottom plate is spaced from the bottom surface of the top plate to define at least one chamber between the top plate and the bottom plate. The top surface of the top plate is in fluid communication with the chamber via the openings in the top plate. The scouring media is supported by the bottom plate within the at least one chamber.

Abstract: A filter system having a filter media retainer seal includes: at least one underdrain block having a top wall, a bottom wall, and a pair of side walls extending between the top wall and the bottom wall; a filter media retainer mounted onto the top wall of the at least one underdrain block; and at least one rib positioned between the underdrain block and the filter media retainer. The at least one rib forms a seal between the underdrain block and the filter media retainer, and prevents filter media from entering the underdrain block. The at least one rib can be monolithically formed to the at least one underdrain block. Alternatively, the at least one rib is monolithically formed to the filter media retainer. The rib is crushable and/or it bites into a surface on the adjoining part to reduce or eliminate the need for a separate sealant.

Abstract: A method of distributing gas and liquid through an underdrain system includes: a) positioning an underdrain system on a filter floor, the underdrain system comprising at least one underdrain block and filter media positioned on top of the underdrain block; b) distributing gas sufficiently evenly through the underdrain system at a rate of less than 2 scfm/ft2 by distributing a liquid at a rate of less than 2 gpm/ft2 concurrently with the gas; c) increasing the distribution rate of the liquid, or increasing the distribution rate of the liquid and the distribution rate of the gas; d) stopping the distribution of gas; e) further increasing the distribution rate of the liquid; and f) decreasing the distribution rate of the liquid. A method of distributing gas and liquid during an upflow filtration mode is also included.

Abstract: A media retainer assembly for retaining filter media in a filter assembly includes a top plate for supporting the filter media, the top plate having a top surface, a bottom surface and a plurality of openings extending therethrough; a bottom plate having a top surface and a plurality of openings extending therethrough; and scouring media, the scouring media being adapted to abrade the surfaces of the top and bottom plates. The top plate is connected to the bottom plate such that the top surface of the bottom plate is spaced from the bottom surface of the top plate to define at least one chamber between the top plate and the bottom plate. The top surface of the top plate is in fluid communication with the chamber via the openings in the top plate. The scouring media is supported by the bottom plate within the at least one chamber.

Abstract: A filter system for filtering particles from a liquid includes an underdrain assembly having an underdrain defining at least one underdrain chamber and a media retainer assembly. The media retainer assembly includes an upper filter media retainer plate defining a plurality of hopper-shaped cavities and a lower filter media retainer plate defining a plurality of hopper-shaped cavities corresponding to the plurality of hopper-shaped cavities on the upper plate. The plates are in a nested arrangement such that the hopper-shaped cavities on the upper plate are in alignment with the corresponding plurality of hopper-shaped cavities on the lower plate to define a plurality of passages therebetween and allow for the passage of the liquid while preventing the passage of a filter media. During a backwash operation, the upper and lower plates are relatively moveable such that the backwash fluid releases any particles lodged in the passages between the plates.

Abstract: An underdrain filter block for use in draining and backwashing a filtering media in a filter bed includes a top wall, a pair of side walls extending from the top wall, a bottom wall extending between the pair of side walls, and a transverse wall extending from one of the pair of side walls to the other of the pair of side walls. The top wall, the pair of side walls, and the bottom wall define an upper portion and a lower portion. The lower portion includes a grout chamber positioned between the bottom wall and the transverse wall and at least one of the bottom wall and said side walls contains an opening.

Abstract: A filter system for filtering a liquid containing particles including a single media retainer plate having a top and bottom surface, and defining at least one hopper-shaped compartment having a sloped wall defining a slot spanning the top and bottom surfaces is disclosed. The plate also includes at least one baffle extending from the bottom surface and filter media disposed on the top surface. During a filtering operation of the filter system, the filter media captures the particles, such as dirt, from the liquid as the liquid passes through the filter media to an underdrain system. During a backwash operation of the filter system, the baffle is adapted to direct a backwash fluid in a vertical direction through the slot so that the backwash fluid actuates the filter media to scour the top surface of the plate and prevent the build-up of biological scaling on the plate.

Abstract: A method and system for removing nitrogen from a downflow denitrification media filter which optimizes the bump timing increasing productivity. The method comprises measuring the influent and effluent nitrate concentrations and determining total nitrate-nitrogen accumulation. A bump of the filter is initiated based on a comparison of the total nitrate-nitrogen accumulation with a predetermined accumulated nitrate-nitrogen value. The method may utilize a processor, having a memory, which is capable of communicating with, receiving input from and sending output to, and controlling the filter and any in-line measurement tools. The method may include a bump timing factor to adjust the bump interval when the actual operating conditions are substantially different from the operating conditions that were present when the predetermined accumulated nitrate-nitrogen value was determined. A method for predicting the bump interval and determination of an estimated time until the next bump are also included.

Abstract: An adjustable anchor rod arrangement for use with an underdrain system that includes the a pair of spaced apart legs and an elongated member adjustably attached to the legs, wherein the legs are adjustable along a longitudinal axis of the elongated member and the elongated member is adjustable along a longitudinal axis of the legs.

Abstract: The present invention is related to a method and system for cleaning a media support structure in a filter cell in a liquid filter system, wherein a cleaning solution does not significantly enter a filter media zone. The method comprises supplying a cleaning solution to a filter cell to a level sufficient to submerge the media support structure, but not to significantly enter the filter media zone. Additionally, the cleaning solution level is monitored to ensure the cleaning solution does not significantly enter the filter media zone. Alternatively, the cleaning solution may be continuously recirculated and reintroduced to the filter cell during the cleaning operation.

Abstract: A process for optimizing the carbon feed in a denitrification filter. The process utilizes in-line or off-line measurements of process variables in combination with feed forward and feedback control and increases or decreases the amount of carbon added based on a calculated reset rate determined on a periodic basis. The calculated reset rate may be a percentage of a theoretical value of the necessary carbon feed rate needed to remove the desired amount of nitrate-nitrogen. When the effluent nitrate-nitrogen is at a desired level and no rate change is necessary, the carbon feed rate is set to an average of one or more of the last filter runs. The process may also include a step wherein the carbon addition is increased immediately after backwashing to reestablish the biomass needed to produce the desired effluent in a step to regain process efficiency once that boost reestablishes the biomass.

Abstract: A backwash distribution apparatus for a filter having a filter tank and a plurality of underdrain laterals includes a first and second separator device positioned in a common main conduit to define first and second auxiliary flumes. The first and second auxiliary flumes are in fluid communication with the common main conduit and the underdrain laterals. The first separator device has at least one flume liquid metering orifice preferably located near the bottom of the first separator device so that it may be below a gas liquid interface in the first auxiliary flume. The second separator device has either a weir edge or a plurality of metering orifices (or both) for passing backwash liquid from the common main conduit into the second auxiliary flume.