A filter is provided including a vessel having an input positioned near the top of the vessel for contaminated fluid; the vessel containing media; a drain screen; a propeller rotatable on a drive shaft extending downwardly from the top of the vessel; a deflector plate below the drain screen to impel media outwardly from the center of the vessel; a plurality of baffles positioned on side walls of the vessel; and a drain to remove fluid from the vessel.

A filtration apparatus includes a filtration tank; a layer of filtration media that filters supplied raw water by passing the raw water therethrough within the interior of the filtration tank; and a screw cleansing mechanism having a cylindrical outer cylinder which is provided within the filtration tank in a vertical orientation, a spiral shaped screw which is provided such that the long axis thereof extends in the longitudinal direction of the outer cylinder, and a screw driving member for rotating the screw, that scrubs and cleans filtration media by rotating the screw. The screw is in the shape of a coil spring.

A modular underdrain system is disclosed. The modular underdrain system may comprise an intermediate modular component having a first peripheral side including a first mating portion and a second peripheral side including a second mating portion. The second mating portion may be sized and shaped to engage with a first mating portion of an adjacent modular component. A modular component chamber may be bounded by an underdrain floor side and an internal side. The underdrain floor side may comprise a plurality of slots. The metering pipe is sized to be positioned within a metering pipe opening in the internal side with a distributor head positioned within the modular component chamber. The metering pipe may comprise a set of one or more remote orifices and a set of one or more proximate orifices.

A media filter includes an inlet and a diffuser located axially below the inlet for distributing liquid entering the filter via the inlet over the media in the filter. The diffuser including one or more members extending generally orthogonal to the axis of the filter.

A filter is provided including a vessel having an input positioned near the top of the vessel for contaminated fluid; the vessel containing media; a drain screen; a propeller rotatable on a drive shaft extending downwardly from the top of the vessel; a deflector plate below the drain screen to impel media outwardly from the center of the vessel; a plurality of baffles positioned on side walls of the vessel; and a drain to remove fluid from the vessel.

A filter is provided including a vessel having an input positioned near the top of the vessel for contaminated fluid; the vessel containing media; a drain screen; a propeller rotatable on a drive shaft extending downwardly from the top of the vessel; a deflector plate below the drain screen to impel media outwardly from the center of the vessel; a plurality of baffles positioned on side walls of the vessel; and a drain to remove fluid from the vessel.

A particulate filtering device with a multi-layer water distribution and collection structure and a method for using the same are provided. The device includes a tank where a filtering space and a back flushing expansion space are formed. An upper water distribution pipe is arranged above the back flushing expansion space and is in communication with an ozone gas-water mixing pipe. Ozone enters the back flushing expansion space through the upper water distribution pipe and mix with water for reaction. Exhaust gas is discharged from the top of the tank. Powdered activated carbon may enter the tank through the upper water distribution pipe, and is intercepted at a space above the filtering space to form an activated carbon layer, to absorb organics dissolved in the water and catalytically decompose ozone. At least three water distribution and collection pipes are arranged on a layer basis in the filtering space.

An underdrain block for filtering water includes a top wall, a bottom wall, and two side walls connecting the top wall to the bottom wall to define an internal chamber. The bottom wall contains a plurality of orifices that allow liquid and solid materials to enter and exit the internal chamber. An underdrain filtering system can be formed by securing an underdrain lateral, which is formed from one or a plurality of underdrain blocks, to a filter floor. Also included is a method of preparing an underdrain lateral for providing even distribution of backwash water along the underdrain lateral and a method of validating even distribution of backwash water across an underdrain lateral.

An underdrain block for filtering water includes a top wall, a bottom wall, and two side walls connecting the top wall to the bottom wall to define an internal chamber. The bottom wall contains a plurality of orifices that allow liquid and solid materials to enter and exit the internal chamber. An underdrain filtering system can be formed by securing an underdrain lateral, which is formed from one or a plurality of underdrain blocks, to a filter floor. Also included is a method of preparing an underdrain lateral for providing even distribution of backwash water along the underdrain lateral and a method of validating even distribution of backwash water across an underdrain lateral.

The present disclosure provides improved methods for conducting a wash cycle in a filtration unit. The methods may be used alone or in combination with one another to achieve the improvements described herein. Filtration units adapted for carrying out the novel methods are also provided. Through the use of the methods and filtration units described, significant economic benefits are obtained without a significant increase in the costs of the filtration unit or in the costs of operation of the filtration unit.