A water intake and pretreatment system (10) comprising an inlet for delivering water from a natural source to a reservoir (12); said inlet to reservoir having a net screen (16) to prevent entry of organisms above a predetermined size and including a one-way gate (30) to allow organisms to exit the reservoir; said reservoir further comprising a granular filter media for water and algae filtration; and a drainage layer for removal of filtered water from the granular filter media to a drainage outlet. A local backwashing apparatus 40) is included for localized backwashing of the granular filter media.

This disclosure relates to filtration screens for use in a backwashable granular media bed filtration system. Drop-in retrofit kits for a backwashable granular media bed filtration system comprising one or more filtrations screens are provided herein. Such screens and kits can comprise a media support screen, a backwash filter screen, or a combination thereof. The kit can further comprise an agitator element comprising an impeller having vanes in which the impeller vane surfaces are coated with an abrasion resistant material. Associated filtration systems and processes are also described herein.

A biological treatment apparatus comprising: (a) a vessel; (b) an inlet conduit for providing feed water to an inlet region; (c) an outlet conduit for removal of treated water from an outlet region; (d) an inlet distributor comprising inlet ducts, each in fluid communication with both the inlet region and a porous surface section of the inlet duct wall; (e) an outlet distributor comprising a plurality of outlet ducts, each in fluid communication with both the outlet region and a porous surface section of the outlet duct wall; and (f) a media bed comprising particles in fluid communication with porous surface sections of both the inlet and outlet duct walls; wherein a ratio of the length of an inlet duct to a minimum distance between an inlet duct and an outlet duct is from 15:1 to 2:1.

To provide a filter medium, a process for producing filter medium, a filtration device, a method for operating the filtration device, and a filtration system, which are capable of promptly regenerating the adsorption power by backwashing and realizing efficient operation of a filtration device. The filter medium of the present invention contains a carbon-based material in which a cumulative pore volume of pores having a pore radius of 2 nm or less is 25% or less with respect to a cumulative pore volume of pores having a pore radius of 50 nm or less.

The present invention relates to a filtering apparatus (1) for the filtration of liquids, in particular water. It comprises, inside a container (11), a first chamber (50) intended to receive liquid to be filtered, a second chamber (54) intended to receive filtered liquid, a first porous wall (51) and a second porous wall (53) which delimit a filtration chamber (40) between them. The first porous wall (51) divides the first chamber (50) from the filtration chamber (40) and the second porous wall (53) divides the second chamber (54) from the filtration chamber (40), so that the filtration chamber (40) is interposed between the first chamber (50) and the second chamber (54). A granular filter material (4) is housed in the filtration chamber (40) and is enclosed between the first porous wall (51) and the second porous wall (53). The first chamber (50) receives the liquid to be filtered at a first height (H1) which is at a higher altitude than the second height (H2) at which the second chamber (54) discharges the filtered liquid. The first chamber (50), the filtration chamber (40) and the second chamber (54) are flanked to each other and, in a section between the first height (H1) and the second height (H2), are all intersected by a plurality of horizontal planes (P) parallel to each other. In use, the liquid to be filtered passes from the first chamber (50) to the second chamber (54) substantially by gravity and through the filtration chamber (40) with a flow path having a horizontal component.

A filtration device comprising a media basket, a baseplate, and a canister. The media basket is affixed to the baseplate. The canister has a cavity therein and is detachably coupled with the baseplate to enclose the media basket. The media basket contains a porous filtration material that efficiently removes contaminants from liquid. The device is configured to establish a first siphon to convey liquid from outside the device into the canister cavity through a canister pipe when a liquid level outside the filtration device is higher than the top of the weir in the canister pipe and configured to establish a second siphon to convey liquid from canister cavity through the top of a center riser pipe and out an outlet pipe when the first siphon has been established and the liquid level outside the filtration device is higher than the top of the center riser pipe.

Systems, devices, and methods for providing nutrient removals in an up flow filtration storm water system for treating water to very high clean levels using filtration media. A filtration media can be supported by a screen above a floor in a vault allows for incoming storm water to pass into a void space above the floor into the screen and filtration media and then out an outlet to the vault. The filtration media can include recyclable and/or natural particles. Layers of river rocks can be placed on top of and below the filtration media. The captured debris can drop to the floor. The long lasting filtration media can be cleaned by being backwashed.

An apparatus for removing impurities from water and/or wastewater and a method of installing a fluid distribution system in the apparatus. In the most preferred form of the invention, the fluid distribution system is an air scour system for directing air through the filter bed to assist in cleaning of the filter bed to remove impurities trapped in the filter bed during a service run. In the most preferred form, the method of installing the fluid distribution system in the filter bed is performed by imparting a force to the filter bed to permit the fluid distribution system to be installed in the filter bed without removing media. The fluid distribution system is preferably configured to permit the fluid distribution system to be readily installed in the filter bed and at an optimum orientation.

Underdrain units in a sand medium or dual medium filtration system include efficient air, water and combined air/water cleaning. Air, water or both are delivered in backflow direction from a very low position on the underdrain unit, as well as water from a higher position, so as to effectively remove blocking contaminants on the outside the underdrain unit and in the surrounding filter media.

A water treatment filter backwash process control system, comprising a control system that receives filter level data and filter backwash turbidity data. The control system having a filter level set point, wherein the filter level set point corresponds to a desired filter media bed expansion. The control system having a filter backwash turbidity set point, wherein the control system controls the filter backwash process by, while monitoring the filter backwash turbidity, sending one or more output signals that are used to control a backwash inlet liquid flow in order to maintain a desired media bed expansion, and stop the backwash inlet liquid flow when the filter backwash turbidity set point is reached.