A process and apparatus for protecting a media bed filter with underlying support screen from solids contained in a liquid, such as filtrate from the filter, used to regenerate or backwash the media bed filter. Filtrate enters a first collection chamber containing a screen assembly covering one outlet, the chamber also containing a second outlet. Filtrate traverses the screen assembly and is transferred to a second collection chamber with addition of a predetermined amount of bactericide to prevent solids growth therein. Upon bactericide-treated filtrate reaching a predetermined level within the second chamber, filtrate in the first chamber bypasses the screen assembly and flows out the second output to further biological treatment or use. Bactericide-treated filtrate from the second collection chamber is used to regenerate or backwash the media bed filter with addition of optional surfactant to assist in cleaning the filter media and underlying support screen. The first collection chamber has an alarm system which detects resistance of filtrate flow traversing the screen assembly and warns that the screen assembly requires cleaning or replacement, thus fully protecting the support screen from solids.
The present invention comprises apparatus and a method of automatically controlling the permeability of filter beds. In particular, this invention directs itself to filter beds or tanks that are divided into a plurality of contiguous compartments or cells, each compartment containing a filtering media substrate, which substrate is cleansed or backwashed, periodically, when necessary, by a traveling bridge backwash mechanism. The duration and frequency of backwashing is automatically controlled to maintain a desired overall permeability and throughput performance of the filter bed. Permeability control is dynamic to maintain optimum performance under all conditions, i.e. changing in response to fluctuating filter bed hydraulic or solids loading rates.
An improved method for operating a down-flow granular medium filter is disclosed which increases the effective filtration time between backwashes. The filter tank cell is divided into a plurality of subcells, each individually adapted and controlled for periodic intermittent upwardly-directed pulses of fluid passed through the filter bed within each subcell from an array of orifices beneath or in the bed. During the filtration run, one subcell is pulsed to improve the porosity of that portion of the filter bed while the remainder of the subcells continue to filter wastewater. After initiation of the first pulsing cycle for a subcell, additional subcell pulsing cycles are initiated sequentially. At the end of the filtration run the whole filter cell is backwashed to remove particulate matter from the bed and prepare the bed for the next filtration run.
A device for measuring concentration of a flowing suspension wherein a moveable detector body (3) is arranged for detecting the resistance against movement in the suspension, and including a flow modifying element (4) for bringing a portion of the suspension which is representative of the concentration of the suspension flow to the region of the detector element (3). The invention is distinguished by the flow modifying element being a fixed deflector (4), which is arranged to deflect a boundary layer (7) of the suspension flow closest to the conduit wall (1) such that it is brought away from the region of the detector body (3). The invention also concerns a method for measuring concentration and a deflector.
An improved apparatus and method for operating a granular medium filter is disclosed. The apparatus comprises an improved underdrain structure made up of a plurality of rectangular compartments which allows the filter bed to be "air pulsed" as well as backwashed for thorough cleaning of the bed. Nozzles are positioned within the rectangular compartments and directed vertically into the filter bed. Fluid from the nozzles helps to break up the bed during backwashing as well as countereact size classification of the medium during this process. The method of operating a filter with the improved underdrain structure is also described.
An improved method for constructing filter underdrain systems may be provided which uses prefabricated underdrain cells. The prefabricated underdrain cells may have a one piece construction having side walls and a bottom. The side walls may include a porous plate support ledge with a ridge at the center of the ledge. The ridge helps ensure that the sealant forms a uniform and effective gasket when the porous plates are installed.
