Patent Application
20140360591
The present invention is directed to water and/or wastewater filter systems for filtering impurities from a liquid. More particularly, the present invention is directed to components for distributing fluids through a filter bed where the filter bed has at least one layer of filter media.
Various filter systems have been developed to filter water and wastewater. Typical filter systems include but are not limited to upflow filters, upflow clarifiers, downflow filters, downflow clarifiers, bi-flow filters as well as various combinations of the aforementioned filter systems. The terms upflow filter and upflow clarifier refer to filter systems in which influent to be filtered is directed in an upward path to remove impurities. Conversely, the terms downflow filter and downflow clarifier refer to filter systems in which the influent is directed in a downward path to remove impurities. Bi-flow filters refer to filter systems in which the influent is directed in both a downward path and an upward path to remove impurities. The upflow filters/clarifiers, downflow filters/clarifiers and bi-flow filters include one or more filter beds formed from one or more layers of filter media. The filter media may be supported by one or more layers of gravel. Alternatively, the one or more gravel layers may be replaced with a porous plate or other direct retention mechanism.
In a combined system, for example, an upflow filter/clarifier followed by a downflow filter, the influent is initially directed upwardly through the upflow filter/clarifier to remove a predetermined percentage of the impurities in the influent and then directed downwardly through the downflow filter to remove the remaining impurities to within an acceptable limit. Where the filter system includes multiple downflow filters connected in series, the influent is directed downwardly through each of the downflow filters one after the other to remove the impurities within an acceptable limit.
Regardless of the type of granular bed filter system and/or the type of the liquid to be filtered, it is common for the filter system to include an underdrain. The underdrain directs and receives fluids during operation of various cycles of the filter system including the filtration cycle (also referred to as a service run) and a washing cycle. The washing cycle may be performed by directing the washing fluid in a path opposite to the path of influent during the filtration cycle or the washing cycle may be performed by directing the washing fluid in the same path as the path of the influent during the filtration cycle. The washing fluids may include influent, pre-filtered water, air or other suitable gas. A key function of the underdrain is to evenly distribute the washing fluid through the filter bed during the washing cycle so that at least a significant amount of the impurities trapped in the filter can be removed. In the event that the underdrain does not evenly distribute the washing fluid through the filter bed, the filter bed will likely not be properly cleaned. At a minimum, this will cause much shorter filtration cycles and more washing cycles. This is undesirable, as the filter system typically cannot operate in the filtration cycle during a washing cycle.
There are many different types of underdrain systems currently marketed for use in water filtration. Some underdrains are used for water only backwash and some are capable of introducing air only, water only, or simultaneous liquid and air.
A common type of underdrain is the “lateral” style. This type of underdrain is typically made of injection molded or extruded plastic or extruded clay. The underdrain blocks are arranged in rows termed “laterals”. The laterals are typically spaced on approximately 12 inch centers leaving an approximately 1 inch space between the laterals. Prior known underdrain laterals include combined air/water lateral type underdrains configured to introduce air and water simultaneously into the filter bed. However, mal-distribution is a concern with previously known combined air/water lateral type underdrains. As previously explained, mal-distribution can be problematic to the efficient operation of the filter system. Hence, a preferred form of the present invention is directed to an underdrain that eliminates or significantly reduces mal-distribution of washing fluids through a filter bed.
An object of the present invention is to provide a novel and unobvious underdrain and a method of washing a filter system using the novel and unobvious underdrain.
Another object of a preferred embodiment of the present invention is to provide a lateral type underdrain that permits a combined liquid and air wash of a filter bed and eliminates or significantly reduces mal-distribution of the combined liquid and air wash.
A further object of a preferred embodiment of the present invention is to provide an insert that can be inserted into at least a portion of an underdrain lateral to improve the washing efficiency of the underdrain lateral.
Yet another object of a preferred embodiment of the present invention is to provide a baffle assembly for an underdrain lateral that improves the washing efficiency of the underdrain lateral.
Still another object of a preferred embodiment of the present invention is to provide an insert for an underdrain lateral that reduces or eliminates mal-distribution of the washing fluid released from the underdrain lateral where the insert is designed to be inserted in the underdrain lateral subsequent to formation of the underdrain lateral.
Yet a further object a preferred form of the present invention is to provide an underdrain lateral having three chambers running substantially the length of the underdrain lateral where each of the three chambers is configured to release a combined gas and liquid wash into the filter bed.
It must be understood that no one embodiment of the present invention need include all of the aforementioned objects of the present invention. Rather, a given embodiment may include one or none of the aforementioned objects. Accordingly, these objects are not to be used to limit the scope of the claims of the present invention.
In summary, one preferred embodiment of the present invention is directed to a fluid distributor for use in a filter system for filtering water or wastewater. The fluid distributor includes a lateral having at least one chamber for receiving at least one fluid. The lateral is configured to receive and distribute at least one fluid through a filter bed of the filter system. The lateral has at least one opening. The fluid distributor further includes an insert configured to be inserted into the lateral through the opening of the lateral. The insert, when inserted into the lateral, forms at least one additional chamber in the lateral.
Another preferred embodiment of the present invention is directed to an apparatus for use in a filter system for filtering water or wastewater. The apparatus includes an underdrain lateral having at least a first chamber, a second chamber and a third chamber. A first baffle assembly having a plurality of baffles is disposed in the first chamber. The first baffle assembly forms a plurality of upper chambers in the first chamber and at least one lower chamber in the first chamber.
A further preferred embodiment of the present invention is directed to an apparatus for use in a filter system for filtering water or wastewater. The apparatus includes an underdrain lateral having at least a first chamber and a second chamber. The first chamber is in fluid communication with the second chamber. The apparatus further includes a baffle assembly having a plurality of baffles operably associated with at least one of the first chamber and the second chamber to vary at least one fluid distribution characteristic of the at least one of the first chamber and the second chamber.
Still a further preferred embodiment of the present is directed to an apparatus for use in a filter system for filtering water or wastewater. The apparatus includes an underdrain lateral. The underdrain lateral has at least a first chamber, a second chamber and a third chamber. A fluid flow control member having a substantially horizontally extending plate is disposed in the second chamber to form at least one upper chamber and at least one lower chamber. At least one of the first chamber and the third chamber is in fluid communication with the second chamber such that the at least one of the first chamber and the second chamber direct a washing gas and a washing liquid into the at least one upper chamber of the second chamber. The at least one lower chamber of the second chamber is configured to receive only a washing gas during a cleaning cycle.
The preferred forms of the invention will now be described with reference to
Referring to
Referring to
Preferrably, gas only is introduced into the lower center chamber 10 during a wash cycle utilizing simultaneous liquid and air. The gas can be introduced in the same manner as the liquid is introduced into the outer, lower chambers 8 and 12. Air can be used as the washing gas. However, any suitable gas may be used. Evacuation openings may be formed in walls 2 and 4. The evacuation openings may be spaced along the length of the underdrain lateral to allow any residual water in center chamber 10 remaining from a filtration cycle to pass into chambers 8 and 12. The height of the evacuation openings may be varied along the length of the underdrain lateral A to compensate for velocity head or friction loss. Lower, center chamber 10 is in fluid communication with upper, center chamber 16 via a plurality of primary internal air distribution orifices 24 disposed above inner, lower chamber 10. Preferably, orifices 24 extend the length of underdrain lateral A. Openings 28 and 30 are formed in walls 2 and 4, respectively to allow the washing gas to pass from chamber 16 to chambers 14 and 18.
Referring to
Lower, outer chambers 8 and 12 are in fluid communication with chambers 14 and 18, respectively via orifices (not shown) formed in internal wall 6 above outer, lower chambers 8 and 12. These orifices are preferably uniformly spaced along the length of the underdrain lateral A in a similar manner as orifices 24. The orifices in internal wall 6 above outer, lower chambers 8 and 12 allow the washing fluid in chamber 8 and 12 to pass into lower chamber 40 of the corresponding outer, upper chambers 14 and 18. Orifices 50 in plates 32 allow washing fluid in lower chambers 40 to pass into each of the plurality of upper chambers 48 of the outer upper chambers 14 and 18.
The location of openings 28 and 30 above the corresponding plates 32 introduces the washing gas from inner, upper chamber 16 into each of the upper chambers 48 of the outer upper chambers 14 and 18 where the washing gas is mixed with the washing liquid thereby bypassing lower chambers 40. Notably, chambers 40 during a cleaning cycle receive substantially only a washing liquid.
In the preferred form of underdrain lateral A, top surface 52 includes a plurality of slots 54 formed therein above the upper outer chambers 14 and 18. It will be readily appreciated that slots may also be formed in top surface 19 above upper chamber 16. The slots 54 allow the underdrain lateral A to release from the upper chambers 14, 16 and 18 a washing liquid and a washing gas into the filter bed supported by underdrain laterals A. Slots 54 are preferably formed using a laser to cut the slots into top surface 52. The width of the slots is relatively narrow to prevent media supported directly by the underdrain lateral from passing through and/or clogging slots 54 obviating the need for a porous plate or other separate media support member. In the most preferred form, each slot 54 has a length of 1.5 inches and a width of 0.0115 inches. However, the length and width of the slots can be readily varied as desired. For example, where the underdrain lateral A is used in connection with filtration of wastewater, the width of the slots 54 can be considerably larger due to the larger size media used in filtration of wastewater. Larger size slots can be formed using techniques other than laser cutting. Further, the shape of the slots can be readily varied and can include circular openings.
However, in the event that a porous plate is used, underdrain lateral A may include rails 56 and 58, as seen in
Preferably, baffle assembly C is configured so that baffle assembly can be inserted after the underdrain lateral has been formed. Hence, the baffle assembly C could be used to retrofit existing underdrain laterals. The baffle assembly C may be formed from the same material as the underdrain lateral or any other suitable material. Preferably, the baffle assembly is formed from PVC.
During a filtration cycle, all portions of all of the six chambers 8, 10, 12, 14, 16 and 18 are filled with liquid. Where the filter is a downflow filter, filtered water flows downwardly through underdrain lateral A into a flume or other channel means to remove the effluent from the filter. During a gas only wash cycle, gas such as air is introduced into chamber 10. Air will be metered into chamber 16 via orifices 24. Air will pass into upper chambers 48 of outer, upper chambers 14 and 18 through orifices 28 and 30, respectively and escape into the filter through slots 54. If slots are disposed above chamber 16, air will also be released into the filter bed directly from chamber 16.
During a simultaneous liquid and gas wash cycle, air is introduced in underdrain lateral A and the filter bed in the same manner as described above. Simultaneously, a washing liquid is introduced into the lower, outer chambers 8 and 12. The washing liquid travels from lower, outer chambers 8 and 12 into the lower chamber 40 of the corresponding outer, upper chambers 14 and 18. The washing liquid passes from lower chamber 40 of the outer, upper chamber 14 and 18 into each of the upper chambers 48 of the outer, upper chamber 14 and 18 where it mixes with the washing gas. Combined liquid and gas flow into the filter bed through slots 54 formed above outer, upper chambers 14 and 18. If slots 54 are formed above inner, upper chamber 16, gas only will flow into the bed through slots 54 formed above inner, upper chamber 16 at the same time liquid and air is released into the bed from chambers 14 and 18.
During liquid only wash cycle, liquid is introduced into chambers 8 and 12 and distributed as described above. Notably, just liquid will flow through slots 54.
Underdrain lateral D depicted in
Referring to
While this invention has been described as having a preferred design, it is understood that the preferred design can be further modified or adapted following in general the principles of the invention and including but not limited to such departures from the present invention as come within the known or customary practice in the art to which the invention pertains. The claims are not limited to the preferred embodiment and have been written to preclude such a narrow construction using the principles of claim differentiation.
