US 4,627,923 A · Apparatus and method of filtering solids from a liquid effluent

Abstract

There is provided an improvement in a waste effluent filter of the type including a tank, a generally flat fine mesh screen over the lower portion of the tank to define an underdrain cavity below the screen and a filter bed of particulate material having an upper surface and a lower general surface adjacent the underdrain cavity. The particle size of the particulate material being greater than the size of the apertures in the fine mesh screen. The filter improvement includes a jet creating grid for creating a plurality of upwardly directed hydraulic jets evenly distributed throughout the filter bed during the filtering of the effluent through the bed wherein the jet creating grid includes a plurality of nozzles in the bed itself substantially below the upper surface of the bed and above the fine mesh screen a selected distance to retain the lower layer of the bed undisturbed. As a further improvement a plurality of horizontal liquid jets are created as a network over the upper surface of the sand bed to scour the media surface during filtering. A further improvement in the filter is the creation of a plurality of hydraulic cleaning jets usable during backwashing along with a vertical flushing action through the screen from the underdrain cavity. Yet a further improvement in the filter is the provision of a chemical cleaning feature utilizing two separate and distinct chemicals injected into the bed for cleaning the filter bed. Preferably, the chemical injection uses the two sets of vertically displaced jets.

Claims45

Dependent claims

Method of operating a waste effluent filter including a tank having a lower portion;

a generally flat fine mesh element supported adjacent said lower portion and having a multitude of apertures;
an underdrain cavity adjacent said lower portion and under said fine mesh element and generally coextensive with said fine mesh element;
a filter bed of particulate material having an upper surface;
a parallel lower surface on said generally flat fine mesh element, a generally uniform depth between said fine mesh element and said upper surface and an effective particle size at least greater than the size of said apertures of said fine mesh elements;
means for directing effluent into said filter above said upper surface;
and, means for directing filtered effluent from said underdrain cavity, said method comprising the steps of:
(a) allowing liquid in said tank to increase to a level substantially above said upper surface during filtering;
and,
(b) during such filtering, periodically regenerating said upper surface by folding filtered material at said upper surface into said filter bed by directing a plurality of evenly distributed hydraulic jets upwardly through said filter bed from a position in said bed and above said flat fine mesh element a given distance whereby a lower filtering layer of said bed remains undisturbed between said jets and said fine mesh element while said upper surface is regenerated.

6 more elements

In a waste effluent filter including a tank having a lower portion;

a generally flat fine mesh element supported adjacent said lower portion and having a multitude of apertures;
an underdrain cavity adjacent said lower portion and under said fine mesh element and generally coextensive with said fine mesh element;
a filter bed of particulate material having an upper surface, a parallel lower surface on said generally flat fine mesh element, a generally uniform depth between said fine mesh element and said upper surface and an effective particle size at least greater than the size of said apertures of said fine mesh element;
means for directing effluent into said filter above said upper surface;
and, backwash means for directing filtered effluent from said underdrain cavity, the improvement comprising:
jet creating means for selectively creating a plurality of upwardly directed hydraulic jets evenly distributed throughout said filter bed during filtering of said effluent through said filter bed to regenerate said upper surface periodically, said jet creating means including a plurality of nozzles evenly distributed in said bed, substantially below said upper surface and above said flat fine mesh element a selected distance to retain a lower layer of said bed generally undisturbed during surface regeneration by operation of said hydraulic jets.

3 more elements

In a waste effluent filter including a tank having a lower portion;

a generally flat fine mesh element supported adjacent said lower portion and having a multitude of apertures;
an underdrain cavity adjacent said lower portion and under said fine mesh element and generally coextensive with said fine mesh element;
a filter bed of particulate material having an upper surface, a parallel lower surface on said generally flat fine mesh element, a generally uniform depth between said fine mesh element and said upper surface and an effective particle size at least greater than the size of said apertures of said fine mesh element;
means for directing effluent into said filter above said upper surface;
and, means for directing filtered effluent from said underdrain cavity, the improvement comprising:
an hydraulic means for creating a plurality of horizontal liquid jets at a given location above said upper surface of said bed and evenly distributed across said bed and means for energizing said hydraulic means when liquid above said filter bed exceeds a given level higher than said given location.

3 more elements

In a waste effluent filter including a tank having a lower portion;

a generally flat fine mesh element supported adjacent said lower portion and having a multitude of apertures;
an underdrain cavity adjacent said lower portion and under said fine mesh element and generally coextensive with said fine mesh element;
a filter bed of particulate material having an upper surface, a parallel lower surface on said generally flat fine mesh element, a generally uniform depth between said fine mesh element and said upper surface of said bed and an effective particle size at least greater than the size of said apertures of said fine mesh element;
means for directing effluent into said filter above said upper surface;
and, means for directing filtered effluent from said underdrain cavity through said bed for backwashing during times between filtering by said bed, the improvement comprising:
a first network of upwardly facing nozzles evenly spaced throughout said bed, substantially below said upper surface of said bed and above said flat fine mesh element a selected distance to retain a lower layer of said bed generally undisturbed when jets are directed through the upper portion of said bed above said nozzles, means for forcing filtered effluent through said nozzles of said first network in a series of bed surface regenerating cycles during filtering by said bed between backwashing of said total bed by a means for forcing liquid from said underdrain upwardly through said total bed including said retained lower layer.

3 more elements

Dependencies are inferred from the claim text.

Apparatus and method of filtering solids from a liquid effluent

Life of this patent

Apparatus and method of filtering solids from a liquid effluent

Life of this patent

Abstract

Claims45