US2209602A - Method of and apparatus for rapid sand filtration - Google Patents

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July 30, 1940 JEWELL 2,209,602

METHOD OF AND APPARATUS FOR RAPID SAND FILTRATION Original Filed Nov. 26. 193:5 e Sheets-Sheet 1 July so, 1940. '1. H. EWELL 2,209,602

METHOD OF, AND APPARATUS FOR RAPID SAND FILTRATION Original Filed Nov. 20, 1933 July 30, 1940. l. H. JEWELL 2,209,602

METHOD OF AND APPARATUS FOR RAPID SAND FILTRATION Original Filed Nov. 20, 1933 6 Sheets-Sheet 3 l I ll 3a 54 I 35 6+ 15 J 14 :5 35 34 35 7 O r 0 O 44 I 7 45 l/ N O O 4/ 4/ 0 4 4? 37 4a y 30 1940. I. H. JEWELL 2 209,602

METHOD OF AND APPARATUS FOR RAPID SAND FILTRATION Original Filed Nov. 20, 1933 6 Sheets-Sheet 4 July 30, 1940. I. H. JEWELL 2,209,602

METHOD OF AND APPARATUS FOR RAPID SAND FILTRATION Original Filed Nov. 20, 1933' 6 Sheets-Sheet 5 July 30, 1940. l. H. JEWELL 2,209,602

METHOD OF AND APPARATUS FOR RAPID SAND FILTRATION Original Filed Nov. 20, 1933 6 Sheets-Sheet 6 Patented July 30, 1940 UNITED STATES METHOD OF AND APPARATUS FOR RAPID SAND FILTRATION Ira H. Jewell, Evanston, 111.

Application November 20, 1933, Serial No. 698,852 Renewed January 4, 1939 7 Claims.

My invention is concerned with rapid sand filtration, primarily with a novel structure adapted to be added to, or initially form a part of, the ordinary rapid sand filter, such as are used by municipalities, and serving to modify its method of operation and materially increase not only its capacity per hour, but also to extend the time during which it can operate without washing. It also serves materially to improve the washing of the sand, as will be hereinafter explained,

As ordinarily constructed, a rapid sand filter consists of a suitably retained bed of sand resting upon a gravel base and provided with inlet and eflluent means, so that water supplied thereto and standing thereon will descend in the process of filtration directly downward through the sand body and gravel base. The water is supplied with a coagulant, and that with the impurities extracted therefrom soon forms a coating on the top of the sand bed which the water penetrates with difficulty, with the result that its rate of operation is increasingly slowed down so much that it soon becomes necessary to wash the sand by reversing the fiow of water therethrough.

In carrying out my method in its preferred form, I imbed in the sand a plurality of discharge members, each of a considerable cubic capacity, and having the sides thereof formed of a finernesh wire screen, preferably of a No. 35 rectangular mesh, adapted to prevent the entry of the filter sand, which is usually of a .5 millimeter size. These heads are provided with pipes extending upwardly toward the top of the water over the filter bed, and preferably terminating in funnelshaped ends to facilitate the flow of the water down through the pipes into the heads and thence through the screens, by which it is divided, as it were, into fine streams radiating horizontally, and preferably somewhat downwardly, in all directions. This gives an added filter surface over that of the ordinary filter equal to the area of the screens, which may be of a number and size so that by their addition the capacity of the filter may be doubled, or even more, over that of an ordinary filter not employing my invention. Furthermore, the sand adjacent these screen surfaces does not seem to be fouled as quickly as the surface sand, 50- that the filter can be operated for a longer time without the necessity of washing it than can the ordinary type not employing my invention.

I may also provide connections from the washwater supply to the filter members so that wash water may be driven from the heads in the same manner as the water to be filtered, butv at a greatly increased pressure so that they may be used also for washing the sand bed, and where the sand is at the same time expanded by washingit in the customary manner by wash water rising vertically therethrough with considerable velocity, I have found that the cross currents, so to speak, of wash water are very much more eflicient than when either is used alone.

To illustrate my invention, I annex hereto six sheets of drawings, in which the same reference characters are used to designate identical parts in all the figures, of which- Fig. 1 is a transverse section through a filter unit employing my invention;

Fig. 2 is a detail in vertical section, on an enlarged scale, on the line 22 of Fig. 1;

Fig. 3 is a top plan view of a portion of said unit in section on the line 33 of Fig. 1;

Fig. 4 is a perspective view of a battery of the discharge heads connected up in a preferred manner;

Fig. 5 is a side elevation of the battery shown in Fig. 4, on an enlarged scale and with one of the discharge heads in central vertical section;

Fig. 6 is a detail in section substantially on the line 6-6 of Fig. 5; I

Fig. '7 is a top plan view, partly in section, of the battery shown in Figs. 4 and 5;

Figs. 8-, 9 and 10 are a side elevation, vertical and horizontal sections of a portion of the screen, on a much enlarged scale;

Fig. 11 is a sectional view through a filter unit at right angles to the section shown in Fig. 1, with a modification of the connections to the discharge heads which permits their use in washing the filter sand;

Fig. 12 is an enlarged detail in section on the line l2l2 of Fig. 11;

Fig. 13 is a view similar to Fig. 11, but showing another modification of the piping connections by which the discharge heads may be used for washing the sand; and

Fig. 14 is a top plan view, on an enlarged scale, as seen looking down into the unit shown in Fig. 13.

Referring first to Figs. 1, 2, 3, 11 and 13, the ordinary filter unit as now generally constructed consists of a concrete chamber having the bottom 20, the side walls 2| and the end walls 22. Extending along the bottom and imbedded therein are the ordinarily rectangular conduits 23 having at intervals the Ts 24 in their upper surface, from which extend the horizontal collecting pipes 25 having the perforations 26. The bottom and these pipes are covered by a suitable layer 21 of gravel, upon which is placed a layer of filter sand. Extending along the units are channels 29 through which the water to be filtered is supplied, and these channels have apertures 30 through the walls 2 l, which apertures are connected with the spillway troughs 3! extending across the units, and serving to bring the water to the sand during the process of filtration, and to carry off the dirty water during the reverse washing operation. The conduits 23 have the short pipes 32 opening thereinto at intervals, which pipes are connected, as seen in Fig. 1, to the main pipes 33, which serve to carry off the filtered water during the filtration process, and to deliver the wash water during the reverse flow necessitated by the washing process. The structure so far described represents an ordinary filtration plant, and, per se, forms no part of my invention.

Referring now particularly to Figs. 5 and '7, I preferably construct the top of each discharge head of a substantially conical shaped casting 34, preferably having four ears 35 on the top thereof and preferably internally threaded to accommodate-the connections 36 shown as screwed therein. It also has the spider 37 on its under side, through which passes the screw bolt 38 which connects it with a similar web 39 in the top of the bottom casting 10, which preferably has the four ears 5! and the pair of apertures 42 into which the plugs 43 are screwed, so that they can be removed for cleaning out the bottom of the head proper. The screen M is, as seen in Figs. 8, 9 and 10, of a rather elongated rectangular mesh and of a dimension that prevents the passage of the filter sand therethrough. As seen, it is preferably the shape of an inverted, hollow truncated cone, and is clamped at its ends between the top piece 34 and the bottom piece 40 by the screw bolt 38. The structure is preferably strengthened by the bars 45 bolted to the ears 35 and 4!, as clearly seen in Fig. 5. Where these heads are connected in batteries of four, as I prefer, the top pieces are preferably connected by the brace bars 46 bolted to the ears 35, as best seen in Fig. 4. The bottom pieces 35 preferably have the downwardly extending legs 47 which have at their bottoms the horizontally extending flanges 48, which cooperating with the similar flanges on the jaws 49 are adapted to secure the legs by the-bolts 50 to the horizontal webs 5! of the preferably rectangular base piece 52, which may be of the shape clearly shown in Figs. 4 and 7, and which rests on the top of the gravel layer 27. The connections 36 have the elbows 53 on their upper ends, and these are connected by suitable pipe sections and nuts with the Ts 54, which in turn are connected by the check-valve casings 55, best seen in Fig. 6, with the central T 56, which is threaded on the bottom of the vertical pipe 57, extending upwardly, as seen in Figs. 1 and 11, and terminating in the funnel-shaped enlargements 58, which preferably extends slightly above the tops of the troughs 30 and below the bottom of the openings 59 in the walls 2 l, which openings limit the height of the water that can stand on the sand.

The operation of the apparatus as thus far described will be readily apparent, as during the filtration, the water flowing down through the pipes 5'! passes the check valves 6!) in the casings freely and is discharged at a rate depending on the head, through the screens, and horizontally and slightly downwardly, with the result that a filtering surface equal to the area of the screens is added to that of the ordinary construction. When it becomes necessary to wash the sand, the flow is reversed, and the sand is washed in the customary manner as in the ordinary filter, but the wash water does not enter the discharge heads because the check valves 50 prevent its upward movement therethrough.

In Figs. 11 and 12, I have shown a modification in which a wash water pipe 5!, preferably controlled by a hydraulic valve 52, carries a series of downwardly extending branches 63 to each of two batteries of the discharge heads, and at its bottom terminates in a T 64 having the horizontal pipe 55 extending therefrom to the Ts 55, which in turn are connected by the two pipes 61 with the Ts 68, which in turn are connected by the pipes and nuts 59 with the apertures 42, best shown in Fig. 5, in the bottom pieces 4!), so that with this arrangement, when the valve 62 is opened, the wash water can pass upwardly into the discharge heads and out through the screen surface to wash the sand, in this case rising and passing oif through the troughs 3!. This furnishes an additional and very efficient washing action not only for the sand fouled by the discharge heads, but for the surface sand.

In Figs. 13 and 14, I have shown a further modification of the structure shown in Figs. 11 and 12, in which the pipes 53 have connections to the top pieces 34 of the discharge heads, similar to the connections between the pipes 51 and saidheads as shown in connection with the form shown in Figs. 1 to 5. Each of the pipes 63-"-, however, has in it a T 10 which, through the check valve H, is connected to the elbow 12, from which extends upwardly the vertical pipe 51 which terminates at the same level as the pipes 51. With this construction, when the apparatus is used for filtration, the valve 62 is closed and the water to be filtered enters through the troughs 3!, as before, and reaches the discharge heads through the pipes 51 and the bottom of the pipe 63 the check valve 7! permitting its free flow in this direction. When the filter bed is to be washed, the valve 62 is opened, and the water descends through the pipe 63 to the discharge heads and passes into the sand and up to the troughs 35, as before, the check valves 1 I in this case, preventing the discharge through the pipes 51 While I may wash the sand through the heads or members alone, as described in connection with the structures shown in Figs. 11 to 14, I

preferably employ simultaneously therewith the I regular washing system provided by reversing the flow through the efiiuent means shown in Figs. 1 and 2, as I have found by experience that a very superior result is obtained when both washing means are employed simultaneously as compared with either separately. As I preferably wash the sand, the pressure of the Water rising vertically through the sand is only sumcient to expand the sand, i. e., lift it so that it becomes somewhat fluid as it were in its action, but not enough to stir it up as much as is now deemed necessary to get the best washing action, as heretofore practiced. The jets of water under considerable pressure moving laterally and slightly downwardly from the heads impinging against this expanded sand sets the grains in horizontal and radial movement from around each head, with the result that the grains meeting those from the surrounding heads moving in opposite and diiferent directions grind against each other, producing a herein claim said methods, but have claimedsaid methods, together with certain specific apparatus for carrying them out, in my application Serial No. 121,676, filed January 21, 1937.

While I have herein shown and described certain specific forms of apparatus, I do not desire to be limited in the interpretation of the claims therefor, except as may be necessitated by the state of the prior art.

What I claim as new, and desire to secure by Letters Patent of the United States, is:

1. In a filter, the combination with a bed of loose filtering material provided with retaining means and inlet and eiiiuent means, said retain ing means including a permeable layer on which it rests, of a discharge member in the bed through which the water is discharged, piping to the member for supplying water thereto, and means resting on the permeable layer for supporting the discharge member above the permeable layer and beneath the surface of the bed.

2. In a filter, the combination with a bed of loose filtering material provided with retaining means and inlet and efiluent means, of a discharge member embedded therein through which the water is discharged, piping to the member for supplying water thereto, a valve in said piping to prevent movement of the water ther-ethrough during the washing of the bed, and piping connected to said member to pass wash water therethrough.

3. In a filterQthe combination with a bed of loose filtering material provided with retaining means and inlet and effluent means, of a discharge member embedded therein through which the water is discharged, piping connected to the top of the member for supplying water thereto, a valve in said piping to prevent movement of water therethrough during the washing of the bed, and piping connected to the bottom of the member to pass wash water therethrough.

4. In a filter, the combination with a bed of loose filtering material provided with retaining means and inlet and efiluent means, of a discharge member embedded therein through which the water is discharged, piping to the member through which wash water may be supplied, an inlet branch pipe extending upwardly and terminating in an open end slightly below the level at which the water stands during the operation of the filter, and a check valve between the piping and the branch pipe to prevent wash water flowing through the inlet pipe.

5. In a filter, the combination with a bed of loose filtering material provided with retaining means and inlet and efliuent means, said retaining means including a permeable layer on which it rests, of a plurality of discharge heads, each head consisting of a top casting having a pipe connection thereto terminating above the bed, a bottom casting, a fine-mesh screen held between the two castings, means for securing the two castings together to hold thescreen in place, a leg extending downward from the bottom casting, piping to each of the heads for supplying wash water thereto, a supply of wash water connected to said piping, a base member adapted to rest on the permeable layer, and means for clamping the legs to the base member.

6. In a sand filter, the combination with a sand bed ofloose filtering material provided with retaining means and inlet and efiiuent means, said retaining means including a permeable layer ,on which it rests, of a plurality of discharge heads, each head consisting of a top casting having a pipe connection thereto, a bottom casting, a fine-mesh screen held between the two castings, means for securing the two castings together to hold the screen in place, a leg extending downward from the bottom casting, piping to each of the heads for supplying water thereto, a base member adapted to rest on the permeable layer, means for clamping the legs to the base member, and brace bars connecting the top castings.

7. In a large gravity filter open to the atmosphere, the combination with a chamber, of a bed of loose filtering material therein partially filling the same and confined only at its sides and bottom, efliuent means in the bottom of the chamber adapted either to carry oft; filtered water from the bed or to supply wash water rising therethrough throughout its entire area, piping connected to said efiluent means to deliver the filtered water therefrom or carry the wash water thereto, troughs extending at intervals across the chamber well above the surface of the bed and adapted either to allow water to be filtered to overflow therefrom onto the entire surface or the bed or to allow wash water rising through the bed to spill thereinto and be carried ofi thereby, hollow discharge members which the water to be filtered or supplemental wash water enters, located in the material throughout a horizontal plane of the bed and adapted to permit Water to be discharged therefrom either for filtering or washing the material in said planebeneath the surface of the bed, screens through which the water is discharged constituting a portion of side walls of the discharge members to prevent the filtering material from entering said members, piping connecting inlets of said discharge members with a supply of washwater under pressure, means for admit ting water to be filter-ed to the surface of the bed, valve mechanism to control the admission of the supplemental wash water to the discharge members, and means permitting some of the water to.

be filtered to flow by gravity from over the surface of the bed into the discharge members, and thence out through the screens'when the valve mechanism controlling the supplemental wash water is closed.

IRA H. JEWELL-

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