USRE21652E - Method and apparatus for - Google Patents

Description

Dec. 3, I p M THAYER Re. 21,652.

METHOD AND APPARATUS FOR FILTERING SEWAGE Original Filed May 27, 1936 2 Sheets-Sheet. 1

' INVENTOR. Y B402 M 504%? 42a flzuz ak I ATTORNEY.

1940- P. M. THAYER I Rs. 21,652

METHOD AND APPARATUS FOR FILTERING SEWAqm Original Filed May 27 1956 2 Sheets-Sheet 2 Reissues! Dec. 3, 194i) METHOD AN D APPARATUS FOR. FILTERING SEWAGE Paul M. Thayer, Milwaukee, Wis.

Original No. 2,065,836, dated December 29, 1936, serial No. 81,977, May 27, 1936. Application for reissue December 24, 1938, Serial No. 247,722

11 Claims.

This invention relates to a method and apparatus for filtering sewage.

Though the invention is not confined to a continuous process or an apparatus for continuous filtering of sewage, it is nevertheless eminently adapted for such operation, and an object of this invention, therefore, is to provide a method and an apparatus for the continuous filtration of sewage.

In filtering sewage various means have been employed, such as providing a settling tank and filtering means through which the sewage passes, and attempts have been made to clean the filtering means'while the apparatus is in operation, but these attempts have not proven wholly satisfactory for several reasons, among which may be mentioned the fact that during this cleaning operation a considerable quantity of ,dirty liquid passes into the clear liquid stream and also a large percent of the filtering material is lost and the device rendered less effective as I its time of use increases.

Also difllculty has been experienced due to the fact that a very large amount of power is consumed in these cleaning operations in certain forms of the heretofore known types of sewage filter cleaning means.

' Further objects of this invention are to provide an apparatus for filtering sewage which overcomes the above noted defects, which is so made that it will continuously filter the sewage and also, if desired, continuously clean the filtering means without causing the dirty liquid to fiow outwardly with the clear liquid but confining the dirty liquid to the settling tank and preventing its outward flow with the clear liquid, and in which the cleaning action may be intermittent if desired or may go on continuously and may take place progressively, that is to say, the cleaning means may progress along the filtering means and may confine its zone of operation to a restricted area thereof, leaving the major portion of the filtering means undisturbed and active for the continuous operation of the filtering apparatus.

A particular object of this invention is to provide a. novel apparatus and a novel method of sewage filtration which contemplates the proume stream of clear liquid, confining the cleaning action to a limited progressing zone-ofv the filtering means, and confining the disturbance and agitation oi the sewage below the filtering means to a very small area far remote from the sedimentation zone so that the settling action of the sewage is notin the least interfered with and so that the normal operation of the apparatus is undisturbed, thereby permitting the continuous operation of the machine while the cleaning action is taking place.

In greater detail, objects of this invention are to provide a sewage filtering apparatus in which a settling tank is provided with a sedimentation zone in the lower portion thereof, in which filtering means are (provided at a convenient point in the tank, for instance adjacent the margin or margins thereof, in which by means of a differential level or pressure the sewage passes up- .wardl-y through the filtering means, in which even the very fine solid material, such as the colloidal material, may ,adhere to the under side of the filtering means and may form clusters or groups or aggregates whose mass is constantly augmented by oncoming, minute or colloidal solids until finally these clusters either break away and drop of their own weight or are dislodged by the cleanlng means and settle to the bottom of the tank without getting the opportunity, even during cleaning, of passing upwardly through the filtering means, and to' provide 1 a cleaning apparatus which utilizes only the clear liquid above the filtering means and passes this clear liquid down at a low velocity and high volume.

Further objects are to provide a cleaning device ter a sewage filter which is adapted to travel continuously along and .above the filtering means, which draws clear liquid from above the filtering means and discharges it downwardly, preferably entraining a large volume of other clear liquid so that a low velocity high volume stream of liquid is passed downwardly through the filtering means, thereby dislodging adhering solids from the under side of the filtering means.

Further objects are to provide a cleaning device ter a sewage filter in which the filtering means, if desired, maybe made sufllciently flexible so that it is slightly bowed downwardly or manipulated during the cleaning operation and by the downwardly fiowing large volume of clear liquid, thus assisting in dislodging adhering ma-' terials and removing any materials that may be held in the interstices of the filtering means.

- means and pump or force it downwardly with a relatively low velocity and high volume through the filtering means, and in which the apparatus issomadethatthedischargemaybe adjusted bothastovelocltyandvolume.

' I5 and II.

Further objects are to provide a filtering apparatus for sewage which may be made very cheap y, inwhich the parts which are likely to become worn during use may be cheaply and readily replaced, andin which the initial installation may be ma e at a comparatively small cost.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a fragmentary vertical sectional view of a sewage filtering apparatus.

Figure 2 is a fragmentary plan view of a portion of the filtering means, with parts broken away, showing the cleaning apparatus in position.

Figure 3 is a vertical elevation, partly in section and with parts broken away, showing the cleaning device, such view corresponding to a section on the line 3-3 of Figure 2.

Figure tie a sectional view on the line H of Figure 3.

F gure 5, shows a modified form of the device.

Referring to the drawings, it will be seen that a settling tank I has been provided which may be formed in any desired shape, for example circular, and may be provided with concrete side walls 2 and a concrete bottom I. The incoming sewage may be delivered through an inlet pipe or pipes 4 which has an upwardly turned end I fordischarging hesewageintoastillingwellt defined ,by an annular downwardly extending baiiie "I. A clear liquid launder 8 may receive the discharged clear liquid and a suitable pipe or pipes I may be provided for carrying off the clear filtered liquid. The clear liquid launder I or clear liquid receiving channel may be formed between an upstanding outer wall ll of the main concrete side walls and an inner weir or overflow bailie H which may be formed, if desired, of sheet metal. An annular wall I! may be provided and may also be formed of sheet metal and preferably ex-v tends downwardly to a point below the lower edge of the stilling well wall I, as shown in Figure 1. Suitable brackets I! may be provided atintervals to support the member l2. I

The filtering means is indicated at It and may be a cloth or wire screen, as shown in Figure '2, and is preferably formed of removablesections. This filtering means is carriedin any suitable way, as for example, upon the annular angle irons Additional stiffness for the structure may be afforded by providing transverse struts l1,seeFlgure2,atregular-interva1s.

Thelowerportimiofthesettlingtank I constitutes a sedimentation none and preferably the bottom 3 thereof is slanted inwardly to. a centrally located sump II. If desired, a power driven scraper consisting of a spider frame II with scrapers 20 may be carried in any suitable man-- ner,-as from a centrally located shaft 2!, and is designed to scrape the sediment or sludge at the ,bottomofthetankandcauseittograduallypass into the sump it, from which it is withdrawn or discharged by means of the sludge pipe 22. Any

suitable means, for example the motor 23, see Figure l, and suitable reduction mechanism may be provided for driving the sludge scraper.

The settling tank provides a large, quiet area for the gradual settling of the solid material downwardly from the sewage. However, there is a quantity of solid material that is suspended in the liquid and as the liquid passes upwardly, this suspended solid material, even if of colloidal form, is arrested or clings to the lower side of the filtering means l4 and the clarified or clear liquid flows upwardly through the filtering means and overflows into the clear liquid launder or dis-, charge channel 8.

It has been found that even if the suspended material is of colloidal form, that it will adhere to the screen or filtering means and will form clusters or aggregates of gradually increasing size which will, either by their own weight or from the cleaning means hereinafter described, dislodge and fall from the under side of the filtering means and settle to the bottom of the tank In order to prevent clogging of the filtering means and to provide for the ready cleaning thereof and the continuous uninterrupted operation of the sewage filter, a novel form of cleaning means has been provided which is so made that it does not cause agitation in'the sedimentation zone, but in which the washing or cleaning of the filtering means is confined to a very small section or none closely adjacent the filtering means and extends downwardly beyond the filtering means only a very limited distance, the sedimentation none being remote or spaced a great distance downwardly therefrom so that there is no interference in the settling out of the solid material during the cleaning or washing of the filtering means.

The washing device may include a framework or body portion formed of a central I-beam or other structural member 24 provided with inner and outer end portions 25 and 20. These end,

member 35,, which is of rectangular boxlike shape, may be supported from the intake pipe 34 of the pump 38. An electric motor Il may be directly coupled to thepump, as indicated in Figure 3, and the motor, pump and header 3! may be supported from the travelling carriage structure.

The lower portionof the header I2 is only-partially closed by means of thebottom plate 31, a

slot I. being provided between a marginal edge of the channellike bottom plate 31 and the adja- -scoop 35. If desired, the scoop or skimming cent wall of the header 3:. This bottom plate 31 in reality constimtes a spreader plate to secure a uniform fiow of the liquid downwardly through the nozzle portion SI of the device, a baille ll be- ,ing preferably provided within the header to assist in securing a distributed and uniform fiow of liquid downwardly from the header.

The nomle portion I! is formed by extending the inner wall 4| of the header downwardly and 7| by extending the outer wall 42 thereof downwardly and preferably on a slant towards the inner wall 4|. In forming the device, it is preferable to make the wall 42 of lighter material. than 5 the wall 4| so that it may be flexed to increase or decrease the size or width of the nozzle 33.

The nozzle 39 supports a forward and a rear plate 43 and 44 and these plates, as well as the nozzle, extend transversely across the filtering means, as shown most clearly in Figures 1, 2 and 3. Any suitable means may be provided for adjustably holding the nozzle and the plates. For example, a plurality of bolts 45 may be positioned at regular intervals and passed through: tlre nozzle and the plates 43 and 44. Spacers 46 are provided between the plate 43 and the wall 4| and spacers 41 are provided between the plate 44 and the lower or nozzle portion of the wall 42. Nuts are carried by the bolts 45, as shown, and bear against the plates 43 and 44 and the walls 4| and 42.

It is obvious that the opening or width of the slot of the nozzle 39 may be varied by backing the nuts bearing against the wall 42 and the plate 44 outwardly to increase the size of the nozzle, or moving them inwardly to decrease the size of the nozzle. Also the size of the spacers 41 or the size of both the groups of spacers 45 and 41 may be varied to vary the spacing of the plates 4-3 and 44 from the nozzle.

It will be observed from an examination 0 Figure 3, that the nozzle and plates 43 and 44 constitute an injectorso that the downwardly projected stream of liquid from the. nozzle entrains a large volume of liquid between the plates 43 and 44 and projects this large volume low velocity stream of liquid downwardly against and through the filtering means or screen l4, thus cleaning the screen and dislodging adhering material from the screen. As indicated by the arrows in Figure 3, the disturbance or agitation is confined to a very limited or restricted area immediately adjacent and below the screen and this disturbed area is far remote from the sedimen- 45 tationzone and is confined at any instant to a limited area of the filtering means or screen. Consequently there is no interference whatsoever to the free and undisturbed settling of solid material or to the continuous operation of the filter as by far the major portion of the screen section is wholly clear and free of the cleaning device.

As the cleaning device progresses forwardly in 65 the direction of the arrow, see Figure 3, the clear liquid is scooped up or drawn into the scoop or skimmer 35 from adjacent the top surface of the clear liquid, the liquid level above the filtering means being indicated in Figure 3, and the 00 low velocity large volume stream of clear liquid is projected downwardly through the screen. The device progresses forwardly continuously around the filter and thereby continuously cleans the screen without interfering with the continu- 65 ous operation of the sewage filter.

It is to be noted, as indicated in Figure 3, that the screen may be sufliciently flexible so that it will be slightly bowed or distorted downwardly, as shown in dotted lines in such figure, while it 70 isacted upon by the low-velocity large volume stream of clear liquid and consequently this working or motion of the screen while the clear liquid'is passing through the bowed section willassist in dislodging any adhering material that may either cling to the under side of the screen or have found its way into the interstices of the screen.

The electric motors 3| and 36, see Figure 1, may be supplied with. current from rails 48, as shown, or any other suitable means to provide power for the motors carried on the travelling cleaning device.

It will be seen that there is no possibility of the discharge of unfiltered sewage along with the clear liquid during the washing operation and it will be seen further that the washing operation may be either continuous or intermittent as desired.

Obviously the invention is not confined to a circular tank, butmay be employed where the settling tank is of rectangular or other shapes. For example, as indicated in Figure 5, a rectangular tank 49 may be provided, the filtering section being indicated at 50 and the clear liquid launder at ii, the inlet and outlet pipes being indicated at 62 and 53. The washing device is not shown in this view, but is adapted to travel back and forth over the filtering zone 50, as is apparent from the preceding description.

It will be seen that a novel sewage filtering apparatus and a novel method of filtering and cleaning has been provided by this invention whereby a continuous operation of the filtering apparatus may be had and at the 'same time either continuous or intermittent cleaning of the filtering means or screen may be secured by a powerdriven automatic cleaning apparatus without in any way disturbing the gradual settling of the'solid material normally taking place in the settling tank of the filter.

It will be seen further that the device may be constructed very cheaply and that a very inexpensive filtering means maybe used, either cloth or wire screen, or any other suitable material, and that means are provided which preclude the clogging of the filtering means.

It will be seen further that the initial cost of the filtering apparatus is relatively small and that the cost of operation of the cleaning device is negligible as two relatively small motors are all that is required to operate the cleaning apparatus for the filtering means. Consequently, the consumption of power is extremely small for the cleaning operation.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. A filtering device having a main settling chamber and having an overflow weir and having a zone of filtering material suspended horizontally within the settling chamber adjacent the weir and through which the liquid to be filtered is adapted to pass in an upward direction. washing means movable along the filtering material and including power means for forcing liquid through the filtering material in the reverse direction from that normally travelled by 65 said liquid, said washing. means operating on successive sections of the filtering material and allowing continuous and uninterrupted operation of the filtering device, the solid removed material dislodged from the bottom of the filtering material falling back into the settling chamber.

, 2. A filtering device having a main settling chamber and having an overflow weir and having a zone of filtering material located horizonwithinthesettlingchamberadjacenttho andthroughwhich filtering device, the solid removed material dislodged from the bottom of'the filtering material falling back into the settling chamber.

3. A filtering device having a main settling chamber and having a zone of filtering material A suspended horizontally within the settling chamber and through which the liquid to be filtered is adapted to pass in an upward direction, means for temporarily collecting clear liquid after it has passed upwardly through the filtering material, washing means movable along the filteringmaterial and including power means having an intake for the clear liquid, said washing means forcing the clear liquid through the filtering material in the reverse direction from that normally travelled by said liquid, said washing means operating on successive sections of the filtering material, the solid removed material dislodged from the bottom of the filtering rnaterialfalling back into the settling chamber.

4.Afiltering devicehavingamain settling chamber and having an overflow weir and having a zone of filtering material suspended horizontally within the settling chamber adjacent the overflow weir and through which the liquid tobefilteredisadaptedtopassinanupward direction, washing means located above and 4 movable along the filtering material and including power means for drawing clear liquid from above the filtering material and for forcing the said clear liquid downwardly through the filtering material, said washing means including 45 means for entraining additional 'clear liquid from above the filtering material adjacent the discharge portion of said washing means to produce a large volume low velocity downwardly projected stream of clear liquid. through said filtering material, said washing means operating on successive sections of the filtering mate-. rial and allowing continuous and uninterrupted operation of the filtering device, whereby any agitation below the filtering material is confined to a shallow zone located closely adjacent the lower side of the filtering material, the solid removed material dislodged from the bottom of no 5. a filtering device having r main settling the filtering material falling back intorthe set-" tling chamber.

chamber and having an overflow weirand having a zone of filtering material suspended within the settling chamber adjacent the overflow weir and through which the liquid to be filtered is adapted to pass to said overflow weir, washing means movable along the filtering material and including power means for drawing clear liquid from the overflow side of the filtering mater'ial and for forcing the said clear liquid through the filtering material in the reverse direction to the normal flow through the filtering material, said washing means producing a large volume low velocity stream of clear liquid through said filtering material, said washing means operating onsuccessive sectionsotthofiltsring naterisl and allowing continuous and uninterrupted operation of the filtering device, whereby any agitation on the inner side of 'theflltering material is confined to asrnall zone located closely adjacent the inner side of the filtering material,

the solid removed material dislodged from the filtering material passing immediately from the small agitated zone into an extensive quiet zone.

6.Awashingmeansiorwashingthefiltering material of a filter while said filter is inoperation, said washing means comprising power driven means for drawing clear liquid from one side of the filtering material and for forcing clear liquid through thesfiltering material towards the other side of the filtering material, said washing means having a discharge portion located adjacent the filtering material and having an injector carried adjacent thedischarge portion of the washing means, said injector having an intake for clear liquid located at a point spaced from the filtering material.

7. A washing means for washing the filtering material of a filter while said filter'is in operation, said washing means comprising power driven means for drawing clear liquid from one side of the filtering material and for forcing clear liquid through the filtering material towards the other side of the filtering material,

said washing means having a discharge portion spaced from the filtering material and having an intake for entraining liquid, said injector having an adjustable member to vary the intake opening for the entrained liquid.

. 8. Washing means for a filter having extended filtering means, said washing means comprising power driven means for drawing clear liquid from one side of said filtering means and for forcing clear" liquid through the filtering means to the other side thereof, said washing means having the intake portion thereof provided with a skimmer having an open portion directed away from the filtering means and having a discharge portion located adjacent. the filtering means, and an injector located adjacent the discharge portion of said washing means for entraining aditional clear liquid, said injector having its inlet portion located at a point spaced from said filtering means.

9. The method of continuously filtering sewage comprising passing sewage upwardly through a filtering means, allowing the solid material in the sewage to settle at a material distance below the point of filtration, discharging the clarified liquid from the upper side of the filtering means and progressively operating on successive sections of the filtering means by passing a low velocity relatively high volume flow of the filvtered liquid downwardly through the filtering means movable along the filtering material and including power means for drawing clear liquid from the overflow side of the filtering material and for causing a part of the said clear liquid to fiow through the filtering material in the reverse direction to the normal fiow through the filtering material, said washing means producing a large volume low velocity stream of clear liquid through said filtering material, said washing means operating on successive sections 01 the,

5 ll. 'lhe method of continuously filtering sewage comprising passing sewage through a filtering means, allowing the solidmaterial in the sewage to settle at a distance from the point of filtration; discharging the clarified liquid from one side of the filtering means and progresively operating on successive sections of the filtering means by passing a low velocity high volume flow oi the filtered liquid backwardly through the filtering means to dislodge adhering material from the slide of the filtering means which is normally upstream without causing agitation of the sedimentation and by conducting the dislodged sedimentation to the settlement area without agitation sufilcient to break up the flocks oi sedimentation as removed irom the filtering means.

PAUL Ni. THAY'ER.

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