US2416867A - Combined sewage settling and digesting tank having an inclined apron discharging into the tank, an effluent channel, and an inverted v-shaped baffle extending across the tank between the apron and the channel - Google Patents

Description

March 4, 1947. c, CQBERLY 2,416,867

COMBINED SEWAGE SETTLING AND DIGESTING TANK HAVING AN INCLINED APRON DISCHARGING INTO THE TANK, AN EFFLUENT CHANNEL, AND AN INVER'I'ED V-SHAPEDHBAFFLE EXTENDING ACROSS THE TANK BETWEEN THE'APRCN AND THE CHANNEL Filed Sept. 6, 1943 I mvmon TTORNEY.

Patented Mar. 4, 1947 COMBINED SEWAGE SETTLING AND DI- GESTENG TANK HAVING AN INCLINED APRGN DISCHARGING INTO THE TANK, AN EFFLUENT CHANNEL, AND AN IN- VERTED V-SHAPED RAFFLE EXTENDING ACROSS THE TANK BETWEEN THE APRON AND THE CHANNEL Carroll H. Coberly, Denver, 0010.

Application September 6, 1943, Serial No. 501,441

Claims.

This invention relates to a combined settling and digesting tank for sewage, and has for its principal object the provision of a device of this character which will be of exceedingly high efficiency in the clarification of sewage; which will be continuous in its operation; and which will be economic to construct and operate.

Another object of the invention is to provide a proportioning baflle for the influent so-shaped that it will uniformly distribute the incoming solution throughout the entire width of the settling ta nk so that all portions thereof will have uniform treatment time and the formation of eddy currents, short circuits, etc., will be avoided.

A further object is to provide a device of this character in which the settlement of solids will be substantially uniform throughout the entire horizontal cross section of the tank so as to avoid piling at the influent side and the necessity for reverse flows.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and efficiency. These will become more apparent from the following description.

In the following detailed description of the invention reference is had to the accompanying drawing which forms a part hereof. Like numerals refer to like parts in all views of the drawing and. throughout the description.

In the drawing:

Fig. 1 is a plan view of the invention applied to two treatment tanks placed in parallel relation;

Fig. 2 is a cross section through a typical tank, taken on the line 2-2, Fig. 1; and

Fig. 3 is .a detail section, taken on the line 3-3,

Fig. 1, illustrating the improved proportioning The invention comprises a substantially cubical tank it provided with an inclined iniiuent apron along the full width of one side thereof. The sides of the influent apron converge to a medial apex where the infiuent is received from an infiuent channel #2. The bottom of the influent channel is positioned substantially at the water line of the tank iii. A baflle plate 53 of unusual design is positioned at right angles to the axis of the channel l2 at a point adjacent the greatest width of the influent apron II.

A horizontal, triangular gas deflecting ridge M, is formed along the inner wall of the tank ii] immediately below the delivery lip of the apron' H. A bafile member, 15, of triangular cross section, extends horizontally across the tank 10 par- 2 allel to the delivery lip of the apron H. The triangular baffle, has of course, three relatively sharp edges indicated by the numerals I6, I! and Hi. The edge !5 is positioned above the ridge It closely adjacent the front wall of the tank so that it will be impossible for gas bubbles rising vertically to pass between the edge It and the ridge i l.

The lower surface of the baflle between the edges it and i3 is inclined upwardly toward the rear to deflect gas bubbles toward the edge IS. The front surface of the baflle between the edges l6 and i 'l is inclined upwardly toward the rear at an angle exceeding 50 terminating at the edge it which is positioned at a relatively sha low depth below the waterline. The rear surface of the triangular baffle inclines rearwardly and downwardly at an angle of approximately 45 to the rear edge i8.

An inclined partition It extends from the top of the tank forwardly and downwardly at an angle of approximately The partition I9 is placed parallel to the triangular balile l5 and the lower edge of the partition is positioned forwardly of the edge I 8 and above the rear surface of the triangular bafile.

The upper extremity of the wall I9 is bridged to the rear wall of the tank by means of a gas cover 29 through which a suitable gas line 2| communicates. An effluent channel 22v extends across the top of the tank parallel to the rear wall thereof. This channel is formed with a high front board 23 which prevents the influent from flowing into the channel and with a relatively low back board 24 the upper edge of which determines the solution level in the tank. The channel 22 is positioned closely adjacent the inclined wall l9 .so as to leave a relatively narrow upflow throat 25 therebetween.

The bottom of the tank I 0 is depressed to form a collection hopper 26 terminating at the middle of the tank in a sump 21. A lift pipe 28, with which a draw-off pipe 29 communicates, extends to the top of the tank where it is closed by means of a suitable cap 30 which provides convenient access for cleaning purposes.

The above description relates to but a single tank, In the usual construction, a plurality of similar tanks will be employed, as shown in Fig. 1. When more than one tank is used, it is essential for the efiicient operation that all tanks receive exactly the same flow. This is accomplished in the present invention by leading the influent channels 12 from a valve box 3i. A flexible valve blade 32 extends from a fixed point between the channels l2 forwardly to a position opposite a tion which slidably engages the sides of the blade 32. This construction provides a very accurate control of the flow to two tanks so that both will be fed at exactly the same rate.

To obtain perfect and uniform settling in each tank it is absolutely essential that the velocity and distribution of flow across the bank be uniform at all points. To obtain this uniform flow from a relatively narrow incoming channel at the middle of one side presents quite a problem. This problem has been solved in the present inven--' tion, however, by the specific shape of the bafile I3. It was found that the depth of this bafile at all points throughout its length must be in exact proportion to both the energy gradient of the tank and the kinetic energy of the incoming solution at that point. The baflle was first proportioned so that its widest point was at the point of greatest velocity, and its narrowest points were at the points of least velocity, the intermediate curve approximating a parabola. This was not found to be entirely satisfactory, however, due to the fact that the distance from the point of delivery of the influent to the bafiie I at the middle was much less than the distance to the baffle at the sides. In other words, it was necessary to modify the velocity or kinetic energy curve in proportion to the energy gradients of the tank in order to obtain a uniform settling interval at all points. The resulting baffie has somewhat the appearance shown in Fig. 3, having its deep est point opposite the delivery of the influent channel I2 and extending above the waterlevel at its extremities, the bottom edge being curved so that at any. point the depth is proportional to the energy gradient and the kinetic energy of the solution at that point. This design results in an absolutely uniform distribution of flow across the tank from the baffle I3 to the effluent channel 22.

The incoming solution flows from the apex of the apron II across each tank and overflows the back board 24 of the effluent channel 22. Upon entering the apron the velocity of flow is quickly reduced, resulting in immediate settling of a portion of the solids on the apron I I. Since the incoming'solution is forced downwardly at this point by the action of the baffle I3 the solids are washed down the apron into the passage between the ridge I4 and the edge I6.

A portion of the remainder of the suspended solids will be carried against the front wall of the triangular baiile where their forward movement will be stopped. These solids will gravitate down 7 the inclined front wall against the current which is rising at this point to flow over the edge Il. The descending solids entrap additional solids in the rising solution creating a continuous descending flocculation which exerts a constant straining action on the solution in front of the inclined.

front wall of the baiile I5 so that by far the major portion of the solids will pass downwardly in a continuous curtain between the ridge I4 and the edge I6. 7

v The above action is repeated as solution flows from the edge I! to the channel 22 so that any remaining solids are removed in this second trap area. In the latter area the solution is again caused to flow downwardly over the rear surface of the baffle I5 to sweep accumulated solids down- The shaft suspended solids which fall from the entire length of the edge I8 to the bottom of thetank.

It can be seen therefore, that that portion of the tank above the baffle I5 and the wall I9 forms a highly efficient settling chamber from which the solids are continuously removed and in which no gas flotation is encountered.

The portion of the tank below the settling chamber forms an effective digestion chamber. The major portion of the solids enter the forward portion of this chamber throughout its width from the ridge I4. The gases however forming in the accumulated sludge continuously lifts parti cles thereof. The rising particles strike the upwardly and rearwardly inclined bottom surfaces of the ridge I4, the baffle I5 and the partition I9 and are deflected rearwardly in the tank where they again settle uniformly throughout the entire area of the chamber so that there is no formation of any excess accumulation at any point. All solids eventually gravitate to the sump 2! from which they are removed as desired through the draw off pipe 29. Due to the overhang of the edge I8 and the ridge I4 no gas bubbles or gas buoyant material can rise into the settling portion of the tank to interfere with the settling therein.

While the invention has been described as particularly applicable to the treatment of sewage, it is, of course, not limited to this particular use as it will also be found valuable for the clarification of aqueous solutions of any nature.

While a specific form of the improvement has been described and illustrated herein, it is desired to bejunderstood that the same may be varied, within the scope of theappended claims, without departing from the spirit of the invention.

Having thus described the invention, what is claimed and desired secured by Letters Patent 15:

l. A combined settling and digesting tank for sewage comprising: a tank of substantially recapron; an eiiluent channel'extending acros said tank parallel to said side wall; a front board along the side of said channel facing said apron and extending above the infiuent channel; a backboardalong the opposite side of said eflluent channel terminating below said influent channel and determining the solution line in said tank; a bottom board in said channel extendingbetween and sealed to said front and back boards; I and a .bafile extending across the dischargeof said apron adjacent the greatest width thereof and at right angles to the incoming flow, the lower edge of said baiile being'curved and having its greatest depth at its middle oppositethe infiuent channel and its shallowest depth at the extremities furthest removed from the infiuent channel, the discharge of said infiuent apron being positioned substantially at said solution line.

2. A combined settling and digesting tank for sewage comprising: a tank or substantially rectangular plan; an inclined i-nfiuent apron discharging to said tank throughout substantially the entire width of the latter, said apron being reduced in width to a medial apex as it recedes from said tank; an influent channel feeding said tank at the apex of said apron; an ellluent channel extending across said tank substantially on a level with the apex of said apron and determinin the solution line in said tank; a bafile extending across the discharge of said apron adjacent the greatest width thereof and at right angles to the incoming flow, the lower edge of said baflle being curved to vary the vertical depth of said bafile. said depth decreasing as the angular distance from the apex of said apron increases.

3. A combined settling and digesting tank for sewage comprising: a tank of substantially rectangular plan; an inclined influent apron discharging to said tank throughout substantially the entire length of the front wall of the latter, said apron being reduced in width to a medial apex as it recedes from said tank; an influent channel feeding said tank at the apex of said apron; an eilluent channel extending across said tank parallel to said front wall and determining the solution line in said tank, the discharge of said apron being positioned substantially at said solution line; an inverted V -shaped baffle extending across said tank between said apron and said effluent channel and inclining downward toward the front and rear walls of said tank in closely spaced relation to the former; gas bafiling means for preventing rising gas bubbles from passing between the forward wall of said tank and said V-shaped bafile; means for passing said bubbles toward the rear wall of said tank; a gas tight cover extending over said tank from said rear wall; a partition extending downwardly from said cover below said solution line, said cover and said partition forming a gas collecting chamber above the solution line adjacent said rear wall for collecting said gas; and a gas outlet from said chamber.

4. A combined settling and digesting tank for sewage comprising: a tank of substantially rectangular plan; an inclined influent apron discharging to said tank throughout substantially the entire length of the front wall of the latter, said apron being reduced in width to a medial apex as it recedes from said tank; an influent channel feeding said tank at the apex of said apron; an effluent channel extending across said tank parallel to said front wall substantially on a level with the apex of said apron and determining the solution line in said tank; an inverted V-shaped baflle extending across said tank below and between said apron and said effluent channel and inclining downward toward said front wall and the opposite rear wall of said tank in closely spaced relation to the former; a bottom on said baffle; a ridge formed on said front wall of said tank .below and rear- Wardly of the forward edge of said baflle to deflect ascending gas bubbles against said inclined bottom, said bottom being inclined upwardly toward the rear so as to deflect the gas bubbles toward said rear wall; a gas-tight cover extending over said tank from said rear wall; a partition extending downwardly from said cover below the solution line to form a gas collecting chamber above the solution line adjacent said rear wall for collecting the gas from said bubbles; and means for conveying the gas from said chamber.

apron; an eilluent channel extending across said tank parallel to said front .wall substantially on a level with the apex of said apron and determining the solution line in said tank; an inverted V-shaped bafile extending across said tank below and between said apron and said efiluent channel and inclining downward toward said front wall and the opposite rear -wall of said tank in closely spaced relation to the former; a bottom on said baffle inclined upwardly from the forward edge to the rearward edge thereof; a horizontal ridge formed on said front wall of said tank below the forward edge of said baffle to deflect ascending gas bubbles rearwardly against said inclined bottom; an inclined partition in said tank extending from a point above and forwardly of the rearward edge of said V-shaped baffle to receive the gas bubbles therefrom and deflect them toward said rear wall; a gas collecting chamber between said partition and said rear wall to receive the bubbles from said bottom; and means for conveying the gas from said chamber.

6. A combined settling and digesting tank for sewage comprising: a tank of substantially rectangular plan; an inclined infiuent apron discharging to said tank through the front wall of said tank; an influent channel feeding sewage to said tank via said apron; an effluent channel extending across said tank parallel to said front wall; a front board on said effluent channel facing said apron and extending above said influent channel; a relatively lower backboard along said effluent channel providing an overflow to determine the solution line in said tank; a bottom board in said channel extending between and sealed to said front and back boards; an inverted V-shaped baflle extending across said tank and having its apex between said apron and said effluent channel and inclining downward toward said front wall and toward the opposite rea wall of said tank in closely spaced relation to the former; a bottom for said V-shaped baille inclined upwardly from the forward edge to the rearward edge thereof; an inclined partition in said tank parallel to said front wall and extending from a point above and forwardly of the rearward edge of the bottom of said baffle to receive the gas bubbles therefrom and deflect them toward the rear wall of said tank, said'inclined partition being closely adjacent the backboard of said effluent channel to force the fluid from said apron to take an upward course before overflowing into said effluent channel; a gas chamber between said partition and said rear wall to collect the gas from said bubbles; and means for conveying the gas from said chamber.

7 A combined settling and digesting tank for sewage comprising: a tank of substantially rectangular plan; an inclined influent apron discharging .to said tank throughout substantially the length of the front wall of the latter, said apron being reduced in width to a medial apex as it recedes from said tank; an influent chan- .nel feeding said tank at the apex of said apron; an efiluent channel extending across said tank 1 parallel to said front wall; a front board on said channel facing said apron and extending above the front wall of said tank; a backboard-alon said effluent channel providing an overflowto determine the solution line in said tank, the

discharge of said iniiuent apron being positioned l substantially at said solution line; a bottom board in said channel extending between and sealed to said front and back boards; an inverted ,V-shaped baffle extending across said tank parallel to said front wall between said apron and said effluent channel and inclining 1 downward'toward the front and rear'walls of said tank in closely spaced relation to the former; and gas baffling means for preventing rising gas bubbles from passing between the front wall of said tank and said baffle, the apex edge of said V-shaped baffle being horizontally positioned at a relatively shallow depth below the solution line of said tank.

8. A combined settling and digesting tank for tank parallel to said front wall; a front board on said channel facing said apron and extending above the front wall of said tank; a backboard along said effluent channel providing an over flow to determine the solution line in said tank,

the discharge of said infiuent apron being posi-.

tioned substantially at said solution line; a bottom board in' said channel extending between and sealed to said front and back boards; an inverted V-shapecl baffle extending across said tank parallel to said front wall between said,-

apron and said effluent channe1 and inclining downward toward both the front and rear walls of said tank in closely spaced relation to the former; a bottom for said V-shaped baille inclined upwardly from the forward edge to the I? rearward edge thereof; a ridge formed on the forward wall of saidtank below the forward edge of said baffle to deflect ascending gas bubbles against said inclined bottom; an inclined partition in said tank parallel to said front wall and extending from a point above and forwardly of the rearward edge of the bottom of said baffle to receive the gas bubbles therefrom and deflect them toward the rear wall of said tank; a gas cover extending from thei upper edge of said inclined partition rearwardly f to the rear wall of said tank above the solution line therein to form a gas chamber thereover; and means for drawing off the gas from said gas chamber.

9. A combined settling and digesting tank for sewage comprising: a tank of substantially rectangular plan; an inclined influent apron discharging to said tank throughout substantially the entire length of the front wall of the latter}- saidapron being reduced in width to a medial apex as it recedes from said tank; an infiuent channel feeding said tank at the apex of said apron; an effluent channel extending across said tank parallel to said front wall; a front board on said channel facing said apron and extending above said front wall of said tank; a backboard along said efiluent channel providing an overflow to determine the solution line in said tank, the discharge of said influent channel-1- being positioned substantially at said solution line; a bottom board in said channel extending between and sealed to said front and back boards; an inverted V-shaped baffle extending across said tank parallel to said front wall between said apron and said efiluent channel and inclining downward toward the front and rear walls of said tank in closely spaced relation to the former; a bottom for said baffle inclined upwardly from the forward edge to the rearward edge-thereof; a ridge formed on the forward wall of said tank below the forward edge of saidbaflle :tojdeflect ascending gas bubbles against said inclined bottom; an inclined partition in said tank extending from a point above and forwardly of the rearward edge of said bafile to receive the gas bubbles therefrom and deflect them 7 toward the rear wall of said tank; a gascover extending from the upper edge of said inclined partition rearwardly to the rear wall of said tank above the solution line therein to form a gas chamber thereover; and means for drawing gas from said chamber. 7

10. A combined settling and digesting tankfor sewage comprising: a tank of substantially rectangular plan; an inclined infiuent apron discharging to said tank-throughout substantially the length of the'front wall of the latter, said apronbeing reduced in width to a medial apex as it recedes from said tank; an influent channel feeding said tank at the apex of said apron; an effluent channel extending across said tank parallel to said front wall; a front board on said channel facing said apron' and extending above the front wall of said tank; a backboard along said effluent channel providing an overflow to determine the solution line in said tank, the discharge of iniiuent apron being positioned substantially at said solution line; an inverted V-shaped baffle extending across said tank parallel to said front wall between said apron and said efiluent channel and inclining downward toward the front and rear walls of said tank in closely spaced relation to the former; gas bafiling means for preventing rising gas bubbles from passing between the front wall of said tank and said balile; a hopper bottom in said tank; a collection sump at the low point of said bottom; and a lift pipe extendin upwardly in said tank from said sump for removing solids therefrom. v

CARROLL I-I. COBERLY.

REFERENCES CZTED UNITED STATES PATENTS I Number Name Date 2,000,966 Lucke May 14, 1935 1,445,439 1 Imhoff et a1. Feb. 13, 1923 1,757,263 Sims May 6, 1930 1,820,978 Imhofi Sept. 1, 1931 2,021,679 Bevan Nov, 19,1935 1,957,168 jI-Iyde May 1, 1934 1,399,562 Imhoff Dec, 6, 1921 828,515 Schmidt Aug. 14, 1906 872,866 Vial Dec. 3, 1907 1,741,915 Brasack et a1. Dec. 31, 1929 1,889,601 Heinkel Nov 29, 1932 1,658,040 Cohn Feb. 7, 1928 FOREIGNPATENTS Number Q Country Date 106,223 Swiss Aug. 1,1924

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