CA1122541A - Electrostatic and electrolytic clarifier - Google Patents

Abstract

ELECTROSTATIC AND ELECTROLYTIC CLARIFIER

ABSTRACT OF THE DISCLOSURE

A fluid, such as air or water, carrying suspended solids is directed between a pair of oppositely charged, corrugated surfaces in order to subject the flow to an undulating action that increases the frequency with which the solid particles impinge against one another, thereby increasing the rate of flocculation of the solids.
In the case of airborne particles, the corrugated surfaces are arranged in an upright condition so that the flocculated particles attracted to one or the other of such surfaces gravitate therefrom into a conveying mechanism that delivers such particles to a collecting receptacle. In the case of liquid-borne particles, the flow is forced to travel upwardly against the force of gravity after passing between the surfaces, thereby encouraging the flocculated particles to settle out into a sump that is associated with the uphill flow passage. In each case, two sets of charged surfaces may be utilized, the first having at least one of its surfaces insulated from the flow for electrostatic action only, while the second has neither surfaces so insu-lated for electrolytic action.

Description

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l ELECTROSTATIC AND ELECTROLYTIC CLARIFIER

~ hile the best flocculation of suspended solids in a liquid or other fluid seems to result when the fluid is subjected first to an electrostatic treater, and secondly to an electrolytic treater, even when taken individually, the action obtained with each of said treaters may in many instances be improved when the electrodes thereof are corru-10 gated rather severely so that the flow, when forcedto travel through the undulating pathway defined by such corrugated surfaces, is undulated to such an extent that the suspended solids impinge against each other with greater frequency, thereby increasing 15 the rate of flocculation. Moreover, I have developed a composite unit that combines both an electric treater and a clarifier in a single unit so that the effluent leaving such unit contains a lower concen-tration of suspended solids than heretofore possible, 20 thereby requiring less settling time in open basins and the like downstream from such treaters.
Accordingly, one important object of the present invention is to continue many of the important principles of my prior inventions, but 25 at the same time to expand upon and in many instances provide alternatives for such principles.
Another important object of the present invention is to provide a way of increasing the frequency of collisions or impingement of solid ., ~

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particles w~th one another during passage t~rough a treating unit, electric or ot~er~lse, such as to therefi~ increase the likelihood of forming floc from the suspended solids o~
sufficient size that it can be readily settled out.

An add;tional important ohject of this invention to em~ody means for achieving the foregoing object in structures that are designed primarily for liquid flow and structures designed primarily for gaseous flow.

Another important object of the invention is to provide a treating unit of composite design that combines both electric treating sections and clarifier or settling sections in a single unit, thereby providing for a lower level of solid particulate matter in the effluent leaving the treater : than has heretofore been possible.

In general terms, the present invention can be defined as an apparatus for use in removing suspended solids from a fluid comprising: means defining a pair of opposed, oppositely electrically charged, corrugated surfaces facing one another; means for directing the fluid along a predetermined 10w path between said surfaces, said surfaces ha~ing the longitudinal axes of their corrugations extending transversely of said flow path to cause undulation of the fluid as it flows across the corrugations and therefore encourage solid particles to impinge against one another and join together in larger masses, the corrugations on each surface presenting alternating peaks and valleys, the inwardly extending peaks of the surfaces being aligned with one another so as to present alternating ;
zones of constriction and expansion along said flow path; and an additional pair of opposed, corrugated surfaces downstream :`
3a from said first-mentioned pair, said additional pair haYing the longitudinal axes of their corrugations arranged trans-versely of the flow path there~etween said surfaces of each ~zz~

pair ~eing oppositel~ chargQd electrically ~ith at least one surface of said ~irst~mentioned pair ~eing electrically insulated from the fluid and neither of the surfaces of said additional pair ~eing electricall~ insulated from the fluid.
In the drawings:
Figure 1 is a schematic view of a system employing the principles of t~e present invention;
Fig. 2 is an enlarged, fragmentary, vertical cross-sectional view of two major treating components of the system 1 a in Fig. l;
Fig. 3 is an enlarged, fragmentary, vertical cross-sectional view of a pair of corrugated treating surfaces in the electrostatic treating unit of the system;
Fig. 4 is a view similar to Fig. 3 of corrugated surfaces in the electrolytic treating unit of the system;
Fig. 5 is an enlarged, cross-sectional view of the corrugated surfaces of the electrostatic unit taken along line 5-5 of Fig. 3;
Fig. 6 is an enlarged, vertical cross-sectional 2a view of an alternative arrangement for the 3a ~ ~2a~

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1 corrugated surfaces suitable for either electrostatic or electrolytic use but illustrating by way of example the electrostatic usage; and Fig. 7 is a perspective view of a treater intended primarily for use in removing airborne solids.
The reservoir 10 receives a body of liquid to be treated through an inlet 12 and discharges the liquid through an outlet 14, assisted in this opera-: 10 tion by a pump 16. The pump in turn delivers the liquid into an electrostatic treater 18, from whence it is delivered to an electrolytic treater 20 via a short conduit 22. The effluent ultimately leaving the electrolytic treater 20 through discharge line 24 15 may then be directed into a series of settling basins26, 28 and 30 if so desired.
The two treaters 18 and 20 are of virtually identical construction, the only exception being in the nature of their specific electrode constructions, 20 and therefore the following description will be directed toward the treater 18 only, with the under-standing that the same principles apply to the treater 20 and the latter's components will be desig-nated by ~he same numeral as those of the treater 18 25 with the addition of the letter designation "a."
Treater 18 has a pair of vertically stacked tanks 32 and 34, the lower tank 32 being adapted to encourage flocculation of solids that are suspended in the treated fluid and the upper tank 34 being 30 adapted to promote settling out of such flocculated solids, and, thus, clarification of the liquid. An inlet 36 is coupled in flow communication with the lower tank 32 via entryway 38, while such inlet 36 5~

1 is isolated from the upper tank 34 by means of a trans-verse partition 40. The lower tank 32 is inclined downwardly away from the entryway 38 and inlet 36 so that there is an inherent tendency for the liquid entering the tank 32 to flow from left to right through the latter (viewing Fig. 2) toward a con-necting passage 42 that joins the lower tank 32 with the upper tank 34. Passage 42 is essen~ially verti-cally disposed and is defined partially by a baffle 10 44 disposed across the downstream end of the tank 32 such as to force the liquid leaving the latter to abruptly change directions in order to enter the passage 42. An inclined top wall 46 of the tank 32 serves also as the inclined floor of the upper tank 34.
A sump 48 is located at the downstream end of the tank 32 in association with the passage 42 and the baffle 44 for the purpose of collecting floccu-lated particles that are unable to overcome the force of gravity and travel upwardly with the liquid flow 20 into the upper tank 34. If desired, although entirely optional, a second sump 50 may be provided at the upstream end of the tank 32, although it is contem-plated that such sump 50 will noi normally be required or of significant value in conjunction with the 25 first treater 18, its usage becoming more beneficial in com~ection with the second treater 20 wherein particles will already have been subjected once to an electric action by the time the sump is encountered.
A nozzle 52 or the like situated immediately adjacent 30 the downstream end of the tank 32 at the upper end of the sump 48 may be used to inject air or other gaseous bubbles into the flow for the purpose of agi~ating the liquid within the tank 32. Moreover, as will become apparent below, as a result of the electric 35 field established within the tank 32, the bubbles .~

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I from nozzle 52 will become charged, providing an : attractive "particle" against which the solid particles may become attached, thereby augmenting the floccu-lating action. An additional nozzle 54 below the upstream end o~ the tank 32 and at the head of the : sump 50 may also be employed.
- The upper tank 34 is in the nature of a clari~
fying or settling basin, and as such has a weir 56 - rising above the floor 46 adjacent the outlet conduit 22 for the purpose of maintaining a predetermined liquid level within the tank 34. Once the fluid reaches the top of the weir 56, it can flow over the - latter into the outlet 58 that evolves into the conduit 22.
The treater 18 may be flushed periodically to remove accumulated sludge by virtue of a flush tank 60, holding a supply of flushing liquid, that is cont-rolled by a suitable valve 62 associated with a flush line 64 that communicates with the entryway 38 at the upstream end of the tank 32. Valves 66 and 68 control discharge lines 70 and 72, respectively, from the sumps 48 and 50, such valves 6~ and 68 being - opened by their respective actuators 74 and 76 at such times to provide escape outlets for the accumu-lated sludge and flushing medium.
As illustrated schematically in Fig. 2, but in more detail in Figs. 3 and 5, the tank 32 houses electric field generating structure in the nature of vertically spaced layers of electrodes. ~s illus-trated in Fig. 3, each adjacent pair o electrodes 78 and 80 are connected to opposite sides of a source of direct electrical potential for the pur-pose of generating an electric field therebetween.
At least one of such electrodes 78, 80 is insulated from th~ liquid that flows therebetween, in this llZZ54~ -.
instance both electrodes 78 and 80 being fully insu-: lated. One expeditious way of accomplishing such arrangement has been found by sandwiching a layer of conductive metal foil 82 between two dielectric layers 84 and 86 as illustrated with respect to the - : positively charged electrode 78. As a result of ~ such insulation, there is no current flow across the space between the electrodes 78, 80.
Each of the electrodes 78, 80 is corrugated transversely of the direction of fluid flow there-through so as to present a pair of opposed, cor-rugated surfaces between which the li~uid must flow in order to reach ~he downstream end of the tank 32. In Fig. 3 the ridges 88 of the adjacent electrodes 78, 80 are aligned, as are their valleys 90, such that the flow is of generaLly uniform width, although serpentine, from the upstream end to the downstream end of the tank 32.
In Fig. 5, however, showing an alternative electrode arrangement, it will be seen that the ridges 188 of one electrode are aligned with the valleys 190 of the other electrode, thereby pro-ducing alternating zones of expansion and con-traction to which the flowing liquid is successively subjected during its movement through the tank 32, Note urther in this latter arrangement that the lines oE Eorce between the opposed electrodes 178 and 180 are concentrated at the points where the path is the narrowest, as contrasted to the arrange-ment in Fig 3 where the lines o force are sub~
stantially evenly dispersed throughout, In either arrangement, it is to be noted that the ].ongitudinal axes of the corrugations, defined by the ridges 88, 188 and the valleys 90, 190, as the case~may be, extend transversely of the flow of the fluid, . .

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The tank 32a of the electrolytic treater 20 : differs from the tank 32 of the electrostatic treater 18 only with respect to the nature of its electrodes.
In the tank 32a, the electrodes 78a and 80a have no dielectric layers and are, thus, not electrically : insulated from the flowing liquid. Consequently, ~ electrolytic action occurs.

OPEl~ATION OF .THE ~:MBODIMENTS
IN FIGS . 1- 6 l~hen the liquid containing suspended solids enters the treater 18 through the inlet 36, it is prevented from entering the top tank 34 by the parti-tion 40 and is directed instead through the entry~ay 38 at the head of the tank 32. As it flows from left to right viewing Fig. 2 through the tank 32, it is undulated rather dramatically by the transversely cor-rugated surfaces presented by the electrodes 78, 80~
Thus, in addition to the effect of the electric field on the liquid tending to flocculate the suspended solids, the undulating movement imparted to the liquid causes an increased rate of collision or impingement between the solid particles, thereby augmenting the work of the electric field. Further augmenting this action is the presence of numerous gas bubbles from the nozzles 52 and 54 which become charged by the presence of the electric ~ield in the tank 32 to not only agitate the liquid ~urther, but to also provide adhering surfaces for the particles.
Consequently, by the time the liquid reaches the downstream end of the tank 32, a sufficiently large amount of flocculation has occured so that some of the floc can be settled out. This is en- :
couraged by the presence of the baffle 44 and the upright nature of the connecting passage 42 to the ..

i 1 upper tank 34, this arrangement forcing the liquid to abruptly change directions and move upwardly against the force of gravity such that flocculated particles will tend to settle down into the sump 48.
Thos particles which have not flocculated sufficiently to drop out of the liquid during its upward movement through passage 42 are carried upwardly into the tank 34 where additional settling can occur. As a result of the weir 56, the level within the 10 tank 34 must reach a preselected height before fluid can depart through the outlet 58. Consequently, the liquid pools behind the weir 56 to promite settling out of the solids, which in turn have a tendency to slide down the inclined floor 46 and drop through 15 the passage 42 into the sump 48.
Normally, the desired amount of separation of the suspended solids from the liquid carrier cannot be obtained with the treater 18 alone, and thus the effluent from the treater 18 is directed 20 through the conduit 22 into the electrolytic treater 20 for a second treatment. The undulating action imposed upon the liquid by virtue o. the corrugations within the tank 32a is the same as that obtained within the electrostatic tank 32, but in tank 32a 25 the liquid is exposed to a more powerful electric action in the nat~lre of electrolysis. The floc-culated particles leaving the tank 32a must once again overcome gravity to travel through the passage 42a into the clarifying upper tank 34a such that, 30 at this point, the floc tends to settle into the sump 48a. Upon reaching the tank 34a, further settling and clarification occurs as a result of the weir 56a causing the liquid to pool sufficiently to induce the flocculated particles to settle onto 35 the floor 46a and subsequently slide down the latter into the sump 48a.

' llZZ541 From the electrolytic treater 20, the clarified liquid may travel through the discharge line 24 into the final clarifying tanks 26, 28 and 30, if desired, although it has been found in many instances that such additional clarification : by the tanks 26-30 is not required. Sludge that - accumulates within the sumps 48 and 48a, as well as any that may have accumulated in the s~mps 50 and 50a, may be periodically flushed by opening the valves 62, 62a; 66, 66a; and 68, 68a. Normally, - it is contemplated that the valves 68, 68a will remain closed until after the tanks 32, 32a have been flushed with the valves 66, 66a open, thereby assuring that the flushing medium does, in fact, flow properly through the tanks 32, 32a.
When the electrodes 78, 80 and 78a, 80a are arranged in the manner illustrated in F'igs. 3 and 4, the flowing liquid is not exposed to as aggressive an action as that obtained with the electrode arrangements illustrated in Fig. 6. In the latter arrangement, the alternating squeezing and releasing action has in some instances been found to be too violent; and in such instances, the gentler arrangement of Figs. 3 and 4 is to be preferred. Each case must be decided on its own merits, considering the nature of the influent and the resistance to flocculation o-f the solids sus-pended therein.

DUST COLLECTOR OF FIG, 7 The collector 92 operates in many respects like the treating arrangement of Figs. 1-6 because gaseous-borne solids entering the inlet 94 are sub-jected to transversely corrugated surfaces presented l~ZZS4~
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by the pack of alternately charged electrodes, two of which are indicated by the numerals 96 and 98, respectively. Preferably, the electrodes 96 and 98 are of the insulated "sandwich" construction illus-trated in Fig. 3 so that no electrical current flows therebetween. The undulating action imparted to the gas flow causes an increased frequency of collision of the solid particles, and the charged nature of the electrodes 96, 98 provides attractive surfaces for the particles which may themselves be oppositely charged.
The electrodes 96, 98 are vertically disposed within the housing 100 such that particles collecting thereon will inherently gravitate into the conveyor mechanism 102 (illustrated in the nature of an auger 104~, whereupon they can be drawn off into the collecting receptacle 106. The gas itself may be exhausted from the collector 92 through the stack 108 situated at the end of the housing 100 remote from the inlet 94.
In the case of the liquid treating system illustrated in Figs. 1-6, such an arrangement has been found to be particularly, although not exclusively, useful in connection with a dairy processing facility wherein it is necessary to remove such suspended solids as whole milk, cream,butterfat, yogurt and even some fecal materials. The collector of Fig. 7 has been found to be extremely helpful in connection with dryers that.are used to remove the moisture from sludge obtained by using ~he system of Figs 1-~, the dryers by virtue of a strong airflow tending to entrain minute solid particles from the sludge and discharge the same into the atmosphere unabated when the collector 92 is not used.

Claims (2)

I claim:

1. Apparatus for use in removing suspended solids from a fluid comprising:
means defining a pair of opposed, oppositely electrically charged, corrugated surfaces facing one another;
means for directing the fluid along a predetermined flow path between said surfaces, said surfaces having the longitudinal axes of their corrugations extending transversely of said flow path to cause undulation of the fluid as it flows across the corrugations and pinge against one another and join together in larger masses, the corrugations on each surface presenting alter-nating peaks and valleys, the inwardly extending peaks of the surfaces being aligned with one another so as to present alternating zones of constriction and expansion along said flow path; and an additional pair of opposed, corrugated surfaces downstream from said first-mentioned pair, said additional pair having the longitudinal axes of their corrugations arranged trans-versely of the flow path therebetween said surfaces of each pair being oppositely charged electrically with at least one sur-face of said first-mentioned pair being electrically insulated from the fluid and neither of the surfaces of said additional pair being electrically insulated from the fluid.

2. Apparatus as claimed in Claim 1, wherein said surfaces are disposed to incline said flow path downwardly in the direction of flow.