Note: Descriptions are shown in the official language in which they were submitted.
1~76~3~5
This invention relates to apparatus for aerating sewage
in sewage lagoons, ponds or basins.
Biological breakdown of sewage is a well-known technique
for de-toxifying effluent, and a number of different techniques
have evolved for entraining gas such as oxygen within sewage
fuild or sludge for fueling its biological breakdown. One of
the techniques which is used for aeration is to bubble a gas
such as oxygen or air into the sewage from submerged pipes,
whereupon some entrainment will occur.
~t has been found that the efficiency of aeration will
increase with the maximization of the gas surface area in the
sewage. The efficiency also increases by Mixing. The former
technique re~uires as large a number of bubbles as is possible,
and the second depends on agitation of the sewage. Both tech-
niques are sometimes effected by bubbling the gas upwardly
through a submerged cylindrical container which has baffles
strategically placed either partly across or spiralling in some
manner therethrough. Examples of such submerged cylindrical
containers, which are commonly referred to as static aerator
mixers are shown in U.S. Patent Nos. 4~138,335; 4,169,873;
3~968~Q86; 3,628,775; 3~672,647; and 4,187,263.
The intent of the structure is to cause upward movement
of the sewage by the pressure of differential density of gas
entrained sewage, and shearing of the gas bubbles upon fric-
tional contact with the baffles. Some agitation of the
surrounding sewage has been found to occur, but in the main an
unsatisfactory efficiency has resulted.
It has been found that the mixing efficiency in the
basin can be increased by extending the sphere of mixing
influence of the static aerator mixer installed in the basin
by use of an adapter skirt as disclosed in the present invention.
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In accordance with a particular embodiment
of the invention there is provided, for use in an acti-
vated sludge basin for mixing sludge with an oxygen-
containing gas, an oxygen-containing gas supply means.
Flue means are located above the gas supply means
for mixing gas-entrained fluid sludge thereabout and
directing such sludge vertically therethrough toward
the top of the basin. A skirt is adapted to be placed
about the flue means for extending the zone of mixing
influence of the flue on the gas-entrained fluid sludge.
The skirt includes a body element received about at
least a portion of the flue means and means connected
to the body element for supporting the body element
in such a position so as to radially extend the diameter
of the flue means and to lower the vertical extent of
the outer surface of the flue means relative to the
bottom of the sludge basin.
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The sphere of mixing influence of a static aerator mixer
installed in the bottom of a sewage basin can be extended by
providing a skirt in surrounding relationship to the submerged,
open-ended, cylindrical container or mixer and supporting the
same on the bubble generator pipe ~eneath the mixer structure
or directly on the floor of the basin. This not only can be
utilized to widen the zone of influence of the static aerator
mixer by providing for additional agitation and mixing radially
outwardly from the cylindrical sur~ace of the static aerator
mixer, but the currents can be forced closer to the floor of the
basin to entrain otherwise static sludge~ Further, add;tional
surface area upon which the gas-entrained sludge can impinge
is provided to collide therewith causing the sludge to be more
finely divided wherein it can be mixed more readily with incom-
ing gas to increase aero~ic action and efficiency.
The adapter skirt for the static aerator mixer of the
present invention may take a variety of forms.
In one form, the skirt can consist of a cylindrical
body adapted to be seated and supported on the bubble generator
pipe. The cylindrical body has a cen~ral opening in a top wall
thereof provided with a rubber hose thereabout to frictionally
bear against the outer cylindrical wall or surface of the static
aerator mixer, which is received therethrough.
A second design includes an open-ended frustoconical-
shaped skirt provided with fingers along its upper edge surface
for engagement with the cylindrical wall of the static aerator
mixer. The skirt encloses the lower portion of the cylindrical
mixer which is also received therethrough. The outer surface
of the lower portion of the skirt includes a ledge. Mounted
for vertical adjustment on the ledge are a plurality of support
legs so that each skirt leg may be adjusted to reach the support
floor of the basin when the skirt is installed, so that it ~its
properly on the bubble generator pipe, but ~et is supported by
additional support legs on the floor of the sludge basin.
Still another skirt design may be of the cylindrical
type described above, but provided with adjustable legs as
disclosed and illustrated in conjunction with the second design.
Finally, the skirt can include an upper, cylindrical
portion and a lower~ frusto-conical portion flaring outwardly
away from the side wall of the cylindrical static aerator mixer
which is completely enclosed therein. The lower frusto-conical
portion is provided with a ledge having at spaced, diametrically
opposed portions thereabout an arcuate flange seated on the
bubble generator pipe~ The flange, in conjunction with an
upright support strut mounts a flexible band used to encircle
the pipe to connect the skirt to the pipe. The upper, cylin-
drical portion of the skirt is also provided with interior,
resilient~ flexible fingers circumferentially spaced about the
inner diameter thereof for engagement-with the outer cylindrical
surface of the static aerator mixer to enable the skirt to be
maintained in a relative upright position with respect to the
static aerator mixer.
Further objects and advantages of the invention will
become apparent from the following description and clai~s, and
the accompanying drawings, w-herein:
Figure 1 is a schematic diagram of a prior art activated
sludge basin;
Figure 2 is a schematic diagram of an activated sludge
basin in which adapter skirts comprising the subject of the
present invention have been installed on each of the static
aerator mixers in the basin;
Figure 3 is a perspective view of one fo~m o~ adapter
skirt of the present invention placed in surrounding relation
to a static aerator mixer;
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Figure 4 is a top plan view of another form of adapter
skirt of the present invention;
Figure 5 is a side view in elevation of the adapter
skirt of Figure 4;
Figure 5 is an enlarged, fragmentary, exploded perspec-
tive view of the lower lefthand corner of the adapter skirt of
Figure 5, illustrating the manner in which the support legs
are secured to the body of the skirt;
Figure 7 is an enlarged side view in elevation, with
certain portions in section, of the central lower portion of the
adapter skirt of Figure 5, illustrating the manner of securing
the skirt to a bubble generator pipe;
Figure 8 is a cross-sectional view taken substantially
along the plane indicated by line 8-8 of Figure 7;
Figure 9 is an enlarged fragmentary perspective view
of a portion of the upper edge of the skirt of Figure 5,
illustrating means for gripping the outer cylindrical wall of
a static aerator mixer;
Figure 10 is a top plan view of still another e~bodiment
of adapter skirt;
Figure 11 is a cross-sectional view taken substantially
along the planes indicated by line 11-11 of Figure 10;
Figure 12 is a top plan view of the embodi~ent of
adapter skirt illustrated in Figure 3;
Figure 13 is a cross-sectional view taken substantially
along the planes indicated by line 13-13 of Figure 12;
Figure 14 is a top plan view of yet anothe~ embodiment
of adapter skirt;
Figure 15 is a cross-sectional view taken substantially
along the plane indicated by line 15-15 of Figure 14;
Figure 16 is a cross-sectional view taken substantially
along the plane indicated by line 16-16 of Figure 15; and
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Figure 17 is a cross-sectional view takne substantially
along the plane indicated by line 17-17 of Figure 14.
Referring now in detail to the drawings, wherein like
numerals indicate like elements throughout the several views,
Figure 1 schematically illustrates a prior art activated sludge
basin 10 wherein sludge is mixed aerobically wlth oxygen in
order to promote biological degradation of the sludge. The
basin 10 includes a concrete floor 12 onto which a liquid
effluent 14 containing sludge is deposited. The effluent 14
may-typically consist of waste material from a paper mill.
Supported on concrete floor 12 at spaced locations are
a plurality of concrete slabs 16 supporting an open-ended
cylindrical, static aerator mixer 18 by spaced struts or legs
20 extending between the concrete slab and static mixer aerator
18. A cylindrical pipe 22 is disposed horizontally beneath
each of the open-ended cylindri~cal mixers 18 and includes an
opening beneath the mixer 18 through which a gas such as oxygen
is bubbled. The bubbled oxygen entrains some of the light
sludge 24 filtering from the effluent disposed upon a denser
layer of heavy sludge 26 1ining the concrete botto~ floor 12 and
moves the entrained sludge upwardly through the interior of the
mixer 18 to promote mixing of the gas- with the sludge~
The gas-entrained sludge, being lighter than the sludge
alone~ will rise through the interior of the mixer 18, which
can be equipped with baffles as indicated in any of the afore-
mentioned patents cited above, to further break up the entrained
sludge into finer particles and promote the aerobic mixing.
The entrained sludge will rise through the top open end of the
static aerator mixer and will ultimately fall as indicated by
the mixing current arrows 28 and be recirculated through the
interior of the mixers 18 as indicated by the arrows 30. The
mixers 18 are usually provided with openings 32 in the side
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walls thereof to accomodate the returning gas-entrained sludge.
It has been found that mixing efficiency and aerobic
activity can be increased by extendins the sphere of influence
of the static aerator mixers 18. This is accomplished by
surrounding at least a portion of each of the cylindrical static
aerator mixers 18 with a skirt 33 (see Figure 2) which extends
downwardly beyond the bottom of the mixer and radially outwardly
beyond the cylindrical side wall thereof to cause the mixing
currents to occupy a greater lateral zone through whi.ch they
move as well as causing them to approach the floor 12 of the
basin 10 as illustrated more clearly in Figure 2. Indeed~ the
mixing currents from adjacent mixer structures 18 may overlap
as indicated at 35 to cause turbulent mixing. This increased
mixing influence improves aerobic efficiency, as more sludge
is dissolved in the effluent and subjected to aerobic de
toxification.
One specific form of aerator skirt is generally desig-
nated by numeral 40 and i~ is illustrated in Figures 3, 10 and
11. The skirt 40 includes a cylindrical body 42 proyided with
an annular top member 44 having an opening 46 disposed centrally
therethrough, A split rubber hose collar 48 is secured to the
inner lip of top 44 between the top 44 and opening 46. Collar
48 extends about the entire periphery of the inner lip of the
top 44. Opening 46 is adapted to receive therethrough one of
the static aerator mixers 18 (Figure 3) in frictional engagement
with rubber hose collar 48, which tends to locate the cylin-
drical body 42 and maintain it in an upright position relative
to the static aerator mixer 18. Body 42 widens the zone of
influence of mixer 18 and moves the zone closer to floor 12 of
the basin 10,
The bottom edge or rim 50 of the cylindrical body 42 of
aerator skirt 40 is provided with a pair of semi-circular
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notches 52 which serve to seat the cylindrical body 42 on a
bubble generator pipe 22 associated with the static aerator
mixer 18 received through opening 46. The seating of the
notches on pipe 22 causes the pipe to support the cylindrical
body 42 in a position surrounding the lower portion of static
aerator mixer 18 adjacent to the bottom of sludge basin 10, as
illustrated in Figure 2r
A plurality of legs 54 formed from angle irons are
secured to spaced locatiGns about the periphery of cylindrical
body 42 of the skirt 40 to further support the same on the
concrete bottom floor 12 of basin 10. Lifting lugs 56 are
provided at diametrically opposed portions of cylindrical body
42 of skirt 40 in order to lift the skirt when it is necessary
to remove the same for maintenance and to lower it into surround-
ing relation to the static aerator mixer 18.
A second embodiment of the adapter skirt is designated
in general by the numeral 60 in Figures 4 to 9, inclusive. The
skirt 60 includes a frusto-conical body 62 having a wider bottom
than top and open at its opposed ends. The skirt 60 is also
placed about the bottom portion of a static aerator mixer 18 and
includes a plurality of serrations 64 extending about the
periphery of its upper edge. The serrated edge is placed in
engagement with the outer cylindrical surface of a static
aerator mixer 18 ~not shown) and frictionally maintains the
skirt in an upright relation relative to the outer surface of
the mixer.
An annular ledge 66 circumscribed the lo~er portion of
the frusto-conical body 62 of skirt 60. A semi-circular flange
70 extends downwardly from opposed diametrical portions of
annular ledge 66 in facing relation to an opening 68 extending
from the bottom edge of frusto-conical body 62 towards flange
70. The frusto-conical body 62 of skirt 60 is positioned on a
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bubble generator pipe ~2 by disposing the pipe through slots 68
into seated engagement with opposed flanges 70. A coil spring
72 connected to eye bolts 74 threadedly connected to spaced
portions of annular ledge 66 adjacent to each opening 68 is
wrapped about the bottom arcuate portion of bubble generator
pipe 22 to firmly secure frusto-conical portion 62 of the skirt
60 in spaced relation to the lower portion of the static aerator
mixer 18. The flared nature of the frusto-conical portion 62
extends the zone of mixing influence of the static aerator mixer
18 both radially and vertically towards the bottom of the sludge
basin 10.
Support legs 76 are connected to annular ledge 66 to
provide additional support for the skirt 60 on the floor 12 of
the sludge basin 10 The legs 76 provided at spaced locations
about the periphery of ledge 66 are illustrated in detail in
Figure 6, and are adjustable.
Each of the legs 76 includes a substantially rectangular
bar provided with an elongated slot 78 therethrough. Bar 76
is received within a groove 80 and is relatively, ~ertic~lly
adjustable therein. Groove 80 is formed in the outer face of
a housing member 82 extending vertically along spaced peripheral
portions of ledge 66. Housing 82 has a hollow interior extend-
ing along the angular lower inner surface of frusto-conical
body 62 of skirt 60. Accordingly, a wedge member 84, comple-
mental in shape to the interior portion of housing 82 is
provided so that when wedge 84 is inserted therein a Yertical
bearing surface 86 parallel to bar 76 is provided ~ bolt 88
having a head 90 at one end is inserted through aligned openings
92 and 94 on the wedge member 84 and housing 82, respectively,
and inserted within elongated slot 78 on b~r leg member 76.
A washer 95 and a nut 96 threaded on the opposite end of bolt
88 is utillzed to lock the bar leg 76 in adjusted relative
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3~5
vertical ~elation to the frusto-conical body portion 62 of
skirt 60 so as to res~ on the floor of the basin 10 for support
purposes Otherwise~ when installed, the legs 76 would have
to be shortened or possibly lengthened depending on the partic-
ular installation. ~y virtue of th.e adjustability of the legs
76, the skirt 60 can have substantially universal application.
~ igures 12 and 13 illustrate yet another adapter skirt
100, The skirt 100 is similar to the aerator skirt 40 in that
it includes a cylindrical body element 102. The body element
102 includes a top plate 104 having a centrally located opening
106 therethrough for receiving one o~ the static aerator mixers
18.
Additionally, the bottom lip of the cylindrical body
structure 102 includes an annular ledge 108 having a plurality
of housings 110 mounted about its periphery, each of which
includes a groove 112 or slidably receiving in adjus.table
relation a bar leg 114. A bolt 116 is received through.housing
110 and received in an elongated slot 118 in bar le~ 114 so
that the leg can be adjusted vertically with respect to cylin-
drical body structure 102. In this embodiment, the skirtadapter 100 can be supported directly upon the concrete ~loor
12 of the sludge basin 10 rath.er than on the bubble generator
pipe 22. Further, a plurality o openings 1~0 can be proYided
in annular top plate 104 to receive hooks or ropes for lifting
the skirt so.that it can be removed for maintenance and put
into position about a static aerator mixer 18.
Another embodiment of a skirt adapter is illustrated
in Figures 14 to 17, inclusive, generally by the numeral 130.
The adapter 130 includes an upper cylindrical body portion 132
joined to a flared outwardly, frusto-conical portion 134. An
annular ledge 135 is connected to the lower edge o~ the frusto-
conical body portion 134 of skirt 130. Diametrically opposed
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portions of ledge 136 include a downwardly bent arcuate seat
138 braced ~y a strut 140 (see Figure 16) extending between the
outer surface of the frusto-conical body portion 134 and annular
ledge 136. A band or strap 142 is received about the upper
surface of seat 138 and extends through strut 140,
The skirt 130 can be placed ahout static aerator mixer
18 with the seats 138 encompassing the outer dimension of the
bubble generator pipe 22 as illustrated in Figures 15 and 16.
Straps 142 are then used to connect the skirt 130 to the pipe
22 to support the same about the static aerator mixer 18.
Approximately two-thirds of the way from the top of the
cylindrical portion 132 of the body structure of the skirt 130
is an interior set of resilient fingers 144 formed by an annular
upright plate havi.ng a plurality of s-lots 146 between each pair
of fingers 44 (see Figure 17), The fingers are resilient and
are adapted to be deflected and contact the side wall of the
cylindrical static aerator mixer 18 to right the adapter skirt
130 when supported upon pipe 22 and frictionally grab the side
wall of the static aerator mixer 18. The upper opening of the
cylindrical portion 132 of the skirt 130 includes a pair of
cross-members 148 and 150.
By virtue of the flared, lower frusto-conical portion
134, the sphere of mixing influence of the static aerator mixer
18 is extended ~oth radially and vertically, as in the other
embodiments of aerator skirts. The skirt 130 is self-supporting
without the use of additional leg supports reaching the floor
12 of the sludge basin 10.
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