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Патент USA US2404701

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' July 23, 1946.~
Original Filed July 6, 1942
Patented July 23, 1946
2,404,701‘ a
John J. Felsecker, Calumet’ City, Ill.,.ass'igrior to " ‘
Graver Tankl& Mfg. 00., Inc., a corporation of‘ '
> Delaware
Original application July 6, 1942, Serialv No.
449,968, now Patent No. 2,377,545, dated ‘June
5, 1945. Divided and this application January‘
10, 1944, Serial No.'517,741
‘ 5Claims.
(01.210916 ‘
‘ This invention relates to liquid treatment and
Figure 2 is a similar view of a modi?ed em‘
particularly to the removal of suspended, col
loidal, or dissolved solids from liquids by chemi
cal and physical treatment, with clari?cation by
sludge ?ltration and sedimentation; The soften
ing of water by an improved lime-soda process
is typical for many applications of the invention,
and special reference will be had to this appli
cation, which illustrates the invention but is not
intended to limit the same.
Figure 3 is a diagram
of liquid‘?owsin‘the
paratus of Figure l.
v '
_1 ‘
The tank ID has an inlet ll, through‘which it
receives the newly introduced hard‘ water,‘previ
ouslyldosed with any required-softeningrandsco
agulating chemicals, or other 'pr'ecipitants.“ ‘The
tank is'shown round,'and substantiallysubdivided
10 into three ‘ concentric compartments; by‘ two an
It is an object of this invention to provide an
improved method and apparatus capable of puri
fying a liquid of solids contained and formed
nular, concentric ‘partitions, the inner‘, one; of
which is‘shown at l2 and‘ forms a central ‘stand
pipe, while the outer‘is shown at ‘l3 andiis' rela
tively close‘ to the tank‘wall l4. ‘These-partitions
Another object is to provide ?ltration of the 15 I2 and: l3‘extend vertically from the t'opaof the
liquid being treated through‘ some of said solids,
tank to points above the tank bottom I 5. An air
which are kept in suspension, forming a sludge
blanket, this sludge blanket being initially built
lift or central mixing chamber 16 is surrounded
by ‘the central standpipe '12, and an"annula'r
up from the bottom of the tank, and being so
chamber 11 for primary precipitation treatment
disposed in normal operation as to merge with a 20 is ‘confined by the tank wall l4 and the‘inner
sub-jacent zone of solids settled from the liquids.
‘wall l3; Radial pipes‘ 18 are installed adjacent
the top of the tank, between the top 1'of the cen
and solids to flow as a distributing flow through
tral standpipe l2 and the top of the wa1l'fl3,
a liquid body, spaced above the bottom and be
whereby the toplof the airlift ‘chamber l6 com’
low the top of the liquid body, tocontrol or ad 25 municates with the top ‘of the'pri'mar'y precipi
just the agitative e?ect of the solids distributing
tation chamber I'll and “discharges, tangentially
flow on solids present above and below the same,
thereof, to provide or 'promote a spiral‘ ?ow, in‘
so as to suspend’ small and medium particles
cluding a rotation of the “liquidwin said'chamber.
above the same and to settle large particles be
The inlet pipe I l enters the ‘top of the primary
low the same, and to clarify the liquid by sludge 30 chamber I1. 011 the inside? of ‘the ihner‘annular
?ltration in a ?ow upwardly branching off from
wall l3, and adjacent to its top‘, there is an an
the ‘distributing flow, and by sedimentation‘of
nular over?ow weir l9 providing for the‘ discharge
solids below the distributing flow.
of softened and clari?ed water into a "circular
According to a particular feature I recirculate
launder 20 discharging through‘ane?luent‘con
parts of said distributing ?ow into the mixture to
duit 2|. ‘The weir determines‘the low'est‘point to
be introduced, whereby changes in the flow rate
which the liquid level inthe ‘tank can‘ fallin op‘
of the mixture may be compensated for, the dis
eration, except when the tank‘lis ‘drained for
tribution of liquid and solids in the solids blanket
cleanout or‘re‘pair.
' ‘4
‘ “
may be improved, precipitation and ?occulation
The water received ‘through the‘ inlet :IlI‘m'ay
' ' Another object is to cause a mixture of liquid
promoted by sludge recirculation, and other ad- 440 carry flocculent material, “andi?o'c‘s will be 'pre
vantages obtained.
cipitated‘ as the'jwater ?ows through the ‘tank.
Other objects are to provide favorable condi
The process carried out in this tank is vof'the
tions for the sludge blanket and Other operative ‘
zones and parts of the liquid, as well as suitable
ried along or suspended by the‘liquid?ow,‘ while
means for controlling, guiding, stilling, or segre- ”
large solids or flocs settle to' the‘ tank‘ bottom
gating the‘?uid flows, suitable passages and open
ings for the circulating ?ows, means for adjust
ing the distance or relationship between the solids
distributing ?ow and adjacent ?uid bodies, and
mary ‘wel1 l3, and flocs may settle on the bottom
below that well; ‘ This bottom is substantially‘ flat,
other necessary or desirable equipment.
Still other objects and advantages may appear
on consideration of this disclosure.
In the drawing,
I5. This settling of flocs may start in‘the ‘pri
especially in large tanks. Portions of the‘ settled
solids are continuously picked up "and laterally
removed by scrapers 22, which slowly rotate 1over
the bottom,‘being driven by a motor 23 and speed
reducer 24,' through a central vertical shaft 25.
Figure 1 is a cross-sectional elevation of ap
paratus embodying this invention.
type wherein ‘smalland medium size ‘?ocs are‘car
' 65
The solids removed by the scrapers“ ~are‘received
in a central sump ZB‘from which they are ulti
mately Withdrawn,
chemical composition may be exceedingly small
through a conduit 21.
or light when originally formed. At every point
The'water carrying all the ?ocs except the
largest, which have settled out in the primary
process of formation, treatment, or removal,
well l2_ ,’?OWS ‘horizontally jinwa-rd into' and
throughthe distribution zone 28, passing ,?rst
"are relatively large, heavy,j prematurely formed, '
of a liquid ?ow containing such precipitates in ‘ 7
:therewillbe found some such precipitates which
and. readily settleable, and others of intermediate
‘below the lower edge 29 of the annular wall I3
and ?nally upward, through the sludge ?ltration, f . : size, weight, and settling characteristics, There
zone 30., The distribution zone 28 is locate-din . _may he still others which are so light, smaller
incomplete as to settle relatively slowly or not
the space inside of the wall I3 at an elevation
adjacent to that of the lower zedgeli?iofisaid Wall, ,ito settle ;at :all. _. :In connection with the latter
'igliounetheljermay be mentioned those hardness
while the sludge ?ltrationczone :39 extends 11p
constituents ‘which are still present in. a dissolved
wardly from this distribution zone, inside of the
or similar state, .which have not completed their
wall l3. The rotation of the liquidacontinuesin
the distribution zone 28. ltisanaidto-floccula-7,; ichemicalreaction ,With the softening, precipitat
tion. It also serves to freely,"clistriloute?lliduid ; ilirlghorscoagulating reagents, or which have not
completed the :physical reaction of precipitation
and solids over the tank area. Therefore this
or ?occulation incident to which they appear for
rotation may be allowed to continue at least in
the v?rst time as suspended, solid particles or
a part of the upward ?ow through the sludge
?ltration zone 30. However, ultimately this ro 20 flocs.
.:In accordance herewith the water and the :rel
tation :maylbe .stilled' by vertical radial :ba?les 3!
"and/‘Ely incomplete precipitates. are continuously
which extend inward from the wall l3. ‘There
contacted v-:vvith :a retainedsludge of previously
‘upon, :the :further :upward ‘flow is substantially
-;fcrmed precipitates of intermediate size and
.-:However.,:only .part ‘of the {water entering the 25 ‘weight; ‘the largest, heaviest, completed precipi
straightlined and vertical.
tates being removed'by sedimentation, ‘as soon ‘as
they ‘have -:been < formed. Inithis process, :3, ‘1iquid
distribution zonev 2‘8 hows "upward through the
sludge:?ltration’v zone '39 and, over the ,weir- l9.
particle :may pass throughthe 'tank ,iingan , aver
t?notheripartlrof :thisrwateriisidrawn/ into aibottcm
openingsor ropenings a 32 of the: standpipe :12, :upon
l-operation‘i'of an‘ airlift .‘=device 13:3.v “This :airliit
rage period "of :one ‘hour ;:or 'less.‘
~30 part of this period, ?ocs'may :becriginallyiformed,
by primary precipitation {in ‘the liquid particle.
During the greatest partw-fthis :time thegliquiid
device comprises‘ :a source of compressed‘ air ‘(not
shown), iajlpipe 2341mm that .source. .to-ia slower,
l-lin‘ner ip‘art of :‘the :space de?ned my {the inner
; periphery ZQfJi?hG standpipe <12, and :airdistributor
:means? ‘a’b'thelend ofithis pipe within said space.
*AS) air escapes ,‘from :this‘ distributor :;a mixture
"particle, ‘carrying a continuously ‘decreasing
amount of solids, perc'olates through the :‘sludge
-,blanket:; thatgis, through a retained :mass. of
iof :air, ".water,'sludge .and chemicals :is formed
*twithina the standpipe, :andt'his mixture tendsx'to
vw‘agglomerated, and increased :in "size. :A small
solid particle-originally formed in the primary
‘?ow ‘may'beipresent :inrthis mass :for manyhours,
solids previouslyformed-vangdFbeing-newlyformeld,
;rise,;due to ithe Iact'athat it :has a ,llowergspeci?c
“or :even days, during vwhich vtime-it generally —in
creases in size-dueto agglomeration with :cthe-r
particles previously ~formed or being snewly
formed. The larger a particle becomes, the, more
‘it ‘tends to subside in‘the ~mass>or blanket of par
weightgfthan'ithe surrounding ‘fluids. :Sin'cewth'e’
‘top .011’ :thestandpipe ‘fl 2 , communicates with other
> zonesrthrough the passage ways 1.8., l1, and ,28,
wlhichureturnito the openings 32, a:c1los'e.drcirc_ula—
tion of ‘said mixture'is established :fand :main
tained, alongL-said :passage ‘sways, _; and :in the .di
' _tioles. ' ‘Occasionally,
particles will be partly
broken up, when ‘engaged by (rapid port-ions of
the spirally rotating ?ow; whereupon they may
traction :asiindicated. This circulation ‘can :oon
time in case oiaa :‘SIOW?dOWD or, shut-down of :the
.tendrto'riseagain, The spirally rotating flowi-of
throughput-?ow EWhiChiDI‘iSBS through the sludge
"?ltration [zone 30am :the :overflow _;weir 1| 9.
this invention, as stated before, ‘is upwardly
spaced and functionally separated from the
V lAsludge-?j-ltenu blanket” isibuilt u-pii-n the
zone (30,: ‘The treatment :of the -Water_is com
quiescent ‘sedimentation zone, .and thus disturb~
;pletedrin thissludge?l-ter. Treated ~wate-r;emerges
‘58,1105 ‘ of the sedimentation zone is prevented.
lifmm ’:-the sludgeq?ltercand over?ows over; the
“weir 41:9,.‘ iThe’solids or y?ocs ~,agglomerat_e, ‘and
large, heavy, ‘and ‘well coagulated ?ocs, ‘which'are
architimately removed r-bygsettling down through
55 no longer readilysubject ‘eitherto 'distintegration
the “sludge ?ltration and distribution zones “34)
~.a-nd';28iinto a quiescent;sed-iment~_zone 371Which
extends downwardly from thedistribution zone
“or togrowth under theeconditions of the process.
The particles are ultimately agglomerated into
These aresno longerretainedin the sludge blank
et,--:but removed by sedimentation. As theyset
'tle through :the sludge’blanketvand into the (sub
Relatively puiescent conditions are-maintained 60 ljacent-sediment zone they :displace liquid-up
wardly. These downward‘ and upwardyexchanges
in this sediment 'zone '31, whilethere is relative
commotion ‘due Ito the spiralling, distributing
,or movements sarepreferablyallowed to (occur
flow in the ‘superposed distribution zone 12,8.
throughout (the whole area of thesludge (blanket,
.or atleast insubstantial parts thereo?rso ‘as to
, ;For<azcomplet_e ‘understand-ingot the operation H
*‘OfiiIlIlY improved process and _-apparatus, it must
.be ,-considered ‘that, :when ‘softening reagents are
.‘added' to gazhard :water, the :resulting solid pre
facilitate ‘and accelerate the gravitational {sepa
ration of,~the large, heavy, and completes-docs
cipitates -~or 211.095 of hardness constituents ‘are
from the sludge retained in ‘the?lter'or blanket.
In order to -:start the operation I ?llthextank
'formed at vdifferentmates,‘(velocities, and degrees
ofacompleteness. Some calcium ‘carbonate “?ops
Thereafter, I continuously add water and chemi
of {fair :size may appear vafter :a few minutes,
whereas zotherrsol-id particles Offthe-same sub
,stance'lmayrappear;only;:after“many hours. :Also,
:some of :said :?ocs, :as loriginally formed 1may ib'e
“large or heavy, whereas other solids of the same
1-0 with-water I to the .level, of (the overflow iweir ‘I 9.
cals through the inlet 3H and withdraw equal
amounts of water through'the eli‘luent piped I. In
the beginning, the chemical treatment results in
conditions ‘which , are none better than those .ob-,
tained in earliersoitening apparatus; andtfor this
reason, the initial rate of ?ow orv throughput
according to the'present invention contains only,
through the tank is preferably kept ‘ very slow,
or “at least primarily, the sludge which ‘fails to set
tle into the sediment zone 31; that is, the does) of
that'is, ordinarily less than one gallon per square
footof ‘tank area per minute. With‘higher ini-" '
tial flow rates,>most of :the'flocs formed are en
trained and carried out with'the water over-flow
ing over the weir l9, and a‘isludge bed is formed
only after a longer period of‘ initial treatment.
The desirable; slow, initial rate of flow-maybe
enforced by ‘proper' adjustment of ‘a float-inlet
.valve 38, which may have a disc 39“actuated‘ by‘a
?oat 40 through ‘a linkage 4| comprising a‘ crank
'42 which is angularly ‘ adjustable on the ‘valve
stem 43; or adjustment may'b'e obtained?in- other
‘suitable ways. Even‘ with such a slow 'rate‘of ini.‘
tial‘ ?ow, many of the ?ocs initially'formed are
andlremain so ‘small that ‘they are carried‘ out
overthe'weir I9‘. For ‘this “reason ithe‘water dis
charged ‘during ‘ initial operation is 'generally'un
small and medium size, which are readily subject
to growth and agglomeration under the condi
tions of the process. The ?ow conditions affect
ingyand surrounding‘this improvedrslud'age bed 35
in. 1Tn‘orrrial operation; are diagrammaticallyshown
in'l-Figure'3. The ?owA which passes into and
v16 through ‘the primary» precipitation zone I‘! enters
the distribution zone 28, wherein it is continued
by‘ a horizontal, preferably‘ spiral ?ow ‘B, bring
ing liquid and solidsto 'all points below and in‘the
sludge blanket. The sludge blanket¥36 ‘as ‘a whole
is more or less stationary in the super-posed sludge
?lter zone 30, although considerable liquid‘move
merits may be allowed and even‘enforced therein.
At ‘all points of thedistributin‘g' ?ow Bl, upward
flows C are ‘branched oil? therefrom, which enter
satisfactory ‘for such use or consumption‘as may 20 the superposed sludge ?lter 36 for ?nal treatment
be contemplated‘ for the water when fully treated
Theliquid in the spiral flow B passing through
‘Flocs of calcium carbonate and the like will set
the‘ distributing ‘ zone 28 contains precipitated
tle from the‘slow, initial flow, to thetank bottom
?ocs as‘ well as particles'ju‘st being precipitated,
l5. Preferably during initial operation, these. 25 and perhaps dissolved particles the precipitation
?ocsare not removed through the sludge sump
of which'has hardly started.‘ The upward ?ows
26 and the p'ipe'21. The scrapers 22 maybe kept
C carry the said particles into the sludge‘ ?lter 36,
at rest, or I may rotate them from time‘to'ti'me,
whichias mentioned consists of generally similar
at a very slow'ratel'and for s'hort‘periods' only.
particles, of small and mediumsize. The liquid
in accordance with this invention.
Gradually, the whole of the sediment zone 3_'I may .
be filled with settled sludge.
As the operation‘ continues ‘the sludge ‘sediment
tends to be built up above‘ the bottom zone‘31,
peroolates throughithis sludge ?lter. Incident to
this percolating ?ow; both precipitation and ?oc
culati'onfare promoted and completed. ‘
proper re-adjustments of valve38 or of anyiother
‘The ‘largest precipitated and ?occulatedparti
cles ‘contained in the flow B are constantly settled
out; as‘ shown at D.‘ Furthermore, the largest
precipitated and ?occulated- particlesformed in
control means, ‘so that the sludge present in the
the sludge ?lter zone 30 are constantly settled out
into the distribution zone 28. From this moment
on, if not before, the rateof ?ow is increased, by '
distribution zone 28 is‘larg‘ely re-sus'pended'and
as shown at E. Oth‘er‘?ocs and particles‘tending
the newly entering sludge is largely ‘held‘in susa
to turn into ?ocs. are continuously‘resupplied to
pension, and parts thereof are carried into the 4.0 the sludge filter, by the flow A from the primary
superimposed Zone 30, starting the formation of a
precipitation zone l'l. They are‘uniformly dis
suspended sludge blanket. ‘Of course the‘ chemi-_
tributed by the ?ow B, without undue disturb
cal dosage is increased proportionally.‘ Caution
ance of the quiescent zonev31.
must be applied to avoid any excessive or abrupt
readjustment of valves leading to a sudden or ex
cessive increase in the rate of ?ow, which would
cause the suspended ?ocs to be entrained and
carried out over the weir i9. It must be under
' Practically all‘ the impurities contained in the
liquid entering the sludge ?lter, 36 are effectively
removed from the liquid, in the sludge ?lter, in
cluding even the. smallest particles and the solids
most di?icult to precipitate in settleable form.
Such small particles and incomplete precipitates
stood that at this point, the initial treatment‘is
not fully completed yet. The bulk of the‘initial iii) are agglomerated with and thus retained by the
sludge ?lter consists of small ?ocs. and this initial
medium and‘ small sized, suspended ?ocs forming
?lter cannot be expected to ‘provide complete
the sludge ?lter 36. As a result, there is a con
treatment at a high ?ow rate. The flow rate may
tinuous growth of the suspended ?ocs forming the
be raised gradually, and it must be anticipated
sludge ?lter 36. The smallest and least complete
that for a short time after each increase the over- ‘
?ocs. originally entrained and introduced into
flow will contain relatively more small ?ocs again.
the ?lter, disappearduring this upward flow, and
Gradually, however, the over?ow will become
‘a well softened, clari?ed and stabilized water,
clear, and thereafter it will remain clear, even
upon a further increase of the ?ow rate within
certain limits of tank capacity. This is due to
the fact that the bene?cial e?ects of the sludge
blanket 36 play their part increasingly; and the
docs in the sludge blanket itself become larger
and heavier. A further increase in the rate of
throughput, as mentioned, becomes‘ feasible; in
fact, it is desirable, in order to keep a su?icient
supply of ?ocs in suspension, and to prevent‘ de~‘
pletion of the sludge blanket 36.
‘ ‘
Pursuant to this ?nal increase of_ the through
causing no after-precipitation on continued de
tention‘or ?ow, emerges at F‘, to be withdrawn
at G,
Flocs which have reached a large size, are no
longer suspended,‘ and of course not entrained, by
the upward ?ow C; they settle down to‘ the tank
bottom. No attempt is made to hold them in
suspension. ,They settle through ‘the distribution
zone 28, where they may be engaged‘, partly brok
en up and resuspended by the spiral flow for a
while; but they ultimately settle further into the
sediment zone 31 and are removed by the scrap
‘put rate, the operation may be considered normal,
ers 22, at H.
and may be continued inde?nitely. From‘this
' ‘When‘reference is had to ?ocs of certain sizes,
moment on, sludge must be withdrawn through ‘
the pipe 2‘! at substantially the same rate at which
new sludge is deposited; ‘
l ‘
of course it will be understood that generally
.» speaking, the largest ?ocs are also the heaviest
ones, and settle more rapidly, or overcome an up
The sludge blanket 36 in the ?ltration zone 30 175 ward ‘liquid velocity more easily‘ than other, .
2,;4 0.45710 1
This, of course; willnecessitate the removal of a
relatively- diluted sludge, so long'as the pipe 21 is "
' size andv speci?c-weight‘ may a?ect the settleabil
ityof the flocsalso,_but size is generally themost
important factor, so long as speci?c Weight and
structure are uniform, asis ,‘well knowrrto per
sons'skilled inthis art.
liquid circulatiomcaused by._ thegair lift; is rapid.
smalleraand; lighter ,?ocs. Other ‘features than
' usedafonthist purpose; and such" operation willbe
3,112; exception rather than . the: rule, in most tanks
constructed-in accordancezzherewith.
Reviewing once more the arrangementof the
. Such a‘. change‘, inr..the:.locationfof the openings
several zones, accordingtoFigure 3, I provide four
332::may also iallect the speed ofrrecirculation; since
zones superposed‘ over; one another. These zones
aih‘eavier sludge will berecirculated at a slower
may be identi?edasfollows, starting atzthe tank 10 raterthanl a lightl‘sludge; however,’ this secondary ,
e?ectzgenerally is...insigni?cant, in the‘ water
bottom:-First, the sediment-zone or bottom‘ zone ' treatments‘ contemplated herein; .On the other
31;: ‘second,th'e distribution or spiral‘ ?ow zone 28 ; .
hand, the speed’.orwrecirculatiommay‘be changed
arbitrarily;.- by‘ adjustment? of; throttlevalve 44- in
adjacent to the launder 2.0. The primary zone Il .15 their air? inlet'pipe 34‘. suchra ire-adjustment; of '‘
may, be- viewed as part of they spiral flow zone 28.
velocity of? re‘ecirculation may ‘either promote or
' It‘ will be understood that the saidzones' merge 1 > countere'a'ct the effects ref‘: 2.’ Ireadjustment in the
third, the sludge ?lter or'sludge blanket zone 30;
and; fourth, the zone of. treated and clari?ed water
into one another unobstructedly, except-as stated.
Necessary'steps of the precipitating and coagulat
location.- of the; openings 3-2:; - however,‘ these two
methods; of lreeadjustmentsiare not‘ equivalent to1
ingtreatment occur in- each of the‘ zones, except 20 oneea-nother; . li'orinstance; ,atthe-start of opera
tions; it <i'sjdisti-nctly" more desirableto-lower the
the sediment zone 3‘! and the clear Water zone.’ It
openings 32 than‘itbf enlarge ‘the? openingtthrough
may be said that precipitation, andv coagulation
the; throttle .valve 44, although>= both’. operations
, starts inthe primary zone H, continues in the dis
~ tribution zone'28, and is. completed in the sludge
?lter zone 30. It may also be said that a suspend
ed'sludge ?lter or blanket 36 is presentbelowand
partly aroundpthe zone 39 as Well as within the
would haveorrel effect in commonJ'theyr speed up
the-return oixsludgeto the'distri'bution zone 28.
The-disadvantage in resorting to. a; more: rapid
air feed, ‘at. thatstage, is due to the fact that-un
desirable’ comminution "of ?ocs might resulttthe
flocs- being particularly sensitive'and destructib‘le
same. It has been shown how this sludge ?lter
is initially built. up‘from the bottom of the tank,
where'it merges-intoalayer‘of sediment. 7
30 during‘thisearly'st'age of‘operati'onsb
The location 'of the opening or‘openings 32 is
very important ‘for this process.’v At the start of
Various structures can be usedtmachieve the
vertical,_>adjustment .of .the openings - 32: as 'ex-
no sludge can be re-circulatedby the air lift de
plained: In. ‘the preferred, embodiment‘ of Figure
l,»t-he standpipe- l2 consists ofitwo pipes: 45 and
vice 35 and returned to the distribution zone 28._ r
46 having ‘telescopic engagement with one an
In order to speed up‘ the starting operation,‘ it is
other.»v Pipe 45‘ forms the upper andwouteri part
of ,=the standpipev While a-pipe; tubeor- ringv 46
formsthe lower and.» inner/part. Thislower and
inner part is~closed at the bottom by a plate 41-,
the operation, no sludge bed is present,‘and thus
desirable that the openings‘ 32 be located as close
as'possible to thesludge which accumulates grad
' ually on the bottom of the tank.
Thus the open
ings 32 should be relatively‘ close to the tank bot
tom, at; the start. However, when a vsuspended
sludge bed 36 has been built up and substantially
stabilized to the proper condition for normal op
but has:' a series of openings '32-: around the side
wall thereof,adjacentthebottom plate 41. Ver~ ’
tical rodsjAs aresecured to the top of the lower,
innerpipe~46 and extendiio points adjacent the
top'of; the tank, whereby ‘these rods, and the lower
eration, it is preferable‘ that the openings 32 be
spaced relatively farther above the tank bottom. 46 pipeqor; ring. 46. with openings 32' can be raised
or lowered’ by hand, or by suitable power means
The reason for this is that, as mentioned, light
and medium-weighted sludge particles are most
(not shown).
desirable in the sludge bed 36; such particles
A. modi?cation is shown by Figure 2 which. in
general. provides‘ similar parts. and operation» as
therefore should be recirculated by the airlift; but
the heaviest particles, rather than these more de 50 Figure 1 does, butwherein inlet openings Bl of
the; airlift tube 92 are provided in superposed
sirable ones are found near the‘ tank bottom.‘
rows‘, causing a. particularly good and-deep dis
During a generally normal operation, the con
tribution of- the circulating ?ow below or through
dition of the sludge bed 35 is subject to changes,
the sludge?lter, whereby higher rates of circula~
upon any slow-down or speed-up of throughput
and chemical feed, change of solids concentra 55 tionmay be provided without undue; disturbance
tion, type of solids, pH,-temperature, and other , of‘ the sludge bed. An adjustment similar to that
of Figurejl may vhey-provided by slidable ring mem
conditions of the incoming water, changes in the
bers. or gates 93. Thesering members are c0ncen~
schedule of sludge withdrawals through the pipe
21, and other changes. Asa result, the sludge
tric:with-the air lift tube 92; they may restrict or
bed will tend toehange as to overall depth thereof, 60 close-some. of the superposed openings 9 I, depend
as to percentage of total solids. and of medium
ing on their verticaladj-ustment,andthey mayr be
sized solids,_as to Specific} weight of medium-sized
vertically-- adujstable individually on conjointly;
It.v will‘be‘seen: that by means of. this. modi?cation,
solids, and in . other respects. Such resulting
changes, again, may frequently call for a re-ad
boththe vertical location and the eiiective depth
justment of the location of the openings 32. For 65 of the‘setof; openings vill and.» of the distributing
flowtB enteringv the same. can- be changed. A
instance, if the bed is starved of solids of su?‘lcient
change in.v effective depth or size of. this set of
size and weight, it will be desirable, at least tem
openings is sometimes-desirable,‘ since the‘ size
porarily, to lower. these openings.
initially selected may beF-foun'dexcessive or insuf
Such a change in. the location of the openings
32 will re-adjust the direction of the distributing 70 ?cient requiring undesirablyh-igh or; low veloci
ties of air'feed; these velocities havingvarious ef- '
?ow B, in a. vertical. plane, and thereby in?uence
fects as explained, upon the: speed of recirculation,
the effective dimensions. of the sediment. zone 31
type of sludge entering.‘ the; recirculatiomitype of
and superposed zones. In fact, with a, Very low
sludge discharged into thelsludge bed, distribution
setting of these openings, the sediment zone. can
of materials in the distribution zone‘ andisoqon‘.
be made to disappear entirely atleast when the
chamber, and means associated with one of said
Various modi?cations other than those speci?
cally shown and described will suggest themselves
annular partitions and adapted to raise and lower
at least a lower part of the respective partition.
3. Apparatus for liquid treatment comprising a
tank, two annular partitions concentric with said
to persons skilled in the art, upon a study and
consideration of this disclosure. It will be under
stood that the dimensions, flow velocities, and
similar data speci?ed herein are stated only for
tank, extending from positions adjacent the top
illustration, and are not intended to limit this
This is a divisionn of my application, Serial No.
449,968, ?led July 6, 1942, which has now ma 10
tured into Patent No. 2,37 7,545.
I claim:
of said tank to positions above and adjacent to
the bottom of said tank, and forming an inner
mixing chamber and two outer chambers in said
tank, the top of said mixing chamber communi
cating with the top of one of said outer cham
' hers which thereby serves as a primary precipita
1. Apparatus for liquid treatment comprising a
tank having a peripheral wall, an annular baflle
concentric with said wall and extending from a
point adjacent to the top of said tank to a point
above the bottom of said tank, thereby separating
‘an outer primary chamber from an inner sludge
?ltration zone, inlet means adapted to discharge
liquid to be treated and any reagents required '
into said tank remotely from said sludge filtra~
, tion zone, liquid outlet means adjacent to the
top of said tank in the space inside said annular
:ba?le, circulator means adapted to cause a flow
from the space within the lower part of said an~
‘nular baflie to the space outside of the upper part
of said annular baffle, sludge outlet means asso
ciated with the bottom of said tank, and means
adapted to convey sludge over the bottom of said
tank to said sludge outlet means, said circulator "
means comprising a ?xed updraft tube centrally
and vertically disposed in said tank, means for
liquid communication between the top of said up
draft tube and the space between said peripheral
wall and said annular ba?le, a movable tube in
telescopic relationship with the lower part of said
?xed updraft tube, and means to set the movable
tube in a predetermined position, said tubes being
adapted to provide liquid communication ‘with
the lower part of said sludge ?ltration zone at an
elevation which depends on the setting of said
movable tube.
tion chamber, the other outer chamber being a
chamber for sedimentation and sludge ?ltration,
inlet means adapted to discharge liquid to be
treated and any reagents required into one of
said chambers other than said sedimentation
chamber, liquid outlet means in said sedimenta
tion chamber adjacent the top thereof, sludge
outlet means in said tank vertically spaced be
low said liquid outlet means, circulator means
adapted to maintain a liquid circulation up
wardly through said mixing chamber, down
wardly through said primary precipitation cham
ber and in an inward flow back into said mixing
chamber, the bottom of said mixing chamber
communicating with the other chambers through
at least one opening, and means associated with
the inner annular partition, adapted to raise and
lower said opening.
4. Apparatus according to claim 3 compris
ing means associated with the inner annular par
tition, adapted to enlarge and restrict said open
ing incident to said raising and lowering thereof.
5. Apparatus for liquid treatment comprising a
tank, two annular partitions concentric with said
tank, extending from positions adjacent the top
of said tank to positions above and adjacent to
the bottom of said tank, and forming an inner
mixing chamber and two outer chambers in said
tank, the top of said mixing chamber communi
eating with the top of one of said outer chambers
which thereby serves as a primary precipitation
2. Apparatus for liquid treatment comprising
chamber, the other outer chamber being a cham
a tank, two annular partitions concentric with 45 ber for sedimentation and sludge ?ltration, inlet
said tank, extending from adjacent the top of
means adapted to discharge liquid to be treated
said tank to points above and adjacent to the
and any reagents required into one of said cham
bottom of said tank, and forming an inner mix
bers other than said sedimentation chamber,
ing chamber and two outer chambers in said
liquid outlet means in said sedimentation cham
tank, means for liquid communication whereby 50 ber adjacent the top thereof, sludge outlet means
the top of said mixing chamber communicates
in said tank vertically spaced below said liquid
with the top of one of said outer chambers which
outlet means, circulator means adapted to main
thereby serves as a primary precipitation cham
tain a liquid circulation upwardly through said
ber, the other outer chamber being a chamber for
mixing chamber, downwardly through said pri
sedimentation and sludge ?ltration, inlet means
mary precipitation chamber and in an inward
adapted to discharge liquid to be treated and any
?ow back into said mixing chamber, the bottom
reagents required into one of said chambers other
of said mixing chamber communicating with the
than said sedimentation chamber, liquid outlet
other chambers through at least one opening,
means in said sedimentation chamber adjacent
gate means associated with the inner annular
the top thereof, sludge’ outlet means in said tank 60 partition adjacent said opening, adapted to be
vertically spaced below said liquid outlet means,
raised and lowered with respect to said opening,
circulator means adapted to maintain a liquid
and means extending from said gate means up
circulation through said mixing chamber, down
ward to the top of said tank to raise and lower
wardly through said primary precipitation cham
ber and in an inward ?ow back into said mixing 65
said gate means.
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