Патент USA US2137966код для вставки
NOV. 22, 1938. ' R 5_ RANKlN 2,137,966 SEWAGE SYSTEM Filed March 12, 1935 4 Sheets-Sheet l ATTORNEY. Nov; 22, 1938. 2,137,966 R. S. RANKIN SEWAGE SYSTEM Filed March 12, 1955 ‘4 Sheets-Sheet 2 FIG.9. RENVILLE INVENTOR. S. RANKIN ATTORNEY. Nqv. 22, 1938. I 2,137,966 R. s. RANKIN SEWAGE SYSTEM Filed March 12,, 1935 4 Sheets-Sheet 3 q: .0: 6. i w: .__ INVENTOR. 4___ > RENVILLE S. RANKIN ATTORNEY. Nov. 22, 1938. R. s. RANKIN 2,137,966 SEWAGE SYSTEM Filed March 12, 1935 4 Sheets-Sheet 4 FIG.7 j- INVENTOR. RENVILLE s. RANKIN BY ~ ’ ATTORNEY. Patented Nov. 22, 1938 \ 2,137,966 UNITED vSTATES PATENT OFFICE 2,137,966 SEWAGE SYSTEM Renvllle S. Rankin, Chicago, 111., assignor to The Dorr Company, Inc., New York, N. Y., a cor poration of Delaware Application March 12, 1935, Serial No. 10,660 14 Claims. This invention relates to a clari?cation and treatment system for the removal of suspended solids from liquids. More particularly it relates to improvements in the operation and arrange ment of the system with regard to potential oper ating changes in response to certain varying de mands. \ With regard to its ?eld of application this in vention relates preferably, although not exclu sively, to sewage treatment, or more speci?cally ' to improvements in a clarifying system for sewage (Cl. 210-2) time. ,This speci?c method of'dosing is advo cated because it is economical in the use of co agulating or precipitating agents and is prefer-x able in certain instances to the dosing of the raw sewage at a point ahead of the clari?ers. During 5 the winter months and otherwise however it may be desirable to omit the dosing step, and substi ‘ tute operation of the clari?ers in parallel instead of series. Also certain requirements with regard to the 10 subsequent treatment by digestion of the respec treatment in which periodic operating changes tive clari?er sludges have a bearing upon the are desired in view of certain requirements .of preference of dosing between clari?er stages, in ?exibility, economy,and other plant operating asmuch as this makes a substantial percentage of undosed clari?er sludge available for subse- 15 5 principles, and also in view of such demands as made upon the sewage plant according to sea sonal conditions and ?uctuations. To understand a difficulty in the case of sewage clari?cation, according to one aspect a problem exists in the layout of sewage plants, which has to do with the fact that, as a rule, there is a qucnt digestion. ' _ Objects of the invention are to produce a clari ?cation plant, or clari?cation section of a plant, or sewage treat‘inent plant, which is ?exible in operation, which is economical in dosing and 20 power requirements and in total operating e?i scantiness of hydraulic head between the point ciency, which is optionally operable in parallel of raw sewage supply and the lowest possible and series respectively preferably at a minimum clari?er over?ow elevation, so that a desired gravi total of hydraulic head, and which altogether ; ity ?ow to and from the clari?ers can often only is simple to operate in view of changing operat- 25 be obtained by a very close margin. In a tenta ' ing requirements. To this end the invention con tive example the. upper limitation of the head templates the arrangement of a pair of clari available may be determined by a long approach ?ers at substantially equal over?ow levels and thus adapted for parallel operation, in combina from the respective municipality which the sew ‘9 age plant serves, while the lower limit might be tion with pressure boosting means operative to 30 controlled by the respective water levels of a make up for the head loss when switching the stream or body of water into which the clari?er clari?ers from parallel to series, and preferably v over?ow is to discharge. Consequently, in this respect this invention inoperative when returning to parallel'operation. One feature therefore proposes an arrangement 5 contemplates having a battery of clari?ers v according to which a liquid supply channel has changeable from parallel to series operation. interposed in a portion thereof a rotary mixing Parallel operation can be satis?ed with a smaller device of the type which has suiilcient centrifugal margin of head with both clari?ers arranged on e?ect to act as a low lift pump. _ = or for operating at substantially the same level. This feature can therefore be said to reside in Series operation of the clari?ers requires addi the selective use of a combined mixing device O tional head to compensate for the necessary drop and low lift pump in a ?ow sheet which is alter between the primary and secondary clari?ers. nately operable with clari?ers parallel or in seAnother reason to account for the preference underlying this invention of having the clari?ers Other features relate to a system of interconin the sewage plant arran‘geable for parallel and nections between the respective operating points 45 for series operation respectively, lies in’ a re ' of the clari?cation or treatment plant for selec quirement fo'r chemically dosing the sewage pref tively effecting a desired variety of operating U erably at certain points of the ‘?owsheet. Such changes. dosing may comprise the addition of a chemical Other features revolve around.the details of precipitating agent at certain seasons of the year. structural arrangement and operation of 'a liquid That is to say, when'dosing is required,- as for - conditioning and ?occulating unit to be used instance during the summer months, it is pre in connection with the present. clari?cation sys ries. ferred to interpose such dosing step between a primary and a secondary clari?er, therefore se a ries operation of the clari?ers is desired atsuch tem. 35 _ ' - ' ' ' - 45 50 - Still 'other features relate to the type and spe ci?c arrangement of a low pressure pumping 55 2 2,187,966 means for boosting gravity flow in a liquid clari tioning and ?occulating unit, taken upon Fig. 6. ?cation system, or to the use for this purpose of what is known and may be referred to as a “turbo Fig. 8 is an enlarged detail section of the com bined mixing and low pressure pumping device. mixer” or “turbo ?ash-mixer". A_preferrecl embodiment therefore in a sewage Fig. 9 is an end view upon the ?occulating tank and the clari?er tanks associated therewith. Figures 1 to 5 show ?owsheets disclosing di agrammatically a variety of operating connec .tions which may be selectively established in a preferred clari?cation or .treatment system ac cording to this invention. The system includes as operating elements: A pair of mechanically cleaned clari?ers III and H; a liquid conditioning treatment plant, while simple, compact, and otherwise capable of meeting the various prime requirements set forth above, permits variant modes of operation; with selective use of the clari?ers, ?occulating devices, mixing chamber, mixing device, and various auxiliary channels. That is to say, with parallel connection of the clari?ers the clari?cation plant is‘selectively op erable: with or without dosing in the mixing de vice, or with or without a ?occulating step fol and ?occulating unit collectively indicated by the numeral I2, and‘ comprising a pair of individ ual ?occulating sections or units I3 and H; a lowing the mixing step. . conditioning or mixing chamber or unit l5 as The advantages derived from the foregoing sociated with the in?uent end of the ?occulating ?exible arrangement are not con?ned to the operation of the clari?cation section proper but extend their bene?t further into the subsequent units; a receiving chamber i6 for the mixing able to digesting sludge which has been wholly coagulating precipitable solids in the liquid. At chamber; and a control chamber or arrange ment I ‘I equipped for selective feed distribution 20 step of digesting the clari?er sludge, because to various sections of the system. the arrangement in a broader aspect also in The numeral l3 indicates an auxiliary ar volves the mixing of raw primary sludge with. rangement for dispensing a coagulating or_ pre chemically precipitated secondary sludge, which cipitating agent or chemical; "la a feed line 25 for the purpose of digestion is; considered prefer therefor jointly comprising a device for causing 25 precipitated chemically. . l9 and 20 is shown a battery of sewage digesters. The invention possesses other objects and fea Numeral 2i may indicate a screening chamber tures of advantage, some of which with the fore for removal of roughage. , ' 30 going will be set forth in the following descrip _ The respective operating connections in the di 30 tion. In the following description and in the agrams are shown in the way of arrowed lines, claims, parts will be identi?ed by speci?c names the arrows’ indicating the ?ow direction in the for convenience, but they are intended to be as lines. . generic in their application to similar parts as More speci?cally, Fig. 1 includes an in?uent 35 the art will permit. In the accompanying line 22 leading into the control chamber I1, di-' 35 drawings there has been illustrated the best em rect feed connections 23 and 24 from the control bodiment of the invention known to me, but such chamber I‘! to the clari?ers l0 and II respec; embodiment is to be regarded as typical only 0.‘ tively, over?ow-lines 25 and'26 from the clari many possible embodiments, and the invention ?ers. The‘ numerals 21 and 28 indicate the re 40 is not to be limited thereto. spective clari?er under?ow or sludge lines. 40 In‘ particular there are possible within the In Fig. 2, an in?uent line '29 leads into the scope of this invention ‘a variety of operating control chamber 11, continuing into a feed line ' combinations not enumerated above, such variety 30 to the clari?er [0. An over?ow line 3| from being covered by the appended description, clari?er‘ I 0 leads into the receiving chamber l6 45 claims, and drawings. ' and the ?ow continues through’ the mixing 45 The novel features that I consider character- a chamber l5 into a feed line 32 leading therefrom istic of my invention are set forth with particu larity in the appended claims. The invention itself, however, both as to its organization and 50 its method of operation, together with additional objects and advantages thereof, will best be un derstood from the following’ description of a speci?c embodiment when read in connection with the accompanying drawings in which: Fig. 1 is a diagram showing parallel operation 55 of the clari?ers, with connections active to by pass the ?occulating unit. ' . Fig. 2 is a diagram showing series operation of the clari?ers, with connections active to by-pass 60 the ?occulating unit. . ‘ Fig. 3 is a diagram showing parallel operation of the clari?ers, with connections arranged to in clude the ?occulator unit. Fig. 4 is a diagram showing series operation of 65 the clari?ers, and connections arranged to in clude the ?occulating unit intermediate the clar i?er's. Fig. 5 is a diagram showing the clari?ers in series with one ?occulator section ahead of the ?rst clari?er, and the other ?occulating section intermediate the clari?ers. Fig. 6 is an enlarged plan view of the condi tioning and ?occulating unit including premix ing and distributing chambers. 75 Fig. '7 is a longitudinal section of the condi to the second clari?er II from which leads an over?ow line 33. Respective clari?er under?ow lines 34 and 35‘are indicated to lead from the respective clari?ers l0 and II. Arrows 36 lead 50 ing from the dispensing arrangement l8 indi cate‘ that the line “la in this ?owsheet is active to- introduce a chemical precipitating agent. In Fig. 3 the in?uent 31 splits in the mixing chamber l5, to allow the split portions to con 55 tinue individually through the ?occulating units l3 and I4 as indicated by the respective lines 38 and 39. Corresponding connections 40 and 4| lead from the ?occulating units to the respec tive clari?ers Ill and H. Clari?er over?ows are 60 shown at 42 and 43. Arrows 46 leading from the dispensing arrangement l8 indicate that the line I8a in this ?owsheet is active to introduce a chemical coagulating agent ahead of mixer l6 and ?occulating devices i2, i3. Clari?er.under 65 ?ows are shown at 41 and 48.respectively. Fig. 4 has an in?uent 49 passing through the control chamber 11, to continue into the feed line ~50 toelari?er l0. An over?ow line 5| leads from the clari?er ill to the receiving chamber Hand 70 to the mixing chamber l5 where the ?ow splits to enter into the two ?occulating sections I3 and 14 respectively, the split portions being indicated at 52 and 53. Discharges from both ?occulating sections combine in the line 54 to feed the clari 75 3. 2,187,966 or ?occulating agents into the liquid stream to ?er from which over?ow leaves at 55. Under?ow from clari?er II is shown at 56 to lead away, obtain what is known as a ?ash mixing effect while an under?ow or sludge line 51 from clari?er when the stream thus dosed is drawn through the I0 enters the digesters I8 and 20 respectively in series, digester discharge being indicated at 58. Arrows 50 leading from the dispensing arrange— ment I 8 indicate the introduction of a chemical impeller dévice. coagulating agent. Fig. 5 has in?uent 60 pass through the control chamber I1, by-passing the mixing chamber I5 as by a line 6| to continue into the one ?occu lating unit I3 as indicated by the line 62. A feed connection 63 then leads from the ?occulating unit 13 to the clari?er I0. An over?ow line 60 from the clari?er leads back through the receiv ing chamber I6, to continue via the mixing cham ber I5 into the second ?occulating unit or section II as indicated by the line 65. A feed connection 66 from there leads to the second clari?er II from which over?ow 61 ?ows away. An under ?ow line 63 from clari?er I0 leads to the ?rst digester or digestion treatment stage I 5, while a line 63 carries imder?ow from clari?er II to the point of raw feed for recirculation. ‘Hie enlarged detail of the conditioning and ?occulating unit I2 with suitable pipe connections for selective modes of operation is shown sub stantially in Fig. 6 and Fig. 7. An in?uent pipe In Fig. 6 direct passages or passageways or transitions 88 or 89 respectively lead from the mixing chamber I5 over a submerged wall por tion 80 into the respective sections I3 and II of a ?occulating tank 9| de?ned by the side walls 92 and 33, the in?uent end 94, the e?luent end 95 having an e?iuent launder 96. A removable par tition 91 divides the launder into two sections 98 and 39. Eliluent pipes I00 and IOI lead from the 4 respective ends of the launder and have closure valves I02 and I03 respectively; A pair of sluice gates I04 and I05 control the in?uent from the mixing‘chamber I5 into the respective ?occulat ing sections I3 and I4. ‘ The control chamber I1 is connected through a passage I06 with an auxiliarychamber I01 from 20 which a connection I08 having valve or closure means I09 leads into ?occulating section I3, by passing the receiving chamber I6 and the mixing chamber I5. Through a valve I09a, a connection or pipe I I0 leads from the auxiliary chamber I01 to the clari?er_l0 (not shown in Fig. 6), and forms at II I a junction with the e?iuent pipe I00 from the ?occulator tank. - A corresponding connection or pipe I I2 from trol chamber I1, mentioned above. Another ‘gate, the control chamber I1 is provided with a valve 30 H3 and leads to a junction II4 with the ?occu valve or closure means 12 leads from the control chamber I1 into the receiving chamber I6 which . lator effluent pipe IOI and on to the second clari is separated through a'wall 13 from the mixing ?er II (not shown in Fig. 6). A connection II5 leads from the mixing chamber I5 to a point of chamber I5 (see Fig. 7). A passage 14 under neath the wall 13 leads into the mixing chamber junction II6 with the pipe IIO, a. valve II1 being 35 in which is provided a rotary mixing device 15 inserted in the connection II5. Another corre 10 leads through a. gate or valve 1I into the con_ such as a turbo-mixer shown in the further en larged detail section of Fig; 8. The agitator or device may comprise a vertical impeller shaft ‘150, is‘supported and ro tated'i'rom a drive or motor unit 16 shown to sponding connection II8 leads from the mixing chamber I5 to a point of junction HQ with the pipe II2, a valve 120 being inserted 'in the con nection II8. A pipe I2I having a gate or valve 40 I22 is shown to lead into the receiving chamber be mounted on beams or channel irons 11, (see I6, which pipe constitutes the connection carrying Fig. '7). At its lower end the vertical'shaft 15a over?ow from the clari?er I0 (not shown in carries a rotor or impeller 18, (see Fig. 8) which Fig. 6). _ . A horizontal sequence of transverse paddle-like 45 is shown to consist of a hub 18 carrying a disc 80, which has extending freely downwardly therefrom assemblies of paddle shafts I23 carries blades or radial impeller blades 8|. A'substantially annu paddles. I24 for the ?occulation units I3 and I4, lar stator 82 surrounds the'impeller 18, and which :to move or rotate about horizontal axes in re consists of a dished annular member 83, having‘ petitive paths. The shafts are shown to be driven freely extending therefrom a set of stator blades ‘by a set of chains I25, I26, I21 and corresponding‘ 50 84 to guide the liquid ejected from the impeller sprockets, and a motor or driving unit I28. blades. The annular dished member 83 is shown . < At I29 and I30 respectively, in Fig. 6 there are to be seated and anchored by bolts 85 upon a indicated pipe connections for the return or re ledge 86 protruding from the walls of the mixing . ‘circulation of clari?er sludge or the like. chamber 15. Itis noted that, with the exposed Numerals I3I and I32 in Fig. 7 indicate drain blades 8| and 84 extending freely in their respec-i connections for the ?occulation sections having‘ 55 ?ve directions, the movement of liquid through valves I33 and I34. the impeller device is eifected under relatively . In Fig. 9 the numerals I35 and I36 indicate the little lossof head on the one hand, while causing under?ow or sludge outlet connections from the a low pressure hydraulic boost on the other hand. respective‘ clari?ers I0 and II. I31 and I38 indi 80 With these impeller- and guide-blades being open a cate the respective over?ow launders of the or exposed as they are, the walls of the mixing clari?ers I0 and II. “ ‘ chamber in fact form the housing for this im peller- or low-lift pumping device which other- . Operation - wise is known of itself. In other words, the walls of the mixing chamber or section, which may also be called a rising channel, section or column, can be said to constitute in connectionwith the stator, the pressure chamber of the impeller de When operating the system with connections 65 established according to the diagram of Fig. 1 and for parallel operation of the clari?ers I0 and II, the gates or valves 12 and I09, I02 and I03, and vice; or it can be said that the stator 82 is associ ated with the chamber I5 in such a manner as age 22 continually enters‘ the control chamber I1‘ 470 H1 and I20 and I 22' are closed. Raw feed or sew through gate 1|, where it splits into portions one to form a constriction thereof for the pamage ' of which passes through passage I06 into the therethrough of the liquid being mixed and lifted. A pipe 81 terminating 'undemeath the impeller device serves for the introduction of conditioning auxiliary chamber I01 and from there through a gate I091: into the pipe or conduit IIO leading to feed the clari?er tank I0, the other portion of 2,187,966 the split up leaving the control chamber I ‘I, through gate I I3 to feed through pipe or conduit II2 the other clari?er tank _I I. The ?occulating unit is thus completely by-passed. Clari?er over ?ows 25 and 26 respectively may ?ow to a joint disposal. Clari?er under?ows or sludge dis subsequent ?occulation. Therefore, valves I094: and II3, I22, Ill and I20 and I22 are closed while ?ow is permitted to pass through valves 1| and ‘I2, gates I04 and I05, and valves I02 and I03. Consequently, _raw feed 31 may enter into the control chamber‘ I‘I, pass on into the receiving charges may also conjointly lead away. The chamber‘ I6, and through the submerged passage chemical dispensing arrangement I8 in this set v‘l4 via the mixing device ‘I5 into the mixing up is shown to be inactive although ‘its use is chamber I5. The dosing pipe 81 may now be 10 optional. The operating arrangement estab activedischarging a coagulating agent into the lished according to Fig. 1 may serve at times ?ow oi.’ liquid prior to entering the ?ash mixing ‘ when no special treatment is needed in the way phase of the mixer, such dosing being indicated of ?occulating a dosed or undosed sewage. by the arrows 46 in the dosing feed line I8a of The arrangement of _Fig. 1 may be modi?ed Fig. 3. Now the liquid is ready for e?ective ?oc-v 15 when it is desired to use a chemical coagulant culation of the suspended solids when the ?ow 15 and the mixing device ‘I5, by closing the valves splits to enter and pass through the' respective I09a and H3 andopening the valve ‘I2'as well as ?occulating sections I3 and I4 by way of open the valves Ill and I 20, while maintaining gates gates I 04 and I05. The removable partition 9‘! I04 and I05 towards the ?occulation zone closed, '20 and starting the mixer ‘I5 goingwhile adding the chemical through pipe 81 from the dispensing device I8 with the clari?er sludge lines 21 and 28 leading away. ‘ in the ‘overflow launder 96 of the ?occulating apparatus may now be eiIective to receive the 20 individual over?ows from the sections I3 and I4 in individual launder sections 98 and 99 so that the proper proportion of the total ?ow may reach - - When operating the system with connections 25 established according to diagram Fig. 2 for series operation of the clari?ers I0 and II, the gates I04 and I05 remain closed to block entrance into the ?occulating devices I2, I3; vvalve I I3 is closed and so are valves ‘I2 and Ill. Valves I02 and I03 Valve I22 in pipe I2I is now open 30 remain closed. and active together with valve I20 in pipe H8. Consequently, raw feed 29 may enter through open main gate ‘II into the control chamber I‘I, through passage I06 into the auxiliary chamber 35 I01, and through open gate I09a into the conduit I I0 through which it feeds theclari?er I0 which now becomes a primary clari?er. ~ Over?ow from this clari?er, brie?y called primary over?ow, en ters the conduit I2I which brings it through open 40 valve I22 into the receiving chamber l6 when a chemical coagulant or precipitation _agent may each respective clari?er I0 and II by way of pipes I00 and IOI through the open valves I 02 and I03 25 therein. . - _ The clari?er over?ows 42 and 43 may con jointly lead away to disposal. The clari?er un- der?ows 41 and 48, both containing chemically precipitated sludge, are in this case shown to be 30 led away to suitable disposal. _ In other words, the operating arrangement of .Fig. 3 affords increased purity of ‘clari?er over ?ow irrespective of under?ow or sludge treat ment. It is understood that with both clari?ers discharging dosed precipitate the character 01' the sludge thus obtained is not preferable for the process of. digestion. ‘ The operation according to Fig. 4 answers the demand for a highly puri?ed clari?er over?ow 40 and a clari?er sludge of such characteristics as to be‘ suited for the process of digestion. Conse be introduced through pipe 81 prior to entering the mixer ‘I5 in the mixing chamber I5. At this ‘quently, this ?owsheet suggests series operation stage the mixer effects a quick vigorous mixing of the clari?ers I0 and I I, coagulating and ?occu 45 or ?ash mixing while simultaneously inducing‘a lation of the secondary stage, and the use of low pressure pumping effect upon the liquid, undosed primary clari?er under?ow or sludge in which pressure compensates for the drop or head ‘the digesters I9 and 20, as well as digesting un loss incurred in the primary over?ow, and which dosed primary sludge ,‘together with dosed sec ondary sludge. will cause the liquid to enter pipe or conduit II8 50 with valve I20 open, and through conduit II2 will feed the clari?er II which now becomes the secondary clari?er. - The reason for the drop or head loss incurred through transfer from primary to secondary 55 clari?er is illustrated in Fig. 9_ which makes it clear that while both clari?er over?ows are on equal level in ‘the case of parallel operation, ‘the loss occurs. when changing to series operation and the primary over?ow drops into the over?ow launder of the primary. clari?er I0 from where it must be lifted again to the feed level of the sec ondary clari?er I I. A series ‘operation as described in connection with Fig. 2 is desirable for instance during cer 65 tain summer months when it is desired to apply‘ an economical and practical dosing method such as dosing the second stage, in order to effect a greater purity of the clari?er effluent in view of the low water of the natural streams into which the clari?ers may discharge and the greater putrefying tendencies concurrent with summer temperatures. ~ The diagram according to Fig. 3 again suggests parallel operation of the clari?ers I0 and U, ad 75 vancing over the setup oi’ Fig. 1 by the use of Consequently, the operating set up in Fig. 4 is 60 as follows: The valves H3 and ‘I2, and I09 are closed. Closed are also the valves II‘! and I20 leading from the mixing chamber I5, and the valve I02 in pipe I 00 leading from the ?occula tion apparatus launder 98. Open is the valve 55 I 09a from the auxiliary control chamber I01, open the valve I22 in pipe I 2| leading into the receiving chamber I6, and open are the gates I04 and I05 into the ?occulation tank. Open is the ?occulation apparatus discharge valve I03, lead 80 ing to the secondary clari?er II. The partition 91 is assumed to be removed from the ?occulation device launder 95. .’ Iri?uent 49 enters the control chamber I1, and through the auxiliary, chamber‘ III‘! with the valve I09'a opeuinto the pipe IIO, which carries the sewage to the primary clari?er I0 from which settled raw sludge becomes available for diges tion in the digesters I9 and 20 when led thereto through under?ow line 51 (see Fig. 4) . Over?ow 70 _from the primary clari?er passes through pipe I2 I into the receiving chamber I6, and on through the submerged passage ‘I4 via the mixer into the mixing chamber I 5. The mixer then of course exercises its additional function of boosting the 75 I a . 2,137,966 pressure head compensating for the drop incurred in the primary over?ow. ' Again, arrows 59 in the‘ dosing supply line I80 indicate that a ?occulant enters the liquid through pipe 81 below the mixer. The liquid thus conditioned splits to enter through gates I04 and I05 and ?ow through the ?occulating sections I 3 and I4 of the ?occulation tank 9| where the solids in the conditioned liquid undergo a process of ?occulation or coalescence 10 in preparation for a more effective subsequent 5 I claim: 1. A clari?cation system ior‘the removal of sus pended solids from ?owing liquids, and equipped for conditioning of the liquid preparatory to sedi mentation, which system comprises a raw liquid supply, a pair of clari?ers substantially arranged at an elevation for parallel operation, means for ‘selectively conducting liquid from said raw liquid sections ‘combines in the e?luent launder 96 with supply to said clari?ers so that under one set of selected conditions the clari?ers are arranged in parallel and so that under another set of selected conditions said clari?ers are arranged in series - the partition 91 removed, and throughconduit whereby they function-as associated primary and sedimentation. E?luent from both ?occulation I 0| and valve I03 reaches the terminal section 15 of the conduit I I2 and thus to feed the secondary clari?er I I from where over?ow 55' and sludge secondary clari?ers, said means comprising a mixing section arranged to receive liquid obtained 15 from said raw liquid supply and wherein the liquid‘ discharge 56 maybe disposed of in suitable-ways received therein can be subjected to a condition as by leading all or a desirable part thereof through the connection 56a into the digester I9 '20 to be digested therein together with the primary sludge from the line 51. ' ing operation, and a mixing device in said mixing sectiomwhich said device includes impeller means surrounded by the walls of said mixing section in 20 a manner to substantially form a.‘ housing for the The operation ‘according to Fig. 5- involves a further re?nement, in that it a?ords. secondary stage dosing for chemical precipitation, inde impeller means, said impeller means being effec tive to boost the hydraulic head of the liquid passing through said mixing section, said means pendent ?occulation. for each clari?er stage, as well as far-reaching clari?er sludge ultilization, in the digesters as well as for recirculation pur when arranged for series operation being ar 25 ranged to have said mixing chamber interposed poses, . Consequently, the set-up requires that valves 30 IOBa, H3 and ‘I2, II‘! and H8 and the gate I04 between the primary and the secondary clari?er to e?ect e?‘icient mixing of any added condition ing material and of the primary clari?er over?ow at a place ahead of the secondary clari?er, said 30 be closed, while valves I09, I02, I22, the gate I05, mixing device also being effective to supply su?‘i and valve I03 be open. Eilluent 60 then passes through the control chamber I1 and the auxiliary chamber I01, and through valve I05 via the by cient hydraulic head to ensure the transfer of liquid from the primary to the secondary clari?er. 2. A clari?cation system according to claim 1, 35 pass conduit I08 through the ?rst ?occulation. characterized by the including of an agitating 35 ~10 section I3 where solids are ?occulated and made section for effecting ?occulation of the solids in settleable by .the peculiar agitation in?uence of the conditioned liquid, and by the further fact the ?occulating paddles I24. Assuming the re ,(a) that said means when selectively set for parallel operation of the clari?ers have controls movable partition 91 to be' inserted in- the ?occu lation device eiiluent launder 96, the liquid treated for selectively conducting the liquid from the 40 in the ?occulation section I3 may leave through point of raw liquid supply consecutively through the launder section 98 via the e?luent pipe I00 the mixing section and past the mixing device and and valve I02, in order to feed the primary clari _ thence through said ?occulating section, and ?er I 0 after passing through the terminal section (b) that there are controls whereby the volume of the pipe conduit IIO. ' ' = of the ?occulated liquid is split for subsequent Over?ow 64 from‘ the primary clari?er I0 passes parallel treatment of the component volumes in said clarifiers. , by way of pipe l2! and valve I22 into the receiv 3. A clarification‘system according to claim 1, ing chamber IS in preparation for its secondary ‘coagulation and sedimentation step‘. That is to characterized by the addition of an‘ agitating sec tion to effect ?occulation of the solids in the say, the liquid after passing through the sub merged passage ‘I4 may now again be dosed with liquid, and by ‘the fact that with the clari?ers a chemical coagulant through the dosing pipe 81, " operating in series the agitating section is oper atively interposed'in the flow connection leading from the mixing section to the secondary clari?er, 4_ with arrows in the dosing feed line I 8a indicating that the line is active in this respect. The dosed liquid by reason of the boosting e?ect of the mixer ‘I5 is drawn into the mixing chamber l5, the boosting pressure‘being su?icient to insure compensation of the head loss incurred in the primary clari?er over?ow and to cause the ?ow of liquid to pass through open gate I05 and through the second ?occulation section I4 and to reach the secondary clari?er I I’ by way of effluent pipe I 0| and the terminal section of the pipe “2 (not shown in Fig. 6). Over?ow from the sec ondary clari?er I I may leave through 61 to suit able disposal. Under?ow or sludge from the sec ondary clari?er may advantageously be utilized for recirculation or redistribution within‘ the plant as by reintroducing it into the control chamber IT or the auxiliary chamber I01, via the pipes I29 and I30 respectively. ' ‘ A divisional patent application has been ?led ‘' by me on December '18, 1937, covering subject: matter carved from this patent, and by the further fact that operating means are providedfor selectively by-passing said agitating section. 4. A'clari?cation system according to claim 1, ‘characterized by the addition of an agitating sec tion to effect ?occulation of the solids in the 60 liquid, and by the fact that with the clari?ers operating in series the agitating section is oper atively interposed in; the ?ow connection leading from the mixing section to the secondary clari?er, and by the further fact that operating means are 65 provided for selectively by-passing said agitating section and said mixing section. I 5. A clari?cation system according to claim 1, characterized by the addition of an agitating sec tion for the purpose of ?occulating the solids in 70 the liquid, which section comprises a pair of ?oc ' culating units adapted for parallel operation, and also characterized by the fact that connections and controls therefor are provided, selectively operable to include one ?occulating unit in the 75 6 2,137,968 ?ow connection between the raw liquid supply and the primary _clari?er,‘and to include the second ?occulating unit in the ?ow connection between the mixing section and the secondary‘ clari?er. 6. A liquid clari?cation plant, comprising a raw liquid supply; a clarifying section, including a pair of clari?ers; a liquid conditioning and ?oc culating section, including a ?occulating unit and 10 an impeller mixer having hydraulic lifting power, and closure means selectively operable between ‘?occulating unit and mixer; a feed ‘connection from the ?occulating unit to each clarl?er, and individual selectively operable closure means for 15 each connection; a by-pass: connection between said liquid supply and each clari?er, and closure means associated therewith selectively operable to eliminate the ?occulating unit; an over?ow return conduit between one clari?er and said 25 wardly through said mixing section and adapted to effect combined mixing and hydraulic lifting of 10 the liquid passing through the apparatus, said rotor element comprising a substantially hori zontally-extending rotary disc member and radial _ blades extending downwardly therefrom, said stator comprising a substantially horizontally. 15_ extending. annulus and radial blades rising there from; said impeller device adapted to have a sub merged pressure discharge and to be effective to .maintain in said mixing section a zone of rela tively-increased hydraulic head at the delivery 20 means associated with said return conduit; all of said connections and closure means selectively operable in such coordination as to effect changes of operation substantially as described. side of the device as compared with a relatively lower hydraulic head at the inlet side thereof. 13. In a liquid treatment apparatus having a '7. A liquid clari?cation plant according to for, arranged between the raw liquid supply and the mixer. liquid supply, and having a liquid mixing section and a subsequent treatment section to receive 25 liquid therefrom, said section adapted for sub the ?occulating unit for selectively eliminating ' f 8. A liquid clari?cation plant according to claim 6, in which the-raw liquid supply comprises a control chamber ahead of the mixer for selec 35 including a rotor and a stator element interposed in the path of the liquid which must pass up liquid supply, and selectively operable closure claim 6, with the addition of a by-pass connec tion and selectively operable closure means there 30 and in horizontal sequence to the latter a subse- ’ quent treatment section to receive liquid there from, said mixing adapted for substantially up ward ?ow therethrough of said liquid and con tinued ?ow by way of hydraulic communication into said ?occulating section; an impeller device tively directing feed to desired points of the plant. 9.v A liquid clari?cation plant according to claim '6, in which the raw liquid supplycomprises a control chamber ahead of the mixer for selec tively directing feed to desired points of the plant, and with the addition of an intermediate receiv stantially upward ?ow therethrough of said liquid ' and continued flow by way of hydraulic com munication into said treatment section; an im peller device interposed in the upward path of 30 the liquid through said mixing section and adapt ed to have a submerged pressure discharge and ' to effect combined mixing and hydraulic lifting of the liquid passing through the unit, said impeller device comprising a rotor revolving about a sub 35 stantially vertical axis, and a stator surrounding the same and which is associated with the sur rounding walls of said rising portion so as to form a constriction thereof for the passage there through of the liquid being mixed and lifted, said and the mixer and adapted for receiving over?ow impeller device, by its operation, being effective _ through said over?ow return conduit from said ,to maintain in said mixing section a zone of rela tively-increased hydraulic head at the delivery 10. A liquid clari?cation plant according to side of the device as compared with a. relatively lower hydraulic head at the opposite side thereof. 45 claim 6, in which the ?occulating unit comprises‘ 14. In a liquid clari?cation system, an appara a.pair of independently operable units, and with tus combination which comprises a liquid dis the addition of individual closure means selec tributlng section, a liquid supply therefor, a liquid - tively operable between said mixer and the re dosing section, a controlled outlet connection spective ?occulating units. _ leading from said distributing section, a con-, 11. A liquid treatment apparatus, which com 40 ing chamberinterconnecting the control chamber clari?er. 50 ~ ‘ _ - trolled connection between said distributing sec tion and said dosing section, a pumping pressure section, a pumping device between said dosing combined mixing and hydraulic pressure-impart ing device therein adapted to have a submerged section and said pressure section and through ‘which there exists hydraulic communication be 55 pressure discharge and which is effective to main tain above said device in the conditioning section. tween the pumping and the dosing sections, a a zone of relatively increased pressure head; and controlled outlet connection from said pumping a subsequent treatment section in ‘horizontal pressure section, and a controlled separate inlet sequence to said conditioning section and adapted connection as distinguished from said controlled . prises a mixing section adapted to have liquid ?ow substantially upward therethrough, a rotary 60 to have said liquid ?ow thereto by way of direct hydraulic communication. _ ' ' 12. In a liquid treatment apparatus having a liquid supply and having a liquid mixing section, connection between the distributing section‘ and the dosing section, leading into said dosing - section. REiWIIl-E s. RANKIN.