Waste water purifying plant
This is a continuation of application Ser. No. 839,498, filed Oct. 5, 1977 now abandoned. 
    
    
     The invention refers to a mechanico-biological waste water purifying plant having a trough and at least one partly immersed rotatable body arranged therein and having a stack of discs which are partially immersed in the waste water. A shaft projecting at the ends beyond the stack of discs supports the body rotatably in bearings. Mechanico-biological waste water purifying plants of this kind are well known. 
     In one such known purifying plant (see Swiss Patent No. 441,140) the partially immersed body is arranged in fixed bearings in the trough. For maintenance and repair work it is necessary to dismantle at least the bearings and partially strip the body too. Maintenance and repair work thereby becomes not only timewasting but as a result costly. 
     From Swiss Patent No. 537,340 a mechanico-biological waste water purifying plant is known in which the rotatable body consists of a stack of discs where the discs run in a helix. The individual helical surfaces are formed of discs in the shape of sectors of a circle overlapping one another, which are arranged in a guide-groove running helically in the hub. The discs of adjacent helical surfaces are kept apart by means of spacer-members. The helical surfaces are further braced together by means of a number of strain members arranged parallel with the hub. This body likewise has a shaft projecting at the ends beyond the stack of discs, by means of which the body can be supported rotatably in bearings. With this body too no precautions are taken to bring about simple supporting of the shaft. The shafts must be arranged in closed bearings. This leads not only to complicated mounting of the body as, for maintenance and repair work, troublesome and costly work of dismantling is likewise necessary. This kind of support of the body also does not allow a number of bodies to be coupled together simply. 
     The body of the known purifying plant is moreover constructed in a rather complicated way since it needs, for guidance of the discs, hubs which are provided with guide-grooves running helically. With this form of body close limits are set to its diameter for reasons of rigidity. 
     According to the invention a mechanico-biological waste water purifying plant has a trough and at least one partially immersable rotatable body arranged therein, the body having a stack of discs which are partially immersed in waste water in the trough, and a shaft projecting at its ends beyond the stack of discs and supported rotatably in bearings, each of which has at least two bearing rollers upon which the ends of the shaft are positioned to be liftable upwards freely. 
     Because each of the bearings exhibits at least two bearings rollers upon which the ends of the shaft rest so that they can freely be lifted upwards, not only is mounting of the body made considerably easier but also its dismounting for maintenance and repair work. This construction also enables the bearings to be constructed so that the adjacent ends of two bodies or of one body and an auxiliary unit can be supported on one bearing and coupled together at that point too. This confers the advantage that such bodies may be manufactured in standardized sizes and, depending upon the necessary capacity of a purifying plant, can be combined in any required number with other bodies. 
    
    
     One example of a plant according to the invention will now be described in greater detail below with reference to the accompanying drawings, in which: 
     FIG. 1 shows a mechanico-biological waste water purifying plant in side elevation and with the sidewall cut away; 
     FIG. 2 shows the purifying plant of FIG. 1 in section along II--II in FIG. 1; 
     FIG. 3 shows a bearing of the purifying plant in section along III--III in FIG. 1, on a larger scale; 
     FIG. 4 shows the bearing of FIG. 3 in section along IV--IV in FIG. 3, on a larger scale; 
     FIG. 5 shows a rotatable body of the purifying plant of FIG. 1, partially sectioned and on a larger scale; 
     FIG. 6 shows the rotatable body of FIG. 5 in elevation one one end face component on a smaller scale; 
     FIG. 7 shows a plug-in-together spacer-member for connection and spacing of two discs of the rotatable body in section and on a larger scale; 
     FIG. 8 shows the spacer-member of FIG. 7 in section and in elevation on the plug-in part; and, 
     FIG. 9 shows a portion of a rotatable body with the stack or discs in parallel. 
    
    
     FIGS. 1 and 2 show a mechanico-biological waste water purifying plant which has a trough 2 in which two partially immersible rotatable bodies 4 and a paddle 6 are supported rotatably in bearings 8. The bearings 8, arranged on bearing pedestals 10, each have two bearing rollers 12 upon which the ends 14 and 16 of the shafts 18 of the body 4 and of the paddle 6 rest, so that they can be lifted upwards freely. The bearings 8 are further so constructed that adjacent shaft ends 14, 16 which are coupled together rest on a common bearing 8 as is described in further detail below. One of the bodies 4 carries a gear rim 20 with which engages a driving motor 22. The waste water to be purified flows via an inlet 24 into the trough. The biologically pure waste water flows away via a discharge 26. A duckboard 28 serves to cover over the trough. 
     As shown in FIG. 1 the purifying plant contains two bodies 4 constructed to a standard size, and a paddle 6. The paddle acts on the one hand as a filler body for keeping free a spare space for a further dip-drip body in the event that the capacity of the purifying plant has to be increased and the other hand, by its revolving action, it prolongs the residence time of the waste water in the trough and hence increases the purifying action. Apart from this the paddle prevents precipitation of the sludge. 
     The paddle could alternatively be arranged between two bodies, thereby subdividing the purifying plant into two stages between which a prolonged pause is caused by the paddle. Hence with uniform components purifying plants of any desired size and kind can be produced, and in particular the possibility is also provided of subsequent expansion of the purifying plant. 
     In the embodiment shown the discs of a stack of discs of the body 4 are not parallel with one another but are connected together into a helical surface as is further explained in greater detail in particular with the aid of FIG. 5. Correspondingly the flow through the bodies and hence the purifying plant is in the axial direction. It is however also possible to arrange the discs of the stack of discs in parallel and to pass the flow through the bodies and the purifying plant transversely to the axis of the bodies. Such a construction is shown in FIG. 9. 
     FIGS. 3 and 4 show details of construction of the bearings 8 and shaft ends 14, 16 of the bodies 4 and the paddle 6 respectively. The shaft ends exhibit radially projecting shaft flanges 30 the peripheral surface 32 of which serves as bearing surface for the bearing rollers 12. The shaft flanges 30 contain two driving-pins 34 lying diametrically opposite one another and, offset by 90°, two driving-openings 36 also lying diametrically opposite one another. The driving pins consist of a bush 38 which is bolted to the shaft flange 30 by means of a bolt 40 and a nut 42. The shaft flanges 30 of adjacent shaft ends 14, 16 may in this way be coupled together. 
     The bearing 8, arranged on a bearing pedestal 10, includes a forklike bearing housing 44 open at the top for receiving one or two shaft ends 14, 16 so that these may be introduced from above into the bearing. The bearing rollers 12 are supported on shafts 46 the outer parts 48 of which are introduced into slots 50, 52 in the bearing housing 44 and secured against slipping out by means of stops 54. These slots 50 and 52 for the two bearing rollers 12 of one bearing point obliquely upwards and away from one another. Preferably the slots slope at an angle of approximately 45° to the horizontal. The outer parts 48 of the shaft 46 are preferably made flat and exhibit a rectangular cross-section. This enables a broad bearing surface for the outer parts 48 in the slots 50 and 52 and a simple form of the stops 54 projecting into the slots 50 and 52. The slots 50 and 52 in the region of the stops 54 are kept wide enough for the outer parts 48 after lifting over the stops 54 to be able to be slid in and out of the slots. The bearing housing 44 exhibits in the region of the bearing rollers 12 supporting ears 56 which are used for supporting the shaft ends 14, 16 when the bearing rollers 12 are removed or worn out. Again, guides 57, arranged opposite one another at axis height on the bearing housing 44, cooperate with the shaft flanges 30, facilitate their introduction into the bearings and oppose any possible jumping out of the shaft flanges out of the bearing rollers. 
     The bearing rollers 12 have each a peripheral groove 58 for receiving a shaft flange or two adjacent like shaft flanges 30. The peripheral groove guarantees maintenance of the shaft flanges 30 in their axial positions. The sidefaces 60 of the peripheral groove 58 are preferably bevelled in order to facilitate introduction of the shaft flanges. 
     The bearing rollers 12 are preferably annular and exhibit on the inside of them a bearing bush 62 which slides on a bearing ring 64 on the shaft 46. The bearing ring 64 is divided across and exhibits collars 66 overlapping the bearing bush 62 on both sides. Each part 64a, 64b of the bearing ring is connected to the shaft 46 by means of screws 67 so that the bearing roller 12 is guided laterally by its bearing bush 62. On both sides of the bearing seals 70 are arranged to seal off the sliding surfaces, being preferably made as lip-seals. These seals are advantageously fastened to the bearing ring 64 and overlap with their lips 72 the endfaces of the bearing bush 62 and part of the endface of the bearing roller 12. The latter includes axially projecting extensions 74 which cover over the seals to protect them. 
     The shaft 46 of the bearing roller 12 consists of a cylinder barrel 76 into which is welded a flat bar 78 which forms the outer parts 48 of the shaft. 
     This construction of the bearing rollers is extraodinarily robust and hence little prone to trouble. For maintenance and repair work such a bearing roller can also be simply replaced by raising the body be means of a hoist far enough for the outer parts 48 of the shaft 46 to be able to be lifted over the stops 54 and moved upwards out of the slots 50,52. A new bearing roller 12 can be quickly inserted in the reverse sequence. Between the exchange of the bearing rollers 12 the body may be rested with its shaft ends 14, 16 on the supporting ears 56. 
     FIGS. 5 to 8 show details of the construction of a body 4. Such a body includes lateral endface components 80,82 which look like a spoked wheel and include the shaft ends 14, 16 with the shaft flanges 30. The shaft ends 14, 16 are connected together by a connecting tube 84. 
     Between the endface components 80, 82 is arranged the stack 86 of discs 88, the individual discs being kept at pitch by spacer means 90 and connected with the endface components by means of strain members 92. In the present example the discs of the stack of discs form a helical surface i.e., one disc 88 continues without a break into the next disc. Correspondingly the endface components too are helical and exhibit a break 94 at which one disc continues into the disc of the adjoining helical surface. As may be seen in particular from FIGS. 6 and 7 the discs consist of two layers of individual sectorlike disc parts 100, the disc parts of the one layer being preferably offset with respect to the disc parts of the other layer by half the sector angle of the disc parts. This construction imparts high strength to the disc part so that rotatable bodies of considerable diameter can be produced. These sectorlike disc parts may exhibit, for example, a sector angle of 34.03° so that 10.5 disc parts are necessary for the formation of one layer of one disc of the stack of discs. 
     The strength of the stack 86 of discs can be improved if besides the strain members 92 further spacer members 102 are arranged which can be plugged into one another. A spacer member 102 of this kind exhibits at one side a plug-in portion 106 which is plugged into an opening 104 in a disc 88 and at the other side a cap portion 108 which grips over the plug-in portion of an adjacent spacer member. The plug-in portion 106 includes, viewed from the endface, an external face 110 tapering out, which continues into a face 112 tapering in, which leads into a recess 114 which exhibits an abutment face 116 for the disc 88. The cap portion 108 has an abutment face 118 at the end for the disc 88, which continues into an external oblique face 120 which cooperates with the tapering-in face 112 of the plug-in portion 106 of the adjacent spacer member 102 in such a way that the disc 88 is clamped in between the abutment faces 116,118 of the plug-in portion 106 and the cap portion 108. 
     The plug-in-together spacer member 102 is, in the present example, made as a hollow cylinder and has a slit 122 continuous along its whole length. Since it moreover consists of spring steel the spacer member is springy, so that the cap portion 108 is pulled by means of its oblique face 120 over the tapering-in face 112 of the plug-in portion 106 against the disc 88. In contrast to the embodiment illustrated it is also possible to make the space member with a slit merely in the plug-in portion so that only this portion is springy, whilst the cap portion 108 is rigid. It is also possible to produce the spacer member from plastics, which may be adequately elastic, so that complete or partial slitting may be waived. By means of these plug-in spacer members 102 the discs can also be connected and kept at pitch where no strain member 92 is provided. 
     By means of this method of construction it is possible to produce satisfactorily rigid rotatable bodies of large diameter, for example, of 3 to 4 metres. The bodies can be prefabricated factorywise and mounted and exchanged as a whole.