ROTATING BIOLOGICAL CONFACTOR

Abstract: Rotating Biological Contractor constituted by filter-body segments (3) arranged between spokes (1) on a common shaft or axel (2). The filter-body segments (3) are pressed inwards towards each other by V-shaped holding members (5) extending longitudinally between spokes. Through adjustment the V-shaped holding members can be given different radial locations and pressing forces. The flow through the RBC unit is controlled by the design in order to avoid negative effects like anaerobic conditions or settling of sludge. The RBC segments or sections (3) are given a triangular cross section so that a saw-tooth like periphery is obtained.

Description: ROTATINGBIOLOGICALCONFACTOR The invention relates to an improvment in Rotating Bio¬ logical Contactor (RBC) process and design. This RBC is a biological treatment unit of the kind that comprises several segment-like RBC material bodies, which together with a sup- porting structure are assembled to a RBC. Wastewater to be treated flows through a tank in which the RBC is immersed. These RBC's are in general arranged so that waste water can penetrate radially and. circumferencely in the rotor an conse¬ quently the flow to and from the rotor is essentially perpen- dicular to the axis of the rotor. Although those known RBC's of the above kind have good performance, they are rather expensive due to their construc¬ tion and they are furthermore complicated to service as the tough conditions, under which they are used, cause difficul- ties in dismantling. A further negative point with these- BC's is that due to their design and construction it has been im¬ possible to use the latest developments in RBC material as these after some time are slightly compressed due to the high loads of the sludge and thus would work loose in the RBC. With known RBC's the tightning after some time for the above rea¬ sons is difficult. If the RBC segments as above are not carefully and tight¬ ly fastened, initially small movement of the segments will gradually increase and finally the RBC segment material will crack or collaps. It is th object of the invention to overcome the above difficulties and give an always easily assembled and disas¬ sembled RBC containing only easily fabricated parts. The above objective is in accordance with the invention achieved by subjecting the different segments of the RBC to an adjustable pressure radially inwards pressing the diffe¬ rent segments sideways against each other. This pressure is obtained by elongate members with extending over the entire length of the top of the segment and pressing radially aga- inst this. Together with the members e.g levers are used in order to obtain the necessary pressure against the body segments. Locking as well as location of the levers ca be accomplished with the aid of pins, thus avoiding problem with corrosion of screws and bolts, and simplifying readjus ment of the segments, but of cours bolts can be used also i order to secure the V-shaped members in a pressure giving l cation. Further features and advantages with the invention are apparent from the following description of a reffered embo¬ diment, with reference to the.drawings. In the drawings fig. shows a RBC in accordance with the invention seen from one end or axially submerged in a tank, fig. 2 an elevated view of the RBC of fig. 1 , fig. 3 examples of fastening mechanis for the segments and fig. 4 and 5 in a large scale one fast ning method. In fig. 1 the RBC is shown submerged in a tank 11 in wh ch the water level 12 have been indicated. The rotor is in tended to rotate counter-clockwise in order to give a certa turbulence, close to the bottom of the tank in order to pre¬ vent sedimentation there. A further object that is achieved is that the water on rotation of the RBC is proppelled in to the segments. This is the result of the segments having a more triangular shape than segment alike. This also has i advantages in connection with packing, storing and transpor¬ tation of the segments prior to assembly. As can be seen fr fig- 3 the segments do not extend fully in to the shaft 2 o the RBC. This space between the shaft 2 and the RBC materia sections 3 improve water transportation and the dislodging of a sludge. Also this prevents the RBC segments 3 from bei subjected to a cracking pressure from the shaft. Instead th segments or sections 3 are pressed inwards against radial sp kes 1 that have a T-cross section. In order to improve the guiding of the spokes these may further be provided with fl members for increasing the supporting surface of the spokes and of course the T-shaped spokes may be exchanged for flat ones provided with a sufficient amount of flat members givi the sections their angular guidance. In the above manner th RBC sections or segments are subjected to forces in a way that they stand well. O As has previously indicated the RBC segments or sections 3 are pressed inwards and fig. 2-5 two ways of doing this is indicated. In fig.4 the pressure radially inwards on the RBC section 3 is exerted by an elongate member 5 that has a V- shaped cross-section and that extends between two spokes axi- ally along the RBC. This V-shaped member 5 may be perforated one way or the other in order to allow water to stream thro-- 1 , ugh it. These V-shaped members are not themselves directly faste- ned in the spokes, instead a' lever 6 (fig. 4 and 5) extend through a hole in the spoke 1 and after the incertion of the ends of the lever 6 which has a middle part that extends over the lenght of the V-shaped member this is pressed downwards towards the V-shaped member thus pressing this securely aga- inst the RBC sections 3. In order to retain the lever in this biasing position a bolt 13 together with the clamping means 14 securely holds the lever against the V-shaped elongate member 6. The spokes may be provided with several holes as has been indicated at 15 in fig. 4, this in order to allow for ajustment when the RBC segments after some time have be¬ come compressed. As the RBC sections 3 during rotation alternatively are subjected to reguly inwards and outwards directed gravita¬ tional forces it is important that the pressure inwards on the V-shaped member is sufficient to overcome the forces ra¬ dially outwards in order not to have the segments moving forth and back which will result in great wear and finally wastage of these. In order to get an optimal use of the material an easy storing and cutting the inner ends of the segments are pre- fereably cut parallell to the outer sides. Thid also dis- minish the risk of anaerobic conditions in the center of the RBC and also improves the above mentioned optimum material use on fabrication of the segments. As mentioned above one important drawback of previous ex¬ isting RBC's are the tendency of settling of dislodged sludge on the bottom of the tank, resulting in anaerobic condition and sludge floatation which in turn may clog the the RBC a- - EAcT OMPI " terial. The saw-tooth, form of the segment disminish this bu it may further be improved by arranging elongate V-shaped members 16 between the end of the spokes, these V-shaped me bers having an edge either in the rotational direction or o • posite this, the direction being established by optimum tur bulence conditions which may differ depending on the size o the saw-tooth. These members.16 may also be provided in ord to improve the propelling of the water into the sections 3. In fig. 3 a different alternative of fastening means i shown. The V-shaped members 17 is at their ends fastened in side plates 18 that are slideable along the spokes radially The spokes and/or the sideplates 18 can be provided with elongate holes to allow for different locking positions or several holes. Fastening may in the first case be by means of bolts and in the second by means of bolts or in one way o the other locked pins. At the outer perifery- the side plate may be joined by a further member with the purpose of direc ting the waterflow in through the RBC-segments. In order to obtain the pressure inwards on the V-shaped members 17 leve can of course be used in the same way as in fig. 4 and 5 bu it is also possible only to use the levers on mounting and dismounting of the RBC segments and having the position loc ked by the means of pins or bolts. The tendency towards anaerobic conditions in the center part of the previously known RBC's, close to the shaft wher the exchange of oxygen is most difficult is satisfacturaly overcome by the arrangement according to the invention. The water is thus directed inwards the center of the RBC and th water may then pass through the above mentioned space betwe shaft and RBC segments and in this way can the exchange of oxygen in the center part of the center part of the RBC be greatly improved. With the arrangement in accordance with the invention i is further possible to use RBC materials with various speci fie areas along the shaft and it is further possible to use previously useable materials and it is further easy to ex¬ change the RBC segments and to retension segments that have worked lose. Totaly the invention results in a far more use ful and economic RBC rotor than those previouslλ- used. OM

Claims: C l a i m s 1. Rotating biological Contactor constituted by filter- body segments or sections (3) allowing radial and peripheral water flow, c a r a c t e r i z e d i n that the filter- body segments are radially pressed inwards and against each other by members extending longitudinally over the lenght of the sections and that the sections (3) are essentially tri¬ angular to their cross section and give saw-tooth like outer periphery. t 2. Rotating Biological Contactor according to claim 1, c a r a c t e r i z e d i n that the filter-body segments (3) do not extend fully in to the shaft (2) of the RBC, but leave an open space towards the centre of the rotor in order to improve water flow and oxygen exchange. 3. Rotating Biological Contactor according to claim 1 or 2, c a r a c t e r i z e d i n that it further comprises longitudinal members at the outer periphery shaped to create a flow through the RBC from the periphery towards the centre in order to avoid anaerobic conditions there. 4. Rotating Biological Contactor according to one of the above claims, c a r a c t e r i z e d i n that the holding members (5) that press the filter-body sections (3) inwards are pressed inwards on mounting by -levers (6) . 5. Rotatiing Biological Contactor according to claim 4, c. a r a c t e r i z e d i n that the lever (6) is locked in a position pressing the member (5) against the section (3) by means of the bolt (13) and a bracket (14) fastened in the elongate member (5) . 6. Rotating Biological Contactor according to one of the above claims, c a r a c t e r i z e d i n that sections have various specific area along the shaft in order to opti¬ mize the process. -- ύEAtF- OMPI

Inventors: HALLEN L
Applicants: HALLEN L, NORDISKA VATTENPROJEKT AB NOVA, NORDISKA VATTENPROJEKT AB
Application year: 1980
Main classification: C02F3
IPC codes: C02F3