WATER CLARIFIER AND SEWAGE TREATMENT DEVICE

Abstract: The water clarifier and sewage treatment device compri­ ses a rectangular tank (12) wherein substantially all the wor­ king parts are made of non-metallic material. The system includes a telescoping non-metallic drive shaft (32) connected to sprockets (28, 30) for driving chains (36, 38) with the sprok­ kets (28, 30, 34) being mounted to non-metallic stub posts (33, 37, 35) which are mounted to the side walls (14) of the tank (12).

Description: The invention relates to a water clarifier and sewage treatment device comprising a rectangular tank including a floor, a pair of side walls and a pair of end walls, spindles secured to the side walls, sprockets received on said spindles, a pair of chains meshing with the sprockets, a pair of which sprockets is connected by a drive shaft and driven by drive means while the other ones are idler sprockets, and a plurality of flight members secured to the chains for scraping the floor of the tank. Water and sewage treatment systems are well known. For more than 50 years, rectangular clarifiers (rectangular concrete tanks) have been used in the treatment and purification of sewage, sewer drain, and drinking water. They are used to remove those materials which are either not biodegradable or cannot be chemically treated during the water purification process. Typically, these clarifiers have been referred to as either primary (4-shaft systems) or secondary clarifiers, (3-shaft systems). A primary clarifier removes: 1) non-biodegradable solids (i.e. grit) that precipitate to the bottom of the tank where they are collected, and 2) scum which is collected from the top surface of the water. A secondary clarifier removes the non-biodegradable solids that precipitate to the bottom of the tank that have not been removed during primary clarification. This can be accomplished in the following manner: Systems include motor-driven sprockets which move two parallel chains which have flight members attached thereto. The flight members scrape the floor of rectangular clarifier tank in one direction, gathering all solid waste materials which have fallen to the floor of the tank and moving them to a cross collector located at one end of rectangular tank. The solids collected in the cross collector are then pumped to a location for additional treatment or final disposal. Both primary and secondary clarifiers perform this function. Primary systems perform an additional function. Waste materials which are not biodegradable and have specific gravity less than water (i.e., soap or oils) float to the top and sit on surface of water. This solution is commonly referred to as scum. 4-shaft systems have flights protruding half out of the water, running in the opposite direction (from those flights moving solids on the bottom of tank), supported on return rails. The flights move in one direction on top surface of water and push this waste into an element called a scum collector, where these waste materials are removed to a location for additional treatment and final disposal. A number of different stages are generally used in the overall treatment system. Historically, all mechanical components in rectangular clarification systems were metallic, driving first-grade redwood flights. These components typically consisted of steel drive and idler shafts connected to babitted steel wall bearings which are set in steel wall brackets. Steel chain to which wooden flights are attached are driven by steel sprockets. All return rails attaching rail brackets and floor rails are made from steel. Wear shoes have also been made from steel. The chemicals and oxygen used to treat the water and the general water environment cause severe corrosion of all steel components. It is common for the steel components to be porous, allowing grit and scale to pack in the surface of metal parts. The combined effects of these problems cause severely accelerated wear of all metallic components. Steel drive and steel idler shafts become permanently stuck in steel wall bearings and will not rotate, which causes system failures. Metallic parts are energy consuming and have a high weight. It is the object of the invention to create a water clarifier and sewage treatment device of the generic kind which is non-corrosive and energy efficient and which has light weight, costs less to install or repair, and is superior in wear and performance. This object is obtained with the water clarifier and sewage treatment device of the generic kind in that according to the invention the drive shaft consists of telescoping tubular members made of plastic material and in that the spindles are plastic stub posts. In accordance with the present invention,the water and sewage treatment system comprises a rectangular tank in substantially all plastic parts including stub posts having spindles disposed on bearings. The stub posts are connected to sidewalls of the tank with spindles extending into drive shafts and sprockets. A drive shaft between two drive sprockets comprise telescoping members to facilitate assembly and disassembly of parts within the system.On sprockets two strands of chain are moved through the turning of drive shaft and free rotation of idler sprockets on stub posts. Advantageously, the drive shaft comprises three telescoping tubular plastic members including two end tubular members and an intermediate tubular member fitting into the end tubular members and connected therewith, which end tubular members extend through said pair of sprockets and are connected to move with said sprockets. The above-mentioned three plastic members may consist of glass fibre-reinforced tube sections. Preferably, each end tubular member is connected with the intermediate tube section by a plastic tube interlock key assembly comprising a locking bar extending through openings in the end tubular member and the intermediate tubular member and held in place by plastic fastening means. Further, a plastic shaft collar may be connected around the intermediate tubular member in contact with each end tubular member. It is convenient that each stub post for the sprockets driven by the drive shaft comprises a plastic main body secured to the side wall, a plastic shaft extending from the main body, a plastic sleeve secured to said plastic shaft, a plastic bearing element surrounding said plastic sleeve and plastic means for connecting the respective end tubular member of the drive shaft with said plastic bearing element and the sprocket to freely ride as a unit on tee plastic sleeve. The above-mentioned plastic sleeve can be secured to said plastic shaft by means of non-metallic set screws. Further, the said means for connecting the respective end tubular member of the drive shaft with said plastic bearing element can comprise a pin element. It is advantageous that each stub post for the idler sprockets comprises a plastic main body secured to the side wall, a plastic shaft extending from the main body, a plastic sleeve surrounding the plastic shaft and fixed thereto by a plastic pin, the idler sprocket being supported to rotate freely on said plastic sleeve. Conveniently track members mounted in the floor of the tank for engagement with the flight members, the flight members, the sprockets and the chains are plastic elements. Preferably, a bull sprocket driven by the chain of the drive means is mounted around the end tubular member of the drive shaft and fixed thereon by a key extending through the end tubular member and the plastic bearing element. The elements of the water clarifier and sewage treatment device according to the invention are made of non-metallic material, such as plastics including polyamides as Nylon-6 which have high wear properties. The completely plastic sludge collection system is designed to eliminate corrosion problems and dramatically reduce installation and maintenance costs in rectangular water clarifier and sewage treatment settling tanks. The system according to the invention provides at least double the service life of conventional cast and malleable iron components. Engineered plastic chains, sprockets and scraper flights have proved to be the ideal replacements for metallic parts in hundreds of settling tank installations throughout the country. The system made of plastic products provides an entire sludge collection system that is totally integrated to yield maximum life and cost efficiency. In addition the system is made simpler by designing out the need for idler sprocket shafts in either new or retrofit installations. While prior art systems have included some non-metallic products, the use of plastic collector chain drive and idler sprockets in combination with plastic stub shaft spindle and bearing assemblies and a tubular drive shaft assembly have not been used. The stub posts and drive shafts have had to be redesigned from their original metal counterparts when plastics, such as Nylon-6, are used. Made of high strength, light weight cast Nylon-6, the one-piece stub shaft spindles are stud-mounted to the tank walls at each sprocket location in place of cast iron wall bearing and shaft housings. Babitted or bronze bearings have been replaced with tubular cast nylon bearings secured to the spindles with a non-metallic key. Free-turning idler sprockets are held in place with a cast nylon retainer plate fastened to the stub shaft spindle with a stainless steel bolt, while drive sprockets are attached to their shafts with a keyway and key, and set screws. The drive shaft is made from specially formulated glass fiber-reinforced polyester tube sections that telescope for easy assembly to the stub shaft spindles. Three sections are used for cross collector, and for primary and secondary tank drive assemblies. When expanded and slip-fitted over the stub shaft spindle bearings, shaft sections are locked together with cast Nylon-6 interlocking key assembly and cast Nylon-6 shaft collars. The stub shaft spindles, bearings, drive shafts and rail components are all designed for use in conjunction with cast nylon drive and idler sprockets, reinforced nylon drive chain, molded reinforced polyester collector chain, pultruded fiberglass flights, and cast nylon wearshoes. Among the outstanding features of all these system components are their lightweight, strength and durability. Component for component, the plastic parts averaged at least 75% lighter than the iron or steel parts they are designed to replace. This reduced weight not only saves operating energy, but allows installation and regular periodic tank maintenance to be performed more quickly with less labor. For example, a standard 23-tooth, 565 mm pitch diameter cast nylon drive sprocket weighs approximately 16.8 kg, while a comparable cast iron or fabricated steel sprocket can weigh well over 50 kg. Thus one man can easily install or replace a plastic sprocket or bearing by himself without the aid of a crane or hoist. Chain installation and maintenance also requires a great deal less effort, since a 3 m section of reinforced polyester chain weighs just 6.3 kg compared with 26 kg for an equal length o steel or malleable iron chain. The various engineered plastic materials used to make the different sludge collector system components were selected on the basis of extensive laboratory research and evaluation of their performance in more severe applications. Among the principal criteria were resistance to water and chemicals commonly found in water and sewage treatment facilities, abrasion and corrosion resistance, tensile and impact strength, dimensional stability, and cost effectiveness. Cast nylon, long a cost-saving workhorse in heavy duty wear applications such as elevator buckets for sewage wastewater grit removal, was found to be best suited on all counts for sprockets, shaft spindles and bearings, wear shoes and wear strips. This material, the polyamide Nylon-6, is noted for its superior strength, rigidity, toughness, low creep, and abrasion and chemical resistance. It also is the most dimensionally stable of all the castable nylons under high moisture conditions. Immersion in water not only enhances its self-lubricity, but also improves its physical impact strength. The ability of Nylon-6 to be cast in large precision structural shapes permits the new stub shaft spindles to handle the full load of collector chain and flights moving at speeds up to 2.1 m/min well above normal operation speed of 0.4 m/min. The result is elimination of the need for heavy steel idler sprocket shafts. Plastic spindles also allow the use of lightweight, high torque tubular shaft sections for the head shaft sprocket drive assembly. Other objects and advantages of the present invention will be apparent and suggest themselves to those skilled in the art, from a reading of the following specification taken in conjunction with the accompanying drawings. Fig. 1 is an isometric view of an embodiment of the water clarifier and sewage treatment device; Fig. 2 is a view, taken along lines 2-2 of Fig. 1; Fig. 3 is a view, taken along lines 3-3 of Fig. 1; Fig. 4 is a view, taken along lines 4-4 of Fig. 1; Fig. 4A is a cross sectional view taken along lines 4-4 of Fig. 4; Fig. 5 is a view, taken along lines 5-5 of Fig. 3; Fig. 6 is a view, taken along lines 6-6 of Fig. 2; and Fig. 7 is a view, taken along lines 7-7 of Fig. 2. Referring to Fig. 1, a water-sewage treatment system 10 includes a rectangular tank 12 including side walls 14 (only one of which is illustrated), end walls 16 and a bottom floor 18. During operation, the tank 12 is filled with sewage or waste material to be treated or purified (not illustrated). The operating mechanism comprises a motor drive unit with shear pin drive sprocket assembly 20 and a drive chain take up unit 22. The unit 20 drives a sprocket 24 through a drive chain 26. The sprocket 24 drives a second sprocket 28 through means to be illustrated in subsequent figures of the drawing. The sprocket 28 drives sprocket 30 through a shaft assembly 32. The drive sprockets 24 and 30 are secured to drive shaft 32, which rotates on stub posts 33 and 37, which in turn are connected to side walls 14. The idler sprockets 34 are free turning and are connected to stub posts 35 which are also secured to the side walls 14. These stub posts are not connected to any shafts, with one such stub being illustrated in Fig. 4. When the sprockets 20 and 30 are driven, they drive the chains 36 and 38. Flight members 40 are secured to the chains 36 and 38. The flight members ride on bottom wear plates or tracks 42 and 44 (Fig. 3) and on top tracks, with wear plates 46 and 48. The flight members 40 scrape the top of the waste material in the tank 12 and pass it to the next stage in the overall treatment system, in a conventional manner. The tracks 42 and 44 include wear plates 45 and 47. The flight members 40 include wear shoes 51 and 53. Referring to Figs. 1, 4 and 6, details relating to the plastic stub posts, such as stub posts 33, and drive shafts 32 are illustrated. In the embodiment illustrated, the shaft 32 comprises, three telescoping tubular members comprising two end members 50 and 52 and intermediate tubular member 54. The intermediate tubular member 54 is disposed to fit into the end tubular members 50 and 52. The tubular members 50 and 52 extend through sprockets 24, 28 and 30, respectively, and connected to move with the sprockets, as will be described. A tube interlock key assembly 56 is provided for tubular members 50 and 54. In like manner, a tube interlock key assembly 58 is provided for the tubular members 52 and 54. This key assembly is illustrated in Fig. 7 wherein locking bar 59 extends through openings in tubular members 52 and 54 and held in place by any suitable fastening means. A shaft collar 60 which may be tightened provides a firm contact around the tubular member 54. In like manner, a shaft collar 62 is tightened around tubular member 54 to provide good contact therebetween. The shaft collars 60 and 62 prevent lateral movements of the intermediate member 54 with respect to the end members 50 and 52. The arrangements of the tube interlock assembly and shaft collars prevent relative movements between the members 50, 52 and 54 and permits the shaft 32 to operate as an integral piece. Providing the shaft 32 in multiple pieces facilitates the assembly and disassembly of various parts in the system, including the sprockets, chains and stub posts. The tubular drive shaft members are preferably made of epoxy fiberglass. The shaft collars 60 and 62 are of cast Nylon-6. As illustrated in Fig. 6, the shaft collar 62 is comprised of a pair of half rings 61 and 63 around the tubular member 54 held together by screws 65 and 67. Stub posts 33 and 37 are secured to side walls 14 of the tank 12 (Fig. 1). The stub posts 33 and 37 include shafts 64 and 66, respectively, and which are secured to the outer areas of the spindles by set screws. Nylon sleeves 81 and 83 are fixed to the shafts 64 and 66 by set screws. Bearing elements 78 and 72 are disposed to rotate freely around the sleeves 81 and 33 along with the sprockets 28 and 30. The stub post 37 for the drive sprocket 28 which may include a shear pin (not illustrated), includes a stub shaft spindle and bearing assembly for the drive sprocket. The stub shaft spindle is a solid one piece construction made from Cast Nylon 6 material or equivalent. Bearing is secured to spindle with plastic screws. Outside diameter of the stub shaft bearing slide-fit to inside diameter of plastic telescope drive shaft assembly. A shaft key 74 extends through member 52 and bearing 72 and connects the sprocket 30 to the member 52. Thus the member 52, sprocket 30 and bearing 72 are all connected to move together. In a similar fashion,shaft key 76 extends through shaft 50 and bearing 78 and connects the sprocket 23 to the member 50. A bull sprocket 80 has a shaft key 82 extending through the sleeve 78 to the member 50. The entire assembly including the bull sprocket 80 drive shaft assembly 32 all move together when the sprocket 24 is driven by the chain 26. The stub post 35 (Fig. 4) for the idler sprocket 3h comprises a stub shaft spindle made of a solid one piece construction from Nylon 6 material, predrilled for mounting to wall studs. Tubular idler stub shaft bearing 92 is constructed from cast Nylon-6 material or equivalent. A bearing 94 is secured to the spindle with a plastic key or pin 95. Stub shaft spindle will have cast Nylon-6 sprocket retainer plate mounted with one, 1"-8 x 4" long hex head bolt, flat washer, split lock washer 316 stainless steel. Referring to Figs. 3 and 5, the flight members 40 are secured to chains 36 and 38 with Fig. 5 illustrating the mechanical connections of one of the flight members to the chain 36. Attachment link 82 connected the flight member 40 to the chain 36 by nut and bolt arrangements 84,86. A wear shoe plate 88 is secured to the flight member 40 and disposed one of the wear strip track members. A plurality of runway support brackets 96 and 98 to receive runway tracks 39 and 41. Wear strips 80 and 90 are secured to the flight member 40 and disposed to ride on the tracks 39 and 41.

Claims: A water clarifier and sewage treatment device comprising a rectangular tank (12) including a floor, a pair of side walls (14) and a pair of end walls (16), spindles secured to the side walls (14), sprockets (28, 30, 34) received on said spindles, a pair of chains (36, 38) meshing with the sprockets (28, 30, 34), a pair of which sprockets (28, 30) is connected by a drive shaft (32) and driven by drive means (20, 24, 26) while the other ones are idler sprockets (34), and a plurality of flight members (40) secured to the chains (36, 38) for scraping the floor of the tank (12), characterized in that the drive shaft (32) consists of telescoping tubular members made of plastic material and in that the spindles are plastic stud posts (33, 37, 35). Device according to claim 1, characterized in that the drive shaft (32) comprises three telescoping tubular plastic members including two end tubular members (50, 52) and an intermediate tubular member (54) fitting into the end tubular members (50, 52) and connected therewith,which end tubular members (50, 52) extend through said pair of sprockets (30, 28) and are connected to move with said sprockets (30, 28). Device according to claim 2, characterized in that the three plastic members (50, 52, 54) are glass fibre-reinforced tube sections. Device according to claim 2 or 3, characterized in that each end tubular member (50, 52) is connected with the intermediate tube section (54) by a plastic tube interlock key assembly (56, 58) comprising a locking bar (59) extending through openings in the end tubular member (50, 52) and the intermediate tubular member (54) and held in place by plastic fastening means. Device according to one of the claims 2 to 4, characterized in that a plastic shaft collar (60, 62) is connected around the intermediate tubular member (54) in contact with each end tubular member (50, 52). Device according to one of the claims 2 to 5, characterized in that each stub post (33, 37) for the sprockets (28, 30) driven by the drive shaft (32) comprises a plastic main body secured to the side wall (14), a plastic shaft (64, 66) extending from the main body, a plastic sleeve (81, 83) secured to said plastic shaft (64, 66), a plastic bearing element (78, 72) surrounding said plastic sleeve (81, 83) and plastic means (76, 74) for connecting the respective end tubular member (50, 52) of the drive shaft (32) with said plastic bearing element (78, 72) and the sprocket (28, 30) to freely ride as a unit on the plastic sleeve (81, 83). Device according to claim 6, characterized in that the plastic sleeve (81, 83) is secured to said plastic shaft (64, 66) by means of plastic set screws. Device according to claim 6 or 7, characterized in that the means (76, 74) for connecting the respective end tubular member (50, 52) of the drive shaft (32) with said plastic bearing element (78, 72) comprise a pin element. Device according to one of the claims 2 to 8, characterized in that each stub post (35) for the idler sprockets (34) comprises a plastic main body secured to the side wall (14), a plastic shaft (92) extending from the main body, a plastic sleeve (94) surrounding the plastic shaft (92) and fixed thereto by a plastic pin (95), the idler sprocket (35) being supported to rotate freely on said plastic sleeve (92). Device according to one of the claims 1 to 9, characterized by a bull sprocket (30) driven by the chain (26) of the drive means (20) mounted around the end tubular member (50) of the drive shaft (32) and fixed thereon by a key (82) extending through the end tubular member (50) and the plastic bearing element (78). Device according to one of the claims 1 to 10, characterized in that the track members (42, 54) mounted in the floor of the tank (12) for engagement with the flight members (40), the flight members (40), the sprockets (28, 30, 34, 80) and the chains (26, 36, 38) are plastic elements.

Inventors: HANNUM, JOSEPH ROBERT
Applicants: THE BUDD COMPANY
Application year: 1986
Main classification: B01D21
IPC codes: B01D21, C02F1