SCUM REMOVING DEVICE

Abstract: A scum removing device operating in association with a member movable in a treating pool, comprising a trough, a barrage member and a transmitting mechanism, wherein the trough is of a fixed type and the movable member floats or sinks the barrage member through the transmitting mechanism. The scum removing device is constructed such that a sinking barrage member induces scum into the trough and a floating barrage member stops to induce scum into the trough. The barrage member is supported by a rotary shaft and the shape of the barrage member itself is specified to be oval, so that the induction of scum is made smoother and stabler and the construction of the transmitting mechanism is simplified. Sealing between the barrage member and the trough can be easily and reliably attained by a fixed sealing means on the trough side and a side plate on the barrage member side.

Description: FIELD OF THE INVENTION The present invention generally relates to a scum removal apparatus for efficiently removing scum floating in a sewage treatment pool and, more particularly, to a simplified scum removal apparatus of a type effective to efficiently remove scum by the utilization of a driving power generated by a movable member installed in the sewage treatment pool and without relying on a dedicated driving power. Such a scum removal apparatus according to the preamble of claim 1 is for example known from JP-U3 115 093. BACKGROUND ART Figs. 6 and 7 of the accompanying drawings illustrate such a scum removal apparatus known from JP-U3 115 093 and suggested by the inventor of the present invention. A generally rectangular sewage settling pool is provided with a plurality of, for example, four, sprocket shafts 200 extending in a widthwise direction of the sewage settling pool, a pair of sprocket wheels 201 mounted on each of the sprocket shafts 200 and generally endless, left-hand and right-hand chains trained around the sprocket wheels 201 on the sprocket shafts 200. In the suggested scum removal apparatus, some or all of the flights 203 secured to the chains 202 are driven together with the chains 202 to draw and remove the scum floating on the water surface in the sewage settling pool. The scum removal apparatus includes a trough 205, a guide support sheet 206, weir member 208 and a transmission mechanism 209. The trough 205 is in the form of an elongated member of a generally U-shaped cross-section opening upwardly and frontwardly and is fixedly disposed in the sewage settling pool so as to extend in the widthwise direction of the sewage settling pool. The guide support sheet 206 is a band of rubber material of a length corresponding to that of the trough 205 and secured at one front side portion to an upper edge of a front wall of the trough 205 with the opposite rear side portion thereof protruding frontwardly from the front wall of the trough 205 so as to undergo undulation by the effect of its elastic deformation. The weir member 208 is in the form of a generally elongated member having a front portion of a generally right triangular hollow cross-section and a rear portion of a generally rectangular cross-section and has a base portion secured to the front side portion of the guide support sheet 206 so as to protrude outwardly therefrom so that, while supported by the guide support sheet 206, the weir member 208 can undergo a wavy motion above and below the fluid surface level 207 of sewage in the sewage settling pool. It is the transmission mechanism 209 that drives the weir member 208 to move up and down with respect to the fluid surface level 207 in the sewage settling pool. This transmission mechanism 209 includes a rotary support shaft 210, a drive arm 211, and an operating arm 212. The rotary support shaft 210 is supported so as to extend widthwise of the sewage settling pool whereas the drive arm 211 is supported so as to extend from one end portion of the rotary support shaft 210 in a frontward direction substantially perpendicular to the rotary support shaft 210. The operating arm 212 is supported so as to extend in a direction counter to the direction of extension of the drive arm 211 and towards the trough 205 and is employed for each of the left-hand and right-hand sides of the sewage settling pool for the purpose of a stabilized operation. The drive arm 211 has a front end portion provided with a follow-up member 213. The follow-up member 213 has a cam face defined at a bottom thereof, which cam face is constituted by two hill areas 213a and 213c and a dale area 213b positioned between these hill areas 213a and 213c. It is a roller (a drive unit) 214, protruding outwardly from one end of each flight (mud dragging member) 203, that drives the follow-up member 213 to actuate the drive arm 211 and the operating arm 212 to move the weir member 208 up and down with respect to the fluid surface level 207 of sewage in the sewage settling pool. This roller 214 is supported by a bracket secured to one end of the follow-up member 213 associated with each flight 203. Reference numeral 220 shown in Figs. 25 and 26 represents a side seal (a sealing means) disposed between each side end of the weir member 208 and the adjacent side end of the trough 205 for avoiding a leakage of scum and water. This side seal is made of rubber material and is corrugated into a bellows between each side end of the weir member 203 and the adjacent side end of the trough 205 so that it can selectively expand and contract due to its elasticity in response to an undulating motion of both of the weir member 208 and the guide support sheet 206. The suggested scum apparatus shown in Figs. 25 and 26 operates in the following manner. When a drive motor (not shown) installed on a ground outside the sewage settling pool is powered, the chains 202 are driven so that the flights 203 coupled with the chains 202 are driven so as to slowly circulate along a generally rectangular path as indicated by the arrows in Figs. 25 and 26. The flights 203 being circulated successively scrape the sediment at the bottom of the sewage settling pool to guide it to a pit 221 in the bottom of the sewage settling pool so that the sediment so guided into the pit 221 can be subsequently discharged by a suitable pump (not shown) to the outside of the sewage settling pool. Some of the flights 203 moving along a path adjacent the fluid surface level 207 during the circulatory motion thereof successively push the follow-up members 213 by means of the rollers 214. The rollers 214 are then brought into engagement with the follow-up members 213 in a first stage, first contacting the hill area 213a, then contacting the dale area 213b and finally contacting the hill area 213c, to thereby move the follow-up members 213 up and down. When each roller 214 is brought into engagement with the hill area 213a of the respective follow-up member 213, both of the follow-up member 213 and the associated drive arm 211 are lifted a considerable distance and, at the same time, the associated operating arm 212 is lowered, causing the weir member 208 to be pushed beneath the fluid surface level 207 by means of a rod 224. At this time, the scum S floating on the top surface of the sewage, regardless of the size thereof, is guided into the trough 205 by the flow of water and is then discharged out from the trough 205. When each roller 214 is however brought into engagement with the dale area 213a of the respective follow-up member 213 in a second stage, both of the follow-up member 213 and the drive arm 211 are temporarily lowered while the associated operating arm 212 is lifted. Consequently, the weir member 208 having been lowered beneath the fluid surface level 207 is elevated a slight distance and, therefore, the amount of water component flowing over the weir member 208 into the trough 25 becomes small. Although the amount of the water component flowing over the weir member 208 is small, the velocity of flow of the water component becomes so high as to result in an increase of the force with which the scum S is drawn towards the trough 205. Therefore, scum lumps, small and large in size and/or floating near and a substantial distance away from the trough 205, can be smoothly drawn close towards the trough 205. On the other hand, when each roller 214 is subsequently brought into engagement with the hill area 213c of the respective follow-up member 213 in a third stage, both of the follow-up member 213 and the drive arm 211 are again elevated and the associated operating arm 212 is lowered. Once this occurs, the weir member 208 is lowered to guide a substantial amount of the scum S, drawn close towards the trough 205 in the manner described above, into the trough 205. Thus, since the follow-up member 213 moves so as to perform the three stages, the draw of the scum S to throw it into the trough 205 can be performed with considerably high efficiency. However, the above described scum removal apparatus has been found having the following problems. Since the weir member 208 is supported by the guide support sheets 206 made of rubber material, the weir member 208 is held in an instable condition and, accordingly, the use of the plural operating arms 212 and also the use of the rotary support shaft 210 having a length corresponding to the width of the sewage settling pool are required, making the scum removal apparatus as a whole complicated in structure and costly to assamble. Also, since the operating performance of the weir member 208 is not consistent during the operation thereof, the amount of scum drawn thereby is not always constant. Since the weir member 208 is in the form of a generally elongated member having a front portion of a generally right triangular hollow cross-section and a rear portion of a generally rectangular cross-section and is of one-piece construction, the molding thereof is very complicated and requires a high cost. Also, there is a problem in that, since the top of the front portion of the weir member 208 protrudes upwardly, some of the scum lumps tending to ride over the front portion of the weir member 208 are often entangled, thereby failing to ride over the front portion of the weir member 208. Also, since the rear portion of the weir member 208 is substantially in the form of a rectangular-sectioned plate, some of the scum lumps having ridden over the front portion of the weir member 208 tend to gather around the rear portion of the weir member 208 to such an extent that the weir member 208 may fail to operate properly and its outer appearance tends to be spoiled. Also, since the side seal 220 is in the form of bellows, not only does it require a high cost, but the attachment thereof is also considerably complicated. Accordingly, the present invention has been devised to substantially eliminate the problems discussed above. An object of the present invention is to make it possible to manufacture, at a reduced cost, the scum removal apparatus as a whole which is simple in structure and wherein the weir member can operate stably even though the operating arm employed is a single short rotary support shaft and also to stabilize the operating performance of the weir member so that the amount of scum drawn can be maintained constant. The molding of the weir member can be achieved simply and at a reduced cost, and can be so designed as to allow the scum to easily ride over the weir member. Design has been made to avoid the scum from gathering around the weir member. Also, design has been made to avoid the scum from being accumulated on the way to thereby render the weir member to be comfortable to took at. Design has also been made to render the seal means to be simple in structure and inexpensive and to permit the attachment thereof to be performed very simply. DISCLOSURE OF THE INVENTION The above mentioned problems are salved by a scum removal apparatus according to claims 1 or 2. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a fragmentary perspective view of a scum removal apparatus according to a preferred embodiment of the present invention; Fig. 2 is an exploded view of a sealing means used in the scum removal apparatus shown in Fig. 1; Fig. 3 is a schematic side view of a portion of the scum removal apparatus shown in Fig. 1, showing a manner of removal of the scum; Fig. 4 is an explanatory diagram showing an operating mode of the scum removal apparatus shown in Fig. 1; Fig. 5 is a fragmentary sectional view showing an another preferred embodiment of the present invention in which a supplemental element is fitted to a weir member; Fig. 6 is a fragmentary perspective view showing one example of the conventional scum removal apparatus; and Fig. 7 is a schematic perspective view of the conventional scum removal apparatus shown in Fig. 25. BEST MODE FOR CARRYING OUT THE INVENTION To facilitate a better understanding of the present invention, the present invention will be described with reference to the accompanying drawings. Figs. 1 to 5 illustrate one embodiment of the present invention. In this embodiment, there is shown a sewage settling pool (a treatment pool) rectangular in shape as viewed from above, and this rectangular sewage settling pool is provided, as shown in Fig. 3, with a plurality of, for example, four, sprocket shafts 300 supported so as to extend in a widthwise direction of the sewage settling pool, a pair of sprocket wheels 301 rigidly mounted on each of the sprocket shafts 300 and generally endless left-hand and right-hand chains 302 trained around the respective sprocket wheels 301 on each sprocket shaft 300. A plurality of flights 303 are mounted on the endless chains 302 in a substantially equally spaced relationship around the chains 302 so that the flights 303 can undergo a circulatory motion along a generally rectangular path together with the chains 302. A bracket 304 is secured to one of opposite ends of all or some of the flights 303 (that end over the flight 303 shown in Fig. 1 so far as the illustrated embodiment is concerned) and carries a roller support shaft so as to extend outwardly therefrom with a roller 305 mounted on a free end of such roller support shaft. This roller 305 on all or some of the flights 303 can undergo a circulatory motion along a generally rectangular path including an upper horizontal path component adjacent a fluid surface level 306 of the sewage in the sewage settling pool extending in a direction shown by the arrow in Fig. 1, a diagonally downwardly lowering path component, a lower horizontal path component extending along the bottom of the sewage settling pool and an elevating path component, before it is brought to a position immediately beneath the fluid surface level 306. A scum removal apparatus is provided with a trough 308. This trough 308 is of a generally U-shaped cross-section and includes a rear wall 308a, a major portion of which is sunken beneath the fluid surface level 306, but having an upper portion protruding above the fluid surface level 306, a bottom wall 308b positioned beneath the fluid surface level 306, and a front wall 308c of a height lower than that of the rear wall 308a having an upper portion positioned beneath, but adjacent to the fluid surface level 306. A front flange 308d is integrally formed with the front wall 308c so as to protrude frontwardly from the upper portion thereof in a direction opposite to the rear wall 308a. The trough 308 is of the generally U-shaped cross-section opening upwardly and, also, diagonally frontwardly and is of a length slightly smaller than the width of the sewage settling pool. This trough 308 is fixedly installed in the sewage settling pool with its lengthwise direction oriented widthwise of the sewage settling pool. Opposite ends of the trough 308 are provided with respective end plates 308e. A connecting trough 311 inserted through and fixed in a wall forming the sewage settling pool with its opposite ends protruding outwardly in opposite directions from the wall of the sewage settling pool is bolted to each end plate 308e by means of a flange 311a integral with the connecting trough 311. The connecting trough 311 is of a generally square cross-section and is used to communicate the troughs 311 in the neighboring sewage settling pools. It is to be noted that the trough 308 is so slightly inclined with one end thereof held at a level higher than the opposite end thereof that fluid can flow from the higher end of the trough 308 towards the lower end thereof by the effect of a gravitational force. This can in practice be accomplished by setting the bottom wall 308b of the trough 308 inclined. Therefore, scum and water component can be gathered having flowed in one direction and then guided to the next succeeding treatment system. An elongated bottom seal member 312 of a generally U-shaped cross-section made of rubber material is rigidly secured to the front flange 308d by means of an elongated retainer plate 313. This bottom seal member 312 has rear and front wall portions, the rear portion having a height greater than that of the front wall portion. Bearings 314 are fixedly connected to opposite respective ends of the front flange 308d, and a tubular rotary shaft 315 is supported by these bearings 314 so as to extend substantially parallel to the front flange 308d. A weir member (a float) 317 is supported by the rotary shaft 315 so as to undergo a rocking motion about the longitudinal axis of the rotary shaft 315. The weir member 317 is of a generally flat tubular configuration having a generally elliptical cross-section and of a length sufficient to extend widthwise of the sewage settling pool. The rotary shaft 315 has front and rear rounded sides with the rotary shaft 315 extending through the rear rounded side thereof. Opposite ends of the weir member 317 have respective end plates 318 rigidly secured thereto with opposite ends of the rotary shaft 315 extending outwardly therethrough to left-hand and right-hand sides. Each of the end plates 318 is sandwiched between sealing means 320 provided on the trough 308. The sealing means 320 comprises a fixed plate 321 fixed to each end of the trough 308 so as to extend upright and having a gap between left-hand and right-hand portions thereof, flat rubber seal plates 322 disposed on respective sides of the fixed plate 321, main seals 323 each having one end formed into a tapered lip and seal retainers 324, all of which are fastened together by means of bolts and nuts. The end plates 318 can move from and aft in gaps formed among these elements to avoid any possible leakage of water component from the front. It is to be noted that the front rounded side of the weir member 317 has a plurality of recesses 317a defined therein so that relatively large scum lumps can be drawn by these recesses 317a. Reference numeral 325 represents a bracket secured to a side wall 310 of the sewage settling pool. This bracket 325 has a single operating arm 327 having a generally intermediate portion rotatably connected thereto by means of a rotary support shaft 326 while extending transverse to the rotary support shaft 326. The operating arm 327 has a front free end provided with a follow-up member 328 and also has a rear free end operatively coupled with a rod 329. It is to be noted that, where the weir member 317 has a relatively small width, an supplemental element 331 may be connected to one or each end of the weir member 317 by means of a bolt 330 threaded thereto through the supplemental element 331 as shown in Fig. 5. In such case, the supplemental element 331 may have its tip provided with sharp projections 333 effective to break the scum S into pieces. The operation of the scum removal apparatus of the above described construction is shown in Figs. 3 and 4. Assuming that temporary contact points in the follow-up member 328 are expressed by a, b, c, d and e, from the front to the rear, respectively, by the time the roller 305 is brought into contact with the contact point a of the follow-up member 328, the weir member 317 is positioned still above the fluid surface level 306. However, during a period subsequent to the contact of the roller 305 with the contact point a and prior to the contact of the roller 305 with the contact point b, the follow-up member 328 is lifted while the weir member 317 is lowered beneath the fluid surface level 306 by means of the operating arm 327 and the rod 329. When the roller 305 relatively rolls over to the contact point b, the weir member 317 is held substantially horizontally to draw a relatively large amount of the scum S. When the roller 305 rolls from the contact point b over to the next contact point c in the follow-up member 328, the follow-up member 328 is conversely lowered a slight distance with the weir member 317 consequently lifted but still beneath the fluid surface level 306 and, in this condition, the amount of water component drawn thereby is somewhat restricted. However, some of the scum S far away from the trough 308 are effectively drawn as described above. When the roller 305 rolls over to the contact point d, the weir member 317 is lowered again to draw a relatively large amount of the scum S. When the roller 305 is subsequently brought into contact with the contact point e in the follow-up member 328, the follow-up member 328 is lowered while the weir member 317 is floated above the fluid surface level 306 with the consequence that the drawing of the scum S is temporarily interrupted. During this condition, the seal is assuredly and simply achieved by the bottom seal 312, the sealing means 320, the end plates 318 and others. It is to be noted that, as shown in Fig. 1, a shaft X may be mounted by a plurality of bearing (not shown) so as to extend parallel to the lengthwise direction of the sewage settling pool for rotation about the longitudinal axis thereof and that an auxiliary arm 328b may be connected to the shaft X so as to extend perpendicular thereto while a follow-up member 328a having a free end provided with a plurality of corrugations is fitted to a free end of the arm 328b. In such case, when the roller 305 approaches, the follow-up member 328a is selectively shifted upwardly and downwardly about the shaft X to thereby cause the weir member 317 to be elevated and lowered by a transmission mechanism with respect to the fluid surface level 306. INDUSTRIAL APPLICABILITY As hereinabove described, the scum removal apparatus according to the present invention is installed in the initial or final sewage settling pool and is useful as a handy apparatus for removing and collecting scum floating on the fluid surface level. The present invention is so designed as to be applicable to all apparatuses operable to remove and collect the scum by the utilization of the driving power delivered from the existing movable member in the sewage treatment pool and can be manufactured very compact in size and at a reduced cost while satisfying the demands of each installability at site.

Claims: A scum removal apparatus which comprises: a generally U-sectioned trough (308, 205) fixedly installable in a sewage treatment pool, such as a sewage settling pool, with a lower portion thereof to be submerged beneath a fluid surface level (306, 207) in the sewage treatment pool and with an upper portion thereof to emerge upwardly above the fluid surface level, said trough (308, 205) having an opening defined at one side thereof, said trough being operable to discharge scum and a water component, which have been introduced thereinto through the opening; a weir member (317, 208) provided adjacent the opening of the trough (308, 205) so as to undergo a rocking motion with an upper side portion thereof moving up and down with respect to the fluid surface level (306, 207) for guiding and interrupting the flow of the scum and the water component into the trough; and a transmission mechanism (209) for transmitting a force to the weir member (317, 208) to cause the weir member to undergo the rocking motion and including a follow-up member (328, 213) adapted to be actuated in contact with a drive unit provided in each of flights (303, 203) within the treatment pool, wherein the trough is provided with a rotary shaft to permit the weir member to move up and down; characterized in that one side of the trough (308) adjacent the opening is provided with the [a] rotary shaft which extends parallel to the fluid surface level (306) and that said weir member (317) is a generally elongated member having an elliptical cross-section. A scum removal apparatus according to claim 1 characterized in that said weir member (317) has its opposite ends provided with respective end plates (318) while said trough is provided with sealing means (320) sandwiching each of the end plates (318) for sealing between the trough (308) and the associated end plates.

Inventors: FUJIWARA MICHIHIRO, FUJIWARA, MICHIHIRO
Applicants: FUJIWARA MICHIHIRO, FUJIWARA TOSHIMI, FUJIWARA, MICHIHIRO, FUJIWARA, TOSHIMI
Application year: 1992
Main classification: C02F1
IPC codes: B01D21, C02F1