GB2267657A - Scum board mounting - Google Patents

Abstract

A scum board 3 is mounted adjacent an overflow weir 5 in a sewage settling tank by a bracket, which may be of S, J or U-shape and supports the board 3 from the rim of the tank to facilitate maintenance. Board 3 may be vertically adjustable on the bracket. The bracket may be secured to the tank wall 1a by bolts which also secure the weir 5 (Figs 3, 4, 6). The part of the bracket which embraces wall 1a may be in two pieces to adjust to different wall widths (Figs. 7, 8). <IMAGE>

Description

IMPROVEMENTS RELATING TO WATER PURIFICATION The invention relates to the provision of scum boards and weirs in sewage treatment plants.

It is well known that once solids have been removed from waste water the water is further treated before it is deemed to be suitable for returning to the water supply system. During the process of purification filtered water is allowed to settle in tanks so that unfiltered particles can settle to the bottom of the tanks and the remaining water can be extracted for further treatment as appropriate.

During the settling process water is typically extracted via a weir from the upper layers of the tank. However, it is known that scum forms on the surface during the settling process and therefore it is common to provide a scum board adjacent a weir to prevent the scum from leaving the tank with the drawn off water. To this end, the scum board is typically positioned so that its uppermost surface protrudes above the surface of the water and its lowermost end Is submerged below the surface of the water. Further, the scum board is positioned innermost of the weir towards the centre of the tank therefore water leaving the tank must first pass underneath the scum board to do so. During this passage scum will remain towards the uppermost surface of the water and will be obstructed by the scum board.

It follows from the above that the number of scum boards will be related to the number of weirs associated with each tank. However, from time to time it is necessary to install or replace weirs and/or scum boards and in order to do so the settling tank must first be drained. This can involve the ferrying of water from the tank to a deposition site using a tanker. On average five to six trips may be needed to empty a single tank. Once the tank is empty of water scaffolding is constructed from the base of the tank up to the level of the weir and/or scum board and an operator can then install, maintain or replace the weir and/or scum board. As will be appreciated, this operation may involve the shutting down of a settling tank for at least a day and possible longer. However, despite this inconvenience this method of attending to settling tanks has been practised for over several decades.

It is therefore an object of the invention to provide an apparatus which facilitates the installation and maintenance of scum boards and/or weirs.

According to the invention there is therefore provided a scum board mounted on an angled bracket.

Preferably a scum board is movably mounted on the bracket so that its position with respect to the surface of water can be adjusted.

Preferably the bracket is of "U" section; alternatively it is of "J" section.

According to a further aspect of the Invention there is provided a weir mounted on an angled bracket.

Preferably the weir and the scum board are mounted on the same bracket.

Preferably the bracket is adapted to fit over a rim of a settling tank.

Preferably the bracket is of "S" section.

Preferably the bracket is adjustable to be adapted for varying sizes of rim.

Preferably the weir and scum board are made from plastics material.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 represents a side sectional view of the upper part of a settling tank; Figure 2 represents a side elevation view of a bracket in accordance with the invention; Figure 3 represents a side elevation view of a further embodiment of the invention; Figure 4 represents a side elevation view of a fixing means; Figure 5 represents a side elevation view of further embodiments of the bracket; Figure 6 represents a side elevation of a system assembly; Figure 7 represents a side sectional view of an adjustable bracket; and, Figure 8 represents a side elevation of an adjustable slide.

Referring to the drawings and firstly to Figure 1, there is illustrated the uppermost side of a settling tank 1 and an adjacent volume of water 2, which water is retained within tank 1.

The uppermost edge of tank 1 typically comprises a rim 1 a formed by the provision of a recess 1 b located within uppersurface 1 at a distance spaced from the innermost edge C of the tank.

Within tank 1 there is provided a scum board 3. Further, mounted on the innermost edge C of tank 1 is a "V notched weir 5. This "V" notched weir 5 is designed to safeguard against scum overflowing the weir as will be readily appreciated to those skilled in the art.

The mounting of scum board 3 within the tank 1 at a predetermined distance from the innermost edge C of the tank 1 is effected by means of an "S" sectioned bracket. The "S" sectioned bracket is adapted to overlie the rim la in use and to be attached to the rim la using conventional attachment means. It follows from the above arrangement that three limbs 6,7 and 10 of the "S" sectioned bracket are immersed in the settling tank water and the innermost of these limbs, with respect to the centre of the tank, is provided with attachment means 4 whereby the scum board 3 can be attached to the bracket. The attachments 4 are adapted to enable the scum board 3 to be movable vertically with respect to the surface of the water so as to allow correct positioning of the scum board 3 with respect to the surface of the water.

Although the "V" notched weir 5 is mounted on rim 1a of the tank, it is within the scope of the invention to mount the weir 5 on the bracket on arm 6.

Referring now to Figure 2, there is clearly illustrated an "S" section bracket in accordance with the invention which is provided with attachment means 4 to which a scum board 3 is attached and also attachment means 4a for the purpose of attaching the bracket to rim 1 a of a tank.

Figures 3-8 illustrate additional embodiments of the invention. Figure 3 shows a "U" shaped bracket and attached to the limbs 6 and 7 are the weir 5 and scum board 3 respectively. In this embodiment, both the weir 5 and scum boards are attached to the bracket in one operation, an example of the fixing being achieved by the arrangement as shown in Figure 4.

Seals 20 are situated between the weir 5 and the inner rim Ic. A threaded Hilti bolt 21 passes from within the rim ic, through the weir 5, washer 23 and limb 6 of the bracket to be locked in place with nut 22. The fixing of the scum board 3 on limb 7 is of a similar arrangement except that the threaded Hilti bolt 21 passes through a second lock nut 22a.

Figure 5 illustrates the "U" shaped bracket for mounting both a weir 5 and scum boards. Figure 5b shows a bracket for mounting a scum boards only. Figure 6 illustrates an example of a system assembly which can be used as an alternative to that described In Figure 4. In brief, the Hilti bolt passes from the inner rim 1c, through the weir plate 5, through a washer 24 and lock nut 25, the bracket limb 6, a further washer 23 and finally a lock nut 22.

Figures 7 and 8 show yet a further embodiment. In Figure 7 is shown a "U" shaped bracket to which is attached at limb 6 an adjustable slide fixing generally indicated 15. Figure 8 illustrates in detail the construction of the adjustable slide fixing 15. There are two L-shaped pieces 16 and 17, one arm of each L-shape fitting into an adjustable locking mechanism such that the adjustable slide fixing 15 is of a generally inverted "U" shape. The advantage of the adjustable slide fixing is to accommodate varying sized tank rims 1a. The locking mechanism 18 can be of a known type, for example, a threaded screw engaging a threaded socket or a telescopic mechanism.

In the embodiment shown in Figure 7, limbs of the U-shaped bracket can be adapted for releasably mounting on limb 17 so that, in use, the bracket can serve to support a trough for harbouring equipment and may be moved about the inner rim 1 c of a tank as a workman repairs/maintains the tank. Further, the trough may be of a pre-determined size and shape so as to provide a pattern for measuring pre-determined distances as it is moved about the inner rim 1 c.

It follows from the above that when wishing to install, maintain or replace either a weir 5 or a scum board 3 a tank 1 a need only be drained to a level just below that of the bracket and then an operator working from outside the tank can simply unfasten attachment means 4 and so lift the bracket and accompanying structures out of the tank 1 a. This therefore overcomes any need to completely empty the tank 1 a or render the tank 1 a inoperable for a period of days.

The invention is therefore embodied within a modular unit which can be easily and quickly mounted on the rim of a settling tank.

Claims (9)

1. An apparatus for controlling the purity of water comprising a scum board mounted on an angled bracket.

2. An apparatus according to Claim 1 wherein the scum board is adjustably mounted on the bracket so that the position of the scum board with respect to the surface of water can be adjusted.

3. An apparatus according to Claim 1 wherein the bracket is of U-section.

4. An apparatus according to Claim 1 wherein the bracket is of J-section.

5. An apparatus according to Claim 1 wherein a weir is mounted on said bracket.

6. An apparatus according to Claim 1 wherein said bracket is adapted to fit over the rim of a settling tank.

7. An apparatus according to Claim 7 wherein the bracket is of S-section.

8. An apparatus according to Claims 6 and 7 wherein the bracket is adjustable so as to accommodate varying sizes of rim.

9. An apparatus according to any preceding Claim wherein the weir and scum board are made from plastics material.