JPS5927278B2 - Belt filter press equipment for dewatering in sewage treatment plants, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter press used in sewage treatment plants and the like, and more particularly to a belt screen press.

It is well known that organic and/or inorganic additives are added to sludge generated in sewage treatment plants to promote flocculation of the sludge, and then the sludge is sent to a belt screen press for dewatering. The sludge is first dewatered in a horizontally disposed unpressurized belt section and then sent to a pressurized belt section.

It is also known to carry out preliminary dewatering to assist the action of the belt screen; such dewatering is carried out in a clarifying tank where the flocculated sludge settles and the separated water is removed before being sent to the belt press. or in a screening drum.

The disadvantages of this type of belt filter press equipment are:
The problem lies in the inability to suitably and flexibly adapt the pre-dewatering to belt screen presses.

The present invention overcomes the above-mentioned drawbacks and provides a pre-dewatering means which facilitates adaptation of the required dewatering operation to the sludge in terms of its characteristics or the proportion of dry matter contained therein, and which has high dewatering efficiency. The purpose of this invention is to provide a belt screen press with

The invention has been devised for the dewatering of sludge in belt filter press plants, more particularly sewage treatment plants, which are arranged above the screen belt,
The above-mentioned problems have been solved by dewatering the sludge prior to the belt screen press and further having a pocket-shaped rotating filter chamber for receiving the sludge.

The dewatering means according to the invention can be constructed as a cell drum with cells each having a pocket-like filter chamber;
When a large throughput and a large dehydration effect are required, the dehydration means is preferably configured as a belt pocket filter.

The pockets of the rotary filters of both embodiments according to the invention are capable of very good pre-dewatering, and furthermore it is possible to control the dewatering rate by adjusting the speed of the pocket-shaped rotary filter.

For example, if it is desired to obtain a specific degree of dryness or amount of solids in the final sludge, within a limited maximum speed of the belt screen press, the dewatering means can be modified by varying the conveying speed of the pocket filter. The speed should be adapted to the speed of the belt screen press.

In all cases it is advantageous to arrange the pre-dewatering means above the horizontal part of the belt screen press.

The invention can also be applied to box filter presses (also referred to as frame filter presses), in which case the pre-dewatering means are placed upstream of the box filter press.

The invention can also be applied to drying beds in sewage treatment plants.

That is, before being sent to the drying bed, the sludge is mixed with a flocculant, flocculated and then sent to a pre-dewatering means where it is substantially dewatered before being sent to the drying bed.

This allows the surface area of the bed to be reduced to a fraction of that normally required.

Other advantages of the invention will become apparent from the accompanying drawings and the following description based on the examples.

In the figure, reference numeral 1 denotes a sludge metering pump which feeds sludge into a conical mixer 2 having an agitator 3 rotated by a hollow shaft 4 .

A flocculant is fed into the mixer 2 through the hollow shaft 4 through nozzles at the ends of its three arms for mixing into the sludge.

The sludge mixed with the flocculant rises within the mixer 2 and reaches the reaction chamber 6.

The reaction chamber 6 may be provided above the mixer 2 as in the illustrated embodiment, or may be provided at another location.

The sludge flocculated by the flocculant is fed through a pipe 51 with a horizontal section 52 to a compartment drum 53 for preliminary dewatering.

The pre-dewatered sludge is sent from the drum 53 to the outer filter belt 9.

The filter belt 9 first passes over the pulley 29, and
associated with means for imparting controllable vibrations to the belt 9.

At the end of the horizontal movement section, the filter belt 9 is guided downward and forms a wedge-shaped space with the second filter belt 10.

In this way, filter belts 9 and 10 entrain the sludge sent to filter belt 9 between them.

The filter belts 9 and 10 are supported from below by support rolls 33.

Water or other liquids are squeezed out of the sludge as it is pressed by pressure rolls 34 from above.

The belts 9 and 10 are made of a thin mesh, and
They are supported by back belts 11 and 12, respectively.

The back belts 11 and 12 are constructed in such a way that they can absorb maximum compressive forces.

Examples include steel wire woven into a steel crossbar.

Reference numeral 21 is a tension adjuster for the back belts 11 and 12;
22 is a tension adjuster for filter belts 9 and 10.

After passing through the pressure application station in a horizontal position, the filter belts 9 and 10 and the back belts 11 and 12 are guided onto a rotating drum.

The rotating drum is configured as a roll cage 13 and is rotated via a drive shaft 17 by a motor 18 .

The direction of rotation of roll cage 13 and shaft 17 is reversible so that roll cage 13 can rotate in the same or opposite direction as belts 9-12.

Of all belts, only belts 11 and 12 are connected to motor 1.
It is advantageous to rotate belts 9 and drum 20 and to move belts 9, 10 with the movement of belts 11 and 12.

The pressure applied to the belts 9-12 at the pressure application portions is adjusted by springs.

Preferably, the compression spring is gradually strengthened along the sludge compression path so that the dewatering pressure increases gradually.

Further, the speed of the roll cage 13 is different from the speed of the belts 9 to 12, so that the static pressure roll 14 is connected to the roll cage 1.
It is preferable to enter the gaps between the rolls of No. 3 and force the sludge and the belt to perform a wave-like motion to ensure a reliable action on the sludge.

The liquid squeezed from the sludge during the entire trip is collected by a collection-discharge plate 25 thrown below each belt and into the roll cage 13.

A feature of the invention is the provision of effective means for liquid collection and discharge, and more particularly for ensuring that once removed, the liquid does not return to the sludge.

Reference numeral 26 designates a nozzle for cleaning the filter belts 9, 10 before loading them with sludge again.

As can be seen, the filter belt 9.10 points upwardly away from the roll cage 13 in the last percent of its working area.

This allows the squeezed out liquid to flow downward in this portion.

The cell drum 53 is driven clockwise in FIG. 1 by a shaft 54.

Shaft 54 is surrounded by a hollow shaft 55 with cell walls 56.

Each cell between the cell walls 56 has a pocket 57 which is wedge-shaped in cross section and includes a screen with a mesh larger than the filter belts 9, 10, and whose sides are constructed with similar screens.

These screens are designated 58 in the figure.

The axial length of the screen drum is the filter belt 9
．． Corresponds to 100 width.

The screen drum is driven by a motor 65 at various speeds.

The entire screen drum is housed in a casing 49, and the right side portion in the figure is covered with a screen 60.

The flocculated sludge is transferred from the reaction chamber 6 to the pipe 51 and its horizontal section 52.
The sludge is sent to a discharge hole having a length approximately corresponding to the length of the cell drum 53 and falls into the pocket 57 located at the top, and most of the water in the sludge passes through the screen 58.
It reaches the space between the shaft 54 and the hollow shaft 550 and is flowed in the axial direction.

Each pocket is separated from each other by a compartment 56,
Water released from one pocket is prevented from flowing into other adjacent pockets.

The dewatering operation continues until the sludge contained in each pocket is delivered to the filter belt 9 near the bottom of the screen drum, whereupon it is subsequently dewatered by conventional means using a belt screen press.

In the embodiment shown in FIG. 2, the dewatering device is constructed as a screen pocket filter, which is suitable when large production volumes or high degrees of dryness are required.

In the belt pocket filter, the rotating conveyor belt 6
1 has a screen pocket 62 and a partition wall 63 made of a screen.

Both ends of the belt 610 are wound around a cell wheel 64.

The motor is designated at 65.

As in the embodiment shown in FIG. 1, the sludge flocculated by the flocculant passes from the reaction chamber 6 through the pipe 51 and its horizontal section 52 to the discharge hole 66, from where it is sent to each pocket for dewatering. It will be done.

The upper part of the belt 61 moves from left to right in FIG.

The discharged water from each pocket is collected by a collection plate 67 and directed laterally.

The dewatered sludge is transferred to the filter belt 9 at the lowest point of the right drive wheel 64.

The left wheel need not be of compartment construction, but could be configured so that the bars of the cage engage between each pocket when the belt is reversed.

Reference numeral 68 designates an injection device located in the left wheel area for cleaning the pocket screen.

The belt pocket filter shown in FIG. 2 is surrounded by a casing 69, similar to the cell drum shown in FIG.

The screen of the pocket filter is the filter belt 9,
It has a grain coarser than 10.

The conveyance speed of the belt pocket filter can be arbitrarily adjusted or set according to normal conditions.

For example, a sludge containing 4% dry matter at 10 m°/hour
Assuming that it is processed at a rate of
, Om'.

Approximately 15% dry matter with 7.35771' of discharged water can be treated with pocket dewatering.

The rate of sludge at the transfer point of the pocket dewatering system to the belt screen dewatering system is therefore only 2.65 m'/h at a drying rate of 15%.

Therefore, the speed range is lower than that of the pocket dewatering system, so that the pressure application time on the pre-dewatered sludge and the dewatering time itself can be determined accordingly depending on the final dry mass required. Inside, a belt screen dewatering system can be operated.

Tests have shown that 30% to 40% dry matter is obtained in the final sludge.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional view of a belt screen type dewatering device configured as a drum filter, and FIG. 2 is a longitudinal sectional view showing another embodiment of the drum filter. . 1... Sludge metering pump, 2... Mixer for mixing with flocculant, 51, 52... Piping, 53
... Cell drum, 9, 10 ... Belt filter, 33, 34 ... Pressure roll, 11,
12... Back belt, 13... Roll cage (rotating drum), 57... Filter pocket.

Claims (1)

[Claims] 1. Dewatering in a sewage treatment plant, etc., characterized in that a dewatering means having a pocket-shaped rotating filter chamber 57° 62 for receiving and taking sludge is provided in the front stroke part of the screen belt 9,100. belt filter press equipment. 2. The device according to claim 1, wherein the dewatering means is a cell drum 53 composed of cells (compartments) having pocket-shaped filter chambers 57. 3. The apparatus according to claim 1, wherein the dewatering means is an endless belt 61 composed of cells (compartments) having pocket-shaped filter chambers 62. 4. Device according to claim 1, 2 or 3, characterized in that the dewatering means are located above the horizontal intake of the screen belt 9. 5. Claims 1 and 2 are characterized in that the dewatering means 53 and 61 can be driven at different speeds.
The device according to any one of paragraphs 3 and 4.