JPH02187111A - Method for concentrating sludge and device therefor - Google Patents

Abstract

PURPOSE:To eliminate the need for maintenance work such as cleaning of filter cloth, etc., by storing water temporarily after being sucked by low pressure filtration, then scraping solids off a filter layer to separate them, and thereafter forcing the water thus stored through the filter layer to the outside under low pressure, thereby conducting back washing. CONSTITUTION:When a rotary drum 1 is rotated on the center axis 15 clockwise at a specified speed, at first the volume of a chamber 4-1 dipped in a liquid to be concentrated 11 containing solids in a reservoir 10 expands and sucks water by the action of a cam 9 and spring member 5, following which the solids sucked on a felt 3 are scraped off by a scraper 12 and discharged to the outside through a sludge pan 13, while water in each of the chambers 4-1-4-8 is gradually discharged from the position of the chamber 4-5 by the action of the cam 9 to be discharged to the outside through a water pan 14; thereby, back washing of filter cloth 2 and felt 3 is performed, and then a next concentration operation starts.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for concentrating a liquid containing solids, and in particular,
The present invention relates to a method for concentrating sludge such as sewage sludge and an apparatus used therefor.

(Prior art) Concentration methods such as gravity concentration, pressure flotation, and centrifugation are conventionally known as methods for concentrating a liquid containing solids by reducing its water content. Various devices are also known.

Further, a concentrating device is also known that vacuum-suctions a liquid containing solids through a filtration layer, scrapes and separates the solids accumulated on the filtration layer, and discharges the filtered liquid to the outside.

(Problems to be Solved by the Invention) However, among the above-mentioned methods, the gravity concentration method cannot achieve a significant increase in concentration, requires a long residence time of usually 12 hours or more, and requires a large installation area. There was a big problem. In addition, the pressure flotation method and the centrifugation method require high electric power costs (power costs), which increases processing costs, and the pressure flotation method in particular has the problem of difficult maintenance.

In order to solve these problems, Japanese Patent Application Laid-Open No. 62-262800
In the publication, an apparatus is disclosed in which a polymer flocculant is mixed with a liquid containing solids to be treated and water is removed as a polymer gel mass. However, in this device, the polymer flocculant is disposable and cannot be reused, so there is a problem in that the running cost is high and it is difficult to prepare a specific sieve.

Furthermore, in the above-mentioned concentration device that uses vacuum suction, it is necessary to periodically interrupt the operation to clean the filtration layer, and a vacuum suction mechanism must be provided, which makes the device large and expensive. However, there was a problem in that the processing cost also increased.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a sludge thickening method and a thickening device used therein, which can achieve low running costs with low equipment costs and electric power costs, and are easy to maintain.

(Means for Solving the Problems) The sludge concentration method of the present invention suctions a liquid containing solids to be concentrated at low pressure through a filtration layer, deposits the solids on the filtration layer, and removes water after filtration. This method is characterized in that after once storing the solid content on the filtration layer, the solid content is scraped off and separated, and then the stored water is extruded at low pressure through the filtration layer and discharged to the outside.

In addition, the sludge A-ray device of the present invention includes a storage tank for storing a liquid containing solids to be concentrated, a water-permeable rotating drum with a filtration layer on its surface, and a volume provided inside the rotating drum. a plurality of chambers capable of suctioning and discharging the liquid in the storage tank by changing the number of chambers; a solid content removal means for scraping off solid matter adhering to the vicinity of the surface of the filtration layer after suction into the room through the filtration layer; The apparatus is characterized by comprising a moisture removing means for pushing and discharging moisture in the room to the outside through the filtration layer after solid content has been removed.

(Function) In the above-mentioned configuration, by absorbing the liquid containing the solid content to be concentrated through the filtration layer at low pressure, the solid content and the other liquid can be separated and concentration becomes possible.
Backwashing is performed by storing liquid other than solids in the room and discharging it to the outside through a filtration layer after solids are removed, so maintenance such as filter cloth cleaning can be eliminated.

In addition, the above-mentioned concentrator can absorb and drain water by changing the volume of the room, so it can perform continuous concentration operations, and it can also process without chemical injection, so it is possible to use a polymer flocculant. It is possible to achieve lower running costs than in the case of

Furthermore, it is preferable to use a cam to vary the volume of each room because the operation can be controlled only by rotating the drum.

(Example) FIGS. 1(a) and 1(b) are diagrams showing the configuration of an example of the concentrating device of the present invention and a partially enlarged view thereof. In this embodiment, a filter cloth 2 is provided on a rotary drum 1 made of water-permeable punched metal, and a felt 3 is further provided thereon to constitute a filtration layer. Inside the rotating drum 1, there are eight chambers 4- extending in the longitudinal direction of the rotating drum 1, each having a variable volume and capable of sucking and discharging a liquid containing solids to be concentrated.
1 to 4-8 are provided. Each of the chambers 4-1 to 4-8 includes iron plates 6-1 to 6-8 extending in the longitudinal direction of the rotating drum l via a spring member 5, and elastic members 7-1, 7-8 that can be expanded and contracted.
2. A plurality of follower nodes 8 of cams having rollers at the tips are provided outside the chambers of each iron plate 6-1 to 6-8, and the follower nodes 8 follow the expansion and contraction pattern of each chamber 4-1 to 4-8. The cam device is configured such that the cam 9 is always in contact with the spring member 5. In addition, a storage tank 10 is provided,
A part of the rotating drum 1 having the above-described structure is installed so as to be immersed in the liquid 11 containing the solids to be concentrated in the reservoir [10]. Furthermore, a scraper 12 is provided on the upstream side of the rotating drum 1 to scrape off solid matter such as sewage sludge adsorbed on the surface of the felt 3. In addition, a sludge receptacle for taking out the solid content scraped by the scraper 12 is a plate 13.
In addition, a moisture tray 14 is provided on the downstream side for temporarily storing moisture discharged from each of the rooms 4-1 to 4-8 through the filtration layer.

In the above-mentioned concentrating device, by rotating the rotating drum 1 clockwise with respect to the central axis 15 at a predetermined speed in FIG. 1, the solid content to be concentrated in the storage tank IO is first contained by the action of the cam device. Room 4-1 immersed in liquid 11
The volume expands and absorbs water. Thereafter, the solid content adsorbed on the felt 3 is scraped off by the scraper 12 and the sludge receiver is discharged to the outside via the tray 13, and the moisture in each of the rooms 4-1 to 4-8 is removed from the room 4-1. Water is gradually drained from the position 5 and the water is discharged to the outside through the dish 14, and after backwashing the filter cloth 2 and the felt 3, it is used again for the next concentration operation. Therefore, in the device shown in Figure 1,
The sludge concentration method of the present invention can be suitably implemented.

The filter cloth 2 forming the surface filtration layer is made of Tetron or nylon and has an air permeability of 1 to 30 cc/cm'·se.
It is preferable to use a material having good acid resistance and alkali resistance, preferably about 4 to 10 CC/Cm2.SeC, and it is preferable to use a felt 3 that is porous and has a thickness of 1 mm or more. Preferred examples of filter cloth and felt are shown in Tables 1 and 2, respectively.

Table 1 Table 2 FIG. 2 is a diagram showing the configuration of another example of the concentrating device of the present invention. In FIG. 2, the same members as in the example shown in FIG. 1 are given the same reference numerals, and their explanations will be omitted. The difference between the example shown in Fig. 2 and the example shown in Fig. 1 is that each room 4-1 to 4-
8 is entirely made of a stretchable elastic member, and the cam device is made of, for example, grooved cams provided at both ends of the rotating drum 1, and the follower section 8 is made of an elastic member in each chamber 4-1.
- 4-8 are connected to the metal fittings 16-1 to 16-8 extending in the longitudinal direction of the rotating drum 1 provided at the bottom. With this configuration, each of the rooms 4-1 to 4-8 can be expanded and contracted by the action of the cam device, similarly to the example shown in FIG. Therefore, even with the apparatus shown in FIG. 2, the sludge concentration method of the present invention can be suitably carried out.

The suction pressure in this device is 0.1 to 0.3 kg/
cm2, and the suction pressure in the vacuum dehydrator is 0.8
~1.0 kg/cm''.

The present invention is not limited only to the embodiments described above, and numerous modifications and changes are possible. For example, the number of compartments in the room mentioned above is not limited to eight, and
It is clear that the shape and type of the cam is also not limited to the embodiments described above.

(Effects of the Invention) As is clear from the above explanation, according to the sludge concentration method of the present invention and the apparatus used therein, by absorbing the liquid containing solids to be concentrated through the filtration layer at low pressure,
It is possible to easily separate solids from other liquids at low pressure and concentrate them, and the liquid other than solids can be stored in a room and discharged outside through a filtration layer after the solids have been removed. Since cleaning is performed, maintenance such as cleaning the filter cloth can be eliminated. Therefore, equipment costs and power costs are low, low running costs can be achieved, and maintenance of filter cloths and the like can be simplified.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a diagram showing the configuration of an example of the sludge thickening device of the present invention, a partially enlarged view thereof, and FIG.
The figure is a diagram showing the configuration of another example of the sludge thickening device of the present invention. ■...Rotating drum 3...Felt 5...Spring member? -1,7-2...Elastic member 9...Cam 11...Liquid 2...Filter cloth 4-1 to 4-8...Room 6-1 to 6-8...Iron plate 8 ...Subordinate node 10...Storage tank 12...Scraper 13...Sludge receiver is plate 15...Central axis

Claims (1)

[Claims] 1. A liquid containing solids to be concentrated is sucked at low pressure through a filtration layer, the solids are deposited on the filtration layer, and the water after filtration is temporarily stored, and then A sludge thickening method characterized by scraping and separating the solid content of the sludge, and then extruding the accumulated water at low pressure through a filtration layer and discharging it to the outside. 2. A storage tank for storing a liquid containing solid content to be concentrated;
A water-permeable rotating drum with a filtration layer on its surface, multiple chambers inside the rotating drum that can suck and discharge liquid in the storage tank by varying the volume, and a filtration layer that allows the liquid to be pumped into the room through the filtration layer. a solid content removing means for scraping off solid content adhering to the vicinity of the surface of the filtration layer after water absorption; and a water removal means for pushing and discharging the moisture in the room through the filtration layer to the outside after removing the solid content. A concentrating device characterized by comprising: