SU1388083A1 - Method and apparatus for dehydrating sediments - Google Patents

Description

(21) 4100615 / 29-26

(22) 08/07/86

(46) 04/15/88. Бкш..№ 14

(72) S.V. Yakovlev, I.S.Turovsky,

A.S. Kerin, Yu.V.Gutin and Yu.I.Turovsky

(53) 66.067.3 (088.8)

(56) U.S. Patent No. 3,774,760, cl. 100/118, 1971.

(54) OCAJIKOB DECOMPOSITION METHOD AND DEVICE FOR ITS IMPLEMENTATION

(57) The invention relates to methods and devices for dewatering sludge obtained during the purification process of municipal, industrial wastewater and natural water, and improves the performance of the device, simplifies its design and reduces the moisture content of the sludge. A sludge dewatering device that implements the method comprises infinite elastic porous filter belt 1,

passing along guiding elements 2 through squeezing elements 3 and 4, as well as sludge receiving trays 5, pressing elements 6, knives 7 for removing sludge, tank for collecting filtrate 8 and dehydrated sludge 9, squeezing elements 4 located in the lower part of the filtering ribbons 1, made perforated and have a diameter greater than the squeezing elements 3 in the upper part, in the ratio (1.5-2.0): 1. Sludge dewatering is carried out simultaneously in the upper part of the outer and lower parts of the inner side of the filter belt, the thickness of which is 4 / 5-9 / 10 of the layer of sediment on it, with a specific filtration resistance of the original sediment (1-1000) l x 10 cm / g and a duration of dehydration of 6-300 s. 2 sec. and 1 z. p. f-ly, 3 ill., 4 tab.

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The invention relates to the dewatering of sediments and can be used in various areas of sewage, for example for dewatering (or thickening) the sediments obtained during the treatment of municipal and industrial waste and natural waters.

The aim of the invention is to increase the productivity and simplify the design of the device, as well as reduce the moisture content of the dried sludge,

FIG. 1 shows a diagram of a device for dewatering sludge; in “FIG. 2 is a graph that selects the duration of the dewatering process depending on the resistivity of the original sludge filtrations; in fig. 3 is a schematic diagram of an apparatus for controlling the duration of a dewatering process as a function of resistivity. The sludge dewatering device contains an endless elastic porous filter belt 1 passing along the guiding elements (rollers) 2 through squeezing elements (rollers) 3 and 4, as well as sediment receiving trays 5, pressing elements (rollers) 6, knives 7 for removal of sludge, tank 8 and 9 for collecting filtrate and dehydrated sludge, respectively. .

The sludge dewatering device operates as follows.

The precipitate, without preliminary preparation or treated with chemical reagents, is fed through the receiving trays 5 to the elastic porous filter belt 1 at the same time in its upper and lower parts and, moving with it towards the squeezing elements (rollers) 3 and 4, is subjected to dewatering due to the suction of the filtrate by the capillary forces of the porous ribbon, which are formed during its preliminary compression and decompression due to the passage through the direction of the deformation elements (rollers) 2 and pressing elements (rollers) 6, installed Before receiving trays. The porous tape was filtered and dehydrated by the filtrate, the squeeze rollers 3 and 4 were run. To more efficiently press the tape and remove the filtrate, the bottom squeeze roller 4 was made perforated and its diameter was larger than the upper squeeze roller 3. Preventing sediment from sticking to the surface of the upper squeeze roller 3 is achieved by installing the knife 7. The porous tape is pressed out, the dewatering process is resumed and proceeds as described. The dehumidified sediment is removed from the tape in its upper part with a knife 7 and collected in the container 9. At the lower part of the tape the sediment is removed by the knife 7, falls on the surface of the guide roller 2, from where it is sent to the container 9. The filtrate is collected in the container 8. Regeneration of the filter belt occurs due to the filtration of the filtrate in the place where the belt passes through the squeezing rollers 3 and 4. In the upper part of the belt, the lower part of its surface is regenerated, which is not in contact with the sediment at the moment, and in the lower part - another part of the surface. Ribhons

Example 1. It has been established that it is most effective to remove the filtrate from a porous tape at the moment of its compression by squeezing rollers, provided that the surface of the lower one with respect to the tape is perforated.

So, when dewatering a mixture of sediment primary settlers and active

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In the sewage treatment plant, the volume of the filtrate when the tape was pressed with rollers with a continuous surface amounted to 550 ml, and when the lower squeezing roller was replaced with a roller with a perforated surface, the volume of the filtrate increased to 680 mp due to the filtrate outflow both along the roller surface and through it.

EXAMPLE 2: It has been found that to effectively separate the filtrate from the porous tape, the ratio of the diameter of the lower squeeze rollers to the diameter of the upper rollers should be 1.5-2.

So, when dewatering a mixture of sediment of primary sedimentation tanks and activated sludge of sewage treatment facilities, the ratio of the diameters of the lower and upper squeezing rollers 1: 1 the volume of leachate filtrate was 720 ml, and the moisture content of the dehydrated sludge was 80.3%.

1 10 cm / g the most appropriate duration of dehydration is 6. S, while the moisture content of the dehydrated sludge is 70.1%, and the productivity is 101 kg / m.h. By reducing the duration to 5 s, the humidity of the sludge has increased to 73.4 % and the productivity decreased to 94 kg / cm h. The increase in the duration to 7 s also reduced the effect of dehydration. The humidity of the sediment was 72.3%, and the productivity - 95. ,

When dewatering a mixture of pre-compacted activated sludge and raw sludge treatment plants

ten

15

With an increase in the ratio of the diameters of the lower and upper rollers to 1.5: 1 and 2: 1, the volume of the filtrate and the moisture content of the dewatered sludge were respectively 790 and 910 ml, 77.1 and 75.4% due to the increase in pressure exerted on the porous ribbon by the upper squeezing roller. . The ratio of the roller diameters of 2.5: 1 did not lead to an increase in the effect, the filtrate volume and the moisture content of the sediment were 910 ml and 77.0%, respectively, and the precipitate was simultaneously pressed into the tape due to the high pressure generated by the upper roller. In addition, an excessively high pressure on the filter belt leads to its rapid wear,

PRI me R 3. It has been established that since 20 it is the most rational to increase productivity, the duration of dewatering is equal to that the thickness of the porous elastic is 300 seconds, at which the moisture content of the filtering belt must have been dehydrated. 4 / 5-9 / 10 of the height is 85.8%, and the productivity is 0.42 kg / layer of sediment on it. Reducing the thickness by 25 hours. Reducing the length of our belt in relation to the dewatering sediment layer to 290 s increased the moisture below the specified ratio leads to a decrease in the performance of the device.

For example, when sludge dewatering, the front also increased the moisture content of the sediment to the primary sedimentation tanks of the sewage treatment plants — 86.9% and reduced the productivity

sewage system with a specific filtration resistance of 1000-10 cm / g was the sedimentation of the sediment to 86.5% and reduced performance to 0.39 kg / m. h. Increase duration up to 310 s

The SRI of sewage capacity on the initial draft of the device with a filter belt thickness of 5 cm and a height of 6 cm of sediment on it was 2 m / h, and the moisture content of the dried sediment was 79%. A decrease in the thickness of the tape to 4 cm at the same height of the sediment layer resulted to its spreading over the tape due to a decrease in the water capacity of the porous tape, increase in moisture, sediment to 85.4%, which was eliminated by reducing the performance of the device to 1.3 m / h and establishing the necessary ratio of the thickness of the tape and the sediment layer,

EXAMPLE 4 It has been established that with various indicators of the resistivity of the sediment filtration, there are the most appropriate durations of dewatering, which correspond to the highest productivity of the device and the lowest humidity of the dehydrated sludge.

So, when dehydrating the coagulated raw sludge of the primary settlers of sewage treatment plants with a specific resistance

880834

1 10 cm / g the most appropriate duration of dehydration is 6. S, while the moisture content of the dehydrated sludge is 70.1%, and the productivity is 101 kg / m.h. By reducing the duration to 5 s, the humidity of the sludge has increased to 73.4 % and the productivity decreased to 94 kg / cm h. The increase in the duration to 7 s also reduced the effect of dehydration. The humidity of the sediment was 72.3%, and the productivity - 95. ,

When dewatering a mixture of pre-compacted activated sludge and raw sludge treatment plants

ten

15

the sewage system with a specific filtration resistance of 1000–10 cm / g was the most rational dehydration duration, equal to 300 s, at which the moisture content of the dehydrated sludge was 85.8%, and the productivity — 0.42 kg / h. dehydration to 290 s increased the moisture

sediment density to 86.5% and reduced performance to 0.39 kg / m. h. Increase duration up to 310 s

five

0

five

0

five

up to 0.4 kg / m.4,

In the experiments performed, while reducing the duration of dehydration relative to its most appropriate value, the moisture content of the dewatered sludge increases due to the reduction in the time required for dewatering, and the productivity decreases due to the fact that the sludge does not have time to filter. An increase in the duration of dewatering relative to its most appropriate value causes an overflow of the device’s receiving sludge with the sediment, deterioration of the conditions for its dehydration and, as a result, an increase in the moisture content of the sludge, which can be eliminated only by reducing the amount of sludge supplied

When dewatering sediments with a resistivity of 1000-10 cm / g, their pretreatment is necessary in order to reduce the resistivity,

Table 1 shows comparative indicators of sewage sludge dewatering with a specific resistance (1-1000). 10 ° cm / g.

Table 1

0

five

0

five

0

five

0

five

0

five

From tab. As can be seen in Fig. 1, each value of the sediment resistance corresponds to a certain duration of the process at which the highest productivity and the lowest moisture content of the dried sludge are achieved.

The choice of the duration of the process depending on the value of the resistivity of the sediment in the indicated ranges is made according to the curve shown in FIG. 2. For example, a specific resistance of 50 U cm / g corresponds to a process duration of 42 s, 300.10 cm / g - 120 s, etc.

FIG. 3 is a schematic diagram of a device for controlling the duration of the dewatering process, consisting of a sludge dewatering device 10, a sludge resistivity measurement sensor 11, a control unit 12 and a belt speed limiter 13.

The duration of the process is controlled as follows.

The sediment is fed to the dewatering device 10, the sample of the supplied sludge is fed to the resistivity sensor 11 with the control unit 12. From the sensor 11 of the control unit through the limiter 13

speed of movement tape

in by resistivity is transmitted

to the drive of the dewatering device, with which the filtering time is adjusted by changing the speed of the movement of the filter belt. The belt speed limiter ensures safe operation of the device in terms of dehydration and a decrease in the belt movement speed when it reaches its maximum value calculated for a specific device. The resistivity can be recorded using a laboratory control or an express method using known methods.

The method of dewatering the sediments is carried out as follows.

Dehydration is subjected to a mixture of sediment primary sedimentation tanks and activated sludge moisture content of 97%. The resistivity of the mixture filtration is 10 10 cm / g.

7.13

Dehydration of the precipitation mixture is carried out with simultaneous feeding of the precipitation mixture without preliminary treatment with reagents on the upper and lower branches of the infinite porous medium (tape). In accordance with the established resistivity indicator, the drainage time is 30 seconds,

Indicators of dewatering the sediment mixture at sewage treatment plants with a capacity of 20 thousand

m / day on the proposed and known

methods are given in Table. 2 and 3.

Table

The humidity of the mixture of precipitation of primary sedimentation tanks

and activated sludge,% 97.2 Dose of flocculant,% by weight of dry matter of sediment 0.6

eight

Continuation of table 3

0

five

Filtration resistivity, xy cm / g Production capacity for dry matter of the sludge, kg / mh Duration of dehydration, with Humidity of the dehydrated mixture,% Concentration of dry matter in the filtrate, g / l.

water,

10 10

25 50

65 30

78.6 73.3

0.5 0.3

Not required

The simplified design of the proposed device as compared with the prototype is achieved by using only one strip of porous material, reducing the number of squeezing rollers and the absence of regeneration units for the filtering material,

As a result of the research, the results are shown in Table. 4, when dewatering the sediment mixture of primary sedimentation tanks and activated sludge from the sewage treatment facilities, it was found that to increase the productivity of the device, the crowd of a porous elastic filter belt should be 4/5 - 9/10 of the height of the sediment layer on it. Reducing the thickness of the tape leads to a decrease in the performance of the device, and increasing it does not lead to an increase in productivity.

Table4

55

Claims (3)

1. A method of sludge dewatering, which includes depositing sludge into receiving trays, multiple dehydration due to capillary drying with moisture and filtering out of the filter belt, removing sludge from the filter belt, in order to reduce the moisture of the dewatered sludge, dehydration sediment is carried out at specific ten When dewatering sewage sludge with a specific resistance of less than 1 t U cm / g, the device is inoperable due to the very high sludge water return, requiring a reduction in the duration of dewatering less than 6 s, which leads to a sharp decrease in the dry matter productivity of the sludge and an increase in moisture dehydrated sludge. With the dewatering of sediments with a specific resistivity of more than 1000 10 cm / g and a duration of dehydration of more than 300 s, the device is also inoperative due to the very low productivity and humidity of the dehydrated sludge, which is 86%. PRI me R 5. When sludge dewatering with a specific filtration resistance of 1000–10 cm / g and a process duration of 300 s, the productivity of the device was 0.42 kg / m-hr with the ear substance at a moisture content of the dewatered sludge 85.8%. Increasing the resistivity to 101010 cm / g and the duration of the dehydration to 310 s reduces the productivity to 0.39 cm3. 25 filtration resistance of the original sediment 1 - 1000 "10 cm / g and time 5 both zozhivani 6 - 300 s.  2. A device for sludge dewatering, containing an endless filtering belt, a means for sludge dewatering, consisting of receiving trays located in the upper and lower parts of the filtering belt, squeezing and guide elements installed with the possibility of rotation around the axis, knives for sludge removal and a container for collecting the filtrate and dehydrated sludge, characterized in that, in order to increase the pro- ductivity and simplify the design, the guide elements of the sludge dewatering means are supplied ementami mounted on the filter belt in front of the receiving tray, the tape thickness is 4/5 - 9/10 of the height of the layer Nachod luminant 35 on her draft. 3. The device according to claim 2, about tl and - the fact that the squeezing elements located in the t-skny part of the filter belt, made thirty home moisture, and the moisture content of the dewatered is 40 perforated, while the ratio of sediment increases to 87%. With a capacity of less than 0.4 kg / cm "h and moisture content of the dewatered sludge more than 86%, the device does not work ,. 45 the diameter of the squeezing elements located in the lower part of the filter belt, to the diameter of the squeezing elements in its upper part is (1.5-2.0): 1. filtration resistance of the original sediment 1 - 1000 "10 cm / g and time both zozhivani 6 - 300 s.  2. A device for sludge dewatering, containing an endless filtering belt, a means for sludge dewatering consisting of receiving trays located in the upper and lower parts of the filtering belt, squeezing and guide elements installed for rotation around an axis, knives for removal sludge and a container for collecting filtrate and dehydrated sludge, characterized in that, in order to increase production and simplify the design, the guiding elements of the sludge dewatering means are provided with pressing lementami mounted on the filter belt in front of the receiving tray, the tape thickness is 4/5 - 9/10 of the height of the layer Nachod luminant on her draft. 3. The device according to claim 2, about tl and - the fact that the squeezing elements located in the t-skny part of the filter belt, made perforated, with this ratio the diameter of the squeezing elements located in the lower part of the filter belt, to the diameter of the squeezing elements in its upper part is (1.5-2.0): 1. rooo 900 800 700 600 500 UOO 300 200 100 60 1st 180 оо / JftadoJitfttffrrf / rbffocfrrb, C .Z (.3