1. A sludge ultrasonic wall breaking pretreatment method is characterized in that: the method comprises the following steps:

s1: discharging the sludge in the biological tank into a secondary sedimentation tank for static sedimentation, and then discharging the deposited sludge into a stirring device;

s2: heating the sludge discharged from the S1 by a heater of the stirring device, stirring the sludge by a stirrer, and then discharging the heated and stirred sludge into the ultrasonic air flotation device;

s3: carrying out ultrasonic wall breaking treatment on the sludge by an ultrasonic air flotation device; then, carrying out air floatation treatment on the sludge through an air floatation mechanism, and discharging turbid liquid at the top of the sludge through a paddle; then the treated sludge is subjected to static sedimentation, supernatant is supplemented to the biological pond, and the residual sludge is discharged into a dewatering centrifuge;

s4: and (4) dehydrating and centrifuging the sludge through a dehydrating centrifuge, then replenishing the supernatant to the biological pond, and delivering the residual sludge to a dehydrator for deep dehydration.

2. The ultrasonic wall breaking pretreatment method for sludge according to claim 1, characterized in that: the heating temperature in S2 is 65-70 ℃, and the heating time is 1.8-2.0 hours.

3. The ultrasonic wall breaking pretreatment method for sludge according to claim 1, characterized in that: the ultrasonic intensity in S3 is 0.9-1.0W/L, and the ultrasonic time is 8-10 minutes.

4. The ultrasonic wall breaking pretreatment method for sludge according to claim 1, characterized in that: adding polyaluminium into the sludge in the S3 after ultrasonic treatment, wherein the density of the polyaluminium is 1-1.15 g/cm³And the amount of the polyaluminium chloride added in each liter of sludge is 0.18-0.20 g.

5. A sludge ultrasonic wall breaking pretreatment method is characterized in that: comprises a secondary sedimentation tank, a stirring device and an ultrasonic air floatation device;

one end of the secondary sedimentation tank is communicated with the biological tank, and the other end of the secondary sedimentation tank is communicated with the stirring device through a first pipeline;

a stirrer is arranged in the stirring device, a heater is arranged on the side wall of the stirring device, and the stirring device is communicated with the ultrasonic air flotation device through a second pipeline;

the ultrasonic floatation device is provided with an ultrasonic generator, the lower end in the ultrasonic floatation device is provided with a floatation mechanism, and the upper end in the ultrasonic floatation device is provided with a paddle for skimming turbid liquid on the top of sludge; the upper part of the ultrasonic device is communicated with the biological tank through a first return pipeline and is used for replenishing the sludge supernatant to the biological tank.

6. The ultrasonic wall-breaking pretreatment method for sludge according to claim 5, characterized in that: and the ultrasonic air flotation device is communicated with a medicine adding tank for adding polyaluminium.

7. The ultrasonic wall-breaking pretreatment method for sludge according to claim 5, characterized in that: and the first pipeline is provided with a first centrifugal pump which is used for pumping the sludge into the stirring device from the secondary sedimentation tank.

8. The ultrasonic wall-breaking pretreatment method for sludge according to claim 5, characterized in that: the second pipeline is provided with a second centrifugal pump for pumping sludge into the ultrasonic air floatation device; one end of the second pipeline is communicated with the lower end of the stirring device, and the other end of the second pipeline is communicated with the upper end of the ultrasonic air flotation device.

9. The ultrasonic wall-breaking pretreatment method for sludge according to claim 5, characterized in that: the lower end of the ultrasonic device is communicated to a dewatering centrifugal machine through a fourth pipeline, and one end of the dewatering centrifugal machine is communicated with the biological pond through a second return pipeline and used for replenishing the biological pond with the supernatant.

10. The ultrasonic wall-breaking pretreatment method for sludge according to claim 9, characterized in that: two overflow ports for turbid liquid to flow out are arranged on the side wall of the ultrasonic air floatation device from top to bottom, and the two overflow ports are connected to a third pipeline for discharging the turbid liquid.

Background

With the rapid development of the economy and the acceleration of the urbanization of China, the discharge amount of urban domestic sewage is increased year by year, and the sewage treatment amount of urban sewage treatment plants and the total amount of residual sludge generated correspondingly are also increased continuously. The residual sludge has complex components, mainly consists of microorganisms, organic and inorganic substances, and may be accompanied by toxic and harmful substances such as organic pollutants, heavy metals and the like, and if the residual sludge is discharged randomly without treatment, the environment is seriously polluted. The overall requirements for sludge treatment are stabilization, harmlessness, and reduction. The sludge reduction method mainly comprises two methods, namely, the method for reducing the amount of organic matters (digestion and incineration) and the method for reducing the water content of the sludge (concentration, dehydration, drying and incineration), wherein the second method is simpler and easier than the first method. The organic matter resources such as protein in the excess sludge are abundant (30-60%), and the potential for recycling is large.

In the sewage treatment industry, there are several problems:

1. the problem of insufficient carbon source of inlet water is solved by adding sodium acetate into a biological tank to enhance the denitrification effect of the biological tank, so that the cost of the medicament is high, and the trouble of cost saving and efficiency improvement of a water plant is caused.

2. After the ultrasonic wall breaking treatment is carried out on the sludge, the TP is increased greatly, the TP content of clear liquid is high, and the system is influenced by using a back-supplementing biological pool as a carbon source.

3. In the existing sludge treatment technology, the excess sludge is dehydrated to 80% through a sludge pump room, a large amount of sludge conditioner is usually required to be added for treatment, and the operation cost is increased.

4. In the existing sludge treatment technology, the supernatant is not effectively treated, so that not only is the resource utilization insufficient, but also the sludge concentration effect is influenced.

Disclosure of Invention

The invention aims to provide a sludge ultrasonic wall breaking pretreatment system and a treatment method, and aims to solve the problems that the sludge dewatering performance is insufficient and the TP content in a sludge clear solution is high in the existing sludge treatment technology.

In order to achieve the purpose, the invention adopts the following technical scheme: an ultrasonic wall breaking pretreatment method for sludge comprises the following steps:

s1: discharging the sludge in the biological tank into a secondary sedimentation tank for static sedimentation, and then discharging the deposited sludge into a stirring device;

s2: heating the sludge discharged from the S1 by a heater of the stirring device, stirring the sludge by a stirrer, and then discharging the heated and stirred sludge into the ultrasonic air flotation device;

s3: carrying out ultrasonic wall breaking treatment on the sludge by an ultrasonic air flotation device; then, carrying out air floatation treatment on the sludge through an air floatation mechanism, and discharging turbid liquid at the top of the sludge through a paddle; then the treated sludge is subjected to static sedimentation, supernatant is supplemented to the biological pond, and the residual sludge is discharged into a dewatering centrifuge;

s4: and (4) dehydrating and centrifuging the sludge through a dehydrating centrifuge, then replenishing the supernatant to the biological pond, and delivering the residual sludge to a dehydrator for deep dehydration.

More preferably, the heating temperature in S2 is 65-70 ℃ and the heating time is 1.8-2.0 hours.

More preferably, the ultrasonic intensity in S3 is 0.9-1.0W/L, and the ultrasonic time is 8-10 minutes.

Further preferably, polyaluminium is added to the sludge in the S3 after ultrasonic treatment, the density of the polyaluminium is 1-1.15 g/cm3, and the amount of the polyaluminium added to each liter of the sludge is 0.18-0.2 g.

An ultrasonic wall breaking pretreatment method for sludge comprises a secondary sedimentation tank, a stirring device and an ultrasonic air flotation device;

one end of the secondary sedimentation tank is communicated with the biological tank, and the other end of the secondary sedimentation tank is communicated with the stirring device through a first pipeline;

a stirrer is arranged in the stirring device, a heater is arranged on the side wall of the stirring device, and the stirring device is communicated with the ultrasonic air flotation device through a second pipeline;

the ultrasonic floatation device is provided with an ultrasonic generator, the lower end in the ultrasonic floatation device is provided with a floatation mechanism, and the upper end in the ultrasonic floatation device is provided with a paddle for skimming turbid liquid on the top of sludge; the upper part of the ultrasonic device is communicated with the biological tank through a first return pipeline and is used for replenishing the sludge supernatant to the biological tank.

Preferably, the ultrasonic air flotation device is communicated with a chemical adding tank for adding polyaluminium.

Further preferably, the first pipeline is provided with a first centrifugal pump for pumping the sludge from the secondary sedimentation tank into the stirring device.

Preferably, a second centrifugal pump for pumping sludge into the ultrasonic air flotation device is arranged on the second pipeline; one end of the second pipeline is communicated with the lower end of the stirring device, and the other end of the second pipeline is communicated with the upper end of the ultrasonic air flotation device.

Preferably, the lower end of the ultrasonic device is communicated to a dewatering centrifuge through a fourth pipeline, and one end of the dewatering centrifuge is communicated with the biological pond through a second return pipeline and used for replenishing the biological pond with the supernatant.

Preferably, the side wall of the ultrasonic air flotation device is provided with two overflow ports for allowing turbid liquid to flow out up and down, and the two overflow ports are connected to a third pipeline for discharging the turbid liquid.

Has the advantages that: an ultrasonic wall breaking pretreatment method for sludge comprises the steps of firstly discharging sludge in a biological tank into a settling zone, and performing static settling on the sludge through a secondary settling tank; then stirring and heating the sludge through a stirring area; then an ultrasonic air flotation device of an ultrasonic air flotation zone is used for carrying out ultrasonic wall breaking and air flotation treatment on the sludge; then standing and settling and replenishing the supernatant to the biological pond; and (4) treating the excess sludge through a dehydration centrifugal area, then replenishing the supernatant to a biological pond to be used as a carbon source, and conveying the excess sludge out to a dehydrator for deep dehydration.

Carrying out ultrasonic wall breaking on the heated and stirred sludge to increase the COD of the original sludge supernatant from 40mg/L to 1500mg/L and increase the COD content by 37.5 times;

the sludge after wall breaking is pre-concentrated and dehydrated, the solid content is increased from 1% to 8%, which shows that the dehydration performance of the sludge is effectively improved by the thermal hydrolysis and ultrasonic wall breaking method;

after ultrasonic wall breaking, the COD and TP contents in the clear sludge liquid are obviously increased. After polyaluminium is added and air floatation treatment is carried out, TP is effectively removed, the total phosphorus content is reduced by about 80 percent, COD is fully released from the bottom mud, and the COD content is increased by 20 percent;

by adopting the ultrasonic wall-breaking pretreatment method for the sludge, free water, adsorbed water and bound water in the sludge can be effectively removed, the dehydration performance of the sludge is effectively improved, the sludge is easier to compress, and mud cakes are more compact;

by adopting the ultrasonic wall-breaking pretreatment method for the sludge, the resource utilization of the excess sludge is realized, organic matters in the excess sludge are reused, and the method can be used as a supplementary carbon source for an anoxic section of a biological pond to enhance the denitrification effect. The sludge dewatering performance is improved, the water content is easier to reduce, and the method is a way for realizing sludge reduction;

by adopting the ultrasonic wall-breaking pretreatment method for the sludge, disclosed by the invention, on one hand, the supernatant is used as an organic carbon source, so that the supplement of the carbon source in the process operation is saved; on the other hand, the concentrated sludge is easier to dehydrate, and the dosage of a sludge conditioner (polyacrylamide) of a subsequent dehydrator is reduced.

Drawings

FIG. 1 is a schematic structural diagram of a sludge ultrasonic wall-breaking pretreatment system according to the present invention;

FIG. 2 is a flow chart of the ultrasonic wall-breaking pretreatment method for sludge according to the present invention.

Names corresponding to the marks in the figure: 1. the device comprises a secondary sedimentation tank, 11, a first pipeline, 12, a first centrifugal pump, 2, a stirring device, 21, a stirrer, 22, a heater, 23, a second pipeline, 231, a second centrifugal pump, 3, an ultrasonic air floatation device, 30, a medicine adding tank, 31, an ultrasonic generator, 32, an air floatation mechanism, 321, an air compressor, 33, blades, 34, an overflow port, 35, a first backflow pipeline, 36, a third pipeline, 37, a fourth pipeline, 4, a dewatering centrifugal machine, 41, a second backflow pipeline, 42 and a fifth pipeline.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

Example (b): as shown in figure 1, the ultrasonic wall-breaking pretreatment system for sludge comprises a secondary sedimentation tank 1, a stirring device 2, an ultrasonic air flotation device 3 and a dewatering centrifuge 4. One end of the secondary sedimentation tank 1 is communicated with the biological tank and is used for receiving sludge discharged from the biological tank. The lower end of the secondary sedimentation tank 1 is communicated with the stirring device 2 through a first pipeline 11, and a first centrifugal pump 12 is arranged on the first pipeline 11 and used for pumping the sludge in the secondary sedimentation tank 1 into the stirring device 2.

A stirrer 21 is arranged in the stirring device 2, a heater 22 is arranged on the side wall of the stirring device 2, and in the process of stirring sludge, the sludge is uniformly heated through stirring of the stirrer 21, and meanwhile, the heating speed is increased; the lower end of the stirring device 2 is communicated with the ultrasonic air flotation device 3 through a second pipeline 23, a second centrifugal pump 231 is arranged on the second pipeline, and the heated sludge is pumped into the ultrasonic air flotation device 3 through the second centrifugal pump 231.

An ultrasonic generator 31 is arranged on the ultrasonic air flotation device 3, a medicine adding tank 30 for adding polyaluminium is communicated on the ultrasonic air flotation device 3, and the circulation between the medicine adding tank 30 and the ultrasonic air flotation device 3 is controlled by a control valve. The lower end of the inside of the ultrasonic air flotation device 3 is provided with an air flotation mechanism 32, the upper end is provided with a paddle 33 for skimming turbid liquid at the top end of the sludge, and the air flotation mechanism 32 is controlled by an air compressor 321. Through the work of ultrasonic generator 31, carry out ultrasonic broken wall processing to the mud in the supersound air supporting device 3, later carry out air supporting processing to mud through air supporting mechanism 32.

Because the sedimentation ratio is different in summer and winter, and the sedimentation ratio is different, the liquid level of the supernatant is also different, in order to skim the turbid liquid on different liquid level heights, two overflow ports 34 are arranged up and down and are connected to the third pipeline 36, and the turbid liquid is discharged from the third pipeline 36 by controlling the valves on the two overflow ports 34. The upper part of the ultrasonic air flotation device 3 is communicated with a first return pipeline 35, the other end of the first return pipeline 35 is communicated with the biological tank, and supernatant in the ultrasonic air flotation device 3 is returned to the biological tank through the first return pipeline 35 to serve as a carbon source.

The lower end of the ultrasonic air flotation device 3 is communicated with a fourth pipeline 37, the other end of the fourth pipeline 37 is communicated with the dewatering centrifuge 4, and the sludge is discharged into the dewatering centrifuge 4 through the fourth pipeline 37; the fourth pipeline 37 is provided with a control valve, the sludge in the ultrasonic air flotation device 3 is controlled by the control valve to flow into the dewatering centrifuge 4, and then the sludge is dewatered and centrifuged by the dewatering centrifuge 4. The dewatering centrifuge 4 is communicated with a second return pipeline 41 and a fifth pipeline 42, wherein the second return pipeline 41 is communicated with the biological tank and is used for returning the supernatant after dewatering and centrifuging to the biological tank; the fifth pipe 42 is used to discharge excess sludge to the dehydrator for deep dehydration. Since the supernatant is removed before entering the dewatering machine, the sludge in the dewatering machine is easier to concentrate.

As shown in fig. 2, the ultrasonic wall breaking pretreatment method for sludge comprises the following steps:

s1: and (3) injecting the sludge suspension in the biological tank into the secondary sedimentation tank 1 for static sedimentation, then controlling the first centrifugal pump 12 to work, and pumping the sludge into the stirring device through the first pipeline 11.

S2: controlling a heater 22 in the stirring device 2 to work, and heating the sludge discharged from S1 at the heating temperature of 70 ℃ for 2.0 hours; meanwhile, the stirrer 21 is used for stirring the sludge, so that the heating speed can be increased, and the sludge can be uniformly heated; after the heating is finished, the heater 22 is controlled to stop heating, then the second centrifugal pump 231 is started to work, and the sludge after being heated and stirred is discharged into the ultrasonic air flotation device through the second pipeline 23.

S3: and starting the ultrasonic generator 31 to enable the ultrasonic air flotation device 3 to carry out ultrasonic wall breaking treatment on the sludge, wherein the ultrasonic intensity is 1.0W/L, and the ultrasonic time is 10 minutes. After the ultrasonic treatment is finished, the ultrasonic generator 31 is closed, the control valve of the medicine adding tank 30 is opened, and polyaluminium is added into the sludge after the ultrasonic treatment, wherein the density of the polyaluminium is 1.15g/cm³The amount of polyaluminium added per liter of sludge is 0.20 g. The COD and TP content in clear liquid of the sludge subjected to the ultrasonic wall breaking treatment are obviously increased; then, the air compressor 321 is controlled to work, so that the air floatation mechanism 32 performs air floatation treatment on the sludge; meanwhile, the paddle 33 rotates to discharge turbid liquid at the top of the sludge, so that the content of P in clear liquid can be effectively reduced, and the air compressor 321 is turned off after air floatation treatment is finished. The treated sludge is then allowed to settle and the supernatant is fed back to the biological tank via a first return conduit 35. And controls the control valve on the fourth pipe 37 to open, and discharges the surplus sludge to the dewatering centrifuge 4 through the fourth pipe 36 for processing.

S4: the sludge discharged from S3 is dewatered and centrifuged by the dewatering centrifuge 4, and then the supernatant is returned to the biological pond via the second return line 41 as a carbon source, and the excess sludge is sent out to the dewatering machine via the fifth line 42 for deep dewatering.

Through heating and ultrasonic wall breaking treatment, the substances in the microbial cells in the sludge are released, hydroxyl radicals and soluble COD are dissolved in water, the COD of the supernatant of the original sludge is increased from 40mg/L to 1500mg/L, the COD content is increased by 37.5 times, but the TP content in the supernatant is also obviously increased. Adding polyaluminium, and effectively removing the TP content in the sludge clear liquid through air floatation treatment, wherein the TP removal rate reaches about 80%; and through air floatation treatment, COD is fully released from the sludge, and the COD content in the clear liquid is increased by 20 percent. In addition, after the sludge is heated, the ultrasonic air flotation treatment is carried out, and the supernatant is supplemented again, so that the concentration performance of the residual sludge is improved, and in the subsequent centrifugal machine treatment, the solid content of the sludge is increased from 1% to 8%, so that the resources can be effectively utilized, the sludge concentration effect can be improved, and the dosage of a sludge conditioning agent is reduced.

In the above embodiment, the temperature of the heat treatment can be adjusted to 65 ℃, the heating time can be 1.8 hours, the ultrasonic intensity can be adjusted to 0.9W/L, the ultrasonic time can be adjusted to 8 minutes, and the obtained effect is similar to the above effect; the added polyaluminium may also have a density of 1.0g/cm³The amount of the phosphorus removal agent added per liter of sludge is 0.18g, and the phosphorus removal effect is not greatly different, so that the detailed description is omitted.

The present invention is not limited to the above-mentioned preferred embodiments, and any other products in various forms can be obtained by anyone in the light of the present invention, but any changes in the shape or structure thereof, which have the same or similar technical solutions as those of the present application, fall within the protection scope of the present invention.