CN112939418A

CN112939418A - Sludge dewatering additive and using method thereof

Info

Publication number: CN112939418A
Application number: CN202110115066.5A
Authority: CN
Inventors: 郑宇松; 赖咏梅; 郑翔书
Original assignee: Individual
Current assignee: Chongqing Siji Jinbiao Technology Co ltd
Priority date: 2021-01-27
Filing date: 2021-01-27
Publication date: 2021-06-11
Anticipated expiration: 2041-01-27
Also published as: CN112939418B

Abstract

The invention discloses a sludge dewatering additive, which is characterized in that: comprises a plurality of solid particles, each solid particle is subjected to hydrophobic treatment, and the surface of each solid particle is covered with a hydrophobic layer. The invention also discloses a use method of the sludge dewatering additive, which is characterized by comprising the following steps: the sludge to be dehydrated and the sludge dehydration additive are added according to the following weight portions of 100: (5-50) uniformly mixing and stirring, and dehydrating by using a mechanical dehydration device or a heat drying dehydration device. The sludge dewatering additive and the use method thereof can better avoid the blockage of the water filtering holes of the filter cloth and better help to improve the sludge dewatering efficiency.

Description

Sludge dewatering additive and using method thereof

Technical Field

The invention belongs to the field of municipal sludge, and particularly relates to a sludge dewatering additive and a use method thereof.

Background

The daily sludge produced by a sewage treatment plant with the daily treatment capacity of 40 ten thousand tons is about 400 tons (the sludge is about one thousandth of the sewage treatment capacity), and each urban area with the magnitude of 10 ten thousand of people generally has 1-3 sewage treatment plants with the scale. The sludge is a by-product of treated domestic sewage, has large amount, high water content (more than 80 percent of water content), instability, easy putrefaction and malodor, and contains pathogenic bacteria, parasites, heavy metals and the like which are harmful to human health. At present, sludge is usually dewatered and then treated to be harmless.

The sludge dewatering effect is good, the transport volume of the dewatered sludge is large, the transport cost is lower, and the effect and the benefit of harmless treatment are more ideal. In the prior art, in order to improve the dehydration performance of sludge, before mechanical dehydration of sludge, a proper amount of organic high molecular polymer polyacrylamide (pam), lime powder and the like are generally uniformly added to reduce the specific resistance of the sludge (the specific resistance of the sludge refers to the resistance of unit mass of the sludge on a unit filtration area when the sludge is filtered under a certain pressure, the specific resistance is obtained by comparing the filtration performance of different sludge (or the same sludge added with different amounts of mixing agents), and the larger the specific resistance of the sludge, the poorer the filtration performance is), so that the sludge is easy to dehydrate. However, the organic high molecular polymer polyacrylamide (pam) is a viscous slurry, and is easily attached to the filter cloth to block filter pores, so that the filtering efficiency is influenced.

Based on this, the skilled person needs to consider how to improve the dewatering and filtering effect of the sludge.

Disclosure of Invention

Aiming at the defects of the prior art, the technical problems to be solved by the invention are as follows:

how to provide a sludge dewatering additive which can better avoid the blockage of the water filtering holes of the filter cloth and better help to improve the sludge dewatering efficiency and a using method thereof.

In order to solve the technical problems, the invention adopts the following technical scheme:

the sludge dewatering additive is characterized in that: comprises a plurality of solid particles, each solid particle is subjected to hydrophobic treatment, and the surface of each solid particle is covered with a hydrophobic layer.

Compared with the prior art, the sludge dewatering additive has the advantages that:

1. play a role in better avoiding the blockage of the filter cloth

The sludge dewatering additive comprises a plurality of solid particles, a hydrophobic layer covers the surface of each solid particle, so that the solid particles have hydrophobicity, the solid particles can prevent water from entering the inside of the solid particles, and a water film (the thickness of the water film is about 1-2 water molecule diameters) is formed outside the hydrophobic layer of the solid particles, so that the solid particles can be smoother by the water film, and the specific resistance of sludge is remarkably reduced; and based on the characteristics that solid particles are smoother and have higher fluidity in water, the sludge and the sludge additive are more difficult to attach to filter cloth or water filtering holes, and the effect of better avoiding water filtering blockage is achieved.

2. Good applicability

After the filter cloth is better prevented from being blocked, the sludge dewatering additive is also suitable for all dewatering equipment (such as a vacuum belt conveyor, a centrifugal machine and a filter press) and the dewatering principle thereof.

3. Plays a role in improving the dehydration efficiency

Solid-state particle among the sludge dewatering additive has specific surface area big for solid-state particle can fully carry the adhesion and treat dehydration processing mud (suspended solid), when being driped by filter-pressing or centrifugation like this, a plurality of solid-state particles can more abundant extrusion treat dehydration processing mud (suspended solid), make moisture fully filter out, promote dewatering efficiency.

The use method of the sludge dewatering additive is characterized in that: the sludge to be dehydrated and the sludge dehydration additive are added according to the following weight portions of 100: (5-50) uniformly mixing and stirring, and dehydrating by using a mechanical dehydration device or a heat drying dehydration device.

The application method of the sludge dewatering additive is simple and convenient, and the sludge to be dewatered is added with the sludge dewatering additive and stirred uniformly.

Drawings

Fig. 1 is a schematic block diagram of an application example of the waterproof pulverized coal in embodiment 4 of the present invention.

FIG. 2 is a photograph of a test material in example 5 of the present invention.

FIG. 3 is a photograph of a bench filter centrifuge of example 5 of the present invention.

Fig. 4a and 4b are photographs of the filtrate and filter cake obtained from the first run in example 5 of the present invention.

Fig. 5a and 5b are photographs of the filtrate and filter cake obtained from a second trial in example 5 of the present invention.

Fig. 6a and 6b are photographs of the filtrate and filter cake obtained from a third experiment in example 5 of the present invention.

Fig. 7a and 7b are photographs of the filtrate and filter cake obtained from the fourth trial in example 5 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Example 1 (fly ash):

the sludge dewatering additive comprises a plurality of solid particles, and each solid particle is subjected to hydrophobic treatment so that the surface of the solid particle is covered with a hydrophobic layer.

The solid particles are fly ash, and the particle size of the solid particles is 1.5-2.5 mm.

The hydrophobic treatment process comprises the following steps:

mixing solid particles, calcium carbonate and fatty acid according to the weight ratio of 100: 20: 10, heating the mixture, stirring and stirring the mixture uniformly, wherein the heating temperature is 120 ℃.

In practice, the fatty acid is stearic acid or/and palmitic acid.

In practice, the heating time is less than 30 minutes.

Less than 6 parts by weight of paraffin wax are also added to the mixture.

The sludge to be dehydrated and the sludge dehydration additive are added according to the following weight portions of 100: 5, uniformly mixing and stirring, and dehydrating by using mechanical dehydration equipment or heat drying dehydration equipment.

The fly ash is about 200 yuan per ton, the cost is low, and the use cost can be obviously reduced.

The solid particles with hydrophobic layers prepared in this example were subjected to a performance test according to the method of DB51/172-1993, and the results showed that the hydrophobic rate was 99.1%, and there was no leakage for 4 days under the pressure of 700mm water column; has good hydrophobic property.

The dewatering equipment is a vacuum belt conveyor, and the filter cloth is continuously used for 1 month without obvious adhesion blocks and blockage.

The water content before sludge dehydration is: 85 percent; the water content after dehydration was 11%.

Example 2 (slag):

the present embodiment is different from embodiment 1 in that: the solid particles are slag, and the particle size of the solid particles is 3-4 mm.

Mixing solid particles, calcium carbonate and fatty acid according to the weight ratio of 100: 5: 15, heating the mixture and stirring the mixture evenly, wherein the heating temperature is 130 ℃.

The sludge to be dehydrated and the sludge dehydration additive are added according to the following weight portions of 100: 25 and uniformly mixing and stirring the mixture, and dehydrating the mixture by using mechanical dehydration equipment or heat drying dehydration equipment.

The slag is about 50 yuan per ton, the cost is low, and the use cost can be obviously reduced.

The solid particles with hydrophobic layers prepared in this example were subjected to a performance test according to the method of DB51/172-1993, and the results showed that the hydrophobic rate was 99.2%, and there was no leakage for 4 days under the pressure of 700mm water column; has good hydrophobic property.

The dewatering equipment is a centrifuge, and the filter cloth is continuously used for 1 month without obvious attachment blocks and blockage.

The water content before sludge dehydration is: 80 percent; the water content after dehydration was 12%.

Example 3 (clay):

the present embodiment is different from embodiment 1 in that: the solid particles are clay, and the particle size of the solid particles is 0.5-2 mm.

Mixing solid particles, calcium carbonate and fatty acid according to the weight ratio of 100: 30: 15, heating the mixture and stirring the mixture evenly, wherein the heating temperature is 160 ℃.

The sludge to be dehydrated and the sludge dehydration additive are added according to the following weight portions of 100: 40 and dewatering by a mechanical dewatering device or a heat drying dewatering device after uniformly mixing and stirring.

The clay is about 200 to 300 yuan per ton, the cost is low, and the use cost can be obviously reduced.

The dewatering equipment is a filter press, and the filter cloth is continuously used for 1 month without obvious attached blocks and blockage.

The water content before sludge dehydration is: 82%; the water content after dehydration was 10%.

Example 4 (coal or/and coal fines):

the present embodiment is different from embodiment 1 in that: the solid particles are coal particles or/and coal powder (any kind of coal can be used, including lignite), and the particle size of the solid particles is a mixture of less than 2 mm.

Mixing solid particles, calcium carbonate and fatty acid according to the weight ratio of 100: 15: 8, heating the mixture, stirring uniformly, and finally obtaining the waterproof coal powder particles, wherein the heating temperature is 115 ℃.

The sludge to be dehydrated and the sludge dehydration additive are added according to the following weight portions of 100: 15 and dewatering by a mechanical dewatering device or a heat drying dewatering device after uniformly mixing and stirring.

The tests and calculations were carried out according to the following tests:

from the above, the sludge dewatering method adopting the technical scheme improves the dewatering performance of the sludge; and the prepared dewatered sludge is subjected to coupled combustion, has high heat value and meets the requirements of thermoelectric power generation.

Preferably, the scheme is an optimal implementation scheme, and the technical scheme has the advantages that:

1. sludge dewatering performance improvement

The coal powder can improve the dehydration performance and the heat value of the sludge, but the viscosity of the coal powder is increased after the coal powder absorbs water due to the self-hydrophilicity of the coal powder, and the coal powder is also easily attached to the filter cloth to block the filter holes.

In the prior art, the addition of the fly ash can obtain the minimum sludge water content, but is not beneficial to the subsequent energy utilization of the sludge. Although the addition of the coal powder can improve the heat value, the water content of the sludge is higher than that of the added coal ash. In addition, when the coal powder is easy to absorb moisture and oxidize, the heat value is further reduced. Therefore, the existing sludge dewatering method is not ideal.

The waterproof coal powder particles have strong hydrophobic property and do not absorb water in water. The paint does not absorb moisture, oxidize or spontaneously combust in the air; the heat productivity does not decrease after long-term storage. The evaluation expert committee of the product has the following evaluation opinions: the product has feasible technology and wide market application prospect, fills the blank at home and abroad in the aspects of hydraulic pipeline transportation and lossless storage, and reaches the international leading level.

The waterproof coal dust particles are applied to sludge dehydration to serve as aggregate, the sludge after subsequent dehydration can be better coupled to generate electricity, and the realization of energy utilization is the innovation of the technical scheme.

According to the technical scheme, the waterproof coal dust particles are used as the additive in the sludge to be dewatered, the waterproof coal dust particles not only have the characteristics of low price, developed pore structure, strong hydrophobic property and the like, but also have the characteristic of high calorific value which the coal ash does not have, the waterproof coal dust particles are used for replacing the coal ash to serve as a conditioner, the sludge is conditioned, the dewatering performance of the sludge can be improved, the calorific value of the conditioned sludge can be improved, and the subsequent energy utilization is facilitated. The test proves that:

(1) the waterproof coal dust particles can obviously improve the mechanical dehydration performance of the sludge. When the adding amount of the waterproof coal dust particles is 5g/100mL of sludge, and the particle size is 100-600 mu m, the water content of a filter cake of the original sludge (with the water content of 97%) subjected to vacuum filtration (with the filtration pressure of-0.09 MPa) after the coal dust conditioning is reduced to 31.2% from 75.22% before the conditioning.

(2) After the waterproof coal powder particles are used for conditioning and mechanically dewatering the sludge, the water content of a filter cake is low, the heat value of the filter cake is remarkably improved compared with that of the original sludge, and conditions are created for energy utilization of the sludge.

(3) The mechanism of improving the mechanical dehydration performance of the sludge by the waterproof coal dust particles is mainly shown in that the waterproof coal dust can obviously reduce the specific resistance of the sludge and enhance the hydrophobic performance of the sludge. The sludge with the water content reduced to about 30 percent can be directly obtained after the dehydration by a plate-and-frame dehydrator.

The waterproof pulverized coal particles are stronger in hydrophobicity than the fly ash, meanwhile, the waterproof pulverized coal particles have strong hydrophobic characteristics and more loose and smooth characteristics, so that sludge to be dehydrated and dehydrated is easier to disperse, the waterproof pulverized coal particles do not have viscosity, are not easy to attach to filter cloth to block filter holes, and can be doped in the sludge, so that the self-heating value can be kept not to be reduced, and the heat value of the dehydrated sludge for coupled combustion power generation is improved.

In the embodiment, the sludge to be dehydrated, which is added with the waterproof coal dust particles, is sent to a plate-and-frame dehydrator for dehydration, so that sludge particles with the water content reduced to 30% can be obtained, and if the sludge particles are sent to a solar drying room and the temperature is above 40 ℃ and the humidity is below 15%, the water content of the sludge is reduced to below 10% only after 20 hours of drying treatment. This opens up a new channel for the energy utilization of the sludge.

For example, when the dry basis heating value of the sludge in Chongqing urban areas is between 1000-2000cal/kg and the heating value of the mixed waterproof coal powder particles is above 4500cal/kg, the sludge particles with the water content of 32 percent are obtained by the method, and the heating value is about 2800 cal/kg. The heating value of the sludge particles after being dried in the air or in the drying room can reach more than 3600 cal/kg. The sludge particles can meet the requirement of combustion power generation of a fluidized bed boiler. And meets the requirements of combustion and discharge of power generation equipment such as coal-fired units and the like, and obviously improves the sludge treatment capacity.

2. Improve the loosening property of the sludge and obtain unexpected good technical effect

The sludge doped with a small proportion of waterproof coal powder (particles) is dried, and due to the hydrophobic waterproof coal powder (particles), the sludge becomes loose, the hydrophobicity is obviously enhanced, the viscosity is obviously weakened, compared with the sludge without the waterproof coal powder (particles), the drying time is obviously shortened, and the heat required by drying is obviously reduced.

Meanwhile, based on the promotion of the loose property of the sludge, the sludge is mixed more fully and uniformly with the mixture produced by mixing and grinding coal, and the mixture can be combusted more fully after being pumped and put into a combustion chamber, so that the heat value is high.

3. The brick is more beneficial to subsequent application (burning power generation, burning heating, cement manufacturing and brick making additives), and especially when the brick is used for making bricks, the sintered pulverized coal can be burnt inside the brick and dense pores are generated inside the brick through the generated carbon dioxide, so that the weight of the brick can be reduced, and the brick has better heat insulation effect.

Example 5 (coal or/and coal fines):

this example is different from example 4 in that different tests were conducted to confirm that the sludge dewatering additive of the present invention can improve the dewatering efficiency of sewage. The method specifically comprises the following steps:

1 materials and equipment for test:

1.1 Material name (shown in FIG. 2): concentrated wastewater (2 in the figure, reference numeral 1), solid content: 2 to 3 percent; waterproof coal dust particles (2 in the figure) and waterproof brown coal dust particles (2 in the figure and 3).

1.2 model of experimental centrifuge: TD5G bench filter centrifuge (shown in fig. 3) using 500 mesh filter cloth (not shown).

The test process comprises the following steps:

2.1 first run:

the scheme is as follows: 60g of waterproof coal dust particles (black) were added to 400ml of concentrated sewage.

The results of this test are shown in FIG. 4a (filtrate in the right beaker and filter cake on the left) and FIG. 4b (close-up photograph of the filter cake).

2.2 second run:

the scheme is as follows: 60g of waterproof coal dust particles (black) were added to 300ml of the concentrated sewage.

The results of this test are shown in FIG. 5a (filtrate in the right beaker and filter cake on the left) and FIG. 5b (close-up photograph of the filter cake).

2.3 third run:

the scheme is as follows: 45g of water-proof brown coal dust (brown) was added to 300ml of the concentrated sewage.

The results of this test are shown in FIG. 6a (filtrate in beaker) and FIG. 6b (close-up photograph of filter cake).

2.4 fourth trial:

the scheme is as follows: 40g of water-proof brown coal dust particles (brown) were added to 400ml of concentrated sewage.

The results of this test are shown in FIG. 7a (filtrate in beaker) and FIG. 7b (close-up photograph of filter cake).

First to fourth tests based on the above:

according to experimental observation, this material dehydration is very fast, adopts to add waterproof coal dust particle, and the intensive mixing is even, through filtering centrifuge separation back, the filter cake divide into two-layerly, leans on the filter cloth side for the buggy of more loose big granule, and the top layer is for finer, relatively more glutinous fine particle layer, and whole bed of material is comparatively loose.

The unloading can be completed by basically adopting a narrow scraper and bag pulling mode; after the waterproof brown coal powder particles are added and fully and uniformly stirred, the layering of the filter cake is relatively less obvious, the moisture content of the whole filter cake is higher, and the filter cake looks more like common mud powder; no matter waterproof lignite powder particles or waterproof lignite powder particles are added, the discharging can be completed by adopting a narrow scraper and bag pulling mode, and a model PLD series bag pulling discharging centrifuge is recommended.

Example 6 (calcium carbonate):

the present embodiment is different from embodiment 1 in that: the solid particles are calcium carbonate, and the particle size of the solid particles is 1-4 mm.

The sludge to be dehydrated and the sludge dehydration additive are added according to the following weight portions of 100: 50 and then dehydrating the mixture by a mechanical dehydration device or a heat drying dehydration device after uniformly mixing and stirring. And conveying the sludge dehydrated by the mechanical dehydration equipment into a solar drying room for storage for a preset time.

The hydrophobic treatment process comprises the following steps:

mixing the solid particles and fatty acid according to the weight ratio of 100: 10, heating and stirring uniformly, wherein the heating temperature is 130 ℃.

In practice, the fatty acid is stearic acid or/and palmitic acid.

In practice, the heating time is less than 30 minutes.

In practice, less than 6 parts by weight of paraffin wax are also added to the mixture.

The calcium carbonate is about 200 to 300 yuan per ton, the cost is low, and the use cost can be obviously reduced.

The water content before sludge dehydration is: 85 percent; the water content after dehydration was 12%.

Example 7 (calcium carbonate):

this embodiment is different from embodiment 6 in that: the solid particles are calcium carbonate, and the particle size of the solid particles is 1-4 mm.

The hydrophobic treatment process comprises the following steps:

mixing the solid particles and fatty acid according to the weight ratio of 100: 20, heating and stirring uniformly, wherein the heating temperature is 70 ℃.

The water content before sludge dehydration is: 81 percent; the water content after dehydration was 10.5%.

Example 8 (different hydrophobic material):

this embodiment is different from embodiments 1 to 7 in that:

the hydrophobic material of the hydrophobic layer covered on the surface of the solid particle comprises one or two of organic silicon sodium alkoxide or organic silicon resin. The weight ratio of the hydrophobic material to the solid particles is 2: 100.

the hydrophobic material also comprises calcium carbonate; any unit weight of solid particles: the weight ratio of the calcium carbonate to the hydrophobic material to the coal is 4: 2: 100.

solid particles, water and hydrophobic materials are stirred and mixed into slurry, and then the dry water content is removed. The procedure of removing water adopts drying treatment.

Stirring and mixing the solid particles and the hydrophobic material at the temperature of 100 ℃ for a preset time, and cooling to normal temperature.

The time for stirring and mixing was 4 minutes.

The water content before sludge dehydration is: 86 percent; the water content after dehydration was 12%.

Example 9 (different hydrophobic materials):

the present embodiment is different from embodiment 8 in that:

the hydrophobic material of the hydrophobic layer covered on the surface of the solid particle comprises one or two of organic silicon sodium alkoxide or organic silicon resin. The weight ratio of the hydrophobic material to the solid particles is 30: 100.

the hydrophobic material also comprises calcium carbonate; any unit weight of solid particles: the weight ratio of the calcium carbonate to the hydrophobic material to the coal is 20: 30: 100.

Stirring and mixing the solid particles and the hydrophobic material at 160 ℃ for a preset time, and cooling to normal temperature.

The time for stirring and mixing was 20 minutes.

The water content before sludge dehydration is: 84%; the water content after dehydration was 15%.

The above is only a preferred embodiment of the present invention, and it should be noted that several modifications and improvements made by those skilled in the art without departing from the technical solution should also be considered as falling within the scope of the claims.

Claims

1. The sludge dewatering additive is characterized in that: comprises a plurality of solid particles, each solid particle is subjected to hydrophobic treatment, and the surface of each solid particle is covered with a hydrophobic layer.

2. The sludge dewatering additive according to claim 1, wherein: the solid particles are one or two of fly ash, slag or clay.

3. The sludge dewatering additive according to claim 1, wherein: the solid particles are coal particles or/and coal powder.

4. The sludge dewatering additive according to claim 2 or 3, wherein: the hydrophobic treatment process comprises the following steps:

mixing solid particles, calcium carbonate and fatty acid according to the weight ratio of 100: (0.1-30): (0.1-20) and heating the mixture and stirring the mixture evenly, wherein the heating temperature is 70-160 ℃.

5. The sludge dewatering additive according to claim 4, wherein: less than 6 parts by weight of paraffin wax are also added to the mixture.

6. The sludge dewatering additive according to claim 1, wherein: the solid particles are calcium carbonate.

7. The sludge dewatering additive according to claim 6, wherein: the hydrophobic treatment process comprises the following steps:

mixing the solid particles and fatty acid according to the weight ratio of 100: (0.1-20) and stirring uniformly, wherein the heating temperature is 70-160 ℃.

8. The sludge dewatering additive according to claim 1, wherein: the solid particles have a particle size of less than 5 mm.

9. The method of using a sludge dewatering additive according to claim 1, wherein: the sludge to be dehydrated and the sludge dehydration additive are added according to the following weight portions of 100: (5-50) uniformly mixing and stirring, and dehydrating by using a mechanical dehydration device or a heat drying dehydration device.

10. The method of using a sludge dewatering additive according to claim 9, wherein: and conveying the sludge dehydrated by the mechanical dehydration equipment into a solar drying room for storage for a preset time.