A plate and frame hot water feed press process

Abstract

The application discloses a kind of plate and frame hot water feeding squeezing process, it is related to sludge treatment process, comprising the following steps: S1, sludge is mixed with modified fenton reagent and is handled, and the conditioning sludge is obtained;S2, the conditioning sludge is put into plate and frame filter press;S3, hot water is injected into the plate and frame filter cavity of plate and frame filter press;S4, water is injected to plate and frame diaphragm filter plate, and the diaphragm squeezing dewatering of conditioning sludge is carried out, and the discharge is completed.The application has the effect of reducing the moisture content of sludge.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sludge treatment, in particular to a plate and frame hot water feeding squeezing process. BACKGROUND

[0002] With the development of national economy and the improvement of people's living standards, people's environmental protection consciousness is gradually enhanced, and the proportion of sewage sludge treatment industry in urban development is increasing, accompanied by the increasing of sludge production.

[0003] The largest proportion in the sludge is water, and through certain technology, the sludge can be dewatered to reduce the volume of sludge and reduce the cost of sludge treatment. The existing sludge dewatering treatment generally adopts mechanical dewatering technology, and uses plate and frame filter press to squeeze the sludge to release the water in the sludge.

[0004] However, the water in the sludge also includes bound water and adsorbed water, which is difficult to remove by traditional mechanical dewatering method. If a conditioner is added to change the properties of the sludge, more conditioners need to be added, and the improvement of dewatering effect is limited. Therefore, how to reduce the water content of the sludge becomes an important problem in sludge treatment. SUMMARY

[0005] In order to reduce the water content of the sludge, the present application provides a plate and frame hot water feeding squeezing process.

[0006] The plate and frame hot water feeding squeezing process provided by the present application adopts the following technical scheme:

[0007] A plate and frame hot water feeding squeezing process, comprising the following steps: S1. mixing and treating the sludge with modified Fenton reagent to obtain conditioned sludge; S2. feeding the conditioned sludge into a plate and frame filter press; S3. injecting hot water into the plate and frame filter cavity of the plate and frame filter press; S4. injecting water into the plate and frame diaphragm filter plate to perform diaphragm squeezing dewatering on the conditioned sludge, and completing discharging.

[0008] By adopting the above technical scheme, the present application mixes the sludge with Fenton reagent, and heats the conditioned sludge mixed with hot water in the plate and frame filter press to destroy the extracellular polymeric substance in the sludge, so as to release the large molecular organic matter such as protein and nucleic acid and a large amount of bound water in the extracellular polymeric substance, thereby achieving the purpose of sludge dewatering. Further, the diaphragm squeezing dewatering is performed to further improve the dewatering effect of the sludge. The present application injects hot water into the plate and frame filter press, and uses hot treatment instead of conventional high pressure treatment, which can effectively reduce the energy consumption of squeezing the sludge, and greatly reduce the water content of the sludge discharged from the plate and frame filter press.

[0009] Preferably, in the S1 step, the preparation method of the modified Fenton reagent is: ultrasonic oscillation of 2-4 parts by weight of ferrous sulfate heptahydrate, 1-3 parts by weight of sodium metaaluminate and 10-15 parts by weight of hydrogen peroxide, adjusting the pH to 3-4, and standing to obtain the Fenton reagent.

[0010] By adopting the above technical solution, the application adds sodium metaaluminate in the process of preparing the Fenton reagent, so that the ferrous sulfate heptahydrate and the sodium metaaluminate are uniformly distributed in the hydrogen peroxide, the ferrous ions are mixed with the hydrogen peroxide, and the ferrous ions can promote the production of hydroxyl radicals with strong oxidizing property from the hydrogen peroxide under acidic conditions to condition the sludge, so that the adsorbed water and bound water of the extracellular polymeric substance in the sludge are released, thereby achieving the dewatering of the sludge; meanwhile, the addition of the sodium metaaluminate can promote the release of the bound water and improve the dewatering effect of the sludge.

[0011] Preferably, the ferrous sulfate heptahydrate is modified ferrous sulfate heptahydrate, and the modification method of the modified ferrous sulfate heptahydrate is: stirring and dispersing 5-10 parts by weight of activated carbon, 8-16 parts by weight of chitosan, 1-2 parts by weight of silane coupling agent and 20-30 parts by weight of ethanol, then uniformly stirring 5-15 parts by weight of ferrous sulfate heptahydrate, and then drying after filtration and washing to obtain the modified ferrous sulfate heptahydrate.

[0012] By adopting the above technical solution, the application modifies the ferrous sulfate heptahydrate, adds activated carbon in the modification process, and couples the activated carbon with the ferrous sulfate heptahydrate to make them tightly combined, so that the ferrous sulfate heptahydrate has good adsorption effect; meanwhile, the chitosan is used to modify the ferrous sulfate heptahydrate, and the chitosan is a high polymer material which can reduce the water content of the sludge and reduce the environmental burden after being mixed with the sludge; when the Fenton reagent is used to condition the sludge, the modified ferrous sulfate heptahydrate can also adsorb and analyze the organic substances in the sludge, so that the harmful substances can be reduced during the pressing process of the sludge in the plate and frame filter press, the bacteria in the sludge can be reduced, the peculiar smell in the sludge can be adsorbed, and the environment has good effect.

[0013] Preferably, the weight ratio of the ferrous sulfate heptahydrate, the activated carbon and the silane coupling agent is 1:(0.8-0.9):(0.12-0.15).

[0014] By adopting the above technical solution, when the ferrous sulfate heptahydrate, the activated carbon and the silane coupling agent are in a specific weight ratio, the silane coupling agent can hydrolyze to generate silanol and hydroxyl ions during the dewatering process of the sludge, so as to promote the dewatering of the sludge, improve the flocculation ability of the sludge floc, reduce the water between the bound water and the sludge flocculation, and improve the dewatering performance of the sludge; meanwhile, the activated carbon doped in the ferrous sulfate heptahydrate can adsorb the sludge particles and reduce the bacteria in the sludge, effectively adsorb the peculiar smell in the sludge, and reduce the water content of the sludge.

[0015] Preferably, in the S1 step, the treatment time of the sludge and the Fenton reagent is 1-2h.

[0016] By adopting the above technical scheme, when the sludge is mixed with the Fenton reagent, the moisture content of the sludge is high at this time, and the Fenton reagent needs to use ferrous sulfate heptahydrate as a catalyst in the solution to promote hydrogen peroxide to destroy the extracellular polymer cell structure of the sludge by strong oxidation, thereby promoting the dewatering effect of the sludge. This process needs a certain time to react, and if the time is short, it is easy to lead to poor dewatering effect.

[0017] Preferably, in the S3 step, the temperature of the hot water is 70-80℃, and the injection time of the hot water is 1-2h.

[0018] By adopting the above technical scheme, after the conditioned sludge enters the plate and frame filter press, hot water is injected to increase the temperature of the conditioned sludge, and the dewatering performance of the sludge improves with the increase of the temperature, thereby effectively improving the dewatering performance of the sludge and reducing the moisture content of the sludge.

[0019] Preferably, in the S4 step, the temperature of the water injected into the plate and frame diaphragm filter plate is 30-40℃.

[0020] By adopting the above technical scheme, the temperature of the water injected into the plate and frame diaphragm filter plate is controlled to preheat the plate and frame diaphragm filter plate, so that the plate and frame diaphragm filter plate is not easy to change due to rapid temperature rise, causing shrinkage and deformation; injecting 30-40℃ water can protect the plate and frame diaphragm filter plate.

[0021] Preferably, the pressure of the squeezing dewatering is 1.5-1.8MPa, and the dewatering time is 15-30min.

[0022] Preferably, in the S1 step, the weight ratio of the sludge to the modified Fenton reagent is 100:(2-5).

[0023] By adopting the above technical scheme, the parameters of the plate and frame filter press for squeezing the sludge and the weight ratio of the sludge to the modified Fenton reagent are controlled, which can improve the dewatering effect of the sewage and reduce the moisture content of the sludge.

[0024] In summary, the present application has the following beneficial technical effects:

[0025] 1.The application regulates sludge by mixing sludge with Fenton reagent, mixes and heats sludge with hot water in a plate and frame filter press to destroy extracellular polymers in sludge, thereby releasing macromolecular organic matter such as protein and nucleic acid and a large amount of bound water in extracellular polymers, so as to achieve the purpose of sludge dewatering, and further improves the dewatering effect of sludge by diaphragm pressing dewatering, the application injects hot water into the plate and frame filter press, and uses heat treatment instead of conventional high pressure treatment, which can effectively reduce the energy consumption of pressing sludge, and can greatly reduce the moisture content of the sludge discharged from the plate and frame filter press.

[0026] 2.In the preparation of Fenton reagent, sodium metaaluminate is added to make ferrous sulfate heptahydrate and sodium metaaluminate uniformly distributed in hydrogen peroxide, and ferrous ions are mixed with hydrogen peroxide, and ferrous ions as catalyst can promote hydrogen peroxide to produce hydroxyl radicals with strong oxidizing property to regulate sludge, so as to release the adsorbed water and bound water of extracellular polymers in sludge, thereby achieving the dewatering of sludge; at the same time, sodium metaaluminate is added, and aluminum ions in sodium metaaluminate can promote the release of bound water and improve the dewatering effect of sludge. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the process flow chart of the application. DETAILED DESCRIPTION

[0028] The application will be further described in detail below in combination with examples and comparative examples.

[0029] Example

[0030] Example 1

[0031] A plate and frame hot water feeding pressing process, referring to Figure 1 , comprising the following steps:

[0032] S1. 100 kg of sludge and 2 kg of modified Fenton reagent are put into a stirring tank, mixed and stirred at a temperature of 45℃ for 1h to obtain regulated sludge;

[0033] S2. The plate and frame filter press is connected with the stirring tank through a connecting pipe, a feeding valve for controlling the opening and closing of the connecting pipe is installed on the connecting pipe, the feeding valve is opened, and the regulated sludge is put into the plate and frame filter press;

[0034] S3. Hot water with a temperature of 70℃ is injected into the plate and frame filter cavity of the plate and frame filter press, and the water injection time is 1h;

[0035] S4. Water with a temperature of 30℃ is injected into the plate and frame diaphragm filter plate, and the regulated sludge is diaphragm pressed and dewatered under the condition of a pressure of 1.5MPa, the dewatering time is 15min, and the discharging is completed.

[0036] The preparation method of the modified Fenton reagent is:

[0037] The 2 kg ferrous sulfate heptahydrate, 1 kg sodium metaaluminate and 10 kg hydrogen peroxide are put into an ultrasonic vibrator, ultrasonic oscillation is carried out at a frequency of 50 kHz for 5 min, and then the pH is adjusted to 3, and the Fenton reagent is obtained by standing.

[0038] Example 2

[0039] A plate and frame hot water feeding pressing process, comprising the following steps:

[0040] S1. 100 kg of sludge and 5 kg of modified Fenton reagent are put into a stirring tank, mixed and stirred at a temperature of 45℃ for 1 h to obtain conditioned sludge;

[0041] S2. The plate and frame filter press is communicated with the stirring tank through a connecting pipe, a feeding valve for controlling the opening and closing of the connecting pipe is installed on the connecting pipe, the feeding valve is opened, and the conditioned sludge is put into the plate and frame filter press;

[0042] S3. Hot water at a temperature of 70℃ is injected into the plate and frame filter cavity of the plate and frame filter press, and the water injection time is 1 h;

[0043] S4. Water at a temperature of 30℃ is injected into the plate and frame diaphragm filter plate, and the conditioned sludge is diaphragm pressed and dewatered under a pressure of 1.5 MPa, the dewatering time is 15 min, and the discharging is completed.

[0044] The preparation method of the modified Fenton reagent is:

[0045] The 2 kg ferrous sulfate heptahydrate, 1 kg sodium metaaluminate and 10 kg hydrogen peroxide are put into an ultrasonic vibrator, ultrasonic oscillation is carried out at a frequency of 50 kHz for 5 min, and then the pH is adjusted to 3, and the Fenton reagent is obtained by standing.

[0046] Example 3

[0047] A plate and frame hot water feeding pressing process, comprising the following steps:

[0048] S1. 100 kg of sludge and 5 kg of modified Fenton reagent are put into a stirring tank, mixed and stirred at a temperature of 45℃ for 1 h to obtain conditioned sludge;

[0049] S2. The plate and frame filter press is communicated with the stirring tank through a connecting pipe, a feeding valve for controlling the opening and closing of the connecting pipe is installed on the connecting pipe, the feeding valve is opened, and the conditioned sludge is put into the plate and frame filter press;

[0050] S3. Hot water at a temperature of 70℃ is injected into the plate and frame filter cavity of the plate and frame filter press, and the water injection time is 1 h;

[0051] S4. The plate and frame diaphragm filter plate is injected with water at a temperature of 30 DEG C, and the conditioned sludge is subjected to diaphragm press dewatering under a pressure of 1.5 MPa, with a dewatering time of 15 min, and the discharge is completed.

[0052] The preparation method of the modified Fenton reagent is as follows:

[0053] 2 kg of ferrous sulfate heptahydrate, 1 kg of sodium metaaluminate, and 10 kg of hydrogen peroxide are put into an ultrasonic vibrator, ultrasonic oscillation is carried out at a frequency of 50 kHz for 5 min, then the pH is adjusted to 3, and the Fenton reagent is obtained by standing.

[0054] Example 4

[0055] A plate and frame hot water feeding press process, which is different from that of Example 3, is that the preparation method of the modified Fenton reagent is different: 4 kg of ferrous sulfate heptahydrate, 3 kg of sodium metaaluminate, and 15 kg of hydrogen peroxide are put into an ultrasonic vibrator, ultrasonic oscillation is carried out at a frequency of 50 kHz for 5 min, then the pH is adjusted to 3, and the Fenton reagent is obtained by standing.

[0056] Example 5

[0057] A plate and frame hot water feeding press process, which is different from that of Example 3, is that the ferrous sulfate heptahydrate is replaced by an equal amount of modified ferrous sulfate heptahydrate, and the preparation method of the modified ferrous sulfate heptahydrate is as follows: 5 kg of activated carbon, 8 kg of chitosan, 1 kg of KH550 silane coupling agent, and 20 kg of ethanol are stirred and dispersed at a temperature of 50 DEG C for 10 min, then 5 kg of ferrous sulfate heptahydrate is added and magnetically stirred at a temperature of 70 DEG C for 3 h, after suction filtration, the product is washed with anhydrous ethanol for 2 times, and then placed in a drying oven for drying at a temperature of 70 DEG C, to obtain the modified ferrous sulfate heptahydrate.

[0058] Example 6

[0059] A plate and frame hot water feeding press process, which is different from that of Example 3, is that the ferrous sulfate heptahydrate is replaced by an equal amount of modified ferrous sulfate heptahydrate, and the preparation method of the modified ferrous sulfate heptahydrate is as follows: 10 kg of activated carbon, 16 kg of chitosan, 2 kg of KH550 silane coupling agent, and 30 kg of ethanol are stirred and dispersed at a temperature of 50 DEG C for 10 min, then 15 kg of ferrous sulfate heptahydrate is added and magnetically stirred at a temperature of 70 DEG C for 3 h, after suction filtration, the product is washed with anhydrous ethanol for 2 times, and then placed in a drying oven for drying at a temperature of 70 DEG C, to obtain the modified ferrous sulfate heptahydrate.

[0060] Example 7

[0061] A plate-and-frame hot water feeding press process, which is different from example 6 in that, in the process of preparing modified ferrous sulfate heptahydrate, the input amount of ferrous sulfate heptahydrate is 10 kg, the input amount of activated carbon is 8 kg, and the input amount of silane coupling agent is 1.2 kg.

[0062] Example 8

[0063] A plate-and-frame hot water feeding press process, which is different from example 6 in that, in the process of preparing modified ferrous sulfate heptahydrate, the input amount of ferrous sulfate heptahydrate is 10 kg, the input amount of activated carbon is 9 kg, and the input amount of silane coupling agent is 1.5 kg.

[0064] Example 9

[0065] A plate-and-frame hot water feeding press process, which is different from example 8 in that, in the S3 step, the temperature of the injected hot water is 80℃, and the injection time is 2h.

[0066] Example 10

[0067] A plate-and-frame hot water feeding press process, which is different from example 8 in that, in the S3 step, the temperature of the injected hot water is 50℃, and the injection time is 1h.

[0068] Example 11

[0069] A plate-and-frame hot water feeding press process, which is different from example 8 in that, in the S4 step, water with a temperature of 40℃ is injected into the plate-and-frame diaphragm filter plate.

[0070] Example 12

[0071] A plate-and-frame hot water feeding press process, which is different from example 8 in that, in the S4 step, water with a temperature of 70℃ is injected into the plate-and-frame diaphragm filter plate.

[0072] Example 13

[0073] A plate-and-frame hot water feeding press process, which is different from example 8 in that, in the S4 step, the pressure for press dewatering is 1.8 MPa, and the dewatering time is 30 min.

[0074] Comparative example

[0075] Comparative example 1

[0076] A plate-and-frame hot water feeding press process, which is different from example 3 in that, in the S2 step, the sludge and the Fenton reagent are not subjected to mixing treatment, and are directly fed into the plate-and-frame filter press.

[0077] Comparative example 2

[0078] A plate-and-frame hot water feeding press process, which is different from Example 3 in that in the S3 step, no hot water is injected into the plate-and-frame filter cavity, and high-pressure mud feeding is carried out at a pressure of 2 MPa.

[0079] Comparative Example 3

[0080] A plate-and-frame hot water feeding press process, which is different from Example 3 in that in the S1 step, the modified Fenton reagent is replaced with an equal amount of commercially available Fenton reagent.

[0081] Comparative Example 4

[0082] A plate-and-frame hot water feeding press process, which is different from Example 3 in that in the S1 step, the modified Fenton reagent is replaced with an equal amount of potassium ferrate.

[0083] Comparative Example 5

[0084] A plate-and-frame hot water feeding press process, which is different from Example 3 in that in the S4 step, no water is injected into the plate-and-frame diaphragm filter, and the conditioned sludge is directly subjected to diaphragm press dewatering.

[0085] Performance detection test:

[0086] Moisture content test: 20 kg of sludge cake after discharge in the S4 step in Examples 1-13 and Comparative Examples 1-5 was weighed, dried in a 60°C oven until completely dry, weighed, and the moisture content of the sludge cake obtained in the S4 step was calculated. Each test was performed three times, and the average value was taken.

[0087] Odor test: The odor grade of the sludge cake discharged in the S4 step in Examples 1-13 and Comparative Examples 1-5 was tested using the following method: 1 kg of sludge cake was placed in a clean, dry, and odorless blue cap bottle, the blue cap bottle was tightly closed and placed in a 100°C oven, and heat treated for 2 h. The blue cap bottle was removed, allowed to cool to room temperature naturally, and immediately after opening, the odor in the blue cap bottle was identified by smell and the corresponding grade was recorded.

[0088] Evaluation grade: 1. Not easy to detect; 2. Detectable, but not pungent; 3. Can be obviously detected, but not pungent; 4. Pungent; 5. Very pungent; 6. Unbearable.

[0089] % moisture content off-note rating Example 1 48.8 3 Example 2 49.4 3 Example 3 48.7 3 Example 4 48.3 3 Example 5 44.5 3 Example 6 44.1 2 Example 7 38.9 1 Example 8 38.4 1 Example 9 36.6 1 Example 10 40.4 3.5 Example 11 36.5 1 Example 12 42.3 3.5 Example 13 36.7 1 Comparative Example 1 60.4 3.5 Comparative Example 2 56.9 3.5 Comparative Example 3 55.7 3.5 Comparative Example 4 58.4 3.5 Comparative Example 5 62.3 3.5

[0090] According to the data comparison of embodiments 1-4, the present application can destroy the extracellular polymer in the sludge by mixing the sludge with Fenton reagent and heating the sludge mixed with hot water in a plate and frame filter press, so as to release the macromolecular organic matter such as protein and nucleic acid and a large amount of bound water in the extracellular polymer, thereby achieving the purpose of sludge dewatering, and further improving the dewatering effect of the sludge by using diaphragm pressing. The present application can effectively reduce the energy consumption of pressing sludge by injecting hot water into the plate and frame filter press and using heat treatment instead of conventional high pressure treatment, and can greatly reduce the water content of the sludge discharged from the plate and frame filter press.

[0091] According to the data comparison of embodiments 3 and 5-6, the present application can modify the ferrous sulfate heptahydrate by adding activated carbon and coupling agent to make the activated carbon and the ferrous sulfate heptahydrate tightly combined, so as to make the ferrous sulfate heptahydrate have good adsorption effect. At the same time, the ferrous sulfate heptahydrate is modified by chitosan, which is a high molecular material. After mixing with sludge, it can reduce the water content of the sludge and reduce the environmental burden. When the Fenton reagent is mixed with the sludge, the modified ferrous sulfate heptahydrate can also adsorb and analyze the organic matter in the sludge, so as to reduce the harmful substances flowing out during the pressing process of the sludge in the plate and frame filter press, reduce the bacteria in the sludge, and adsorb the odor in the sludge, which has good effect on the environment.

[0092] According to the data comparison of embodiments 6-8, when the ferrous sulfate heptahydrate, activated carbon and silane coupling agent are in a specific weight ratio, the silane coupling agent will undergo hydrolysis reaction during the dewatering process of the sludge to generate silanol and hydroxyl ions, which can promote the dewatering of the sludge, improve the flocculation ability of the sludge floc, reduce the water between the combined water and the sludge flocculation, and improve the dewatering performance of the sludge. At the same time, the activated carbon doped in the ferrous sulfate heptahydrate can adsorb the sludge particles while reducing the bacteria in the sludge, effectively adsorbing the odor in the sludge, and reducing the water content of the sludge.

[0093] According to the data comparison of embodiments 8-13, when the sludge is mixed with the Fenton reagent, the water content of the sludge is high at this time, and the Fenton reagent needs to use the ferrous sulfate heptahydrate as a catalyst in the solution to promote the hydrogen peroxide to destroy the extracellular polymer cell structure of the sludge by strong oxidation, so as to promote the dewatering effect of the sludge. This process needs a certain time for reaction, and if the time is too short, it is easy to cause poor dewatering effect.

[0094] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A plate and frame hot water feed press process characterized by: It comprises the following steps: S1. mixing sludge with modified Fenton reagent for treatment, to obtain conditioned sludge; S2. putting the conditioned sludge into a plate-and-frame filter press; S3. injecting hot water into the plate-and-frame filter cavity of the plate-and-frame filter press; S4. injecting water into the plate-and-frame diaphragm filter plate to diaphragm press dewater the conditioned sludge, and completing discharging; In the S1 step, the preparation method of the modified Fenton reagent is: ultrasonic oscillation of 2-4 parts by weight of ferrous sulfate heptahydrate, 1-3 parts by weight of sodium metaaluminate and 10-15 parts by weight of hydrogen peroxide, adjusting pH to 3-4, and standing to obtain the Fenton reagent; The ferrous sulfate heptahydrate is modified ferrous sulfate heptahydrate, and the modification method of the modified ferrous sulfate heptahydrate is: stirring and dispersing 5-10 parts by weight of activated carbon, 8-16 parts by weight of chitosan, 1-2 parts by weight of silane coupling agent and 20-30 parts by weight of ethanol, then adding 5-15 parts by weight of ferrous sulfate heptahydrate and stirring uniformly, suction filtration, washing and drying to obtain the modified ferrous sulfate heptahydrate; In the S3 step, the temperature of the hot water is 70-80℃, and the injection time of the hot water is 1-2h. In the S4 step, the temperature of the water injected into the plate-and-frame diaphragm filter plate is 30-40℃.

2. A plate and frame hot water feed press process according to claim 1 characterised in that: The weight ratio of the ferrous sulfate heptahydrate, activated carbon and silane coupling agent is 1: (0.8-0.9): (0.12-0.15).

3. A plate and frame hot water feed press process according to claim 1, characterized in that: In the S1 step, the treatment time of the sludge with the Fenton reagent is 1-2h.

4. A plate and frame hot water feed press process according to claim 1, characterized in that: The pressure of the press dewatering is 1.5-1.8MPa, and the dewatering time is 15-30min.

5. A plate and frame hot water feed press process according to claim 1 wherein In the S1 step, the weight ratio of the sludge to the modified Fenton reagent is 100: (2-5).

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