Sludge treatment method combining biological treatment and high-pressure thin-layer filter pressing

Abstract

The invention discloses a biological treatment and high-pressure thin-layer filter pressing combined sludge treatment method, and relates to the technical field of sludge resource utilization, and the method comprises the following steps: (1) uniformly mixing sludge and a thermophilic microbial agent, and putting the mixture into biological treatment equipment for aerobic pretreatment; and (2) conveying the pretreated sludge into high-pressure thin-layer filter pressing equipment for filter pressing. The sludge structure is destroyed through biological treatment, the water form of the sludge is changed, and the bottleneck of tight combination of water and sludge particles in the filter pressing process is solved; in the whole treatment process, additional heating is not needed, chemicals are not added, fermentation treatment is conducted on the sludge only through metabolic activity of thermophilic microorganisms, the sludge treatment cost is reduced, and finally waste of the sludge is turned into wealth.

Description

Technical Field

[0001] The invention relates to the technical field of sludge resource utilization, and in particular to a sludge treatment method combining biological treatment with high-pressure thin-layer filter press. Background Art

[0002] Sludge is a by-product of sewage treatment. Its main sources are refractory organic matter, microbial metabolites and some parasite eggs in sewage. If not treated in time, it will easily breed bacteria and emit a foul smell, which will not only pollute the environment, but also cause great harm to people's physical and mental health. The "Ten Water Regulations" clearly point out that sludge treatment is an important part of the comprehensive control of pollutant emissions in the future. Sludge dewatering is an important step to achieve sludge reduction, resource utilization and harmlessness. It determines the final sludge treatment cost and the choice of final disposal method, and is the most important process link in the sludge treatment process. However, the sludge treatment cost is high, generally accounting for 25-40% of the operating costs of sewage treatment plants, which seriously restricts the sustainable and stable development of sewage treatment plants and brings a heavy economic burden to the daily maintenance and operation of sewage treatment plants. In addition, carbon emissions from the sewage treatment industry account for 1-2% of the total emissions of the whole society. In order to achieve the goal of carbon neutrality, sludge disposal is an area of ​​emission reduction that cannot be ignored.

[0003] Sludge biological treatment uses the bioheat generated by the aerobic respiration of thermophilic microorganisms to degrade organic matter, and cooperates with forced ventilation to promote water evaporation, so as to dehydrate the sludge quickly and effectively without adding exogenous heat energy. After the addition of exogenous thermophilic microorganisms, the sludge pile will rise to a high temperature stage within 1 to 3 days. Driven by the degradation of organic matter and the increase in temperature, the microbial metabolism destroys the sludge structure and decomposes the sludge particles. The pores in the sludge increase, and the surface adsorbed water is converted into interstitial water, which reduces the energy required for water removal and promotes the rapid discharge of sludge water. In addition, the whole process is aerobic and ventilated, which greatly reduces the odor emission of sludge. At the same time, microbial metabolism reduces the protein and polysaccharide in the sludge. Protein and polysaccharide are high molecular substances with viscosity and hydrophilicity, which can form a highly hydrated charged floc matrix similar to gel. These polymers embed microorganisms in the flocs by generating viscous forces, maintain the integrity of the floc structure and function, and thus cause the sludge to have greater viscosity. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a sludge treatment method combining biological treatment with high-pressure thin-layer filter pressing, which utilizes biological treatment to destroy the sludge structure, change the sludge water form, and solve the bottleneck of the close combination of water and sludge particles in the filter pressing process; the entire treatment process does not require additional heating or the addition of chemicals, and only utilizes the metabolic activities of thermophilic microorganisms to ferment the sludge, thereby reducing the sludge treatment cost and ultimately realizing the transformation of sludge from waste to treasure.

[0005] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0006] A sludge treatment method combining biological treatment with high-pressure thin-layer filter press comprises the following steps:

[0007] (1) The sludge and the thermophilic agent are mixed evenly and then put into the biological treatment equipment for aerobic pretreatment;

[0008] (2) The pretreated sludge is transported to a high-pressure thin-layer filter press for filtration.

[0009] Furthermore, the water content of the sludge in step (1) is above 80%.

[0010] Furthermore, the aerobic pretreatment in step (1) is carried out under ventilation and stirring conditions, with a ventilation rate of 1 to 4 L·h -1 kg -1 The intermittent ventilation frequency is open 5-30 minutes / closed 10-60 minutes, and the aeration cycle is 30-300 minutes. The fermentation time is 1-3 days.

[0011] Furthermore, the thermophilic agent in step (1) has a tolerance temperature of above 70°C, including but not limited to at least two of Calditerricolayamamurae (extreme thermophilic bacteria), Thermus thermophilus (thermophilic bacteria), Calditerricolasatsumensis (hyperthermophilic bacteria), and Thermaerobacter composti (thermophilic bacteria); the carrier of the thermophilic agent is at least one of rice bran, corn flour, and starch.

[0012] Furthermore, the mass ratio of the sludge to the thermophilic bacteria agent in step (1) is (90-100):(0.5-2).

[0013] In the present invention, step (1) can be "mixing the sludge and the thermophilic agent uniformly and then putting them into the biological treatment equipment for pretreatment", or "mixing the sludge, the sludge after filter pressing and the thermophilic agent uniformly and then putting them into the biological treatment equipment for pretreatment". Preferably, the mass ratio of the sludge to the sludge after filter pressing and the thermophilic agent is 100:(10-20):(0.5-2). Adding the sludge after filter pressing is mainly used to increase the porosity of the pile body and provide oxygen and living space for the metabolism of aerobic bacteria.

[0014] Furthermore, the specific process of the high-pressure thin-layer filter pressing is to evenly arrange the fermented sludge on the filter cloth through the sludge feeding module, and the high-efficiency coating module of the sludge and filter cloth includes a filter cloth self-adaptive system and a thin layer cloth system, and the sludge and filter cloth are combined to form a single-layer sludge structure. Through the forward and backward movement of the arrangement module, the single-layer sludge structure is stacked up and down in the filter press cage in turn to form multiple groups of filter chambers; the sludge high-pressure solidification module includes a high-pressure filter pressing system and a pressing cage, and the high-pressure filter pressing system performs high-pressure extrusion on the stacked sludge modules in the pressing cage.

[0015] Furthermore, the filter cloth self-adaptive system includes filter cloth spreading, cleaning, air drying, cloth correction and detection functions.

[0016] Furthermore, in step (2), the water content of the sludge is reduced to below 60% by filter pressing.

[0017] Furthermore, the volume of the sludge in step (2) is reduced after filtration, and the calorific value is increased. The sludge can be converted into an alternative fuel for cement kilns at a low cost by biological drying using the action of the remaining microorganisms or thermal drying using the waste heat of the cement kiln.

[0018] As a new type of filter pressing process, sludge high-pressure thin-layer filter pressing utilizes the efficient coating of sludge and filter cloth. It forms an efficient filter pressing mechanism based on the uniform distribution shape of the sludge thin layer and high projection pressure without adding additional reagents, thereby reducing investment and operating costs. The entire filter pressing process is automatically controlled, and the filter cloth self-adaptive system includes the functions of spreading, cleaning, air drying, correcting and detecting the filter cloth. The sludge high-pressure solidification module includes a high-pressure filter pressing system and a pressing cage. The high-pressure filter pressing system squeezes the stacked sludge modules in the pressing cage under high pressure, solving the problems of high moisture content of the discharge, large amount of reagent addition and high operating cost in the traditional filter pressing process.

[0019] The present invention utilizes biological treatment combined with high-pressure thin-layer filter press deep dehydration technology to achieve sludge reduction, resource utilization and harmless treatment. The whole process is low-carbon and low-operating cost, producing the following technical effects:

[0020] 1) Rapidly destroy the sludge structure and change the sludge water form. The water carried by the sludge is converted from surface adsorbed water to interstitial water, reducing the bond energy of water and sludge, making it easier to remove the sludge water; 2) Reduce sludge cell damage, avoid the release of hydrophilic substances after sludge wall breaking caused by the high pressure applied by the high-pressure thin-layer filter press section, and reduce the adverse effects of high-pressure filter press on sludge dewatering performance; 3) Reduce the content of polymers such as protein and polysaccharides in the sludge, effectively reduce the viscosity of the sludge, and reduce the viscosity of the sludge and the filter cloth; 4) Promote the degradation of macromolecular organic matter in the sludge EPS and reduce the filtration resistance caused by the accumulation of macromolecular organic matter during high-pressure filter press. The sludge filtered out can also be used to continue to act on the residual microorganisms of biological treatment to biologically dry to a moisture content of less than 40%, or further dried in combination with the waste heat of cement kilns, reducing the requirements and costs for sludge transportation and storage, while greatly improving the calorific value. The finished product can be transported to cement kilns as an alternative fuel.

[0021] The beneficial effects of the present invention are:

[0022] 1. The biological treatment process of the present invention is a high-temperature aerobic fermentation of sludge, which does not require additional heating or the addition of agents. The sludge is fermented only by the metabolic activity of thermophilic microorganisms, thereby reducing the cost of sludge treatment.

[0023] 2. The present invention uses high-pressure thin-layer filter press technology to establish deep sludge dehydration without adding chemicals. The whole process is automatically controlled, the filter press efficiency is high, the system energy consumption is low, and the labor cost is greatly reduced;

[0024] 3. The present invention utilizes biological treatment to destroy the sludge structure and change the sludge water form, thereby solving the bottleneck of large filtration resistance, close combination of water and sludge particles, and difficulty in deep removal of water in the existing filter press process;

[0025] 4. In the present invention, the sludge after biological treatment and high-pressure thin-layer filtration can be further biologically dried by the remaining microorganisms for further metabolism, thereby realizing a closed loop of sludge dehydration; or it can be dried by using the waste heat of the cement kiln and then transported to the cement kiln as an alternative fuel, thereby realizing low-carbon and environmentally friendly sludge treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The SEM images of sludge before and after fermentation;

[0027] Figure 2 is the curve of the average particle size of sludge changing with fermentation time;

[0028] Figure 3 It is a schematic diagram of high-pressure thin-layer filter pressing; wherein, 1-sludge homogenizing device, 2-sludge spreading device, 3-filter pressing device, 4-hydraulic control system, 5-sludge discharge. DETAILED DESCRIPTION

[0029] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments and diagrams.

[0030] The sludge used in the following examples and comparative examples comes from a sewage treatment plant and has a water content of 81.23%.

[0031] The thermophilic bacteria agents in the following examples and comparative examples are all laboratory-made thermophilic bacteria agents, and their preparation methods are as follows:

[0032] The concentration of 10 8 cfu / mL of Calditerricola yamamurae, Thermus thermophilus and Thermaerobacter composti bacterial liquid was inoculated into CYS medium, cultured at 70-75°C for 1-2 days, corn flour and starch (mass ratio of 1:1) were added to the culture liquid with a solid-liquid ratio of 1:1, stirred evenly, and continued to dry at 70-75°C, and the three powders were mixed in a mass ratio of 1:1:1 to obtain a thermophilic agent.

[0033] Example 1

[0034] Add 100 kg of sludge from the sewage treatment plant and 1 kg of thermophilic agent into the mixer, mix well and put into the 600 L biological treatment tank. Set the ventilation volume to 1.6 L h -1 kg -1 (wet weight), the intermittent ventilation frequency is set to open 10min / closed 20min, with 30min as an aeration cycle, and fermentation for 3 days. The fermented sludge is transported to the sludge distributor through the conveying pipeline, and the sludge is evenly arranged on the filter cloth, and the sludge is pressed after multiple layers are stacked, and the pressure is set to 30kg / cm 3 The pressing time was set to 15 min, and the moisture content of the sludge after filtration was 58.64%.

[0035] Figure 1 The SEM images of sludge before and after fermentation. Figure 1 It can be seen that after biological treatment, the tight structure of the sludge is destroyed, part of the surface organic matter is degraded, and the sludge surface becomes loose and porous.

[0036] Figure 2 The curve of the average particle size of sludge changing with fermentation time. Figure 2 It can be seen that as the fermentation time increases, the sludge particles become smaller.

[0037] Example 2

[0038] The method of Example 1 is followed, except that the dosage of the thermophilic agent is adjusted.

[0039] Add 100 kg of sludge from the sewage treatment plant and 0.5 kg of thermophilic agent into the mixer, mix well and put into the 600 L biological treatment tank. Set the ventilation volume to 1.6 L h -1 kg -1 (wet weight), the intermittent ventilation frequency is set to open 10min / closed 20min, with 30min as an aeration cycle, and fermentation for 3 days. The fermented sludge is transported to the sludge distributor through the conveying pipeline, and the sludge is evenly arranged on the filter cloth, and the sludge is pressed after multiple layers are stacked, and the pressure is set to 30kg / cm 3 The pressing time was set to 15 min, and the moisture content of the sludge after filtration was 61.33%.

[0040] Example 3

[0041] The method of Example 1 is followed, except that the conditions of aerobic pretreatment are adjusted.

[0042] Add 100 kg of sludge from the sewage treatment plant and 1 kg of thermophilic agent into the mixer, mix well and put into the 600 L biological treatment tank. Set the ventilation volume to 4 L h -1 kg -1 (wet weight), the intermittent ventilation frequency is set to open 15min / closed 30min, with 45min as an aeration cycle, and fermentation for 1 day. The fermented sludge is transported to the sludge distributor through the conveying pipeline, and the sludge is evenly arranged on the filter cloth, and the sludge is pressed after multiple layers are stacked, and the pressure is set to 30kg / cm 3 The pressing time was set to 15 minutes, and the moisture content of the sludge after filtration was 60.78%.

[0043] Example 4

[0044] The method of Example 1 is followed, except that the sludge after filter pressing is added to the sludge to be treated.

[0045] Add 100 kg of sludge from the sewage treatment plant, 20 kg of sludge after high-pressure thin-layer filtration (water content 61.23%) and 1 kg of thermophilic agent into the mixer, mix well and put into the 600 L biological treatment tank, and set the ventilation volume to 1.6 L h -1 kg -1 (wet weight), the intermittent ventilation frequency is set to open 10min / closed 20min, with 30min as an aeration cycle, and fermentation for 3 days. The fermented sludge is transported to the sludge distributor through the conveying pipeline, and the sludge is evenly arranged on the filter cloth, and the sludge is pressed after multiple layers are stacked, and the pressure is set to 30kg / cm 3 The pressing time was set to 15 min, and the moisture content of the sludge after filtration was 56.83%.

[0046] By comparing Example 1 and Example 4, it can be seen that by adding the sludge after filter pressing, the oxygen content of the pile can be increased, the action of microorganisms can be promoted, the biological treatment effect can be improved, and the filter pressing efficiency can be improved.

[0047] Comparative Example 1

[0048] The method of Example 1 was followed, except that no aerobic pretreatment was performed.

[0049] 100kg of sludge from the sewage treatment plant is transported to the sludge distributor through the conveying pipeline. The sludge is evenly distributed on the filter cloth, and the filter is pressed after multiple layers are stacked. The pressure is set to 30kg / cm 3 The pressing time was set to 15 min, and the moisture content of the sludge after filtration was 65.95%.

[0050] Comparison of Example 1 with Comparative Example 1 shows that aerobic pretreatment of sludge using thermophilic agents can reduce the moisture content of sludge after filter pressing. Biological treatment improves the filter pressing and dewatering performance of sludge by changing the sludge structure, particle size, viscosity and other aspects.

[0051] Comparative Example 2

[0052] The method of Example 1 is followed, except that plate and frame filter pressing is used.

[0053] Add 100 kg of sludge from the sewage treatment plant into the mixer, mix well and put into the 600 L biological treatment tank. Set the ventilation volume to 1.6 L·h-1·kg -1 (wet weight), the intermittent ventilation frequency is set to open 10min / closed 20min, with 30min as one aeration cycle, and fermentation for 3 days. The fermented sludge is transported to the sludge plate and frame filter press through the conveying pipeline, and the pressure is set to 6kg / cm 3 , the time was set to 15min, and the moisture content of the sludge after filtration was 71.95%.

[0054] By comparing Example 1 and Comparative Example 2, it can be seen that the combination of biological treatment and high-pressure thin-layer filter pressing can effectively improve the filter pressing effect and deeply reduce the moisture content of the sludge.

[0055] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A sludge treatment method combining biological treatment with high-pressure thin-layer filter press, characterized in that: The following steps are involved: (1) The sludge and the thermophilic agent are mixed evenly and then put into the biological treatment equipment for aerobic pretreatment; (2) The pretreated sludge is transported to a high-pressure thin-layer filter press for filtration.

2. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 1 is characterized in that: The water content of the sludge in step (1) is above 80%.

3. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 1 is characterized in that: The aerobic pretreatment in step (1) is carried out under ventilation and stirring conditions, with a ventilation rate of 1 to 4 L·h -1 kg -1 The intermittent ventilation frequency is open 5-30 minutes / closed 10-60 minutes, and the aeration cycle is 30-300 minutes. The fermentation time is 1-3 days.

4. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 1 is characterized in that: The thermophilic agent in step (1) has a tolerance temperature of above 70° C. and comprises at least two of Calditerricolayamamurae, Thermus thermophilus, Calditerricolasatsumensis, and Thermaerobactercomposti; and the carrier of the thermophilic agent is at least one of rice bran, corn flour, and starch.

5. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 1 is characterized in that: The mass ratio of the sludge to the thermophilic bacteria agent in step (1) is (90-100):(0.5-2).

6. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 1, characterized in that: The step (1) is replaced by "mixing the sludge, the sludge after filter pressing and the thermophilic agent uniformly and then putting them into the biological treatment equipment for aerobic pretreatment"; preferably, the mass ratio of the sludge, the sludge after filter pressing and the thermophilic agent is 100:(10-20):(0.5-2).

7. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 1 is characterized in that: The specific process of the high-pressure thin-layer filter pressing is to evenly arrange the fermented sludge on the filter cloth through the sludge feeding module, and the efficient coating module of the sludge and the filter cloth includes a filter cloth self-adaptive system and a thin-layer cloth system, and the sludge and the filter cloth are combined to form a single-layer sludge structure. Through the forward and backward movement of the arrangement module, the single-layer sludge structure is sequentially stacked up and down in the filter press cage to form multiple groups of filter chambers; The sludge high-pressure solidification module includes a high-pressure filter press system and a pressing cage. The high-pressure filter press system squeezes the stacked sludge modules in the pressing cage under high pressure.

8. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 7, characterized in that: The filter cloth self-adaptive system includes filter cloth spreading, cleaning, air drying, cloth correction and detection functions.

9. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 1, characterized in that: In step (2), the water content of the sludge is reduced to below 60% by filter pressing.

10. The sludge treatment method combining biological treatment with high-pressure thin-layer filter press according to claim 1, characterized in that: The sludge is subjected to biological drying by utilizing the action of the remaining microorganisms after the filter pressing or is subjected to thermal drying by utilizing the waste heat of the cement kiln, thereby converting the sludge into an alternative fuel for the cement kiln.

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