Treatment method and system for enhancing efficiency of biochemical system and realizing sludge recycling

Abstract

The invention relates to a treatment method and system for enhancing the efficiency of a biochemical system and realizing sludge recycling, and the treatment method comprises the following steps: separating light sludge, heavy sludge and sand from activated sludge through a cyclone separator; wherein the light sludge is sequentially subjected to mechanical deep dehydration and low-temperature drying treatment, so that the water content is reduced to 40% or below, and biomass fuel capable of being recycled is obtained; the heavy sludge flows back to a biochemical system for sewage treatment so as to increase the sludge concentration and improve the settling performance; and sand flows back to the pretreatment system and is discharged. According to the method and the system provided by the invention, quality-divided distribution and high-efficiency recycling of the excess sludge are realized, the treatment efficiency of a biochemical system is enhanced, the problems of low recycling quality and difficult improvement of system efficiency in traditional sludge treatment are solved, and the treatment system can be integrated into modular equipment and is convenient to popularize and apply.

Description

Technical Field

[0001] This invention relates to a treatment method and system for enhancing the efficiency of biochemical systems and realizing the resource utilization of sludge, belonging to the technical field of wastewater treatment and sludge resource utilization. Background Technology

[0002] The treatment and disposal of excess activated sludge generated by wastewater treatment plants is a major challenge facing the environmental field today. Traditional sludge treatment processes typically involve directly concentrating and dewatering all excess sludge to a moisture content of 60%–80% for off-site disposal. Subsequent disposal methods such as landfilling and incineration are costly and prone to causing secondary pollution. Existing technologies suffer from the following main problems:

[0003] 1. Homogenization of sludge properties hinders resource utilization: Excess sludge actually contains components with different properties, such as light flocculent sludge rich in organic matter, heavy granular sludge with good settling properties, and inorganic sand. Traditional processes mix these components, resulting in a dilution of the overall organic matter content and a reduction in calorific value, which is not conducive to its utilization as biomass energy.

[0004] 2. Limited improvement in the efficiency of the biological system: Heavy sludge with good settling performance and high activity in the excess sludge is directly discharged, and the system cannot enrich this part of high-quality sludge, which limits the improvement of sludge concentration in the biological reactor and the improvement of sludge settling performance.

[0005] 3. Accumulation of inorganic sand particles: Sand particles carried in wastewater will gradually accumulate in the biological system, affecting equipment operation, occupying tank volume, and causing a decrease in sludge activity.

[0006] Therefore, developing a method that can accurately separate excess sludge and "divide and divert according to different components to make the best use of resources" is of great significance for reducing treatment costs, improving system efficiency, and realizing sludge resource utilization. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the technical problems of high cost and difficulty in resource utilization of residual activated sludge in existing technologies, this invention provides a treatment method and system for enhancing the efficiency of biochemical systems and realizing sludge resource utilization.

[0009] (II) Technical Solution

[0010] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0011] In a first aspect, the present invention provides a method for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge, comprising the following steps:

[0012] S1. Cyclone Separation: The remaining activated sludge is pumped into a static cyclone separator for screening to separate light sludge, heavy sludge and sand.

[0013] S2. The separated light sludge, heavy sludge, and sand shall be treated as follows:

[0014] Lightweight sludge resource utilization: The lightweight sludge obtained in step S1 is subjected to mechanical deep dewatering and low-temperature drying treatment in sequence to reduce its moisture content to below 40%, thereby increasing the calorific value of the sludge and obtaining biomass fuel that can be utilized for resource utilization.

[0015] Heavy sludge return: The heavy sludge obtained in step S1 is returned to the biological system of wastewater treatment to enhance the treatment efficiency of the biological system;

[0016] Sand treatment: The sand separated in step S1 is returned to the sand-water separator of the pretreatment system of the sewage treatment plant. After separation, it is transported off-site for disposal together with the sand produced in the pretreatment.

[0017] In the treatment method described above, preferably, in step S1, the moisture content of the residual activated sludge is 99%~99.5%; the organic matter content of the light sludge is 60%~80%, and the density is less than 1.02 g / cm³. 3 The dry basis calorific value reaches 12~16 MJ / kg; the heavy sludge mainly has a density higher than 1.05 g / cm³. 3 The SVI (sludge volume index) is less than 80 mL / g; sand is inert inorganic particles (non-sludge) entrained in sludge.

[0018] As described above, preferably, in step S2, the mechanical deep dewatering is carried out sequentially using a screw press dewatering machine and a high-pressure belt filter press. Specifically, this includes: first, feeding the light sludge into the screw press dewatering machine for preliminary dewatering, while adding 1‰ to 5‰ of the dry light sludge mass of PAM conditioner for rapid and continuous dewatering, reducing the moisture content from over 99% to 80% to 85%; then conveying it to the high-pressure belt filter press for strong pressing dewatering, further reducing the moisture content to 70%; and finally, feeding it into a low-temperature dryer.

[0019] In the above-described treatment method, preferably, ferrous sulfate is added to the high-pressure belt filter press. The amount of ferrous sulfate is 2% to 6% of the dry light sludge mass. Before use, the ferrous sulfate is prepared into a 5% to 10% aqueous solution and then added. The pH of the sludge system is maintained at 7.0 to 8.0. If it is too acidic, a small amount of lime is added to adjust the pH value.

[0020] In the processing method described above, preferably, the pressure of the high-pressure belt filter press is 0.6~1.2 MPa, the filter belt running speed is 1~3 m / min, the cylinder tension is 0.3~0.6 MPa, and the high-pressure belt filter press uses 9~12 stages of pressing rollers to achieve filtration; the pressure of the rinsing water is 0.3~1.0 MPa.

[0021] In the processing method described above, preferably, in step S2, the mechanical deep dewatering is achieved using a plate and frame filter press, wherein the pressure of the plate and frame filter press is 0.8~1.2 MPa and the feed flow rate is 0.5~1.0 m / s. 3 / (m 2 •h); the pressing pressure is 1.6~2.5MPa, the pressing holding time is 20~40 min; the filter plate opening speed during unloading is 50~100mm / s, and the pressure of the filter cloth cleaning and rinsing water is 0.3~1.0MPa.

[0022] In the above-described treatment method, preferably, PAM and PAC or ferrous sulfate are added simultaneously during the plate and frame filter press dewatering process; wherein, the amount of PAM is 1‰ to 5‰ of the dry light sludge mass, and the amount of PAC is 2 to 10% of the dry light sludge mass.

[0023] In the above-described processing method, preferably, the drying temperature of the low-temperature drying treatment is 65~75℃, the hot air velocity is 1~3m / s, the material residence time is 3~8h, and the material layer thickness is 2~5cm.

[0024] In a preferred embodiment, the low-temperature drying process is carried out using a low-temperature dryer, which feeds sludge into columnar strips, which are then dried to form columnar biomass fuel with a diameter of 0.5-1 cm and a length of 3-5 cm.

[0025] Secondly, the present invention provides a treatment system for enhancing the efficiency of activated sludge biochemical systems and realizing sludge resource utilization, comprising a static sludge hydrocyclone separator, a mechanical deep dewatering system, and a low-temperature dryer connected in sequence by pipes and pumps; the static sludge hydrocyclone separator is provided with a heavy sludge outlet and a sand outlet, the heavy sludge outlet is connected to the sludge return pipe of the biochemical system, and the sand outlet is connected to the sand-water separator of the pretreatment system; wherein, the mechanical deep dewatering system comprises a combination of a screw press dewatering machine and a high-pressure belt filter press connected in sequence, or the mechanical deep dewatering system is a plate and frame deep dewatering machine;

[0026] The discharge port of the screw press dewatering machine is connected to the inlet of the high-pressure belt filter press, and the screw press dewatering machine and the high-pressure belt filter press are respectively equipped with a dosing device;

[0027] The plate and frame filter press dewatering machine is also equipped with a chemical dosing device;

[0028] Between the mechanical deep dewatering system and the low-temperature dryer, there is also a strip cutter that cuts light sludge into columnar strips.

[0029] (III) Beneficial Effects

[0030] The beneficial effects of this invention are:

[0031] The present invention provides a method for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge, which has the following advantages:

[0032] 1. Component separation enables differentiated processing and utilization.

[0033] This invention provides a method for enhancing the efficiency of a biochemical system and realizing sludge resource utilization. Through a static hydrocyclone separator (a physical method using centrifugal force and gravity difference, without the addition of chemicals during the separation process), it achieves the separation of light organic sludge, heavy activated sludge, and inorganic sand from excess sludge, laying the foundation for subsequent fractional treatment and resource utilization. Traditional processes treat excess sludge as a homogeneous mixture, resulting in the dilution of organic matter, a decrease in calorific value, and difficulty in resource utilization.

[0034] 2. Enhance the biochemical system to improve processing efficiency.

[0035] This invention provides a method for enhancing the efficiency of a biological system and realizing sludge resource utilization. By recirculating heavy sludge, it effectively "optimizes" the biological system, significantly increasing MLSS concentration, improving MLVSS / MLSS ratio by 10%-30%, and reducing SVI to 50mL / g-100mL / g. This improves sludge settling performance and enhances system stability and treatment efficiency. In contrast, in traditional processes, highly efficient heavy granular sludge is directly discharged, preventing the system from enriching high-quality microbial strains.

[0036] 3. Clear resource utilization path

[0037] The light sludge separated in this invention has a high organic matter content after enrichment. Through a combination of mechanical deep dewatering and low-temperature drying, it can be made into biomass fuel with a moisture content of <40% and qualified calorific value, realizing the transformation from "waste" to "resource".

[0038] 4. Remove inorganic interference

[0039] This invention provides a treatment method for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge. It effectively separates and discharges sand particles from the system, protecting downstream equipment and pipelines, and improving the operating efficiency and lifespan of the entire wastewater treatment system.

[0040] 5. Equipment integration

[0041] This invention provides a treatment method for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge. The core unit of this method (cyclone separation + mechanical deep dewatering system + drying) can be integrated into a compact, modular set of equipment, which has the advantages of small footprint, high degree of automation, and easy transportation and installation. It is particularly suitable for upgrading existing sewage treatment plants and new construction projects.

[0042] 6. Win-win situation for both economic and environmental benefits

[0043] The method provided by this invention enhances the biochemical system through component separation while significantly reducing the amount of sludge requiring dewatering and drying. Only the moisture content of the target resource-harvested light sludge needs to be reduced to below 40% to meet calorific value requirements. Although the initial investment is slightly higher, the sludge reduction effect is significant, and the resource utilization of sludge is achieved, exhibiting environmentally friendly characteristics and a superior life-cycle cost, demonstrating outstanding economic and environmental benefits. In contrast, traditional sludge treatment processes directly concentrate and dewater all remaining sludge to a moisture content of 60%~80% before off-site disposal. While the initial investment is lower, this approach poses significant environmental risks and incurs high subsequent disposal costs, making it less economically viable from a long-term, end-to-end perspective. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of a preferred method of the present invention for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge;

[0045] Figure 2 This is a schematic diagram of the process for enhancing the efficiency of the biochemical system and realizing the resource utilization of sludge in Embodiment 1 of the present invention;

[0046] Figure 3 This is a schematic diagram of the process for enhancing the efficiency of the biochemical system and realizing the resource utilization of sludge in Embodiment 1 of the present invention. Detailed Implementation

[0047] This invention provides a method for enhancing a biological system and utilizing sludge resources, the process flow diagram of which is shown below. Figure 1 As shown, the specific steps include the following:

[0048] S1. Cyclone Separation: The excess activated sludge with a moisture content of approximately 99%~99.5% is pumped into a static cyclone separator. Using centrifugal force and gravity difference, it is separated into three parts: light sludge, heavy sludge, and sand.

[0049] S2. The separated light sludge, heavy sludge, and sand shall be treated as follows:

[0050] Lightweight sludge resource utilization: Lightweight sludge (mainly composed of high-organic-matter flocculent sludge, with an organic matter content typically reaching 60%-80%, low density, poor settling performance, and a dry-basis calorific value of 12-16 MJ / kg) is sequentially fed into a mechanical deep dewatering system and a low-temperature dryer for dewatering and drying. The final product is dried sludge with a moisture content of less than 40%, high organic matter content, and a calorific value meeting the standards for self-sustaining combustion, thus enabling resource utilization.

[0051] The wastewater separated by the mechanical deep dehydration system and the low-temperature dryer is returned to the sewage treatment plant.

[0052] Heavy sludge recirculation: The heavy sludge obtained in step S1 (mainly composed of granular sludge with good settling performance and high activity, with a density higher than 1.05 g / cm³ and a sludge volume index lower than 80 mL / g) is directly recirculated to the biological system of wastewater treatment, such as A / O tank, A² / O tank, SBR reactor, etc., to enhance the treatment efficiency of the biological system. In this process, the average sludge concentration (MLSS) in the system can be increased, the MLVSS / MLSS ratio can be increased (usually by 10%-30%), the sludge settling performance can be improved, and the sludge volume index (SVI) can be reduced, thereby enhancing the pollutant removal efficiency of the biological system.

[0053] Sand treatment: The sand separated in step S1 is returned to the sand separator in the pretreatment system of the sewage treatment plant, such as a vortex grit chamber or an aerated grit chamber system; after separation, it is transported off-site for disposal together with the sand produced in the pretreatment; to avoid accumulation in the biological system.

[0054] In the method described above, preferably, in step S2, the light sludge first enters a screw press dewatering machine for preliminary dewatering, and 1‰~5‰ of the dry light sludge mass of PAM conditioner is added to achieve rapid and continuous dewatering, reducing the moisture content from over 99% to 80%~85%. Then, it enters a high-pressure belt filter press for strong pressing dewatering, further reducing the moisture content to about 70%. Finally, it enters a low-temperature dryer, where heat pump technology is used to dry the sludge at a low temperature (65~75℃), ultimately obtaining biomass fuel with a moisture content of 40%, which can be packaged and transported for use as auxiliary fuel, such as fuel for heating boilers.

[0055] It should be noted that the "mass of dry light sludge" mentioned in this invention refers to the total mass of the dry sludge product obtained after the light sludge has been dried. Some of the added agents are generally added according to the mass of the dry light sludge.

[0056] Preferably, in the method described above, ferrous sulfate is added to the high-pressure belt filter press. The amount of ferrous sulfate is 2% to 6% of the dry light sludge mass. Before use, a 5% to 10% aqueous solution is prepared and added. The pH of the sludge system should be maintained at 7.0 to 8.0. If it is too acidic, a small amount of lime can be added to adjust the pH value.

[0057] In the method described above, preferably, the operating parameters of the high-pressure belt filter press are: pressure of 0.6~1.2MPa, filter belt running speed of 1~3 m / min, cylinder tension of 0.3~0.6MPa, and 9~12 grade pressing rollers; the pressure of the rinsing water is 0.3~1.0MPa.

[0058] Preferably, in step S2, the mechanical deep dewatering system described above is a plate and frame filter press, wherein the pressure of the plate and frame filter press is 0.8~1.2MPa and the feed flow rate is 0.5~1.0 m / s. 3 / (m 2 •h); the pressing pressure is 1.6~2.5MPa, the pressing holding time is 20~40 min; the filter plate opening speed during unloading is 50~100mm / s, and the pressure of the filter cloth cleaning and rinsing water is 0.3~1.0MPa.

[0059] In the method described above, preferably, the drying temperature of the low-temperature dryer is 65~75℃, the hot air velocity is 1.5~3m / s, the material residence time is 4~8h, and the material layer thickness is 2~5cm.

[0060] Extensive experimental research has found that adding ferrous sulfate during high-pressure belt filter press dewatering addresses the issues of high viscosity, high filter cake moisture content, and easy adhesion to the filter belt, while also enhancing pollutant removal. Because the sludge after dewatering by the screw press has a moisture content of 80%–85%, it is still mainly composed of organic slime with a loose and tough floc structure, making it easily deformed under high pressure, hindering water removal and causing the filter cake to adhere to the filter belt surface, resulting in unloading difficulties. Ferrous sulfate dissolves in water and ionizes to release Fe. 2+In a weakly alkaline environment, ferrous hydroxide colloids are generated in sludge, which are further oxidized into ferric hydroxide flocs. These inorganic flocs can act as a rigid framework, embedding themselves in the pores of organic sludge flocs and supporting a stable porous structure. During high-pressure pressing, water can quickly pass through the pores instead of being locked in by the compressed flocs, thereby stabilizing the sludge moisture content from 80%~85% to about 70%, while reducing filter cake stickiness and improving pressing and dewatering efficiency. Because small-molecule organic matter and colloids in light sludge easily clog the filter belt pores of belt filter presses, the filtration speed decreases and the pressing cycle is prolonged. Ferric hydroxide flocs have strong adsorption properties and can adsorb fine colloidal particles in sludge, forming larger flocs and preventing small particles from penetrating into the filter belt pores; at the same time, the filter cake formed by rigid flocs has higher porosity and lower filtrate permeability resistance, which can shorten the pressing time, reduce the frequency of filter belt cleaning, and reduce equipment operating energy consumption. In addition, the addition of ferrous sulfate during the high-pressure belt filter press stage can further adsorb phosphates and heavy metal ions (such as Pb) in the sludge. 2+ Cd 2+ ) and some chromatic substances: Fe 2+ It reacts with phosphate to form ferric phosphate precipitate, reducing the risk of phosphorus leaching from the sludge; ferric hydroxide colloid fixes heavy metals through surface complexation and adsorption, reducing secondary pollution of heavy metals during subsequent drying and combustion; ultimately improving the cleanliness of dried sludge as biomass fuel and enhancing the resource value of sludge.

[0061] The dosage of ferrous sulfate is 2% to 6% of the dry light sludge mass (i.e., 20 to 60 kg of ferrous sulfate per ton of dry light sludge). To avoid clumping of the dry powder and improve mixing efficiency with the sludge, the ferrous sulfate should first be prepared into a 5% to 10% aqueous solution before addition. It is also important to maintain the pH of the light sludge system at 7.0 to 8.0. If it is too acidic, a small amount of lime can be added to adjust the pH, ensuring complete hydrolysis to generate ferric hydroxide flocs.

[0062] The optimal pressure for a high-pressure belt filter press is 0.6~1.2 MPa, which is the high-pressure pressing pressure and effectively reduces moisture content. Excessive belt speed will lead to high moisture content; a speed of 1~3 m / min is preferred. Cylinder tension ensures the filter belt exerts sufficient pressure on the sludge to prevent slippage; a pressure of 0.3~0.6 MPa is preferred. The number and arrangement of the pressing rollers: 9~12 stages of pressing rollers are used to prevent sludge from being squeezed out of the filter belt under instantaneous pressure. The flushing water pressure is 0.3~1.0 MPa; either clean water or recycled water can be used to clean the filter belt pores and maintain filtration performance.

[0063] When using a plate and frame filter press as the mechanical deep dewatering system, research has found that the pressure during the feeding stage needs to be higher than 0.8 MPa, relying on pressure to push the sludge filtrate through the filter cloth; however, the pressure should not exceed 1.2 MPa. Pressures above 1.2 MPa can easily cause floc breakage, leading to filtration failure or filter cloth blockage. Therefore, the preferred pressure is 0.8~1.2 MPa. Excessive feed velocity can result in uneven sludge distribution in the filter chamber, leading to excessively thick filter cakes in some areas; excessively slow velocity prolongs the feeding time and reduces treatment efficiency. Therefore, the preferred feed velocity is 0.5~1.0 m. 3 / (m 2 The flow rate range of h) ensures uniform filling of the filter chamber while maintaining a stable filtrate throughput. During the pressing stage, diaphragm pressing (rubber diaphragm filter plates) is used. The preferred pressing pressure is 1.6~2.5 MPa, which effectively squeezes out water without damaging the filter cake structure and causing cracking. The pressing holding time must ensure that the pressure is fully transmitted to the interior of the filter cake, allowing capillary water to gradually drain. Insufficient holding time results in a high moisture content, and after 40 minutes, the dewatering efficiency decreases marginally, increasing energy consumption. Therefore, the preferred pressing holding time is 20~40 minutes. If the filter plate opening speed during the unloading stage is too low, such as below 50 mm / s, the mud cake will not completely detach due to inertia, and the filter cloth will stick. If the speed is too high, such as above 100 mm / s, the filter plate is easily damaged by collision, or the mud cake will break and scatter. Therefore, the preferred filter plate opening speed is 50~100 mm / s. High-pressure rinsing with flushing water can remove residual sludge from the filter cloth pores and restore the filter cloth's permeability. If the pressure is too high, it will damage the filter cloth fibers, and if it is too low, the cleaning will not be thorough, affecting the dewatering efficiency of the next batch. Therefore, the preferred flushing water pressure is 0.3~1.0 MPa.

[0064] Preferably, PAC and PAM are added for synergistic treatment during the plate and frame filter press deep dewatering process. Since the light sludge colloidal particles are negatively charged, PAC hydrolyzes in water to generate polynuclear aluminum hydroxyl complex ions, which can quickly neutralize the negative charge of the sludge colloids, disrupting their stability and promoting the aggregation of tiny particles into loosely structured primary inorganic flocs. Simultaneously, the aluminum salt flocs formed by PAC can serve as the core framework for flocculation, providing support for the subsequent adsorption and cross-linking of PAM, solving the problem of low floc strength and easy breakage under high pressure when PAM is added alone. PAM (cationic type) has a large number of positively charged groups on its molecular chain, which can adsorb onto the surface of the primary flocs formed by PAC. Through the bridging effect of the long molecular chains, the dispersed primary flocs are cross-linked into dense, high-strength large flocs. These composite flocs have high porosity and strong compressive strength. Under the high pressure of the plate and frame filter press, water can quickly pass through the filter cloth and be discharged, avoiding water retention due to floc compression and ensuring that the moisture content of the sludge cake is stably reduced to about 65%. Compared to adding PAM alone, the combined addition of PAC and PAM has a synergistic effect, increasing floc strength by more than 30%, improving filter cake permeability by 20% to 40%, and shortening the feeding and pressing time of plate and frame filter presses. It also reduces the amount of PAM used (saving 10% to 20% compared to adding it alone), lowering reagent costs. Simultaneously, it reduces the risk of fine flocs clogging the filter cloth, extends the filter cloth cleaning cycle, and lowers equipment operation and maintenance costs. The dosage of PAM is 1‰ to 5‰ of the dry light sludge mass (i.e., 1 to 5 kg of PAM per ton of dry light sludge); the dosage of PAC is 2% to 10% of the dry light sludge mass (i.e., 20 to 100 kg of PAC per ton of dry light sludge). To avoid dry powder clumping and improve mixing efficiency with sludge, PAM should first be prepared as a 0.1% aqueous solution, and PAC as a 5% to 10% aqueous solution before addition.

[0065] Low-temperature drying using heat pump technology avoids organic matter decomposition and preserves the calorific value of the sludge. The optimal drying temperature for the low-temperature dryer is 65~75℃, ensuring drying efficiency while preventing sludge spontaneous combustion or organic matter carbonization. The optimal hot air velocity is 1~3m / s to ensure uniform temperature within the drying chamber and avoid localized overheating. The optimal material residence time is 3~8 hours; the specific time can be adjusted according to the sludge feed rate and target moisture content. Sufficient residence time is required when the moisture content decreases from 70% to 40%. If the material layer thickness is too thick, it will lead to insufficient internal drying; if it is too thin, energy consumption will be too high. Therefore, the optimal material layer thickness is 2~5 cm.

[0066] Preferably, the low-temperature drying feed uses a strip cutter to cut the sludge into columnar strips, which, after drying, form columnar biomass fuel with a diameter of 0.5~1cm and a length of 3~5cm.

[0067] This invention provides an enhanced biochemical treatment system for excess sludge, comprising a static sludge hydrocyclone separator, a mechanical deep dewatering system, and a low-temperature dryer connected in sequence by pipes and pumps; the static sludge hydrocyclone separator is further provided with a heavy sludge outlet and a sand outlet, wherein the heavy sludge outlet is connected to the sludge return pipe of the biochemical system; and the sand outlet is connected to the sand-water separator of the pretreatment system.

[0068] Furthermore, the mechanical deep dewatering system is a combined equipment of a screw press dewatering machine and a high-pressure belt filter press, wherein the discharge port of the screw press dewatering machine is connected to the inlet of the high-pressure belt filter press, and the screw press dewatering machine and the high-pressure belt filter press are respectively equipped with a dosing device;

[0069] Alternatively, the mechanical deep dewatering system may be a plate and frame filter press; the plate and frame filter press is also equipped with a chemical dosing device.

[0070] Furthermore, a strip cutter is provided between the mechanical deep dewatering system and the low-temperature dryer to cut the light sludge into columnar strips.

[0071] These can be integrated into modular equipment, making them easy to promote and apply.

[0072] To better explain and facilitate understanding of the present invention, a detailed description of the invention is provided below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art, and the reagents used in the present invention are all commercially available products.

[0073] Example 1

[0074] This embodiment provides a treatment method for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge, the process diagram of which is shown below. Figure 2 As shown, it includes the following steps:

[0075] S1. Cyclone Separation: The residual sludge with a moisture content of 99%~99.5% discharged from the secondary sedimentation tank of the wastewater treatment plant is transported by a feed pump to a static sludge cyclone separator; the inlet pressure is controlled at 0.1~0.4MPa, and the sludge is classified within the cyclone separator.

[0076] The sludge discharged from the top overflow outlet is the lightest sludge, which is mainly composed of loose flocs with an organic matter content of 60% to 80% and a density of less than 1.02 g / cm³. It has poor settling performance and a dry basis calorific value of 12 to 16 MJ / kg, and then enters the subsequent resource recovery treatment line.

[0077] The sludge discharged from the outlet on the side of the middle section is of moderate density. The sludge is mainly composed of dense particles with a density higher than 1.05 g / cm³. It is directly transported back to the anoxic or aerobic tank of the biological system through pipelines and return pumps.

[0078] The densest sand particles are discharged from the bottom outlet and are directed to the sand-water separator in the pretreatment section.

[0079] S2. The separated light sludge, heavy sludge, and sand shall be treated as follows:

[0080] Lightweight sludge resource utilization: The lightweight sludge first enters a screw press for preliminary dewatering, and PAM conditioner is added to achieve rapid and continuous dewatering, reducing the moisture content from over 99% to 80%~85%. Then, it enters a high-pressure belt filter press for strong pressing dewatering. A 5%~10% ferrous sulfate aqueous solution is added to the high-pressure belt filter press, and the pH value of the lightweight sludge in the high-pressure belt filter press is maintained at 7.0~8.0. The preferred operating parameters of the high-pressure belt filter press are: pressure 0.6~1.2 MPa, filter belt running speed 1~3 m / min, cylinder tension 0.3~0.6 MPa, 9~12 grade press rollers, and washing water pressure 0.3~1.0 MPa.

[0081] The moisture content is further reduced to about 70% using a high-pressure belt filter press. Finally, the sludge enters a low-temperature dryer, where heat pump technology is used to dry it at a low temperature of 65~75℃. The hot air velocity is 1~3 m / s, the material residence time is 3~8 hours, and the material layer thickness is 2~5 cm. The final product is biomass fuel with a moisture content of 40%, which can be packaged and transported for use as auxiliary fuel.

[0082] Heavy sludge return: The heavy sludge obtained in step S1 is returned to the biological system of wastewater treatment to enhance the treatment efficiency of the biological system;

[0083] Sand treatment: The sand separated in step S1 is returned to the sand-water separator of the pretreatment system of the sewage treatment plant. After separation, it is transported off-site for disposal together with the sand produced in the pretreatment.

[0084] The core equipment in this method includes a static sludge hydrocyclone separator, a screw press dewatering machine, a high-pressure belt filter press, and a low-temperature dryer. These components can be fixed on a frame and equipped with corresponding pipelines, pumps, valves, and control systems to form an integrated set of equipment for deep sludge treatment and resource utilization. The combination of the screw press dewatering machine and the high-pressure belt filter press is suitable for scenarios with large processing volumes and high requirements for continuous operation, and has the advantages of high automation, small footprint, and controllable operating costs.

[0085] Example 2

[0086] This embodiment provides a treatment method for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge, which includes the following steps:

[0087] S1. Cyclone Separation: 200 t / d of residual sludge with a moisture content of 99%, a dry basis weight of 2 t / d, a dry basis calorific value of 10 MJ / kg, and an organic matter content of 50%, discharged from the secondary sedimentation tank of the wastewater treatment plant, is pumped to a static sludge cyclone separator. The inlet pressure is controlled at 0.1-0.4 MPa, and the sludge is classified within the cyclone separator.

[0088] The top overflow outlet discharges 177 t / d of lightweight sludge with a moisture content of 99.3% and the lowest density, with an organic matter content of up to 60% and a dry basis calorific value of up to 12 MJ / kg, which enters the subsequent resource recovery treatment line.

[0089] The outlet on the middle side discharges 15 t / d of heavy sludge with a moderate density and a water content of 98%; it is directly transported back to the anoxic or aerobic tank of the biological system through pipelines and return pumps.

[0090] The sand discharged from the bottom outlet, which is 8t / d of the densest sand with a moisture content of 95%, is led to the sand-water separator in the pretreatment section.

[0091] S2. The separated light sludge, heavy sludge, and sand shall be treated as follows:

[0092] Lightweight sludge resource utilization: The lightweight sludge first enters a screw press for preliminary dewatering, with 6.5 t / d of a 1‰ PAM aqueous solution conditioner added (the dry powder dosage is 5‰ of the dry lightweight sludge mass) to achieve rapid and continuous dewatering, reducing the moisture content from 99.3% to 80%, generating 170.5 t / d of wastewater. Then, it enters a high-pressure belt filter press for intensive pressing dewatering, with 0.78 t / d of a 10% FeSO4 aqueous solution added (the dry powder dosage is 6% of the dry lightweight sludge mass). The preferred operating parameters for the high-pressure belt filter press are: pressure 0.6~1.2 MPa, filter belt speed 1~3 m / min, cylinder tension 0.3~0.6 MPa, using 12-stage press rollers, and flushing water pressure 0.3~1.0 MPa. All of these parameters are adjustable during operation.

[0093] The sludge moisture content is further reduced to 70% using a high-pressure belt filter press. The filtration process requires 128 t / d of flushing water, producing 4.3 t / d of sludge with a 70% moisture content and 130.2 t / d of wastewater. The sludge then enters a low-temperature dryer, where heat pump technology dries it at 65-75℃. The hot air velocity is 1-3 m / s, the material residence time is 3-8 h, and the material layer thickness is 2-5 cm; all parameters are adjustable during operation. The final product is 2.2 t / d of pellet biomass fuel with a moisture content below 40% and a calorific value greater than 1500 kcal / kg, which can be packaged and transported for auxiliary fuel use. The drying process generates 2.1 t / d of wastewater.

[0094] Heavy sludge return: The heavy sludge obtained in step S1 is returned to the biological system of wastewater treatment. After long-term optimized operation, the MLVSS / MLSS of the biological system can be increased by 10%~30% and the SVI can be reduced to 50mL / g~100mL / g, thereby enhancing the treatment efficiency of the biological system.

[0095] Sand treatment: The sand separated in step S1 is returned to the sand-water separator of the pretreatment system of the sewage treatment plant. After separation, 1 t / d of sand with a moisture content of 60% is produced and transported off-site for disposal together with the sand produced in the pretreatment.

[0096] The core equipment in this method includes a sludge static hydrocyclone separator, a screw press dewatering machine, a high-pressure belt filter press, and a low-temperature dryer. These can be fixed on a frame and equipped with corresponding pipelines, pumps, valves, and control systems to form an integrated set of equipment for deep sludge treatment and resource utilization.

[0097] Furthermore, a strip cutter is installed between the mechanical deep dewatering system and the low-temperature dryer to cut the light sludge into columnar strips. After drying, the sludge is cut into columnar strips with a diameter of 0.5~1cm and a length of 3~5cm to form columnar biomass fuel.

[0098] After being classified by a static cyclone separator, the remaining sludge is divided into light sludge that can be further processed and recycled, heavy sludge that can be returned to the biological treatment system to enhance efficiency, and sand. This strengthens the biological treatment system and reduces the amount of sludge to be treated and disposed of, while also allowing for resource utilization as biomass fuel. The light sludge is treated using a combination of a screw press dewatering machine and a high-pressure belt filter press, which has the advantages of continuous operation, high degree of automation, and small footprint. The wastewater generated can be returned to the wastewater treatment plant for pre-treatment and discharge to meet standards.

[0099] Example 3

[0100] This embodiment provides a treatment method for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge, the process diagram of which is shown below. Figure 3 As shown, it includes the following steps:

[0101] S1. Cyclone Separation: The residual sludge with a moisture content of 99%~99.5% discharged from the secondary sedimentation tank of the wastewater treatment plant is transported by a feed pump to a static sludge cyclone separator; the inlet pressure is controlled at 0.1~0.4MPa, and the sludge is classified within the cyclone separator.

[0102] The sludge discharged from the top overflow outlet is the lightest type, consisting mainly of loose flocs with an organic matter content of 60%–80% and a density of less than 1.02 g / cm³. 3 It has poor settling performance, and its dry basis calorific value can reach 12~16 MJ / kg, so it enters the subsequent resource utilization process.

[0103] The sludge discharged from the outlet on the central side is a moderately dense heavy sludge, which is mainly composed of dense particles with a density higher than 1.05 g / cm³. 3 It is directly transported back to the anoxic or aerobic tank of the biochemical system via pipelines and return pumps.

[0104] The densest sand particles are discharged from the bottom outlet and are directed to the sand-water separator in the pretreatment section.

[0105] S2. The separated light sludge, heavy sludge, and sand shall be treated as follows:

[0106] Light sludge resource utilization: The light sludge first enters the plate and frame filter press for deep dewatering, and at the same time, 1‰~5‰ of the dry light sludge mass of PAM (polyacrylamide) and 2~10% of PAC (polyaluminum chloride) are added.

[0107] The feed pressure of the plate and frame filter press is 0.8~1.2MPa, the feed flow rate is 0.5~1.0 m³ / (m²·h); the pressing pressure is 1.6~2.5MPa, the pressing and holding time is 20~40min; the filter plate opening speed during unloading is 50~100mm / s, and the pressure of the filter cloth washing water is 0.3~1.0MPa.

[0108] The moisture content is reduced to about 65%, resulting in high dehydration efficiency and low moisture content in the mud cake.

[0109] The sludge then enters a low-temperature dryer, where heat pump technology is used to dry it at a low temperature of 65~75℃. The hot air velocity is 1~3m / s, the material residence time is 3~8h, and the material layer thickness is 2~5cm. Finally, biomass fuel with a moisture content of 40% is obtained, which can be packaged and transported for use as auxiliary fuel.

[0110] Heavy sludge return: The heavy sludge obtained in step S1 is returned to the biological system of wastewater treatment to enhance the treatment efficiency of the biological system;

[0111] Sand treatment: The sand separated in step S1 is returned to the sand-water separator of the pretreatment system of the sewage treatment plant. After separation, it is transported off-site for disposal together with the sand produced in the pretreatment.

[0112] The core equipment in this process—a static cyclone separator for sludge, a plate and frame dewatering machine, and a low-temperature dryer—can be fixed on a frame and equipped with corresponding pipelines, pumps, valves, and control systems to form an integrated sludge deep treatment and resource utilization system. The plate and frame dewatering machine has advantages such as simple equipment, low moisture content in the dewatered cake, good shaping, ease of subsequent drying, and low dewatering cost. However, it requires a slightly larger footprint and operates non-continuously.

[0113] Example 4

[0114] This embodiment provides a treatment method for enhancing the efficiency of a biochemical system and realizing the resource utilization of sludge, including the following steps and parameters:

[0115] S1. Cyclone Separation: 200 t / d of residual sludge with a moisture content of 99%, a dry basis weight of 2 t / d, a dry basis calorific value of 10 MJ / kg, and an organic matter content of 50%, discharged from the secondary sedimentation tank of the wastewater treatment plant, is pumped to a static sludge cyclone separator. The inlet pressure is controlled at 0.1~0.4 MPa, and the sludge is classified within the cyclone separator.

[0116] The top overflow outlet discharges 177 t / d of lightweight sludge with a moisture content of 99.3% and the lowest density, with an organic matter content of up to 60% and a dry basis calorific value of up to 12 MJ / kg, which enters the subsequent resource recovery treatment line.

[0117] The outlet on the middle side discharges 15 t / d of heavy sludge with a moderate density and a water content of 98%; it is directly transported back to the anoxic or aerobic tank of the biological system through pipelines and return pumps.

[0118] The sand discharged from the bottom outlet, which is 8t / d of the densest sand with a moisture content of 95%, is led to the sand-water separator in the pretreatment section.

[0119] S2. The separated light sludge, heavy sludge, and sand shall be treated as follows:

[0120] Lightweight sludge resource utilization: The lightweight sludge first enters a plate and frame filter press for deep dewatering. A 1‰ PAM aqueous solution (6.5 t / d) conditioner is added (dry powder dosage is 5‰ of the dry lightweight sludge mass), and a 10% PAC aqueous solution (1.3 t / d) (dry powder dosage is 10% of the dry lightweight sludge mass) is added. The feed pressure of the plate and frame filter press is 0.8~1.2 MPa, and the feed flow rate is 0.5~1.0 m / s. 3 / (m 2 •h); the pressing pressure is 1.6~2.5MPa, the pressing holding time is 20~40min; the filter plate opening speed during unloading is 50~100 mm / s, and the pressure of the filter cloth cleaning and rinsing water is 0.3~1.0 MPa. All of the above parameters are adjustable during operation.

[0121] The sludge moisture content is reduced to 65% using a plate and frame filter press. The filtration process requires 10 t / d of flushing water, producing 3.7 t / d of sludge with a 65% moisture content and 183.3 t / d of wastewater. The sludge then enters a low-temperature dryer, where heat pump technology is used to dry it at a low temperature of 65-75℃. The hot air velocity is 1-3 m / s, the material residence time is 3-8 h, and the material layer thickness is 2-5 cm; all parameters are adjustable during operation. The final product is 2.2 t / d of pellet biomass fuel with a moisture content below 40% and a calorific value greater than 1500 kcal / kg, which can be packaged and transported for use as auxiliary fuel. The drying process generates 1.5 t / d of wastewater.

[0122] Heavy sludge return: The heavy sludge obtained in step S1 is returned to the biological system of wastewater treatment. After long-term optimized operation, the MLVSS / MLSS of the biological system can be increased by 10%-30% and the SVI can be reduced to 50mL / g-100mL / g, thereby enhancing the treatment efficiency of the biological system.

[0123] Sand treatment: The sand separated in step S1 is returned to the sand-water separator of the pretreatment system of the sewage treatment plant. After separation, 1 t / d of sand with a moisture content of 60% is produced and transported off-site for disposal together with the sand produced in the pretreatment.

[0124] The core equipment in this process—the static sludge hydrocyclone separator, the plate and frame deep dewatering machine, and the low-temperature dryer—can be fixed on a frame and equipped with corresponding pipelines, pumps, valves, and control systems to form an integrated sludge deep treatment and resource utilization system. After classification by the static sludge hydrocyclone separator, the remaining sludge is divided into light sludge that can be further processed and utilized for resource recovery, heavy sludge that is returned to the biological treatment system to enhance efficiency, and sand. This strengthens the biological treatment system while reducing the amount of sludge to be treated and disposed of, and the sludge can be utilized as biomass fuel. The plate and frame deep dewatering machine used for light sludge has the advantages of simple equipment, low moisture content in the dewatered cake, good shaping, easy subsequent drying, and low dewatering cost, but it requires a slightly larger footprint and operates non-continuously. The wastewater generated can be returned to the wastewater treatment plant for pre-treatment to meet discharge standards.

[0125] Comparative Example 1

[0126] This comparative example provides a method for the resource utilization of excess sludge, including the following steps:

[0127] S1. Cyclone Separation: 200 t / d of residual sludge with a moisture content of 99%, a dry basis weight of 2 t / d, a dry basis calorific value of 10 MJ / kg, and an organic matter content of 50%, discharged from the secondary sedimentation tank of the wastewater treatment plant, is pumped to a static sludge cyclone separator. The inlet pressure is controlled at 0.1~0.4 MPa, and the sludge is classified within the cyclone separator.

[0128] The top overflow outlet discharges 177 t / d of lightweight sludge with a moisture content of 99.3% and the lowest density, with an organic matter content of up to 60% and a dry basis calorific value of up to 12 MJ / kg, which then enters the subsequent dewatering treatment line.

[0129] The outlet on the middle side discharges 15 t / d of heavy sludge with a moderate density and a water content of 98%; it is directly transported back to the anoxic or aerobic tank of the biological system through pipelines and return pumps.

[0130] The sand discharged from the bottom outlet, which is 8t / d of the densest sand with a moisture content of 95%, is led to the sand-water separator in the pretreatment section.

[0131] S2. The separated light sludge, heavy sludge, and sand shall be treated as follows:

[0132] Light sludge dewatering: The light sludge first enters a screw press dewatering machine for preliminary dewatering, and 6.5 t / d of 1‰ PAM aqueous solution conditioner is added (the dry powder dosage is 5‰ of the dry light sludge mass) to achieve rapid and continuous dewatering, reducing the moisture content from 99.3% to 80%, generating 170.5 t / d of wastewater. Then, it enters a high-pressure belt filter press for strong pressing dewatering, and 0.78 t / d of 10% FeSO4 aqueous solution is added in the high-pressure belt filter press (the dry powder dosage is 6% of the dry light sludge mass). The preferred operating parameters of the high-pressure belt filter press are: pressure 0.6~1.2 MPa, filter belt running speed 1~3 m / min, cylinder tension 0.3~0.6 MPa, 12-stage pressing rollers, and rinsing water pressure 0.3~1.0 MPa. All of the above parameters are adjustable during operation.

[0133] The sludge moisture content is further reduced to 70% by a high-pressure belt filter press. The filtration process requires 128 t / d of flushing water, produces 4.3 t / d of sludge with a moisture content of 70% (calorific value 310 kcar / kg), and generates 130.2 t / d of wastewater.

[0134] Heavy sludge return: The heavy sludge obtained in step S1 is returned to the biological system of wastewater treatment. After long-term optimized operation, the MLVSS / MLSS of the biological system can be increased by 10%-30% and the SVI can be reduced to 50mL / g-100mL / g, thereby enhancing the treatment efficiency of the biological system.

[0135] Sand treatment: The sand separated in step S1 is returned to the sand-water separator of the pretreatment system of the sewage treatment plant. After separation, 1 t / d of sand with a moisture content of 60% is produced and transported off-site for disposal together with the sand produced in the pretreatment.

[0136] The core equipment in this method includes a static sludge hydrocyclone separator, a screw press dewatering machine, and a high-pressure belt filter press. These can be fixed on a frame and equipped with corresponding pipelines, pumps, valves, and control systems to form an integrated set of equipment for deep sludge treatment. After classification by the static sludge hydrocyclone separator, the remaining sludge is divided into light sludge that can be further dewatered, heavy sludge that is returned to the biological treatment system to enhance efficiency, and sand. This strengthens the biological treatment system on the one hand and reduces the amount of sludge to be treated and disposed of on the other. However, the sludge has a high water content and low calorific value, making it unsuitable for resource utilization.

[0137] Comparative Example 2

[0138] This comparative example provides a method for the resource utilization of excess sludge, including the following steps:

[0139] S1. Cyclone Separation: 200 t / d of residual sludge with a moisture content of 99%, a dry basis weight of 2 t / d, a dry basis calorific value of 10 MJ / kg, and an organic matter content of 50%, discharged from the secondary sedimentation tank of the wastewater treatment plant, is pumped to a static sludge cyclone separator. The inlet pressure is controlled at 0.1-0.4 MPa, and the sludge is classified within the cyclone separator.

[0140] The top overflow outlet discharges 177 t / d of lightweight sludge with a moisture content of 99.3% and the lowest density, with an organic matter content of up to 60% and a dry basis calorific value of up to 12 MJ / kg, which then enters the subsequent dewatering treatment line.

[0141] The outlet on the middle side discharges 15 t / d of heavy sludge with a moderate density and a water content of 98%; it is directly transported back to the anoxic or aerobic tank of the biological system through pipelines and return pumps.

[0142] The sand discharged from the bottom outlet, which is 8t / d of the densest sand with a moisture content of 95%, is led to the sand-water separator in the pretreatment section.

[0143] S2. The separated light sludge, heavy sludge, and sand shall be treated as follows:

[0144] Light sludge dewatering: The light sludge first enters a plate and frame filter press for deep dewatering. 6.5 t / d of a 1‰ PAM aqueous solution conditioner (dry powder dosage is 5‰ of the dry light sludge mass) and 1.3 t / d of a 10% PAC aqueous solution (dry powder dosage is 10% of the dry light sludge mass) are added. The feed pressure of the plate and frame filter press is 0.8~1.2 MPa, and the feed flow rate is 0.5~1.0 m³ / (m²·h). The pressing pressure is 1.6~2.5 MPa, and the pressing holding time is 20~40 min. The filter plate opening speed during unloading is 50~100 mm / s, and the pressure of the filter cloth washing water is 0.3~1.0 MPa. All of the above parameters are adjustable during operation.

[0145] The sludge moisture content is reduced to 65% by plate and frame filter press dewatering machine. The rinsing water required during the filter press process is 10t / d, the amount of sludge with 65% moisture content is 3.7t / d (calorific value 510kcar / kg) and the amount of wastewater generated is 183.3t / d.

[0146] Heavy sludge return: The heavy sludge obtained in step S1 is returned to the biological system of wastewater treatment. After long-term optimized operation, the MLVSS / MLSS of the biological system can be increased by 10%-30% and the SVI can be reduced to 50mL / g-100mL / g, thereby enhancing the treatment efficiency of the biological system.

[0147] Sand treatment: The sand separated in step S1 is returned to the sand-water separator of the pretreatment system of the sewage treatment plant. After separation, 1 t / d of sand with a moisture content of 60% is produced and transported off-site for disposal together with the sand produced in the pretreatment.

[0148] The core equipment in this method includes a static sludge hydrocyclone separator and a plate and frame dewatering machine, which can be fixed on a frame and equipped with corresponding pipelines, pumps, valves, and control systems to form an integrated set of equipment for deep sludge treatment. After classification by the static sludge hydrocyclone separator, the remaining sludge is divided into light sludge that can be further dewatered, heavy sludge that is returned to the biological treatment system to enhance efficiency, and sand. This strengthens the biological treatment system on the one hand and reduces the amount of sludge to be treated and disposed of on the other. However, the sludge has a high water content and low calorific value, making it unsuitable for resource utilization.

[0149] Comparative Example 3

[0150] This comparative example provides a method for the resource utilization of excess sludge, including the following steps:

[0151] 200 t / d of residual sludge with a moisture content of 99%, a dry basis weight of 2 t / d, a dry basis calorific value of 10 MJ / kg, and an organic matter content of 50%, discharged from the secondary sedimentation tank of the wastewater treatment plant, is pumped to a screw press for preliminary dewatering. 10 t / d of a 1‰ PAM aqueous solution (dry powder dosage is 5‰ of the dry light sludge mass) is added as a conditioner to achieve rapid and continuous dewatering, reducing the moisture content from 99.3% to 80%, generating 190 t / d of wastewater. This wastewater then enters a high-pressure belt filter press for intensive dewatering. 1.2 t / d of a 10% FeSO4 aqueous solution (dry powder dosage is 6% of the dry light sludge mass) is added to the high-pressure belt filter press. The optimal operating parameters for the high-pressure belt filter press are: pressure 0.6~1.2 MPa, filter belt speed 1~3 m / min, and cylinder tension 0.3~0.6 MPa. MPa, using 12-stage press rollers, the pressure of the rinsing water is 0.3~1.0 MPa, and all of the above parameters are adjustable during operation.

[0152] The sludge moisture content is further reduced to 70% using a high-pressure belt filter press. The filtration process requires 192 t / d of flushing water, producing 6.7 t / d of sludge with a 70% moisture content and 195.3 t / d of wastewater. The sludge then enters a low-temperature dryer, where heat pump technology dries it at 65-75℃. The hot air velocity is 1-3 m / s, the material residence time is 3-8 h, and the material layer thickness is 2-5 cm; all parameters are adjustable during operation. The final product is 3.3 t / d of granular sludge with a moisture content below 40% and a calorific value of 1100 kcal / kg, which can be packaged and transported for disposal. The drying process generates 3.4 t / d of wastewater.

[0153] The core equipment in this method includes a screw press dewatering machine, a high-pressure belt filter press, and a low-temperature dryer, which can be fixed on a frame and equipped with corresponding pipelines, pumps, valves, and control systems to form an integrated set of equipment for deep sludge treatment. However, it involves a large sludge treatment volume, high investment costs, and does not enhance the effectiveness of the wastewater treatment plant's biological treatment system. The resulting sludge has a low calorific value and is difficult to utilize as a resource.

[0154] Comparative Example 4

[0155] This comparative example provides a method for the resource utilization of excess sludge, including the following steps:

[0156] 200 t / d of residual sludge with a moisture content of 99% (2 t / d dry basis), calorific value of 10 MJ / kg dry basis, and organic matter content of 50% discharged from the secondary sedimentation tank of the wastewater treatment plant is pumped to a plate and frame filter press for deep dewatering. 10 t / d of a 1‰ PAM aqueous solution conditioner (dry powder dosage is 5‰ of the dry light sludge mass) and 2 t / d of a 10% PAC aqueous solution (dry powder dosage is 10% of the dry light sludge mass) are added. The feed pressure of the plate and frame filter press is 0.8~1.2 MPa, the feed flow rate is 0.5~1.0 m³ / (m²·h), the pressing pressure is 1.6~2.5 MPa, and the pressing holding time is 20~40 min. The filter plate opening speed during unloading is 50~100 mm / s, and the pressure of the filter cloth washing water is 0.3~1.0 mm / s. MPa, all of the above parameters are adjustable during operation.

[0157] The sludge moisture content is reduced to 65% using a plate and frame filter press. The filtration process requires 16 t / d of flushing water, producing 5.7 t / d of sludge with a 65% moisture content and 210.3 t / d of wastewater. The sludge then enters a low-temperature dryer, where heat pump technology is used to dry the sludge at a low temperature of 65-75℃. The hot air velocity is 1-3 m / s, the material residence time is 3-8 h, and the material layer thickness is 2-5 cm; all parameters are adjustable during operation. The final product is 3.3 t / d of granular sludge with a moisture content below 40% and a calorific value of 1100 kcal / kg, which can be packaged and transported for disposal. The drying process generates 2.4 t / d of wastewater.

[0158] The core equipment in this process—the plate and frame deep dewatering machine and the low-temperature dryer—can be fixed on a frame and equipped with corresponding pipelines, pumps, valves, and control systems to form an integrated sludge deep treatment system. However, it involves high investment costs, does not enhance the effectiveness of the wastewater treatment plant's biological treatment system, and produces sludge with low calorific value, making it difficult to utilize for resource recovery.

[0159] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art can make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A treatment method for strengthening the performance of a biochemical system and realizing sludge resource, characterized in that, It comprises the following steps: S1, cyclone separation: pump the residual activated sludge into a sludge static cyclone separator for screening, separating out light sludge, heavy sludge and sand; S2, the separated light sludge, heavy sludge and sand are treated as follows: Light sludge resource: the light sludge obtained in step S1 is sequentially subjected to mechanical deep dewatering and low-temperature drying treatment, so that the water content is reduced to below 40%, the sludge heat value is improved, and a biomass fuel that can be resourcefully utilized is obtained; Heavy sludge backflow: the heavy sludge obtained in step S1 is backflowed to the biochemical system of the sewage treatment to enhance the treatment efficiency of the biochemical system; Sand treatment: the sand separated out in step S1 is backflowed to the sand-water separator of the pretreatment system of the sewage treatment plant, and after separation, it is transported out together with the sand generated by pretreatment for disposal.

2. The treatment method of claim 1, wherein, In step S1, the water content of the residual activated sludge is 99%-99.5%; the organic matter content of the light sludge is 60%-80%, and the density is lower than 1.02 g / cm 3 ; the dry basis heat value is 12-16 MJ / kg; the heavy sludge is mainly the sludge with density higher than 1.05 g / cm 3 , and the SVI is lower than 80 mL / g; and the sand is the inert inorganic particles entrained in the sludge.

3. The treatment method of claim 1, wherein In step S2, the mechanical deep dewatering is sequentially treated by using a stacked screw dewatering machine and a high-pressure belt filter, specifically including: the light sludge is first input into the stacked screw dewatering machine for preliminary dewatering, while adding 1‰~5‰ of PAM conditioner based on the dry weight of the light sludge, for rapid and continuous dewatering, reducing the water content from more than 99% to 80%~85%; then transported to the high-pressure belt filter for strong pressing dewatering, further reducing the water content to 70%; finally, into the low-temperature drying machine.

4. The treatment method of claim 3, wherein, Ferrous sulfate is also added in the high-pressure belt filter, and the amount of ferrous sulfate is 2%~6% of the dry weight of the light sludge; before use, the ferrous sulfate is prepared into a 5%~10% aqueous solution and then added, and the pH of the sludge system is maintained at 7.0~8.0, if it is acidic, a small amount of lime is added to adjust the pH value.

5. The treatment method of claim 3, wherein The pressure of the high-pressure belt filter is 0.6~1.2MPa, the filter belt running speed is 1~3 m / min, and the cylinder tension is 0.3~0.6 MPa, and the high-pressure belt filter realizes pressure filtration by using 9~12 levels of pressing rollers; the pressure of the flushing water is 0.3~1.0MPa.

6. The treatment method of claim 1, wherein, In step S2, the mechanical deep dewatering is achieved by using a plate and frame deep dewatering machine; wherein the pressure of the plate and frame pressure filtration dewatering machine is 0.8~1.2MPa, the feeding flow rate is 0.5~1.0m 3 / (m 2 ·h); the squeezing pressure is 1.6~2.5MPa, the squeezing pressure maintaining time is 20~40min; the filter plate pulling speed during unloading is 50~100mm / s, and the pressure of the filter cloth cleaning flushing water is 0.3~1.0MPa.

7. The treatment method of claim 6, wherein, PAM and PAC are added simultaneously during the treatment of the plate and frame filter dewatering machine; wherein the amount of PAM is 1‰~5‰ of the dry weight of the light sludge, and the amount of PAC is 2~10% of the dry weight of the light sludge.

8. The treatment method of claim 1, wherein, In S2, the drying temperature of the low-temperature drying treatment is 65~75℃, the hot air speed is 1~3m / s, the material residence time is 3~8h, and the material layer thickness is 2~5cm.

9. The treatment method according to claim 1 or 8, characterized in that, The low-temperature drying treatment is carried out by using a low-temperature drying machine, and the feeding mode is: the sludge is cut into columnar strips, and after drying, columnar biomass fuel with a diameter of 0.5~1cm and a length of 3~5cm is formed.

10. A treatment system for enhancing the performance of an activated sludge enhanced biochemical system and for sludge resource utilization, characterized in that, It comprises a sludge static cyclone separator, a mechanical deep dewatering system and a low-temperature drying machine connected in sequence by pipelines and pumps; the sludge static cyclone separator is provided with a heavy sludge outlet and a sand outlet, the heavy sludge outlet is connected to a sludge backflow pipeline of a biochemical system, and the sand outlet is connected to a sand-water separator of a pretreatment system; wherein the mechanical deep dewatering system comprises a combination of stacked screw dewatering machines and high-pressure belt filters connected in sequence, or the mechanical deep dewatering system is a plate and frame deep dewatering machine; The discharge outlet of the stacked-screw dewatering machine is communicated with the feeding inlet of the high-pressure belt filter press, and the stacked-screw dewatering machine and the high-pressure belt filter press are respectively provided with a dosing device; The plate-frame filter press dewatering machine is further provided with a dosing device; A slitting machine for cutting the light sludge into columnar long strips is further arranged between the mechanical deep dewatering system and the low-temperature drying machine.

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