A method and system for treating waterworks sludge press filtrate

Abstract

The application provides a treatment method and system for tap water plant sludge pressure filtrate, and relates to the technical field of water treatment. The treatment method for the tap water plant sludge pressure filtrate comprises the following steps: performing ultrasonic treatment on the tap water plant sludge pressure filtrate; performing preliminary screening pretreatment on the tap water plant sludge pressure filtrate treated by the ultrasonic treatment, so as to remove dregs and easy sediments; introducing domestic sewage and adjusting pH; injecting mature aerobic granular sludge cultured in situ, so that the biomass is controlled within 4 g / L to 8 g / L; filtering, and performing ozone oxidation on the filtrate; and performing ultraviolet light sterilization.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and more specifically, to a method and system for treating sludge filtrate from a waterworks. Background Technology

[0002] Waterworks generate a significant amount of industrial wastewater during drinking water production, accounting for approximately 4% to 7% of the total purified water volume. This wastewater mainly includes sludge discharge from sedimentation tanks, backwash water from filters, and filtrate from sludge dewatering. During sludge dewatering, polyacrylamide filter aids are commonly added to improve dewatering efficiency, resulting in filtrate containing acrylamide monomers. This substance has significant neurotoxicity, reproductive toxicity, and potential carcinogenicity, and can damage organs such as the liver and kidneys, forcing the filtrate to be discharged as it cannot be directly reused. While existing industrial wastewater treatment systems can handle most of the wastewater, filtrate still needs to be discharged into the municipal sewer network due to safety risks, effectively shifting the treatment burden to downstream wastewater treatment plants and affecting their normal operation. This is especially problematic for waterworks located in water source protection areas, where environmental regulations strictly prohibit the discharge of filtrate, making this a critical bottleneck in achieving zero wastewater discharge. Current technologies for treating wastewater rich in polyacrylamide include physical methods, chemical oxidation methods, and microbial degradation methods. While microbial degradation can convert polyacrylamide into harmless small molecules, it lacks an efficient and practical solution tailored to the characteristics of filter press liquid from waterworks. Summary of the Invention

[0003] The present invention aims to solve the problem of direct discharge of filtrate rich in polyacrylamide.

[0004] To address the aforementioned problems, this invention provides a method and system for treating sludge filtrate from waterworks.

[0005] In a first aspect, the present invention provides a method for treating sludge filtrate from a waterworks, comprising the following steps: S1: Ultrasonic treatment of sludge filtrate from waterworks; S2: Preliminary screening and pretreatment of ultrasonically treated sludge filtrate from waterworks to remove scum and easily deposited substances; S3: Introduce domestic sewage and adjust the pH; S4: Inject mature aerobic granular sludge that has been acclimatized and cultivated in situ, so that the biomass is controlled within 4 g / L to 8 g / L; S5: Filtration, the filtrate is then subjected to ozone oxidation; S6: Ultraviolet sterilization.

[0006] Optionally, in S4, the in-situ acclimatization and cultivation method for mature aerobic granular sludge includes the following steps: S41: Prepare artificial simulated domestic sewage, wherein the chemical oxygen demand of the artificial simulated domestic sewage is 200 mg / L to 400 mg / L, and the artificial simulated domestic sewage includes ammonia nitrogen of 50 mg / L to 60 mg / L, phosphorus of 5 mg / L to 10 mg / L and polyacrylamide of 0.1 mg / L to 0.5 mg / L; S42: An intermittent operation method with each cycle lasting 3 to 6 hours is adopted, including five stages: water inflow, anoxic, aeration, sedimentation, and drainage. The ratio of the time period for anoxic to aeration is 0.2 to 0.4. The time periods for water inflow and drainage are both 3 to 8 minutes. The sedimentation time gradually decreases from 25 to 35 minutes in the first cycle to 3 to 8 minutes in the last cycle to promote the granulation of aerobic granular sludge. The aeration rate is 1 cm / s to 3 cm / s. S43: The influent is switched to a mixture of sludge dewatering liquid from the waterworks and domestic sewage. By adjusting the mixing ratio of sludge dewatering liquid from the waterworks and domestic sewage, the concentration of polyacrylamide is gradually increased from 3 mg / L to 5 mg / L to 30 mg / L to 50 mg / L. S44: The intermittent operation method with each cycle of 2 h to 8 h is adopted, which includes five stages: water inlet, anoxic, aeration, sedimentation and drainage. The ratio of the time period of anoxic to aeration is 0.2 to 0.4, the time periods of water inlet and drainage are 3 min to 8 min, and the time period of sedimentation is fixed at 3 min to 8 min; the aeration rate is 1 cm / s to 3 cm / s.

[0007] Optionally, S5 uses a ceramic membrane for filtration, with a pore size no larger than 0.5 μm; during filtration, the pure water flux of the ceramic membrane is 200 L / m³. 2 ·h300 L / m 2 •h, operating pressure is 0.1 MPa to 0.4 MPa.

[0008] Optionally, in S5, the ozone dosage for ozone oxidation is 5 mg / L to 10 mg / L.

[0009] Optionally, in S5, the ultraviolet light irradiation wavelength is 254 nm and the intensity is 10 mJ / cm. 2 Up to 100 mJ / cm 2 The irradiation time is 5 to 20 minutes.

[0010] Optionally, in S2, the frequency of the ultrasound is from 15 kHz to 50 kHz, and the power density is 0.1 W / cm². 2 Up to 1.5 W / cm 2The duration is 3 to 20 minutes to ensure that the large molecular organic matter in the sludge dewatering liquid from the waterworks is fully broken down.

[0011] Optionally, in S3, the ratio of sludge dewatering liquid from the waterworks to domestic sewage is 1:1 to 1:5. The sludge dewatering liquid from the waterworks and domestic sewage are mixed by a paddle mixer with a paddle mixer speed of 60 r / min to 120 r / min and the pH is adjusted to 6.5 to 7.5.

[0012] Secondly, the present invention provides a treatment system for sludge dewatering liquid from a waterworks, used to operate the sludge dewatering liquid treatment method described above, comprising a regulating tank, a mixing tank, a biological reactor, a microfiltration membrane tank, an ozone contact tank, and an ultraviolet treatment channel connected in sequence. The equalization tank is used to receive sludge filtrate from the waterworks and perform ultrasonic treatment and preliminary screening pretreatment. The mixing tank is used to receive the effluent from the equalization tank and mix it with domestic sewage to adjust the pH. The biological reactor is used to receive the effluent from the mixing tank and inject mature aerobic granular sludge that has been acclimatized and cultivated in situ, so that the biomass is controlled within 4 g / L to 8 g / L. Microfiltration membrane tanks are used to receive and filter the effluent from biological reactors. The ozone contact tank is used to receive the filtrate from the microfiltration membrane tank and perform ozone oxidation. The ultraviolet treatment channel is used to receive the effluent from the ozone contact tank and sterilize it with ultraviolet light.

[0013] Optionally, it also includes a thickening tank for receiving scum and easily deposited material removed from the equalization tank, and for receiving filter cake from the microfiltration membrane tank.

[0014] Optionally, it also includes backwashing equipment for backwashing the ceramic membrane of the microfiltration membrane tank, backwashing water being returned to the purified water distribution well, and effluent from the ultraviolet treatment channel being returned to the purified water distribution well.

[0015] The beneficial effects of the treatment method and system for sludge dewatering liquid from waterworks according to this invention are as follows: Ultrasonic pretreatment breaks down large molecular organic matter, and preliminary screening removes scum and easily deposited substances, laying the foundation for subsequent treatment. Introducing domestic sewage provides nutrients and adjusts the pH. Domestic sewage has a diverse composition, containing not only nutrients such as carbon, nitrogen, and phosphorus, but also minerals such as calcium, magnesium, iron, and zinc. This adjusts the composition of the dewatering liquid, making it more easily biodegradable and improving wastewater treatment efficiency. Combined with in-situ acclimated aerobic granular sludge (AGS) for efficient biodegradation of polyacrylamide, the toxicity problem of polyacrylamide in the dewatering liquid is effectively solved. Subsequent multi-stage deep treatment, including filtration, ozone oxidation, and ultraviolet sterilization, further ensures the safety of the effluent. Therefore, this method, through the organic combination of multiple steps such as ultrasonic treatment, biodegradation, membrane filtration, ozone oxidation, and ultraviolet disinfection, solves the problem of direct discharge of polyacrylamide-rich dewatering liquid from existing waterworks production wastewater and promotes the achievement of zero-discharge goals for waterworks production wastewater. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a method for treating sludge filtrate from a waterworks according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a waterworks sludge dewatering liquid treatment system according to an embodiment of the present invention; Figure 3 A schematic diagram showing the changes in characteristics of aerobic granular sludge in an effective embodiment; Figure 4 A schematic diagram illustrating the changes in chemical oxygen demand (COD) and nitrogen removal efficiency (TN) in the effective embodiment; Explanation of reference numerals in the attached figures: 1. Equalization tank; 2. Mixing tank; 3. Biological reactor; 4. Microfiltration membrane tank; 5. Ozone contact tank; 6. Ultraviolet treatment channel; 7. Thickening tank; 8. Backwashing equipment; 9. Water distribution well; 10. Waterworks. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0018] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this invention's description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "comprising" and its variations are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the description below. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0019] Among related technologies, aerobic granular sludge technology has shown potential in the treatment of high-concentration polyacrylamide wastewater, but a systematic treatment process adapted to the working conditions of waterworks has not yet been formed, making it difficult to break through the limitations of existing technologies in terms of the reuse rate of production wastewater.

[0020] To address the problems existing in the aforementioned related technologies, embodiments of the present invention provide a method and system for treating sludge dewatering liquid from waterworks.

[0021] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for treating sludge filtrate from a waterworks, comprising the following steps: S1: Ultrasonic treatment of sludge filter liquid from waterworks No. 10; S2: Preliminary screening and pretreatment of ultrasonically treated sludge filtrate from waterworks to remove scum and easily deposited substances; S3: Introduce domestic sewage and adjust the pH; S4: Inject mature aerobic granular sludge that has been acclimatized and cultivated in situ, so that the biomass is controlled within 4 g / L to 8 g / L; S5: Filtration, the filtrate is then subjected to ozone oxidation; S6: Ultraviolet sterilization.

[0022] Specifically, sludge dewatering liquid from waterworks refers to the liquid produced during the sludge dewatering process at a waterworks. It typically contains high levels of organic matter, suspended solids, and filter aids such as polyacrylamide (PAM).

[0023] Preliminary screening pretreatment refers to the removal of larger suspended solids, scum, and easily settled substances from liquids using physical methods such as grids and screens, in order to reduce the load on subsequent processing units.

[0024] Ultrasonic treatment is applied to the sludge filtrate from a waterworks. This treatment can be achieved by introducing the filtrate into a reactor equipped with an ultrasonic generator. For example, an immersion ultrasonic probe can be used directly on the liquid, or the filtrate can be treated using an external ultrasonic generator. The energy input of the ultrasound causes the large organic molecules in the liquid to break down, thereby improving their availability for subsequent biodegradation.

[0025] In this embodiment, ultrasonic pretreatment breaks down large molecular organic matter, and preliminary screening removes scum and easily deposited substances, laying the foundation for subsequent treatment. Domestic sewage is introduced to provide nutrients and adjust the pH. Domestic sewage has a diverse composition, containing not only nutrients such as carbon, nitrogen, and phosphorus, but also minerals such as calcium, magnesium, iron, and zinc. This adjusts the composition of the filtrate wastewater, making it more easily biodegradable and improving wastewater treatment efficiency. Combined with in-situ acclimated aerobic granular sludge (AGS), polyacrylamide is efficiently biodegraded, effectively solving the toxicity problem of polyacrylamide in the filtrate. Subsequent multi-stage deep treatment, including filtration, ozone oxidation, and ultraviolet sterilization, further ensures the safety of the effluent quality. Therefore, this method, through the organic combination of ultrasonic treatment, biodegradation, membrane filtration, ozone oxidation, and ultraviolet disinfection, solves the problem of direct discharge of polyacrylamide-rich filtrate from existing water plant production wastewater and promotes the achievement of zero-discharge goals for water plant production wastewater.

[0026] Optionally, in S4, the in-situ acclimatization and cultivation method for mature aerobic granular sludge includes the following steps: S41: Prepare artificial simulated domestic sewage, wherein the chemical oxygen demand (COD) of the artificial simulated domestic sewage is 200 mg / L to 400 mg / L, and the artificial simulated domestic sewage includes ammonia nitrogen of 50 mg / L to 60 mg / L, phosphorus of 5 mg / L to 10 mg / L and polyacrylamide of 0.1 mg / L to 0.5 mg / L; S42: An intermittent operation method with each cycle lasting 3 to 6 hours is adopted, including five stages: water inflow, anoxic, aeration, sedimentation, and drainage. The ratio of the time period for anoxic to aeration is 0.2 to 0.4. The time periods for water inflow and drainage are both 3 to 8 minutes. The sedimentation time gradually decreases from 25 to 35 minutes in the first cycle to 3 to 8 minutes in the last cycle to promote the granulation of aerobic granular sludge. The aeration rate is 1 cm / s to 3 cm / s. S43: The influent is switched to a mixture of sludge dewatering liquid from the waterworks and domestic sewage. By adjusting the mixing ratio of sludge dewatering liquid from the waterworks and domestic sewage, the concentration of polyacrylamide is gradually increased from 3 mg / L to 5 mg / L to 30 mg / L to 50 mg / L. S44: The intermittent operation method with each cycle of 2 h to 8 h is adopted, which includes five stages: water inlet, anoxic, aeration, sedimentation and drainage. The ratio of the time period of anoxic to aeration is 0.2 to 0.4, the time periods of water inlet and drainage are 3 min to 8 min, and the time period of sedimentation is fixed at 3 min to 8 min; the aeration rate is 1 cm / s to 3 cm / s.

[0027] Specifically, the intermittent operation method, the sequencing batch reactor (SBR), provides alternating anoxic and aerobic environments for microorganisms through periodic operation, which is beneficial to microbial growth and metabolism and promotes sludge granulation. The influent stage involves pumping simulated domestic sewage into the reactor. The anoxic stage refers to the anaerobic metabolic processes such as denitrification carried out by microorganisms under anaerobic or low-oxygen conditions, achieved, for example, by stopping or reducing aeration. The aeration stage involves introducing air into the reactor to provide sufficient oxygen for aerobic microorganisms to carry out organic matter degradation and nitrification reactions, for example, by using blowers or aeration heads. The sedimentation stage refers to stopping agitation and aeration after aeration, allowing the sludge to settle under gravity, for example, by setting it to stand. The drainage stage refers to discharging the supernatant after sedimentation, for example, by using a decanter or effluent pump. The ratio of anoxic to aeration time periods was 0.2 to 0.4, designed to balance denitrification and nitrification processes, optimize nitrogen and phosphorus removal efficiency, and provide suitable redox conditions for granular sludge formation. Influent and effluent times were both 3 to 8 minutes to ensure rapid liquid exchange, maximizing the effective reaction time within the reactor. Gradually decreasing the settling time from 25 to 35 minutes in the first cycle to 3 to 8 minutes in the last cycle was a key strategy for inducing sludge granulation. By progressively shortening the settling time, strong hydraulic selection pressure was applied to the sludge, eliminating flocculent sludge with poor settling performance and selecting and enriching fast-settling, dense granular sludge. An aeration rate of 1 to 3 cm / s provided sufficient oxygen to maintain the activity of aerobic microorganisms, while the resulting shear force helped promote microbial aggregation, inhibited the overgrowth of filamentous bacteria, and further solidified the structure of the granular sludge.

[0028] In this optional embodiment, a biological treatment system capable of efficiently degrading polyacrylamide is constructed through a phased acclimatization and granulation induction strategy. First, artificial simulated domestic wastewater containing extremely low concentrations of polyacrylamide is prepared to provide a mild start-up environment for microorganisms, using polyacrylamide as an inducer to acclimatize aerobic granular sludge. Subsequently, by strictly controlling the anoxic to aeration ratio during intermittent operation cycles and dynamically shortening the settling time, hydraulic selective pressure is used to force sludge granulation. After switching the influent to actual filter press mixed wastewater, the polyacrylamide concentration is gradually increased. This not only promotes rapid sludge granulation through the polyacrylamide coagulation and sedimentation principle but also induces the acclimatization and selection of various microbial populations with high metabolic activity and competitive advantage towards polyacrylamide within the granular sludge. These include sulfate-reducing bacteria, Pseudomonas, and fungi such as Aspergillus flavus and Aspergillus niger. This complex microbial system degrades polyacrylamide through a series of synergistic effects, including mycelial physical erosion, extracellular enzyme degradation, and intracellular metabolism. Finally, by fixing the settling time and optimizing operating parameters, the structural stability of the granular sludge was further consolidated, enabling the composite microbial system to achieve complete degradation of polyacrylamide through the synergistic effects of mycelial erosion, extracellular enzyme degradation, and intracellular metabolism. Compared with physical, chemical, and other biological methods, this method has low operating costs, high metabolic activity, and thorough degradation products, effectively solving the degradation problem of polyacrylamide in sludge dewatering liquid from waterworks and providing a key biological treatment link for achieving complete reuse of industrial wastewater.

[0029] Optionally, S5 uses a ceramic membrane for filtration, with a pore size no larger than 0.5 μm; during filtration, the pure water flux of the ceramic membrane is 200 L / m³. 2 ·h300 L / m 2 •h, operating pressure is 0.1 MPa to 0.4 MPa.

[0030] Specifically, as an inorganic membrane material, ceramic membranes have higher chemical stability, thermal stability, mechanical strength and longer service life compared to organic membranes. They can withstand a wider pH range and stronger oxidants, thereby reducing membrane fouling and cleaning frequency.

[0031] In this optional embodiment, a ceramic membrane is used for filtration, with its pore size strictly controlled to be no larger than 0.5 μm. This effectively removes trace amounts of polyacrylamide, fine suspended solids, microbial debris, and other colloidal substances from the effluent of bioreactor 3. This high-precision physical barrier significantly reduces the turbidity and organic load of the filtrate, thus effectively solving the problems of increased load, reduced efficiency, and substandard effluent quality in the subsequent ozone oxidation process caused by improper filtration. Simultaneously, the pure water flux of the ceramic membrane is controlled at 200 L / m³. 2 ·h to 300 L / m2 With an operating pressure ranging from 0.1 MPa to 0.4 MPa, the system ensures treatment efficiency while maintaining the operational stability and energy consumption control of the membrane modules, effectively extending membrane lifespan and reducing operating costs. Given the excellent chemical stability and mechanical strength of ceramic membranes, they can adapt to the complex water quality of sludge filtrate from water treatment plants, ensuring water quality stability and process reliability throughout continuous operation. This provides high-quality feed water for subsequent ozone oxidation and UV sterilization, ultimately guaranteeing the safe reuse of the treated water.

[0032] Optionally, in S5, the ozone dosage for ozone oxidation is 5 mg / L to 10 mg / L.

[0033] In this optional embodiment, an ozone oxidation process is introduced after membrane filtration, and the ozone dosage is precisely controlled within the range of 5 mg / L to 10 mg / L. This utilizes the strong oxidizing power of ozone to specifically treat the filtrate after membrane filtration. Ozone can effectively destroy the molecular structure of residual organic matter, especially recalcitrant organic matter and acrylamide monomers remaining after biodegradation, converting them into smaller molecules that are easier to treat or harmless through oxidation. Limiting the ozone dosage to the range of 5 mg / L to 10 mg / L ensures sufficient oxidation and degradation of residual organic pollutants while avoiding increased operating costs and potential by-product risks caused by excessive ozone dosage. This ensures that the treated water quality meets reuse requirements, achieving deep purification of production wastewater and effectively solving the problem that some recalcitrant organic pollutants or trace amounts of acrylamide monomers may remain after membrane filtration, resulting in effluent quality that does not fully meet reuse standards.

[0034] Optionally, in S5, the ultraviolet light irradiation wavelength is 254 nm and the intensity is 10 mJ / cm. 2 Up to 100 mJ / cm 2 The irradiation time is 5 to 20 minutes.

[0035] Specifically, the ultraviolet light irradiation wavelength is 254 nm. This wavelength is in the UVC band, which is one of the wavelengths with the highest absorption efficiency for microbial DNA and RNA.

[0036] In this optional embodiment, introducing an ultraviolet (UV) sterilization step into the filtrate after ozone oxidation treatment can effectively solve the problem of potential microbial or pathogen residues after ozone oxidation. Specifically, UV light with a wavelength of 254 nm can efficiently destroy the genetic material of microorganisms, rendering them unable to reproduce; 10 mJ / cm 2 Up to 100 mJ / cm 2The irradiation intensity ensures sufficient energy to penetrate the water and act on microorganisms; the irradiation time of 5 to 20 minutes guarantees sufficient exposure opportunities for microorganisms. This multi-layered protection mechanism completely eliminates any residual microbial activity in the water, thereby significantly improving the biosafety of the treated water. Compared with ozone oxidation alone, ultraviolet sterilization, as a physical sterilization method, has the characteristics of broad spectrum, high efficiency, and no secondary pollution. Working synergistically with ozone oxidation, it forms a solid biosafety barrier, ensuring that the treated water quality fully meets reuse standards and achieving the safe recycling of production wastewater.

[0037] Optionally, in S2, the frequency of the ultrasound is from 15 kHz to 50 kHz, and the power density is 0.1 W / cm². 2 Up to 1.5 W / cm 2 The duration is 3 to 20 minutes to ensure that the large molecular organic matter in the sludge dewatering liquid from the waterworks is fully broken down.

[0038] In this optional embodiment, by controlling the ultrasonic frequency between 15 kHz and 50 kHz, the local high temperature, high pressure, and shear force generated by the ultrasonic cavitation effect can be fully utilized to efficiently destroy the complex structure of macromolecular organic compounds such as polyacrylamide, decomposing them into smaller, more biodegradable molecular fragments. Simultaneously, the power density is controlled at 0.1 W / cm². 2 Up to 1.5 W / cm 2 This approach ensures that the energy input reaches the threshold for effectively breaking down large molecular chains while avoiding excessive energy consumption, achieving a balance between treatment efficiency and economy. Furthermore, the duration of 3 to 20 minutes guarantees sufficient ultrasonic action, allowing for the complete breakdown of large organic molecules in the filtrate. This precisely controlled ultrasonic pretreatment significantly reduces the molecular weight and complexity of recalcitrant organic matter in the sludge filtrate from the waterworks, thereby greatly reducing the organic load on the subsequent biological reactor 3 and improving the efficiency and stability of biodegradation. Simultaneously, the ultrasonically pretreated filtrate effectively breaks down large molecules, enabling the subsequent preliminary screening pretreatment (S2) to more efficiently remove scum and easily deposited matter, avoiding the impact of large molecular entanglement or clogging on screening results. Ultimately, this pretreatment step lays the foundation for the smooth implementation of the entire sludge filtrate treatment method (including biodegradation, membrane filtration, ozone oxidation, and ultraviolet disinfection), ensuring the thoroughness of wastewater treatment and providing a crucial guarantee for the safe reuse of all production wastewater.

[0039] Optionally, in S3, the ratio of sludge dewatering liquid from the waterworks to domestic sewage is 1:1 to 1:5. The sludge dewatering liquid from the waterworks and domestic sewage are mixed by a paddle mixer with a paddle mixer speed of 60 r / min to 120 r / min and the pH is adjusted to 6.5 to 7.5.

[0040] In this optional embodiment, precise control of the mixing ratio, stirring method, and pH value creates an optimal substrate environment for the subsequent biodegradation process. By limiting the mixing ratio of the filtrate and domestic sewage, it is ensured that the abundant carbon, nitrogen, phosphorus, and mineral nutrients and mineral elements in the domestic sewage are sufficiently diluted and neutralized to neutralize the high concentration of polyacrylamide and other chemical agents in the filtrate, thereby providing a suitable nutrient balance for microorganisms. Using a paddle mixer with a limited rotation speed ensures efficient mass transfer and uniform mixing of the two wastewaters in the mixing tank, avoiding excessively high local concentrations that could harm microorganisms, while also ensuring the homogeneity of the mixture. By adjusting the pH to a neutral range, not only are the physiological needs of microbial growth and metabolism met, but the chemical stability of polyacrylamide during the biodegradation process is also optimized, significantly improving the biodegradation efficiency and operational stability of the entire treatment system, ensuring the smooth progress of subsequent biodegradation steps and the stability of the treatment effect.

[0041] Another embodiment of the present invention provides a treatment system for sludge dewatering liquid from a waterworks, used to operate the above-mentioned treatment method for sludge dewatering liquid from a waterworks, comprising a regulating tank 1, a mixing tank 2, a biological reactor 3, a microfiltration membrane tank 4, an ozone contact tank 5, and an ultraviolet treatment channel 6 connected in sequence. Equalization tank 1 is used to receive sludge filter liquid from the waterworks and perform ultrasonic treatment and preliminary screening pretreatment. Mixing tank 2 is used to receive the effluent from equalization tank 1 and mix it with domestic sewage to adjust the pH. Biological reactor 3 is used to receive the effluent from mixing tank 2 and inject mature aerobic granular sludge that has been acclimatized and cultivated in situ, so that the biomass is controlled within 4 g / L to 8 g / L. Microfiltration membrane tank 4 is used to receive and filter the effluent from biological reactor 3; Ozone contact tank 5 is used to receive the filtrate from microfiltration membrane tank 4 and perform ozone oxidation. The ultraviolet treatment channel 6 is used to receive the effluent from the ozone contact tank 5 and perform ultraviolet sterilization.

[0042] Specifically, by combining ultrasonic pretreatment with preliminary screening, and introducing domestic sewage to regulate water quality, along with in-situ acclimated aerobic granular sludge for biodegradation, followed by multi-stage deep treatment, polyacrylamide is effectively degraded and its toxicity eliminated, achieving the goal of safe reuse and zero discharge of production wastewater. Specifically, the equalization tank 1, as the first process, effectively breaks down large molecular organic matter in the filter press and removes scum and easily deposited substances through ultrasonic treatment and preliminary screening, reducing the load on subsequent biodegradation. The mixing tank 2 receives the effluent from the equalization tank 1 and mixes it with domestic sewage, utilizing the abundant nutrients and minerals in the domestic sewage to improve the composition of the filter press, making it more easily degraded by microorganisms, while adjusting the pH to create a suitable biological reaction environment. The bioreactor 3 injects mature aerobic granular sludge that has been acclimated in situ, utilizing its high metabolic activity and specific degradation ability for polyacrylamide to biologically transform organic pollutants in the wastewater. The stability of the degradation process is ensured by controlling the biomass within the range of 4 g / L to 8 g / L. Microfiltration membrane tank 4 receives and filters the effluent from biological reactor 3, further removing suspended solids and residual particles to ensure clear effluent. Ozone contact tank 5 receives the filtrate from microfiltration membrane tank 4 and performs ozone oxidation, utilizing the strong oxidizing properties of ozone to deeply degrade residual organic pollutants and acrylamide monomers. Ultraviolet treatment channel 6 serves as a final-end protection, receiving the effluent from ozone contact tank 5 and sterilizing it with ultraviolet light to thoroughly eliminate pathogenic microorganisms in the water, ensuring that the final effluent meets safe reuse standards.

[0043] In this embodiment, a closed-loop treatment process is realized, encompassing macromolecular fragmentation, biodegradation, membrane filtration, deep oxidation, and disinfection. Due to the organic integration and functional complementarity of each treatment unit, the biotoxicity of polyacrylamide in the filtrate is effectively resolved, avoiding environmental risks associated with discharge, and the efficiency of water resource recycling is significantly improved. Overall, this technological concept addresses the specific challenges of treating industrial wastewater from waterworks, providing a reliable technical path to achieving the goal of safe reuse and zero discharge of all industrial wastewater through the systematic integration of physical, chemical, and biological treatment methods.

[0044] Optionally, it also includes a thickening tank 7 for receiving scum and easily deposited material removed from the equalization tank 1, and for receiving filter residue from the microfiltration membrane tank 4.

[0045] In this optional embodiment, a centralized collection and treatment mechanism for solid waste within the system is established by adding a thickening tank 7. In the equalization tank 1 stage, scum and easily deposited matter removed through ultrasonic treatment and preliminary screening, as well as filter residue generated by ceramic membrane filtration in the microfiltration membrane tank 4 stage, are all uniformly collected in the thickening tank 7. This design integrates the originally dispersed waste treatment processes, enabling the system to effectively manage the generated solid byproducts while treating the filtrate. By co-introducing the pretreated products from the equalization tank 1 and the filtered products from the membrane tank into the thickening tank 7, synergistic concentration of solid waste from different treatment stages is achieved. This not only simplifies the subsequent sludge disposal process but also avoids the environmental risks caused by the retention or indiscriminate discharge of these solid wastes within the system. This further improves the closed-loop operation capability of the water plant's production wastewater treatment system, ensuring the cleanliness and resource utilization of the entire treatment process.

[0046] Optionally, it also includes a backwashing device 8 for backwashing the ceramic membrane of the microfiltration membrane tank 4, with the backwash water being returned to the purified water distribution well 9, and the effluent from the ultraviolet treatment channel 6 being returned to the purified water distribution well 9.

[0047] In this optional embodiment, a closed-loop water circulation system is constructed. The application of backwashing equipment 8 effectively solves the problem of fouling of the ceramic membrane in the microfiltration membrane tank 4, thereby ensuring the long-term stable operation of the membrane filtration unit and the continuous compliance of the effluent water quality. Simultaneously, the design of returning backwash water to the purified water distribution well 9 avoids the direct discharge of backwash wastewater, incorporating it into the water purification process for further treatment, effectively preventing secondary pollution and realizing the internal recycling of water resources. Furthermore, the effluent from the ultraviolet treatment channel 6 is returned to the purified water distribution well 9, enabling the deeply treated sludge dewatering liquid to be completely reused in the waterworks' production process, thus achieving the goal of full reuse of production wastewater and "zero discharge." This dual-recirculation mechanism not only significantly improves the overall water resource recovery rate of the waterworks but also ensures that the entire system efficiently treats the sludge dewatering liquid from the waterworks while meeting stringent environmental protection requirements, realizing the recycling and sustainable development of water resources.

[0048] The present invention will be further described below with reference to specific embodiments.

[0049] Example 1: Treatment system for sludge dewatering liquid from a waterworks, such as... Figure 2 As shown, it includes: The system comprises: 1. an equalization tank modified with embedded ultrasonic and screening pretreatment units; 2. a mixing tank for pH adjustment and introduction of domestic sewage; 3. a bioreactor based on aerobic granular sludge; 4. a microfiltration membrane tank for particulate matter interception; 5. an ozone contact tank for ozone oxidation; and 6. an ultraviolet treatment channel for ultraviolet sterilization. The inlet of equalization tank 1 is used to receive the PAM-rich filter press liquid produced by the sludge dewatering workshop; the effluent from equalization tank 1, after ultrasonic and screening pretreatment, is connected to mixing tank 2 via pipeline; the bottom sludge and scum generated in equalization tank 1 are fed into the thickening tank 7 in the wastewater treatment process of the water plant.

[0050] One end inlet of the mixing tank 2 is used to receive the filter liquid that has been pretreated by the equalization tank 1, and the other end inlet is used to receive the domestic sewage generated in the water plant, while simultaneously adjusting the pH. The effluent from the mixing tank 2, after being mixed with the domestic sewage and adjusted for pH, is connected to the biological reactor 3 through a pipeline.

[0051] The inlet of the bioreactor is used to receive the filtrate that has been pretreated by the equalization tank 1 and conditioned by the mixing tank 2. Its effluent is connected to the microfiltration membrane tank 4 through a pipeline. The bioreactor 3 is a sequencing batch reactor, which contains mature aerobic granular sludge with high PAM degradation activity that has been acclimatized and cultivated in situ.

[0052] The inlet of the microfiltration membrane tank 4 is used to receive the filtrate after treatment by the previous unit, and its effluent is connected to the ozone contact tank 5 through a pipeline; the concentrated water generated in the microfiltration membrane tank 4 is fed into the concentration tank 7 in the water plant's production wastewater treatment process; the backwash water generated in the microfiltration membrane tank 4 is returned to the water distribution well in the water plant's water purification process; the microfiltration membrane tank 4 has a built-in ceramic membrane module with a membrane pore size of about 0.3 μm, and is equipped with a membrane module backwashing device 8.

[0053] The inlet of ozone contact tank 5 is used to receive the filtrate that has been treated by the preceding unit, and its effluent is connected to the ultraviolet treatment channel 6 through a pipeline; the ozone required in ozone contact tank 5 comes from the ozone generator to ensure an ozone contact time of about 8 minutes.

[0054] The inlet of the ultraviolet treatment channel 6 is used to receive the filtrate that has been treated by the preceding unit, and its effluent can be directly reused in the water distribution well of the water purification process in the water plant; the ultraviolet treatment channel 6 is equipped with an ultraviolet lamp tube, and the ultraviolet light irradiation wavelength is set to 254 nm.

[0055] Example 2, a method for treating sludge filtrate from a waterworks, based on the sludge filtrate treatment system of Example 1, includes the following steps: 1. An ultrasonic device is installed in the equalization tank 1, with its frequency set at 35 kHz, power density controlled at 1 W / cm2, and duration at 10 min, to ultrasonically treat the sludge filter liquid from the waterworks, breaking down large molecular organic matter in the wastewater; a 1 mm mesh screen is used to perform preliminary screening and pretreatment on the ultrasonically treated sludge filter liquid from the waterworks to remove scum and easily deposited matter; in the mixing tank 2, the sludge filter liquid from the waterworks and domestic sewage are mixed at a volume ratio of 1:3, with the paddle stirring speed at 100 r / min, and then hydrochloric acid is added to adjust the pH to 7.0; 2. Prepare artificial simulated domestic sewage. The chemical oxygen demand of the artificial simulated domestic sewage is 300 mg / L, and the artificial simulated domestic sewage includes ammonia nitrogen 55 mg / L, phosphorus 7 mg / L and polyacrylamide 0.3 mg / L. During the start-up phase of bioreactor 3, a sequential batch operation method with six cycles of 4 hours each was adopted, including five stages: influent, anoxic, aeration, sedimentation, and drainage. The ratio of anoxic to aeration time was 0.3, the influent and drainage time were both 5 minutes, and the sedimentation time gradually decreased from 30 minutes in the first cycle to 5 minutes in the sixth cycle to promote the granulation of aerobic granular sludge; the aeration rate was 2 cm / s. The influent was switched to a mixture of sludge dewatering liquid from the waterworks and domestic sewage. By adjusting the mixing ratio of the sludge dewatering liquid from the waterworks and domestic sewage, the concentration of polyacrylamide was gradually increased from 5 mg / L to 50 mg / L in five stages (5 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, 50 mg / L). During the stabilization phase of bioreactor 3, an intermittent operation method with each cycle lasting 6 hours was adopted, including five stages: water inlet, anoxic, aeration, sedimentation, and drainage. The ratio of the time period for anoxic to aeration was 0.3, the time periods for water inlet and drainage were both 5 minutes, and the sedimentation time period was fixed at 5 minutes. The aeration rate was 2 cm / s. Inject mature aerobic granular sludge that has been acclimatized and cultivated in situ to keep the biomass below 6 g / L; 3. Microfiltration is performed in microfiltration membrane tank 4, where the pure water flux of the ceramic membrane is 270 L / m³. 2 •h, operating pressure approximately 0.3 MPa, removes fine suspended solids and particulate organic matter; based on the treated water volume and membrane fouling status, determine the backwashing cycle and operating parameters of the ceramic membrane, and directly return the backwash water to the water distribution well in the water treatment process of the water plant.

[0056] 4. The filtrate is further oxidized by ozone in ozone contact tank 5 to further oxidize soluble and recalcitrant organic matter. The ozone dosage is 7 mg / L to further treat the soluble and recalcitrant organic matter. 5. Ultraviolet light sterilization is performed in ultraviolet treatment channel 6 to inactivate bacteria, viruses, and other microorganisms in the wastewater. The ultraviolet light intensity is controlled at 60 mJ / cm². 2 The irradiation time is approximately 15 minutes. The effluent, after being treated in all previous stages, is directly introduced into the water distribution well in the water plant's water purification process for reuse.

[0057] Effect Example In the start-up phase of biological reactor 3, it is mainly used for the cultivation of mature AGS. The changes in the characteristics of aerobic granular sludge are as follows: Figure 3 As shown. Figure 3 It can be seen that after introducing 0.3 mg / L PAM into bioreactor 3 with artificially prepared water, the particle size of aerobic granular activated sludge can exceed 0.2 mm after 10 days. After another 20 days of operation, the particle size tends to stabilize at about 1.3 mm. During the granulation process, the settling performance of aerobic granular sludge gradually improves, and finally the sludge volume index (SVI) after 30 minutes is achieved. 30 The mixed liquor suspended solids (MLSS) concentration of the aerobic granular sludge in the reaction tank was approximately 39 mL / g. The MLSS concentration first decreased, then increased, and finally stabilized, generally ranging from 4 g / L to 6 g / L. These results indicate that the addition of PAM facilitates the rapid granulation of flocculent aerobic granular sludge, and can cultivate high-performance mature AGS in approximately 30 days.

[0058] During the long-term operation of bioreactor 3, the mature AGS is mainly used to treat the PAM-rich filter press wastewater. Figure 4 The study investigated the changes in chemical oxygen demand (COD) and nitrogen removal (TN) removal efficiency of a sludge dewatering filtrate safe reuse system. The results showed that the PAM content in the wastewater increased from 5 mg / L to 50 mg / L with the extension of operating time, the COD removal rate gradually decreased but remained above 75%, and the TN removal rate was between 45% and 55%. This indicates that the addition of domestic sewage to the system can synergistically treat the PAM dewatering filtrate.

[0059] To investigate the main degradation pathway of PAM in the filtrate and the contribution of mature aerobic granular sludge, Tables 1 and 2 compare the removal of PAM from the filtrate and the PAM degradation capacity of AGS in the bioreactor 3 of Example 2 under two conditions: one with mature AGS that has undergone prior acclimation and cultivation, and the other with ordinary AGS that has not undergone prior acclimation and cultivation. In Tables 1 and 2, stages 1-5 correspond to the gradual increase of polyacrylamide concentration from 5 mg / L to 50 mg / L in five stages in Example 2 (i.e., stage 1 corresponds to a polyacrylamide concentration of 5 mg / L, stage 2 to a polyacrylamide concentration of 10 mg / L, stage 3 to a polyacrylamide concentration of 20 mg / L, stage 4 to a polyacrylamide concentration of 30 mg / L, and stage 5 to a polyacrylamide concentration of 50 mg / L). It can be seen that the PAM removal rate of the former is generally between 80% and 92%, and the PAM content in the effluent is less than 5 mg / L. The degradation rate of mature AGS is greater than 2.3 mg / L·h, which is significantly higher than the degradation rate of AGS without prior domestication (1.5 mg / L·h to 1.8 mg / L·h). This indicates that the cultured mature AGS has high PAM degradation activity, and the removal of PAM in the filtrate mainly depends on the biodegradation of AGS.

[0060] Table 1. Performance of mature AGS in degrading PAM during early domestication culture.

[0061] Table 2. Performance of AGS in degrading PAM without prior domestication.

[0062] To investigate the effect of PAM-containing filtrate on the characteristics of aerobic granular sludge, Table 3 summarizes the changes in granular sludge characteristics at different stages of initial acclimation. In Table 3, stages 1-5 correspond to the gradual increase of polyacrylamide concentration from 5 mg / L to 50 mg / L in five stages, as described in Example 2 (i.e., stage 1 corresponds to a polyacrylamide concentration of 5 mg / L, stage 2 to 10 mg / L, stage 3 to 20 mg / L, stage 4 to 30 mg / L, and stage 5 to 50 mg / L). The results show that with the increase of PAM content in the influent, the aerobic granular sludge consistently maintained good settling performance, and the SVI (Self-Isolation Value) was [not specified]. 30 The particle size of aerobic granular sludge was below 65 mL / g; the particle size of the sludge first decreased and then increased, indicating that the mature AGS gradually adapted to the increase in PAM content and developed excellent PAM degradation ability.

[0063] Table 3. Particle size and sedimentation properties of mature AGS

[0064] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for treating sludge filtrate from a waterworks, characterized in that, Includes the following steps: S1: Ultrasonic treatment of sludge filtrate from waterworks; S2: The ultrasonically treated sludge filter liquid from the waterworks is subjected to preliminary screening pretreatment to remove scum and easily deposited substances. S3: Introduce domestic sewage and adjust the pH; S4: Inject mature aerobic granular sludge that has been acclimatized and cultivated in situ, so that the biomass is controlled within 4 g / L to 8 g / L; S5: Filtration, the filtrate is then subjected to ozone oxidation; S6: Ultraviolet sterilization.

2. The method for treating sludge filtrate from a waterworks according to claim 1, characterized in that, In step S4, the in-situ acclimatization and cultivation method for mature aerobic granular sludge includes the following steps: S41: Prepare artificial simulated domestic sewage, wherein the chemical oxygen demand of the artificial simulated domestic sewage is 200 mg / L to 400 mg / L, and the artificial simulated domestic sewage includes ammonia nitrogen of 50 mg / L to 60 mg / L, phosphorus of 5 mg / L to 10 mg / L and polyacrylamide of 0.1 mg / L to 0.5 mg / L; S42: An intermittent operation method with each cycle lasting 3 to 6 hours is adopted, including five stages: water inflow, anoxic conditions, aeration, sedimentation, and drainage. The ratio of the time period for anoxic conditions to that for aeration is 0.2 to 0.

4. The time periods for water inflow and drainage are both 3 to 8 minutes. The sedimentation time gradually decreases from 25 to 35 minutes in the first cycle to 3 to 8 minutes in the last cycle to promote the granulation of the aerobic granular sludge. The aeration rate is 1 cm / s to 3 cm / s. S43: The influent is switched to a mixture of the sludge dewatering liquid from the waterworks and the domestic sewage. By adjusting the mixing ratio of the sludge dewatering liquid from the waterworks and the domestic sewage, the concentration of the polyacrylamide is gradually increased from 3 mg / L to 5 mg / L to 30 mg / L to 50 mg / L. S44: An intermittent operation method with each cycle lasting 2 to 8 hours is adopted, including five stages: water inlet, anoxic, aeration, sedimentation, and drainage. The ratio of the time period for anoxic to aeration is 0.2 to 0.4, the time periods for water inlet and drainage are both 3 to 8 minutes, and the time period for sedimentation is fixed at 3 to 8 minutes. The aeration rate is 1 cm / s to 3 cm / s.

3. The method for treating sludge filtrate from a waterworks according to claim 1, characterized in that, The S5 step uses a ceramic membrane for filtration, the pore size of which is no greater than 0.5 μm; during the filtration process, the pure water flux of the ceramic membrane is 200 L / m³. 2 ·h300 L / m 2 •h, operating pressure is 0.1 MPa to 0.4 MPa.

4. The method for treating sludge filtrate from a waterworks according to claim 1, characterized in that, In step S5, the ozone dosage for ozone oxidation is 5 mg / L to 10 mg / L.

5. The method for treating sludge filtrate from a waterworks according to claim 1, characterized in that, In step S5, the ultraviolet light irradiation wavelength is 254 nm and the intensity is 10 mJ / cm. 2 Up to 100 mJ / cm 2 The irradiation time is 5 to 20 minutes.

6. The method for treating sludge filtrate from a waterworks according to claim 1, characterized in that, In step S2, the frequency of the ultrasonic wave is 15 kHz to 50 kHz, and the power density is 0.1 W / cm². 2 Up to 1.5 W / cm 2 The duration is 3 to 20 minutes to ensure that the large molecular organic matter in the sludge dewatering liquid from the waterworks is fully broken down.

7. The method for treating sludge filtrate from a waterworks according to claim 1, characterized in that, In step S3, the ratio of the sludge dewatering liquid from the waterworks to the domestic sewage is 1:1 to 1:

5. The sludge dewatering liquid from the waterworks and the domestic sewage are mixed by a paddle mixer with a stirring speed of 60 r / min to 120 r / min and the pH is adjusted to 6.5 to 7.

5.

8. A treatment system for sludge dewatering liquid from a waterworks, characterized in that, The method for treating sludge filtrate from a waterworks as described in any one of claims 1-7 includes, in sequence, an equalization tank (1), a mixing tank (2), a biological reactor (3), a microfiltration membrane tank (4), an ozone contact tank (5), and an ultraviolet treatment channel (6). The equalization tank (1) is used to receive the sludge filter liquid from the waterworks and to perform ultrasonic treatment and preliminary screening pretreatment. The mixing tank (2) is used to receive the effluent from the regulating tank (1) and domestic sewage for mixing and pH adjustment; The bioreactor (3) is used to receive the effluent from the mixing tank (2) and inject mature aerobic granular sludge that has been acclimatized and cultivated in situ, so that the biomass is controlled within 4 g / L to 8 g / L. The microfiltration membrane tank (4) is used to receive the effluent from the biological reactor (3) and filter it; The ozone contact tank (5) is used to receive the filtrate from the microfiltration membrane tank (4) and perform ozone oxidation. The ultraviolet treatment channel (6) is used to receive the effluent from the ozone contact tank (5) and perform ultraviolet sterilization.

9. The treatment system for sludge dewatering liquid from a waterworks according to claim 8, characterized in that, It also includes a thickening tank (7) for receiving scum and easily deposited material removed from the equalization tank (1) and for receiving filter residue from the microfiltration membrane tank (4).

10. The treatment system for sludge dewatering liquid from a waterworks according to claim 8, characterized in that, It also includes a backwashing device (8) for backwashing the ceramic membrane of the microfiltration membrane tank (4), the backwash water is returned to the purified water distribution well (9), and the effluent from the ultraviolet treatment channel (6) is returned to the purified water distribution well (9).

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