A device for synergistically controlling disinfection by-products and conditional pathogens of surface water by low-temperature-resistant combined process of bank filtration and nanofiltration and a working method thereof

Abstract

The application provides a device for synergistically controlling disinfection by-products and conditional pathogenic bacteria of surface water by a low-temperature-resistant bank filtration-nanofiltration combined process and a working method thereof, and belongs to the technical field of water treatment and efficient water resource utilization. An aeration disc is arranged at the inner bottom of a raw water tank in the device, a bank filtration simulation column is filled with multiple layers of filter materials, the outlet end of the raw water tank is communicated with the water inlet of the bank filtration simulation column through a peristaltic pump, the water inlet of the bank filtration simulation column is located above the bank filtration simulation column, the water outlet at the lowermost part of the bank filtration simulation column is communicated with the water inlet of a bank filtration water collecting tank, the water outlet of the bank filtration water collecting tank is communicated with the water inlet of a nanofiltration membrane assembly, the clean water outlet of the nanofiltration membrane assembly is communicated with a nanofiltration water collecting tank, and the concentrated water outlet of the nanofiltration membrane assembly is communicated with a nanofiltration concentrated water tank. The device can solve the problem of unstable water quality of bank filtration caused by environmental factors, and can also alleviate the membrane pollution problem of nanofiltration technology through bank filtration pretreatment.

Description

Technical Field

[0001] This invention belongs to the field of water treatment and efficient water resource utilization technology, and in particular relates to a device and its working method for the synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process. Background Technology

[0002] Dissolved organic matter (DOM) in surface water inevitably reacts with chlorinated disinfectants during the disinfection process, resulting in disinfection byproducts. The generation of DBPs (Disinfection Byproducts). These disinfection byproducts often pose carcinogenic risks and have reproductive and developmental toxicity. Opportunistic pathogens are a special type of pathogenic microorganism that usually maintain a good symbiotic balance with humans. However, when this balance is disrupted (e.g., due to weakened immunity), these bacteria, which were originally non-pathogenic to humans, become pathogenic. Opportunistic pathogens are highly resistant to chlorine and are usually unaffected by chlorination disinfectants. Therefore, controlling DBPs and opportunistic pathogens in surface water remains a crucial aspect of water treatment before chlorination disinfection.

[0003] Nanofiltration (NF) is a pressure-driven membrane separation technology that emerged in the late 20th century. Its separation mechanism combines size sieving, Donald's repulsion, and dielectric repulsion, selectively retaining most divalent ions and some monovalent ions (20%–80%), exhibiting both high efficiency and low energy consumption. Nanofiltration operates at pressures ranging from 0.3 to 1.0 MPa, achieving highly efficient separation of nanoscale particles in solution. It effectively intercepts trace organic matter, disinfection byproducts, opportunistic pathogens, and carcinogenic and teratogenic substances in water, improving the biosafety level of drinking water. Furthermore, it ensures the stability of water quality in water supply systems during sudden water pollution incidents and can adapt to diverse raw water treatment needs. However, the excellent pollutant retention performance of nanofiltration leads to the accumulation of more pollutants on the membrane surface, exacerbating membrane fouling. Therefore, pretreatment is necessary when applying nanofiltration technology as a water purification process to mitigate membrane fouling.

[0004] Riverbank filtration (RBF) is a nature-based water treatment technology that induces surface water to flow through sediment layers into RBF wells under the influence of hydraulic gradients. During this process, physical, chemical, and biological processes in the environment purify the water to meet human needs. This technology utilizes the riverbanks, aquifers, and groundwater near the water source, using natural ecological mechanisms as a natural barrier for water treatment, exhibiting significant natural ecological attributes compared to artificial technologies. RBF has a significant removal effect on DOM (deterministic organic pollutants) that can react with disinfectants to form DBPs, and it can also effectively adsorb and degrade opportunistic pathogens through filter media. Therefore, coupling RBF with nanofiltration to form a RBF-nanofiltration combined process can efficiently reduce DBP precursors, thereby inhibiting DBP production and synergistically controlling opportunistic pathogens in the effluent. However, as an independent water purification technology, RBF is often affected by environmental factors such as temperature, water pollution, and extreme climates during operation, leading to instability in the quality of its effluent. Low temperatures have a significant impact on shore filtration processes. Under low-temperature stress, the metabolic enzyme activity and cell proliferation rate of microbial communities in shore filtration processes decrease, leading to a significant reduction in their pollutant treatment efficiency. Therefore, developing a low-temperature resistant shore filtration-nanofiltration combined process to synergistically control surface water disinfection byproducts and conditionally pathogenic bacteria is key to overcoming current technological limitations. Summary of the Invention

[0005] In view of this, in order to address the problem of residual DBPs and conditionally pathogenic bacteria in surface water after chlorination disinfection, this invention proposes a device and its operating method for synergistic control of disinfection byproducts and conditionally pathogenic bacteria in surface water using a low-temperature resistant shore filtration-nanofiltration combined process. This device can remove DOMs (disinfectant precipitates) that can react with chlorination disinfectants to generate DBPs, as well as conditionally pathogenic bacteria, during the surface water treatment process. Furthermore, by enriching the internal filter media with cold-resistant microorganisms under long-term low-temperature operation conditions of the shore filtration, it improves the problems of unstable effluent quality and reduced pollutant treatment efficiency caused by the low-temperature environment. It also alleviates membrane fouling problems associated with nanofiltration technology through shore filtration pretreatment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A device for synergistic control of disinfection byproducts and opportunistic pathogens in surface water using a low-temperature resistant shore filtration-nanofiltration combined process, comprising: Raw water tank, with an aeration disc installed at the bottom of the raw water tank; The shore filter simulation column is filled with multiple layers of filter media. The outlet of the raw water tank is connected to the inlet of the shore filter simulation column through a peristaltic pump. The inlet of the shore filter simulation column is located at the top of the shore filter simulation column. The bottom outlet of the shore filter collection tank is connected to the inlet of the shore filter collection tank. The outlet of the nanofiltration membrane module is connected to the inlet of the shore filter water collection tank; Nanofiltration water collection tank; the purified water outlet of the nanofiltration membrane module is connected to the nanofiltration water collection tank. Nanofiltration concentrate tank, the concentrate outlet of the nanofiltration membrane module is connected to the nanofiltration concentrate tank.

[0007] As a preferred embodiment of the device for the synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, the shore filtration simulation column has multiple outlets, which are arranged longitudinally at intervals for analyzing the water purification efficiency of each filter media layer of the shore filtration simulation column and for sampling the filter media during subsequent microbial diversity analysis.

[0008] As a preferred embodiment of the device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, a check valve is provided on the pipeline between the lowest outlet of the shore filtration simulation column and the inlet of the shore filtration collection tank.

[0009] As a preferred embodiment of the device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, the outlet of the shore filtration collection tank is connected to the inlet of the nanofiltration membrane module via a gear pump.

[0010] As a preferred embodiment of the device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, the gear pump is set with an inlet pressure of 0.4-0.6 MPa.

[0011] As a preferred embodiment of the device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, a first outlet valve is installed on the pipeline between the purified water outlet of the nanofiltration membrane module and the nanofiltration water collection tank.

[0012] As a preferred embodiment of the device for the synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria by the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, a second outlet valve is provided on the pipeline between the concentrate outlet of the nanofiltration membrane module and the nanofiltration concentrate tank.

[0013] As a preferred embodiment of the device for the synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, the shore filtration simulation column is made of UPVC / PMMA filter column with an inner diameter of 90-110 mm and an effective filtration height of 50-70 cm.

[0014] As a preferred embodiment of the device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, the nanofiltration membrane module has a nanofiltration membrane model of NF90 / NF270 and an effective molecular weight cutoff of 90 / 270 Da.

[0015] This invention also provides a method for operating a device that uses a low-temperature resistant shore filtration-nanofiltration combined process to synergistically control disinfection byproducts and conditionally pathogenic bacteria in surface water. The device, employing the aforementioned shore filtration-nanofiltration combined process for removing disinfection byproducts from surface water, includes: Inside the raw water tank, the aeration disc provides oxygen to the raw water, and the raw water in the raw water tank is pumped into the inlet of the shore filter simulation column by a peristaltic pump. After the raw water enters the simulated bank filter column, it flows through each filter media layer in sequence for purification and is then discharged into the bank filter water collection tank. The permeate from the shore filtration in the shore filtration collection tank is purified in the nanofiltration membrane module and discharged into the nanofiltration collection tank. At the same time, the concentrate produced during the nanofiltration process is discharged into the nanofiltration concentrate tank.

[0016] Compared with existing technologies, the beneficial effects of the device and its working method for the synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process are as follows: This invention provides a device and its operating method for the synergistic control of disinfection byproducts and conditionally pathogenic bacteria in surface water using a low-temperature resistant shore filtration-nanofiltration combined process. In this device, the shore filtration simulation column employs shore filtration technology to pretreat pollutants in surface water. The shore filtration technology effectively treats DOM (disinfectant precipitates) in the raw water and, under long-term low-temperature operation, enriches the filter media inside the shore filtration column with cold-resistant microorganisms, thereby reducing the content of disinfection byproducts generated by their reaction with chlorination disinfectants and improving treatment efficiency under low-temperature conditions. This water purification process combines biological processes with membrane filtration technology. The shore filtration pretreatment significantly reduces suspended solids, colloids, and other pollutants in the raw water, thus alleviating membrane fouling during the NF (non-fluorescent) process to some extent. The NF post-treatment addresses the problem of unstable water quality in the shore filtration effluent and retains conditionally pathogenic bacteria in the effluent. Specific beneficial effects are as follows: (1) Bank filtration pretreatment controls the generation of DBPs after chlorination disinfection by reducing DOM in the raw water: DOM is removed through the synergistic effect of physical interception, adsorption and biodegradation. The gradient filter layer can effectively intercept suspended particles and colloids and other impurities. In-situ riverbank soil and quartz sand remove carbon-containing precursors such as humic acid and fulvic acid through adsorption. Under long-term filtration, the biofilm on the filter media surface and the microorganisms in the riverbank soil can biodegrade dissolved organic matter and organic nitrogen, which is the core of long-term stable removal. The aerobic-anoxic-anaerobic environment formed along the filter layer can directionally degrade aromatic organic matter and recalcitrant macromolecules, reduce nitrogen-containing and brominated highly toxic by-product precursors, and control the generation of disinfection by-products from the source.

[0017] (2) Controlling conditional pathogens in effluent through shore filtration-nanofiltration combined process: shore filtration pretreatment can first reduce the free and particulate conditional pathogens in surface water through physical interception, adsorption fixation and protozoan predation, reduce the microbial load of influent, remove assimilated organic carbon to inhibit microbial regeneration, reduce the risk of biofouling and bacterial leakage on nanofiltration membrane surface, and then rely on the nanofiltration membrane's nanoscale sieving effect to completely intercept residual bacteria. The dual barrier works together to achieve efficient control of conditional pathogens in effluent.

[0018] (3) Enriching cold-resistant microorganisms on the surface of filter media through long-term operation in a low-temperature environment of the opposite bank filter, thereby improving the treatment efficiency under low-temperature conditions: The constant low-temperature environment can be continuously acclimatized through the opposite bank filter process, retaining the native cold-resistant bacteria source in the original riverbank soil, allowing low-temperature surface water to flow continuously, appropriately extending the hydraulic retention time, reducing the filtration rate, supplementing micronutrients to maintain microbial metabolism, and directionally enriching cold-adapted heterotrophic bacteria, nitrifying bacteria and other cold-resistant functional bacteria groups on the surface of quartz sand and riverbank soil filter media, thereby improving the activity of extracellular degradation enzymes under low temperature, effectively alleviating the problem of inhibited microbial activity and decreased biodegradation performance caused by low temperature.

[0019] (4) Mitigating nanofiltration membrane fouling through shore filtration pretreatment: As a pretreatment for nanofiltration, shore filtration can efficiently remove suspended particulate matter, colloids, macromolecular humic substances and microorganisms from surface water, significantly reducing nanofiltration influent turbidity, organic load and bio-adhesion risk, preferentially removing key membrane pollutants such as biopolymers, reducing filter cake formation and membrane pore blockage, reducing irreversible fouling of the membrane surface, significantly slowing down nanofiltration membrane flux decay, and extending its operating cycle and cleaning interval. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1This is a schematic diagram of a device for synergistic control of disinfection byproducts and conditionally pathogenic bacteria in surface water using a low-temperature resistant shore filtration-nanofiltration combined process, provided in a specific embodiment of the present invention. Figure 2 The removal effects of using shore filtration technology alone, using nanofiltration technology alone, and using a combined shore filtration-nanofiltration process in this embodiment on basic water quality indicators are compared. Figure 3 A comparison of the microbial community structure of internal filter media when using shore filtration technology alone at different operating temperatures; Figure 4 The effects of using shore filtration technology alone, using nanofiltration technology alone, and using a combined shore filtration-nanofiltration process in this embodiment on the removal potential of disinfection byproducts are compared.

[0021] In the picture: 1. Raw water tank; 2. Aeration disc; 3. Outlet of raw water tank; 4. Peristaltic pump; 5. Sealing screw of shore filter simulation column; 6. Inlet of shore filter simulation column; 7. Shore filter simulation column; 8. Outlet of shore filter simulation column; 9. Check valve; 10. Inlet of shore filter collection tank; 11. Shore filter collection tank; 12. Outlet of shore filter collection tank; 13. Gear pump; 14. Screw of nanofiltration membrane module; 15. Inlet of nanofiltration membrane module; 16. Nanofiltration membrane module; 17. Nanofiltration membrane; 18. Concentrate outlet of nanofiltration membrane module; 19. First outlet valve; 20. Inlet of nanofiltration collection tank; 21. Nanofiltration collection tank; 22. Nanofiltration concentrate tank; 23. Second outlet valve; 24. Inlet of nanofiltration concentrate tank. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0023] Example See Figure 1-4This invention provides a device and its operating method for synergistically controlling disinfection byproducts and conditionally pathogenic bacteria in surface water using a low-temperature resistant shore filtration-nanofiltration combined process. The device includes: a raw water tank 1, a shore filtration simulation column 7, a shore filtration collection tank 11, a nanofiltration membrane 17 assembly 16, a nanofiltration collection tank 21, and a nanofiltration concentrate tank 22. An aeration disc 2 is installed at the bottom of the raw water tank 1. The shore filtration simulation column 7... The interior is filled with multiple layers of filter media. The outlet 3 of the raw water tank is connected to the inlet 6 of the shore filter simulation column via a peristaltic pump 4. The inlet 6 of the shore filter simulation column is located above the shore filter simulation column 7. The bottom outlet of the shore filter simulation column 7 is connected to the inlet 10 of the shore filter collection tank. The outlet 12 of the shore filter collection tank is connected to the inlet 15 of the nanofiltration membrane module. The purified water outlet of the nanofiltration membrane module 16 is connected to the nanofiltration collection tank 21. The concentrated water outlet 18 of the nanofiltration membrane module is connected to the nanofiltration concentrated water tank 22.

[0024] The filter media inside the simulated bank filter column 7 includes gravel, quartz sand, and riverbank soil required for bank filtration. In this embodiment, coarse gravel, coarse quartz sand, fine quartz sand, and riverbank soil are filled into the simulated bank filter column 7 from bottom to top.

[0025] The top of the simulated bank filter column 7 is sealed with screws, thus making the entire bank filter device a closed structure. The outlet of the raw water tank 1 is connected to the inlet 6 of at least one simulated bank filter column.

[0026] The raw water in the raw water tank 1 enters the inlet 6 of the bank filter simulation column through the peristaltic pump 4, and then flows through the filter media layers of coarse gravel, coarse quartz sand, fine quartz sand and riverbank soil in sequence. After being purified, it is discharged into the bank filter collection tank 11. Then the bank filter permeate enters the nanofiltration membrane module 16 for purification. The purified water is discharged into the nanofiltration collection tank 21, while the concentrate generated during the nanofiltration process is discharged into the nanofiltration concentrate tank 22.

[0027] This low-temperature resistant shore filtration-nanofiltration combined process is a device for synergistic control of disinfection byproducts and conditionally pathogenic bacteria in surface water. The shore filtration technology can effectively treat DOM contained in the raw water, thereby reducing the content of disinfection byproducts generated by its reaction with chlorination disinfectants. At the same time, the shore filtration technology pre-treats pollutants in the surface water, significantly reducing suspended solids, colloids and other pollutants in the raw water, thus alleviating membrane fouling in the NF process to a certain extent. The NF post-treatment can solve the problem of unstable water quality in the shore filtration effluent.

[0028] Optionally, the aeration disc 2 is connected to an external air source.

[0029] Optionally, the number of outlets 8 of the shore filter simulation column is multiple, and the multiple outlets of the shore filter simulation column 7 are arranged at intervals along the longitudinal direction for use in analyzing the water purification efficiency of each filter media layer of the shore filter simulation column 7 and for sampling the filter media during subsequent microbial diversity analysis.

[0030] Optionally, a check valve 9 is provided on the pipeline between the lowest outlet of the shore filter simulation column 7 and the inlet 10 of the shore filter collection tank.

[0031] Optionally, the outlet 12 of the shore filter water collection tank is connected to the inlet 15 of the nanofiltration membrane module via a gear pump 13.

[0032] Optionally, the gear pump 13 is set with an inlet water pressure of 0.4-0.6 MPa.

[0033] Optionally, a first outlet valve 19 is provided on the pipeline between the purified water outlet of the nanofiltration membrane module 16 and the nanofiltration water collection tank 21.

[0034] Optionally, a second outlet valve 23 is provided on the pipeline between the concentrate outlet 18 of the nanofiltration membrane module and the nanofiltration concentrate tank 22.

[0035] Optionally, the shore filter simulation column 7 is made of UPVC / PMMA filter column with an inner diameter of 90-110 mm and an effective filtration height of 50-70 cm.

[0036] Optionally, the nanofiltration membrane 17 of the nanofiltration membrane module 16 is of type NF90 / NF270, with an effective molecular weight cutoff of 90 / 270 Da. The nanofiltration membrane module 16 and the NF270 nanofiltration membrane 17 adopt existing technology, and their structure and working principle will not be described in detail here.

[0037] This invention also provides a method for operating a device for synergistically controlling disinfection byproducts and opportunistic pathogens in surface water using a low-temperature resistant shore filtration-nanofiltration combined process. The device, employing the aforementioned low-temperature resistant shore filtration-nanofiltration combined process, comprises: Inside the raw water tank 1, the aeration disc 2 provides oxygen to the raw water. The raw water in the raw water tank 1 is pumped into the inlet 6 of the shore filter simulation column by the peristaltic pump 4. Coarse gravel, coarse quartz sand, fine quartz sand, and riverbank soil are filled into the bank filter simulation column 7 from bottom to top. After the raw water enters the bank filter simulation column 7, it flows through each filter layer in sequence for purification and is discharged into the bank filter water collection tank 11. The permeate from the shore filter in the shore filter collection tank 11 is purified in the nanofiltration membrane module 16 and discharged into the nanofiltration collection tank 21. At the same time, the concentrate generated during the nanofiltration process is discharged into the nanofiltration concentrate tank 22.

[0038] In order to control the operation of the shore filter device under low temperature conditions, the temperature in the laboratory is strictly controlled at 13-15℃ during operation, and the temperature fluctuation of the influent and effluent is strictly monitored daily to ensure that it does not exceed 0.2℃ within this temperature range.

[0039] Obviously, the above-disclosed embodiments of the present invention are merely illustrative of the invention. The embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. It is neither necessary nor possible to exhaustively describe all embodiments herein.

[0040] Comparative Example 1 The comparative example using shore filtration technology alone under room temperature conditions is denoted as (CTRBF). Except that during operation, the water quality indicators are directly tested after the shore filtration effluent is discharged without connecting it to the nanofiltration system, and its operating temperature is maintained at 24-26℃ with strict monitoring that the daily temperature fluctuation of the influent and effluent does not exceed 0.2℃ within this temperature range, the rest of the structure, operation mode and experimental conditions of CTRBF are consistent with the aforementioned embodiment.

[0041] Comparative Example 2 A comparative example using shore filtration technology alone under high-temperature conditions, denoted as (HTRBF), involves directly testing water quality indicators after the shore filter effluent during operation, without connecting it to the nanofiltration system, maintaining its operating temperature at 29-31℃, and strictly controlling the daily temperature fluctuation of the influent and effluent within this range to no more than 0.2℃. The remaining structure, operation mode, and experimental conditions of the HTRBF are consistent with the aforementioned examples.

[0042] Comparative Example 3 The comparative example using nanofiltration technology alone is denoted as (NF). Except for the fact that no shore filtration pretreatment is performed during operation and the raw water is directly connected to the nanofiltration system, the structure, operation mode and experimental conditions of NF are consistent with the aforementioned embodiments.

[0043] Comparative Example 4 The room temperature shore filtration-nanofiltration combined process, denoted as CTRBF-NF, is consistent with the aforementioned embodiment in all aspects except that the laboratory temperature is controlled at 22-26℃ during operation, and the daily temperature fluctuation of the influent and effluent is strictly monitored to ensure that it does not exceed 0.2℃.

[0044] Comparative Example 5 The high-temperature shore filtration-nanofiltration combined process, denoted as HTRBF-NF, is consistent with the aforementioned embodiment in all aspects except that the laboratory temperature is controlled at 29-31℃ during operation, and the daily temperature fluctuation of the influent and effluent is strictly monitored to ensure that it does not exceed 0.2℃.

[0045] Comparative experiments between the examples and the comparative examples I. Comparison of the removal effects of basic water quality indicators using shore filtration technology alone, nanofiltration technology alone, and the combined shore filtration-nanofiltration process in this embodiment under room temperature conditions.

[0046] Based on the continuous monitoring results of influent and effluent water samples from each system during the experiment, the RBF, NF, and RBF-NF systems showed positive effects on DOC and UV. 254 NH4 + The removal efficiency of common water quality indicators such as -N and TN is shown in the attached figure. Figure 2 As shown, all systems maintained stable processing performance during the 30-day operational period.

[0047] Comparative Example 1 (RBF) showed a certain removal effect on various basic water quality indicators in surface water, particularly on DOC and UV. 254 NH4 + The average removal efficiencies for -N and TN were 32.07%, 21.42%, 29.85%, and 26.43%, respectively.

[0048] Compared with RBF, nanofiltration (NF) alone improved the removal rates of most indicators. Results showed that NF significantly improved the removal rates of DOC and UV. 254 NH4 + The removal efficiencies of -N and TN were significantly improved compared to RBF, with average removal efficiencies of 45.09%, 33.82%, 55.39%, and 60.58%, respectively. RBF removal of pollutants mainly relies on the synergistic effect of physical retention, interfacial adsorption, and microbial biodegradation of the filter layer. Its filter layer pores can only effectively retain colloidal and particulate organic matter and nitrogen-containing substances; its retention capacity for small molecule dissolved organic matter and inorganic nitrogen is weak. It can only remove a portion of biodegradable DOC and NH4 through biological processes. + -N, for UV 254The removal capacity of recalcitrant aromatic organic compounds was limited, resulting in low removal rates for all four indicators. Nanofiltration, however, utilizes the physical sieving of nanoscale membrane pores and the charge repulsion on the membrane surface as its core removal mechanism. It can efficiently retain dissolved organic matter and aromatic humic substances with molecular weights above 200 Da, while simultaneously achieving efficient retention of charged ions in the water through electrostatic interactions, thus simultaneously achieving efficient retention of both organic and inorganic nitrogen. Therefore, its removal efficiency for all four indicators is significantly higher than that of shore filtration alone. However, suspended solids, colloids, and large molecular organic matter in the raw water can easily cause membrane pore blockage and filter cake formation, weakening the membrane's stable retention performance and limiting further improvements in removal efficiency.

[0049] The shore filtration-nanofiltration (RBF-NF) combined process employed in this embodiment demonstrates superior overall treatment efficiency. This system effectively treats DOC and UV... 254 NH4 + The average removal efficiencies of -N and TN were 60.74%, 52.92%, 74.96%, and 83.00%, respectively. In the RBF-NF combined process, RBF pretreatment can remove most suspended particles, colloids, macromolecular humic substances, and some nitrogen-containing pollutants, significantly reducing the nanofiltration feed water load, effectively alleviating membrane fouling, and ensuring the stable performance of the nanofiltration membrane. The two processes form a multi-level purification barrier with synergistic effect, achieving deep removal of various pollutants. Therefore, the removal efficiency of the four indicators is significantly better than that of the first two single processes.

[0050] II. Comparison of the effects of using shore filtration technology alone on the internal microbial community structure of filter media under low temperature conditions, room temperature conditions, and high temperature conditions; enrichment of cold-resistant microorganisms; and control of conditionally pathogenic bacteria.

[0051] After the effluent water quality indicators stabilized, the filter media in the simulated shore filter column was extracted for microbial community diversity analysis at the phylum and genus levels. The results are shown in the attached figure. Figure 3 As shown. At the level of the door, Pseudomonadota Phylum is the dominant group and the core cold-resistant group, with its abundance showing the order RBF (45.78%) > CTRBF (30.88%) > HTRBF (22.51%), exhibiting a clear trend of enrichment at low temperatures. Chloroflexota Gate (HTRBF: 12.81%, CTRBF: 11.70%, RBF: 6.64%) and Bacteroidota Phylum (HTRBF: 11.03%, RBF: 6.93%, CTRBF: 1.98%) showed a preference for high temperatures; at the genus level, unclassified phyla... Anaerolineaceae Microorganisms were most abundant in the HTRBF group (6.33%). Clostridium It performed best in the CTRBAF group (5.17%). NitrospiraThe genus showed the best performance in the RBF group (2.92%), exhibiting a low-temperature enrichment trend.

[0052] Regarding the control of opportunistic pathogens, the results showed that temperature significantly affected the abundance and distribution of opportunistic pathogen groups, with different groups exhibiting differentiated temperature response patterns: at the phylum level... Bacillota Phylum (including pathogenic bacteria such as Clostridium) had the highest abundance in the CTRBF group (10.93%). Bacteroidota Phylum (including pathogenic bacteria such as Bacteroides) had the highest abundance in the HTRBF group (11.03%); at the genus level, Clostridium The abundance of the genus Clostridium (including Clostridium perfringens, Clostridium botulinum, and other pathogenic bacteria) reached its peak in the CTRBF group (5.17%), which was significantly higher than that in the HTRBF group (2.33%) and the RBF group (1.46%). Dechloromonas The genus *Dechloromonas*, with some strains being opportunistic pathogens, had the highest abundance in the HTRBF group (2.39%).

[0053] III. The removal effects of using shore filtration technology alone, using nanofiltration technology alone, and using a combined shore filtration-nanofiltration process in this embodiment on the potential for the formation of disinfection byproducts.

[0054] Based on the monitoring results of influent and effluent water samples from each system during the experiment, the removal efficiencies of the RBF, NF, and RBF-NF systems for the formation potential of trichloromethane (TCM) and haloacetic acids are shown in the attached figure. Figure 4As shown in the figure, regarding the control of haloacetic acids, the concentrations of BCAA, DCAA, and TCAA at the influent were 32.67 μg / L, 31.35 μg / L, and 63.25 μg / L, respectively. The single-bank filtration process, relying solely on soil adsorption and microbial degradation, had the lowest removal rate (BCAA: 9.3%, DCAA: 19.0%, TCAA: 17.2%), and showed little difference in the removal of different haloacetic acids. The single nanofiltration process, relying on membrane retention, significantly improved the removal efficiency (BCAA: 32.8%, DCAA: 34.6%, TCAA: 25.1%), with the best retention effect on DCAA. The combined bank filtration-nanofiltration process, through a synergistic mechanism of "pretreatment-deep retention," first reduces the concentration of suspended solids and some organic matter in the water, reduces nanofiltration membrane fouling, and optimizes the retention environment, further increasing the haloacetic acid removal rate to 41.0% (BCAA), 41.4% (DCAA), and 37.3% (TCAA). Regarding TCM control, the influent TCM concentration reached as high as 80.45 μg / L. The single-bank filtration process could only achieve a low removal rate of 7.7% through weak soil adsorption. The single-nanofiltration process, leveraging the membrane's ability to retain small-molecule organic matter, increased the TCM removal rate to 25.1%. The combined process maintained its synergistic advantage, achieving a TCM removal rate of 35.4%, but its overall removal rate was still lower than that of haloacetic acid, reflecting a slightly poorer adaptability of volatile halogenated compounds to membrane retention processes. In summary, the single-bank filtration process has limited control over haloacetic acid and TCM, and is only suitable for the pretreatment of lightly polluted water. The single-nanofiltration process has a moderate removal effect, but is susceptible to membrane fouling in long-term operation. The combined bank-nanofiltration process not only achieves efficient removal of both types of pollutants but also balances treatment efficiency and system stability, with the best control effect on DCAA (41.4% removal rate of the combined process), while TCM control is relatively more difficult.

Claims

1. A device for synergistic control of disinfection byproducts and opportunistic pathogens in surface water using a low-temperature resistant shore filtration-nanofiltration combined process, characterized in that, include: Raw water tank (1), with an aeration disc (2) installed at the bottom of the raw water tank (1); The shore filter simulation column (7) is filled with multiple layers of filter media. The outlet end (3) of the raw water tank (1) is connected to the inlet (6) of the shore filter simulation column through a peristaltic pump (4). The inlet (6) of the shore filter simulation column is located above the shore filter simulation column (7). The bottom outlet of the shore filter collection tank (11) is connected to the inlet (10) of the shore filter simulation column (7); The nanofiltration membrane module (16) is connected to the outlet (12) of the shore filter water collection tank and the inlet (15) of the nanofiltration membrane module. Nanofiltration water collection tank (21), the purified water outlet of nanofiltration membrane module (16) is connected to nanofiltration water collection tank (21); Nanofiltration concentrate tank (22), the concentrate outlet (18) of the nanofiltration membrane module is connected to the nanofiltration concentrate tank (22).

2. The device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process according to claim 1, characterized in that: The number of outlets (8) of the shore filter simulation column is multiple. The multiple outlets of the shore filter simulation column are arranged at intervals along the longitudinal direction, which are used to analyze the water purification efficiency of each filter media layer of the shore filter simulation column (7) and to sample the filter media during subsequent microbial diversity analysis.

3. The device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process according to claim 1, characterized in that: A check valve (9) is provided on the pipeline between the lowest outlet of the simulated shore filter column (7) and the inlet (10) of the shore filter collection tank (11).

4. The device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process according to claim 1, characterized in that: The outlet (12) of the shore filter water collection tank is connected to the inlet (15) of the nanofiltration membrane module via a gear pump (13).

5. The device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process according to claim 4, characterized in that: The gear pump (13) is set with an inlet pressure of 0.4-0.6 MPa.

6. The device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process according to claim 1, characterized in that: A first outlet valve (19) is installed on the pipeline between the purified water outlet of the nanofiltration membrane module (16) and the nanofiltration water collection tank (21).

7. The device for synergistic control of surface water disinfection byproducts and opportunistic pathogens using a low-temperature resistant shore filtration-nanofiltration combined process according to claim 1, characterized in that: A second outlet valve (23) is installed on the pipeline between the concentrate outlet (18) of the nanofiltration membrane module and the nanofiltration concentrate tank (22).

8. The device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process according to claim 1, characterized in that: The shore filter simulation column (7) is made of UPVC / PMMA filter column with an inner diameter of 90-110mm and an effective filtration height of 50-70cm.

9. The device for synergistic control of surface water disinfection byproducts and conditionally pathogenic bacteria using a low-temperature resistant shore filtration-nanofiltration combined process according to claim 1, characterized in that: The nanofiltration membrane (17) of the nanofiltration membrane module (16) is of type NF90 / NF270, with an effective molecular weight cutoff of 90 / 270 Da.

10. A method for operating a device for synergistic control of disinfection byproducts and opportunistic pathogens in surface water using a low-temperature resistant shore filtration-nanofiltration combined process, characterized in that: An apparatus for synergistically controlling surface water disinfection byproducts and conditionally pathogenic bacteria using the low-temperature resistant shore filtration-nanofiltration combined process as described in any one of claims 1-9, comprising: Inside the raw water tank (1), the aeration disc (2) provides oxygen to the raw water. The raw water in the raw water tank (1) is pumped into the inlet (6) of the shore filter simulation column by the peristaltic pump (4). After the raw water enters the shore filter simulation column (7), it flows through each filter media layer in sequence for purification and is discharged into the shore filter water collection tank (11); The permeate from the shore filter in the shore filter collection tank (11) is purified in the nanofiltration membrane module (16) and discharged into the nanofiltration collection tank (21). At the same time, the concentrate generated during the nanofiltration process is discharged into the nanofiltration concentrate tank (22).

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