Water treatment system and polymorphic operation method thereof

Abstract

According to the water treatment system and the multi-state operation method thereof disclosed by the invention, multiple operation modes are set and are automatically switched according to water quality parameters, so that accurate response to different water quality characteristics is realized. By adopting a mode of combining residual chemical cleaning and CEB cleaning, the use cost of the chemical is reduced; the problem of water production under an extreme temperature condition is solved through strong brine backflow and expansion of a secondary reverse osmosis membrane group; and the overall recovery rate of the system is improved by dynamically adjusting the reflux quantity of the ultrafiltration backwashing wastewater. By setting detailed water quality parameter monitoring indexes and mode triggering conditions, the operation accuracy of the system is further improved. Reasonable configuration of the residual explosive cleaning device and the CEB cleaning device ensures the cleaning effect, and arrangement of the recovery rate control unit realizes continuous optimization of the operation efficiency of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and particularly relates to a water treatment system and a multi-state operation method thereof. Background Art

[0002] Water treatment plants in coastal industrial zones usually need to treat the influent from the cooling water system of power plants. The quality of this kind of influent fluctuates greatly, and the treatment difficulty is high. When facing the drastic fluctuation of water quality, the current water treatment systems often adopt fixed operation modes and cannot effectively cope with complex influent conditions.

[0003] Specifically, when the cooling water of the power plant passes through the flood discharge area of the sluice, the water quality will be affected by multiple factors.

[0004] The drastic fluctuation of water quality has a serious impact on the water treatment system. At high pollution loads, conventional cleaning methods will lead to too high chemical costs; when the water temperature is too low, the water production will be insufficient; and under high temperature conditions, the effluent water quality is difficult to meet the standards. In addition, the treatment method for ultrafiltration backwash wastewater in the prior art is fixed, which not only affects the total recovery rate of the system but also cannot ensure the stable operation of the membrane module.

[0005] Traditional water treatment systems generally have problems such as high operation costs, poor system adaptability, and unstable water production quality. Especially when dealing with complex water sources such as power plant cooling water, due to the lack of differential treatment strategies for different water quality characteristics, it is difficult to achieve the unity of economy and efficiency. Summary of the Invention

[0006] The purpose of the present invention is to provide a water treatment system and a multi-state operation method thereof to solve the technical problems of poor adaptability and high operation costs of water treatment systems in the prior art.

[0007] To solve the above technical problems, the present invention provides a multi-state operation method for a water treatment system, including the following steps:

[0008] Detect the influent water quality parameters;

[0009] According to the water quality parameters, switch the system operation mode:

[0010] When it is detected that the influent pollution degree is higher than the preset threshold, start the high-pollution working condition mode and use residual chemical cleaning for the ultrafiltration system;

[0011] When it is detected that the influent water quality is lower than the preset threshold, start the normal working condition mode and use CEB cleaning for the ultrafiltration system;

[0012] When it is detected that the influent water temperature is lower than the preset temperature threshold, start the low-temperature working condition mode and carry out concentrated brine reflux;

[0013] When the detected inlet water temperature is higher than the preset upper temperature limit, start the high-temperature working condition mode, expand the secondary reverse osmosis membrane group, and increase the water production of the secondary reverse osmosis system; and

[0014] Adjust the return flow rate of the ultrafiltration backwash wastewater according to the change of the inlet water quality.

[0015] Optionally, the water quality parameters include turbidity, temperature, conductivity, TOC content, suspended solid content, and metal element content.

[0016] Optionally, the triggering conditions for the high-pollution working condition mode are: the inlet water turbidity is higher than 150 NTU, or the TOC content is higher than 25 mg / L, or the suspended solid content is higher than 180 mg / L, or the conductivity is higher than 45 ms / cm, or the heavy metal content exceeds the surface water class III standard.

[0017] Optionally, the triggering conditions for the normal working condition mode are: the inlet water turbidity is in the range of 5 - 50 NTU, and the TOC content is lower than 15 mg / L, and the suspended solid content is lower than 100 mg / L, and the conductivity is in the range of 0.58 - 20 ms / cm.

[0018] Optionally, the triggering conditions for the low-temperature working condition mode are: the inlet water temperature is lower than 5 °C, and the conductivity is higher than 30 ms / cm.

[0019] Optionally, the triggering conditions for the high-temperature working condition mode are: the inlet water temperature is higher than 35 °C, and the conductivity is higher than 35 ms / cm.

[0020] Optionally, it further includes the step of adjusting the system recovery rate according to the change of the inlet water quality.

[0021] The present invention also provides a water treatment system for implementing the above method, including:

[0022] A water quality detection unit for detecting the inlet water quality parameters;

[0023] An ultrafiltration system including a cleaning unit for performing residual drug cleaning and CEB cleaning;

[0024] A reverse osmosis system including at least one group of expandable secondary reverse osmosis membrane groups;

[0025] A reflux control unit for controlling the reflux of the concentrated brine and the ultrafiltration backwash wastewater;

[0026] A control system for selecting an operating mode according to the water quality parameters and controlling the operation of each unit.

[0027] Optionally, the water quality detection unit includes: a turbidity sensor, a temperature sensor, a conductivity sensor, a TOC detector, a suspended solid detector, and a heavy metal detector.

[0028] Optionally, the control system includes:

[0029] a storage module for storing preset thresholds, where the preset thresholds include a turbidity threshold, a temperature threshold, a conductivity threshold, a TOC content threshold, a suspended solid content threshold, and a heavy metal content threshold; and

[0030] a processing module for selecting an operating mode according to the comparison result between the detection result and the preset threshold.

[0031] Compared with the prior art, the present invention has at least the following technical effects:

[0032] By setting multiple operating modes and automatically switching according to water quality parameters, the present invention realizes precise response to different water quality characteristics. By adopting a combination of residual drug cleaning and CEB cleaning, the cost of chemical agents is reduced; by means of concentrated brine reflux and expansion of the second-stage reverse osmosis membrane module, the problem of water production under extreme temperature conditions is solved; by dynamically adjusting the reflux amount of ultrafiltration backwash wastewater, the overall recovery rate of the system is improved.

[0033] By setting detailed water quality parameter monitoring indicators and mode trigger conditions, the present invention further improves the precision of system operation. The reasonable configuration of the residual drug cleaning and CEB cleaning devices ensures the cleaning effect, while the setting of the recovery rate control unit realizes continuous optimization of the system operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a block diagram of a multi-state operation method of a water treatment system in an embodiment of the present invention;

[0035] Figure 2 It is a schematic diagram of modules of a water treatment system in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The following is a description of a water treatment system and its multi-state operation method according to the present invention with reference to the schematic diagrams, in which the preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as a broad guidance for those skilled in the art and not as a limitation to the present invention.

[0037] In the following paragraphs, the present invention will be described more specifically by way of example with reference to the accompanying drawings. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, only for the purpose of facilitating and clearly assisting in explaining the objectives of the embodiments of the present invention.

[0038] The influent turbidity of the water treatment plant in the coastal industrial zone can fluctuate from 5 NTU to 200 NTU in a short period of time, the temperature ranges from 3 °C to 41.5 °C, and the conductivity varies drastically between 0.58 - 52 ms / cm. At the same time, the TOC content and suspended solid content in the influent also show large fluctuations, being 3 - 34.54 mg / L and 15 - 206 mg / L respectively, and the water also contains various metal elements. Therefore, the present invention provides a multi-state operation method and system for a water treatment system to achieve precise response to different water quality characteristics.

[0039] Example 1:

[0040] Please refer to Figure 1 , this example provides a multi-state operation method for a water treatment system, and its main steps are as follows:

[0041] S1: Detect influent water quality parameters

[0042] Real-time monitor the influent water quality parameters, including turbidity, temperature, conductivity, TOC content, suspended solid content, and metal element content.

[0043] In a specific example, the turbidity is detected by an online turbidimeter with a detection range of 0 - 1000 NTU; the temperature is detected by a temperature sensor with a detection range of 0 - 50 °C; the conductivity is detected by a conductivity meter with a detection range of 0 - 100 ms / cm; the TOC content is detected by a TOC analyzer; the suspended solid content is detected by an online suspended solid analyzer; the metal element content is detected by a heavy metal online analyzer.

[0044] S2: Switch the system operation mode according to the water quality parameters

[0045] The system selects the corresponding operation mode according to the detected water quality parameters:

[0046] S21: When the influent turbidity is higher than 150 NTU, or the TOC content is higher than 25 mg / L, or the suspended solid content is higher than 180 mg / L, or the conductivity is higher than 45 ms / cm, or the heavy metal content exceeds the Class III surface water standard, start the high-pollution working condition mode. In this mode, the system will use the residual medicine to clean the ultrafiltration system. Specifically: collect the residual medicine after the previous cleaning, and give priority to using these residual medicines for cleaning during the new round of cleaning, thereby reducing the chemical cost.

[0047] It should be noted that the Class III surface water standard is one of the water quality classification standards stipulated in the "Surface Water Environment Quality Standard" (GB3838 - 2002) in China. For the heavy metal content, the specific limits of the Class III standard include:

[0048] Copper content ≤ 1.0 mg / L, zinc content ≤ 1.0 mg / L, lead content ≤ 0.05 mg / L, cadmium content ≤ 0.005 mg / L, hexavalent chromium content ≤ 0.05 mg / L, arsenic content ≤ 0.05 mg / L, and mercury content ≤ 0.0001 mg / L.

[0049] S22: When the influent turbidity is in the range of 5 - 50 NTU, and the TOC content is lower than 15 mg / L, and the suspended solid content is lower than 100 mg / L, and the conductivity is in the range of 0.58 - 20 ms / cm, start the normal operating mode. In this mode, use CEB to clean the ultrafiltration system, that is, use chemical enhanced backwashing for membrane cleaning.

[0050] It should be noted that CEB refers to Chemical Enhanced Backwashing, which is a commonly used membrane cleaning method. Specifically, CEB cleaning includes the following steps:

[0051] First, perform ordinary backwashing to remove reversible pollutants on the membrane surface;

[0052] Then inject chemical agents (usually chlorine preparations, acids or alkalis) and soak for a certain period of time;

[0053] Finally, rinse with clean water until clean.

[0054] S23: When the influent temperature is lower than 5°C and the conductivity is higher than 30 ms / cm, start the low-temperature operating mode. In this mode, by returning the concentrated brine generated by the system to the influent end, use the heat in the concentrated brine to increase the influent temperature, and at the same time reduce the icing risk by increasing the influent salt content.

[0055] S24: When the influent temperature is higher than 35°C and the conductivity is higher than 35 ms / cm, start the high-temperature operating mode. In this mode, by expanding the secondary reverse osmosis membrane module, increase the treatment capacity of the secondary reverse osmosis system to ensure good desalination effect under high-temperature conditions.

[0056] Specifically, the system working process is as follows:

[0057] Startup phase:

[0058] After the system is powered on, it performs self-check, each sensor is calibrated, and it is confirmed that each actuator is in a normal state. Normal operation phase:

[0059] The water quality detection unit continuously monitors the influent parameters, the control system performs data acquisition and analysis every 10 seconds, and determines the currently applicable operating mode according to the analysis results.

[0060] Mode switching process:

[0061] (1) Switch from the normal mode to the high-pollution mode:

[0062] Gradually reduce the membrane flux to 80% of the designed flux, start the residual drug recovery system, adjust the backwashing parameters, increase the backwashing intensity, and the system completes the switch within 30 minutes.

[0063] (2) Switch from the normal mode to the low-temperature mode:

[0064] Open the concentrated brine reflux valve, adjust the reflux ratio (initially set at 15%), dynamically adjust the reflux flow according to the influent water temperature, and the system completes the switch within 15 minutes.

[0065] (3) Switch from the normal mode to the high-temperature mode:

[0066] Start the standby reverse osmosis membrane module, adjust the product water pressure and flow rate, optimize the hydraulic distribution between the membranes, and the system completes the switch within 20 minutes.

[0067] Furthermore, it also includes step S3: Dynamically adjust the return flow rate of the ultrafiltration backwash wastewater

[0068] The system adjusts the return flow rate of the ultrafiltration backwash wastewater in real time according to the change of the influent water quality.

[0069] In a specific embodiment, when the influent water quality is good, the return flow rate can be increased to improve the system recovery rate; when the influent water quality is poor, the return flow rate is correspondingly reduced to protect the membrane components.

[0070] In addition, it also includes step S4: Adjust the system recovery rate

[0071] Dynamically adjust the overall recovery rate of the system according to the change of the influent water quality and the operation status of each treatment unit.

[0072] In a specific embodiment, when the water quality is good, the system recovery rate can reach more than 40%; when the water quality is poor, the system recovery rate can be reduced to about 30%.

[0073] In another specific embodiment, the regulation of the system recovery rate follows the following principles:

[0074] (1) When the water quality is good (the following conditions are met simultaneously):

[0075] When the turbidity < 30 NTU, TOC < 10 mg / L, suspended solids < 80 mg / L, and conductivity < 15 ms / cm, gradually increase the recovery rate to 40%, and the adjustment range each time does not exceed 2%.

[0076] (2) When the water quality is average (any index exceeds the above range but does not reach the high-pollution working condition):

[0077] Maintain a recovery rate of 35%, and strengthen the monitoring of the change of the membrane pressure difference.

[0078] (3) When the water quality is poor (reaching the conditions of high pollution working conditions):

[0079] Reduce the recovery rate to 30% - 35%, increase the cleaning frequency, and gradually resume after the water quality improves.

[0080] In the embodiment of the present invention, by real - time monitoring the water quality parameters of the influent and flexibly switching the operation mode according to the water quality change, the problem of poor adaptability of the traditional water treatment system is solved. Under high - pollution working conditions, through the residual drug cleaning strategy, the chemical consumption per ton of water can be reduced by more than 30%; under normal working conditions, CEB cleaning is adopted to avoid the waste of chemicals caused by frequent chemical cleaning. The system realizes the optimization of chemical dosage while ensuring the water quality meets the standard by intelligently switching different working conditions. At the same time, under the dynamic regulation of the backwash wastewater return flow of ultrafiltration, even when the influent water quality fluctuates, the system can still operate with a high recovery rate of 30% - 40%, which not only ensures the water production efficiency but also maintains the stable operation of the membrane module. Especially when treating complex water sources such as once - through cooling water in power plants, the system shows excellent adaptability and economy.

[0081] Embodiment 2:

[0082] Please refer to Figure 1 , this embodiment provides a water treatment system for implementing the polymorphic operation method in Embodiment 1, including the following units:

[0083] The water quality detection unit is set at the water inlet end of the system, including a turbidity sensor, a temperature sensor, a conductivity sensor, a TOC detector, a suspended solid detector, and a heavy metal detector, for real - time monitoring of the influent water quality parameters.

[0084] The ultrafiltration system includes an ultrafiltration membrane module and a cleaning unit.

[0085] The cleaning unit includes a residual drug storage device and a CEB chemical storage device, which are respectively used for storing and recycling the residual cleaning chemicals and storing the chemicals for chemical enhanced backwashing.

[0086] The volume of the residual drug storage device is 1.5 times the one - time usage of the cleaning system, and the CEB chemical storage device is set with an appropriate volume according to the daily operation requirements.

[0087] The reverse osmosis system includes a first - stage reverse osmosis and an expandable second - stage reverse osmosis membrane module.

[0088] Among them, the second - stage reverse osmosis membrane module adopts a modular design, and the number of membrane modules can be flexibly increased or decreased according to needs. In the high - temperature working condition mode, the treatment capacity can be improved by increasing the number of membrane modules.

[0089] The reflux control unit includes a brine reflux pump and a wastewater reflux pump, which are respectively used to control the reflux flow rates of brine and ultrafiltration backwash wastewater.

[0090] In a specific example, the reflux pumps all adopt variable frequency control, enabling precise adjustment of the flow rate.

[0091] The control system includes a central processing unit, a storage module, and a processing module.

[0092] The storage module is used to store the preset thresholds of various water quality parameters. The processing module selects an appropriate operation mode and controls the operation parameters of each unit according to the comparison result between the real-time detection data and the preset thresholds.

[0093] The recovery rate control unit realizes the optimal control of the overall system recovery rate by adjusting the recovery rates of all links in the system.

[0094] In this embodiment, multiple functional units cooperate with each other to achieve the intelligent operation of the system. Through the comprehensive monitoring of the water quality detection unit and the intelligent judgment of the control system, the system can respond to water quality changes in a timely manner; the modular design and residual drug recovery function of the cleaning unit effectively reduce the operation cost; the scalable design of the reverse osmosis system provides room for adjusting the processing capacity; the cooperation between the reflux control unit and the recovery rate control unit ensures the efficient and stable operation of the system. The entire system has a reasonable structure, and the units cooperate tacitly with each other, significantly improving the adaptability and economy of the system while achieving water quality compliance.

[0095] A water treatment system and its multi-state operation method provided by the present invention have the following advantages:

[0096] (1) By flexibly switching between multiple operation modes, the system can adapt to different water quality conditions and ensure the stability of the effluent water quality. Especially when treating water sources with large water quality fluctuations such as power plant once-through cooling water, it shows excellent adaptability.

[0097] (2) By adopting innovative technical means such as residual drug cleaning and brine reflux, the operation cost is significantly reduced, and the economy of the system is improved. The system recovery rate can be adjusted within the range of 30% - 40% according to the water quality situation, achieving a good balance between economic benefits and treatment effects.

[0098] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A multi-state operation method for a water treatment system, characterized in that: The following steps are involved: Detect inlet water quality parameters; According to the water quality parameters, switch the system operation mode: When it is detected that the inlet water contamination level is higher than the preset threshold, the high-pollution working mode is activated and the ultrafiltration system is cleaned with residual chemicals; When it is detected that the inlet water quality is lower than the preset threshold, the normal operating mode is started and the ultrafiltration system is cleaned by CEB; When the inlet water temperature is detected to be lower than the preset temperature threshold, the low temperature working mode is started to reflux concentrated brine; When it is detected that the inlet water temperature is higher than the preset temperature upper limit, the high temperature working mode is started, the secondary reverse osmosis membrane group is expanded, and the water output of the secondary reverse osmosis system is increased; as well as Adjust the return flow rate of ultrafiltration backwash wastewater according to changes in influent water quality.

2. The method according to claim 1, characterized in that The water quality parameters include turbidity, temperature, conductivity, TOC content, suspended matter content and metal element content.

3. The method according to claim 2, characterized in that The triggering conditions of the high pollution operating mode are: the inlet turbidity is higher than 150NTU, or the TOC content is higher than 25mg / L, or the suspended matter content is higher than 180mg / L, or the conductivity is higher than 45ms / cm, or the heavy metal content exceeds the surface water Class III standard.

4. The method according to claim 2, characterized in that: The triggering conditions of the conventional operating mode are: the inlet turbidity is within the range of 5-50NTU, the TOC content is lower than 15mg / L, the suspended solids content is lower than 100mg / L, and the conductivity is within the range of 0.58-20ms / cm.

5. The method according to claim 2, characterized in that: The triggering conditions of the low temperature working mode are: the inlet water temperature is lower than 5°C and the conductivity is higher than 30ms / cm.

6. The method according to claim 2, characterized in that The triggering conditions of the high temperature working mode are: the inlet water temperature is higher than 35°C and the conductivity is higher than 35ms / cm.

7. The method according to claim 1, characterized in that Also included is the step of adjusting the system recovery rate according to changes in influent water quality.

8. A water treatment system for implementing the method according to any one of claims 1 to 7, characterized in that: include: Water quality detection unit, used to detect the inlet water quality parameters; Ultrafiltration system, including a cleaning unit for performing residual drug cleaning and CEB cleaning; A reverse osmosis system, comprising at least one expandable secondary reverse osmosis membrane group; Reflux control unit, used to control the reflux of concentrated brine and ultrafiltration backwash wastewater; The control system is used to select an operation mode according to the water quality parameters and control the operation of each unit.

9. The water treatment system according to claim 8, characterized in that: The water quality detection unit includes: a turbidity sensor, a temperature sensor, a conductivity sensor, a TOC detector, a suspended matter detector and a heavy metal detector.

10. The water treatment system according to claim 8, characterized in that: The control system comprises: a storage module for storing preset thresholds, wherein the preset thresholds include a turbidity threshold, a temperature threshold, a conductivity threshold, a TOC content threshold, a suspended matter content threshold, and a heavy metal content threshold; and A processing module for selecting an operating mode according to a comparison result between a detection result and a preset threshold value.

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