Integrated energy-saving and water-saving water treatment system and treatment process

Abstract

The invention provides an integrated energy-saving and water-saving water treatment system and process, and relates to the field of water treatment.The integrated energy-saving and water-saving water treatment system comprises a pre-oxidation tank, a mixing unit, a flocculation tank, a high-density sedimentation tank, a filtering tank and a clean water tank which are sequentially connected in the water flow direction, the mixing unit is used for mixing chemicals and raw water, and the filtering tank is provided with an air-water backwashing device. Through the hydraulic energy potential comprehensive utilization module, efficient mixing of chemicals is achieved by adopting the hydraulic drive type micro-resistance mixer without external power, the energy recovery device is used for recovering the excess pressure of backwashing wastewater, the excess pressure is directly used for driving a water pump or a chemical adding pump, energy consumption is remarkably reduced, and energy saving and emission reduction are achieved. Meanwhile, the wastewater near-zero discharge recycling module treats and recycles the wastewater to a pretreatment or flocculation procedure through a backwashing wastewater recycling pool and a sludge concentrated solution recycling pipeline, so that the discharge is reduced, and the water utilization rate is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to an integrated energy-saving and water-saving water treatment system and process. BACKGROUND

[0002] With the advancement of urban-rural integration and the increasingly stringent environmental protection requirements, integrated water plants have been widely used in small and medium-sized water treatment scenarios due to their small footprint, short construction period, and convenient management. However, the high energy consumption and high water consumption problems exposed in the long-term operation of the existing integrated water plants have become a bottleneck restricting their further promotion.

[0003] In terms of energy consumption, the power consumption of traditional integrated water plants is mainly concentrated in the mixing of reagents and the fluid delivery link. First, conventional mechanical or pipe static mixers need to rely on external power to drive the stirrer or overcome huge water head loss, and the electrical energy consumption is continuous and considerable. Second, the backwashing process of the filter tank requires a high-pressure water pump and a fan to provide a large amount of energy, and the backwashing wastewater rich in residual pressure is usually directly discharged, and this part of energy is wasted without being effectively recovered.

[0004] In terms of water consumption, there is still a lot of room for improvement in the water production rate of the water plant itself. The traditional water plant usually directly discharges the sludge supernatant of the sedimentation tank and the backwashing wastewater of the filter tank as production wastewater. This part of water can account for 2%-5% of the total water treatment capacity of the water plant, which is a huge waste for water resource shortage areas. Although some technologies attempt to recycle wastewater, they often lack effective pretreatment and precise intelligent control, causing the pollutants carried by the recycled water to impact the front-end main process, thereby affecting the water quality and even increasing the dosage of subsequent reagents, forming a vicious cycle of water saving and increased consumption.

[0005] In summary, the existing integrated water plant has the problems of high energy consumption and high self-consumption rate in the operation process. SUMMARY

[0006] In view of the shortcomings of the prior art, the present application provides an integrated energy-saving and water-saving water treatment system and process, which aims to solve the problems of high energy consumption and high self-consumption rate of the existing integrated water plant in the operation process, and provides a system and process that can significantly reduce the operating power consumption, reagent consumption, and improve the water recovery rate while ensuring the water quality.

[0007] To achieve the above purpose, the present application realizes the following technical scheme: an integrated energy-saving and water-saving water treatment system and process, comprising a pre-oxygenation tank, a mixing unit, a flocculation tank, a high-density sedimentation tank, a filter tank and a clear water tank connected in sequence along the water flow direction, the mixing unit is used for mixing reagents and raw water, the filter tank is provided with a gas-water backwashing device, and one end of the pre-oxygenation tank 1 is connected with a water inlet main pipe 9. The processing system further comprises a hydraulic energy comprehensive utilization module, a wastewater near-zero discharge recycling module and an intelligent control module; The hydraulic energy comprehensive utilization module comprises a hydraulic drive type micro-resistance mixer arranged in the mixing unit, wherein a turbine assembly driven to rotate by the inflow water stream is arranged in the hydraulic drive type micro-resistance mixer, and the turbine assembly is linked with a mixing rotational flow sheet for realizing efficient mixing of the medicament and water without external power. An energy recovery device is installed and connected to the backwashing wastewater pipeline of the filter tank for recovering the residual pressure energy in the backwashing wastewater. The wastewater near-zero discharge recycling module comprises a backwashing wastewater recycling tank, wherein the water inlet end of the backwashing wastewater recycling tank is connected with the backwashing wastewater discharge port of the filter tank, and the water outlet end thereof is connected to the water inlet end of the pre-oxygen tank through a backflow pipeline or connected to the water inlet end of the hydraulic drive type micro-resistance mixer. A sludge concentration liquid recycling pipeline is arranged in the sludge discharge port of the high-density sedimentation tank and the water inlet end of the flocculation tank, and is used for recycling the supernatant after the sludge concentration in the sedimentation tank to the flocculation process. The intelligent control module comprises a central controller, which is connected with a flow sensor, a pressure sensor and a water quality monitoring instrument, and dynamically controls the operation state of the hydraulic drive type micro-resistance mixer based on the inflow pressure and flow of the system. The backflow time and flow of the backwashing wastewater recycling tank and the sludge concentration liquid recycling pipeline are intelligently controlled based on the inflow water quality and system load.

[0008] Preferably, the turbine assembly comprises a fixed turbine, the rotating shaft of the turbine extends and is coaxially connected with the mixing rotational flow sheet; the blade section of the turbine is in the shape of an airfoil for efficiently converting the water flow kinetic energy into rotational mechanical energy under the impact of the inflow water stream; the rotating shaft of the turbine is connected with the mixing rotational flow sheet through a gearbox, and the gearbox is used for adjusting the rotating speed of the mixing rotational flow sheet to adapt to different inflow flow and mixing intensity requirements.

[0009] Preferably, the energy recovery device is a pressure exchanger, which is connected with the dosing pump of the hydraulic drive type micro-resistance mixer, and the recovered pressure energy is directly used to drive the water pump or the dosing pump.

[0010] Preferably, the backwashing wastewater recycling tank is provided with an inclined plate sedimentation area for solid-liquid separation of the collected backwashing wastewater. The treated supernatant is backflowed to the pre-oxygen tank through the backflow pipeline.

[0011] Preferably, a sludge concentration device is connected in series on the sludge concentration liquid recycling pipeline, and the sludge concentration device is a gravity concentration tank. The sludge concentration device is used for concentrating the sludge discharged from the high-density sedimentation tank, and the overflow liquid thereof is returned to the flocculation tank as the supernatant.

[0012] Preferably, an adjusting valve and a suspended solid concentration meter are arranged on the sludge concentration liquid recycling pipeline. The central controller of the intelligent control module is in signal connection with the suspended solid concentration meter and the adjusting valve, and according to the data monitored by the suspended solid concentration meter in real time, the opening of the adjusting valve is dynamically adjusted to control the suspended solid concentration in the supernatant to be kept in a preset target range.

[0013] Preferably, the central controller of the intelligent control module predicts the pressure fluctuation period of the water supply network based on the water inlet main pressure and time information monitored by the pressure sensor. During the period when the pressure is higher than the preset high threshold, the power of the clear water delivery pump after the filter tank is reduced or stopped, and the water supply is preferentially realized by using the network pressure to realize peak-shaving energy saving.

[0014] Preferably, the central controller of the intelligent control module dynamically controls the rotating speed of the mixing cyclone vane by adjusting the gearbox of the water-driven micro-resistance mixer based on the water inlet flow monitored by the flow sensor, so that the mixing intensity is matched with the water inlet flow.

[0015] Preferably, the central controller of the intelligent control module establishes a prediction model with water inlet turbidity and water temperature as the core to estimate the flocculation effect and sludge yield of the system. Based on the estimation result, the optimal return flow of the sludge concentration liquid recycling pipeline and the trigger return turbidity threshold of the backwash wastewater recycling tank are dynamically calculated and set.

[0016] The treatment process of the integrated energy-saving and water-saving water treatment system comprises the following steps: S1, pre-oxidation and energy recovery: the raw water enters a pre-oxidation tank for pre-oxidation treatment, and the backwash wastewater generated by the filter tank is introduced into an energy recovery device to recover the residual pressure energy thereof; S2, water-driven mixing: the pre-oxidized water or raw water drives the turbine assembly in the water-driven micro-resistance mixer to rotate through the water inlet pressure, and then drives the mixing cyclone vane to rotate, so that the mixing of the medicament and water is realized without external power; S3, flocculation and sludge recycling: the mixed water enters a flocculation tank for flocculation reaction, at the same time, the sludge discharged from the high-density sedimentation tank is concentrated, and the supernatant generated by the concentration is returned to the water inlet end of the flocculation tank to strengthen the flocculation effect; S4, precipitation and filtration: the flocculated water is subjected to solid-liquid separation in a high-density precipitation tank, and the supernatant is subjected to filtration in a filtration tank; S5, wastewater reuse and intelligent control: the backwashing wastewater after energy recovery in S1 is collected to a backwashing wastewater reuse tank for sedimentation, and the supernatant thereof is backflowed to a pre-oxygen tank or a water inlet end of the hydraulically driven micro-resistance mixer; Wherein, the water inlet pressure, flow, and water quality parameters of the system are monitored in real time by the central controller, and at least one of the following controls is performed; S5.1, based on the water inlet pressure and flow, the running state of the hydraulically driven micro-resistance mixer is dynamically adjusted; S5.2, based on the water inlet water quality and system load, the backflow time and backflow amount of the sludge supernatant and backwashing wastewater are intelligently controlled; S5.3, based on the water inlet pressure prediction, the peak-shaving energy-saving operation of the clean water delivery pump is realized.

[0017] The application provides an integrated energy-saving and water-saving water treatment system and process. The application has the following beneficial effects: the application uses a hydraulically driven micro-resistance mixer to realize efficient mixing of reagents without external power supply by using a hydraulic energy potential comprehensive utilization module, and uses an energy recovery device to recover the backwashing wastewater residual pressure to directly drive a water pump or a dosing pump, thereby significantly reducing energy consumption. The wastewater near-zero discharge reuse module recovers the wastewater to a pretreatment or flocculation process after treatment through a backwashing wastewater reuse tank and a sludge concentrate reuse pipeline, thereby reducing discharge and improving water utilization rate. The intelligent control module dynamically adjusts the mixer running state, reuse time, and reuse amount based on real-time monitoring of flow, pressure, and water quality parameters, predicts pressure fluctuations to realize peak-shaving energy-saving, and ensures efficient and stable operation of the system. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a general process and module integration schematic diagram of the integrated energy-saving and water-saving water treatment system of the application.

[0019] Figure 2 It is an internal structure schematic diagram of the hydraulically driven micro-resistance mixer in the application.

[0020] Figure 3 It is a process flow schematic diagram of the hydraulically driven micro-resistance mixer in the application.

[0021] Figure 4 It is a connection and process schematic diagram of the energy recovery device and the dosing pump in the application.

[0022] Figure 5 It is a process and module integration schematic diagram of the wastewater near-zero discharge reuse module in the application.

[0023] Figure 6The system control principle block diagram of the wisdom control module of the application.

[0024] In the figure: 1, pre-oxygen pool; 2, flocculation pool; 3, high-density sedimentation tank; 4, filter tank; 5, clean water tank; 6, hydraulic drive type micro-resistance mixer; 9, water inlet main pipe; 14, energy recovery device; 15, backwashing wastewater recycling tank; 16, sludge thickening liquid recycling pipeline; 17, mixing unit; 18, turbine assembly; 19, sludge thickening device; 20, mixing cyclone vane; 101, hydraulic energy potential comprehensive utilization module; 102, wastewater near-zero discharge recycling module; 103, wisdom control module. DETAILED DESCRIPTION

[0025] The embodiment of the application provides a kind of integrated energy-saving water treatment system and process, as shown in Figures 1-6 It includes pre-oxygen pool 1, mixing unit 17, flocculation pool 2, high-density sedimentation tank 3, filter tank 4 and clean water tank 5 connected in turn along water flow direction, the mixing unit 17 is used for mixing reagent with raw water, the filter tank 4 is provided with air-water backwashing device, one end of the pre-oxygen pool 1 is connected with water inlet main pipe 9, the treatment system further includes hydraulic energy potential comprehensive utilization module 101, wastewater near-zero discharge recycling module 102 and wisdom control module 103; The hydraulic energy potential comprehensive utilization module 101 includes hydraulic drive type micro-resistance mixer 6 arranged in the mixing unit 17, the hydraulic drive type micro-resistance mixer 6 is built-in turbine assembly 18 driven by inlet water flow to rotate, the turbine assembly 18 is linked with mixing cyclone vane 20, for realizing efficient mixing of reagent and water without external power; The backwashing wastewater pipeline of the filter tank 4 is installed and connected with energy recovery device 14, for recovering residual pressure energy in backwashing wastewater; The wastewater near-zero discharge recycling module 102 includes backwashing wastewater recycling tank 15, the inlet of the backwashing wastewater recycling tank 15 is connected with the backwashing wastewater discharge port of the filter tank 4, and the outlet thereof is connected to the inlet of the pre-oxygen pool 1 through backflow pipeline, or connected to the inlet of the hydraulic drive type micro-resistance mixer 6; The sludge thickening liquid recycling pipeline 16 is arranged in the communication between the sludge discharge port of the high-density sedimentation tank 3 and the inlet of the flocculation pool 2, and is used for backflowing supernatant after sludge thickening of the sedimentation tank to flocculation process; The wisdom control module 103 includes central controller, the central controller is signal connected with flow sensor, pressure sensor and water quality monitoring instrument, based on inlet water pressure and flow of system, dynamically regulates and controls the running state of the hydraulic drive type micro-resistance mixer 6; Based on the influent water quality and system load, the backwashing wastewater reuse tank 15 and the sludge concentrate reuse pipeline 16 are intelligently controlled in terms of backflow timing and backflow volume.

[0026] Further, the turbine assembly 18 includes a fixed turbine, the rotating shaft of which extends and is coaxially connected with the mixed spiral flow piece 20; the turbine blade section is of an airfoil type, for efficiently converting water flow kinetic energy into rotational mechanical energy under the impact of the water flow; the rotating shaft of the turbine is connected with the mixed spiral flow piece 20 through a gearbox, which is used to adjust the rotating speed of the mixed spiral flow piece 20 to adapt to different water inflow and mixing intensity requirements.

[0027] Further, the energy recovery device 14 is a pressure exchanger, which is connected with the dosing pump of the hydraulically driven micro-resistance mixer 6, and the recovered pressure energy is directly used to drive the water pump or the dosing pump.

[0028] Further, the backwashing wastewater reuse tank 15 is provided with an inclined plate sedimentation zone for solid-liquid separation of the collected backwashing wastewater; The treated supernatant is backflowed to the pre-oxygen tank 1 through the backflow pipeline.

[0029] Further, the sludge concentrate reuse pipeline 16 is connected in series with a sludge concentration device 19, which is a gravity concentration tank. The sludge concentration device 19 is used to concentrate the sludge discharged from the high-density sedimentation tank 3, and the overflow liquid thereof is backflowed to the flocculation tank 2 as the supernatant.

[0030] Further, the sludge concentrate reuse pipeline 16 is provided with an adjusting valve and a suspended solids concentration meter. The central controller of the intelligent control module 103 is signal-connected with the suspended solids concentration meter and the adjusting valve, and according to the data monitored by the suspended solids concentration meter in real time, the opening degree of the adjusting valve is dynamically adjusted to control the suspended solids concentration in the backflow supernatant to be kept within a preset target range.

[0031] Further, the central controller of the intelligent control module 103 predicts the pressure fluctuation period of the water supply network based on the pressure and time information of the influent main pipe 9 monitored by the pressure sensor. During the period when the pressure is higher than the preset high threshold, the power of the clear water outflow pump after the filter tank 4 is reduced or stopped, and the network pressure is preferentially used for water supply, realizing peak-shaving energy saving.

[0032] Further, the central controller of the intelligent control module 103 dynamically controls the rotating speed of the mixing cyclone vane 20 by adjusting the gearbox of the water-driven micro-resistance mixer 6 based on the inflow monitored by the flow sensor, so that the mixing intensity matches the inflow.

[0033] Further, the central controller of the intelligent control module 103 establishes a prediction model with the core of inflow turbidity and water temperature, estimates the flocculation effect and sludge yield of the system; Based on the estimation result, the optimal return flow of the sludge concentrate recycling pipeline 16 and the trigger recycling turbidity threshold of the backwashing wastewater recycling pool 15 are dynamically calculated and set.

[0034] The treatment process of the integrated energy-saving and water-saving water treatment system includes the following steps: S1, pre-oxidation and energy recovery: raw water enters the pre-oxidation pool 1 for pre-oxidation treatment, and the backwashing wastewater generated by the filter pool 4 is introduced into the energy recovery device 14 to recover the residual pressure energy; S2, water-driven mixing: the pre-oxidized water or raw water drives the turbine assembly 18 in the water-driven micro-resistance mixer 6 to rotate through the inflow pressure, and then drives the mixing cyclone vane 20 to rotate, realizing the sufficient mixing of the medicament and water without external power; S3, flocculation and sludge recycling: the mixed water enters the flocculation pool 2 for flocculation reaction, and the sludge discharged from the high-density sedimentation pool 3 is concentrated, and the supernatant generated by the concentration is returned to the inflow end of the flocculation pool 2 to strengthen the flocculation effect; S4, sedimentation and filtration: the flocculated water is subjected to solid-liquid separation in the high-density sedimentation pool 3, and the supernatant enters the filter pool 4 for filtration; S5, wastewater recycling and intelligent control: the backwashing wastewater after energy recovery in S1 is collected to the backwashing wastewater recycling pool 15 for sedimentation, and the supernatant is returned to the pre-oxidation pool 1 or the inflow end of the water-driven micro-resistance mixer 6; The central controller monitors the inflow pressure, flow, and water quality parameters of the system in real time, and performs at least one of the following controls; S5.1, dynamically regulate the running state of the water-driven micro-resistance mixer 6 based on the inflow pressure and flow; S5.2, intelligently control the return time and return flow of the sludge supernatant and backwashing wastewater based on the inflow water quality and system load; S5.3, realize the peak-shaving energy-saving operation of the clear water delivery pump based on the inflow pressure prediction.

[0035] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. An integrated energy-saving and water-saving water treatment system, comprising a pre-oxygenation tank (1), a mixing unit (17), a flocculation tank (2), a high-density sedimentation tank (3), a filtration tank (4), and a clear water tank (5) connected sequentially along the water flow direction, wherein the mixing unit (17) is used to mix the reagent with the raw water, the filtration tank (4) is equipped with an air-water backwashing device, and one end of the pre-oxygenation tank (1) is connected to an inlet main pipe (9), characterized in that: It also includes a hydraulic energy potential comprehensive utilization module (101), a wastewater near-zero discharge and reuse module (102), and a smart control module (103). The hydraulic energy potential comprehensive utilization module (101) includes a hydraulically driven micro-resistance mixer (6) disposed in the mixing unit (17). The hydraulically driven micro-resistance mixer (6) has a turbine assembly (18) that is driven to rotate by the inlet water flow. The turbine assembly (18) is linked with the mixing swirl vane (20). The backwash wastewater pipeline of the filter tank (4) is connected to an energy recovery device (14). The near-zero wastewater discharge reuse module (102) includes a backwash wastewater reuse tank (15). The inlet of the backwash wastewater reuse tank (15) is connected to the backwash wastewater discharge port of the filter tank (4), and its outlet is connected to the inlet of the pre-oxygenation tank (1) or the inlet of the hydraulically driven micro-resistance mixer (6) through a return pipeline. The sludge discharge port of the high-density sedimentation tank (3) is connected to the water inlet of the flocculation tank (2) and is provided with a sludge concentrate recycling pipeline (16). The sludge concentrate recycling pipeline (16) is used to return the supernatant after sludge concentration in the sedimentation tank to the flocculation process. The intelligent control module (103) includes a central controller, which is connected to the flow sensor, pressure sensor and water quality monitoring instrument.

2. The integrated energy-saving and water-saving water treatment system according to claim 1, characterized in that: The turbine assembly (18) includes a fixed turbine, one end of which extends and is coaxially connected to the mixing vortex vane (20), and the turbine shaft and the mixing vortex vane (20) are connected by a gearbox.

3. The integrated energy-saving and water-saving water treatment system according to claim 1, characterized in that: The energy recovery device (14) is a pressure exchanger, which is connected to the dosing pump of the hydraulically driven micro-resistance mixer (6).

4. The integrated energy-saving and water-saving water treatment system according to claim 1, characterized in that: The backwash wastewater reuse tank (15) is equipped with an inclined plate sedimentation zone; The treated supernatant is returned to the pre-oxygenation tank (1) through a return pipeline.

5. The integrated energy-saving and water-saving water treatment system according to claim 1, characterized in that: The sludge concentrate reuse pipeline (16) is connected in series with a sludge thickening device (19). The sludge thickening device (19) is used to thicken the sludge discharged from the high-density sedimentation tank (3), and its overflow liquid is returned to the flocculation tank (2) as the supernatant.

6. The integrated energy-saving and water-saving water treatment system according to claim 1, characterized in that: The sludge concentrate reuse pipeline (16) is equipped with a regulating valve and a suspended solids concentration meter; The central controller of the intelligent control module (103) is connected to the suspended solids concentration meter and the regulating valve.

7. The integrated energy-saving and water-saving water treatment system according to claim 6, characterized in that: The central controller of the intelligent control module (103) predicts the pressure fluctuation cycle of the water supply network based on the pressure and time information of the main water inlet pipe (9) monitored by the pressure sensor. During periods when the pressure is higher than the preset high threshold, the power of the clean water export pump after the filter tank (4) is reduced or stopped, and the water supply is supplied with priority by using the pipeline pressure to achieve peak-shifting energy saving.

8. The integrated energy-saving and water-saving water treatment system according to claim 1, characterized in that: The central controller of the intelligent control module (103) dynamically controls the rotation speed of the mixing vortex vane (20) by adjusting the gearbox of the hydraulically driven micro-resistance mixer (6) based on the inlet water flow monitored by the flow sensor, so that the mixing intensity matches the inlet water flow.

9. The integrated energy-saving and water-saving water treatment system according to claim 1, characterized in that: The central controller of the intelligent control module (103) establishes a prediction model based on influent turbidity and water temperature to estimate the system flocculation effect and sludge yield. Based on the estimated results, the optimal return flow rate of the sludge concentrate reuse pipeline (16) and the trigger reuse turbidity threshold of the backwash wastewater reuse tank (15) are dynamically calculated and set.

10. A treatment process based on an integrated energy-saving and water-saving water treatment system according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Pre-oxidation and energy recovery: Raw water enters the pre-oxidation tank (1) for pre-oxidation treatment. At the same time, the backwash wastewater generated by the filter tank (4) is introduced into the energy recovery device (14) to recover its residual pressure energy. S2, Hydraulic Driven Mixing: Pre-oxidized water or raw water drives the turbine assembly (18) in the hydraulically driven micro-resistance mixer (6) to rotate through the inlet water pressure, thereby driving the mixing vortex vane (20) to rotate, so as to achieve full mixing of the reagent and water without the need for external power. S3. Flocculation and sludge reuse: The mixed water enters the flocculation tank (2) for flocculation reaction. At the same time, the sludge discharged from the high-density sedimentation tank (3) is concentrated, and the supernatant produced by concentration is returned to the inlet of the flocculation tank (2) to enhance the flocculation effect. S4. Sedimentation and filtration: The flocculated water undergoes solid-liquid separation in a high-density sedimentation tank (3), and the supernatant enters a filtration tank (4) for filtration. S5. Wastewater reuse and intelligent control: The backwash wastewater after energy recovery in S1 is collected to the backwash wastewater reuse tank (15) for sedimentation, and its supernatant is returned to the inlet of the pre-oxygenation tank (1) or the hydraulically driven micro-resistance mixer (6). The system's inlet pressure, flow rate, and water quality parameters are monitored in real time by a central controller, and at least one of the following controls is executed: S5.

1. Based on the inlet water pressure and flow rate, dynamically adjust the operating status of the hydraulically driven micro-resistance mixer (6); S5.2 Based on the influent water quality and system load, intelligently control the timing and flow rate of sludge supernatant and backwash wastewater return; S5.3 Based on inlet water pressure prediction, realize peak-shifting and energy-saving operation of clean water export pumps.

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