A system for preparing boiler makeup water using municipal water

Abstract

The utility model belongs to water treatment technical field discloses a kind of system for preparing boiler make-up water using municipal reclaimed water, the system includes the flocculation and precipitation equipment, filtration unit, ultrafiltration device, reverse osmosis unit, desalination equipment, concentrated water recovery unit and sludge treatment unit connected in turn.The method is through adjusting pool dynamic aeration stable water quality, using flocculation and precipitation process without auxiliary coagulant to deposit, realize water resources cascade utilization using backwash water recovery system, and realize concentrated water closed loop treatment and near zero discharge using concentrated water reverse osmosis coupling multi-effect evaporation crystallization technology.The utility model effectively solves the problems of poor adaptability to reclaimed water quality, fast membrane pollution, low resource utilization and difficult treatment of high-salt concentrated water in the prior art, and the system is stable, energy-saving and environmentally friendly, and the produced water fully meets the requirements of boiler make-up water.

Description

Technical Field

[0001] This utility model relates to the field of water treatment technology, specifically to a system for preparing boiler feedwater using urban greywater. Background Technology

[0002] With the rapid development of industry and urbanization, the problem of water shortage is becoming increasingly severe. Boiler feedwater is an important water source in industrial production, and its preparation usually consumes a large amount of high-quality water resources, resulting in high costs. Urban reclaimed water, which is non-potable water that has been treated to meet certain water quality standards, has the characteristics of stable water quantity and abundant water source. Using it as a water source for preparing boiler feedwater can effectively alleviate water shortage and reduce production costs.

[0003] However, existing methods for preparing boiler feedwater from urban greywater mostly employ conventional processes such as equalization tanks, filtration, reverse osmosis, and ion exchange, which have the following drawbacks: insufficient adaptability to fluctuations in urban greywater quality and complex pollutants, resulting in poor system operational stability; lack of effective aeration control in the equalization tank during the pretreatment stage, leading to significant difficulties in subsequent treatment when faced with sudden high COD water quality; indiscriminate addition of coagulants can easily lead to irreversible fouling of the ultrafiltration membrane, resulting in rapid membrane flux decline; backwash water and reverse osmosis concentrate from the filtration unit are not effectively utilized in a cascade manner, resulting in low water resource utilization; and the lack of a closed-loop treatment scheme for high-salinity concentrate leads to high overall system energy consumption and operating costs, making it difficult to meet the requirements of water resource recycling and zero discharge. Utility Model Content

[0004] To address the aforementioned issues, this utility model discloses a system for preparing boiler feedwater using urban greywater, which improves water quality adaptability and system stability. The backwash water and reverse osmosis concentrate from the filtration unit can be utilized in stages, meeting the requirements for water resource recycling and zero discharge.

[0005] A system for preparing boiler feedwater using urban greywater includes a pretreatment unit, a flocculation and sedimentation treatment unit, a filtration treatment unit, an ultrafiltration treatment unit, a reverse osmosis treatment unit, a desalination treatment unit, a concentrate recovery treatment unit, and a sludge treatment unit. The sludge treatment unit receives sludge generated by the flocculation and sedimentation treatment unit and the backwash water unit. The pretreatment unit includes an equalization tank, and the flocculation and sedimentation treatment unit includes a sedimentation tank. A dosing device is installed on the pipeline connecting the equalization tank and the sedimentation tank. The filtration treatment unit includes a mechanical filter and an activated carbon filter connected in sequence. The ultrafiltration treatment unit includes a filter tank, an ultrafiltration device, and... The ultrafiltration water tank; the reverse osmosis treatment unit includes a primary reverse osmosis water tank and a secondary reverse osmosis water tank connected in sequence; the outlet of the ultrafiltration water tank is connected to the primary reverse osmosis unit via an ultraviolet sterilizer; the primary reverse osmosis water tank is connected to the secondary reverse osmosis water tank via the secondary reverse osmosis unit; the secondary reverse osmosis water tank is connected to the electro-desalination equipment of the desalination treatment unit; wherein the electro-desalination equipment is connected to the desalinated water tank; the concentrate treatment unit includes a primary reverse osmosis concentrate tank, a concentrate tank, a concentrate reverse osmosis unit, and an evaporation and concentration unit; the concentrate tank collects the concentrate from the concentrate reverse osmosis unit, and the concentrate tank is connected to the evaporation and concentration unit; the evaporation and concentration unit evaporates the concentrate to crystallize it and transports it off-site.

[0006] Furthermore, the permeate from the concentrated water reverse osmosis unit is returned to the filter water tank, and the condensate from the evaporation and concentration unit is connected to the filter water tank.

[0007] Furthermore, the supernatant return port of the backwash water tank is connected to the equalization tank via a pipeline.

[0008] Furthermore, the inlet of the regulating tank is equipped with a bar screen and an aeration pipeline is installed inside the tank.

[0009] Furthermore, the sludge treatment unit includes a sludge thickening tank and a sludge dewatering machine, which dewaters the sludge to form dry sludge.

[0010] Furthermore, the dosing device includes the addition of lime slurry, polyaluminum chloride, and sodium hypochlorite.

[0011] Furthermore, the sedimentation tank is a mechanically accelerated sedimentation tank or a grid flocculation sedimentation tank.

[0012] Furthermore, the mechanical filter is a sand filter or a fiber filter.

[0013] Furthermore, the backwash water tank has a cone-shaped structure.

[0014] A method for preparing boiler feedwater using urban greywater includes the following steps: S1. Pretreatment: Urban wastewater is filtered by a screen to remove large debris and then enters a regulating tank for water quality and quantity adjustment. S2. Flocculation and sedimentation treatment: The adjusted water is sent to the sedimentation tank of the flocculation and sedimentation treatment unit for flocculation and sedimentation. Lime milk, polyaluminum chloride and sodium hypochlorite are added to the water to carry out flocculation and sedimentation reaction and disinfection is completed simultaneously. No coagulant aid is added. The generated sludge is discharged into the sludge thickening tank. S3. Filtration treatment: The water after flocculation and sedimentation is filtered through a mechanical filter and an activated carbon filter in sequence; the filtered water tank then sends the water into an ultrafiltration device and an ultrafiltration water tank for ultrafiltration treatment. The backwash water produced by the mechanical filter and activated carbon filter is discharged into the backwash water tank. After sedimentation in the backwash water tank, the clear liquid on the top layer is reused in the equalization tank. S4. After ultrafiltration effluent is sterilized by ultraviolet light and filtered by security, it enters the first-stage reverse osmosis unit and the second-stage reverse osmosis unit for deep desalination; the second-stage reverse osmosis permeate is passed into the electro-desalination equipment for final desalination, and the water in the electro-desalination equipment is stored in the desalination tank. S5. Concentrate recovery and treatment: The concentrate in the concentrate recovery tank enters the concentrate reverse osmosis unit, and the permeate is returned to the ultrafiltration permeate tank; the remaining concentrate enters the evaporation and concentration unit, the condensate is reused in the filter water tank, and the crystals are transported off-site for disposal; the concentrate produced by the first-stage reverse osmosis unit is fed into the first-stage reverse osmosis concentrate tank for treatment, and the condensate from the multi-effect evaporation and concentration unit is reused in the filter water tank. S6. Sludge treatment: The sludge in the sludge thickening tank is dewatered by a dewatering machine, and the resulting dry sludge is transported off-site for disposal.

[0015] The working principle of this invention is as follows: First, an equalization tank is introduced to regulate the water quality and quantity. Then, mechanically accelerated sedimentation tanks and grid flocculation sedimentation tanks are used to carry out flocculation and sedimentation reactions on the treated water, simultaneously completing disinfection treatment to prevent clogging in subsequent treatment stages. The treated water after flocculation and sedimentation flows sequentially through a mechanical filter and an activated carbon filter. The mechanical filter removes larger suspended solids and particulate matter through filter media interception; the activated carbon filter utilizes the adsorption properties of activated carbon to effectively remove organic matter, color, and odor from the water. The filtered water then enters an ultrafiltration device to further remove colloids, microorganisms, and large molecular organic impurities, laying the foundation for subsequent advanced treatment.

[0016] The ultrafiltration effluent enters a two-stage reverse osmosis unit for deep desalination, meeting the feed water requirements for subsequent desalination treatment. The reverse osmosis effluent then enters an electrostatic precipitator for further desalination, removing trace ions and producing desalinated water that meets the boiler feedwater quality requirements. The concentrate from the concentrate tank enters a concentrate reverse osmosis unit, and the resulting desalinated water is returned to the ultrafiltration permeate tank, achieving water resource recycling. The remaining concentrate is treated by an evaporation and concentration unit, with the evaporation condensate recycled to the filter tank. The crystals produced during concentration are treated as solid waste and disposed of by a professional organization. The beneficial effects of this utility model are: to achieve efficient utilization of urban wastewater, and to rationally treat and reuse backwash water, concentrated water and sludge generated during the treatment process, thereby reducing environmental pollution and resource waste. Attached Figure Description

[0017] Figure 1 System diagram of this utility model. Detailed Implementation

[0018] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front", "rear", "left", "right", "up" and "down" used in the following description refer to the directions in the accompanying drawings, and the terms "inner" and "outer" refer to the directions toward or away from the geometric center of a specific component, respectively.

[0019] like Figure 1 The following is a list of equipment for a system for preparing boiler feedwater using urban greywater, as described in this embodiment:

[0020]

[0021] This embodiment of a system for preparing boiler feedwater using urban greywater includes a pretreatment unit, a flocculation and sedimentation treatment unit, a filtration treatment unit, an ultrafiltration treatment unit, a reverse osmosis treatment unit, a desalination treatment unit, a concentrate recovery treatment unit, and a sludge treatment unit. The sludge treatment unit receives sludge generated by the flocculation and sedimentation treatment unit and the backwash water unit. The pretreatment unit includes an equalization tank 1, and the flocculation and sedimentation treatment unit includes a sedimentation tank 2. A dosing device is installed on the pipeline connecting the equalization tank 1 and the sedimentation tank 2. The filtration treatment unit includes a mechanical filter 5 and an activated carbon filter 6 connected in sequence. The ultrafiltration treatment unit includes a filter tank 8, an ultrafiltration device 9, and an ultrafiltration water tank 10. The reverse osmosis treatment unit includes... The primary reverse osmosis tank 13 and the secondary reverse osmosis tank 15 are connected in a secondary manner; the outlet of the ultrafiltration tank 10 is connected to the primary reverse osmosis unit 12 via an ultraviolet sterilizer 11; the primary reverse osmosis tank 13 is connected to the secondary reverse osmosis tank 15 via the secondary reverse osmosis unit 14; the secondary reverse osmosis tank 15 is connected to the electro-desalination device 16 of the desalination treatment unit; wherein the electro-desalination device 16 is connected to the desalinated water tank 17; the concentrate treatment unit includes a primary reverse osmosis concentrate tank 18, a concentrate tank 20, a concentrate reverse osmosis unit 19, and an evaporation and concentration unit 21; the concentrate tank 20 collects the concentrate from the concentrate reverse osmosis unit 19, and the concentrate tank 20 is connected to the evaporation and concentration unit 21; the evaporated crystals 22 from the evaporation and concentration unit 21 are transported externally.

[0022] The permeate from the concentrated water reverse osmosis unit 19 is returned to the filter water tank 8, and the condensate from the evaporation and concentration unit 21 is connected to the filter water tank 8; the supernatant return port of the backwash water tank 7 is connected to the regulating tank 1 through a pipeline.

[0023] The specific processing method in this embodiment is as follows: Step 1: Water Pretreatment; Urban wastewater is first introduced into equalization tank 1. A screen is installed at the inlet to intercept large debris such as plastic bags and leaves. Aeration pipes are laid inside equalization tank 1, and an online COD monitor is installed. When the COD of the influent is detected to be higher than the set value, the aeration intensity is automatically increased to enhance oxidation and mixing; when the COD is lower, the aeration intensity is reduced to save energy.

[0024] Step Two: Flocculation and Sedimentation Treatment; The adjusted water is pumped into a mechanically accelerated clarification tank, where the following reagents are precisely added via metering pumps: Lime slurry: 80 mg / L, used to adjust the pH to approximately 10.5 to promote carbonate hardness precipitation. Polyaluminum chloride (PAC): 25 mg / L, used as a flocculant to form flocs. Sodium hypochlorite: 8 mg / L, ensuring a contact time of over 30 minutes for disinfection. No coagulant aids are added in this step to prevent subsequent ultrafiltration membrane fouling; the sludge produced by flocculation and sedimentation is discharged into sludge thickening tank 3.

[0025] Step 3: Filtration and Backwash Water Recovery; The supernatant after flocculation and sedimentation sequentially enters mechanical filter 5 and activated carbon filter 6 to remove suspended solids and organic matter, respectively. Backwashing Operation: Mechanical filter 5 and activated carbon filter 6 are backwashed every 24 hours of operation or when the pressure difference reaches 0.1 MPa. Before backwashing, the accumulated water in the filters is drained through program control.

[0026] Backwash water treatment: Backwash water is collected in backwash water tank 7, which has a conical structure and is equipped with a sludge scraper. The backwash water inlet is designed with tangential vortex flow to effectively reduce disturbance to the sludge settled at the bottom of the tank. After settling, the supernatant is pumped back to equalization tank 1 for reuse, and the concentrated sludge at the bottom is periodically discharged into sludge thickening tank 3.

[0027] Step 4: Ultrafiltration Treatment; The filtered water is stored in the filter water tank 8 and then pumped into the ultrafiltration unit 9. The ultrafiltration membrane uses a hollow fiber membrane to further remove colloids, bacteria, and large molecular organic matter from the water. The backwash water from the ultrafiltration unit 9 is also discharged into the backwash water tank 7 for treatment.

[0028] Step 5: Deep desalination via reverse osmosis; the ultrafiltration permeate is stored in the ultrafiltration water tank 10, and then passes through the following in sequence: UV sterilizer 11 to kill bacteria, primary reverse osmosis unit 12, and secondary reverse osmosis unit 14. The concentrate produced by the primary reverse osmosis is discharged into the primary reverse osmosis concentrate tank 18, and the concentrate produced by the secondary reverse osmosis directly enters the concentrate tank 20.

[0029] Step Six: Final Desalination; The secondary reverse osmosis permeate enters the electrostatic precipitator (EDI) unit 16 for deep desalination. The final permeate is stored in the desalinated water tank 17 as qualified boiler feedwater.

[0030] Step 7: Closed-loop treatment of concentrate; The primary reverse osmosis concentrate in the primary reverse osmosis concentrate tank 18 is pumped into the concentrate reverse osmosis unit 19, and the fresh water produced by the concentrate reverse osmosis unit 19 is returned to the filter water tank 8 for reuse.

[0031] The concentrate from the reverse osmosis unit 19 is mixed with the concentrate from the secondary reverse osmosis unit in the concentrate tank 20 and then enters the multi-effect evaporation and concentration unit 21. The condensate produced by the multi-effect evaporation and concentration unit 21 is recycled to the filter water tank 8. The final concentrate enters the dry crystallization unit 22, and the resulting crystalline salt is entrusted to a professional organization for off-site disposal as solid waste.

[0032] Step 8: Sludge treatment. The sludge from the sedimentation tank 2 and backwash water tank 7 of the flocculation sedimentation equipment is concentrated in the sludge thickening tank 3, and then dewatered by the dewatering machine 4 to form sludge cake, which is then handed over to a qualified unit for compliant disposal.

[0033] This embodiment achieves an overall water recovery rate of over 90% by reusing backwash water and concentrated water in stages, significantly reducing the consumption of fresh water.

[0034] The technical means disclosed in this utility model are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A system for preparing boiler feedwater using urban greywater, characterized in that, The system includes a pretreatment unit, a flocculation and sedimentation treatment unit, a filtration treatment unit, an ultrafiltration treatment unit, a reverse osmosis treatment unit, a desalination treatment unit, a concentrate recovery treatment unit, and a sludge treatment unit. The sludge treatment unit receives sludge generated by the flocculation and sedimentation treatment unit and the backwash water unit. The pretreatment unit includes an equalization tank (1), and the flocculation and sedimentation treatment unit includes a sedimentation tank (2). A dosing device is provided on the pipeline connecting the equalization tank (1) and the sedimentation tank (2). The filtration treatment unit includes a mechanical filter (5) and an activated carbon filter (6) connected in sequence. The ultrafiltration treatment unit includes a filter water tank (8), an ultrafiltration device (9), and an ultrafiltration water tank (10). The reverse osmosis treatment unit includes a primary reverse osmosis water tank (13) and a secondary reverse osmosis water tank (15) connected in sequence; the outlet end of the ultrafiltration water tank (10) is connected to the primary reverse osmosis device (12) through an ultraviolet sterilizer (11); the primary reverse osmosis water tank (13) is connected to the secondary reverse osmosis water tank (15) through the secondary reverse osmosis device (14); the secondary reverse osmosis water tank (15) is connected to the electro-desalination device (16) of the desalination treatment unit; wherein the electro-desalination device (16) is connected to the desalinated water tank (17); the concentrate recovery treatment unit includes a primary reverse osmosis concentrate tank (18), a concentrate tank (20), a concentrate reverse osmosis device (19), and an evaporation and concentration device (21).

2. The system for preparing boiler feedwater using urban greywater according to claim 1, characterized in that, The concentrate tank (20) collects the concentrate from the reverse osmosis unit (19), and the concentrate tank (20) is connected to the evaporation and concentration unit (21); the evaporated crystals (22) from the evaporation and concentration unit (21) are transported out.

3. A system for preparing boiler feedwater using urban greywater according to claim 1, characterized in that, The permeate from the concentrated water reverse osmosis unit (19) is returned to the filter water tank (8), and the condensate from the evaporation and concentration unit (21) is connected to the filter water tank (8).

4. A system for preparing boiler feedwater using urban greywater according to claim 1, characterized in that, The regulating tank (1) is connected to the supernatant return port of the backwash water tank (7) via a pipeline.

5. A system for preparing boiler feedwater using urban greywater according to claim 1, characterized in that, The regulating tank (1) is equipped with a screen at the water inlet and an aeration pipeline is installed inside the tank.

6. A system for preparing boiler feedwater using urban greywater according to claim 1, characterized in that: The sludge treatment unit includes a sludge thickening tank (3) and a sludge dewatering machine (4). The sludge is dewatered by the dewatering machine to form dry sludge.

7. A system for preparing boiler feedwater using urban greywater according to claim 1, characterized in that, The dosing device includes the addition of lime slurry (2.1), polyaluminum chloride (2.2), and sodium hypochlorite (2.3).

8. A system for preparing boiler feedwater using urban greywater according to claim 1, characterized in that, The sedimentation tank (2) is a mechanically accelerated sedimentation tank or a grid flocculation sedimentation tank.

9. A system for preparing boiler feedwater using urban greywater according to claim 1, characterized in that, The mechanical filter (5) is a sand filter or a fiber filter.

10. A system for preparing boiler feedwater using urban greywater according to claim 4, characterized in that, The backwash water tank (7) has a cone-shaped structure.

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