System for resourceful treatment of sulfate wastewater

Abstract

The utility model discloses a sulfate wastewater resourceful treatment system, including oil film removal pretreatment device, ion membrane dialysis device, positive osmosis concentration device, extraction device, first evaporation crystallization device and second evaporation crystallization device, sulfate raw wastewater is in proper order through oil film removal pretreatment device, ion membrane dialysis device, and the dirty brackish water that the ion membrane dialysis device produces is connected the positive osmosis concentration device through pipeline, and the dirty concentrated brine that the positive osmosis concentration device produces is connected extraction device through pipeline, and the concentrated brine that extraction device produces is connected second evaporation crystallization device through pipeline, and the net concentrated brine that the ion membrane dialysis device produces is connected first evaporation crystallization device through pipeline. The utility model discloses low energy consumption, and the processing cost is low, and simple operation can be resourceful utilization.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment, and in particular to a resource-based treatment system for sulfate wastewater. Background Technology

[0002] Sulfate wastewater includes post-soaping liquid (such as sodium sulfate), circulating mother liquor (sodium sulfate), and ammonium sulfate wastewater, all of which require treatment.

[0003] like Figure 1 As shown, the current treatment process for sodium sulfate wastewater has the following parameters: 3200 t / d, high salinity near saturation, COD 3000~6000ppm, and total oil >200ppm which needs to be treated to <15ppm. The treatment process is as follows: the raw sodium sulfate wastewater enters the oil removal pretreatment, and then evaporates. Evaporation produces sodium sulfate crystals and condensate. The condensate enters the Fenton unit and is then discharged.

[0004] like Figure 2 As shown, the current treatment process for ammonium sulfate wastewater has the following parameters: 4000t / d, high salinity, COD 2000ppm, and total oil 1000ppm, which need to be treated to <15ppm. The treatment process is as follows: the raw ammonium sulfate wastewater enters the oil removal pretreatment, and then undergoes evaporation. Evaporation produces ammonium sulfate crystals and condensate. The condensate then enters the reverse osmosis concentration unit, and the produced water is discharged to the pure water production unit or to the sewage treatment plant for ammonia nitrogen removal before being discharged.

[0005] Current requirements for sulfate wastewater include a non-chemically emulsified oil content of <15ppm and COD compliance with discharge standards or reuse. However, existing evaporation and other processes are difficult to meet these requirements. Furthermore, it is necessary to reduce the overall treatment cost of existing evaporation processes. However, existing processes suffer from high energy consumption, high hazardous waste treatment costs, and complex operation and maintenance. Utility Model Content

[0006] To overcome the above-mentioned shortcomings, the purpose of this utility model is to provide a sulfate wastewater resource treatment system that is low in energy consumption, low in processing cost, simple to operate, and can be utilized as a resource.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a sulfate wastewater resource utilization treatment system, comprising an oil removal membrane pretreatment device, an ion-exchange membrane dialysis device, a forward osmosis concentration device, an extraction device, a first evaporation crystallization device, and a second evaporation crystallization device; the raw sulfate wastewater sequentially passes through the oil removal membrane pretreatment device and the ion-exchange membrane dialysis device; the dirty brine produced by the ion-exchange membrane dialysis device is connected to the forward osmosis concentration device via a pipeline; the dirty concentrated brine produced by the forward osmosis concentration device is connected to the extraction device via a pipeline; the concentrated brine produced by the extraction device is connected to the second evaporation crystallization device via a pipeline; and the purified concentrated brine produced by the ion-exchange membrane dialysis device is connected to the first evaporation crystallization device via a pipeline.

[0008] The beneficial effects of this utility model are: by combining oil removal film pretreatment, ion membrane dialysis, forward osmosis concentration, extraction and evaporation crystallization, it can remove non-chemically emulsified oil with a content of <15ppm and achieve COD compliance for discharge or reuse. The sodium sulfate crystals from the first and second evaporation crystallization devices can be used for resource recovery, reducing the overall treatment cost of existing evaporation processes. It has the advantages of low energy consumption, low hazardous waste treatment cost and simple operation and maintenance.

[0009] Preferably, the sulfate wastewater is ammonium sulfate wastewater or sodium sulfate wastewater.

[0010] Preferably, the oil removal membrane pretreatment device employs a superhydrophilic oil-separating membrane. The oil removal membrane pretreatment device is used to efficiently separate oily impurities (such as lubricating oil and residual grease from processes) from wastewater, avoiding serious interference with subsequent desalination processes (such as ion-exchange membrane dialysis and evaporation crystallization) (e.g., contaminating the ion-exchange membrane, affecting crystallization purity). Specifically, due to its superhydrophilic properties (contact angle < 5°), the membrane surface can be quickly wetted by the aqueous phase (an aqueous solution containing ammonium sulfate / sodium sulfate) to form a water film, preventing the oil phase (contact angle > 120°) from adhering or permeating, achieving highly efficient oil-water separation (oil removal rate can reach over 95%). Ions such as NH⁺, Na⁺, and SO₄²⁻ in the aqueous phase can permeate through the membrane with the water without being retained by the membrane, avoiding salt loss and ensuring the purity of raw materials for subsequent desalination processes.

[0011] Preferably, the superhydrophilic oil-separating membrane is one of polyimide superhydrophilic oil-separating membrane, polyethersulfone-based superhydrophilic nanofiber membrane, and titanium dioxide-based superhydrophilic oil-separating membrane. Polyimide superhydrophilic oil separators contain rigid aromatic rings and imide bonds in their polyimide molecular chains, exhibiting extremely high chemical stability. They can withstand long-term immersion in high concentrations of ammonium sulfate (5%-20%) and sodium sulfate (10%-30%), and also show good tolerance to the slightly acidic (pH 5-6) ammonium sulfate wastewater and the neutral / weakly alkaline (pH 6-8) sodium sulfate wastewater. Polyethersulfone-based superhydrophilic nanofiber membranes utilize polyethersulfone (PES), a commonly used membrane material resistant to acids, alkalis, and salts. After being fabricated into nanofiber membranes (fiber diameter 50-500 nm) using nanospinning technology and modified to be superhydrophilic, their porous structure combined with superhydrophilic properties provides significant advantages in the treatment of high-salt and oily wastewater. Titanium dioxide-based superhydrophilic separators are extremely corrosion-resistant, photocatalytically self-cleaning, and have a long lifespan, making them suitable for extreme or long-term operating environments.

[0012] Preferably, the forward osmosis concentration unit is equipped with a main permeate pipeline, on which a conductivity sensor is installed. The outlet of the main permeate pipeline is connected to two branch permeate pipelines, each of which is equipped with a valve. When one of the two valves is open and the other is closed, the conductivity sensor determines which branch permeate pipeline is being discharged from.

[0013] Preferably, one of the branch permeate pipelines is connected to the ion-exchange membrane dialysis unit; the other branch permeate pipeline is connected to a pure water production unit. When the conductivity sensor detects that the conductivity of the liquid in the main permeate pipeline is <10 μS / cm (close to the pure water level), it can directly meet the inlet water requirements of the pure water production system and directly flow into the pure water production unit through the branch permeate pipeline; when the conductivity sensor detects that the permeate conductivity of the liquid in the main permeate pipeline is >10 μS / cm, the valve on the branch permeate pipeline corresponding to the ion-exchange membrane dialysis unit is opened, and the valve on the other branch permeate pipeline is closed, allowing the permeate to enter the ion-exchange membrane dialysis system for further desalination and salt concentration of the wastewater.

[0014] Preferably, the ion-exchange membrane material of the ion-exchange membrane dialysis device is either a homogeneous cation exchange membrane or a perfluorosulfonic acid type cation exchange membrane. The homogeneous cation exchange membrane uses a styrene-divinylbenzene copolymer as its backbone, introducing cation exchange groups such as sulfonic acid groups (-SO3H) to form a uniform polymer network structure. It exhibits good chemical stability, resistance to sulfate corrosion (able to withstand high concentrations of SO4²⁻), high ion selectivity (preferentially permeating monovalent cations NH4⁺ and Na⁺), and moderate mechanical strength. The perfluorosulfonic acid type cation exchange membrane, with a perfluorocarbon backbone (extremely chemically inert) and side chains connecting sulfonic acid groups, possesses corrosion resistance, temperature resistance (withstanding 80-100℃), and swelling resistance far exceeding that of ordinary homogeneous membranes. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the existing sodium sulfate wastewater treatment process; Figure 2 This is a schematic diagram of the existing ammonium sulfate wastewater treatment process; Figure 3 This is a schematic diagram of the sodium sulfate wastewater treatment process in this embodiment; Figure 4 This is a schematic diagram of the sodium sulfate wastewater treatment process in this embodiment; Figure 5 This is a schematic diagram of the water produced by the forward osmosis concentration device in this embodiment.

[0016] Attached Figure

[0017] 1. Oil film pretreatment device; 2. Ion membrane dialysis device; 3. Forward osmosis concentration device; 4. Extraction device; 5. Second evaporation crystallization device; 6. First evaporation crystallization device; 7. Pure water production equipment; 8. Conductivity sensor; 9. Valves; 10. Main product water pipeline; 11. Branch product water pipeline. Detailed Implementation

[0018] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the scope of protection of the present invention.

[0019] See Figure 3 , Figure 4 , Figure 5 As shown, this embodiment discloses a sulfate wastewater resource utilization system, including an oil removal membrane pretreatment device 1, an ion-exchange membrane dialysis device 2, a forward osmosis concentration device 3, an extraction device 4, a first evaporation crystallization device 6, and a second evaporation crystallization device 5. The raw sulfate wastewater sequentially passes through the oil removal membrane pretreatment device 1 and the ion-exchange membrane dialysis device 2. The dirty brine produced by the ion-exchange membrane dialysis device 2 is connected to the forward osmosis concentration device 3 through a pipeline. The dirty concentrated brine produced by the forward osmosis concentration device 3 is connected to the extraction device 4 through a pipeline. The concentrated brine produced by the extraction device 4 is connected to the second evaporation crystallization device 5 through a pipeline. The clean concentrated brine produced by the ion-exchange membrane dialysis device 2 is connected to the first evaporation crystallization device 6 through a pipeline.

[0020] In this embodiment, the sulfate wastewater is either ammonium sulfate wastewater or sodium sulfate wastewater.

[0021] In this embodiment, the oil film pretreatment device 1 uses a superhydrophilic oil separator. The superhydrophilic oil separator is one of the following: polyimide superhydrophilic oil separator, polyethersulfone-based superhydrophilic nanofiber membrane, or titanium dioxide-based superhydrophilic oil separator. The specific choice depends on the requirements.

[0022] like Figure 5 As shown, the forward osmosis concentration unit 3 is equipped with a main permeate pipeline 10, on which a conductivity sensor 8 is installed. The outlet of the main permeate pipeline 10 is connected to two branch permeate pipelines 11, each with a valve 9. When one valve 9 is open and the other is closed, the conductivity sensor 8 determines which branch permeate pipeline 11 is discharging the permeate. One branch permeate pipeline 11 is connected to the ion-exchange membrane dialysis unit 2; the other branch permeate pipeline 11 is connected to the pure water production unit 7. When the conductivity sensor 8 detects that the conductivity of the liquid in the main product water pipeline 10 is <10 μS / cm, which is close to the pure water level, it can directly meet the inlet water requirements of the pure water system and is directly connected to the pure water equipment 7 through the branch product water pipeline 11; when the conductivity sensor 8 detects that the conductivity of the product water in the main product water pipeline 10 is >10 μS / cm, the valve 9 on the branch product water pipeline 11 corresponding to the ion membrane dialysis device 2 is opened, and the valve 9 on the other branch product water pipeline is closed, and the product water enters the ion membrane dialysis system for desalination and salt concentration of wastewater again.

[0023] In this embodiment, the ion-exchange membrane material of the ion-exchange membrane dialysis device 2 is either a homogeneous cation exchange membrane or a perfluorosulfonic acid type cation exchange membrane.

[0024] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it. They cannot be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the protection scope of this utility model.

Claims

1. A sulfate wastewater resource utilization treatment system, characterized in that: It includes an oil removal film pretreatment device (1), an ion membrane dialysis device (2), a forward osmosis concentration device (3), an extraction device (4), a first evaporation crystallization device (6), and a second evaporation crystallization device (5). The sulfate wastewater passes through an oil removal membrane pretreatment device (1) and an ion-exchange membrane dialysis device (2) in sequence. The dirty brine produced by the ion-exchange membrane dialysis device (2) is connected to the forward osmosis concentration device (3) through a pipeline. The dirty concentrated brine produced by the forward osmosis concentration device (3) is connected to the extraction device (4) through a pipeline. The concentrated brine produced by the extraction device (4) is connected to the second evaporation crystallization device (5) through a pipeline. The clean concentrated brine produced by the ion-exchange membrane dialysis device (2) is connected to the first evaporation crystallization device (6) through a pipeline.

2. The sulfate wastewater resource utilization treatment system according to claim 1, characterized in that: The sulfate wastewater is either ammonium sulfate wastewater or sodium sulfate wastewater.

3. The sulfate wastewater resource recovery system according to claim 2, characterized in that: The oil removal film pretreatment device (1) uses a superhydrophilic oil separator film.

4. The sulfate wastewater resource recovery system according to claim 3, characterized in that: The superhydrophilic oil separator is one of the following: polyimide superhydrophilic oil separator, polyethersulfone-based superhydrophilic nanofiber membrane, and titanium dioxide-based superhydrophilic oil separator.

5. The sulfate wastewater resource recovery system according to claim 2, characterized in that: The forward osmosis concentration device (3) is equipped with a main permeate pipeline (10), and a conductivity sensor (8) is installed on the main permeate pipeline (10). The outlet of the main permeate pipeline (10) is connected to two branch permeate pipelines (11), and each branch permeate pipeline (11) is equipped with a valve (9). When one of the two valves (9) is open, the other is closed.

6. The sulfate wastewater resource recovery system according to claim 5, characterized in that: One of the branch water pipelines (11) is connected to the ion-exchange membrane dialysis unit (2). Another branch water production pipeline (11) is connected to a pure water production equipment (7).

7. The sulfate wastewater resource recovery system according to claim 2, characterized in that: The ion membrane material of the ion membrane dialysis device (2) is either a homogeneous cation exchange membrane or a perfluorosulfonic acid type cation exchange membrane.

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