Reclaimed water recycling device suitable for hard and silicon-containing wastewater

Abstract

The utility model discloses a reclaimed water recycling device suitable for hard and silicon-containing wastewater, which is used for reducing hardness, silicon, organic matter content and salt content in mixed sewage and comprises a softening silicon removal unit, a COD (Chemical Oxygen Demand) removal unit and a desalting unit, the softening and silicon removal unit is used for performing efficient precipitation or high-density precipitation on the mixed sewage; the COD removal unit is used for filtering and adsorbing the mixed sewage; the desalting unit is used for performing ultrafiltration and reverse osmosis desalting on the mixed sewage; the mixed sewage is connected to the softening and silicon removal unit, an outlet of the softening and silicon removal unit is connected to the COD removal unit through a neutralization water pump, an outlet of the COD removal unit is connected to the desalting unit through an intermediate water pump, a fresh water outlet of the desalting unit is used for producing reuse water reaching the standard for reuse, and a concentrated water outlet of the desalting unit is used for discharging high-salt-content concentrated water. The hardness, the silicon content, the organic matter content and the salt content in raw water are reduced through the softening silicon removal unit, the COD removal unit and the desalting unit as well as the auxiliary configuration of the dosing unit and the chemical cleaning unit.

Description

Technical Field

[0001] The utility model relates to the technical field of sewage treatment, in particular to a device suitable for recycling reclaimed water containing hard and silicon-containing wastewater. Background Art

[0002] Industrial production generates a large amount of wastewater. Generally, this wastewater cannot be discharged directly. It must undergo biochemical, physicochemical, and other treatments to meet national or local discharge standards before it can be discharged. However, even after treatment, the wastewater still pollutes the aquatic environment. Furthermore, companies must purchase additional water for their needs, resulting in a waste of water resources. Reclaimed water reuse systems can help reduce wastewater discharge, and the continued use of recycled water in production processes can save water resources for companies.

[0003] Currently, recycled water reuse mostly uses recycled sewage as the water source, and sometimes other production wastewater is also mixed in. The mixed sewage has the characteristics of high salt content, high hardness, and silicon content. Generally, the recycled water reuse technology adopts a double membrane method, that is, ultrafiltration + reverse osmosis technology. However, the hardness, silicon, organic matter, etc. in the mixed sewage will cause the membrane surface to be blocked by dirt and affect the water flux, affecting the normal operation of the recycled water reuse ultrafiltration membrane and reverse osmosis membrane equipment.

[0004] The most common hardness removal process currently uses lime softening. Although lime is inexpensive and widely available, it is only suitable for raw water with high carbonate hardness. For raw water with low carbonate hardness, the lime-soda method is used instead. However, these methods are ineffective in removing silicon and produce a large amount of sludge, which increases the load on the sludge treatment system. The use of lime requires a complete lime dosing system to convert quicklime into lime milk. This system includes a lime silo, feeder, cavitation vibration device, air storage tank, safety valve, dust collector, screw propeller, mixing tank, storage tank, dosing pump, automatic valves, and control instrumentation. The system is complex and occupies a large area.

[0005] Organic matter removal is typically achieved through biochemical methods, but the circulating wastewater itself does not contain high levels of COD and is not biodegradable, making biochemical methods unsuitable. If a membrane bioreactor were used, the wastewater's high salt content, hardness, and alkalinity would cause severe scaling within the reactor, making it unusable in severe cases.

[0006] Since the existing technology has no targeted removal method for hardness, silicon, COD, etc. in raw sewage, the recovery rate of ultrafiltration and reverse osmosis cannot be very high, resulting in a lower recycling water recovery rate and excessive external water discharge.

[0007] Therefore, a reclaimed water reuse device suitable for hard and silicon-containing wastewater is proposed, which can remove hardness and silicon, reduce COD, and ensure the long-term stable operation of the double membrane (ultrafiltration + reverse osmosis) system. Utility Model Content

[0008] The utility model provides a reclaimed water recycling device suitable for wastewater containing hardness and silicon, which can reduce the hardness, silicon and organic matter contents in raw water.

[0009] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0010] A reclaimed water reuse device suitable for wastewater containing hardness and silicon, used to reduce the hardness, silicon and organic matter content in mixed sewage, characterized by comprising a softening and silicon removal unit, a COD removal unit, and a desalination unit;

[0011] The softening and silicon removal unit is used to perform high-efficiency sedimentation or high-density sedimentation on the mixed sewage;

[0012] The COD removal unit is used to filter and adsorb the mixed sewage;

[0013] The desalination unit is used to perform ultrafiltration and reverse osmosis desalination on the mixed sewage;

[0014] The mixed sewage is connected to the softening and desiliconizing unit, the outlet of the softening and desiliconizing unit is connected to the COD removal unit through a neutralization water pump, the outlet of the COD removal unit is connected to the desalination unit through an intermediate water pump, the fresh water outlet of the desalination unit is used to produce recycled water that meets the standards for reuse, and the concentrated water outlet of the desalination unit is used to discharge concentrated water with high salt content.

[0015] Preferably, the softening and desiliconizing unit comprises a softening reaction tank, a desiliconizing reaction tank, a coagulation tank, a flocculation tank, a high-efficiency sedimentation tank and a neutralization tank connected in sequence;

[0016] The mixed sewage is connected to the inlet of the softening reaction tank, alkali and softener are added to the softening reaction tank, desiliconizer is added to the desiliconization reaction tank, coagulant is added to the coagulation tank, flocculant is added to the flocculation tank, and acid is added to the neutralization tank;

[0017] The COD removal unit includes a multi-media filter, an activated carbon adsorber, and an intermediate water tank connected in sequence;

[0018] The neutralization tank is connected to the multi-media filter via a neutralization water pump. The multi-media filter is filled with anthracite and various graded quartz sand filter media to filter suspended solids in the sewage. The activated carbon adsorber is filled with coconut shell activated carbon filter media to absorb organic matter in the sewage. Oxidants are added to the intermediate water tank to control microbial contamination and store transitional effluent.

[0019] The desalination unit includes a self-cleaning filter, an ultrafiltration membrane assembly, an ultrafiltration water tank, an ultrafiltration water pump, a safety filter, a reverse osmosis high-pressure pump and a reverse osmosis membrane assembly connected in sequence;

[0020] The intermediate water tank is connected to the self-cleaning filter through the intermediate water pump, and the self-cleaning filter is used to remove impurities with a particle size greater than 100 μm in the mixed sewage; the outlet of the self-cleaning filter is connected to the ultrafiltration membrane assembly, and the ultrafiltration membrane in the ultrafiltration membrane assembly adopts a PVDF hollow fiber membrane, which is used to filter and intercept pollutants such as colloids, proteins, microorganisms and large molecular organic matter in the mixed sewage; the water produced at the outlet of the ultrafiltration membrane assembly is connected to the ultrafiltration water tank, and the ultrafiltration water tank is connected to the security filter through the ultrafiltration water pump; a microporous filter element is installed in the security filter to filter tiny particle impurities greater than 5 μm in the mixed sewage; the reverse osmosis membrane assembly is drawn into the security filter by a reverse osmosis high-pressure pump, one outlet of the reverse osmosis membrane assembly is used to discharge fresh water, and the other outlet of the reverse osmosis membrane assembly is used to discharge high-salt concentrated water;

[0021] The inlet of the ultrafiltration membrane assembly is connected to the ultrafiltration water tank through a backwash pipeline using an ultrafiltration backwash pump, which is used to draw water into the ultrafiltration membrane assembly for intermittent timed backwashing. The backwash water enters the membrane filaments from the water production side of the ultrafiltration membrane assembly, and the reverse water flow flushes the pollutants attached to the surface of the membrane filaments out of the ultrafiltration membrane assembly.

[0022] Preferably, the fresh water outlet of the reverse osmosis membrane assembly is connected to the reverse osmosis membrane assembly through a reuse water tank using a flushing water pump for backwashing; the concentrated water outlet of the reverse osmosis membrane assembly is used for discharge.

[0023] Preferably, the COD removal unit further comprises a backwash water pump, the inlet of the backwash water pump being connected to the intermediate water tank, and the outlet of the backwash water pump being connected to the multi-media filter and the activated carbon adsorber, for backwashing out the suspended matter trapped by the filter media in the multi-media filter and the activated carbon adsorber.

[0024] Preferably, the COD removal unit further comprises a fan connected to the multi-media filter and the activated carbon adsorber, for providing air to loosen the filter media in the multi-media filter and the activated carbon adsorber, thereby improving the backwash effect of the backwash water pump.

[0025] Preferably, it further comprises a chemical cleaning unit, wherein the chemical cleaning unit comprises a chemical cleaning tank and a chemical cleaning pump;

[0026] The ultrafiltration membrane assembly and the reverse osmosis membrane assembly are connected through two pipelines to form a back-and-forth drug circulation pipeline;

[0027] The outlet of the chemical cleaning tank is connected to the inlet of the chemical cleaning pump. The water in the chemical cleaning tank is pressurized by the chemical cleaning pump and then flows through a drug circulation pipeline into the chemical cleaning inlet of the ultrafiltration membrane assembly or the reverse osmosis membrane assembly.

[0028] The chemical cleaning outlet on another drug circulation pipeline connected to the ultrafiltration membrane assembly or reverse osmosis membrane assembly through the cleaning pipeline is refluxed into the chemical cleaning tank, so that the circulating cleaning agent dissolves and discharges the contaminants on the surface of the ultrafiltration membrane filament or reverse osmosis membrane to restore the membrane flux.

[0029] Preferably, the chemical cleaning unit further comprises a cleaning filter.

[0030] The chemical cleaning pump outlet is connected to the cleaning filter, and the reagent is connected to the chemical cleaning inlet of the ultrafiltration membrane assembly or the reverse osmosis membrane assembly through the cleaning pipeline after being filtered by the cleaning filter.

[0031] Preferably, it further comprises a dosing unit, which includes an alkali dosing device, a softener dosing device, a silicon removal agent dosing device, a coagulant dosing device and a flocculant dosing device;

[0032] Alkali is added into the softening reaction tank through the alkali dosing device to adjust the pH value of the influent to alkaline; softener is added into the softening reaction tank through the softener dosing device to reduce the hardness in the water; desiliconizer is added into the desiliconization reaction tank through the desiliconizer dosing device to reduce the silicon content in the water; coagulant is added into the coagulation tank through the coagulant dosing device to form small flocs by precipitation; flocculant is added into the flocculation tank through the flocculant dosing device to form large flocs by small flocs; acid is added into the neutralization tank through the acid dosing device to adjust the pH value of the effluent to neutral.

[0033] Preferably, the dosing unit further comprises an acid dosing device, an oxidant dosing device, a reductant dosing device, an antiscalant dosing device and a non-oxidizing bactericide dosing device;

[0034] Acid, alkali and oxidant are respectively added to the backwash pipeline of the ultrafiltration membrane assembly through an acid dosing device, an oxidant dosing device and an alkali dosing device to increase the backwash effect;

[0035] Oxidant is added into the intermediate water tank through the oxidant dosing device to control microbial contamination of the intermediate water tank; scale inhibitor is added to the water inlet pipe of the reverse osmosis membrane assembly through the reductant dosing device, scale inhibitor dosing device and non-oxidizing bactericide dosing device to control fouling on the concentrated water side, reductant is added to ensure that the reverse osmosis membrane is not damaged by oxidation, and non-oxidizing bactericide is added to regularly control membrane biological contamination.

[0036] Preferably, the softening and silicon removal unit, COD removal unit, desalination unit, dosing unit, and chemical cleaning unit are all centrally controlled via signal connection to a DSC or PLC.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] This utility model effectively reduces the hardness, silicon, and organic matter content in raw water through a softening and silicon removal unit, a COD removal unit, and a desalination unit, supplemented by a dosing unit and a chemical cleaning unit. The softening and silicon removal unit utilizes high-efficiency precipitation or high-density precipitation technology, the COD removal unit utilizes a multi-media filter and activated carbon adsorption technology, and the desalination unit utilizes dual-membrane treatment technology for ultrafiltration and reverse osmosis. The softening and silicon removal unit incorporates softening and silicon removal reactions to address the high hardness and silicon content of industrial wastewater. Combined with high-efficiency precipitation or high-density precipitation technology, it effectively reduces the hardness and silicon content of the raw water. The entire facility boasts a compact structure and stable operation. The COD removal unit further reduces the organic matter content in the raw water, while the activated carbon adsorption technology provides excellent adsorption and fully automatic operation. Compared to existing technologies that are prone to scaling, have low water production rates, and unstable effluent quality, this utility model specifically reduces the hardness, silicon, and COD content in the raw water. This reduces the inlet water to the desalination unit from fouling and clogging, resulting in stable ultrafiltration and reverse osmosis operation, improved recovery rates, increased recycled water output, and reduced brine volume. The entire system occupies a small area, has stable operation and a high degree of automation. It is suitable for the reuse and treatment of reclaimed water containing hard and silicon wastewater, achieving the goal of energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of the working principle of a reclaimed water recycling device suitable for hard and silicon-containing wastewater proposed in an embodiment of the present utility model;

[0040] Figure 2 This is a water balance diagram of a reclaimed water reuse device suitable for hard and silicon-containing wastewater proposed in an embodiment of the present utility model.

[0041] The numbers in the figure are as follows:

[0042] 1. Softening and silicon removal unit; 1-1. Softening reaction tank; 1-2. Derailment reaction tank; 1-3. Coagulation tank; 1-4. Flocculation tank; 1-5. High-efficiency sedimentation tank; 1-6. Neutralization tank; 2. COD removal unit; 2-1. Multi-media filter; 2-2. Activated carbon adsorber; 2-3. Intermediate water tank; 3. Desalination unit; 3-1. Self-cleaning filter; 3-2. Ultrafiltration membrane assembly; 3-3. Ultrafiltration water tank; 3-4. Ultrafiltration water pump; 3-5. Security filter; 3-6. Reverse osmosis high-pressure pump; 3-7. Reverse osmosis membrane assembly; 3-8. Recycled water tank; 3-9 , flushing water pump; 3-10, ultrafiltration backwash pump; 4, dosing unit; 4-1, alkali dosing device; 4-2, softener dosing device; 4-3, desiliconizer dosing device; 4-4, coagulant dosing device; 4-5, flocculant dosing device; 4-6, acid dosing device; 4-7, oxidant dosing device; 4-8, reducing agent dosing device; 4-9, scale inhibitor dosing device; 4-10, bactericide dosing device; 5, chemical cleaning unit; 5-1, chemical cleaning tank; 5-2, chemical cleaning pump; 5-3, cleaning filter; 6, neutralization water pump; 7, intermediate water pump. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0044] like Figure 1 As shown, the utility model provides a reclaimed water reuse device suitable for hard and silicon-containing wastewater, which is used to reduce the hardness, silicon and organic matter content in mixed wastewater, including a softening and silicon removal unit 1, a COD removal unit 2, a desalination unit 3, a dosing unit 4 and a chemical cleaning unit 5.

[0045] The mixed sewage is connected to the softening and desiliconizing unit 1, the outlet of the softening and desiliconizing unit 1 is connected to the COD removal unit 2 through the neutralization water pump 6, the outlet of the COD removal unit 2 is connected to the desalination unit 3 through the intermediate water pump 7, the fresh water outlet of the desalination unit 3 is used to produce recycled water that meets the standards for reuse, and the concentrated water outlet of the desalination unit 3 is used to discharge concentrated water with high salt content.

[0046] Softening and silicon removal unit 1 uses high-efficiency precipitation or high-density precipitation technology to perform high-efficiency precipitation or high-density precipitation on mixed sewage. Softening and silicon removal unit 1 includes a softening reaction tank 1-1, a silicon removal reaction tank 1-2, a coagulation tank 1-3, a flocculation tank 1-4, a high-efficiency sedimentation tank 1-5, and a neutralization tank 1-6, which are connected in sequence. The mixed sewage is connected to the inlet of softening reaction tank 1-1. Alkali and softening agent are added to softening reaction tank 1-1 to adjust the pH value of the influent to alkaline and to reduce the hardness of the water. Silicon removal reaction tank 1-2 is added with a silicon removal agent to reduce the silicon content in the water. Coagulant is added to coagulation tank 1-3 to precipitate the mixed sewage into small flocs. Flocculant is added to flocculation tank 1-4 to transform small flocs into large flocs. Acid is added to neutralization tank 1-6 to adjust the pH value of the effluent. Softening and silicon removal unit 1 is equipped with softening reaction and silicon removal reaction in view of the high hardness and silicon content of industrial wastewater. Combined with high-efficiency precipitation or high-density precipitation technology, it effectively reduces the hardness and silicon content of raw water. The whole set of facilities has a compact structure and stable operation.

[0047] COD Removal Unit 2 utilizes a multi-media filter and activated carbon adsorption technology to filter and adsorb mixed wastewater. It comprises a multi-media filter 2-1, an activated carbon adsorber 2-2, an intermediate water tank 2-3, and a backwash pump, all connected in sequence. COD Removal Unit 2 further reduces the organic matter content in the raw water. The activated carbon adsorption technology provides effective adsorption and operates fully automatically.

[0048] The neutralization tank 1-6 is connected to the multi-media filter 2-1 through the neutralization water pump 6. The multi-media filter 2-1 is filled with anthracite and various graded quartz sand filter materials for filtering suspended matter in the sewage; the activated carbon adsorber 2-2 is equipped with an automatic valve to automatically control the water production and backwashing process of the activated carbon adsorber 2-2. The activated carbon adsorber 2-2 is filled with coconut shell activated carbon filter material for adsorbing organic matter in the sewage; an oxidant is added to the intermediate water tank 2-3 to control microbial contamination and store transitional effluent.

[0049] The backwash pump inlet is connected to the intermediate water tank 2-3, and the backwash pump outlet is connected to the multi-media filter 2-1 and the activated carbon adsorber 2-2. The backwash pump draws water from the intermediate water tank 2-3 and connects it to the multi-media filter 2-1 and the activated carbon adsorber 2-2. A large flow of backwash water enters the bottom of the multi-media filter and the activated carbon adsorber and is discharged from the top, backwashing and removing suspended solids trapped in the filter media. The multi-media filter is equipped with an automatic valve that automatically controls the multi-media filter to produce water and perform backwashing. Furthermore, in this embodiment, the COD removal unit 2 also includes a fan, which is connected to the multi-media filter 2-1 and the activated carbon adsorber 2-2 and is used to provide air to loosen the filter media in the multi-media filter and the activated carbon adsorber, thereby improving the backwash effect of the backwash pump.

[0050] Furthermore, in this embodiment, the multi-media filter is generally steel-lined with rubber, filled with various graded quartz sand filter media and anthracite, with an upper water distributor on the top and a steel plate-mounted dual-speed water cap at the bottom. It adopts a lower operating flow rate of 8 to 10 m / h. After a certain period of operation, when the inlet and outlet pressure difference reaches a certain value or the operating flow rate reaches, it is withdrawn from use and backwashed. The filter is designed with an air scrubbing interface to enhance the backwash effect.

[0051] The activated carbon adsorber is generally made of steel lined with rubber and filled with coconut shell activated carbon filter material. The filter material residence time is generally 30 minutes. After running for a certain period of time, when the inlet and outlet pressure difference reaches a certain value or the operating flow reaches a certain value, it will be shut down for backwashing.

[0052] Desalination unit 3 utilizes dual-membrane ultrafiltration and reverse osmosis technology to treat mixed wastewater. It comprises a self-cleaning filter 3-1, an ultrafiltration membrane assembly 3-2, an ultrafiltration water tank 3-3, an ultrafiltration water pump 3-4, a safety filter 3-5, a reverse osmosis high-pressure pump 3-6, and a reverse osmosis membrane assembly 3-7, all connected in sequence. Because pretreatment specifically reduces the hardness, silica, and COD content in the raw water, the desalination unit's inlet water is less susceptible to fouling and clogging. This ensures stable ultrafiltration and reverse osmosis operation, improving recovery rates, increasing the amount of recycled water, and reducing the amount of brine.

[0053] The intermediate water tank 2-3 is connected to the self-cleaning filter 3-1 through the intermediate water pump 7. The self-cleaning filter 3-1 is used to remove impurities with a particle size greater than 100 μm in the mixed sewage; the outlet of the self-cleaning filter 3-1 is connected to the ultrafiltration membrane assembly 3-2. The ultrafiltration membrane assembly 3-2 is equipped with an automatic valve to automatically control the ultrafiltration membrane assembly to produce water and backwash, maintain online chemical enhanced backwash, and restore chemical cleaning processes. The ultrafiltration membrane in the ultrafiltration membrane assembly 3-2 adopts PVDF hollow fiber membrane, which is used to filter and intercept pollutants such as colloids, proteins, microorganisms and macromolecular organic matter in the mixed sewage; the water produced at the outlet of the ultrafiltration membrane assembly 3-2 is connected to the ultrafiltration water tank 3-3, and the ultrafiltration water tank 3-3 takes water through the ultrafiltration water pump 3-4 and connects it to the security filter 3-5; a microporous filter element is installed in the security filter 3-5, which is used to filter tiny particulate impurities larger than 5μm in the mixed sewage; the security filter 3-5 is drawn into the reverse osmosis membrane assembly 3-7 through the reverse osmosis high-pressure pump 3-6, and one outlet of the reverse osmosis membrane assembly 3-7 is used to discharge fresh water, and the other outlet of the reverse osmosis membrane assembly 3-7 is used to discharge high-salt concentrated water.

[0054] The inlet of the ultrafiltration membrane assembly 3-2 is connected to the ultrafiltration water tank 3-3 through the backwash pipeline using the ultrafiltration backwash pump 3-10, which is used to take water into the ultrafiltration membrane assembly 3-2 for intermittent timed backwashing. The backwash water enters the membrane fiber from the water production side of the ultrafiltration membrane assembly 3-2, and the reverse water flow washes the pollutants attached to the surface of the membrane fiber out of the ultrafiltration membrane assembly 3-2.

[0055] Furthermore, in this embodiment, the ultrafiltration membrane of ultrafiltration membrane assembly 3-2 is designed to have a net flux of less than 45 LMH. The ultrafiltration membrane elements are made of PVDF, which is resistant to fouling, hydrophilic, and oxidation. The filtration method is external pressure, and the membrane elements are arranged in a vertical parallel configuration. The ultrafiltration unit typically operates for 30-40 minutes, using a cycle of operation-air wash-water wash-operation. The backwash of the ultrafiltration unit uses its own produced water, and the backwash air is compressed air.

[0056] The water flux of the ultrafiltration membrane assembly 3-2 is related to the pressure difference across it. The greater the pressure difference, the greater the water output, the worse the effluent, and the faster the membrane becomes contaminated. To avoid this phenomenon caused by pressure differences during operation, a flow control valve is installed at the inlet of each ultrafiltration unit to ensure constant output.

[0057] In this embodiment, the reverse osmosis membrane assembly 3-7 generally adopts a pollution-resistant membrane element. The reverse osmosis membrane of the reverse osmosis membrane assembly 3-7 is installed in a pressure vessel, and the pressure vessel is organically combined on a steel bracket through pipes, pipe fittings and valves, as well as necessary detection instruments.

[0058] The reverse osmosis membrane assembly 3-7 is equipped with a series of control valves on the system's inlet, product, and brine pipelines. These valves automatically control the production, flushing, and chemical cleaning processes of the reverse osmosis membrane assembly 3-7. Monitoring instruments and a programmable operating system ensure the long-term, systematic operation of the equipment with guaranteed quality and quantity. The reverse osmosis membrane is a scroll-type polyamide composite membrane. The fresh water outlet of the reverse osmosis membrane assembly 3-7 is connected to the reverse osmosis membrane assembly 3-7 via a reuse water tank 3-8 and a flushing water pump 3-9 for backwashing. The brine outlet of the reverse osmosis membrane assembly 3-7 is used for discharge. The fresh water outlet of the reverse osmosis membrane assembly 3-7 is connected to the reverse osmosis membrane assembly 3-7 via a reuse water tank 3-8 and a flushing water pump 3-9 for backwashing. The brine outlet of the desalination unit 3 is used to discharge high-salinity brine.

[0059] In this embodiment, the recovery rate of the ultrafiltration membrane assembly 3 - 2 of the desalination unit 3 can reach 95%, and the recovery rate of the reverse osmosis membrane assembly 3 - 7 can reach 75%.

[0060] Chemical cleaning unit 5 includes a chemical cleaning tank 5-1, a chemical cleaning pump 5-2, and a cleaning filter 5-3. The ultrafiltration membrane assembly 3-2 and the reverse osmosis membrane assembly 3-7 are connected via two pipelines, forming a back-and-forth drug circulation line. The outlet of the chemical cleaning tank 5-1 is connected to the inlet of the chemical cleaning pump 5-2, which in turn is connected to the cleaning filter 5-3. After the drug is filtered through the cleaning filter 5-3, it is connected via a cleaning pipeline to the chemical cleaning inlet of the ultrafiltration membrane assembly 3-2 or the reverse osmosis membrane assembly 3-7.

[0061] The water in the chemical cleaning tank 5-1 is pressurized by the chemical cleaning pump 5-2 and then connected to the chemical cleaning inlet of the ultrafiltration membrane assembly 3-2 or the reverse osmosis membrane assembly 3-7 through a drug feeding circulation pipeline; the water is returned to the chemical cleaning tank 5-1 through the chemical cleaning outlet on another drug feeding circulation pipeline connected to the ultrafiltration membrane assembly 3-2 or the reverse osmosis membrane assembly 3-7 through the cleaning pipeline, so that the circulating cleaning agent dissolves and discharges the contaminants on the surface of the ultrafiltration membrane filaments or reverse osmosis membrane to restore the membrane flux.

[0062] Furthermore, in this embodiment, the chemical cleaning unit 5 also includes a cleaning filter 3-5, the outlet of the chemical cleaning pump 5-2 is connected to the inlet of the cleaning filter 3-5, a microporous filter element is installed in the cleaning filter 3-5, and the agent is filtered through the cleaning filter 3-5 and connected to the chemical cleaning inlet of the ultrafiltration membrane assembly 3-1 or the reverse osmosis membrane assembly 3-7 through the cleaning pipeline.

[0063] The dosing unit 4 includes an alkali dosing device 4-1, a softener dosing device 4-2, a desiliconizing agent dosing device 4-3, a coagulant dosing device 4-4, a flocculant dosing device 4-5, an acid dosing device 4-6, an oxidant dosing device 4-7, a reducing agent dosing device 4-8, a scale inhibitor dosing device 4-9 and a non-oxidizing bactericide dosing device 4-10.

[0064] Alkali is added to the softening reaction tank 1-1 through the alkali dosing device 4-1 to adjust the pH value of the influent to alkaline; softener is added to the softening reaction tank 1-1 through the softener dosing device 4-2 to reduce the hardness in the water; desiliconizer is added to the desiliconizer reaction tank 1-2 through the desiliconizer dosing device 4-3 to reduce the silicon content in the water; coagulant is added to the coagulation tank 1-3 through the coagulant dosing device 4-4 to form small flocs by precipitation; flocculant is added to the flocculation tank 1-4 through the flocculant dosing device 4-5 to form large flocs from small flocs; acid is added to the neutralization tank 1-6 through the acid dosing device 4-6 to adjust the pH value of the effluent to neutral; oxidant is added to the intermediate water tank 2-3 through the oxidant dosing device 4-7 to control microbial contamination in the intermediate water tank 2-3.

[0065] Acid, alkali and oxidant are added to the backwash pipeline of the ultrafiltration membrane assembly 3-2 through the acid dosing device 4-6, the oxidant dosing device 4-7 and the alkali dosing device 4-1 respectively to increase the backwash effect.

[0066] Through the reducing agent dosing device 4-8, the scale inhibitor dosing device 4-9 and the non-oxidizing bactericide dosing device 4-10, the scale inhibitor is added to the water inlet pipe of the reverse osmosis membrane assembly 3-7 to control the fouling on the concentrated water side, the reducing agent is added to ensure that the reverse osmosis membrane is not damaged by oxidation, and the non-oxidizing bactericide is added to regularly control the membrane biological fouling.

[0067] The alkali dosing device 4-1 adds at least one of sodium hydroxide and potassium hydroxide, the softener dosing device adds at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate, the desiliconizer dosing device adds at least one of magnesium oxide, magnesium chloride, and magnesium sulfate, the coagulant dosing device adds at least one of polyaluminum chloride, aluminum sulfate, sodium metaaluminate, and aluminum chloride, the flocculant dosing device adds polyacrylamide (PAM), the acid dosing device adds hydrochloric acid or sulfuric acid, the oxidant dosing device adds sodium hypochlorite, the reducing agent dosing device adds sodium bisulfite, the scale inhibitor dosing device adds at least one of polyacrylate scale inhibitor or reverse osmosis scale inhibitor, and the non-oxidizing bactericide dosing device adds isothiazolinone.

[0068] Furthermore, in this embodiment, the raw materials of the alkali dosing device 4-1, the coagulant dosing device 4-4, the acid dosing device 4-6, the oxidant dosing device 4-7, the reducing agent dosing device 4-8, the scale inhibitor dosing device 4-9, and the non-oxidizing bactericide dosing device 4-10 are in liquid state, the dosing device is equipped with a dissolving tank and a dosing pump, the chemicals are transported through pipelines or manually added regularly, the dissolving tank is equipped with a stirrer, the dissolving tank outlet is connected to the dosing pump inlet, and the chemical liquid is added to the dosing point through the dosing pump.

[0069] The raw material state of the softener dosing device 4-2, the desiliconizing agent dosing device 4-3, and the flocculant dosing device 4-5 is solid powder. The dosing device is equipped with an integrated dissolving and preparing triple box and a dosing pump. The triple box includes a hopper, a discharge machine, a mixing tank, a dissolving tank, a storage tank, a mixing mixer, a dissolving mixer, etc. The outlet of the triple box is connected to the dosing pump, and the liquid medicine is added to the dosing point through the dosing pump.

[0070] Furthermore, in this embodiment, the softening and silicon removal unit 1, the COD removal unit 2, the desalination unit 3, the dosing unit 4, and the chemical cleaning unit 5 are all centrally controlled via signal connections to a DSC or a PLC.

[0071] The following is a description based on specific data

[0072] Example 1

[0073] This embodiment provides a reclaimed water reuse device suitable for hard and silicon-containing wastewater. The device uses circulating water sewage as raw water, and mixes pretreated production sewage and washing sewage discharged from the production device. After the mixed sewage is treated by this project, it is used as circulating cooling water make-up water.

[0074] The designed inlet water quality is as follows:

[0075] Serial number Test items Index value 1 pH 6-9 2 COD ≤120mg / L 3 SS ≤100mg / L 4 Conductivity ≤4000μS / cm 5 <![CDATA[Calcium hardness (calculated as Ca 2+ count)]]> ≤120mg / L 6 <![CDATA[Total hardness (calculated as CaCO3)]]> ≤500mg / L 7 <![CDATA[SiO2]]> ≤35mg / L

[0076] The designed recycled water quality is as follows:

[0077]

[0078]

[0079] After metering from the raw water regulating tank, wastewater first enters the softening and desiliconization reaction tanks of the softening and desiliconization units via existing lift pumps. Sodium hydroxide and soda ash are added to the softening reaction tank, and MgCl2 is added to the desiliconization reaction tank, causing the carbonate hardness in the wastewater to react with silica to form a precipitate. The wastewater then enters the high-efficiency sedimentation tank, where coagulants and flocculants are added to form flocs before flowing into the inclined plate sedimentation zone. Within the inclined plate sedimentation zone, the flocculent precipitate settles to the bottom of the zone under the action of gravity. The effluent enters the neutralization tank, where hydrochloric acid is added to adjust the pH. The sludge at the bottom of the sedimentation tank is pumped by the residual sludge pump to the sludge dewatering unit for treatment. After softening, the effluent meets requirements for total hardness ≤ 100 mg / L, suspended solids ≤ 20 mg / L, pH 7.0-8.0, and SiO2 ≤ 15 mg / L. The effluent is pumped through a lift pump to the multi-media filter in the COD removal unit. The multi-media filter media further removes suspended solids from the wastewater, resulting in effluent suspended solids ≤10mg / L after treatment. The treated effluent enters the activated carbon adsorption tower, which utilizes the activated carbon's superior adsorption capacity to remove COD, surfactants, and other substances from the wastewater. After treatment with the activated carbon adsorption unit, the effluent COD is ≤60mg / L, and the surfactants are ≤3mg / L. After treatment, the effluent enters the desalination unit's self-cleaning filter, which removes fine particles larger than 100μm, suspended solids, colloids, and other impurities. The effluent then enters the desalination unit's ultrafiltration membrane assembly, which utilizes externally pressurized PVDF ultrafiltration elements with a filtration accuracy of ≤30nm and a net flux of ≤45LMH. Driven by pressure, this further removes macromolecular soluble substances, reducing the effluent turbidity to ≤0.5NTU and the SDI (Soil Dispersant Index) to ≤3. After treatment by the nano-ultrafiltration membrane assembly, the effluent enters the ultrafiltration tank. A lift pump then feeds the wastewater to the safety filter, which intercepts particles larger than 5μm carried by the raw water to prevent them from entering the desalination unit and damaging the reverse osmosis membrane. After treatment by the safety filter, the effluent enters the desalination unit's reverse osmosis membrane assembly under the action of a high-pressure pump. Desalination utilizes reverse osmosis technology, using reverse osmosis membranes to remove the vast majority of soluble salts, colloids, organic matter, and microorganisms from the water. After treatment by the desalination unit, the effluent meets the required water quality. After treatment by the desalination unit, the effluent enters the reuse water tank and is pumped by a lift pump to the circulating cooling water makeup system for reuse.

[0080] The sludge generated by the softening and silicon removal unit in the water reuse system of this embodiment can be processed in a separate sludge dewatering device. The backwash water from the multi-media filter, activated carbon adsorption tower, ultrafiltration membrane module backwash and rinse water, and reverse osmosis membrane module rinse water all enter the wastewater tank and are then transported to the raw water regulating tank via a wastewater lift pump. The brine from the reverse osmosis membrane module is transported to a brine collection tank and discharged after passing testing.

[0081] like Figure 2As shown in the figure, it is the water balance of the water reuse device in this embodiment. It can be seen that after using this water reuse device, 100m 3 / h of wastewater, after treatment, only 24m 3 / h of wastewater, the overall recovery rate of the system can reach 73%, which greatly reduces the wastewater discharge. The recycled water is transported to the circulating cooling water replenishment system, saving water costs.

[0082] At the same time, the entire system of this embodiment occupies a small area, has stable operation, and a high degree of automation, and is suitable for the reuse and treatment of reclaimed water containing hard and silicon-containing wastewater, thereby achieving the purpose of energy conservation and emission reduction.

[0083] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0084] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0085] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the present invention can make equivalent replacements or changes based on the technical solution and utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A reclaimed water recycling device suitable for wastewater containing hardness and silicon, used to reduce the hardness, silicon and organic matter content in mixed sewage, characterized by: It includes a softening and silicon removal unit (1), a COD removal unit (2), and a desalination unit (3); The softening and silicon removal unit (1) is used to perform high-efficiency sedimentation or high-density sedimentation on the mixed sewage; The COD removal unit (2) is used to filter and adsorb the mixed sewage; The desalination unit (3) is used to perform ultrafiltration and reverse osmosis desalination on the mixed sewage; The mixed sewage is connected to the softening and desiliconizing unit (1), the outlet of the softening and desiliconizing unit (1) is connected to the COD removal unit (2) via a neutralizing water pump (6), the outlet of the COD removal unit (2) is connected to the desalination unit (3) via an intermediate water pump (7), the fresh water outlet of the desalination unit (3) is used to produce recycled water that meets the standards for reuse, and the concentrated water outlet of the desalination unit (3) is used to discharge concentrated water with high salt content; The softening and silicon removal unit (1) comprises a softening reaction tank (1-1), a silicon removal reaction tank (1-2), a coagulation tank (1-3), a flocculation tank (1-4), a high-efficiency sedimentation tank (1-5) and a neutralization tank (1-6) which are connected in sequence; The mixed sewage is connected to the inlet of the softening reaction tank (1-1), alkali and softener are added to the softening reaction tank (1-1), desiliconizer is added to the desiliconization reaction tank (1-2), coagulant is added to the coagulation tank (1-3), flocculant is added to the flocculation tank (1-4), and acid is added to the neutralization tank (1-6); The COD removal unit (2) comprises a multi-media filter (2-1), an activated carbon adsorber (2-2), and an intermediate water tank (2-3) connected in sequence; The neutralization tank (1-6) is connected to the multi-media filter (2-1) via a neutralization water pump (6). The multi-media filter (2-1) is filled with anthracite and various graded quartz sand filter materials for filtering suspended solids in sewage. The activated carbon adsorber (2-2) is filled with coconut shell activated carbon filter materials for adsorbing organic matter in sewage. An oxidant is added to the intermediate water tank (2-3) for controlling microbial contamination and storing transitional effluent. The desalination unit (3) comprises a self-cleaning filter (3-1), an ultrafiltration membrane assembly (3-2), an ultrafiltration water tank (3-3), an ultrafiltration water pump (3-4), a security filter (3-5), a reverse osmosis high-pressure pump (3-6) and a reverse osmosis membrane assembly (3-7) which are connected in sequence; The intermediate water tank (2-3) is connected to a self-cleaning filter (3-1) via an intermediate water pump (7). The self-cleaning filter (3-1) is used to remove impurities with a particle size greater than 100 μm in the mixed sewage. The outlet of the self-cleaning filter (3-1) is connected to the ultrafiltration membrane assembly (3-2). The ultrafiltration membrane in the ultrafiltration membrane assembly (3-2) adopts a PVDF hollow fiber membrane and is used to filter and intercept colloids, proteins, microorganisms and macromolecular organic pollutants in the mixed sewage. The water produced at the outlet of the ultrafiltration membrane assembly (3-2) is connected to the ultrafiltration water tank. (3-3), the ultrafiltration water tank (3-3) draws water through the ultrafiltration water pump (3-4) and connects it to the security filter (3-5); the security filter (3-5) is equipped with a microporous filter element for filtering tiny particles larger than 5 μm in the mixed sewage; the security filter (3-5) draws water into the reverse osmosis membrane assembly (3-7) through the reverse osmosis high-pressure pump (3-6), one outlet of the reverse osmosis membrane assembly (3-7) is used to discharge fresh water, and the other outlet of the reverse osmosis membrane assembly (3-7) is used to discharge high-salt concentrated water; The inlet of the ultrafiltration membrane assembly (3-2) is connected to the ultrafiltration water tank (3-3) through a backwash pipeline using an ultrafiltration backwash pump (3-10), which is used to draw water into the ultrafiltration membrane assembly (3-2) for intermittent timed backwashing. The backwash water enters the membrane fibers from the water production side of the ultrafiltration membrane assembly (3-2), and the reverse water flow washes the pollutants attached to the surface of the membrane fibers out of the ultrafiltration membrane assembly (3-2).

2. A reclaimed water recycling device suitable for hard and silicon-containing wastewater according to claim 1, characterized in that: The fresh water outlet of the reverse osmosis membrane assembly (3-7) is connected to the reverse osmosis membrane assembly (3-7) through a recycling water tank (3-8) using a flushing water pump (3-9) for backwashing; the concentrated water outlet of the reverse osmosis membrane assembly (3-7) is used for discharge.

3. The reclaimed water recycling device suitable for hard and silicon-containing wastewater according to claim 1, characterized in that: The COD removal unit (2) further comprises a backwash water pump, the inlet of the backwash water pump being connected to the intermediate water tank (2-3), and the outlet of the backwash water pump being connected to the multi-media filter (2-1) and the activated carbon adsorber (2-2), for backwashing and removing suspended matter trapped by the filter media in the multi-media filter (2-1) and the activated carbon adsorber (2-2).

4. A reclaimed water recycling device suitable for hard and silicon-containing wastewater according to claim 3, characterized in that: The COD removal unit (2) further comprises a fan connected to the multi-media filter (2-1) and the activated carbon adsorber (2-2) and used for providing air to loosen the filter materials in the multi-media filter and the activated carbon adsorber, thereby improving the backwashing effect of the backwash water pump.

5. The reclaimed water recycling device suitable for hard and silicon-containing wastewater according to claim 1, characterized in that: It also includes a chemical cleaning unit (5), which includes a chemical cleaning tank (5-1) and a chemical cleaning pump (5-2); The ultrafiltration membrane assembly (3-2) and the reverse osmosis membrane assembly (3-7) are connected via two pipelines to form a back-and-forth drug circulation pipeline; The outlet of the chemical cleaning tank (5-1) is connected to the inlet of the chemical cleaning pump (5-2); the water in the chemical cleaning tank (5-1) is pressurized by the chemical cleaning pump (5-2) and then flows through a drug feeding circulation pipeline into the chemical cleaning inlet of the ultrafiltration membrane assembly (3-2) or the reverse osmosis membrane assembly (3-7); The chemical cleaning outlet on another drug circulation pipeline connected to the ultrafiltration membrane assembly (3-2) or the reverse osmosis membrane assembly (3-7) is refluxed into the chemical cleaning tank (5-1), so that the circulating cleaning agent dissolves and discharges the contaminants on the surface of the ultrafiltration membrane filaments or the reverse osmosis membrane to restore the membrane flux.

6. A reclaimed water recycling device suitable for hard and silicon-containing wastewater according to claim 5, characterized in that: The chemical cleaning unit (5) further comprises a cleaning filter (5-3), the outlet of the chemical cleaning pump (5-2) is connected to the cleaning filter (5-3), and the reagent is filtered through the cleaning filter (5-3) and then connected to the chemical cleaning inlet of the ultrafiltration membrane assembly (3-2) or the reverse osmosis membrane assembly (3-7) through a cleaning pipeline.

7. The reclaimed water recycling device for hard and silicon-containing wastewater according to claim 5, characterized in that: The invention also includes a dosing unit (4), wherein the dosing unit (4) includes an alkali dosing device (4-1), a softener dosing device (4-2), a silicon removal agent dosing device (4-3), a coagulant dosing device (4-4) and a flocculant dosing device (4-5); Alkali is added to the softening reaction tank (1-1) through the alkali dosing device (4-1) to adjust the pH value of the influent to alkaline; softener is added to the softening reaction tank (1-1) through the softener dosing device (4-2) to reduce the hardness of the water; desiliconizer is added to the desiliconizer reaction tank (1-2) through the desiliconizer dosing device (4-3) to reduce the silicon content in the water; coagulant is added to the coagulation tank (1-3) through the coagulant dosing device (4-4) to form small flocs by precipitation; flocculant is added to the flocculation tank (1-4) through the flocculant dosing device (4-5) to form large flocs by small flocs; acid is added to the neutralization tank (1-6) through the acid dosing device (4-6) to adjust the pH value of the effluent to neutral.

8. The reclaimed water recycling device for hard and silicon-containing wastewater according to claim 7, characterized in that: The dosing unit (4) further includes an acid dosing device (4-6), an oxidant dosing device (4-7), a reducing agent dosing device (4-8), an antiscalant dosing device (4-9) and a non-oxidizing bactericide dosing device (4-10); Acid, alkali and oxidant are respectively added to the backwash pipeline of the ultrafiltration membrane assembly (3-2) through an acid dosing device (4-6), an oxidant dosing device (4-7) and an alkali dosing device (4-1) to increase the backwash effect; An oxidant is added to the intermediate water tank (2-3) through an oxidant dosing device (4-7) to control microbial contamination of the intermediate water tank (2-3); an antiscalant is added to the water inlet pipe of the reverse osmosis membrane assembly (3-7) through a reducing agent dosing device (4-8), an antiscalant dosing device (4-9) and a non-oxidizing bactericide dosing device (4-10) to control fouling on the concentrated water side, a reducing agent is added to ensure that the reverse osmosis membrane is not damaged by oxidation, and a non-oxidizing bactericide is added to regularly control membrane biofouling.

9. The reclaimed water recycling device for hard and silicon-containing wastewater according to claim 8, characterized in that: The softening and silicon removal unit (1), COD removal unit (2), desalination unit (3), dosing unit (4), and chemical cleaning unit (5) are all centrally controlled via signal connection to a DSC or PLC.

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