Advanced sewage treatment system

Abstract

The utility model belongs to an advanced sewage treatment system, and particularly relates to an advanced sewage treatment system which is characterized in that at least two reverse osmosis devices are arranged in parallel, and a flushing device for flushing the reverse osmosis devices is arranged and is communicated with the reverse osmosis devices through flushing pipelines; a water inlet pump is arranged on the water inlet pipeline of each reverse osmosis device, a flushing water pump is arranged on the flushing pipeline, a water pressure sensor and a water flow sensor are further arranged on each reverse osmosis device, and the water inlet pumps, the flushing water pumps, the water flow sensors and the water pressure sensors are all controlled by a main controller. The reverse osmosis device is flushed according to the operation condition of the reverse osmosis device, the reverse osmosis device is alternately replaced in the flushing process, the sewage treatment process is not influenced, and the reverse osmosis device can be recycled by combining concentrated water backflow of the reverse osmosis device and optimization of a filter medium layer. And the problem of low sewage treatment efficiency caused by the influence of microorganism attachment on the reverse osmosis device is solved.

Description

Technical Field

[0001] The utility model belongs to the field of advanced sewage treatment systems, and particularly relates to an advanced sewage treatment system. Background Art

[0002] The sewage discharged from the plant circulating water refers to the part of the water in the circulating water system that is polluted or has deteriorated in quality after use during industrial production, and needs to be discharged and fresh water needs to be replenished to maintain the normal operation of the circulating water system. These discharged sewage usually contains various pollutants, such as organic matter, suspended solids, microorganisms, dissolved salts, etc. If directly discharged without treatment, it will cause serious pollution to the environment.

[0003] In order to rationally use water and save water, improve the utilization rate of water resources, it is advocated to adopt the circulating water reuse technology to reuse the treated discharged sewage in the production process again, thereby reducing the consumption of fresh water and the sewage discharge volume. This not only helps to save water resources, but also reduces the operating costs of enterprises, and is of great significance for environmental protection and promoting sustainable development.

[0004] Currently, for the advanced treatment of the sewage discharged from the plant circulating water, it is usually carried out in sequence of coagulation, filtration, ultrafiltration, nanofiltration, and reverse osmosis treatment. For example, a method for treating and reusing the sewage discharged from the circulating water disclosed in the Chinese invention patent application CN113087197 A, the sewage discharged from the circulating water first undergoes coagulation filtration, then resin is used to remove hardness, and finally it undergoes two-step filtration by a precision filter and NF (nanofiltration). At this time, most of the sulfate ions contained in the filtered water are removed, and only monovalent ions such as chloride ions are not removed. Then, this kind of produced water is sent to before the first-stage RO of the demineralized water station and undergoes a series of processes such as reverse osmosis in the demineralized water station. The obtained water can not only serve as high-quality makeup water for the demineralized water station, but also change the configuration of the demineralized water station.

[0005] However, in the actual operation process, as the treatment time prolongs, the water outlet efficiency is greatly reduced. Summary of the Utility Model

[0006] The purpose of the utility model is to provide an advanced sewage treatment system, especially for the advanced treatment of the sewage discharged from the plant circulating water, with stable equipment operation and high water outlet efficiency.

[0007] The utility model adopts the following technical scheme:

[0008] A advanced wastewater treatment system includes a pretreatment device, a multi - filtration device, an ultra - filtration device, a security filtration device, a reverse osmosis device and a purified water collection device which are connected in sequence through pipelines. At least two reverse osmosis devices are arranged in parallel, and a flushing device for flushing the reverse osmosis devices is provided. The flushing device is connected to the reverse osmosis devices through flushing pipelines, and an inlet water pump is arranged on the inlet water pipeline of each reverse osmosis device. A flushing water pump is arranged on the flushing pipeline. A water pressure sensor for detecting the water pressure on the inlet side of the reverse osmosis device and a water flow sensor for detecting the water flow rate of the purified water side are also arranged on the reverse osmosis device. The inlet water pump, the flushing water pump, the water flow sensor and the water pressure sensor are all controlled by a main controller.

[0009] During the actual operation process, with the extension of the treatment time, the water output efficiency is greatly reduced. Mainly because in the circulating cooling water blowdown, the original water has a high COD of 150mg / L. After membrane treatment for concentration and separation, all the pollutants will be reflected in the final concentrated water. The COD of the membrane treatment system during operation will reach 500 - 600mg / L, and the total TDS will reach more than 20,000mg / L, which will cause very serious pollution to the membrane (mainly organic colloid pollution, inorganic salt scaling, and microbial growth), and the operation risk of the system is relatively high. Among these factors, microbial pollution is the most serious. Microorganisms accumulate at the membrane - water interface, thus affecting the system performance. The inside of the membrane module is humid and dark, which is an ideal environment for microbial growth. Therefore, once the biological activity level of the raw water is relatively high, biological pollution of the membrane is very likely to occur. The biological pollution of the membrane is divided into two stages: adhesion and growth. The adhered cells will grow and reproduce under the supply of inlet nutrients to form a biofilm. Secondary adhesion or entrainment on the primary biofilm further develops the biofilm. The aged biofilm bacteria are mainly decomposed into proteins, nucleic acids, polysaccharide esters and other macromolecular substances, which strongly adsorb on the membrane surface and cause surface modification of the membrane. The modified membrane surface is more likely to attract other types of microorganisms. An important characteristic of microorganisms is their ability to rapidly make biochemical and genetic adjustments to changing nutrient, hydrodynamic or other conditions. Therefore, the biological pollution of the reverse osmosis membrane elements will seriously affect the system performance, rapidly increase the pressure difference between the inlet water and the concentrated water, cause the "telescope" phenomenon and mechanical damage of the membrane elements, and reduce the water production of the membrane.

[0010] In the above solution of the present utility model, to solve this problem, starting from the most direct and most effective direction, the reverse osmosis device is flushed. By monitoring the water pressure on the water inlet side of the reverse osmosis membrane element and the water flow rate on the purified water outlet side, and through the main controller, according to the feedback water pressure and water flow rate, it is controlled whether the reverse osmosis device is flushed or not. For example, when it is detected that the water pressure on the water inlet side is large while the water flow rate on the purified water outlet side is small, it indicates that the reverse osmosis device is severely blocked and needs to be flushed. At this time, the main controller controls the water inlet pump of the reverse osmosis device to close, stops the reverse osmosis operation, and at the same time turns on the flushing pump of the flushing device to start flushing. After flushing is completed, the main controller controls the water inlet pump of the reverse osmosis device to open, and the flushing pump of the flushing device to close, and starts the reverse osmosis operation. In order not to affect the sewage treatment process during the flushing process, more than two reverse osmosis devices are provided and operate alternately. If no situation requiring flushing is detected in the reverse osmosis devices, multiple reverse osmosis devices can carry out the reverse osmosis operation simultaneously, or can be turned on according to the situation.

[0011] Preferably, a part of the concentrated water outlet end of the reverse osmosis device is communicated to the water inlet pipe of the reverse osmosis device through a reflux pipeline. Using a part of the concentrated water outlet of the reverse osmosis device to backflush the reverse osmosis device, adopting a concentrated water circulation operation mode, increasing the water flow rate on the membrane surface, slowing down the accumulation of pollutants on the membrane surface, and effectively preventing microbial pollution and inorganic pollution.

[0012] Preferably, a booster pump is provided on the reflux pipeline.

[0013] Preferably, the flushing device is communicated with the purified water collection device. Using the treated purified water to flush the reverse osmosis device, saving water.

[0014] Preferably, a second-stage reverse osmosis device is further provided downstream of the reverse osmosis device.

[0015] Preferably, the reverse osmosis device adopts the Dow FILMTEC™ Fortilize™ CR100 reverse osmosis membrane element. This reverse osmosis membrane element is a spiral wound composite membrane, with the ability to resist bacterial adsorption, thus greatly extending the cleaning cycle. The rate of bioaccumulation and biofouling of the FILMTEC CR series elements is very low, so the average feed water pressure is very low, thereby significantly reducing the energy consumption.

[0016] Preferably, the multi-stage filtration device includes a device body and a filtration medium layer disposed in the inner cavity of the device body. The filtration medium layer includes a pebble support layer at the bottom, a coarse sand layer above the pebble support layer, a fiber ball layer above the coarse sand layer, a bituminous coal layer above the fiber ball layer, and a fine sand layer above the bituminous coal layer.

[0017] Preferably, the pretreatment device includes a sedimentation tank, a softening tank, a coagulation tank arranged in sequence along the sewage treatment direction, and a grille arranged at the end of the coagulation tank. A softening agent dosing structure is arranged on the softening tank, and a coagulant dosing structure is arranged on the coagulation tank.

[0018] Preferably, a non-oxidizing biocide dosing device is also arranged on the coagulation tank to periodically dose and sterilize the system to control the microbial contamination of the membrane in the control system.

[0019] By implementing the above technical solutions, the utility model has the following beneficial effects:

[0020] According to the operation conditions of the reverse osmosis device, the utility model flushes it. During the flushing process, the reverse osmosis devices are alternately replaced, which does not affect the sewage treatment process. At the same time, by combining the concentrated water reflux of the reverse osmosis device and the optimization of the filter medium layer, the problem of low sewage treatment efficiency caused by the influence of microbial attachment on the reverse osmosis device is overcome. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following will describe in detail the preferred embodiments of the utility model through the drawings to help understand the technical solutions of the utility model, where:

[0022] Figure 1 is a schematic flow chart of the advanced sewage treatment system shown in an embodiment of the present invention;

[0023] Figure 2 is a partial schematic flow chart of the advanced sewage treatment system shown in another embodiment of the present invention;

[0024] Figure 3 is a schematic structural diagram of the multi-stage filtration device shown in the present invention.

[0025] In the figure, 10 - pretreatment device, 11 - sedimentation tank, 12 - softening tank, 13 - coagulation tank, 14 - grille, 20 - multi-stage filtration device, 201 - pebble support layer, 202 - coarse sand layer, 203 - fiber ball layer, 204 - anthracite layer, 205 - fine sand layer, 30 - security filter, 40 - ultrafiltration device, 50 - reverse osmosis device, 501 - inlet water pump, 60 - flushing device, 601 - flushing water pump, 70 - water flow sensor, 80 - water pressure sensor, 50-1 second-stage reverse osmosis device, 501-1 - second-stage inlet water pump, 60-1 - second-stage flushing device, 601-1 - second-stage flushing water pump, 70-1 - second-stage water flow sensor, 80-1 - second-stage water pressure sensor, 90 - purified water collection device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following further details the technical solutions of the utility model in conjunction with the drawings and specific embodiments.

[0027] It should be noted that the following embodiments are only used to illustrate the technical solutions of the present utility model, rather than limiting it; although the present utility model has been described in detail with reference to the following embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in each embodiment, or perform equivalent substitution on some of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of each embodiment of the present utility model.

[0028] Embodiment 1

[0029] A sewage advanced treatment system, see Figure 1 , which includes a pretreatment device, a multi - filter device, a security filter, an ultra - filtration device, a reverse osmosis device, and a purified water collection device that are connected in sequence through pipelines.

[0030] The pretreatment device performs a pretreatment on the circulating water blowdown, including a sedimentation tank, a softening tank, a coagulation tank arranged in sequence along the sewage treatment direction, and a grille arranged at the end of the coagulation tank. A softening agent dosing structure is arranged on the softening tank, and a coagulant dosing structure is arranged on the coagulation tank. The sedimentation tank mainly precipitates the raw water to remove large particles in it. Usually, some circulating water blowdown has high total salt content, high hardness, and high alkalinity. If it operates under alkaline conditions, calcium carbonate scaling will occur. A softening tank is set up, and a pH dosing structure is arranged on the water inlet side of the softening tank to adjust the pH of the raw water, soften it, and keep it slightly acidic. The coagulation tank aggregates pollutants such as suspended particles, organic matter, and heavy metals in the wastewater into larger particles through the addition of coagulants, so as to facilitate subsequent separation and treatment, which is a key step in the pretreatment process. The grille at the end of the coagulation tank plays a preliminary filtering role and can be multi - stage to increase the filtering effect.

[0031] The multi - filter device further deeply removes the suspended substances and colloids aggregated into larger particles in the sewage that has been preliminarily filtered by the grille after coagulation treatment through multiple media. As a pretreatment for precision membrane separation devices such as reverse osmosis, nanofiltration, and ultra - filtration, it protects the subsequent treatment units and extends their service life. The multi - filter device in this embodiment includes a device body and a filter medium layer built in the inner cavity of the device body. The filter medium layer includes a pebble support layer (with a thickness of 40 cm) at the bottom, a coarse sand layer (with a thickness of 35 cm) above the pebble support layer, a bituminous coal layer (with a thickness of 30 cm) above the coarse sand layer, and a fine sand layer (with a thickness of 30 cm) above the bituminous coal layer.

[0032] Two reverse osmosis devices are arranged in parallel, and a flushing device for flushing the reverse osmosis devices is provided. One flushing device can be provided, or one flushing device can correspond to each reverse osmosis device. The flushing device is connected to the reverse osmosis device through a flushing pipeline, and a water inlet pump is arranged on the water inlet pipeline of each reverse osmosis device (i.e., the pipeline connecting the reverse osmosis device and the security filtration device), and a flushing pump is arranged on the flushing pipeline. A water pressure sensor for detecting the water pressure on the water inlet side in the reverse osmosis device and a water flow sensor for detecting the water outlet flow rate on the purified water side are also arranged on the reverse osmosis device, so as to monitor the water pressure on the water inlet side and the water outlet flow rate on the purified water side in real time. The water inlet pump, the flushing pump, the water flow sensor, and the water pressure sensor are all controlled by a main controller (not shown in the figure). The main controller controls the opening and closing of the water inlet pump and the flushing pump according to the detection values of the water flow sensor and the water pressure sensor. The reverse osmosis device in this embodiment uses Dow FILMTEC™ FT30 reverse osmosis membrane elements.

[0033] Embodiment 2

[0034] The difference from Embodiment 1 is that a second-stage reverse osmosis device is added downstream of each reverse osmosis device. The concentrated water outlet end of the reverse osmosis device is connected to the second-stage reverse osmosis device. The second-stage reverse osmosis device also uses Dow FILMTEC™ FT30 reverse osmosis membrane elements. See Figure 2 . A secondary flushing device is also correspondingly arranged for the second-stage reverse osmosis device. The secondary flushing device is connected to the second-stage reverse osmosis device through a flushing pipeline, and a secondary water inlet pump is arranged on the water inlet pipeline of each second-stage reverse osmosis device, and a secondary flushing pump is arranged on the flushing pipeline. A secondary water pressure sensor for detecting the water pressure on the water inlet side in the second-stage reverse osmosis device and a secondary water flow sensor for detecting the water outlet flow rate on the purified water side are also arranged on the second-stage reverse osmosis device. Similarly, the secondary water inlet pump, the secondary flushing pump, the secondary water flow sensor, and the secondary water pressure sensor are all controlled by the main controller. The main controller controls the opening and closing of the corresponding secondary water inlet pump and secondary flushing pump according to the detection values of the water flow sensor and the water pressure sensor.

[0035] Embodiment 3

[0036] The difference from Embodiment 1 is that the multi-stage filtration device in this embodiment includes a device body and a filtration medium layer built in the inner cavity of the device body. The filtration medium layer includes a pebble support layer (with a thickness of 40 cm) at the bottom, a coarse sand layer (with a thickness of 35 cm) above the pebble support layer, a fiber ball layer (with a thickness of 30 cm) above the coarse sand layer, a bituminous coal layer (with a thickness of 30 cm) above the fiber ball layer, and a fine sand layer (with a thickness of 30 cm) above the bituminous coal layer. See Figure 3 .

Claims

1. A sewage deep treatment system, comprising a pre-treatment device, a multi-filtration device, an ultrafiltration device, a security filtration device, a reverse osmosis device and a clean water collection device connected in sequence through a pipeline, characterized in that: At least two reverse osmosis devices are arranged in parallel, and a flushing device for flushing the reverse osmosis device is provided. The flushing device is connected to the reverse osmosis device through a flushing pipe, and a water inlet pump is provided on the water inlet pipe of each reverse osmosis device, and a flushing water pump is provided on the flushing pipe. The reverse osmosis device is also provided with a water pressure sensor for detecting the water pressure on the water inlet side of the reverse osmosis device and a water flow sensor for detecting the water flow rate on the clean water side. The water inlet pump, the flushing water pump, the water flow sensor and the water pressure sensor are all controlled by a main controller.

2. A sewage deep treatment system according to claim 1, characterized in that: A portion of the concentrated water outlet of the reverse osmosis device is connected to the water inlet pipe of the reverse osmosis device through a reflux pipe connecting pipe.

3. A sewage deep treatment system according to claim 2, characterized in that: A booster pump is arranged on the reflux pipeline.

4. A sewage deep treatment system according to claim 1, characterized in that: The flushing device is connected to the clean water collecting device.

5. A sewage deep treatment system according to claim 1, characterized in that: A second-stage reverse osmosis device is also arranged downstream of the reverse osmosis device.

6. A sewage deep treatment system according to claim 1, characterized in that: The reverse osmosis device adopts Dow FILMTEC™ CR100 reverse osmosis membrane element.

7. A sewage deep treatment system according to claim 1, characterized in that: The multiple filtering device includes a device body and a filter medium layer built into the inner cavity of the device body, wherein the filter medium layer includes a pebble support layer at the bottom, a coarse sand layer above the pebble support layer, a fiber ball layer above the coarse sand layer, an anthracite layer above the fiber ball layer, and a fine sand layer above the anthracite layer.

8. A sewage deep treatment system according to claim 1, characterized in that: The pretreatment device comprises a sedimentation tank, a softening tank and a coagulation tank which are sequentially arranged along the sewage treatment direction and a grid arranged at the end of the coagulation tank. The softening tank is provided with a softener adding structure, and the coagulation tank is provided with a coagulant adding structure.

9. A sewage deep treatment system according to claim 8, characterized in that: A non-oxidizing bactericide dosing device is also provided on the coagulation tank.

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