Sewage pretreatment method and pretreatment device

Abstract

The invention relates to the technical field of sewage treatment, in particular to a sewage pretreatment method and a pretreatment device. The pretreatment method comprises the following steps: sewage is introduced into a pretreatment unit for pretreatment, and the pretreatment unit comprises a seed crystal, a crystallization inducer and an oxidizing agent. According to the sewage pretreatment method, the nucleation granulation coupling oxidation treatment technology is utilized, the content of scaling ions and organic matter in sewage can be effectively reduced, membrane pollution is relieved, the service life of a reverse osmosis assembly is prolonged, the pretreatment method is short in technological process, low in agent consumption and free of chemical sludge, the operation cost can be effectively reduced, and the method is suitable for industrial production. The sewage treatment efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a sewage pretreatment method and a pretreatment device. Background Art

[0002] As a membrane separation technology based on selective permeability, reverse osmosis technology is widely used in seawater desalination, drinking water production and wastewater deep treatment, and is considered to be an effective means to increase water supply and alleviate water shortage. In industrial wastewater treatment and reuse technology, reverse osmosis technology is widely used due to its advantages such as low energy consumption, low cost, easy operation and high purification rate. However, in actual application, ion scaling and organic adsorption will lead to membrane pore blockage, resulting in a series of problems such as decreased reverse osmosis membrane flux, reduced production efficiency, shortened membrane component life, and increased operating costs.

[0003] Therefore, in order to alleviate membrane pollution caused by ion scaling and organic adsorption in the reverse osmosis process, it is of great significance to provide a wastewater pretreatment method. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a sewage pretreatment method and a pretreatment device. The sewage pretreatment method provided by the present invention utilizes the nuclear crystal granulation coupled oxidation treatment technology, which can effectively reduce the content of scale-causing ions and organic matter in sewage, alleviate membrane pollution, and extend the service life of reverse osmosis components. In addition, the pretreatment method has a short process flow, low reagent consumption, and no chemical sludge, which can effectively reduce operating costs and improve sewage treatment efficiency.

[0005] In a first aspect, the present invention provides a sewage pretreatment method, the pretreatment method comprising: passing the sewage into a pretreatment unit for pretreatment, the pretreatment unit comprising a seed crystal, a crystallization inducer and an oxidant.

[0006] The sewage pretreatment method provided by the present invention can effectively reduce the content of scale-causing ions and organic matter in sewage, alleviate membrane pollution, and extend the service life of reverse osmosis membrane components. Specifically:

[0007] The sewage pretreatment method provided by the present invention combines the nuclear crystal granulation technology and the oxidation treatment method. The oxidant can oxidatively modify the organic pollutants, and the crystallization inducer can induce the crystallization and granulation of scale-causing ions in the sewage to form crystals through crystal seeds. The crystals are adsorbed and complexed with the oxidatively modified organic pollutants and discharged from the water body in the solid phase, thereby effectively reducing the content of scale-causing ions and organic matter in the sewage, alleviating membrane pollution, and extending the service life of the reverse osmosis membrane assembly.

[0008] As a preferred technical solution of the present invention, the seed crystal is selected from any one or more of garnet, diatomaceous earth, calcite, zeolite or modified zeolite.

[0009] As a preferred technical solution of the present invention, the amount of the seed crystals in the sewage is 1.2-2.5 g / L, for example, 1.2 g / L, 1.5 g / L, 1.8 g / L, 2.0 g / L, 2.2 g / L, 2.5 g / L, etc.

[0010] As a preferred technical solution of the present invention, the crystallization inducing agent is selected from any one or more of sodium carbonate, sodium hydroxide or sodium aluminate.

[0011] The crystallization inducing agent provided by the present invention can generate crystals through the reaction of seed crystals with scale-causing ions.

[0012] As a preferred technical solution of the present invention, the amount of the crystallization inducer in the sewage is 500-2000 mg / L, for example, 500 mg / L, 800 mg / L, 1000 mg / L, 1500 mg / L, 1800 mg / L, 2000 mg / L, etc.

[0013] As a preferred technical solution of the present invention, the oxidant is selected from ozone gas.

[0014] The ozone provided by the present invention can generate active oxygen groups, thereby oxidizing organic pollutants to modify them, and then adsorb and complex with inorganic crystals generated in situ to form a solid phase and be discharged from the water body, thereby effectively reducing the content of scale-causing ions and organic matter in sewage.

[0015] As a preferred technical solution of the present invention, the flow rate of the ozone gas is 0.5-4L / (L water·min), for example, 0.5L / (L water·min), 1L / (L water·min), 2L / (L water·min), 3L / (L water·min), 4L / (L water·min), etc.

[0016] As a preferred technical solution of the present invention, the pretreatment time is 20-60 min, for example, 20 min, 30 min, 40 min, 50 min, 60 min, etc.

[0017] As a preferred technical solution of the present invention, precipitation is performed for 2-5 minutes after the pretreatment is completed, for example, 2 minutes, 3 minutes, 4 minutes, 5 minutes, etc.

[0018] The pretreatment method provided by the present invention has a short process flow, low reagent consumption, and no chemical sludge, and can effectively reduce the content of scale-causing ions and organic matter in sewage, alleviate membrane pollution, extend the service life of reverse osmosis membrane components, significantly reduce operating costs, and improve sewage treatment efficiency.

[0019] In a second aspect, the present invention provides a sewage pretreatment device, which includes at least one pretreatment unit and a reverse osmosis component connected in sequence, wherein the pretreatment unit includes a crystal seed, a crystallization inducer and an oxidant, and the reverse osmosis component includes a reverse osmosis membrane.

[0020] It is understandable that the seed crystal, crystallization inducer and oxidant are the same as the seed crystal, crystallization inducer and oxidant described in the first aspect of the present invention. The pretreatment unit of the sewage pretreatment device provided by the present invention can be single-stage or multi-stage, so that sewage can be pretreated according to actual conditions and membrane pollution can be effectively alleviated.

[0021] The sewage pretreatment method described in the first aspect of the present invention can utilize the sewage pretreatment device provided by the present invention to treat sewage. The sewage first enters the pretreatment unit for nuclear crystal granulation coupled with ozonation treatment. The crystallization inducer induces the crystallization and granulation of scale-causing ions in the sewage through crystal seeds. Ozone oxidizes and modifies organic pollutants. The treated scale-causing ions are adsorbed and complexed with organic pollutants and discharged from the water body in the solid phase. The content of scale-causing ions and organic pollutants in the sewage entering the reverse osmosis component is reduced, and the reverse osmosis membrane flux is improved, thereby effectively alleviating membrane pollution, extending the service life of the reverse osmosis component, and significantly reducing operating costs, thereby improving sewage treatment efficiency.

[0022] As a preferred technical solution of the present invention, the reverse osmosis component is provided with two water outlets, one of which is connected to the pretreatment unit to return the reverse osmosis concentrated water to the pretreatment unit for further treatment, and the other outlet discharges purified water.

[0023] The sewage pretreatment device provided by the present invention can realize the cyclic treatment of sewage, and the reverse osmosis concentrated water flowing out of the reverse osmosis component, that is, the sewage that has not yet reached the standard, can enter the pretreatment unit for reprocessing until it reaches the standard.

[0024] The technical solution provided by the embodiment of the present invention has the following advantages compared with the prior art:

[0025] The sewage pretreatment method provided by the present invention utilizes nuclear crystal granulation coupled oxidation treatment technology, which can effectively reduce the content of scale-causing ions and organic matter in sewage, alleviate membrane pollution, and extend the service life of reverse osmosis components. In addition, the pretreatment method has a short process flow, low reagent consumption, and no chemical sludge, which can effectively reduce operating costs and improve sewage treatment efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 This is a flow chart of sewage pretreatment according to Example 1 of the present invention. DETAILED DESCRIPTION

[0029] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0031] Example 1

[0032] This embodiment provides a sewage pretreatment method and a sewage pretreatment device.

[0033] The sewage pretreatment device includes a pretreatment unit and a reverse osmosis component which are connected to each other; the pretreatment unit includes a seed crystal, a crystallization inducer and an oxidant; the reverse osmosis component includes a reverse osmosis membrane and is provided with two water outlets, one of which is connected to the pretreatment unit to return the reverse osmosis concentrated water to the pretreatment unit for further treatment, and the other water outlet discharges clean water.

[0034] The pretreatment method flow chart is as follows Figure 1 As shown, the specific steps are as follows:

[0035] The reverse osmosis concentrated water from a chemical plant was used as the sewage to be treated, with a calcium ion concentration of 400 mg / L, a magnesium ion concentration of 200 mg / L, and a COD of 3292 mg / L. Garnet was used as a seed crystal with a dosage of 2 g / L, sodium hydroxide and sodium carbonate were used as crystallization inducers, with a sodium carbonate dosage of 800 mg / L, a sodium hydroxide dosage of 1000 mg / L, and an ozone dosage of 2 L / (L water min). The sewage was passed into the pretreatment unit for nuclear crystal granulation coupled with ozonation pretreatment, pretreated for 30 minutes, precipitated for 2 minutes, and then entered the reverse osmosis membrane module. After 24 hours of filtration, the membrane flux dropped to 60% of the initial flux.

[0036] Example 2

[0037] This embodiment provides a sewage pretreatment method, which is performed by the sewage pretreatment device described in Embodiment 1. The pretreatment method comprises the following steps:

[0038] Ultra-high pressure reverse osmosis concentrated water was used as the sewage to be treated, with a calcium ion concentration of 400 mg / L, a magnesium ion concentration of 200 mg / L, and a COD of 3292 mg / L. Diatomaceous earth was used as a seed crystal, with a dosage of 1.2 g / L, sodium hydroxide and sodium carbonate as crystallization inducers, with a sodium carbonate dosage of 800 mg / L, a sodium hydroxide dosage of 1000 mg / L, and an ozone dosage of 0.4 L / (L water min). The sewage was passed into the pretreatment unit for nuclear crystal granulation coupled with ozonation pretreatment, pretreated for 60 minutes, precipitated for 2 minutes, and then entered the reverse osmosis membrane assembly. After 24 hours of filtration, the membrane flux dropped to 50% of the initial flux.

[0039] Example 3

[0040] This embodiment provides a sewage pretreatment method, which is performed by the sewage pretreatment device described in Embodiment 1. The pretreatment method comprises the following steps:

[0041] The ultra-high pressure reverse osmosis concentrated water was used as the sewage to be treated, with a calcium ion concentration of 400 mg / L, a magnesium ion concentration of 200 mg / L, and a COD of 3292 mg / L. Modified zeolite was used as a seed crystal with a dosage of 2.5 g / L, sodium hydroxide and sodium carbonate were used as crystallization inducers, with a sodium carbonate dosage of 800 mg / L, a sodium hydroxide dosage of 1000 mg / L, and an ozone dosage of 4 L / (L water min). The sewage was passed into the pretreatment unit for nuclear crystal granulation coupled with ozonation pretreatment, pretreated for 40 minutes, precipitated for 2 minutes, and then entered the reverse osmosis membrane module. After 24 hours of filtration, the membrane flux dropped to 68% of the initial flux.

[0042] Comparative Example 1

[0043] This comparative example provides a sewage pretreatment method, which is carried out by the sewage pretreatment device described in Example 1. The pretreatment method of this comparative example is the same as that of Example 1, and the difference from Example 1 is that ozone gas is not introduced in this comparative example. After 24 hours of filtration, the membrane flux dropped to 20% of the initial flux.

[0044] Comparative Example 2

[0045] This comparative example provides a sewage pretreatment method, which is carried out by the sewage pretreatment device described in Example 1. The pretreatment method of this comparative example is the same as that of Example 1, and the difference from Example 1 is that no crystallization inducer is added in this comparative example. After 24 hours of filtration, the membrane flux dropped to 30% of the initial flux.

[0046] Comparative Example 3

[0047] This comparative example provides a sewage pretreatment method, which is carried out by the sewage pretreatment device described in Example 1. The pretreatment method of this comparative example is the same as that of Example 1, and the difference from Example 1 is that no seed crystal is added in this comparative example. After 24 hours of filtration, the membrane flux drops to 10% of the initial flux.

[0048] It can be found from the embodiments and comparative examples that the sewage pretreatment method provided by the present invention can effectively alleviate membrane pollution, extend the service life of the reverse osmosis component, and has a short process flow, low reagent consumption, and no chemical sludge, which can effectively reduce operating costs and improve sewage treatment efficiency.

[0049] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0050] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments described herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sewage pretreatment method, characterized in that: The pretreatment method comprises: passing sewage into a pretreatment unit for pretreatment, wherein the pretreatment unit comprises crystal seeds, a crystallization inducer and an oxidant.

2. The sewage pretreatment method according to claim 1, characterized in that: The seed crystals are selected from any one or more of garnet, diatomaceous earth, calcite, zeolite or modified zeolite.

3. The sewage pretreatment method according to claim 1 or 2, characterized in that: The amount of the seed crystals in the sewage is 1.2-2.5 g / L.

4. The sewage pretreatment method according to any one of claims 1 to 3, characterized in that: The crystallization inducing agent is selected from any one or more of sodium carbonate, sodium hydroxide or sodium aluminate.

5. The sewage pretreatment method according to any one of claims 1 to 4, characterized in that: The amount of the crystallization inducer in the sewage is 500-2000 mg / L.

6. The sewage pretreatment method according to any one of claims 1 to 5, characterized in that: The oxidant is selected from ozone gas.

7. The sewage pretreatment method according to claim 5, characterized in that: The flow rate of the ozone gas is 0.5-4 L / (L water·min).

8. The sewage pretreatment method according to any one of claims 1 to 7, characterized in that: The pretreatment time is 20-60min; Preferably, precipitation is performed for 2-5 minutes after the pretreatment is completed.

9. A sewage pretreatment device, characterized in that: The pretreatment device comprises at least one pretreatment unit and a reverse osmosis component which are connected in sequence. The pretreatment unit comprises a seed crystal, a crystallization inducer and an oxidant, and the reverse osmosis component comprises a reverse osmosis membrane.

10. The sewage pretreatment device according to claim 9, characterized in that: The reverse osmosis component is provided with two water outlets, one of which is connected to the pretreatment unit to return the reverse osmosis concentrated water to the pretreatment unit for further treatment, and the other water outlet discharges purified water.

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