Wastewater treatment method and wastewater treatment system

Abstract

The invention provides a wastewater treatment method and a wastewater treatment system. The wastewater treatment method comprises the following steps: introducing wastewater into a catalytic oxidation reactor, and adding a catalyst into the catalytic oxidation reactor; introducing oxygen into the catalytic oxidation reactor so as to carry out catalytic oxidation treatment on the wastewater; introducing the wastewater subjected to catalytic oxidation treatment into a flocculation sedimentation tank, and adding a flocculating agent into the flocculation sedimentation tank; and stirring and standing the wastewater in the flocculation sedimentation tank to obtain treated clear water. The method can effectively remove the refractory organic matters and pigments in the wastewater, so that deep treatment of colored wastewater containing the refractory organic matters is facilitated, and up-to-standard discharge of the wastewater is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and specifically belongs to a wastewater treatment method and a wastewater treatment system. Background Art

[0002] Wastewater treatment is an important part of environmental protection and sustainable development. Wastewater mainly comes from industrial production, agricultural production, domestic sewage and rainwater runoff. These wastewaters contain a large amount of organic matter, heavy metals, pathogenic microorganisms and other harmful substances. If they are discharged directly without treatment, they will cause serious damage to the ecological environment of the water body and affect human health and ecological balance.

[0003] In the related art, wastewater is usually treated by methods such as biological treatment and physical adsorption. However, when faced with colored wastewater containing difficult-to-degrade organic matter such as printing and dyeing wastewater, these wastewater treatment methods are difficult to achieve ideal water treatment effects.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first object of the present invention is to provide a wastewater treatment method, which can effectively remove the difficult-to-degrade organic matter and pigments in the wastewater, thereby helping to achieve deep treatment of colored wastewater containing difficult-to-degrade organic matter and ensure that the wastewater meets discharge standards.

[0006] The second object of the present invention is to provide a wastewater treatment system used in the above-mentioned wastewater treatment method. The wastewater treatment system has a simple structure and occupies a small area. When applied to wastewater treatment, it can achieve good water treatment effects.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: The present invention provides a wastewater treatment method, comprising the following steps: introducing wastewater into a catalytic oxidation reactor, and adding a catalyst into the catalytic oxidation reactor; Introducing oxygen into the catalytic oxidation reactor to perform catalytic oxidation treatment on the wastewater; introducing the wastewater treated by the catalytic oxidation into a flocculation sedimentation tank, and adding a flocculant into the flocculation sedimentation tank; The wastewater in the flocculation sedimentation tank is stirred and allowed to stand to obtain treated clean water.

[0008] In the present invention, wastewater is first introduced into a catalytic oxidation reactor, and catalytic oxidation is carried out under the action of a catalyst and oxygen, thereby converting the refractory organic matter in the wastewater into low-toxic or non-toxic small-molecule compounds. After catalytic oxidation treatment, the wastewater is introduced into a flocculation sedimentation tank, and flocculation and precipitation are carried out under the action of a flocculant. In this process, the pigments, small-molecule compounds and some of the refractory organic matter that may remain in the wastewater form large-particle flocs under the action of the flocculant, and then they are separated from the wastewater by precipitation to obtain treated clean water. In short, the method is simple to operate, and can effectively remove refractory organic matter and pigments in the wastewater, thereby helping to achieve deep treatment of colored wastewater containing refractory organic matter and ensuring that the wastewater meets the discharge standards.

[0009] Preferably, the catalyst is added in an amount of 25-50 ppm.

[0010] It can be understood that the amount of catalyst added is 25-50ppm, that is, after the catalyst is added to the wastewater, the content of the catalyst in the wastewater is 25-50ppm. In the present invention, the amount of catalyst added is limited. This is because if the catalyst is too little, it is difficult to convert all the difficult-to-degrade organic matter in the wastewater into low-toxic or non-toxic small molecule compounds. If the catalyst is too much, the production cost is increased, and too much catalyst will also affect the flocculation and sedimentation effect in the subsequent process, which may lead to poor wastewater treatment effect.

[0011] Preferably, the catalyst is a nano metal oxide catalyst and / or a noble metal supported catalyst.

[0012] Preferably, the catalyst is a mixture of a nano metal oxide catalyst and a noble metal supported catalyst.

[0013] Preferably, the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst in the catalyst is 1:(1-2).

[0014] Preferably, the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst in the catalyst is 1:(1.1-1.5).

[0015] Preferably, the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst in the catalyst is 1:1.2.

[0016] In the present invention, the selection of catalyst is very important. The selection of a suitable catalyst requires comprehensive consideration of the pollutants in the wastewater, the catalyst type, the catalytic effect and other factors. The present invention selects nano metal oxide catalysts and / or precious metal supported catalysts as catalysts in the catalytic oxidation treatment stage. These catalysts have efficient catalytic effects and are environmentally friendly catalysts themselves, have environmentally friendly characteristics, and will not cause secondary pollution to the environment.

[0017] In a further embodiment of the present invention, a mixture of a nano metal oxide catalyst and a noble metal supported catalyst is selected as a catalyst. Wherein, the nano metal oxide has a higher specific surface area and active sites, thereby improving the catalytic efficiency. The nanostructure helps to improve the stability and selectivity of the catalyst. The noble metals of the noble metal supported catalyst themselves have excellent catalytic performance. When they are loaded on a porous carrier in the form of nanoparticles, the catalytic activity and selectivity can be further improved. The supported catalyst not only improves the utilization rate of the noble metal, but also enhances the stability and regeneration ability of the catalyst. The mixed use of the two catalysts can not only combine their respective advantages to improve the catalytic efficiency, selectivity and stability, but also make the two catalysts cooperate with each other to further improve the catalytic effect. Specifically, the two catalysts have different active sites, which can act on the reactants (i.e., the difficult-to-degrade organic matter in the wastewater) together, thereby improving the catalytic efficiency. And the nano metal oxide catalyst and the noble metal supported catalyst can stabilize the active sites mutually, which helps to extend the service life of the catalyst and improve the stability of the catalyst. In addition, the mixed catalyst can change the reaction path, make the reaction easier to carry out, and reduce the generation of by-products. In conclusion, the present invention can further enhance the decomposition ability of refractory organic matter by mixing two catalysts, thereby facilitating further purification of wastewater.

[0018] In the present invention, the mass ratio of the nano metal oxide catalyst and the noble metal supported catalyst is limited. This is because if there are too many noble metal supported catalysts or too many nano metal oxide catalysts, the reaction path may not meet expectations, thereby affecting the catalytic effect, and when one of the catalysts is too much, the active sites of the other catalyst may be inhibited, affecting its catalytic performance. By limiting the mass ratio between the two catalysts, the present invention can optimize the reaction path, make the catalytic oxidation reaction proceed in the desired direction, and can maximize the synergistic effect of the two catalysts, thereby further improving the catalytic performance.

[0019] Preferably, the added amount of the flocculant is 80-100 ppm.

[0020] In the present invention, the amount of flocculant added is limited. When the amount of flocculant added is 80-100ppm, larger flocs can be produced, and the flocs settle quickly, which helps to improve the subsequent sedimentation separation efficiency. When the amount of flocculant added is less than 80ppm, the produced flocs are too small and the sedimentation rate is slow, which affects the wastewater treatment efficiency. When the amount of flocculant added is greater than 100ppm, excess flocculant causes charge reversal, making the flocs easy to float but not easy to settle, affecting the treatment effect. Therefore, in the present invention, the amount of flocculant added is limited to 80-100ppm.

[0021] Preferably, the flocculant is polyaluminium chloride and / or polyacrylamide.

[0022] In the present invention, the selection of flocculants is very important. The selection of suitable flocculants needs to comprehensively consider water quality characteristics, flocculant type, flocculation effect, cost, environmental friendliness and other factors. In the present invention, polyaluminum chloride and / or polyacrylamide are selected as flocculants. Compared with other flocculants, these two flocculants have good flocculation effect and are environmentally friendly materials, which will not cause secondary pollution to the environment.

[0023] Preferably, the flocculant is a mixture of polyaluminium chloride and polyacrylamide.

[0024] Preferably, the adding flocculant to the flocculation sedimentation tank comprises: adding polyaluminium chloride to the flocculation sedimentation tank, waiting for a preset time, and then adding polyacrylamide.

[0025] Preferably, the mass ratio of polyaluminium chloride to polyacrylamide in the flocculant is (30-20):1.

[0026] Preferably, the mass ratio of polyaluminium chloride to polyacrylamide in the flocculant is 25:1.

[0027] In a further scheme of the present invention, the type of flocculant is limited, that is, the flocculant is a mixture of polyaluminium chloride (PAC) and polyacrylamide (PAM). In the process of the invention, the inventor found that the mixed use of PAC and PAM can produce synergistic effects, improve the flocculation effect, and the formed flocs are easier to settle, thereby improving the treatment effect of wastewater. Specifically, PAC, as an inorganic polymer flocculant, has a strong adsorption effect on the surface of the particle for the opposite ions, opposite colloid particles or chain ions with opposite charges. This adsorption neutralizes part of its charge, reduces electrostatic repulsion, and is easier to approach other particles and adsorb each other to form flocs. These flocs are relatively small. PAM, as a polymer flocculant, can aggregate these small flocs through its long chain structure to form larger flocs. These large flocs are easier to settle and filter, which is beneficial to improve the wastewater treatment efficiency. In a further scheme of the present invention, the order of adding the two flocculants is also limited, that is, polyaluminium chloride is added first, and after waiting for a preset time, polyacrylamide is added. As described above, PAC can form small flocs, and PAM can aggregate these small flocs to form large flocs. By limiting the order of adding the two, PAC can first play a flocculation role to form more small flocs. Then, PAM is used to form these small flocs into large flocs, thereby improving the synergistic flocculation effect of the two. In a further scheme of the present invention, the mass ratio of the two is restricted. This is because the inventors have found through research that if PAC is less, it may lead to insufficient charge neutralization of suspended particles in water, it is difficult for particles to aggregate, the flocculation effect is not good, and fewer small flocs are formed, and thus the bridging effect of PAM cannot be fully exerted (i.e., these small flocs are aggregated through its long chain structure). If PAC is too much, the flocs may be too loose and difficult to settle, and the bridging effect of PAM may be inhibited. In addition, from the cost aspect, PAC has a lower cost and PAM has a higher cost. Taking the above factors into consideration, the present invention limits the mass ratio of polyaluminium chloride to polyacrylamide to (30-20):1, and further limits it to 25:1. Under this ratio, PAC and PAM can exert a good flocculation synergistic effect, improve flocculation efficiency, and also play a role in reducing costs.

[0028] Preferably, the temperature of the catalytic oxidation treatment is 50-70°C; Preferably, the pressure of the catalytic oxidation treatment is 1.15-1.25 standard atmospheric pressure; Preferably, the flow rate of the oxygen gas is 10-15 sccm.

[0029] In the present invention, by selecting appropriate catalytic oxidation temperature, pressure and oxygen flow rate, the catalytic oxidation efficiency can be improved, thereby improving the wastewater treatment efficiency.

[0030] The present invention also provides a wastewater treatment system for implementing the above wastewater treatment method, the system comprising: a catalytic oxidation reactor and a flocculation sedimentation tank arranged in sequence along the flow direction of the wastewater, and a mud discharge pipe is arranged at the bottom of the flocculation sedimentation tank.

[0031] In the present invention, the wastewater is subjected to catalytic oxidation treatment in a catalytic oxidation reactor to convert the refractory organic matter in the wastewater into low-toxic or non-toxic small-molecule compounds. Then, the wastewater is introduced into a flocculation sedimentation tank, and the pigments, small-molecule compounds and some of the refractory organic matter that may remain in the wastewater are flocculated and precipitated by the flocculation sedimentation tank, and the precipitate obtained by the precipitation can be discharged through a mud discharge pipe, thereby obtaining treated clean water.

[0032] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention sequentially performs catalytic oxidation treatment and flocculation precipitation on wastewater, thereby utilizing catalytic oxidation treatment to convert the refractory organic matter in the wastewater into low-toxic or non-toxic small-molecule compounds, and flocculates and precipitates the pigments, small-molecule compounds, and some of the refractory organic matter that may remain in the wastewater under the action of a flocculant, thereby improving the wastewater treatment effect, achieving deep treatment of colored wastewater containing refractory organic matter, and ensuring that the wastewater meets discharge standards; (2) The method of the present invention is simple to operate and can be easily industrialized; (3) The method of the present invention has good economic benefits, low costs and high economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 A schematic diagram of a wastewater treatment system provided by an embodiment of the present invention.

[0034] In the figure: 10, catalytic oxidation reactor; 20, flocculation sedimentation tank; 30, sludge discharge pipe. DETAILED DESCRIPTION

[0035] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments and the accompanying drawings of the specification, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If the specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0036] Example 1 See also Figure 1 As shown, this embodiment provides a wastewater treatment system, which includes a catalytic oxidation reactor 10 and a flocculation sedimentation tank 20 arranged in sequence along the flow direction of the wastewater, and a mud discharge pipe 30 is arranged at the bottom of the flocculation sedimentation tank.

[0037] In this embodiment, the wastewater is treated by the following workflow: the wastewater is introduced into a catalytic oxidation reactor, and 35ppm of catalyst is added to the catalytic oxidation reactor, wherein the catalyst is obtained by mixing a nano metal oxide catalyst and a noble metal supported catalyst, and the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst is 1:1.2. The nano metal oxide catalyst is specifically cobalt oxide, and the noble metal supported catalyst is a rhodium aluminum oxide catalyst. Then, 13sccm is introduced into the catalytic oxidation reactor at 65°C and a pressure of 1.2 standard atmospheric pressure to catalytically oxidize the wastewater. After catalytic oxidation treatment, the wastewater is introduced into a flocculation sedimentation tank, PAC is added to the flocculation sedimentation tank, and PAM is added after waiting for 60s, wherein the mass ratio of PAC to PAM is 25:1, and the content of flocculant (including PAC and PAM) in the wastewater is 90ppm; the wastewater in the flocculation sedimentation tank is stirred at a speed of 75 rpm for 5 minutes, and after the stirring is completed, it is allowed to stand for 30 minutes to allow the flocs in the wastewater to settle. Finally, the sediment settled at the bottom of the flocculation sedimentation tank is discharged through the sludge discharge pipe to obtain treated clean water.

[0038] Example 2 The only difference between this embodiment and embodiment 1 is that the nano metal oxide catalyst used is copper oxide.

[0039] Example 3 The only difference between this embodiment and embodiment 1 is that the nano metal oxide catalyst used is titanium dioxide.

[0040] Example 4 The only difference between this embodiment and embodiment 1 is that the noble metal supported catalyst used is a platinum alumina catalyst.

[0041] Example 5 The only difference between this embodiment and embodiment 1 is that the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst is 1:1.

[0042] Example 6 The only difference between this embodiment and embodiment 1 is that the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst is 1:1.1.

[0043] Example 7 The only difference between this embodiment and embodiment 1 is that the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst is 1:1.5.

[0044] Example 8 The only difference between this embodiment and embodiment 1 is that the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst is 1:2.

[0045] Example 9 The only difference between this embodiment and embodiment 1 is that the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst is 1:5.

[0046] Example 10 The only difference between this embodiment and embodiment 1 is that the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst is 2:1.

[0047] Embodiment 11 The only difference between this embodiment and embodiment 1 is that the catalyst used is cobalt oxide.

[0048] Example 12 The only difference between this embodiment and embodiment 1 is that the catalyst used is a rhodium alumina catalyst.

[0049] Example 13 The only difference between this embodiment and embodiment 1 is that the amount of catalyst added is 25 ppm.

[0050] Embodiment 14 The only difference between this embodiment and embodiment 1 is that the amount of catalyst added is 50 ppm.

[0051] Embodiment 15 The only difference between this embodiment and embodiment 1 is that the amount of catalyst added is 15 ppm.

[0052] Example 16 The only difference between this embodiment and embodiment 1 is that the amount of catalyst added is 70 ppm.

[0053] Embodiment 17 The only difference between this embodiment and embodiment 1 is that the amount of flocculant added is 80 ppm.

[0054] Embodiment 18 The only difference between this embodiment and embodiment 1 is that the amount of flocculant added is 100 ppm.

[0055] Embodiment 19 The only difference between this embodiment and embodiment 1 is that the amount of flocculant added is 50 ppm.

[0056] Embodiment 20 The only difference between this embodiment and embodiment 1 is that the amount of flocculant added is 150 ppm.

[0057] Embodiment 21 The only difference between this embodiment and embodiment 1 is that the mass ratio of PAC to PAM is 20:1.

[0058] Embodiment 22 The only difference between this embodiment and embodiment 1 is that the mass ratio of PAC to PAM is 30:1.

[0059] Embodiment 23 The only difference between this embodiment and embodiment 1 is that the mass ratio of PAC to PAM is 10:1.

[0060] Embodiment 24 The only difference between this embodiment and embodiment 1 is that the mass ratio of PAC to PAM is 50:1.

[0061] Embodiment 25 The only difference between this embodiment and embodiment 1 is that the flocculant is PAC.

[0062] Embodiment 26 The only difference between this embodiment and embodiment 1 is that the flocculant is PAM.

[0063] Embodiment 27 The difference between this embodiment and embodiment 1 is that the order of adding PAC and PAM is different, that is, PAM is added to the flocculation sedimentation tank, and PAC is added after waiting for 60 seconds.

[0064] Embodiment 28 The only difference between this embodiment and embodiment 1 is that the temperature of the catalytic oxidation treatment is 50°C.

[0065] Embodiment 29 The only difference between this embodiment and embodiment 1 is that the temperature of the catalytic oxidation treatment is 70°C.

[0066] Embodiment 30 The only difference between this embodiment and embodiment 1 is that the pressure of the catalytic oxidation treatment is 1.15 standard atmospheric pressure.

[0067] Embodiment 31 The only difference between this embodiment and embodiment 1 is that the pressure of the catalytic oxidation treatment is 1.25 standard atmospheric pressure.

[0068] Embodiment 32 The only difference between this embodiment and embodiment 1 is that the flow rate of oxygen is 10 sccm.

[0069] Embodiment 33 The only difference between this embodiment and embodiment 1 is that the flow rate of oxygen is 15 sccm.

[0070] Experimental example The wastewater (COD: 3031 mg / L, chromaticity: 230) was treated by using the wastewater treatment methods of Examples 1-30 and the prior art, respectively. The water quality of the treated clean water is shown in Tables 1-3 below.

[0071] Table 1 Wastewater treatment results of Examples 1-16

[0072] Table 2 Wastewater treatment results of Examples 17-24

[0073] Table 3 Wastewater treatment results of Examples 28-33 and prior art

[0074] According to the above data, it can be seen that the scheme of the present invention can effectively reduce the COD and chromaticity of wastewater, among which Example 1 has the best effect. The COD in the treated wastewater is only 60 mg / L and the chromaticity is only 15.

[0075] By comparing Example 1 with Examples 5-10, it can be seen that the wastewater treatment effects of Examples 9 and 10 are significantly lower than those of the other examples. This may be because when one of the catalysts is excessive, it may inhibit the active sites of the other catalyst, affecting the overall catalytic performance, and further affecting the degradation effect of the difficult-to-degrade organic matter, resulting in a higher COD in the final clean water.

[0076] By comparing Example 1 with Examples 11-12, it can be seen that the wastewater treatment effects of Examples 11 and 12 are significantly lower than those of Example 1. This may be because when a mixture of a nano-metal oxide catalyst and a noble metal-supported catalyst is used as a catalyst, there is a synergistic catalytic effect, and the different active sites each has can act on the reactants together, and can stabilize the active sites with each other, thereby improving the catalyst stability and ensuring good catalytic performance, thereby enhancing the decomposition ability of difficult-to-degrade organic matter and improving the wastewater treatment effect.

[0077] By comparing Example 1 with Examples 13-16, it can be seen that the wastewater treatment effect of Example 1 is significantly better than that of Examples 13-16, and the wastewater treatment effects of Examples 15 and 16 are the worst. This may be because too little catalyst is used in Example 15, which cannot play a good catalytic role. In Example 16, there are too many catalysts, and the excess catalyst inhibits the subsequent flocculation effect, resulting in significantly higher COD and chromaticity in the treated wastewater than in other examples.

[0078] By comparing Example 1 with Examples 17-20, it can be seen that the wastewater treatment effects of Examples 19 and 20 are significantly lower than those of the other examples. This may be because when the amount of flocculant added is less than 80 ppm, the flocs produced are too small and the sedimentation rate is slow, which affects the wastewater treatment efficiency. When the amount of flocculant added is greater than 100 ppm, the excess flocculant causes charge reversal, making the flocs easy to float but difficult to settle, affecting the treatment effect.

[0079] By comparing Example 1 with Examples 21-24, it can be seen that the wastewater treatment effects of Examples 23 and 24 are significantly lower than those of the other examples. This may be because when PAC is too little, the charge neutralization of the suspended particles in the water is insufficient, and fewer small flocs are formed, so that PAM cannot fully play its bridging role, resulting in poor wastewater treatment effects. When PAC is too much, the flocs may be too loose and difficult to settle, and may inhibit the bridging effect of PAM, resulting in poor wastewater treatment effects.

[0080] Comparing Example 1 with Examples 25-26, it can be seen that the wastewater treatment effect of Example 1 is significantly better than that of Examples 25 and 26. This may be because the mixed use of PAC and PAM can produce a synergistic effect, PAC can neutralize negatively charged particles in water to form small flocs, and PAM can aggregate these small flocs through its long chain structure to form large flocs that are conducive to sedimentation and filtration, thereby improving the wastewater treatment efficiency.

[0081] By comparing Example 1 and Example 27, it can be seen that the wastewater treatment effect of Example 1 is significantly better than that of Example 27. This may be because after changing the addition order, PAM is consumed prematurely, and thus cannot bridge the small flocs formed by PAC, affecting the overall flocculation and sedimentation effect.

[0082] In conclusion, the method of the present invention can effectively remove the refractory organic matter and pigments in wastewater, thereby helping to achieve deep treatment of colored wastewater containing refractory organic matter and ensuring that the wastewater is discharged in compliance with the discharge standards.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wastewater treatment method, characterized in that: The steps include: introducing wastewater into a catalytic oxidation reactor, and adding a catalyst into the catalytic oxidation reactor; Introducing oxygen into the catalytic oxidation reactor to perform catalytic oxidation treatment on the wastewater; introducing the wastewater treated by the catalytic oxidation into a flocculation sedimentation tank, and adding a flocculant into the flocculation sedimentation tank; The wastewater in the flocculation sedimentation tank is stirred and allowed to stand to obtain treated clean water.

2. The wastewater treatment method according to claim 1, characterized in that: The added amount of the catalyst is 25-50 ppm.

3. The wastewater treatment method according to claim 1 or 2, characterized in that: The catalyst is a nano metal oxide catalyst and / or a noble metal supported catalyst.

4. The wastewater treatment method according to claim 3, characterized in that: The catalyst is a mixture of a nano metal oxide catalyst and a noble metal supported catalyst.

5. The wastewater treatment method according to claim 4, characterized in that: The mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst in the catalyst is 1:(1-2); Preferably, the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst in the catalyst is 1:(1.1-1.5); Preferably, the mass ratio of the nano metal oxide catalyst to the noble metal supported catalyst in the catalyst is 1:1.

2.

6. The wastewater treatment method according to claim 1, characterized in that: The added amount of the flocculant is 80-100 ppm.

7. The wastewater treatment method according to claim 1 or 6, characterized in that: The flocculant is polyaluminium chloride and / or polyacrylamide.

8. The wastewater treatment method according to claim 7, characterized in that: The flocculant is a mixture of polyaluminium chloride and polyacrylamide; Preferably, the adding of flocculant to the flocculation sedimentation tank comprises: adding polyaluminium chloride to the flocculation sedimentation tank, waiting for a preset time, and then adding polyacrylamide; Preferably, the mass ratio of polyaluminium chloride to polyacrylamide in the flocculant is (30-20):1; Preferably, the mass ratio of polyaluminium chloride to polyacrylamide in the flocculant is 25:

1.

9. The wastewater treatment method according to claim 1, characterized in that: The temperature of the catalytic oxidation treatment is 50-70°C; Preferably, the pressure of the catalytic oxidation treatment is 1.15-1.25 standard atmospheric pressure; Preferably, the flow rate of the oxygen gas is 10-15 sccm.

10. A wastewater treatment system for implementing the wastewater treatment method according to any one of claims 1 to 9, characterized in that: include: A catalytic oxidation reactor and a flocculation sedimentation tank are arranged in sequence along the flow direction of the wastewater, and a mud discharge pipe is arranged at the bottom of the flocculation sedimentation tank.

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