CN104045210B - The treatment for reuse method of oil refining-Ethylene Complex unit sewage - Google Patents

Abstract

The invention relates to a method for treating and reusing wastewater from an oil refinery-ethylene unit, comprising: (1) sequentially performing wet oxidation and SBR treatment on the wastewater of oil refining alkali residue; The sewage is mixed with the wastewater treated in step (1), and the mixed sewage is treated by the biological aerated filter, the advanced oxidation and the biological aerated filter in turn, and then mixed with the acid-base wastewater and discharged; (3) the salt content is ≤ 500mg/ The waste water from L is mixed, treated in turn by oil separation, air flotation, biochemical, and biological aerated filters, sterilized and filtered, and then reused in the circulating cooling water system. The invention can greatly improve the reuse rate of sewage, has low investment and operation costs, and is easy to operate and manage.

Description

Treatment and Reuse Method of Sewage from Oil Refining-Ethylene Combined Unit

technical field

The invention relates to a treatment and reuse method for sewage of an oil refinery-ethylene combined unit.

Background technique

my country is a country with a shortage of water resources. The per capita water resources are about 2,200 cubic meters, which is only a quarter of the world average. At the same time, due to the growth of our country's population, the water demand has approached the amount of water resources that can be developed and utilized.

The petrochemical industry is one of the five high water consumption industries in my country, among which the water consumption of ethylene production is particularly prominent. A production plant with an annual output of 1 million tons of ethylene needs to draw about 18.5 million tons of water per year, and at the same time discharge sewage about 12 million tons per year. Year. Huge water consumption not only restricts the development of my country's ethylene industry, but also is a serious waste of water resources. Reusing sewage from the ethylene industry after treatment can not only solve the problem of environmental pollution caused by discharged sewage, but also greatly reduce water intake, which is an inevitable requirement for saving water resources and achieving sustainable development.

There are many types of sewage from ethylene plants and their components are complex. The existing treatment methods are mainly to mix all kinds of sewage from ethylene plants and then treat them uniformly. At present, most ethylene plants still use the "old three sets" process consisting of oil separation, air flotation and biochemical treatment of mixed sewage. Due to the impact of high-concentration sewage on the biochemical system, the sewage treated with the "old three sets" process is still not enough Stably meet the national first-level emission standards, let alone reuse. Some enterprises can realize partial reuse of sewage through advanced treatment of sewage, but the reuse rate of sewage is not ideal, and the investment of sewage reuse is high, the operation cost is high, and there is no economic benefit. Some oil refineries have adopted the measures of "cleaning and diverting sewage, separating and treating sewage", so that high and low concentration wastewater can be treated separately. The overall treatment effect is good, but the sewage reuse rate is still low. The main purpose of oil refining enterprises to adopt "cleaning and diverting sewage and separating sewage and sewage" is to avoid the impact of high-concentration sewage on the biochemical system, so that the treated sewage can stably meet the national discharge standards, not for the reuse of sewage.

To sum up, on the premise of ensuring that the discharged sewage can meet the standards stably without increasing excessive costs, it is an urgent requirement for ethylene enterprises to further increase the reuse rate of sewage.

Contents of the invention

The invention provides a treatment and reuse system and method for ethylene plant sewage. By using the system and method, the reuse rate of ethylene plant sewage can be greatly improved, and the investment and operation costs are low, and the operation and management are simple and convenient. The technology is reliable.

The sewage treatment and reuse system of the ethylene plant is composed of the first sewage treatment unit, the second sewage treatment unit and the sewage reuse unit. The first sewage treatment unit includes wet oxidation reactor, first biological aerated filter, advanced Oxidation reactor and the second biological aerated filter, the second sewage treatment unit includes a grease trap, an air flotation tank, a biochemical tank and the third biological aerated filter in sequence; wherein, the outlet pipeline of the second sewage treatment unit is connected to the sewage The water inlet pipeline of the recycling unit is connected, the outlet pipeline of the sewage recycling unit is connected with the circulating cooling water system, and the circulating cooling water sewage pipeline is connected with the water inlet pipeline of the first biological aerated filter.

Preferably, the circulating cooling water discharge pipeline is also connected with the water inlet pipeline of the second sewage treatment unit.

A method for treating and recycling sewage from an ethylene plant, comprising:

(1) Alkali residue wastewater is mixed with circulating cooling water and sewage after wet oxidation treatment. The COD of the mixed sewage is ≤ 2000mg/L. The mixed sewage passes through the first biological aerated filter, advanced oxidation and second biological aerated filter in sequence After pool treatment, it is mixed with acid-base wastewater and discharged;

(2) Mix waste water with a salt content of ≤500mg/L, go through oil separation, air flotation, biochemical treatment, and the third biological aerated filter in sequence, then sterilize and filter, and then reuse it in the circulating cooling water system.

Preferably, the alkali slag wastewater is mixed with part of the circulating cooling water effluent after wet oxidation treatment; the wastewater with a salt content ≤ 500mg/L is mixed with another part of the circulating cooling water effluent before treatment.

Preferably, in step (1), the alkali slag wastewater is mixed with circulating cooling water sewage after wet oxidation treatment, so that the COD of the mixed sewage is 1500-2000 mg/L.

The wet oxidation (WO for short) belongs to the prior art, and its usual reaction conditions are: temperature 120-350°C, pressure 0.5-22MPa, residence time 15min-120min.

Described biological aerated filter (Biological Aerated Filter, abbreviated BAF) belongs to the prior art, and the present invention can adopt conventional biological aerated filter, and filter material is preferably inorganic filter material, as clay, ceramsite, volcanic rock, zeolite, Fly ash particles, etc.

The described grease trap, air flotation tank and biochemical tank belong to conventional technology. For ethylene plants with "old three sets" of processes, the "old three sets" of processes and equipment can be used.

The sewage reuse unit is used for sterilizing and filtering sewage.

The advanced oxidation refers to the generation of hydroxyl radicals during the oxidation process. Depending on the oxidant used, the pH of the wastewater needs to be adjusted. When ozone is used as the oxidant, the pH value of the waste water is 7-12, preferably 8-11. When potassium permanganate and chlorine gas are used as oxidants, the pH value of the waste water is 1-7, preferably 2-6. When hydrogen peroxide, chlorine dioxide or sodium hypochlorite is used as the oxidizing agent, the pH value of the waste water is 1-7, preferably 2-6. The advanced oxidation includes catalytic oxidation. For example, when using hydrogen peroxide, chlorine dioxide or sodium hypochlorite as an oxidant, a catalyst needs to be added. The catalyst can be selected from transition metal ions Fe ²⁺ , Mn ²⁺ , Ni ²⁺ , Co ²⁺ , Cd ²⁺ , Cu ²⁺ , Ag ⁺ , Cr ³⁺ and Zn ²⁺ or one or more of them, or one of metal oxides MnO ₂ , TiO ₂ and Al ₂ O ₃ or several.

The advanced oxidation treatment process of the present invention is preferably carried out under stirring, and the method of mechanical stirring can also be adopted, and the method of stirring with aeration or reflux can also be used. The oxidation reaction time may be 10-120 minutes, preferably 30-60 minutes.

The advanced oxidation reactor refers to a reactor capable of performing advanced oxidation treatment on sewage, which belongs to the prior art. The present invention preferably adopts a reaction tank, more preferably adopts a reaction tank with stirring equipment. The stirring equipment refers to the equipment capable of producing stirring effect, such as mechanical stirring, aeration reactor or circulating pump, etc.

In the present invention, one or several auxiliary methods in photocatalysis, electrocatalysis, ultrasonic catalysis, and magnetic catalysis can also be used to improve the effect of oxidation reaction, such as: using light + hydrogen peroxide, light + ozone, electricity + hydrogen peroxide, etc. to treat wastewater.

The present invention also provides a method for treating and reusing wastewater from an oil refinery-ethylene unit, comprising:

(1) Refinery alkali slag wastewater is sequentially subjected to wet oxidation and SBR treatment;

(2) After the ethylene alkali residue wastewater is wet-oxidized, it is mixed with the circulating cooling water sewage and the wastewater treated in step (1), so that the COD of the mixed sewage is less than or equal to 2000mg/L, and the mixed sewage is sequentially passed through the first aerated biological filter pool, advanced oxidation and the second biological aerated filter, mixed with acid-base wastewater and discharged;

(3) Mix waste water with a salt content of ≤500mg/L, and sequentially undergo oil separation, air flotation, biochemical, and third biological aerated filter treatment, then sterilize and filter, and then reuse it in the circulating cooling water system.

Preferably, the ethylene alkali slag wastewater is mixed with part of the circulating cooling water effluent and the wastewater treated in step (1) after wet oxidation treatment; the wastewater with a salt content of ≤500mg/L is mixed with another part of the circulating cooling water effluent After mixing, proceed to processing.

Preferably, in step (2), after wet oxidation treatment of ethylene alkali slag wastewater, it is mixed with circulating cooling water sewage and wastewater treated in step (1), so that the COD of the mixed sewage is 1500-2000 mg/L.

The present invention also provides another method for treating and reusing sewage from an oil refinery-ethylene unit, comprising:

(1) Mix the oil refining alkali residue wastewater with the ethylene alkali residue wastewater, after wet oxidation treatment, and then mix with the circulating cooling water sewage, so that the COD of the mixed sewage is ≤2000mg/L, and the mixed sewage is sequentially passed through the first aerated biological filter pool, advanced oxidation and the second biological aerated filter, mixed with acid-base wastewater and discharged;

(2) Mix waste water with a salt content of ≤500mg/L, and sequentially undergo oil separation, air flotation, biochemical, and third biological aerated filter treatment, then sterilize and filter, and then reuse it in the circulating cooling water system.

Preferably, the oil refinery alkali residue wastewater is mixed with ethylene alkali residue wastewater, and after wet oxidation treatment, it is mixed with part of the circulating cooling water sewage; the wastewater with a salt content of ≤500mg/L is mixed with another part of the circulating cooling water sewage After that, proceed with the processing.

Preferably, in step (1), the oil refinery alkali residue wastewater is mixed with ethylene alkali residue wastewater, and after wet oxidation treatment, it is then mixed with circulating cooling water wastewater, so that the COD of the mixed wastewater is 1500-2000 mg/L.

SBR belongs to the existing technology, also known as continuous batch bioreactor, intermittent activated sludge reactor, which has the characteristics of plug flow, anaerobic-aerobic operation, and brief water intake. It is a simple, low-consumption and fast bioreactor. Sewage treatment reactor.

The refinery-ethylene unit refers to a set of public works shared by the refinery unit and the ethylene unit, such as a shared circulating water system and steam system.

In the prior art, all ethylene sewage is mixed and treated uniformly. This brings about two main problems. One is the impact of high-concentration sewage on the biochemical system, causing the effluent quality of the biochemical system to be unstable, and may even cause the sewage to fail to meet the discharge standards; "After the process is processed, it cannot be reused. Although some sewage can be reused by adding advanced treatment facilities, the sewage reuse rate is still not ideal and the cost is too high. The inventor has comprehensively investigated and analyzed the water supply, water use, sewage and sewage treatment systems of existing ethylene enterprises, and proposed the above-mentioned technical solution through a large number of experiments. In the sewage produced by ethylene, the alkali residue wastewater and acid-base wastewater account for about 5% of the total sewage, but the salt content accounts for more than 50% of the total salt content of the sewage. Among them, the COD of acid-base wastewater is very low, while the alkali residue The COD of wastewater is very high. The invention separates the alkali slag waste water with high COD concentration and high salt content, and treats it separately through the organic combination of oxidation method and biochemical method, and finally realizes stable discharge up to standard. In ethylene production, the amount of circulating cooling water accounts for about 96% of the total water consumption of ethylene production, and the water intake accounts for about 70% of the total water intake for ethylene production. The requirements for recycled cooling water quality are relatively low. Other sewage from ethylene production (excluding circulating cooling water sewage) has low salt content. Although the COD concentration of individual sewage is high, the average COD of these sewage is not high after mixing. It can pass the conventional treatment process of the ethylene plant and increase A biological aerated filter process to meet the recycling requirements of circulating cooling water. In the present invention, other sewage produced by ethylene is mixed with circulating cooling water sewage, and after being treated by conventional sewage treatment process of ethylene plant ("old three sets" process) and biological aerated filter, it is reused in circulating cooling water sewage, thereby It has greatly improved the reuse rate of ethylene plant sewage.

Compared with the existing ethylene sewage recycling technology, the present invention has the following advantages:

1. The sewage reuse rate in the prior art generally does not exceed 70%, but the sewage reuse rate in the present invention can reach more than 70%, and the highest can reach about 95%. In addition, the invention can also avoid the impact of high-concentration sewage on the biochemical system, and realize the stable and standard discharge of sewage.

2. The existing technology requires a complex desalination process to realize sewage reuse, which has a long process flow, high technical difficulty, and poor reliability. The method of the invention does not require desalination treatment of sewage, thereby greatly shortening the process flow of sewage reuse and making the technology simpler and more reliable.

3. The existing technology requires advanced treatment of a large amount of mixed sewage to realize the reuse of sewage, which is technically difficult, long process flow, high operating costs, and economically unreasonable. The invention separates and treats the sewage, greatly reduces the amount of difficult-to-treat sewage, avoids complex desalination treatment, and shortens the process flow, so the operating cost is lower and the economy is more reasonable.

4. The prior art has great difficulty, long technological process, complicated operation and large floor area, so it is difficult to implement. Since the present invention adopts sewage separation treatment, the amount of refractory sewage is greatly reduced, desalination treatment is avoided, and only a small number of new facilities are needed (the existing "three old sets" of processes can be used), so the implementation is easier.

Description of drawings

FIG. 1 is a schematic diagram of the sewage treatment system of Comparative Example 1.

Fig. 2 is the schematic diagram of the sewage treatment system of embodiment 1.

3 is a schematic diagram of the sewage treatment system of Comparative Example 2.

FIG. 4 is a schematic diagram of the sewage treatment system in Embodiment 2.

FIG. 5 is a schematic diagram of the sewage treatment system of Comparative Example 3.

FIG. 6 is a schematic diagram of the sewage treatment system in Embodiment 3.

FIG. 7 is a schematic diagram of the sewage treatment system in Embodiment 4.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 2, one embodiment of the present invention is: all low-salt wastewater with a salt content of ≤500 mg/L in the sewage of an ethylene plant is mixed with part of the circulating cooling water sewage, and then enters the grease trap, air flotation tank, The biochemical pool and the third biological aerated filter are used for treatment. The treated sewage enters the sewage reuse unit for sterilization and filtration, and then enters the circulating water cooling system. Water and sewage are mixed, and are treated in sequence by the first biological aerated filter, catalytic oxidation (a type of advanced oxidation) and the second biological aerated filter, and the treated sewage is mixed with acid-base wastewater and discharged.

As shown in Figure 6, another two implementations of the present invention are: all low-salt wastewater with a salt content of ≤500mg/L in the ethylene plant sewage enters the oil separation tank, the air flotation tank, the biochemical tank, and the third aerated organism in sequence The treated sewage enters the sewage reuse unit for sterilization and filtration, and then enters the circulating water cooling system; the alkali slag wastewater from the ethylene plant is wet-oxidized, mixed with circulating cooling water and sewage, and then passed through the first exposure Gas biological filter, catalytic oxidation (a type of advanced oxidation) and the second biological aerated filter treatment, the treated sewage is mixed with acid-base wastewater and discharged.

The present invention is further illustrated by the following examples.

Comparative example 1

A large-scale ethylene production plant with a production capacity of 1 million t/a uses surface water with a salt content of 150 mg/L and draws 18.5 million m ³ /a of which the circulating cooling water system draws 14 million m ³ /a. The total sewage discharge is 12 million m ³ /a, including 120,000 m ³ /a of alkali residue wastewater containing 22,000 mg/L of salt and COD20,000-50,000 mg/L, and 300,000 m ³ /a of acid-base wastewater containing 48,000 mg/L of salt, containing The sewage of circulating cooling water system with salt 1250mg/L is 2.2 million m ³ /a, and other waste water with salt content less than 500 mg/L is 9.38 million m ³ /a in total.

As shown in Figure 1, all the wastewater was mixed and subjected to oil separation-air flotation-biochemical treatment. The salt content of the effluent was 2040mg/L, COD<100mg/L, and both the salt content and COD exceeded the recycled water reuse index. Requirements (salt content ≤ 1200mg/L, COD ≤ 60mg/L), can not be directly reused.

Example 1

The conditions of the ethylene production unit and various sewage are the same as those of Comparative Example 1.

As shown in Figure 2, the alkali residue wastewater, acid-base wastewater ^and part of the circulating cooling water sewage are cut out from the wastewater treatment system; after wet oxidation treatment of 120,000 m ³ /a The circulating cooling water and sewage of a are mixed, the mixed COD<1000mg/L, the mixed sewage is treated by "BAF + catalytic oxidation + BAF" process, and the effluent is mixed with 300,000 m ³ /a of acid-base wastewater and discharged, and the sewage is discharged COD<60mg/L, the water quality has reached the national first-class environmental discharge standard; Among them, after the first BAF treatment, the B/C<0.3 and COD<200mg/L of the sewage.

Mix 9.38 million m ³ /a wastewater with a salt content of less than 500 mg/L with 1.4 million m ³ /a circulating cooling water system sewage, and then use the BAF process after being treated by the sewage treatment system in Comparative Example 1. The effluent contains Salt content < 1200mg/L, COD < 60mg/L, after sterilization and filtration, all of them are reused in the circulating water system, and the sewage reuse rate is 89.8%.

Comparative example 2

A large-scale petrochemical complex with an oil refining capacity of 10 million t/a and an ethylene production capacity of 800,000 t/a uses surface water with a salt content of 250 mg/L and draws 21.5 million m ³ /a of which 14.5 million is drawn for the circulating cooling water system m ³ /a. The total sewage is 12.5 million m ³ /a, including 14,000 m ³ /a of oil refinery alkali residue wastewater with a salt content of 300,000mg/L and a COD of 150,000-200,000mg/L, and ethylene alkali residue wastewater with a salt content of 45,000mg/L and a COD of 30,000-70,000mg/L 86,000 m ³ /a, 430,000 m ^{3 /a of acid-base wastewater with a salt content of 46,000 mg/L, 3.5 million m 3 /} a of circulating cooling water system sewage with a salt content of 1,800 mg/L, and other waste water with a salt content of less than 500 mg/L The waste water is 8.47 million m ³ /a.

As shown in Figure 3, all the wastewater was mixed and subjected to oil separation-air flotation-biochemical treatment. The salt content of the effluent was 2770mg/L, and the COD was less than 100mg/L. (salt content ≤ 1200mg/L, COD ≤ 60mg/L), cannot be reused directly.

Example 2

The situation of the production device and various sewage is the same as that of Comparative Example 2.

As shown in Figure 4, the oil refining alkali residue wastewater, ethylene alkali residue wastewater, acid-base wastewater and part of the circulating cooling water sewage are cut out from the wastewater treatment system, and the 14,000 m ³ /a treated by "wet oxidation + SBR" Refinery alkali residue wastewater, 86,000 m ³ /a ethylene alkali residue wastewater treated by wet oxidation, and 1.5 million m ³ /a circulating cooling water system sewage with a salt content of 1,800 mg/L were combined, using the "BAF+catalytic oxidation+BAF" process After treatment, the effluent is combined with 430,000 m ³ /a acid-base wastewater and then discharged. The COD of the discharged sewage is less than 60mg/L, and the water quality reaches the national environmental first-level discharge standard; among them, after the first BAF treatment, the B of the sewage /C is 0.1-0.3, COD<200mg/L.

Mix 8.47 million m ³ /a wastewater with a salt content of less than 500 mg/L and 2 million m ³ /a circulating cooling water system sewage. After being treated by the sewage treatment system in Comparative Example 2, the BAF process is used to treat the effluent. Concentration<1200mg/L, COD<60mg/L, after sterilization and filtration, all of them are reused in the circulating water system, and the sewage reuse rate is 83.8%.

Comparative example 3

An ethylene production plant with a production capacity of 300,000 t/a uses surface water with a salt content of 450 mg/L and draws 6.8 million m ³ /a of which the circulating cooling water system draws 4.8 million m ³ /a. The total wastewater discharge is 3.5 million m ³ /a, including 45,000 m ³ /a of alkali slag wastewater containing 30,000 mg/L of salt and 40,000-80,000 mg/L of COD, and 110,000 m ³ /a of acid-base wastewater containing 50,000 mg/L of salt. The sewage of circulating cooling water system with 3200mg/L salt is 800,000 m ³ /a, and other waste water with salt content less than 500 mg/L totals 2.545 million m ³ /a.

As shown in Figure 5, all the waste water was mixed and subjected to oil separation-air flotation-biochemical treatment. The salt content of the effluent was 3050mg/L, and the COD<100mg/L. Both the salt content and the COD amount exceeded the recycled water reuse index. Requirements (salt content ≤ 1200mg/L, COD ≤ 60mg/L), can not be directly reused.

Example 3

The conditions of the ethylene production unit and various sewage are the same as those of Comparative Example 3.

As shown in Figure ⁶ , the alkali slag wastewater, acid-base wastewater and part of the circulating cooling water sewage ^are cut out from the wastewater treatment system; The sewage from the circulating cooling water system is mixed, and the COD after mixing is less than 2000mg/L. The mixed sewage is treated by "BAF + catalytic oxidation + BAF" process, and the effluent is mixed with 110,000 m ³ /a acid-base wastewater and then discharged. The COD of the discharged sewage <60mg/L, the water quality has reached the national environmental first-level discharge standard; Among them, after the first BAF treatment, the B/C of the sewage is 0.1-0.4, and the COD<200mg/L.

The 2.545 million m ³ /a wastewater with a salt content of less than 500mg/L was treated by the sewage treatment system of Comparative Example 3, and then treated with the BAF process. Afterwards, all of them were reused in the circulating water system, and the sewage reuse rate was 72.7%.

Example 4

The situation of the production device and various sewage is the same as that of Comparative Example 2.

As shown in Figure 7, the oil refinery alkali residue wastewater, ethylene alkali residue ^{wastewater ,} acid-base wastewater and part of the circulating cooling water sewage are cut out from the wastewater treatment system. a. Ethylene alkali slag wastewater is mixed. After wet oxidation treatment, it is combined with 1.5 million m ³ /a circulating cooling water system sewage with a salt content of 1,800 mg/L. The "BAF+catalytic oxidation+BAF" process is used for treatment, and the effluent is then mixed with 43 10,000 m ³ /a of acid-base wastewater is combined and discharged, and the COD of the discharged sewage is <60mg/L, and the water quality reaches the national environmental first-class discharge standard; among them, after the first BAF treatment, the B/C of the sewage is <0.4, and the COD< 200mg/L.

Mix 8.47 million m ³ /a wastewater with a salt content of less than 500 mg/L and 2 million m ³ /a circulating cooling water system sewage. After being treated by the sewage treatment system in Comparative Example 2, the BAF process is used to treat the effluent. Concentration<1200mg/L, COD<60mg/L, after sterilization and filtration, all of them are reused in the circulating water system, and the sewage reuse rate is 83.8%.

Claims (12)

1. a treatment for reuse method for oil refining-Ethylene Complex unit sewage, comprising:

(1) refinery basic sewage waste water carries out wet oxidation, SBR process successively;

(2) ethene alkaline sewage is after wet oxidation process, waste water after processing with recirculated cooling water sewer and step (1) mixes, make the COD≤2000mg/L of combined sewage, combined sewage is successively after the first BAF, advanced oxidation and the second BAF process, mix with acidic and alkaline waste water, discharge;

(3) waste water of salts contg≤500mg/L is mixed, successively after oil removal, air supporting, biochemistry, the 3rd BAF process, carry out sterilization and filtration treatment, be then back to recirculating cooling water system.

2. in accordance with the method for claim 1, it is characterized in that, ethene alkaline sewage is after wet oxidation process, and the waste water after processing with recirculated cooling water sewer partly and step (1) mixes; After the waste water of salts contg≤500mg/L mixes with another part recirculated cooling water sewer, then process.

3. in accordance with the method for claim 1, it is characterized in that, in step (2), ethene alkaline sewage is after wet oxidation process, waste water after processing with recirculated cooling water sewer and step (1) mixes, and makes the COD of combined sewage be 1500 ~ 2000mg/L.

4. in accordance with the method for claim 1, it is characterized in that, when carrying out advanced oxidation process to sewage, adopt ozone make oxygenant and regulate the pH value of waste water to be 7 ~ 12.

5. in accordance with the method for claim 1, it is characterized in that, when carrying out advanced oxidation process to sewage, adopt potassium permanganate or chlorine make oxygenant and regulate the pH value of waste water to be 1 ~ 7.

6. in accordance with the method for claim 1, it is characterized in that, when carrying out advanced oxidation process to sewage, adopt hydrogen peroxide, dioxide peroxide or clorox to make oxygenant, regulate the pH value of waste water be 1 ~ 7 and add catalyzer, described catalyzer is selected from transition metal ion Fe ²⁺, Mn ²⁺, Ni ²⁺, Co ²⁺, Cd ²⁺, Cu ²⁺, Ag ⁺, Cr ³⁺and Zn ²⁺in one or more, or be selected from metal oxide MnO ₂, TiO ₂and Al ₂o ₃in one or more.

7. a treatment for reuse method for oil refining-Ethylene Complex unit sewage, comprising:

(1) refinery basic sewage waste water is mixed with ethene alkaline sewage, after wet oxidation process, mix with recirculated cooling water sewer again, make the COD≤2000mg/L of combined sewage, combined sewage is successively after the first BAF, advanced oxidation and the second BAF process, mix with acidic and alkaline waste water, discharge;

(2) waste water of salts contg≤500mg/L is mixed, successively after oil removal, air supporting, biochemistry, the 3rd BAF process, carry out sterilization and filtration treatment, be then back to recirculating cooling water system.

8. in accordance with the method for claim 7, it is characterized in that, refinery basic sewage waste water is mixed with ethene alkaline sewage, after wet oxidation process, mix with the recirculated cooling water sewer of part; After the waste water of salts contg≤500mg/L mixes with another part recirculated cooling water sewer, then process.

9. in accordance with the method for claim 7, it is characterized in that, in step (1), refinery basic sewage waste water is mixed with ethene alkaline sewage, after wet oxidation process, then mix with recirculated cooling water sewer, make the COD of combined sewage be 1500 ~ 2000mg/L.

10. in accordance with the method for claim 7, it is characterized in that, when carrying out advanced oxidation process to sewage, adopt ozone make oxygenant and regulate the pH value of waste water to be 7 ~ 12.

11. in accordance with the method for claim 7, it is characterized in that, when carrying out advanced oxidation process to sewage, adopts potassium permanganate or chlorine make oxygenant and regulate the pH value of waste water to be 1 ~ 7.

12. in accordance with the method for claim 7, it is characterized in that, when carrying out advanced oxidation process to sewage, adopt hydrogen peroxide, dioxide peroxide or clorox to make oxygenant, regulate the pH value of waste water be 1 ~ 7 and add catalyzer, described catalyzer is selected from transition metal ion Fe ²⁺, Mn ²⁺, Ni ²⁺, Co ²⁺, Cd ²⁺, Cu ²⁺, Ag ⁺, Cr ³⁺and Zn ²⁺in one or more, or be selected from metal oxide MnO ₂, TiO ₂and Al ₂o ₃in one or more.