CN111072217A

CN111072217A - Method for advanced treatment and recycling of saliferous oil refining wastewater

Info

Publication number: CN111072217A
Application number: CN201811227964.4A
Authority: CN
Inventors: 颜家保; 夏正海; 张建文; 汪坤; 刘斯洋
Original assignee: China Petroleum and Chemical Corp; Wuhan University of Science and Technology WHUST
Current assignee: China Petroleum and Chemical Corp; Wuhan University of Science and Technology WHUST
Priority date: 2018-10-22
Filing date: 2018-10-22
Publication date: 2020-04-28

Abstract

The invention discloses a method for advanced treatment and reuse of salt-containing oil refining wastewater. The pre-treated salt-containing oil refining wastewater first flows into an anoxic reactor for 8-10 hours, and then enters a membrane bioreactor for 15-20 hours. Return to the anoxic reactor, and the other part flows into the coagulation and sedimentation tank; add coagulant to the coagulation sedimentation tank for coagulation and sedimentation; after coagulation and sedimentation, the effluent is filtered by a multi-media filter and then enters the ozone catalytic oxidation tower. It reacts with ozone under the catalytic action of the wut‑5 catalyst for 12 to 17 minutes, and flows into the intermediate pool after the reaction; the effluent from the intermediate pool enters the reverse osmosis membrane module, and the concentrated reverse osmosis water is discharged up to the standard after electrocatalytic oxidation. The produced water is reused as supplementary water or desalinated water for circulating water. The invention has the advantages of simple process, compact equipment, low degree of membrane pollution, stable process operation, good quality of recycled water and the like.

Description

Method for advanced treatment and recycling of saliferous oil refining wastewater

Technical Field

The invention relates to a method for advanced treatment and recycling of saliferous oil refining wastewater, and belongs to the technical field of advanced treatment of oil refining wastewater.

Background

At present, the crude oil processing capacity of China is nearly 3 hundred million tons/year, the oil refining demand is continuously increased along with the high-speed development of economy, a large amount of salt-containing wastewater is generated in the oil refining and processing process, the part of wastewater mainly comprises atmospheric and vacuum distillation electrodeionization water, high-salt-containing waste alkali liquor generated in the ethylene production process, phenol acetone high-salt-containing sewage and the like, the salt content of the wastewater is high, the concentration of organic pollutants is high, for example, COD in the high-salt wastewater of Wuhan petrochemical is as high as 950 mg/L-1350 mg/L, in addition, the salt-containing wastewater generated in the oil refining process has large water quality fluctuation and high treatment difficulty, although the discharge standard can be reached by adopting a combined process of ozone oxidation and aeration, the Cl contained in the wastewater can reach^-、SO₄ ^2-、Ca²⁺、Mg²⁺When the salt concentration is high, the risk of corrosion and scaling exists and the salt can not be recycled.

From 7 months and 1 day in 2017, the existing petrochemical enterprises begin to execute a new emission standard for petroleum refining industry pollutants (GB31570-2015), which stipulates that the upper limit of the water discharge of crude oil of a processing unit is 0.5m³The upper limit of the water discharge amount of the area with poor environment bearing capacity and ecological weakness is 0.4m³And/t, if the salt-containing oil refining wastewater is only treated to reach the standard and is discharged without being recycled, the water consumption requirement of a new standard is difficult to meet.

At present, the petrochemical oil refining enterprise wastewater in China has two modes, one mode is to separately treat the oil-containing wastewater and the high-salt-content wastewater, the other mode is to treat the oil-containing wastewater and the high-salt-content wastewater together, and the development trend is that the oil-containing oil refining wastewater is relatively well treated in the former mode, so most of the part of the oil refining enterprise wastewater is recycled, but the salt-content wastewater is mainly discharged after being subjected to advanced treatment and reaches the standard without being recycled.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for advanced treatment and recycling of salt-containing oil refining wastewater, which is used for completely removing organic pollutants in the salt-containing oil refining wastewater by utilizing membrane bioreaction, coagulation and ozone catalytic oxidation, relieving membrane pollution from the source, prolonging the backwashing period and the service life of a membrane, overcoming the technical bottleneck that membrane pollution frequently occurs when reverse osmosis is applied to an oil refining wastewater recycling process, and further realizing long-period stable operation of a wastewater recycling device and recycling of the salt-containing oil refining wastewater. The method has the advantages of simple process, compact equipment, low membrane pollution degree, stable process operation and good quality of recycled water.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for advanced treatment and recycling of saline oil refining wastewater comprises the following steps:

(1) and (3) anoxic treatment: enabling the pretreated saliferous oil refining wastewater to flow into an anoxic reactor through a lift pump, and staying in the anoxic reactor for 8-10 hours to complete anoxic treatment;

(2) membrane biological treatment: the effluent obtained after the anoxic treatment in the step (1) enters a membrane bioreactor, stays in the membrane reactor for 15-20 h, and then membrane biological treatment is completed; returning a part of effluent obtained after membrane biological physiology to the anoxic reactor to continue anoxic treatment according to the operation of the step (1), and flowing the other part of effluent into a coagulation sedimentation tank;

(3) coagulating sedimentation treatment: after effluent obtained after the membrane biological treatment in the step (2) enters a coagulating sedimentation tank, adding a coagulant into the coagulating sedimentation tank for coagulation reaction; the addition amount of the coagulant is 15-20 mg/L, and the coagulation reaction and precipitation time is 20-30 min;

(4) ozone catalytic oxidation treatment: filtering effluent obtained after the coagulating sedimentation treatment in the step (3) by using a multi-medium filter, then feeding the effluent into an ozone catalytic oxidation tower filled with wut-5 type catalyst, and carrying out catalytic oxidation reaction with ozone under the catalytic action of wut-5 type catalyst, wherein the reaction time is 12-17 min;

(5) reverse osmosis treatment: the effluent obtained after the catalytic oxidation treatment of the ozone in the step (3) flows into an intermediate water tank, the effluent of the intermediate water tank is lifted by a high-pressure pump and flows into a cartridge filter for filtration treatment, and then is lifted by the high-pressure pump and flows into a reverse osmosis water purifier for reverse osmosis treatment, and concentrated water and produced water are obtained after the reverse osmosis treatment; the concentrated water is discharged after reaching standards after the electrocatalytic oxidation reaction is carried out by the electrocatalytic oxidation reactor, and the produced water is recycled as make-up water or desalted water of circulating water.

In the above technical scheme, in the step (1), the pretreatment refers to that the salt-containing oil refining wastewater is subjected to oil removal and two-stage air flotation treatment in sequence according to a traditional method.

In the technical scheme, in the step (2), the reflux ratio is 200-300%.

In the above technical scheme, in the step (3), the coagulant is a composite coagulant obtained by compounding an inorganic coagulant and an organic coagulant; preferably, the composite coagulant is obtained by compounding polysilicate aluminum ferric sulfate (PSAFS) and Polyacrylamide (PAM), wherein the PAM accounts for 8-12 wt% of the total mass of the composite coagulant.

In the technical scheme, in the step (4), the effective volume of the wut-5 type catalyst filled in the ozone catalytic oxidation tower is 20-30 vol%, and the adding amount of ozone is 25-35 mg/L.

In the technical scheme, in the step (4), the wut-5 type catalyst is a spherical particle solid catalyst, and the particle size is 3-5 mm; the active component and the carrier are used as raw materials, and the active component and the carrier are granulated by a traditional disc granulation method and then sintered for 15-35 min at 1050-1150 ℃.

In the technical scheme, the active component is a mixture formed by mixing any two or more of manganese sulfate, manganese acetate, potassium permanganate, ferric nitrate, copper sulfate and titanium dioxide in any proportion, and the total mass percentage of the active component is 5-8 wt%.

In the above technical scheme, the carrier is a mixture of a viscous carrier and other carriers mixed in any proportion, wherein: the viscous carrier is clay; the other carrier is one of fly ash and steel slag or a mixture of the fly ash and the steel slag mixed in any proportion.

The anoxic reactor, the membrane bioreactor, the multi-media filter, the ozone catalytic oxidation tower, the cartridge filter, the reverse osmosis water purifier and the electrocatalytic oxidation reactor are all traditional equipment sold in the field, and can be operated according to the conventional operation method in the field if the special requirements of the anoxic reactor, the membrane bioreactor, the multi-media filter, the ozone catalytic oxidation tower, the cartridge filter, the reverse osmosis water purifier and the electrocatalytic oxidation reactor are not met.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following positive effects:

(1) the invention replaces the traditional activated sludge bioreactor with a Membrane Bioreactor (MBR), has high sludge concentration, long sludge age, good impact load resistance, stable operation and high organic pollutant removal efficiency.

(2) The method fully exerts destabilization coagulation of the inorganic coagulant and bridging flocculation coupling action of the organic flocculant by adding the composite inorganic/organic coagulant, further removes residual organic matters and a small amount of suspended matters in the wastewater by filtering through the multi-medium filter, is favorable for exerting catalytic effect of catalytic oxidation of ozone, and utilizes the catalytic action of the high-activity wut-5 type ozone catalyst to mineralize the organic matters in the wastewater more completely.

(3) The method utilizes membrane biological reaction, coagulation and ozone catalytic oxidation to remove organic pollutants in the saliferous oil refining wastewater more completely, reduces membrane pollution from the source, prolongs the backwashing period and the service life of the membrane, overcomes the technical bottleneck that membrane pollution is frequently generated when reverse osmosis is applied to the oil refining wastewater recycling process, realizes long-period stable operation of a wastewater recycling device, and has high reverse osmosis desalination rate and good recycled water quality. After the pretreated saliferous oil refining wastewater is treated by the method, the quality of the obtained reuse water is as follows: 13-25 mg/L of COD, 0.2-0.5 mg/L of petroleum, 130-165 mu S/cm of conductivity, 13-25 mg/L of total hardness and 15-25 mg/L of chloride ions, which shows that the water quality of the reuse water obtained by the method completely meets the water quality standard requirements of the make-up water and the desalted water of the circulating water.

Therefore, the invention has the advantages of simple process, compact equipment, low membrane pollution degree, stable process operation, good quality of recycled water and the like.

Drawings

FIG. 1 is a schematic process flow diagram of the method for advanced treatment and reuse of oil refining wastewater containing salt according to the present invention.

Detailed Description

The following detailed description of the embodiments of the present invention is provided, but the present invention is not limited to the following descriptions:

in the following examples, the pretreatment refers to that the salt-containing oil refining wastewater is sequentially subjected to oil removal and two-stage air flotation treatment according to a conventional method, and details are not repeated in the examples.

Example 1:

(1) and (3) anoxic treatment: the pretreated saliferous oil refining wastewater flows into the anoxic reactor through the lift pump and stays for 8 hours;

(2) membrane biological treatment: allowing effluent obtained after the anoxic treatment in the step (1) to enter a membrane bioreactor, staying for 15h, refluxing one part of the effluent of the membrane bioreactor to the anoxic reactor, wherein the reflux ratio is 200%, and allowing the other part of the effluent to flow into a coagulation tank;

(3) coagulating sedimentation treatment: after effluent obtained after the membrane biological treatment in the step (2) enters a coagulating sedimentation tank, adding a coagulant into the coagulating sedimentation tank for coagulating sedimentation, wherein the adding amount of the coagulant is 15mg/L, and performing coagulation reaction and sedimentation for 20 min;

(4) ozone catalytic oxidation treatment: filtering effluent obtained after the coagulating sedimentation treatment in the step (3) by using a multi-medium filter, then feeding the effluent into an ozone catalytic oxidation tower filled with wut-5 type catalyst, and carrying out catalytic oxidation reaction with ozone under the catalytic action of wut-5 type catalyst, wherein the reaction time is 12 min; the effective volume of the wut-5 type catalyst filled in the ozone catalytic oxidation tower is 20 vol%, and the adding amount of ozone is 25 mg/L;

The coagulant in the embodiment is a composite medicament of polysilicate aluminum ferric sulfate (PSAFS) and Polyacrylamide (PAM), wherein the PAM accounts for 8 wt% of the total mass of the composite coagulant;

the wut-5 type catalyst in the embodiment is a spherical catalysis ceramsite solid catalyst, has the particle size of 3-5 mm, is prepared by granulating an active component and a carrier serving as raw materials by a traditional disc granulation method and sintering the granulated raw materials at a high temperature of 1080 ℃ for 25 min; wherein: the active components of the composite material are manganese sulfate and potassium permanganate, the mass ratio of the manganese sulfate to the potassium permanganate is 2:3, the total mass percentage of the active components is 5 wt%, and the balance is a carrier; the carrier is clay and fly ash, and the mass ratio is 2: 3.

the water quality of the wastewater after the pretreatment of the salt-containing oil refining wastewater and the water quality of the reuse water obtained after the pretreatment of the salt-containing oil refining wastewater and the treatment of the method described in this embodiment are shown in table 1:

TABLE 1 comparison of water quality indexes after treatment by different treatment methods

Example 2:

(1) and (3) anoxic treatment: the pretreated saliferous oil refining wastewater flows into the anoxic reactor through the lift pump and stays for 9 hours;

(2) membrane biological treatment: allowing effluent obtained after the anoxic treatment in the step (1) to enter a membrane bioreactor, staying for 17 hours, allowing one part of the effluent of the membrane bioreactor to flow back to the anoxic reactor, wherein the reflux ratio is 250%, and allowing the other part of the effluent to flow into a coagulation tank;

(3) coagulating sedimentation treatment: after effluent obtained after the membrane biological treatment in the step (2) enters a coagulating sedimentation tank, adding a coagulant into the coagulating sedimentation tank for coagulating sedimentation, wherein the adding amount of the coagulant is 17mg/L, and carrying out coagulation reaction and sedimentation for 25 min;

(4) ozone catalytic oxidation treatment: filtering effluent obtained after the coagulating sedimentation treatment in the step (3) by using a multi-medium filter, then feeding the effluent into an ozone catalytic oxidation tower filled with wut-5 type catalyst, and carrying out catalytic oxidation reaction with ozone under the catalytic action of wut-5 type catalyst, wherein the reaction time is 15 min; the effective volume of the wut-5 type catalyst filled in the ozone catalytic oxidation tower is 25 vol%, and the adding amount of ozone is 30 mg/L;

The coagulant in this embodiment is a composite agent of polysilicate aluminum ferric sulfate (PSAFS) and Polyacrylamide (PAM), wherein the PAM accounts for 10 wt% of the total mass of the composite coagulant.

The wut-5 type catalyst in the embodiment is a spherical catalysis ceramsite solid catalyst, has the particle size of 3-5 mm, is prepared by granulating an active component and a carrier serving as raw materials by a traditional disc granulation method and sintering the granulated raw materials at the high temperature of 1100 ℃ for 20 min; wherein: the active components comprise copper nitrate and copper sulfate, the mass ratio of the copper nitrate to the copper sulfate is 7:13, the total mass percentage of the active components is 6 wt%, and the balance is a carrier; the carrier is clay and steel slag, and the mass ratio is 2: 3.

the water quality of the wastewater after the pretreatment of the salt-containing oil refining wastewater and the water quality of the reuse water obtained after the pretreatment of the salt-containing oil refining wastewater and the treatment of the method described in this embodiment are shown in table 2:

TABLE 2 comparison of water quality indexes after treatment by different treatment methods

Example 3:

(1) and (3) anoxic treatment: the pretreated saliferous oil refining wastewater flows into the anoxic reactor through the lift pump and stays for 10 hours;

(2) membrane biological treatment: allowing effluent obtained after the anoxic treatment in the step (1) to enter a membrane bioreactor, staying for 20 hours, allowing part of the effluent of the membrane bioreactor to flow back to the anoxic reactor, wherein the reflux ratio is 300%, and allowing the other part of the effluent to flow into a coagulation tank;

(3) coagulating sedimentation treatment: after effluent obtained after the membrane biological treatment in the step (2) enters a coagulating sedimentation tank, adding a coagulant into the coagulating sedimentation tank for coagulating sedimentation, wherein the adding amount of the coagulant is 20mg/L, and carrying out coagulation reaction and sedimentation for 30 min;

(4) ozone catalytic oxidation treatment: filtering effluent obtained after the coagulating sedimentation treatment in the step (3) by using a multi-medium filter, then feeding the effluent into an ozone catalytic oxidation tower filled with wut-5 type catalyst, and carrying out catalytic oxidation reaction with ozone under the catalytic action of wut-5 type catalyst, wherein the reaction time is 17 min; the effective volume of the wut-5 type catalyst filled in the ozone catalytic oxidation tower is 30 vol%, and the adding amount of ozone is 35 mg/L;

The coagulant in this embodiment is a composite reagent of polysilicate aluminum ferric sulfate (PSAFS) and Polyacrylamide (PAM), wherein the PAM accounts for 12 wt% of the total mass of the composite coagulant.

The wut-5 type catalyst in the embodiment is a spherical catalysis ceramsite solid catalyst, has the particle size of 3-5 mm, is prepared by granulating an active component and a carrier serving as raw materials by a traditional disc granulation method and sintering the granulated raw materials at a high temperature of 1120 ℃ for 15 min; wherein: the active components comprise manganese sulfate, copper sulfate and titanium dioxide, the mass ratio of the manganese sulfate, the copper sulfate and the titanium dioxide is 5:9:6, the total mass percentage of the active components is 8 wt%, and the balance is a carrier; the carrier is clay, fly ash and steel slag, and the mass ratio is 1: 1: 1.

the water quality of the wastewater after the pretreatment of the salt-containing oil refining wastewater and the water quality of the reuse water obtained after the pretreatment of the salt-containing oil refining wastewater and the treatment of the method described in this embodiment are shown in table 3:

TABLE 3 comparison of water quality indexes after treatment by different treatment methods

	Conventional methods	Method of the present embodiment
			COD	75～110mg/L	13～18mg/L
Petroleum products	1.5～3.5mg/L	0.2～0.4mg/L
			Electrical conductivity of	1500～3500μS/cm	130～155μS/cm
Total hardness	95～200mg/L	13～18mg/L
			Chloride ion	165～250mg/L	15～20mg/L

Compared with the prior art, the specific implementation mode has the following positive effects:

(3) The method utilizes membrane biological reaction, coagulation and ozone catalytic oxidation to remove organic pollutants in the saliferous oil refining wastewater more completely, reduces membrane pollution from the source, prolongs the backwashing period and the service life of the membrane, overcomes the technical bottleneck that membrane pollution is frequently generated when reverse osmosis is applied to the oil refining wastewater recycling process, realizes long-period stable operation of a wastewater recycling device, and has high reverse osmosis desalination rate and good recycled water quality.

Therefore, the specific implementation mode has the advantages of simple process, compact equipment, low membrane pollution degree, stable process operation, good quality of recycled water and the like.

The above examples are only for illustrating the technical concept and features of the present invention, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. a method for advanced treatment and reuse of salt-containing oil refining waste water, is characterized in that, comprises the following steps:

(1) Anoxic treatment: the pretreated salt-containing oil refining wastewater flows into the anoxic reactor through a lift pump, and the anoxic treatment is completed after staying in the anoxic reactor for 8-10 hours;

(2) Membrane biological treatment: the effluent obtained after the anoxic treatment in step (1) enters the membrane bioreactor, and stays in the membrane reactor for 15-20 hours to complete the membrane biological treatment; the effluent obtained after the membrane biological physiology A part is returned to the anoxic reactor and continues to perform anoxic treatment according to the operation of step (1), and the other part flows into the coagulation sedimentation tank;

(3) Coagulation and sedimentation treatment: after the effluent obtained after the membrane biological treatment in step (2) enters the coagulation sedimentation tank, a coagulant is added to the coagulation sedimentation tank for coagulation reaction; The amount is 15～20mg/L, and the coagulation reaction and precipitation time are 20～30min;

(4) Ozone catalytic oxidation treatment: the effluent obtained after the coagulation and precipitation treatment in step (3) is filtered by a multi-media filter and enters the ozone catalytic oxidation tower filled with wut-5 type catalyst. Catalytic oxidation reaction is carried out with ozone under catalytic action, and the reaction time is 12-17 minutes;

(5) Reverse osmosis treatment: the effluent obtained after the ozone catalytic oxidation treatment in step (3) flows into the intermediate pool, and the effluent of the intermediate pool is lifted by the high-pressure pump and flows into the security filter for filtration treatment, and then lifted by the high-pressure pump and flows into Go to the reverse osmosis water purifier for reverse osmosis treatment. After reverse osmosis treatment, concentrated water and product water are obtained; the concentrated water is subjected to electrocatalytic oxidation reaction in the electrocatalytic oxidation reactor and then discharged up to the standard, and the produced water is used as supplementary water or desalination of circulating water. Water reuse.

2 . The method according to claim 1 , wherein, in step (1), the pretreatment refers to that the salt-containing oil refining wastewater is treated by oil separation and two-stage air flotation in turn according to traditional methods. 3 .

3. The method according to claim 1, wherein in step (2), the reflux ratio is 200-300%.

4. The method according to claim 1, characterized in that, in step (3), the coagulant is a composite coagulant, which is a composite coagulation obtained by compounding an inorganic coagulant and an organic coagulant. agent.

5. method according to claim 4 is characterized in that, described coagulant is the composite coagulant obtained after the compounding of polysilicon aluminum ferric sulfate and polyacrylamide, wherein polyacrylamide accounts for the composite coagulant 8-12wt% of the total mass.

6. method according to claim 1, is characterized in that, in step (4), in ozone catalytic oxidation tower, the effective volume of the wut-5 type catalyst of filling is 20～30vol%, and ozone dosage is 25～30vol% 35mg/L.

7. method according to claim 1, is characterized in that, in step (4), described wut-5 type catalyst is spherical particle solid catalyst, and particle diameter is 3～5mm; The raw material is granulated by the traditional disc granulation method and sintered at a high temperature of 1050 to 1150 ° C for 15 to 35 minutes.

8. method according to claim 7, is characterized in that, described active component is any two or two in manganese sulfate, manganese acetate, potassium permanganate, iron nitrate, copper nitrate, copper sulfate, titanium dioxide. The total mass percentage of the active components is 5-8 wt %.

9. The method according to claim 7, wherein the carrier is a mixture of a viscous carrier and other carriers in any proportion, wherein: the viscous carrier is clay; the other carriers are fly ash, steel slag Any one, or a mixture of two in any proportion.