An intermittent sewage treatment system for an oil product terminal

Abstract

The present invention belongs to the technical field of oil terminal sewage treatment, and relates to an intermittent sewage treatment system for oil terminals, which includes a wastewater storage tank, a comprehensive regulation tank, a flotation device, an intermediate water tank, a packed filter, and a middle water tank connected in sequence by pipelines; the packing of the packed filter is a mixture of modified activated carbon and modified walnut shells, and the mass ratio of the modified activated carbon to the modified walnut shells is (0.5 - 2):1. The packing of the packed filter of the present invention can maximize the removal of pollutants such as COD, ammonia nitrogen, phosphorus, and petroleum in the oily sewage to improve the quality of the tail water; moreover, it has high mechanical strength and is not easily worn, can effectively adsorb organic matter in the sewage for a long time, and has a long service life; the present invention adopts an intermittent all-physical treatment system, which reduces the operation load and cost, has low operation and maintenance costs, saves energy and reduces consumption, reduces the use of chemical reagents to the lowest level, and has good treatment effects.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil terminal sewage treatment, and particularly relates to an intermittent sewage treatment system for oil terminals. Background Art

[0002] The main cargo types at oil terminals are crude oil, various refined oils, and edible oils. The main production sewage to be treated in the area is rain sewage, oil tank cleaning water, polluted wastewater, polluted ground flushing water, and laboratory wastewater. The sewage at oil terminals has a high sludge content, a high chemical oxygen demand (COD), a low biochemical oxygen demand (BOD), and poor biodegradability.

[0003] Existing packed filters for treating oil terminal sewage generally use a single material such as activated carbon or walnut shell as the packing. Activated carbon packing has high adsorption capacity, strong adaptability, small floor area, renewable utilization, and can remove heavy metals, but it has low hardness and is not wear-resistant, there are admixtures that are likely to cause secondary pollution, and the treatment cost is high; although walnut shell packing has high hardness, is wear-resistant, is not easy to rot or agglomerate, and has good chemical stability, it is not easy to treat oily sewage; in order to improve the oil removal effect of walnut shell packing, some inventors have carried out modification treatment on walnut shells, such as Chinese invention patents CN 106422520 B and CN105498358 B, but the treatment of pollutants in oily sewage is not comprehensive enough, and its performance still needs to be further improved. Also, since the wastewater treatment volume is affected by the amount of rainfall, it is not suitable for continuous sewage treatment.

[0004] Therefore, it is still necessary to further improve the performance of the packing of the packed filter, adopt an intermittent sewage treatment system, reduce the operation load and cost, reduce the operation and maintenance costs, save energy and reduce consumption, and reduce the usage amount of chemical reagents, etc. Summary of the Invention

[0005] In view of the above-mentioned prior art, the present invention provides an intermittent sewage treatment system for oil terminals, and the specific technical solution is as follows:

[0006] An intermittent sewage treatment system for oil terminals includes a wastewater storage tank, a comprehensive regulation tank, a flotation device, an intermediate water tank, a packed filter, and a middle water tank, which are sequentially connected by pipelines;

[0007] The packing of the packed filter is a mixture of modified activated carbon and modified walnut shell, and the mass ratio of the modified activated carbon to the modified walnut shell is (0.5 - 2):1;

[0008] The modified activated carbon is obtained by subjecting activated carbon particles to calcination treatment, acetic acid treatment, polyaluminum sulfate treatment, and potassium hydrogen phthalate treatment; the modified walnut shell is obtained by subjecting walnut shell particles to ion water boiling treatment, calcination treatment, sodium hypochlorite treatment, and treatment with a mixed solution of polyacrylamide and ferric trichloride.

[0009] The waste water storage tank of the present invention is used to store the cleaning water of oil tanks, polluted waste water, polluted ground flushing water, laboratory waste water, etc., which plays the role of regulating water volume and balancing water quality; the sewage in the waste water storage tank is discharged into the comprehensive regulation tank for physical precipitation and further regulation, and the regulated sewage enters the air flotation device; the air flotation device mainly removes suspended solids and organic matter in the sewage, so as to achieve the purpose of purifying water, and the treated sewage enters the intermediate water tank; the intermediate water tank plays the role of balancing water volume, and then the sewage enters the packing filter; the packing filter deeply adsorbs, reacts and filters pollutants such as COD, ammonia nitrogen and total phosphorus in the oily sewage, and can be used in single-stage or double-stage series according to water quality requirements; the water discharged from the packing filter enters the intermediate water tank, and after being detected to meet the standards, it is discharged or reused.

[0010] The modified activated carbon of the present invention has a larger porosity and specific surface area, and more adsorption sites. By increasing the surface oxygen-containing functional groups and introducing phenyl groups, the adsorption capacity of aromatic organic compounds in sewage is improved, and the COD in sewage is further reduced; the modified walnut shell is more porous and has stronger adsorption. By adding hydrophilic groups and firmly binding with organic matter in sewage through hydrogen bonds, the adsorption effect of hydrophilic organic matter-based heavy metal ions in sewage is significantly improved. Using ferric chloride modification can improve the sulfur adsorption effect of modified walnut shell. The modified filler obtained by mixing and processing the modified activated carbon and walnut shell after modification has strong adsorption capacity, compressive capacity, stable chemical properties (not easily dissolved in acid and alkali solutions), high hardness, good wear resistance, good hydrophilicity, oil immersion resistance, and can be backwashed and regenerated, and does not need to be replaced during long-term use, and has strong adsorption and pollution interception capacity (adsorption rate 25-53%); moreover, the specific gravity of the modified filler of the present invention is slightly greater than that of water, and backwashing and regeneration are convenient. Its biggest feature is that it directly uses the water before filtration for backwashing, and does not require the aid of air source and additional chemical agents, with low operating cost, convenient management, low backwashing intensity, good effect, the filter material is not easy to rot, and is durable.

[0011] Further, the preparation method of the modified activated carbon includes the following steps:

[0012] A1. Under nitrogen protection, calcine activated carbon particles with a mesh size of 100-150 at 300-400 °C for 2-4 hours;

[0013] A2. Put the calcined activated carbon particles into acetic acid, stir at 40-50 °C for 2.5-3.5 hours and then filter, and dry to constant weight in a vacuum drying oven;

[0014] A3. Put the activated carbon particles treated in step A2 into a polyaluminum sulfate solution with a concentration of 6-10 wt%, stir at 40-50 °C for 2.5-3.5 hours and then filter, and dry to constant weight in a vacuum drying oven;

[0015] A4. Put the activated carbon particles after the treatment in step A3 into a potassium hydrogen phthalate solution with a concentration of 0.1 mol / L, perform ultrasonic treatment for 2 - 3 hours under the condition of 40 - 50 °C, then filter, and dry to constant weight in a vacuum drying oven.

[0016] Furthermore, the preparation method of the modified walnut shell includes the following steps:

[0017] B1. Add the walnut shell particles crushed to 100 - 150 meshes into boiling deionized water, heat to boil for 50 - 70 minutes; then under the protection of nitrogen, calcine the walnut shell particles at 300 - 400 °C for 2 - 4 hours;

[0018] B2. Put the calcined walnut shell particles into a sodium hypochlorite solution with a concentration of 8 - 12 wt%, perform ultrasonic treatment for 2 - 3 hours under the condition of 40 - 50 °C, then filter, and dry to constant weight in a vacuum drying oven;

[0019] B3. Put the walnut shell particles after the treatment in step B2 into a mixed solution of polyacrylamide with a concentration of 0.5 - 1.5 wt‰ and ferric trichloride with a concentration of 0.1 - 0.2 mol / L, mix and stir at room temperature for 1.5 - 3.5 hours, filter, and dry to constant weight in a vacuum drying oven.

[0020] Furthermore, an electric valve is provided on the pipeline between the wastewater storage tank and the comprehensive regulation tank; lifting pumps are provided between the comprehensive regulation tank and the air flotation device, between the air flotation device and the intermediate water tank, and inside the intermediate water tank.

[0021] Furthermore, a floating oil collector is arranged inside the wastewater storage tank to collect the floating oil on the surface clean.

[0022] Furthermore, a mechanical grille is provided at the water inlet of the comprehensive regulation tank.

[0023] The mechanical grille mainly intercepts larger suspended solids and floating objects in the production and domestic sewage, which is beneficial to protecting the water pump, preventing the water pump and the subsequent pipeline system from being blocked, and reducing the working load of the subsequent treatment device.

[0024] Furthermore, the air flotation device includes a contact chamber, an air flotation tank, a water pump, a dissolved air tank, a dissolved air release device, a dissolved air pump, and a skimmer;

[0025] The contact chamber is arranged at the bottom of the air flotation tank. The water pump is connected to the dissolved air pump, the dissolved air tank, and the dissolved air release device in sequence through pipelines. The dissolved air release device is located in the contact chamber; the skimmer is located at the upper part of the air flotation tank.

[0026] The sewage discharged from the wastewater storage tank enters the contact chamber after adding chemicals in the comprehensive regulation tank; the water pressurized by the water pump is sent into the dissolved air tank by the dissolved air pump, where it is mixed with compressed air to form dissolved air water. Then, the dissolved air water is transported to the contact chamber through a pipeline and meets the treated water after reacting with the added chemicals in the contact chamber. Due to the sudden pressure drop through the dissolved air release device, gas escapes from the water to form a large number of microbubbles. The flocs generated after the coagulation reaction of the treated water after adding chemicals are adhered by the bubbles, causing the overall specific gravity of the impurity flocs to be less than that of water, and floating to the water surface by buoyancy, thus achieving solid-liquid separation. The scum formed on the liquid surface of the air flotation tank is periodically scraped off by the skimmer to remove suspended solids and organic matter in the water, thereby achieving the purpose of purifying water.

[0027] Further, the packing filter is of a vertical cylindrical structure.

[0028] Further, the drying temperature in the vacuum drying oven is 30 - 45 °C.

[0029] The beneficial effects of the present invention are as follows:

[0030] In the present invention, activated carbon and walnut shells are modified and then mixed as the packing of the packing filter. The modified activated carbon and modified walnut shells complement each other, maximizing the removal of pollutants such as COD, ammonia nitrogen, phosphorus, and petroleum in the oily sewage, improving the quality of the tail water, and enabling the tail water to be more widely applied; and it has high mechanical strength, is not easily worn, can effectively adsorb organic matter in the sewage for a long time, and still has good effects after intermittent operation for a cumulative 1000 h, with a long service life.

[0031] The present invention adopts an intermittent all-physical treatment system, reducing the operation load and cost, having low operation and maintenance costs, energy-saving and consumption-reducing, reducing the usage amount of chemical reagents to the minimum, and having good treatment effects. Specific Embodiments

[0032] The principles and features of the present invention are described below in conjunction with embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0033] Embodiment 1:

[0034] An intermittent sewage treatment system for an oil terminal includes a wastewater storage tank, a comprehensive regulation tank, an air flotation device, an intermediate water tank, a packing filter, and a middle water tank connected in sequence by pipelines;

[0035] An electric valve is provided on the pipeline between the wastewater storage tank and the comprehensive regulation tank; a lift pump one is provided between the comprehensive regulation tank and the air flotation tank; a lift pump two is provided between the air flotation device and the intermediate water tank; and a lift pump three is provided in the intermediate water tank;

[0036] Among them, a floating oil collector is arranged in the wastewater storage tank; a mechanical grille is provided at the water inlet of the comprehensive regulation tank; the air flotation device includes a contact chamber, an air flotation tank, a water pump, a dissolved air tank, a dissolved air pump, and a skimmer; the contact chamber is arranged at the bottom of the air flotation tank, and the water pump is sequentially connected to the dissolved air pump, the dissolved air tank, and the contact chamber through pipelines; the skimmer is located at the upper part of the air flotation tank; the packing filter is of a vertical cylindrical structure. The packing of the packing filter is a mixture of modified activated carbon and modified walnut shell, and the mass ratio of the modified activated carbon to the modified walnut shell is 1.5:1;

[0037] The preparation method of the modified activated carbon includes the following steps:

[0038] A1. Under nitrogen protection, calcine the activated carbon particles of 100 meshes at 350 °C for 3 hours;

[0039] A2. Put the calcined activated carbon particles into acetic acid, stir for 3 hours at 45 °C and then filter, and dry to constant weight at 35 °C in a vacuum drying oven;

[0040] A3. Put the activated carbon particles treated in step A2 into a polyaluminum sulfate solution with a concentration of 8 wt%, stir for 3 hours at 45 °C and then filter, and dry to constant weight at 35 °C in a vacuum drying oven;

[0041] A4. Put the activated carbon particles treated in step A3 into a potassium hydrogen phthalate solution with a concentration of 0.1 mol / L, carry out ultrasonic treatment for 2.5 hours at 45 °C and then filter, and dry to constant weight at 35 °C in a vacuum drying oven;

[0042] The preparation method of the modified walnut shell includes the following steps:

[0043] B1. Add the walnut shell particles crushed to 100 meshes into boiling deionized water, heat to boiling for 50 - 70 minutes; then under nitrogen protection, calcine the walnut shell particles at 350 °C for 3 hours;

[0044] B2. Put the calcined walnut shell particles into a sodium hypochlorite solution with a concentration of 10 wt%, carry out ultrasonic treatment for 2.5 hours at 45 °C and then filter, and dry to constant weight at 35 °C in a vacuum drying oven;

[0045] B3. Put the walnut shell particles treated in step B2 into a mixed solution of 1 wt‰ of polyacrylamide and 0.2 mol / L of ferric chloride, mix and stir at room temperature for 2 hours, filter and dry to constant weight at 35 °C in a vacuum drying oven.

[0046] Using the above intermittent sewage treatment system for oil product terminals to treat the production sewage of oil product terminals, it includes the following steps:

[0047] (1) Sewage enters the wastewater storage tank: The sewage from the terminal production enters the wastewater storage tank, and a floating oil collector is installed in the wastewater storage tank to collect the floating oil on the surface of the wastewater storage tank.

[0048] (2) Treatment in the comprehensive regulation tank: The sewage is discharged from the wastewater storage tank to the comprehensive regulation tank through an electric valve. The mechanical grille intercepts larger suspended solids and floating objects in the sewage; the mechanical grille is cleared of slag 2 - 3 times a day to ensure smooth water inlet.

[0049] (3) Treatment by the air flotation device: After adding chemicals, the sewage enters the contact chamber; the water pressurized by the water pump is sent into the dissolved air tank by the dissolved air pump, where it is mixed with compressed air to form dissolved air water. Then, the dissolved air water is transported to the contact chamber through a pipeline and meets the treated water after reacting with the added chemicals in the contact chamber. Due to the sudden pressure reduction through the dissolved air release device, gas escapes from the water to form a large number of micro - bubbles. The flocs generated after the coagulation reaction of the treated water after adding chemicals are adhered by the bubbles, causing the overall specific gravity of the impurity flocs to be less than that of water, and relying on buoyancy to float to the water surface, thus achieving solid - liquid separation. The floating scum formed on the liquid surface is periodically scraped out by the skimmer to remove suspended solids and organic matter in the water, thereby achieving the purpose of purifying water.

[0050] Among them, the intake air flow of the dissolved air pump is about 10% of the water output and the water output is about 35% of the treated water volume, and the outlet pressure is about 0.4 MPa; the working pressure of the dissolved air tank is 3 kg / cm 2 , the designed reflux ratio is 35%, and the total residence time is 45 min; the flow rate of the dissolved air pump is 25 t / h, the head is 50 m, and the power is 7.5 KW. When the pressure in the dissolved air tank > 0.30 MPa, the outlet valve of the dissolved air tank is opened, and the reflux amount is adjusted, generally 20% of the treated water volume. At the same time, the driving device is started, and the effect of the dissolved air water in the air flotation tank is observed. It is normal when the water distribution area is milky white and there are no large bubbles.

[0051] (4) The effluent enters the intermediate water tank: The intermediate water tank functions to regulate the water volume in the process. The outlet valve of the third lift pump is adjusted to an outlet flow rate of about 10 t / h, and the third lift pump in the intermediate water tank lifts the sewage into the packed filter.

[0052] (5) Treatment by the packed filter: Using the principle of filtration separation, the packed filter deeply adsorbs, reacts, and filters pollutants such as COD, ammonia nitrogen, and total phosphorus in the oily sewage.

[0053] Among them, the equipment specifications of the packing filter are as follows: φ1600×4620; equipment type: vertical cylindrical container; equipment diameter: 1600 mm; operating flow rate: 15 m / h; water treatment capacity: 30 m³ / h; filter media height: 1600 mm; design pressure: 0.6 MPa; test pressure: 0.75 MPa; working temperature: 4 - 50 °C; mixer power: 2.2 KW; water backwashing intensity: 4 - 15 L / (m 2 •s); backwashing expansion height: 1600 mm.

[0054] (6)The effluent filtered by the packing filter enters the intermediate water tank, and the treated water is collected for reusing as intermediate water.

[0055] Example 1: The indicators of the oil terminal production sewage before and after treatment are shown in Table 1:

[0056] Table 1 The indicators of the oil terminal production sewage before and after treatment

[0057]

[0058] Example 2:

[0059] The packing of the packing filter is a mixture of modified activated carbon and modified walnut shells, and the mass ratio of the modified activated carbon to the modified walnut shells is 1:1.5; other conditions are the same as those in Example 1 and will not be elaborated here. The indicators of the oil terminal production sewage after treatment in Example 2 are shown in Table 2:

[0060] Table 2 The indicators of the oil terminal production sewage after treatment

[0061]

[0062] Comparative Example 1:

[0063] The packing of the packing filter is a mixture of unmodified activated carbon and unmodified walnut shells, and the mass ratio of the unmodified activated carbon to the unmodified walnut shells is 1.5:1; other conditions are the same as those in Example 1 and will not be elaborated here. The indicators of the oil terminal production sewage after treatment in Comparative Example 1 are shown in Table 3:

[0064] Table 3 The indicators of the oil terminal production sewage after treatment

[0065]

[0066] Comparative Example 2:

[0067] The packing of the packing filter is a mixture of unmodified activated carbon and unmodified walnut shells, and the mass ratio of the unmodified activated carbon to the unmodified walnut shells is 1:1.5; other conditions are the same as those in Example 1 and will not be elaborated here. The indicators of the oil terminal production sewage after treatment in Comparative Example 2 are shown in Table 4:

[0068] Table 4 Various indicators of the produced sewage treatment at the oil product terminal

[0069]

[0070] Comparative Example 3:

[0071] The filler of the filler filter is modified walnut shell; the others are the same as in Example 1 and will not be elaborated here. The various indicators of the produced sewage treatment at the oil product terminal in Comparative Example 3 are shown in Table 5:

[0072] Table 5 Various indicators of the produced sewage treatment at the oil product terminal

[0073]

[0074] Comparative Example 4:

[0075] The filler of the filler filter is modified activated carbon; the others are the same as in Example 1 and will not be elaborated here. The various indicators of the produced sewage treatment at the oil product terminal in Comparative Example 4 are shown in Table 6:

[0076] Table 6 Various indicators of the produced sewage treatment at the oil product terminal

[0077]

[0078] The removal rates of each detection item in Examples 1-2 and Comparative Examples 1-4 are shown in Table 7:

[0079] Table 7 Removal rates of each detection item

[0080]

[0081] It can be seen from the removal rates of the parameters in Examples 1 and 2 that they are all above 95%. It can be seen that the treatment effect of the oil-containing sewage by using the mixed filler of modified activated carbon and modified walnut shell in the present invention is obvious. Compared with Example 2, the mass fraction of the added modified activated carbon in Example 1 is larger. From the removal rates of each index, the effect of Example 1 is better.

[0082] Comparative Example 1 treats the same wastewater as in Example 1, and replaces the mixed filter material of modified activated carbon and modified walnut shell with the mixed filter material of unmodified ordinary activated carbon and walnut shell; it can be seen from the removal rates of the parameters in Example 1 and Comparative Example 1 that the removal rates of the two indicators of suspended matter and chromaticity in Comparative Example 1 are okay, but the removal rates of other indicators are all lower than 58.7%. It can be seen that the treatment effect of the sewage is better after the filter material in the filter is modified in the present invention.

[0083] Comparative Example 2 treated the same wastewater as Example 2, and replaced the mixed filter material of modified activated carbon and modified walnut shell with an unmixed ordinary activated carbon and walnut shell filter material; from the removal rates of various parameters in Example 2 and Comparative Example 2, it can be seen that for the two indicators of suspended solids and chromaticity in Comparative Example 2, they are acceptable, but the removal rates of other indicators are all lower than 57.9%. It can be seen that after the filter material in the filter of the present invention is modified, the treatment effect on sewage is better.

[0084] Comparative Example 3 treated the same wastewater as Examples 1 and 2. Comparative Example 3 only used modified walnut shell as the filtering and adsorbing material of the filter; from the removal rates of various parameters in Examples 1 and 2 and Comparative Example 3, it can be seen that for Comparative Example 3, the removal rates of other pollutant indicators except the chromaticity index are all lower than 85.83%. It can be seen that using only modified walnut shell as the filter material has a less obvious treatment effect on sewage than mixing and matching modified activated carbon and modified walnut shell according to Examples 1 and 2.

[0085] Comparative Example 4 treated the same wastewater as Examples 1 and 2. Comparative Example 4 only used modified activated carbon as the filtering and adsorbing material of the filter; from the removal rates of various parameters in Examples 1 and 2 and Comparative Example 4, it can be seen that for Comparative Example 4, the removal rates of other pollutant indicators except the chromaticity index are all lower than 85%. It can be seen that using only modified activated carbon as the filter material has a less obvious treatment effect on sewage than mixing and matching modified activated carbon and modified walnut shell according to Examples 1 and 2.

[0086] The detection methods, bases and instruments used are shown in Table 8:

[0087] Table 8 Detection methods, bases and instruments used

[0088]

[0089] In the present invention, activated carbon and walnut shell are modified and then mixed and processed as the filler of the packed filter. The modified activated carbon and the modified walnut shell complement each other, and can remove pollutants such as COD, ammonia nitrogen, phosphorus, and petroleum in the oily sewage to the greatest extent, so as to improve the quality of the tail water and enable the tail water to be more widely used. The addition of modified walnut shell solves the disadvantages of the modified activated carbon filter material with poor mechanical strength, easy abrasion and structural damage, and can effectively adsorb organic matter in sewage for a long time. The mixing of the two modified filter materials still has a good effect after 1000h of intermittent operation in total, and the service life is relatively long. The present invention adopts an intermittent all-physical treatment system, which reduces the operation load and cost, has low operation and maintenance costs, saves energy and reduces consumption, reduces the usage amount of chemical reagents to the lowest level, and has good treatment effects.

[0090] The foregoing are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An intermittent sewage treatment system for an oil terminal, characterized in that: It includes a wastewater storage tank, a comprehensive regulating tank, an air flotation device, an intermediate water tank, a filler filter and a middle water tank which are sequentially connected by pipelines; The filler of the filler filter is a mixture of modified activated carbon and modified walnut shell, and the mass ratio of the modified activated carbon to the modified walnut shell is (0.5-2):1; The preparation method of the modified activated carbon comprises the following steps: A1. Under nitrogen protection, calcine the activated carbon particles of 100-150 mesh at 300-400℃ for 2-4 hours; A2. Place the calcined activated carbon particles in acetic acid, stir at 40-50°C for 2.5-3.5 hours, filter, and dry in a vacuum drying oven to constant weight; A3, placing the activated carbon particles treated in step A2 into a 6-10wt% polyaluminium sulfate solution, stirring at 40-50°C for 2.5-3.5 hours, filtering, and drying in a vacuum drying oven to constant weight; A4, placing the activated carbon particles treated in step A3 into a 0.1 mol / L potassium hydrogen phthalate solution, ultrasonically treating at 40-50°C for 2-3 hours, filtering, and drying in a vacuum drying oven to constant weight; The preparation method of the modified walnut shell comprises the following steps: B1. Add walnut shell particles crushed to 100-150 mesh into boiling deionized water and heat to boil for 50-70 minutes; then calcine the walnut shell particles at 300-400° C. for 2-4 hours under nitrogen protection; B2. Place the calcined walnut shell particles into a sodium hypochlorite solution with a concentration of 8-12 wt%, ultrasonically treat at 40-50° C. for 2-3 hours, filter, and dry in a vacuum drying oven to constant weight; B3. Place the walnut shell particles treated in step B2 into a mixed solution of 0.5-1.5 wt‰ polyacrylamide and 0.1-0.2 mol / L ferric chloride, stir at room temperature for 1.5-3.5 hours, filter and dry in a vacuum drying oven to constant weight.

2. The intermittent sewage treatment system for oil terminal according to claim 1 is characterized in that: An electric valve is provided on the pipeline between the wastewater storage tank and the comprehensive regulating tank; a lifting pump is provided between the comprehensive regulating tank and the air flotation device, between the air flotation device and the intermediate water tank, and inside the intermediate water tank.

3. The intermittent sewage treatment system for oil terminal according to claim 2 is characterized in that: A buoy-type oil collector is arranged in the wastewater storage tank.

4. The intermittent sewage treatment system for oil terminal according to claim 1 is characterized in that: The water inlet of the comprehensive regulating tank is provided with a mechanical grille.

5. The intermittent sewage treatment system for oil terminal according to claim 1 is characterized in that: The air flotation device comprises a contact chamber, an air flotation tank, a water pump, an air dissolving tank, an air dissolving releaser, an air dissolving pump, and a slag skimmer; The contact chamber is arranged at the bottom of the flotation tank, the water pump is sequentially connected to the dissolved air pump, the dissolved air tank and the dissolved air releaser through pipelines, and the dissolved air releaser is located in the contact chamber; the skimmer is located at the upper part of the flotation tank.

6. The intermittent sewage treatment system for oil terminal according to claim 1 is characterized in that: The packing filter is a vertical cylindrical structure.

7. The intermittent sewage treatment system for oil terminal according to claim 1 is characterized in that: The drying temperature in the vacuum drying oven is 30-45°C.

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