Combined filtering and deoiling equipment for oily sewage treatment

Abstract

The present application belongs to the technical field of oily wastewater treatment equipment, and particularly relates to a combined filter and oil removal equipment for oily wastewater treatment. The equipment comprises coalescing filter cartridges and modified quartz sand fillings arranged in the coalescing filter cartridges, and combines a traditional filling filter with a filter cartridge type coalescing oil removal device to form a structure of 'fillings in filter cartridges'. The present application disperses the filter fillings in the coalescing filter cartridges, effectively avoids the problem of hardening of large filling slabs, improves the stability and service life of the system, and has the functions of efficient oil removal and filtration of suspended solids. The equipment has compact structure, small volume and stable operation, can significantly improve the filtration efficiency and reduce the maintenance frequency, and is suitable for oily wastewater treatment systems with large water quality fluctuations.

Description

Technical Field

[0001] This invention belongs to the technical field of oily wastewater treatment equipment, specifically relating to a combined filtration and oil removal device for treating oily wastewater. Background Technology

[0002] In oily wastewater treatment systems, commonly used oil removal equipment includes packed filter media and cartridge coalescing oil separators. Packed filter media often uses modified silica sand for deep oil removal and suspended solids retention. However, modified silica sand is prone to caking during long-term operation, leading to increased filtration resistance, decreased flow rate, poor backwashing effect, and even requiring shutdown for media replacement, increasing operating and maintenance costs and downtime. Cartridge coalescing oil separators use a special material filter element to coalesce tiny oil droplets into larger droplets, which then float and separate. However, their ability to intercept suspended solids is limited, often requiring pre-filtration equipment.

[0003] In existing technologies, these two types of equipment are mostly used independently or arranged in series, resulting in large footprints, long processes, and frequent maintenance. Especially under conditions of high oil content and high suspended solids, the problem of packing caking becomes more prominent, affecting the long-term stable operation of the system. Therefore, there is an urgent need for an integrated treatment device that can efficiently remove oil while preventing packing caking. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a combined filtration and oil removal device for oily wastewater treatment. This device has a compact structure, strong anti-caking ability, and combines efficient oil removal and filtration functions, making it suitable for oily wastewater treatment in petrochemical and other fields.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a combined filtration and oil removal device for treating oily wastewater, comprising a tank, an inlet pipe, an outlet pipe, and an oil collection chamber disposed on the tank. The tank is provided with a plurality of detachable coalescing filter elements, each of which is filled with filter media. The coalescing filter element includes an outer coalescing layer and an inner mediating cavity. After the wastewater enters the shell through the inlet pipe, it passes through the internal mediating cavity and the coalescing layer of the coalescing filter element in sequence, thus completing the dual functions of suspended solids filtration and oil droplet coalescence.

[0006] Furthermore, the coalescing filter element is tubular, arranged vertically or inclinedly inside the housing, with its upper part connected to the water inlet pipe and its lower part connected to the water outlet pipe.

[0007] Furthermore, the tank is also equipped with a backwash inlet, which is connected to a backwashing system for rinsing the packing material. All valves in the tank except for the backwash inlet and backwash outlet are closed. The backwash inlet enters the filter element from the bottom of the coalescing filter element in the reverse direction, and the backwash outlet is connected to a bypass via the inlet pipe and returned to the regulating tank or the pretreatment unit.

[0008] Furthermore, a drain outlet is provided at the bottom of the tank.

[0009] Furthermore, an exhaust valve is provided on the top of the tank.

[0010] Furthermore, a manhole is provided on the top of the tank.

[0011] Furthermore, the coalescing filter element consists of a coalescing material layer, a support mesh, and a packing cavity from the outside to the inside, and also includes an upper connector and a lower connector to realize the installation and disassembly of the coalescing filter element.

[0012] Furthermore, the filter media is located in the filter media cavity, and the filter media is a hydrophilic oil-removing modified quartz sand filter material with a particle size of 0.2-0.5 mm. It has advantages such as excellent storage stability of modified solutions, excellent film-forming performance, low preparation cost, and wide adaptability.

[0013] Furthermore, the hydrophilic degreasing modified quartz sand filter media is obtained by impregnating or spraying quartz sand with a silicone-acrylic emulsion type hydrophilic modification solution and then curing it.

[0014] Furthermore, the preparation method of the silicone-acrylic emulsion type hydrophilic modified solution includes the following steps: Butyl acrylate, methyl methacrylate, acrylic acid, and γ-methacryloyloxypropyltrimethoxysilane were added to an emulsion containing sodium dodecyl sulfate and octylphenol polyoxyethylene ether, and emulsified to obtain a pre-emulsion. A portion of the pre-emulsion and a portion of the initiator were added to deionized water and heated to reflux. Then, another portion of the pre-emulsion and another portion of the initiator were added dropwise to the reflux system and kept at a constant temperature for reaction. After the reaction was completed, the pH of the system was adjusted, and then levulinic acid and a bactericide were added. The mixture was stirred and filtered to obtain a silicone-acrylic emulsion-type hydrophilic modified solution.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention places the filter packing inside the coalescing filter element, breaking it down into smaller parts, avoiding large-scale packing layer caking and extending the cleaning cycle.

[0016] (2) The oil removal equipment of the present invention integrates oil removal and filtration functions, has a compact structure, occupies little space, and is suitable for occasions with limited space.

[0017] (3) The coalescing filter element in the device of the present invention can be disassembled and replaced or cleaned separately, which is convenient to maintain and has low operating cost.

[0018] (4) The oil removal equipment of the present invention is suitable for oily wastewater treatment systems with large fluctuations in water quality, and the effluent water quality is stable and reliable. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the combined filtration and oil removal equipment of the present invention, wherein 1 is the tank body, 2 is the water inlet pipe (backwash outlet), 3 is the water outlet pipe, 4 is the coalescing filter element, 5 is the filter packing, 6 is the oil collection chamber, 7 is the backwash inlet, 8 is the drain outlet, 9 is the exhaust valve, and 10 is the manhole.

[0020] Figure 2 This is a schematic diagram of the internal structure of the coalescing filter element of the present invention, wherein 1 is the coalescing material layer, 2 is the support mesh, 3 is the packing cavity, 4 is the upper connector, and 5 is the lower connector. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] A schematic diagram of the combined filtration and oil removal equipment of the present invention is shown below. Figure 1 As shown, this equipment includes a tank (1), an inlet pipe (backwash outlet) (2), an outlet pipe (3), and an oil collection chamber (6). Multiple coalescing filter elements (4) are installed inside the tank. In a specific embodiment, there are 5 coalescing filter elements, each filled with filter media (5). The backwash inlet (7) is connected to the backwashing system. A drain outlet (8) is located at the bottom of the tank, and an exhaust valve (9) and a manhole (10) are located at the top. Wastewater enters the tank tangentially from the inlet pipe. Suspended solids are removed by the internal filter media. After passing through the outer wall of the coalescing filter element where oil droplets coalesce, the oil droplets float to the oil collection chamber, and clean water is discharged from the outlet pipe.

[0025] A schematic diagram of the internal structure of the coalescing filter element is shown below. Figure 2 As shown, the coalescing filter element consists of a coalescing material layer (1), a support mesh (2), and a packing cavity (3) from the outside to the inside. It also includes an upper connector (4) and a lower connector (5) to enable sealed installation and disassembly of the filter element. The packing cavity is filled with superhydrophilic oil-removing modified quartz sand filter media, which has both hydrophilicity and oil droplet coalescing functions. The hydrophilic oil-removing modified quartz sand filter media is obtained by impregnating or spraying quartz sand with a silicone-acrylic emulsion-type hydrophilic modification solution and then curing it.

[0026] The preparation method of the superhydrophilic oil-removing modified quartz sand filter media in the specific embodiment is as follows: Add 280g deionized water, 3.5g SDS, and 3.5g OP-10 to a beaker, stir to dissolve, and then start a high-speed disperser (1000rpm). Add 120g butyl acrylate, 80g methyl methacrylate, 12g acrylic acid, and 40g KH-570 sequentially, and continue emulsifying for 15 minutes to obtain a stable "monomer pre-emulsion," which is then set aside. Add 280g deionized water to a 1L glass reactor, turn on the reflux condenser, and heat to 80℃. Add 20% of the pre-emulsion + 0.4g ammonium persulfate (APS), and maintain the temperature for 20 minutes. Add the remaining pre-emulsion and 0.8g... APS (dissolved in 20g deionized water) was added dropwise to the reactor simultaneously through a constant-pressure dropping funnel, controlling the dropping rate to ensure completion within 2.5 hours. After addition, the mixture was kept at 80℃ for 1 hour, then allowed to cool naturally to 45℃. The pH of the system was adjusted to 5.5 with 10% ammonia. 2.0g of levulinic acid and 1.0g of isothiazolinone bactericide were added, and stirring continued for 15 minutes. The mixture was then filtered through a 200-mesh filter to obtain a silicone-acrylic emulsion-type superhydrophilic modifier. The emulsion appeared as a semi-permeable emulsion with a solid content of 30%. The tested viscosity was 113 mPa·s (25℃, #3 rotor 60 rpm), the particle size was 80-120 nm, and the shelf life at 25℃ was 24 months. The purity was selected... High-purity quartz sand with a purity of ≥99.9% was rinsed with deionized water to remove surface impurities, dried at 80℃ for 30 min, and then treated with 400W plasma for 18 min to construct hydroxyl (-OH) active sites on the surface of the quartz sand, increasing the activation degree to over 85%. The prepared silicone-acrylic emulsion type superhydrophilic modifier was diluted with tap water at a ratio of 1:5 and stirred gently for 5 min until homogeneous (the viscosity after dilution decreased to 12 mPa·s, resembling milk). No further curing was required. The pretreated quartz sand was immersed in the diluted modifier and soaked at room temperature for 5 min. After being removed, it was drained for 10 min. The drained quartz sand was placed in an 80℃ oven to dry for 30 min, or left at room temperature for 2 h to surface dry. After 24 h, it was completely cured to obtain oil-free superhydrophilic modified quartz sand. The modified quartz sand is covered with a transparent soft film with an average thickness of 0.8 μm. Testing showed a water contact angle of 9.4°, exhibiting significant superhydrophilic and superoleophobic properties. Under conditions of an influent oil concentration of 500 mg / L and a filtration rate of 10 m / h, its oil removal rate was ≥90%. Under conditions of an influent TOC concentration of 2000 mg / L and a filtration height of 1.2 m, its TOC removal rate was ≥75%. Membrane weight loss after 30 minutes of backwashing at 0.4 MPa was <1%. Under continuous operation, the backwash cycle was >30 days with no risk of caking. Under normal industrial operating conditions, its service life is 3-5 years.

[0027] Example 1 In an oily wastewater treatment system at a thermal power plant, the petroleum content was approximately 2000 mg / L, and the suspended solids content was approximately 200 mg / L. The oil removal equipment of this invention was used as the final filtration unit, replacing the original multi-media quartz sand filter and coalescing oil separator. Operational results showed that after three months of continuous operation, no packing caking occurred, the backwash cycle was extended to once every seven days, and the effluent oil content remained consistently below 8 mg / L, with suspended solids below 2 mg / L, meeting discharge requirements.

[0028] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A combined filtration and oil removal device for treating oily wastewater, comprising a tank, an inlet pipe, an outlet pipe, and an oil collection chamber disposed on the tank, characterized in that: The tank is equipped with multiple detachable coalescing filter elements, each filled with filter media. The coalescing filter element includes an outer coalescing layer and an inner median cavity. After the wastewater enters the shell through the inlet pipe, it passes through the inner median and the coalescing layer of the coalescing filter element in sequence, thus completing the dual functions of suspended solids filtration and oil droplet coalescence.

2. The combined filtration and oil removal equipment for treating oily wastewater according to claim 1, characterized in that, The coalescing filter element is tubular and is arranged vertically or inclined inside the housing, with the upper part connected to the water inlet pipe and the lower part connected to the water outlet pipe.

3. The combined filtration and oil removal equipment for treating oily wastewater according to claim 2, characterized in that, The tank is also equipped with a backwash inlet, which is connected to the backwashing system for rinsing the packing material. All valves in the tank except for the backwash inlet and backwash outlet are closed. The backwash inlet enters the filter element from the bottom of the coalescing filter element in the reverse direction, and the backwash outlet is returned to the regulating tank or the pretreatment unit via the inlet pipe.

4. The combined filtration and oil removal equipment for treating oily wastewater according to claim 1, characterized in that, A drain outlet is provided at the bottom of the tank.

5. A combined filtration and oil removal device for treating oily wastewater according to claim 1, characterized in that, An exhaust valve is installed on the top of the tank.

6. A combined filtration and oil removal device for treating oily wastewater according to claim 1, characterized in that, A manhole is provided on the top of the tank.

7. A combined filtration and oil removal device for treating oily wastewater according to claim 1, characterized in that, The coalescing filter element consists of a coalescing material layer, a support mesh, and a packing cavity from the outside to the inside. It also includes an upper connector and a lower connector to enable the installation and removal of the coalescing filter element.

8. A combined filtration and oil removal device for treating oily wastewater according to claim 1, characterized in that, The filter media is located in the filter media cavity, and the filter media is a hydrophilic oil-removing modified quartz sand filter media.

9. A combined filtration and oil removal device for treating oily wastewater according to claim 8, characterized in that, The hydrophilic degreasing modified quartz sand filter media is obtained by impregnating or spraying quartz sand with a silicone-acrylic emulsion type hydrophilic modification solution and then curing it.

10. A combined filtration and oil removal device for treating oily wastewater according to claim 9, characterized in that, The preparation method of the silicone-acrylic emulsion type hydrophilic modified solution includes the following steps: Butyl acrylate, methyl methacrylate, acrylic acid, and γ-methacryloyloxypropyltrimethoxysilane were added to an emulsion containing sodium dodecyl sulfate and octylphenol polyoxyethylene ether, and emulsified to obtain a pre-emulsion. A portion of the pre-emulsion and a portion of the initiator were added to deionized water and heated to reflux. Then, another portion of the pre-emulsion and another portion of the initiator were added dropwise to the reflux system and kept at a constant temperature for reaction. After the reaction was completed, the pH of the system was adjusted, and then levulinic acid and a bactericide were added. The mixture was stirred and filtered to obtain a silicone-acrylic emulsion-type hydrophilic modified solution.

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