Ultrasonic separation and recovery device and method for kitchen wastewater grease

Abstract

The device comprises a raw water temporary storage tank, a water outlet of the raw water temporary storage tank is connected with a water inlet of a high-speed separator, a water outlet of the high-speed separator is connected with a water inlet of a settling tank, and a water outlet of the settling tank is connected with a water outlet pool. An overflow port of the settling tank is connected with a water inlet of the ultrasonic separator, a water outlet of the ultrasonic separator is connected with the water outlet pool, an oil outlet of the ultrasonic separator is connected with an oil inlet of the grease storage tank, and a circulating water outlet of the ultrasonic separator is connected with a water inlet of the circulating pump; a water outlet of the circulating pump is connected with a circulating water inlet of the ultrasonic separator, a cleaning pump is arranged on a pipeline of a cleaning water inlet of the high-speed separator, a slag outlet of the high-speed separator is connected with a slag inlet of the slag outlet box, and a slag outlet of the slag outlet box is connected with the sludge tank. According to the invention, suspended solids in kitchen wastewater can be effectively removed, and efficient separation and recovery of grease are realized.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to an ultrasonic separation and recovery device and method for kitchen wastewater grease. Background Technology

[0002] Currently, kitchen wastewater from food waste projects is directly transported to the wastewater treatment plant without undergoing grease separation. It is treated using a process of anaerobic fermentation + A / O denitrification + membrane filtration. The large amount of suspended solids and residual grease in the kitchen wastewater increases the difficulty of downstream treatment, especially impacting the anaerobic and membrane systems, resulting in increased anaerobic load and frequent membrane clogging, which greatly increases treatment costs and failure rate.

[0003] Patent CN102225794A discloses a combined oil-water separation device and method for kitchen waste wastewater. It consists of inlet and outlet pipes, a filter screen, an grease aggregation layer, a spindle coalescing and transport layer, an oil-water separation membrane layer, a pulley oil conveying device, an overflow pipe, and a wastewater tank. It collects grease from the wastewater using a special grease coalescing material and a spindle fiber coalescing method. However, this patent uses a simple coalescing material, which is only suitable for separating large-particle-size discrete oils and dispersed oils. It cannot demulsify and separate emulsified oil-water mixtures. Furthermore, its simple filtration method cannot remove the large amount of suspended solids in kitchen wastewater, which significantly impacts the downstream coalescing unit, resulting in low oil-water separation efficiency.

[0004] Patent CN209052429U discloses a wastewater grease separation device for food waste treatment. It mainly consists of two areas: natural sedimentation and flotation separation, separated by a partition. The first separation area is for natural sedimentation, and the second is for flotation separation. This two-stage separation method achieves grease separation and recovery. While this patent is effective for separating conventional free grease, it is not well-suited for separating grease from food wastewater. This is because grease and suspended solids in food wastewater have strong adhesion, making sedimentation impossible. In flotation mode, suspended solids and grease are carried to the surface by air bubbles, making separate grease separation impossible.

[0005] Patent CN212102393U discloses an oil-water separation device, which includes an interconnected mixing chamber, a sedimentation chamber, an air flotation chamber, and an ultrasonic separation chamber. It achieves oil-water separation through three different methods. This patent has a good effect on ordinary oily wastewater, but kitchen wastewater has a complex composition and high suspended solids content. Sedimentation and air flotation methods cannot effectively remove grease and suspended solids. After entering the ultrasonic treatment unit, due to the high concentration of suspended solids, the energy of the ultrasonic waves is insufficient to achieve grease separation.

[0006] If suspended solids and grease in kitchen wastewater can be separated and recycled, it will not only reduce the difficulty and cost of downstream wastewater treatment, but also generate economic benefits and increase the income of kitchen waste projects, achieving a win-win effect. Summary of the Invention

[0007] Technical problem solved: In view of the above-mentioned technical problems, the present invention provides an ultrasonic separation and recovery device and method for kitchen wastewater, which can effectively solve the problems of existing methods not performing oil recovery treatment, high suspended solids content in kitchen wastewater and difficulty in oil-water separation.

[0008] Technical Solution: In a first aspect, the present invention provides an ultrasonic separation and recovery device for kitchen wastewater grease, comprising a raw water storage tank, the outlet of which is connected to the inlet of a high-speed separator, the outlet of which is connected to the inlet of a settling tank, the outlet of which is connected to an effluent pool, the overflow outlet of which is connected to the inlet of an ultrasonic separator, the outlet of which is connected to an effluent pool, the oil outlet of which is connected to the inlet of an grease storage tank, the circulation outlet of which is connected to the inlet of a circulation pump, the outlet of which is connected to the circulation inlet of the ultrasonic separator, a cleaning pump is installed on the pipe of the cleaning inlet of the high-speed separator, the slag outlet of which is connected to the slag inlet of a slag discharge box, and the slag outlet of which is connected to a sludge pool.

[0009] Preferably, a raw material pump is installed on the pipe at the inlet of the raw water storage tank.

[0010] Preferably, a valve is provided on the pipe connecting the outlet of the raw water storage tank and the inlet of the high-speed separator.

[0011] Preferably, the inlet of the settling tank is located in the lower middle part, the overflow outlet is higher than the inlet, and the drain outlet is lower than the inlet.

[0012] Preferably, the top of the ultrasonic separator is provided with an oil tank, the oil outlet of the oil tank is connected to the oil inlet of the grease storage tank through a pipe, and the oil tank is provided with a glass sight glass and an oil-water interface gauge; the side wall of the ultrasonic separator is provided with an ultrasonic transducer.

[0013] Furthermore, the ultrasonic transducer is a wall-mounted type, the ultrasonic frequency is 20~40kHz, the installation position is in the lower middle part of the ultrasonic separator, and the installation spacing of the ultrasonic transducer is 100mm.

[0014] Preferably, the inlet of the ultrasonic separator is located in the upper middle part, the outlet is located at the bottom, and the distance between the inlet and the outlet is greater than half the height of the ultrasonic separator.

[0015] Preferably, the capacity of the ultrasonic separator needs to ensure that the residence time of the material inside is greater than 10 minutes, and the diameter of the ultrasonic separator is not greater than 1 m.

[0016] Secondly, the present invention provides a method for ultrasonic separation and recovery of grease from kitchen wastewater based on the device described in the first aspect. The kitchen wastewater is pumped to a high-speed separator for solid-liquid separation. The effluent from the high-speed separator, which removes more than 90% of the suspended solids, flows into a settling tank. Grease and light suspended solids float to the top of the settling tank due to density difference. After reaching the overflow level, the oily wastewater overflows into an ultrasonic separator. Under the action of ultrasound, grease and suspended solids are separated and float to the oil tank of the ultrasonic separator and accumulate. After the grease reaches the overflow level, it flows into the grease storage tank, thereby realizing the separation and recovery of grease. The slag phase of the high-speed separator is discharged to the slag box for temporary storage and then pumped to the sludge tank by a screw pump. The low-oil-content wastewater at the bottom of the settling tank and the wastewater after oil removal at the bottom of the ultrasonic separator are both pumped to the effluent pool for centralized treatment.

[0017] Preferably, the rinsing process is initiated when the suspended solids concentration in the effluent from the high-speed separator reaches 10,000 mg / L or above. The rinsing process is powered by a rinsing pump, and the rinsing water is recycled water or tap water. The rinsing time is 20 minutes.

[0018] Beneficial Effects: Addressing the challenges of complex composition, high suspended solids content, and high adhesion of grease and suspended solids in kitchen wastewater, conventional sedimentation, cyclone, and flotation technologies struggle to achieve grease separation and recovery. Combining multiple technologies can lead to lengthy processes, high investment and operating costs, and secondary pollution, while also resulting in poor grease separation and recovery. This invention employs a novel process and equipment that enables highly efficient separation and recovery of grease and suspended solids from kitchen wastewater. Specific advantages are as follows: 1) Good oil separation and recovery effect: Although existing technologies such as sedimentation, cyclone and flotation can separate a small amount of oil, the separation effect is low. The separated oil and suspended solids are not completely separated, and the oil is difficult to recover or the recovery rate is low. 2) Simple process flow: Due to the characteristics of kitchen wastewater, grease separation and recovery are extremely difficult. Conventional methods require a long process and a large amount of equipment, such as sedimentation tanks, flotation tanks, multi-stage filters, centrifuges, etc. This patent can achieve the purpose of grease separation and recovery with only a small amount of equipment, and the process flow is simple. 3) Good operational stability: The invention has a small number of devices, among which the high-speed separator is a mature centrifugal device, and the settling tank and ultrasonic separator are static devices, which have the advantages of low failure rate and stable operation. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the structure of an ultrasonic separation and recovery device for kitchen wastewater grease according to the present invention; Figure 2 This is a schematic diagram of the ultrasonic separator of the present invention; The numbers in the diagram are as follows: 1. Raw material pump, 2. Raw water storage tank, 3. Valve, 4. High-speed separator, 5. Settling tank, 6. Ultrasonic separator, 61. Inlet, 62. Outlet, 63. Oil outlet, 64. Circulating inlet, 65. Circulating outlet, 66. Ultrasonic transducer, 67. Oil tank, 7. Circulating pump, 8. Grease storage tank, 9. Water discharge pump, 10. Flushing pump, 11. Slag discharge box, 12. Screw pump, 13. Sludge tank, 14. Water discharge tank. Detailed Implementation

[0020] The present invention will be described in detail below with reference to specific embodiments: Example 1

[0021] like Figure 1 and Figure 2 As shown: A kitchen wastewater grease ultrasonic separation and recovery device includes a raw water storage tank 2. The outlet of the raw water storage tank 2 is connected to the inlet of a high-speed separator 4. The high-speed separator 4 can intercept more than 90% of the suspended solids in the influent and discharges sludge intermittently at a frequency of once every 3 minutes, with the sludge discharge amount being about 10% of the total influent volume. The outlet of the high-speed separator 4 is connected to the inlet of a settling tank 5. The outlet of the settling tank 5 is connected to an effluent pool 14. The overflow port of the settling tank 5 is connected to the inlet 61 of an ultrasonic separator 6. The outlet 62 of the ultrasonic separator 6 is connected to the effluent pool 14. Oil port 63 is connected to the oil inlet of grease storage tank 8. The circulating water outlet 64 of ultrasonic separator 6 is connected to the water inlet of circulating pump 7. The water outlet of circulating pump 7 is connected to the circulating water inlet 65 of ultrasonic separator 6. Circulating pump 7 draws water from the bottom of ultrasonic separator 6 to the top, which plays a stirring role inside ultrasonic separator 6. In addition, it can also be switched to clean water mode by valve to clean ultrasonic separator 6. A cleaning pump 10 is installed on the pipe of the cleaning water inlet of high-speed separator 4. The slag outlet of high-speed separator 4 is connected to the slag inlet of slag box 11. The slag outlet of slag box 11 is connected to sludge tank 13.

[0022] A raw material pump 1 is installed on the pipe at the inlet of the aforementioned raw water storage tank 2.

[0023] A valve 3 is installed on the pipe connecting the outlet of the above-mentioned raw water storage tank 2 to the inlet of the high-speed separator 4. When the high-speed separator 4 is being flushed or malfunctioning, the kitchen wastewater can be temporarily stored by closing the valve 3.

[0024] The inlet of the settling tank 5 is located in the middle and lower part, the overflow outlet is higher than the inlet, and the drain outlet is lower than the inlet, so as to provide sufficient settling time to ensure that the grease floats to the liquid surface.

[0025] The ultrasonic separator 6 is equipped with an oil reservoir 67 at its top. The oil outlet 63 of the oil reservoir 67 is connected to the oil inlet of the grease storage tank 8 via a pipe. The oil reservoir 67 is equipped with a glass sight glass and an oil-water level gauge to monitor the oil level and achieve real-time oil discharge. The side wall of the ultrasonic separator 6 is equipped with ultrasonic transducers 66. The ultrasonic transducers 66 are wall-mounted, with an ultrasonic frequency of 20~40kHz. They are installed in the lower middle part of the ultrasonic separator 6, and the installation spacing of the ultrasonic transducers 66 is 100mm.

[0026] The inlet 61 of the ultrasonic separator 6 is located in the upper middle part, and the outlet 62 is located at the bottom. The distance between the inlet 61 and the outlet 62 is greater than half the height of the ultrasonic separator 61 to prevent short-flow phenomenon.

[0027] The capacity of the ultrasonic separator 6 mentioned above needs to ensure that the residence time of the material inside is greater than 10 minutes in order to ensure sufficient ultrasonic action time and separation effect. At the same time, the length-to-diameter ratio of the ultrasonic separator 6 needs to take into account the ultrasonic action distance, and the diameter should preferably not exceed 1m. Example 2

[0028] The method for ultrasonic separation and recovery of grease from kitchen wastewater using the apparatus of Example 1 involves the following steps: Kitchen wastewater is pumped by raw material pump 1 to high-speed separator 4 for solid-liquid separation. The effluent from high-speed separator 4, which removes more than 90% of suspended solids, flows into settling tank 5. Grease and light suspended solids float to the top of settling tank 5 due to density difference. Once the overflow level is reached, the oily wastewater overflows into ultrasonic separator 6. Under ultrasonic action, grease and suspended solids are separated and float to the oil reservoir 67 of ultrasonic separator 6. Once the grease reaches the overflow level, it flows into grease storage tank 8, thus achieving grease separation and recovery. The slag phase from high-speed separator 4 is temporarily stored in slag box 11 and then pumped to sludge tank 13 by screw pump 12. The low-oil-content wastewater at the bottom of settling tank 5 and the oil-removed wastewater at the bottom of ultrasonic separator 6 are both pumped to effluent pool 14 for centralized treatment via effluent pump 9.

[0029] When the suspended solids concentration in the effluent from the high-speed separator 4 reaches 10,000 mg / L or above, the rinsing process is initiated. The rinsing process is powered by the rinsing pump 10, and the rinsing water is either recycled water or tap water. The rinsing time is 20 minutes.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ultrasonic separation and recovery device for kitchen wastewater grease, characterized in that: The system includes a raw water storage tank (2), the outlet of which is connected to the inlet of a high-speed separator (4), the outlet of which is connected to the inlet of a settling tank (5), the outlet of which is connected to the outlet of a settling tank (5), the outlet of which is connected to an outlet pool (14), the overflow outlet of which is connected to the inlet (61) of an ultrasonic separator (6), the outlet (62) of which is connected to the outlet pool (14), and the oil outlet of which is connected to the outlet of the ultrasonic separator (6). 63) Connected to the oil inlet of the grease storage tank (8), the circulation outlet (64) of the ultrasonic separator (6) is connected to the inlet of the circulation pump (7), the outlet of the circulation pump (7) is connected to the circulation inlet (65) of the ultrasonic separator (6), a cleaning pump (10) is provided on the pipe of the cleaning inlet of the high-speed separator (4), the slag outlet of the high-speed separator (4) is connected to the slag inlet of the slag box (11), and the slag outlet of the slag box (11) is connected to the sludge tank (13).

2. The ultrasonic separation and recovery device for kitchen wastewater grease according to claim 1, characterized in that: The raw water storage tank (2) is equipped with a raw material pump (1) on the pipe at the inlet.

3. The ultrasonic separation and recovery device for kitchen wastewater grease according to claim 1, characterized in that: A valve (3) is provided on the pipe connecting the outlet of the raw water storage tank (2) and the inlet of the high-speed separator (4).

4. The ultrasonic separation and recovery device for kitchen wastewater grease according to claim 1, characterized in that: The inlet of the settling tank (5) is located in the middle and lower part, the overflow outlet is higher than the inlet, and the drain outlet is lower than the inlet.

5. The ultrasonic separation and recovery device for kitchen wastewater grease according to claim 1, characterized in that: The top of the ultrasonic separator (6) is provided with an oil tank (67), the oil outlet (63) of the oil tank (67) is connected to the oil inlet of the grease storage tank (8) through a pipe, and the oil tank (67) is provided with a glass sight glass and an oil-water interface gauge; the side wall of the ultrasonic separator (6) is provided with an ultrasonic transducer (66).

6. The ultrasonic separation and recovery device for kitchen wastewater grease according to claim 5, characterized in that: The ultrasonic transducer (66) is a wall-mounted type, with an ultrasonic frequency of 20~40kHz. It is installed in the lower middle part of the ultrasonic separator (6), and the installation spacing of the ultrasonic transducer (66) is 100mm.

7. The ultrasonic separation and recovery device for kitchen wastewater grease according to claim 1, characterized in that: The inlet (61) of the ultrasonic separator (6) is located in the upper middle part, and the outlet (62) is located at the bottom. The distance between the inlet (61) and the outlet (62) is greater than half the height of the ultrasonic separator (61).

8. The ultrasonic separation and recovery device for kitchen wastewater grease according to claim 1, characterized in that: The capacity of the ultrasonic separator (6) needs to meet the requirement that the residence time of the material inside it is greater than 10 minutes, and the diameter of the ultrasonic separator (6) is not greater than 1 m.

9. A method for ultrasonic separation and recovery of grease from kitchen wastewater based on the apparatus according to any one of claims 1-8, characterized in that: Kitchen wastewater is pumped by raw material pump (1) to high-speed separator (4) for solid-liquid separation. The high-speed separator (4) removes more than 90% of the suspended solids. The effluent from the high-speed separator (4) flows into settling tank (5). Oil and light suspended solids float to the top of settling tank (5) under the action of density difference. After reaching the overflow level, the oily wastewater overflows to ultrasonic separator (6). Under the action of ultrasound, oil and suspended solids are separated and float to the oil bag (67) of ultrasonic separator (6) and accumulate. After the oil reaches the overflow level, it flows to oil storage tank (8), thereby realizing the separation and recovery of oil. The slag phase of high-speed separator (4) is discharged to slag box (11) for temporary storage, and then pumped to sludge tank (13) by screw pump (12). The low oil content wastewater at the bottom of settling tank (5) and the wastewater after oil removal at the bottom of ultrasonic separator (6) are both pumped to effluent pool (14) for centralized treatment by effluent pump (9).

10. The method according to claim 9, characterized in that, When the concentration of suspended solids in the water discharged from the high-speed separator (4) reaches 10000 mg / L or above, the rinsing process is started. The rinsing process is powered by the rinsing pump (10), and the rinsing water is recycled water or tap water. The rinsing time is 20 minutes.

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