Kitchen garbage oil high-efficiency separation and deodorization integrated treatment process

Abstract

The application discloses a kind of kitchen garbage oil high-efficiency separation and deodorization integrated processing technology, belong to solid waste treatment technical field.Preprocessing and crushing conditioning, add the composite conditioning agent consisting of citric acid, sodium chloride and lipase;Coupling separation of cyclone-coalescence, through cyclone generator and oil-wet hydrophobic coalescence separation plate group realizes oil high-efficiency separation;Synergistic oxidative deodorization, water phase uses ozone-micro-nano bubble oxidation, oil phase uses ion hydrolysis-catalytic oxidation treatment;Deep purification and discharge.The application is through crushing conditioning synergistic demulsification, cyclone-coalescence coupling enhanced separation, the technology integration of quality cooperation oxidative deodorization, effectively solve the problem of low oil separation efficiency, deodorization processing lag, unit operation fragmentation in prior art.After the process of the application, oil separation rate can reach more than 98.5%, hydrogen sulfide removal rate can reach more than 99%, operating cost is reduced by more than 30% compared with prior art.

Description

Technical Field

[0001] This invention relates to the field of solid waste treatment and environmental protection technology, specifically to an integrated process for efficient separation and deodorization of grease from kitchen waste. Background Technology

[0002] With the rapid development of my country's catering industry and the improvement of residents' living standards, the amount of kitchen waste generated has been increasing year by year. According to statistics, the amount of kitchen waste generated in major Chinese cities has exceeded 200,000 tons per day, of which the oil content is as high as 10%-30%. If not handled properly, it will not only waste resources, but also cause serious environmental pollution problems.

[0003] Regarding the separation and deodorization of grease from kitchen waste, utility model patent CN213671052U discloses a kitchen waste treatment device with a deodorization mechanism. This device achieves solid-liquid separation, oil-liquid separation, and deodorization of kitchen waste by incorporating a crushing mechanism, a solid-liquid separation mechanism, an oil-water separation mechanism, and a deodorization plate. This technology uses a grid plate for solid-liquid separation, utilizes a front baffle, a rear baffle, and a separation plate within the separation chamber for oil-water separation, and simultaneously uses an activated carbon deodorization plate to adsorb odorous gases. Another example is patent application CN105296165A, which discloses a comprehensive pretreatment method for kitchen waste and gutter oil, employing a two-stage centrifugal separation method for grease purification to improve separation accuracy. Yet another example is patent application CN113716984A, which discloses a kitchen waste fermentation treatment system that uses ice water to cool and solidify grease before scooping it out for degreasing. In addition, existing technologies also include equipment solutions using ozone generators and ion hydrolysis generators for deodorization.

[0004] The existing technology still has the following shortcomings: 1. Although existing equipment has integrated unit operations such as solid-liquid separation and oil-water separation, there is a lack of coordinated optimization design between the units. In particular, the grease separation unit and the deodorization unit operate independently, making it difficult to further improve the processing efficiency. When grease separation is incomplete, residual grease will undergo anaerobic reactions in subsequent treatment stages, producing a large amount of malodorous gases and increasing the burden on the deodorization system. 2. Existing gravity separation or simple centrifugal separation methods are insufficient for efficiently separating emulsified oils. The separated oils have high water content and many impurities, resulting in low value for subsequent resource utilization. Traditional bar screens or filters are ineffective at trapping fine oil droplets, leading to large amounts of oil being discharged with wastewater, which not only wastes resources but also increases the load on wastewater treatment. 3. Most existing technologies use end-of-pipe activated carbon adsorption for odor removal, which is prone to leakage during collection and transportation of odorous gases; activated carbon needs to be replaced after saturation, and discarded activated carbon is hazardous waste, resulting in high treatment costs. Some technologies use ion hydrolysis or ozone oxidation, but these do not synergize with the oil separation process, leading to high energy consumption. 4. Oil and grease accumulate in the oil-water separator over a long period, and under anaerobic conditions, they easily deteriorate and ferment, becoming a new source of foul odor. Although existing technologies include deodorization devices, they often fail to suppress odor generation at its source.

[0005] In conclusion, developing an integrated treatment process that can achieve efficient grease separation and deodorization, along with optimized coupling of each unit, is of great significance for improving the efficiency of kitchen waste treatment, reducing operating costs, and realizing resource utilization. Summary of the Invention

[0006] This invention aims to solve the technical problems of low grease separation efficiency, delayed deodorization, and fragmented unit operations in the existing kitchen waste treatment technology, and provides an integrated process for efficient grease separation and deodorization of kitchen waste.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an integrated process for efficient separation and deodorization of kitchen waste grease, comprising the following steps: Step 1, Pretreatment and Crushing / Tempering: The collected kitchen waste is transported to the crushing / tempering unit. During crushing, a compound tempering agent is added to the material. The material temperature is controlled at 40-60℃ and the pH value is 5.5-6.5. The compound tempering agent is composed of citric acid, sodium chloride and lipase in a mass ratio of 2-5:1-3:0.5-1. Step 2, Cyclone-Coalescence Coupling Separation: The material processed in Step 1 is fed into the cyclone-coalescence coupling separation unit, which includes a cyclone generator and a coalescence separation plate assembly. Under the action of cyclone, the material forms a high-speed rotating flow field. Oil droplets migrate towards the inner wall under the action of centrifugal force, and then flow through the coalescence separation plate assembly. The surface of the coalescence separation plate assembly is provided with an oleophilic and hydrophobic coating. Small oil droplets coalesce and grow on the surface of the plate assembly and float to form an oil layer. Step 3, Synergistic Oxidation Deodorization Treatment: The aqueous phase and oil phase separated in Step 2 are deodorized separately. The aqueous phase is mixed with ozone-micro-nano bubbles through a gas-liquid mixing device. The ozone dosage is 30-80 mg / L and the micro-nano bubble particle size is 200-800 nm. The oil phase is treated by an ion hydrolysis-catalytic oxidation combined device. The treatment temperature is controlled at 50-70℃ and the hydraulic retention time is 15-30 min. Step 4, Deep Purification and Discharge: The aqueous phase after Step 3 is filtered through a multi-media system and then discharged or reused. The treated oil phase is refined and collected as a feedstock for biodiesel.

[0008] Furthermore, in the swirling-coalescence coupling separation unit, the swirling velocity gradient generated by the swirling generator is 200-500 s. -1 The coalescing separation plate assembly is composed of 3-8 layers of corrugated plates with a plate spacing of 5-15mm and a micron-level groove structure on the plate surface.

[0009] Furthermore, the oleophilic and hydrophobic coating is a modified silica-polytetrafluoroethylene composite coating with a thickness of 20-100 μm, a water contact angle ≥140°, and an oil contact angle ≤10°.

[0010] Furthermore, in the ozone-micro / nano bubble mixing treatment, the gas-liquid volume ratio is 1:5-1:15, the micro / nano bubble generating device adopts a pressure dissolved gas-shear composite generation method, and the bubble rising speed is 0.1-0.5 mm / s.

[0011] Furthermore, the ion hydrolysis-catalytic oxidation combined device is equipped with a titanium-based supported catalyst, the active component of which is a composite of MnO2, CeO2 and Pt in a mass ratio of 5-10:2-5:0.5-1, and the catalyst packing density is 0.3-0.6 g / cm³.

[0012] Furthermore, the multi-media filtration uses a three-layer filter media of quartz sand, activated carbon, and zeolite, with a filter media layer height ratio of 2:1:1 and a filtration speed of 8-12 m / h.

[0013] Furthermore, the dosage of the composite conditioning agent is 0.5-2.0% of the mass of kitchen waste.

[0014] Furthermore, in step one, the crushing particle size of the crushing and conditioning unit is 5-10 mm, and the conditioning time is 10-20 min.

[0015] Furthermore, the hydraulic residence time of the swirl-coalescence coupling separation unit in step two is 4-10 min.

[0016] Furthermore, the water phase after multi-media filtration in step four meets the water quality standards for industrial water reuse in urban wastewater recycling and is reused for conditioning and replenishment or equipment cleaning in step one.

[0017] This invention introduces a composite conditioning agent during the crushing stage. Citric acid adjusts the pH value, disrupting the stability of the oil-water interface film; sodium chloride alters the ionic strength of the aqueous phase, promoting oil droplet aggregation; and lipase partially hydrolyzes the oil, reducing its interfacial tension. The synergistic effect of these three agents demulsifies the emulsified oil, creating conditions for subsequent efficient separation. Compared to existing technologies that rely solely on physical crushing, this invention significantly increases the proportion of free oil through the synergy of chemical conditioning and physical crushing.

[0018] Traditional gravity separation relies on the density difference between oil and water, and its efficiency is limited by residence time. This invention couples cyclone separation with coalescence separation: the high-shear flow field generated by the cyclone generator gives the dispersed phase oil droplets centrifugal acceleration to migrate towards the wall, significantly shortening the separation time; subsequently, when flowing through the coalescence separation plate assembly with an oleophilic and hydrophobic coating, the oil droplets spread, coalesce, and grow on the plate surface, forming a continuous oil film that floats to the surface. This coupling mechanism breaks through the efficiency bottleneck of single separation methods, achieving highly efficient separation with short residence times.

[0019] This invention employs a differentiated deodorization strategy to address the characteristics of different media. Residual odorous substances in the aqueous phase, such as hydrogen sulfide, ammonia, and volatile fatty acids, are removed through ozone-micro / nanobubble oxidation. Micro / nanobubbles, with their large specific surface area, slow rise velocity, and high gas-liquid mass transfer efficiency, significantly improve ozone utilization. Odorous substances in the oil phase, mainly small-molecule aldehydes, ketones, and amines, are treated using an ion hydrolysis-catalytic oxidation combined device, achieving efficient degradation under the action of a catalyst. This phased treatment method avoids the problems of low efficiency and high energy consumption associated with single-method treatment.

[0020] This invention reduces the content of organic matter suitable for anaerobic fermentation at the source through efficient oil separation, thereby lowering the potential for odor generation. Simultaneously, it removes existing odorous substances through oxidation treatment, achieving comprehensive odor control throughout the entire process. Compared to existing passive deodorization methods that only use adsorption devices at the end, this invention's active-passive synergistic deodorization mechanism significantly improves deodorization efficiency and operational stability.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention has high oil separation efficiency. After processing by the present invention, the oil separation rate in kitchen waste reaches more than 98.5%, the water content of the separated oil is less than 2.0%, and the impurity content is less than 0.5%, which can be directly used as raw material for biodiesel production.

[0022] (2) The present invention has good deodorization effect. The concentration of malodorous gas at the total outlet of the system is lower than the first-level standard limit in the "Emission Standard for Malodorous Pollutants" (GB14554-93). The removal rate of hydrogen sulfide is over 99%, the removal rate of ammonia is over 98%, and the removal rate of volatile organic compounds is over 95%.

[0023] (3) The processing cost of the present invention is extremely low. As the present invention adopts an integrated design, it reduces the equipment footprint and operation and maintenance costs. Compared with the prior art, the unit processing energy consumption is reduced by 25-35%, and the reagent consumption is reduced by 30-40%.

[0024] (4) The present invention has a high degree of resource utilization. The separated oil can be utilized as a resource. The treated water quality meets the standard of "Water Quality for Industrial Water Reuse of Urban Wastewater" (GB / T19923-2005) and can be reused for equipment cleaning and conditioning, realizing the recycling of water resources. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the integrated process for efficient separation and deodorization of kitchen waste grease in this invention; Figure 2 This is a comparison chart of the oil separation efficiency between the embodiments and comparative examples of the present invention; Figure 3 This is a comparison chart showing the odor removal effects of embodiments and comparative examples of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Example 1: This example provides an integrated process for efficient separation and deodorization of grease in kitchen waste, such as... Figure 1 As shown, the specific steps are as follows: Kitchen waste collected from a catering district had a moisture content of 78.6%, an oil content of 15.3%, a crude fiber content of 4.2%, and other impurities content of 1.9%.

[0028] Step 1: Pretreatment and Crushing / Conditioning: Kitchen waste is transported to the crushing and conditioning unit, where it is crushed to a particle size ≤8mm using a twin-shaft shear crusher. During the crushing process, a compound conditioning agent is added to the material via a metering pump at a dosage of 1.2% of the material's mass. The compound conditioning agent consists of citric acid, sodium chloride, and lipase in a mass ratio of 3:2:0.8. Simultaneously, the material temperature is controlled at 48-52℃ using jacket heating, and the pH value is adjusted to 6.0-6.2 by adding citric acid. The conditioning process takes 15 minutes.

[0029] Step 2, Cyclone-Coalescing Coupling Separation: The conditioned material is pumped into the cyclone-coalescing coupling separation unit. The inlet pressure of this unit is controlled at 0.25-0.30 MPa, and the cyclone generator produces a cyclone velocity gradient of 350 s⁻¹. -1The coalescing separation plate assembly is composed of 5 layers of corrugated plates stacked together, with a plate spacing of 8mm. The plate surface is coated with a modified silica-PTFE composite coating with a thickness of 50μm, a water contact angle of 145°, and an oil contact angle of 8°. The material residence time in the separation unit is 6 minutes. The upper oil layer is collected by an automatic oil skimmer, and the lower aqueous phase is discharged for subsequent processing.

[0030] Step 3, Synergistic Oxidation Deodorization Treatment: In the aqueous phase treatment, the separated aqueous phase is pumped into a gas-liquid mixing reactor, and an ozone-micro-nano bubble mixture is generated through a pressure dissolved gas-shear composite generator. The ozone dosage is 50 mg / L, the average particle size of the micro-nano bubbles is 450 nm, the gas-liquid volume ratio is 1:10, the hydraulic residence time is 20 min, and the reaction temperature is controlled at 45℃. Oil phase treatment: The separated oil phase is sent to an ion hydrolysis-catalytic oxidation combined unit. The unit is filled with a titanium-based supported catalyst with a mass ratio of MnO2:CeO2:Pt=7:3:0.8 and a packing density of 0.45g / cm³. The treatment temperature is 60℃ and the hydraulic retention time is 20min.

[0031] Step 4, Deep Purification and Discharge: The water phase treated in Step 3 is discharged or reused after being filtered through a multi-media filter. The water phase is filtered through a multi-media filter with quartz sand, activated carbon and zeolite as the filter media, with the three layers in a height ratio of 2:1:1 and a filtration speed of 10m / h. The treated oil phase is collected as a biodiesel feedstock after refining.

[0032] Example 2: An integrated process for efficient separation and deodorization of kitchen waste grease. The raw material is kitchen waste collected from a large canteen, with a moisture content of 72.3%, an grease content of 19.8%, a crude fiber content of 5.1%, and other impurities content of 2.8%. It is basically the same as Example 1, except that: The compound conditioning agent is added at 1.5% of the material mass, and the mass ratio of citric acid, sodium chloride, and lipase is 4:2.5:1.0. The conditioning temperature is 55-58℃ and the pH value is 5.8-6.0.

[0033] The swirl velocity gradient was adjusted to 280s. -1 The coalescing separation plate assembly uses 7 layers of corrugated plates with a plate spacing of 6mm and a coating thickness of 80μm.

[0034] The ozone dosage was 65 mg / L, the micro-nano bubble particle size was 350 nm, the gas-liquid ratio was 1:8, and the hydraulic retention time was 25 min.

[0035] The catalyst packing density was 0.5 g / cm³, the oil phase treatment temperature was 65℃, and the hydraulic residence time was 25 min.

[0036] Comparative Example 1 uses the apparatus and process described in CN213671052U. This apparatus includes a pulverizing mechanism, a solid-liquid separation mechanism, an oil-water separation mechanism using baffles and separation plates for gravity separation, and an activated carbon deodorizing plate. The raw materials used are the same as in Example 1.

[0037] Comparative Example 2 was processed using the process described in CN105296165A, employing a two-stage centrifugal separation method for oil separation and activated carbon adsorption for deodorization at the end. The raw materials used were the same as in Example 2.

[0038] Examples 1 and 2, and Comparative Examples 1 and 2, were run continuously for 72 hours. Sampling and testing were conducted to assess the oil separation effect: the feed oil content, the moisture content of the separated oil, and the oil content of the effluent were determined using a gravimetric method, and the oil separation rate was calculated. The test results are shown in Table 1. Table 1

[0039] From Table 1 and Figure 2 The comparison chart of oil separation efficiency shows that the oil separation rates of Examples 1 and 2 of this invention reached 98.7% and 98.2% respectively, significantly higher than 85.6% of Comparative Example 1 and 92.3% of Comparative Example 2. Simultaneously, the water content of the separated oil was significantly reduced, and the separation time was greatly shortened. This indicates that the cyclone-coalescence coupling separation technology of this invention has the advantages of high efficiency and speed.

[0040] Odor removal effect test: The concentration of odorous gases before and after treatment was determined by gas chromatography, and the removal rate was calculated. The test results are shown in Table 2.

[0041] Table 2

[0042] Table 2 and Figure 3 The comparison chart of odor removal effects shows that the odor removal rate of the embodiment of the present invention is significantly better than that of the comparative example. The odor concentration at the total outlet is far below the Class I limit of 30 mg / m³ of the "Odor Pollutant Emission Standard" (GB14554-93), while the comparative example can only reach the Class II or Class III standard. The reason for this is that the differentiated and synergistic deodorization design of the present invention can efficiently treat different media characteristics, and the micro-nano bubble technology significantly improves the ozone oxidation efficiency.

[0043] Stability test: Example 1 was run continuously for 30 days, with daily sampling and testing of key indicators. The results showed that the oil separation rate was stable between 97.8% and 99.1%, the hydrogen sulfide removal rate was stable between 98.5% and 99.6%, and the oil content in the effluent was ≤95mg / L. The fluctuation range of each indicator was small, indicating that the process of the present invention has good operational stability.

[0044] In summary, the integrated treatment process for efficient separation and deodorization of kitchen waste grease provided by this invention achieves efficient separation of grease and effective control of odorous gases through the integrated innovation of crushing and conditioning, cyclone coalescence coupling separation, and synergistic oxidation deodorization. The treatment effect is significantly better than that of existing technologies, and it has the outstanding advantages of high treatment efficiency, low operating cost, and high resource utilization.

[0045] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A highly efficient integrated process for separating and deodorizing grease from kitchen waste, characterized in that, Includes the following steps: Step 1, Pretreatment and Crushing / Tempering: The collected kitchen waste is transported to the crushing / tempering unit. During crushing, a compound tempering agent is added to the material. The material temperature is controlled at 40-60℃ and the pH value is 5.5-6.

5. The compound tempering agent is composed of citric acid, sodium chloride and lipase in a mass ratio of 2-5:1-3:0.5-1. Step 2, Cyclone-Coalescence Coupling Separation: The material processed in Step 1 is fed into the cyclone-coalescence coupling separation unit, which includes a cyclone generator and a coalescence separation plate assembly. Under the action of cyclone, the material forms a high-speed rotating flow field. Oil droplets migrate towards the inner wall under the action of centrifugal force, and then flow through the coalescence separation plate assembly. The surface of the coalescence separation plate assembly is provided with an oleophilic and hydrophobic coating. Small oil droplets coalesce and grow on the surface of the plate assembly and float to form an oil layer. Step 3, Synergistic Oxidation Deodorization Treatment: The aqueous phase and oil phase separated in Step 2 are deodorized separately. The aqueous phase is mixed with ozone-micro-nano bubbles through a gas-liquid mixing device. The ozone dosage is 30-80 mg / L and the micro-nano bubble particle size is 200-800 nm. The oil phase is treated by an ion hydrolysis-catalytic oxidation combined device. The treatment temperature is controlled at 50-70℃ and the hydraulic retention time is 15-30 min. Step 4, Deep Purification and Discharge: The aqueous phase after Step 3 is filtered through a multi-media system and then discharged or reused. The treated oil phase is refined and collected as a feedstock for biodiesel.

2. The integrated process for efficient separation and deodorization of kitchen waste grease as described in claim 1, characterized in that, In the swirling-coalescence coupling separation unit, the swirling velocity gradient generated by the swirling generator is 200-500s⁻¹, and the coalescence separation plate group is composed of 3-8 layers of corrugated plates with a plate spacing of 5-15mm and a micron-level groove structure on the plate surface.

3. The integrated process for efficient separation and deodorization of kitchen waste grease as described in claim 1, characterized in that, The oleophilic and hydrophobic coating is a modified silica-polytetrafluoroethylene composite coating with a thickness of 20-100 μm, a water contact angle ≥140°, and an oil contact angle ≤10°.

4. The integrated process for efficient separation and deodorization of kitchen waste grease as described in claim 1, characterized in that, In the ozone-micro / nano bubble mixing treatment, the gas-liquid volume ratio is 1:5-1:15, the micro / nano bubble generating device adopts a pressure dissolved gas-shear composite generation method, and the bubble rising speed is 0.1-0.5 mm / s.

5. The integrated process for efficient separation and deodorization of kitchen waste grease as described in claim 1, characterized in that, The ion hydrolysis-catalytic oxidation combined device is equipped with a titanium-based supported catalyst. The active components of the catalyst are a composite of MnO2, CeO2 and Pt in a mass ratio of 5-10:2-5:0.5-1, and the catalyst packing density is 0.3-0.6 g / cm³.

6. The integrated process for efficient separation and deodorization of kitchen waste grease as described in claim 1, characterized in that, The multi-media filtration uses a three-layer filter media of quartz sand, activated carbon, and zeolite, with a filter media layer height ratio of 2:1:1 and a filtration speed of 8-12 m / h.

7. The integrated process for efficient separation and deodorization of kitchen waste grease as described in claim 1, characterized in that, The dosage of the compound conditioning agent is 0.5-2.0% of the mass of kitchen waste.

8. The integrated process for efficient separation and deodorization of kitchen waste grease as described in claim 1, characterized in that, In step one, the crushing particle size of the crushing and conditioning unit is 5-10 mm, and the conditioning time is 10-20 min.

9. The integrated process for efficient separation and deodorization of kitchen waste grease according to claim 1, characterized in that, The hydraulic residence time of the cyclone-coalescence coupling separation unit in step two is 4-10 min.

10. The integrated process for efficient separation and deodorization of kitchen waste grease according to claim 1, characterized in that, The water phase after multi-media filtration in step four meets the water quality standards for industrial water reuse of urban wastewater and can be reused for conditioning and replenishment or equipment cleaning in step one.

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