Kitchen garbage wastewater treatment system

Abstract

The kitchen waste wastewater treatment system provided by the invention comprises the pretreatment system, the regulating reservoir and the biochemical system, can effectively prevent impact of high salinity of kitchen waste on the biochemical system, can directly serve as a carbon source of a sewage plant for use as effluent of the pretreatment system, and has the advantages of short process flow, small occupied area, low operation and maintenance cost, stability, standard reaching and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of kitchen waste wastewater treatment, and particularly relates to a kitchen waste wastewater treatment system. Background Art

[0002] The characteristics of the wastewater from a kitchen waste treatment plant are that the wastewater contains a large amount of grease, colloidal particles and suspended solids, and the main components are animal and vegetable oils, inorganic salts, surfactants, proteins and amino acids, etc. The main pollutant indicators in the wastewater are pH value, COD, SS, ammonia nitrogen, total nitrogen, total phosphorus, animal and vegetable oils, etc., which are wastewater with a high COD concentration and good biodegradability.

[0003] At present, the treatment processes for kitchen waste wastewater mainly adopt various treatment methods such as chemical flocculation, physical precipitation, and biodegradation, but there are generally the following problems: 1. The process flow is long and the operation difficulty is high; 2. The floor area is large and the investment cost is high; 3. The dosage of chemicals is large and the later operation and maintenance cost is high; 4. It is difficult to meet the standards stably or the utilization rate of organic resources is low. For example, the anaerobic fermentation + MBR membrane process has the advantages of high organic load-bearing capacity and effective resource utilization, but its disadvantages are large engineering investment, large floor area, complex process, large amount of biogas slurry and biogas residue generated, and high treatment difficulty; the screw press + air flotation + biochemical process has the disadvantages of long process flow, high operation difficulty, large dosage of chemicals, high later operation and maintenance cost, and at the same time, for kitchen waste wastewater with high salt content, it is easy to cause problems such as the collapse of the biochemical system. Summary of the Invention

[0004] In order to overcome the above deficiencies of the prior art, the present invention provides a kitchen waste wastewater treatment system, which has the characteristics of less investment, simple process and low operation and maintenance cost. The treated wastewater can meet the "Quality Standard for Wastewater Discharged into Urban Sewage Systems" (GB31962 - 2015) and the connection agreement standards of the downstream sewage treatment plant (CODcr ≤ 350mg / L; ammonia nitrogen ≤ 35mg / L; total nitrogen ≤ 45mg / L; total phosphorus ≤ 3mg / L).

[0005] Therefore, the specific technical solution adopted by the present invention to achieve the above purpose is as follows:

[0006] A kitchen waste wastewater treatment system includes a pretreatment system, an adjustment tank, and a biochemical system.

[0007] The pretreatment system includes a filtrate collection device, a heat exchange device, a horizontal separator, a heating device, a three-phase separation device, a sedimentation and oil removal device, an MVR device, and a cooling tower.

[0008] The filtrate collection device collects the filtrate generated by squeezing kitchen waste, is internally provided with a stirring device, and is also provided with a sludge inlet, which is connected to the sedimentation slag discharge port of the sedimentation and oil removal device and the biochemical sludge pipeline.

[0009] The described heat exchange device uses a tubular heat exchanger. The hot medium inlet is connected to the condensate pump of the MVR device, and the hot medium outlet is connected to the cooling tower; the cold medium inlet is connected to the filtrate collection device; the cold medium outlet is connected to the horizontal separation device;

[0010] Optionally, the hot medium outlet of the heat exchange device is connected to the flushing pipeline of the food waste pressing section;

[0011] Optionally, the hot medium outlet of the heat exchange device is connected to the sewage treatment plant's intake pipe.

[0012] The inlet of the described horizontal separation device is connected to the heat exchange device, and the outlet is connected to the heating device.

[0013] The described heating device uses a kettle-type heat exchanger. The hot medium inlet is connected to the steam pipeline, the cold medium inlet is connected to the horizontal separation device, and a stirring device is provided inside the heating device. The heating temperature is controlled at 80°C;

[0014] Optionally, the heating temperature of the heating device is controlled at 60°C.

[0015] The inlet of the described three-phase separation device is connected to the heating device, and the outlet is connected to the sedimentation and oil removal device;

[0016] The slag materials generated by the horizontal separation device and the three-phase separation device are transported by screw to the high-temperature aerobic device for resource utilization, and the oil generated by the three-phase separation is collected for further treatment.

[0017] The inlet of the described sedimentation and oil removal device is connected to the three-phase separation device, and the outlet is connected to the MVR device; the sedimentation and oil removal device is divided into a sludge hopper, a sedimentation area, and a clarification and oil removal area; the sediment slag outlet is connected to the sludge inlet of the filtrate collection device.

[0018] The described MVR device uses mechanical vapor recompression technology; the evaporation temperature is controlled at 80°C; the generated non-condensable gas enters the deodorization facility for treatment; the generated condensate is connected to the hot medium inlet of the heat exchange device through a condensate pump.

[0019] Optionally, the heating temperature of the MVR device is controlled at 60°C.

[0020] The described cooling tower uses a closed cooling tower. The inlet is connected to the hot medium outlet of the heat exchange device, and the outlet is connected to the inlet of the regulation tank. The temperature is controlled at 20 - 25°C.

[0021] The inside of the described regulation tank is provided with oil-absorbing cotton, and the inlet is connected to the outlet of the cooling tower; the pH adjustment chemical addition port is set at the end of the inlet pipeline, and a pipeline mixer is used for mixing;

[0022] Optionally, the inlet of the regulation tank is connected to the wastewater well generated by the flushing pipeline of the food waste pressing section.

[0023] The described biochemical system includes a denitrification device, a nitrification device, and an MBR membrane system connected in sequence; among them, the dissolved oxygen for denitrification is controlled at 0.2 - 0.5 mg / L, the temperature is controlled at 20 - 25 °C, and the residence time is controlled at 0.5 - 1.5 days; the dissolved oxygen for nitrification is controlled at 2 - 3 mg / L, the temperature is controlled at 20 - 25 °C, and the residence time is controlled at 1.5 - 3 days; the MBR membrane system uses flat membranes, the MLSS is controlled at 10000 - 12000 mg / L, and the reflux ratio is controlled at 6:1 - 10:1; the sludge generated by the biochemical system is connected to the sludge inlet of the filtrate collection device.

[0024] The technical solution of the present invention has the following advantages:

[0025] A pretreatment system for a food waste wastewater treatment system provided by the present invention, an adjustment tank, and a biochemical system have the advantages of short process flow, small floor area, low operation and maintenance cost, and stable compliance.

[0026] A pretreatment system for food waste wastewater treatment uses a filtrate collection device, a heat exchange device, a horizontal separation device, a heating device, a three-phase separation device, a sedimentation and oil removal device, an MVR device, and a cooling tower for pretreatment, and separates materials without adding chemicals, which not only reduces the operation and maintenance cost of chemicals, but also increases the output of slag materials, and is resourcefully utilized through the subsequent high-temperature aerobic fermentation device, having economic value; the condensed water generated by the MVR device has the advantages of low conductivity, high CN ratio, and good biodegradability, which can effectively prevent the impact on the biochemical system caused by the high salt content of food waste; at the same time, after the condensed water is recycled to the front section for preheating of materials, it can be used for flushing the facilities and floor oil stains, or directly used as a carbon source for the sewage treatment plant.

[0027] An adjustment tank for food waste wastewater treatment is internally provided with oil-absorbing cotton, which can prevent the impact of the oil brought in by the flushing of the floor oil stains on the subsequent biochemical system.

[0028] A biochemical system for food waste wastewater treatment includes a denitrification device, a nitrification device, and an MBR membrane system, with a short overall residence time, and the generated sludge is connected to the filtrate collection device without secondary pressure filtration. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the process flow diagram of the present invention

[0030] Figure 2 It is the process flow diagram of Embodiment 1 of the present invention

[0031] Figure 3 It is the process flow diagram of Embodiment 2 of the present invention

[0032] Figures 4 - 8 It is the water quality test report of the MVR device of the present invention DETAILED DESCRIPTION OF THE INVENTION

[0033] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains.

[0034] Example 1

[0035] A kitchen waste wastewater treatment system includes a pretreatment system, an adjustment tank, and a biochemical system.

[0036] The pretreatment system adopts a filtrate collection device, a heat exchange device, a horizontal separator, a heating device, a three-phase separation device, a sedimentation and oil removal device, an MVR device, and a cooling tower.

[0037] The filtrate collection device mainly collects the filtrate of the kitchen waste pressure filtration system. A stirring device is provided inside the filtrate collection device, and at the same time, a sludge inlet is provided, which is connected to the sedimentation slag outlet of the sedimentation and oil removal device and the biochemical sludge pipeline, and is controlled by liquid level and flow regulation.

[0038] The heat exchange device adopts a tubular heat exchanger. The hot medium inlet is connected to the condensate pump of the MVR device, the hot medium outlet is connected to the cooling tower, the cold medium inlet is connected to the filtrate collection device, and the cold medium outlet is connected to the horizontal separation device. By exchanging heat with the MVR condensate, the energy consumption is reduced, and at the same time, the separation effect of the horizontal separator is improved, especially in winter; at the same time, the hot medium outlet of the heat exchange device is connected to the flushing pipeline of the kitchen waste pressing section for flushing the facilities and the ground oil stains, saving the consumption of tap water and improving the oil stain removal effect at the same time.

[0039] The inlet of the horizontal separation device is connected to the heat exchange device, and the outlet is connected to the heating device for solid-liquid separation to remove large particle solids in the wastewater. The slag is transported to the high-temperature aerobic device through a screw for resource utilization, and the liquid part enters the heating device;

[0040] The heating device adopts a kettle-type heat exchanger. The hot medium inlet is connected to the steam pipeline, the cold medium inlet is connected to the horizontal separation device, and a stirring device is provided inside the heating device. The heating temperature is controlled at 80°C.

[0041] The wastewater from the heating device enters the three-phase separation device for three-phase separation. The rotation speed of the three-phase separation device is 3000 r / min. The oil generated by the three-phase separation device is collected for further resource utilization; the slag generated by the three-phase separation is transported to the high-temperature aerobic device through a screw for resource utilization; the liquid generated by the three-phase separation device enters the sedimentation and oil removal device. Most of the solids and oil can be removed through the three-phase separation device.

[0042] The inlet of the sedimentation and oil removal device is connected to the three-phase separation device, and the outlet is connected to the MVR device; the sedimentation and oil removal device is divided into a sludge hopper, a sedimentation area, and a clarification and oil removal area; the sedimentation area uses inclined plates to enhance the sedimentation effect of suspended solids, and the clarification and oil removal area uses filter cotton for oil removal. The supernatant enters the MVR evaporation system, and the sediment residue is connected to the sludge inlet of the filtrate collection device.

[0043] The MVR device adopts mechanical vapor recompression technology; the evaporation temperature is controlled at 80°C; the non-condensable gas generated is condensed by a condenser and then extracted by a vacuum pump and sent to the deodorization facility for treatment; the generated condensate is connected to the heat exchange device through a condensate pump. After MVR concentration, the ammonia nitrogen, total nitrogen, CODcr, and total salt content indicators in the wastewater can be significantly reduced, reducing the load on the biochemical system and the impact of high salinity.

[0044] The cooling tower adopts a closed cooling tower. The inlet heat exchange device is connected to the hot medium outlet, and the outlet is connected to the inlet of the regulation tank; the temperature of the cooling tower is controlled at 20 - 25°C.

[0045] The inlet of the regulation tank is connected to the outlet of the cooling tower and the wastewater well generated by the flushing pipeline of the kitchen waste pressing section; the pH adjustment chemical addition port is set at the end of the inlet pipeline and mixed by a pipeline mixer; there is absorbent cotton inside the regulation tank to prevent the oil in the wastewater generated by the flushing pipeline of the kitchen waste pressing section from entering the subsequent biochemical system.

[0046] The biochemical system includes a denitrification device, a nitrification device, and an MBR membrane system connected in sequence; among them, the dissolved oxygen in denitrification is controlled at 0.2 - 0.5 mg / L, the temperature is controlled at 20 - 25°C, and the residence time is controlled at 1.5 days; the dissolved oxygen in nitrification is controlled at 2 - 3 mg / L, the temperature is controlled at 20 - 25°C, and the residence time is controlled at 3 days; the MBR membrane system uses flat membranes, the MLSS is controlled at 10000 - 12000 mg / L, and the reflux ratio is controlled at 10:1; the sludge generated by the biochemical system is connected to the sludge inlet of the filtrate collection device.

[0047] The treated wastewater can meet the "Quality Standard for Wastewater Discharged into Municipal Sewers" (GB31962 - 2015) and the takeover agreement standard of the downstream sewage treatment plant (CODcr ≤ 350 mg / L; ammonia nitrogen ≤ 35 mg / L; total nitrogen ≤ 45 mg / L; total phosphorus ≤ 3 mg / L).

[0048] Tests were conducted on a certain kitchen waste plant (200 t / d), and the comparison of water quality data before and after treatment is shown in Table 1

[0049]

[0050] As can be seen from Table 1, a kitchen waste wastewater treatment system of the present invention includes a pretreatment system, an adjustment tank, and a biochemical system. For the treatment of kitchen waste wastewater with high CODcr and high salinity, it can meet the "Quality Standards for Wastewater Discharged into Urban Sewage Systems" (GB31962-2015) and the takeover agreement standards of downstream sewage treatment plants (CODcr ≤ 350 mg / L; ammonia nitrogen ≤ 35 mg / L; total nitrogen ≤ 45 mg / L; total phosphorus ≤ 3 mg / L).

[0051] The comparison of water quality data before and after the MVR system processes the wastewater without a sedimentation and oil removal device is shown in Table 2

[0052]

[0053] As can be seen from Table 2, the MVR system section of a kitchen waste wastewater treatment system of the present invention can efficiently remove indicators such as CODcr, ammonia nitrogen, total nitrogen, and total salt content.

[0054] An experiment was conducted on a certain kitchen waste plant (200 t / / d). The comparison of process and chemical agent data between the present invention and other processes is shown in Table 3

[0055]

[0056] As can be seen from Table 3, compared with the usage amount and cost of chemical agents in the spiral press + air flotation process, a kitchen waste wastewater treatment system of the present invention can greatly reduce the dosage of chemical agents and save 73.8 yuan per ton of water in cost.

[0057] Example 2

[0058] A kitchen waste wastewater treatment system includes a pretreatment system, an adjustment tank, and a biochemical system.

[0059] The pretreatment system adopts a filtrate collection device, a heat exchange device, a horizontal separator, a heating device, a three-phase separation device, a sedimentation and oil removal device, an MVR device, and a cooling tower.

[0060] The filtrate collection device mainly collects the filtrate of the kitchen waste pressure filtration system. A stirring device is provided inside the filtrate collection device, and at the same time, a sludge inlet is provided, which is connected to the sediment slag outlet of the sedimentation and oil removal device and the biochemical sludge pipeline, and is controlled by liquid level and flow regulation.

[0061] The heat exchange device adopts a tubular heat exchanger. The hot medium inlet is connected to the condensate pump of the MVR device, and the hot medium outlet is connected to the sewage plant intake pipe and used as a carbon source for the sewage plant; the cold medium inlet is connected to the filtrate collection device, and the cold medium outlet is connected to the horizontal separation device. By exchanging heat with the MVR condensate water, the energy consumption is reduced, and at the same time, the separation effect of the horizontal separator is improved, especially in winter.

[0062] The inlet of the horizontal separation device is connected to the heat exchange device, and the outlet is connected to the heating device for solid-liquid separation to remove large particulate solids in the wastewater. The slag is conveyed by a screw to the high-temperature aerobic device for resource utilization, and the liquid part enters the heating device;

[0063] The heating device adopts a kettle-type heat exchanger. The hot medium inlet is connected to the steam pipeline, and the cold medium inlet is connected to the horizontal separation device. A stirring device is arranged inside the heating device, and the heating temperature is controlled at 60°C.

[0064] The wastewater from the heating device enters the three-phase separation device for three-phase separation. The rotation speed of the three-phase separation device is 3000 r / min. The oil generated by the three-phase separation device is collected for further resource utilization; the solid part generated by the three-phase separation is conveyed by a screw to the high-temperature aerobic device for resource utilization; the liquid generated by the three-phase separation device enters the sedimentation and oil removal device. Through the three-phase separation device, most of the solids and oil can be removed.

[0065] The inlet of the sedimentation and oil removal device is connected to the three-phase separation device, and the outlet is connected to the MVR device; the sedimentation and oil removal device is divided into a sludge hopper, a sedimentation area, and a clarification and oil removal area; inclined plates are used in the sedimentation area to enhance the sedimentation effect of suspended solids, and filter cotton is used in the clarification and oil removal area for oil removal. The supernatant enters the MVR evaporation system, and the sediment slag is connected to the sludge inlet of the filtrate collection device.

[0066] The MVR device adopts mechanical vapor recompression technology; the evaporation temperature is controlled at 60°C; the generated non-condensable gas is condensed by a condenser and then pumped out by a vacuum pump and enters the deodorization facility for treatment; the generated condensed water is connected to the heat exchange device through a condensate pump. After MVR concentration, the ammonia nitrogen, total nitrogen, CODcr, and total salt content indexes in the wastewater can be greatly reduced and can be used as a carbon source.

[0067] The indexes of the effluent of the MVR device as a carbon source are shown in Table 4

[0068]

[0069] The inlet of the regulation tank is connected to the wastewater well generated by the flushing pipeline of the garbage pressing section; the pH adjustment chemical addition port is set at the end of the inlet pipeline, and a pipeline mixer is used for mixing; an oil-absorbing cotton is arranged inside the regulation tank to prevent the oil in the wastewater generated by the flushing pipeline of the kitchen waste pressing section from entering the subsequent biochemical system.

[0070] The biochemical system includes a denitrification device, a nitrification device, and an MBR membrane system connected in sequence; among them, the dissolved oxygen in denitrification is controlled at 0.2 - 0.5 mg / L, the temperature is controlled at 20 - 25 °C, and the residence time is controlled at 0.5 days; the dissolved oxygen in nitrification is controlled at 2 - 3 mg / L, the temperature is controlled at 20 - 25 °C, and the residence time is controlled at 1.5 days; the MBR membrane system uses flat membranes, the MLSS is controlled at 10000 - 12000 mg / L, and the reflux ratio is controlled at 6:1; the sludge generated by the biochemical system is connected to the sludge inlet of the filtrate collection device.

[0071] The treated wastewater discharged can meet the "Quality Standard for Wastewater Discharged into Urban Sewers" (GB31962 - 2015) and the takeover agreement standards of the downstream sewage treatment plant (CODcr ≤ 350 mg / L; ammonia nitrogen ≤ 35 mg / L; total nitrogen ≤ 45 mg / L; total phosphorus ≤ 3 mg / L).

Claims

1. A kitchen waste wastewater treatment system includes a pretreatment system, an adjustment tank, and a biochemical system.

2. The preprocessing system according to claim 1, characterized in that: It also includes a filtrate collection device, a heat exchange device, a horizontal separator, a heating device, a three-phase separation device, a sedimentation and oil removal device, an MVR device, and a cooling tower.

3. The pretreatment system according to claim 2, wherein: The filtrate collection device collects the filtrate generated by squeezing kitchen waste, has a sludge inlet, and is connected to the sedimentation residue outlet of the sedimentation and oil removal device and the biochemical sludge pipeline.

4. The pretreatment system according to claim 2, wherein: The heat medium inlet of the heat exchange device is connected to the condensate water pump of the MVR device, and the heat medium outlet is connected to the cooling tower / the flushing pipeline of the kitchen waste squeezing section / the sewage plant intake pipe connection.

5. The pretreatment system according to claim 4, wherein: The cold medium inlet is connected to the filtrate collection device; the cold medium outlet is connected to the horizontal separation device.

6. The pretreatment system according to claim 2, wherein: The heating temperature of the heating device is controlled at 60 °C or 80 °C.

7. The pretreatment system according to claim 2, characterized in that: The evaporation temperature of the MVR device is controlled at 60 °C or 80 °C.

8. The biochemical system according to claim 1, wherein: It also includes a denitrification device, a nitrification device, and an MBR membrane system.

9. The biochemical system according to claim 8, characterized in that: The dissolved oxygen for denitrification is controlled at 0.2 - 0.5 mg / L, the temperature is controlled at 20 - 25 °C, and the residence time is controlled at 0.5 - 1.5 days; the dissolved oxygen for nitrification is controlled at 2 - 3 mg / L, the temperature is controlled at 20 - 25 °C, and the residence time is controlled at 1.5 - 3 days; the MBR membrane system uses flat membranes, the MLSS is controlled at 10000 - 12000 mg / L, and the reflux ratio is controlled at 6:1 - 10:1; The sludge generated by the biochemical system is connected to the sludge inlet of the filtrate collection device.

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