Leather processing wastewater treatment system

Abstract

The utility model discloses a leather processing wastewater treatment system which comprises a physicochemical pretreatment unit, a biochemical treatment unit, an advanced treatment unit and a sludge treatment unit which are arranged in sequence, and the physicochemical pretreatment unit comprises a grating tank, a grit chamber, an aeration regulating tank and an air flotation machine which are arranged in sequence; the biochemical treatment unit comprises a first-stage A / O tank, a first-stage sedimentation tank, a second-stage A / O tank and a second-stage sedimentation tank which are sequentially arranged; the deep treatment unit comprises a Fenton oxidation reaction zone and a final sedimentation tank which are arranged in sequence; the sludge treatment unit comprises a sludge concentration tank, a sludge flocculation dosing device, a sludge screw pump and a sludge dewatering machine. By combining physicochemical treatment, biochemical treatment and deep oxidation treatment, the leather processing wastewater treatment device has the advantages of high impact load resistance, high treatment efficiency, stable effluent quality, low operation cost and the like, and can effectively treat leather processing wastewater.

Description

Technical Field

[0001] The utility model relates to a leather processing wastewater treatment system, which belongs to the field of environmental protection technology. Background Art

[0002] Leather-making sewage is one of the important pollution sources of water environmental pollution and is also known as one of the "three major wastewaters" (paper-making wastewater, printing and dyeing wastewater, leather-making wastewater).

[0003] The leather processing wastewater mainly comes from three stages: preparation, tanning and finishing. The wastewater discharged in the pretreatment preparation stage is strongly alkaline, accounting for about 65% of the total drainage volume, mainly including the following parts: the raw hide washing water containing high-concentration Cl-, the degreasing wastewater containing a large amount of grease and its saponified products, and the alkaline hair removal and liming wastewater containing sulfides. The tanning stage mainly discharges weakly acidic chromium-tanning wastewater containing Cr3+ and dyeing wastewater. The chromium-tanning wastewater accounts for about 30% of the total water volume and contains a large amount of neutral salts. The dyeing wastewater only accounts for 1-5% of the total water volume. Among them, the most polluted are the degreasing wastewater, alkaline hair removal and liming wastewater, and chromium-tanning wastewater. The comprehensive leather-making wastewater is alkaline, has strong biological toxicity, a high content of refractory substances, dirty water quality and a bad smell.

[0004] The main characteristics of the leather processing wastewater are as follows: (1) The leather processing wastewater is high-concentration organic wastewater with very high COD and BOD concentrations in the wastewater; (2) The leather wastewater has a strong smell, mainly caused by the decomposition of sulfides and proteins; (3) The leather processing wastewater has strong biological toxicity, mainly from high-concentration sulfides and trivalent chromium. Sodium sulfide is used for hair removal and chromium salts are used for tanning. The content of chromium and sulfides in the waste chromium liquor can reach thousands of milligrams per liter; (4) The SS content in the leather processing wastewater is relatively high, reaching more than 3000 mg / L; (5) The chromaticity of the leather processing wastewater is mainly caused by dyes and tanning agents, and the chromaticity of the wastewater is 600-3000 times; (6) The leather-making wastewater is generally alkaline, mainly from lime, caustic soda, and sodium sulfate used in processes such as hair removal, and the pH value is often 9-10; (7) The chloride and sulfate concentrations in the leather-making wastewater are 2000-3000 mg / L, mainly from the processes of raw hide preservation, pickling, and tanning.

[0005] Therefore, in view of the above problems, there is an urgent need to propose a treatment method with low cost, good comprehensive treatment effect, and adaptability to large fluctuations in water volume and water quality. Content of the Utility Model

[0006] In view of this, the utility model provides a leather processing wastewater treatment system, adopting a process combining "pretreatment + biochemical treatment + advanced oxidation and deep treatment" to achieve effective treatment of leather processing wastewater.

[0007] To solve the above technical problems, a technical solution adopted by the present utility model is: a leather processing wastewater treatment system, which includes a physical and chemical pretreatment unit, a biochemical treatment unit, a deep treatment unit, and a sludge treatment unit arranged in sequence. The physical and chemical pretreatment unit includes a grid tank, a grit chamber, an aeration adjustment tank, and a flotation machine arranged in sequence; the biochemical treatment unit includes a first-stage A / O tank, a first-stage sedimentation tank, a second-stage A / O tank, and a second-stage sedimentation tank arranged in sequence; the deep treatment unit includes a Fenton oxidation reaction zone and a final sedimentation tank arranged in sequence; the sludge treatment unit includes a sludge thickening tank, a sludge flocculation dosing device, a sludge screw pump, and a sludge dehydrator; wherein, the grid tank is arranged at the forefront of the leather processing wastewater treatment system, shares a wall with the grit chamber, and is connected through holes on the pool wall. A rotary mechanical grid is arranged in the grid tank; a sand storage hopper is arranged at the bottom of the grit chamber, and a sand discharge pump is arranged in the hopper; the aeration adjustment tank is connected to the grit chamber through a hole. The aeration adjustment tank is provided with a float level gauge and a sewage lift pump, and a perforated aeration system is arranged at the bottom, which is connected to a blower through a pipeline; the sewage lift pump of the aeration adjustment tank is connected to the flotation machine through a pipeline. An online pH meter and a pipeline mixer are installed in sequence on the connecting pipeline. The pipeline mixer is connected to an alkali dosing device; the flotation machine is connected to a PAC dosing device and a PAM dosing device through pipelines. The water outlet of the flotation machine is connected to the first-stage A tank through a pipeline; the first-stage A tank, the first-stage O tank, the first-stage sedimentation tank, the second-stage A tank, the second-stage O tank, the second-stage sedimentation tank, and the Fenton oxidation reaction zone are arranged adjacent to each other in sequence, share a pool wall, and through holes are opened on the pool wall for sequential connection; Soft fillers and submersible mixers are arranged in the first-stage A tank and the second-stage A tank; Soft fillers are arranged inside the first-stage O tank and the second-stage O tank, and microporous tube aerators with check valves are arranged at the bottom, which are connected to a Roots blower through a pipeline; Inclined tube fillers are arranged in the first-stage sedimentation tank and the second-stage sedimentation tank, and overflow weirs are arranged around the top of the tank; The Fenton oxidation reaction zone is divided into five grids, which are connected through overflow holes. The first grid reaction zone is connected to an acid dosing device through a pipeline, and an online pH meter is arranged in the reaction zone. The second grid reaction zone is connected to a ferrous sulfate dosing device through a pipeline. The third grid reaction zone is connected to a hydrogen peroxide dosing device through a pipeline. The fourth grid reaction zone is connected to an alkali dosing device through a pipeline, and an online pH meter is arranged in the reaction zone. The fifth grid reaction zone is connected to a PAM dosing device through a pipeline. Stirring devices are arranged in all five grid reaction zones; The final sedimentation tank is a vertical flow sedimentation tank, with a draft tube arranged in the center and overflow weirs arranged around; Sludge pumps are arranged in the first-stage sedimentation tank, the second-stage sedimentation tank, and the final sedimentation tank, and are connected to the sludge thickening tank through pipelines; One end of the sludge screw pump is connected to the sludge thickening tank through a pipeline, and this section of the pipeline is also connected to the sludge flocculation dosing device through a dosing pipeline, and the other end is connected to the sludge dehydrator;The sludge thickening tank is connected to the sludge pipelines for connecting the grit chamber, the flotation machine, the primary sedimentation tank, the secondary sedimentation tank, and the final sedimentation tank. The upper-layer wastewater is connected to the aeration adjustment tank through a return pipe.

[0008] Furthermore, the PAC dosing device, the acid dosing device, the ferrous sulfate dosing device, the hydrogen peroxide dosing device, and the sludge flocculation dosing device are of the single-barrel two-pump skid-mounted type. The alkali dosing device and the PAM dosing device are of the single-barrel three-pump skid-mounted type. Stirrers are installed on the tops of the barrels of the PAC dosing device, the ferrous sulfate dosing device, the alkali dosing device, the PAM dosing device, and the sludge flocculation dosing device.

[0009] Furthermore, mixed liquor return pumps are respectively arranged in the primary O tank and the secondary O tank. The mixed liquor return pump of the primary O tank is connected to the primary A tank through a pipeline, and the mixed liquor return pump of the secondary O tank is connected to the secondary A tank through a pipeline.

[0010] Furthermore, the sludge pump of the primary sedimentation tank is connected to the primary A tank and the primary O tank through pipelines, and the sludge pump of the secondary sedimentation tank is connected to the secondary A tank and the secondary O tank through pipelines.

[0011] The beneficial effects of the present utility model are as follows: By adopting the process combining "pretreatment + biochemical treatment + advanced oxidation and deep treatment", the treatment effect is good, maximizing the self-metabolism of microorganisms, with low operating costs, and being able to effectively treat leather processing wastewater. Description of the Drawings

[0012] Figure 1 is the structural schematic diagram of the present utility model.

[0013] In the figure, 1. Grid tank, 1.1 Rotating mechanical grid, 2. Grit chamber, 2.1 Sand discharge pump

[0014] 3. Aeration Regulation Tank 3.1. Float Level Gauge 3.2. Perforated Aeration System in the Aeration Regulation Tank 3.3. Sewage Lift Pump in the Aeration Regulation Tank 3.4. Pipe Mixer 3.5. Alkali Dosing Device 4. Flotation Machine 4.1. PAC Dosing Device 4.2. PAM Dosing Device 5. First - level A Tank 5.1. Soft Packing in the First - level A Tank 5.2. Submersible Mixer in the First - level A Tank 6. First - level O Tank 6.1. Soft Packing in the First - level O Tank 6.2. Micro - pore Tube Aerator in the First - level O Tank 6.3. Mixed - liquor Return Pump in the First - level O Tank 7. First - level Sedimentation Tank 7.1. Inclined Tube Packing in the First - level Sedimentation Tank 7.2. Overflow Weir in the First - level Sedimentation Tank 7.3. Sludge Pump in the First - level Sedimentation Tank 8. Second - level A Tank 8.1. Soft Packing in the Second - level A Tank 8.2. Submersible Mixer in the Second - level A Tank 9. Second - level O Tank 9.1. Soft Packing in the Second - level O Tank 9.2. Micro - pore Tube Aerator in the Second - level O Tank 9.3. Mixed - liquor Return Pump in the Second - level O Tank 10. Second - level Sedimentation Tank 10.1. Inclined Tube Packing in the Second - level Sedimentation Tank 10.2. Overflow Weir in the Second - level Sedimentation Tank 10.3. Sludge Pump in the Second - level Sedimentation Tank 11. First Reaction Zone 11.1. Stirring Device in the First Reaction Zone 11.2. Acid Dosing Device 11.3. On - line pH Meter in the First Reaction Zone 12. Second Reaction Zone 12.1. Stirring Device in the Second Reaction Zone 12.2. Ferrous Sulfate Dosing Device 13. Third Reaction Zone 13.1. Stirring Device in the Third Reaction Zone 13.2. Hydrogen Peroxide Dosing Device 14. Fourth Reaction Zone 14.1. Stirring Device in the Fourth Reaction Zone 14.2. On - line pH Meter in the Fourth Reaction Zone 15. Fifth Reaction Zone 15.1. Stirring Device in the Fifth Reaction Zone 16. Final Sedimentation Tank 16.1. Central Flow - guiding Cylinder 16.2. Overflow Weir in the Final Sedimentation Tank 16.3. Sludge Pump in the Final Sedimentation Tank 17. Sludge Thickening Tank 17.1. Sludge Screw Pump 17.2. Sludge Dewatering Machine 17.3. Sludge Flocculation Dosing Device 18. Blower Detailed Implementation Manner

[0015] The following further describes the specific implementation mode of the present utility model in combination with the attached drawings through specific implementation examples. A leather processing wastewater treatment system of the present utility model includes a physical and chemical pretreatment unit, a biochemical treatment unit, a deep treatment unit, and a sludge treatment unit arranged in sequence. The physical and chemical pretreatment unit includes a grid tank 1, a grit chamber 2, an aeration adjustment tank 3, and a flotation machine 4 arranged in sequence; the biochemical treatment unit includes a first-stage A / O tank and a first-stage sedimentation tank 7, and a second-stage A / O tank and a second-stage sedimentation tank 10 arranged in sequence; the deep treatment unit includes a Fenton oxidation reaction zone and a final sedimentation tank 16 arranged in sequence; the sludge treatment unit includes a sludge thickening tank 17, a sludge flocculation dosing device 17.3, a sludge screw pump 17.1, and a sludge dewatering machine 17.2; the leather processing wastewater flows in from one side of the grid tank 1, flows through the rotary grid 1.1, filters out larger floating objects, and then flows into the grit chamber 2 by gravity. The sand grains and other impurities contained in the sewage precipitate in the bottom sand storage hopper of the tank, and the supernatant flows into the aeration adjustment tank 3 by gravity. After the wastewater adjusts the water quality and equalizes the water volume in the aeration adjustment tank 3, it is pumped to the flotation machine 4 by the sewage lift pump 3.3 of the aeration adjustment tank. In the flotation machine 4, the SS in the wastewater reacts with the added PAC and PAM to form flocs, which combine with the microbubbles generated by flotation to form scum and are scraped off. The effluent flows into the biochemical treatment unit by gravity. The biochemical treatment unit adopts a two-stage AO process, and uses the self-metabolism of microorganisms to remove most of the organic pollutants, and then the effluent flows into the first grid reaction zone 11 of Fenton by gravity. After the sewage adjusts the pH to an acidic state here, the sewage flows into the second grid reaction zone 12 by gravity. After the sewage reacts with the added ferrous sulfate here, it flows into the third grid reaction zone 13 by gravity. Here, the added hydrogen peroxide reacts with the Fe 2+ in the sewage to generate strongly oxidizing [•OH], which destroys the groups in the wastewater to achieve the purpose of degrading pollutants. Then the wastewater flows into the fourth grid reaction zone 14 by gravity, reacts with the added alkali, and then flows into the fifth grid reaction zone 15. The wastewater reacts with the added PAM to generate a large amount of flocs, and then flows into the final sedimentation tank 16 by gravity. Stirring devices are installed in each Fenton oxidation reaction zone to accelerate the mixing speed of the reagent and the sewage and shorten the reaction time. The reacted flocs sink to the bottom mud hopper under the action of gravity, and the supernatant is discharged up to the standard. The sludge in the sludge thickening tank 17 is pumped to the sludge dewatering machine 17.2 by the sludge screw pump 17.1 for pressure filtration and dehydration. The dehydrated sludge is transported out, and the filtrate enters the aeration adjustment tank 3 through a return pipe to avoid secondary pollution.

[0016] The above is only the preferred specific implementation mode of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model, according to the technical solution and inventive concept of the present utility model, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present utility model.

Claims

1. A leather processing wastewater treatment system, characterized in that: It includes a physicochemical pretreatment unit, a biochemical treatment unit, a deep treatment unit, and a sludge treatment unit, which are arranged in sequence. The physicochemical pretreatment unit includes a grille tank, a grit tank, an aeration adjustment tank, and an air flotation machine, which are arranged in sequence; the biochemical treatment unit includes a primary A / O tank, a primary sedimentation tank, a secondary A / O tank, and a secondary sedimentation tank, which are arranged in sequence; the deep treatment unit includes a Fenton oxidation reaction zone and a final sedimentation tank, which are arranged in sequence; the sludge treatment unit includes a sludge thickening tank, a sludge flocculation and dosing device, a sludge screw pump, and a sludge dewatering machine; wherein the grille tank is arranged at the front end of the leather processing wastewater treatment system, shares a wall with the grit tank, and is connected through holes on the tank wall, and a rotary mechanical grille is arranged in the grille tank; the bottom of the grit tank A sand storage hopper is arranged at the bottom, and a sand discharge pump is arranged in the hopper; the aeration regulating tank is connected to the sand settling tank through holes, a float level gauge and a sewage lifting pump are arranged in the aeration regulating tank, a perforated aeration system is arranged at the bottom, and the blower is connected through a pipeline; the sewage lifting pump in the aeration regulating tank is connected to the flotation machine through a pipeline, and an online pH meter and a pipeline mixer are installed on the pipeline in sequence, and the pipeline mixer is connected to the alkali dosing device; the flotation machine is connected to the PAC dosing device and the PAM dosing device through a pipeline, and the effluent of the flotation machine is connected to the primary A tank through a pipeline; the primary A tank, the primary O tank, the primary sedimentation tank, the secondary A tank, the secondary O tank, the secondary sedimentation tank, and the Fenton oxidation reaction zone are arranged adjacent to each other in sequence, The pool wall is used, and through holes are opened on the pool wall to connect in sequence; the first-level A pool and the second-level A pool are provided with soft fillers and submersible mixers; the first-level O pool and the second-level O pool are provided with soft fillers inside, and a microporous tubular aerator with a check device is provided at the bottom, which is connected to the Roots blower through a pipeline; the first-level sedimentation tank and the second-level sedimentation tank are provided with inclined tube fillers, and overflow weirs are provided around the top of the pool; the Fenton oxidation reaction zone is divided into five grids, which are respectively connected through flow holes, the first grid reaction zone is connected to the acid dosing device through a pipeline, and an online pH meter is provided in the reaction zone, the second grid reaction zone is connected to the ferrous sulfate dosing device through a pipeline, the third grid reaction zone is connected to the hydrogen peroxide dosing device through a pipeline, and the fourth grid reaction zone is connected to the alkali dosing device through a pipeline. The device is connected, an online pH meter is arranged in the reaction zone, the fifth reaction zone is connected to the PAM dosing device through a pipeline, and stirring devices are arranged in all five reaction zones; the final sedimentation tank is a vertical flow sedimentation tank, a guide tube is arranged in the center, and overflow weirs are arranged around; the primary sedimentation tank, the secondary sedimentation tank, and the final sedimentation tank are all provided with sludge pumps, which are connected to the sludge thickening tank through a pipeline; one end of the sludge screw pump is connected to the sludge thickening tank through a pipeline, and the section of the pipeline is also connected to the sludge flocculation dosing device through a dosing pipeline, and the other end is connected to the sludge dewatering machine; the sludge thickening tank is connected to the sludge pipeline used to connect the grit tank, the air flotation machine, the primary sedimentation tank, the secondary sedimentation tank, and the final sedimentation tank, and the upper wastewater is connected to the aeration regulating tank through a return pipe.

2. A leather processing wastewater treatment system according to claim 1, characterized in that: The PAC dosing device, acid dosing device, ferrous sulfate dosing device, hydrogen peroxide dosing device and sludge flocculation dosing device are single-barrel two-pump skid-mounted, and the alkali dosing device and PAM dosing device are single-barrel three-pump skid-mounted. Agitators are installed on the tops of the barrels of the PAC dosing device, ferrous sulfate dosing device, alkali dosing device, PAM dosing device and sludge flocculation dosing device.

3. A leather processing wastewater treatment system according to claim 1, characterized in that: The primary O pool and the secondary O pool are respectively provided with mixed liquid reflux pumps, the primary O pool mixed liquid reflux pump is connected to the primary A pool through a pipeline, and the secondary O pool mixed liquid reflux pump is connected to the secondary A pool through a pipeline.

4. A leather processing wastewater treatment system according to claim 1, characterized in that: The primary sedimentation tank sludge pump is connected to the primary A tank and the primary O tank through pipelines, and the secondary sedimentation tank sludge pump is connected to the secondary A tank and the secondary O tank through pipelines.

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