Device and method for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge.

Abstract

An apparatus and method for reducing the COD and conductivity of ammonia-containing wastewater using concentrated sludge includes a thickening tank, a sludge dewatering equipment feed pump, sludge dewatering equipment, and a cationic polyacrylamide flocculant dosing pump. It also includes a coking ammonia-containing wastewater pipeline, a concentrated sludge pipeline, a filtrate pipeline, and a reagent dosing pipeline. The coking ammonia-containing wastewater pipeline introduces the wastewater into the central cylinder of the thickening tank. The two ends of the concentrated sludge pipeline are connected to the coking ammonia-containing wastewater pipeline and the outlet pipeline of the sludge dewatering equipment feed pump, respectively. The two ends of the filtrate pipeline are connected to the coking ammonia-containing wastewater pipeline and the sludge dewatering equipment, respectively. The two ends of the reagent dosing pipeline are connected to the coking ammonia-containing wastewater pipeline and the outlet pipeline of the cationic polyacrylamide flocculant dosing pump, respectively. This invention serves as a further pretreatment step for coking ammonia-containing wastewater after gravity oil removal and air flotation oil removal, aiming to improve the biodegradability of the wastewater, reduce the organic load of the biochemical treatment, and thus improve the system's treatment efficiency.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to an apparatus and method for reducing the COD and conductivity of ammonia-containing wastewater using concentrated sludge. Background Technology

[0002] In coking wastewater treatment processes, after the biochemical effluent containing flocculants such as water purification agents and polyferric sulfate settles in a coagulation sedimentation tank, the settled sludge is typically discharged into a thickening tank as physicochemical sludge. The thickening tank sludge, as the final product, is usually pumped into centrifugal dewatering machines, plate and frame filter presses, or belt drum filter presses for mud-water separation, and then treated as solid waste. However, due to its large specific surface area and active components, the thickened sludge still possesses significant adsorption and degradation capabilities. Especially when combined with the filtrate from centrifugal dewatering machines or plate and frame filter presses, it can be used for further pretreatment of coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal, achieving the goal of treating waste with waste. Currently, there is no research or application in this area. Summary of the Invention

[0003] The purpose of this invention is to provide a device and method for reducing the COD and conductivity of ammonia-containing wastewater using concentrated sludge. This can be used as a further pretreatment step for coking ammonia-containing wastewater after gravity oil removal and air flotation oil removal, thereby improving the biodegradability of the wastewater, reducing the organic load of the biochemical treatment, and thus improving the system treatment effect. It is a waste-to-waste treatment method.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A device for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge includes a thickening tank, a sludge dewatering equipment feed pump, sludge dewatering equipment, and a cationic polyacrylamide flocculant dosing pump. The thickening tank is connected to the sludge dewatering equipment feed pump and the sludge dewatering equipment via a sludge discharge pipeline. The outlet pipeline of the cationic polyacrylamide flocculant dosing pump is connected to the sludge dewatering equipment to add cationic polyacrylamide flocculant to the sludge dewatering equipment. The device also includes a coking ammonia-containing wastewater pipeline, a concentrated sludge pipeline, a filtrate pipeline, and a reagent dosing pipeline. The coking ammonia stripping wastewater pipeline introduces the ammonia stripping wastewater into the central cylinder of the thickening tank. The two ends of the thickened sludge pipeline are respectively connected to the coking ammonia stripping wastewater pipeline and the outlet pipeline of the sludge dewatering equipment feed pump. The two ends of the filtrate pipeline are respectively connected to the coking ammonia stripping wastewater pipeline and the sludge dewatering equipment. The two ends of the reagent dosing pipeline are respectively connected to the coking ammonia stripping wastewater pipeline and the outlet pipeline of the cationic polyacrylamide flocculant dosing pump. Valves E, F, and H are respectively installed on the thickened sludge pipeline, the filtrate pipeline, and the reagent dosing pipeline.

[0006] It also includes a regulating and equalizing tank and a wastewater lifting well. The overflow weir of the thickening tank is connected to the wastewater lifting well through an outlet pipe, and the wastewater lifting well is connected to the regulating and equalizing tank through a pipe.

[0007] The coking ammonia stripping wastewater enters the central cylinder of the thickener by passing through a 90° bend at the top of the central cylinder, with the water outlet of the bend perpendicular to the bottom of the thickener.

[0008] An observation hole is provided at the elbow, and a valve or observation window is installed in the observation hole.

[0009] Valve A is installed on the coking ammonia stripping wastewater pipeline. The connection point between the concentrated sludge pipeline, the filtrate pipeline, the reagent dosing pipeline and the coking ammonia stripping wastewater pipeline is between valve A and the thickening tank.

[0010] The thickening tank is a radial flow thickening tank.

[0011] Methods for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge include:

[0012] 1) The coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is introduced into the central cylinder of the thickener through the coking ammonia stripping wastewater pipeline;

[0013] 2) During operation, open valves A, E, and F to keep the sludge dewatering equipment feed pump and sludge dewatering equipment running, so that the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is mixed with the concentrated sludge and the filtrate of the dewatering equipment in the coking ammonia stripping wastewater pipeline and then enters the central cylinder of the thickening tank.

[0014] 3) When the sludge dewatering equipment is not running, close valve F, open valve H, and start the cationic polyacrylamide flocculant dosing pump so that the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is mixed with the concentrated sludge and cationic polyacrylamide flocculant in the coking ammonia stripping wastewater pipeline and then enters the central cylinder of the thickening tank.

[0015] 4) The overflow effluent from the thickening tank is piped to the wastewater lifting well, and the wastewater in the wastewater lifting well is pumped to the equalization tank.

[0016] The volume ratio of coking ammonia stripping wastewater to concentrated sludge in step 2) above is (10-14):1.

[0017] In step 2) above, the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal has a residence time of more than 4 hours in the thickening tank, and the surface load of the thickening tank is less than 1.1 cubic meters per square meter.

[0018] In step 3) above, the ratio of coking ammonia stripping wastewater: concentrated sludge: cationic polyacrylamide flocculant is (100-140):10:1. The above ratio is a volume ratio to ensure the removal effect of COD and conductivity of coking ammonia stripping wastewater by the sludge in the thickening tank.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1) This invention utilizes sludge from a thickening tank to treat coking ammonia stripping wastewater, reducing the COD and conductivity of the wastewater. It can reduce the COD of the ammonia stripping wastewater by about 30% and the conductivity by about 10%, which is a novel treatment method that uses waste to treat waste.

[0021] 2) The cationic polyacrylamide flocculant added to the ammonia-steaming wastewater in this invention is the centrifugal dewatering liquid, which further utilizes the effective components of the remaining cationic polyacrylamide in the centrifugal dewatering liquid, which is a secondary utilization of the waste liquid; when the centrifugal dewatering machine is not in use, a small amount of cationic polyacrylamide solution can be used to replace the centrifugal dewatering liquid through valve switching to achieve the removal effect of COD and conductivity of coking ammonia-steaming wastewater, thereby ensuring the continuous operation of this treatment method.

[0022] 3) In this invention, coking ammonia stripping wastewater, concentrated sludge, and flocculant solution are mixed through pipelines and then enter the thickening tank, eliminating the mixing and stirring reaction process and saving investment.

[0023] 4) The sludge thickening method of this invention adopts the method of sludge self-circulation in the pool, which not only ensures the stability of sludge concentration, but also facilitates control and operation, and has good practicality in industrial production. Attached Figure Description

[0024] Figure 1 This is a simplified process diagram of the present invention.

[0025] In the diagram: 1-Valve A, 2-Valve H, 3-Valve F, 4-Valve E, 5-Concentrated sludge pipeline, 6-Filtrate pipeline, 7-Reagent dosing pipeline, 8-Equalization tank, 9-Wastewater lifting well, 10-Concentration tank, 11-Sludge dewatering equipment feed pump, 12-Sludge dewatering equipment, 13-Catonic polyacrylamide flocculant dosing pump, 14-Coking ammonia stripping wastewater pipeline. Detailed Implementation

[0026] The embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0027] like Figure 1As shown, the device for reducing the COD and conductivity of ammonia-containing wastewater using concentrated sludge includes a thickening tank 10, a sludge dewatering equipment feed pump 11, a sludge dewatering equipment 12, and a cationic polyacrylamide flocculant dosing pump 13. The thickening tank 10 is connected to the sludge dewatering equipment feed pump 11 and the sludge dewatering equipment 12 via a sludge discharge pipe. The outlet pipe of the cationic polyacrylamide flocculant dosing pump 13 is connected to the sludge dewatering equipment 12, and cationic polyacrylamide flocculant is added to the sludge dewatering equipment 12. The device also includes a coking ammonia-containing wastewater pipe 14, a concentrated sludge pipe 5, a filtrate pipe 6, and a reagent dosing system. Pipeline 7 and coking ammonia stripping wastewater pipeline 14 introduce ammonia stripping wastewater into the central cylinder of thickening tank 10. The two ends of thickened sludge pipeline 5 are respectively connected to the outlet pipeline of coking ammonia stripping wastewater pipeline 14 and sludge dewatering equipment feed pump 11. The two ends of filtrate pipeline 6 are respectively connected to coking ammonia stripping wastewater pipeline 14 and sludge dewatering equipment 12. The two ends of reagent dosing pipeline 7 are respectively connected to coking ammonia stripping wastewater pipeline 14 and cationic polyacrylamide flocculant dosing pump 13. Valves E4, F3 and H2 are respectively installed on thickened sludge pipeline 5, filtrate pipeline 6 and reagent dosing pipeline 7.

[0028] It also includes a regulating and equalizing tank 8, a wastewater lifting well 9, and the overflow weir of the thickening tank 10 is connected to the wastewater lifting well 9 through an outlet pipe. The wastewater lifting well 9 is connected to the regulating and equalizing tank 8 through a pipe.

[0029] The coking ammonia stripping wastewater pipeline 14 enters the central cylinder of the thickener 10 by passing through a 90° bend at the top of the central cylinder of the thickener 10. The water outlet of the bend is perpendicular to the bottom of the thickener 10 to prevent the ammonia stripping wastewater from splashing into the thickener.

[0030] An observation hole B is provided at the bend, and a flap valve or observation window is installed in the observation hole B.

[0031] Valve A1 is installed on the coking ammonia stripping wastewater pipeline. The connection point between the thickened sludge pipeline 5, the filtrate pipeline 6, the reagent dosing pipeline 7 and the coking ammonia stripping wastewater pipeline 14 is between valve A1 and the thickening tank 10.

[0032] Methods for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge include:

[0033] 1) The coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is introduced into the central cylinder of the thickener 10 through the coking ammonia stripping wastewater pipeline 14.

[0034] 2) During operation, open valves A1, E3, and F4 to keep the sludge dewatering equipment feed pump 11 and sludge dewatering equipment 12 running, so that the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is mixed with the concentrated sludge and the filtrate of the dewatering equipment in the coking ammonia stripping wastewater pipeline 14 and then enters the central cylinder of the thickening tank 10.

[0035] The volume ratio of coking ammonia stripping wastewater to concentrated sludge is (10-14):1.

[0036] The coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal has a residence time of more than 4 hours in the thickener 10, and the surface loading of the thickener 10 is less than 1.1 cubic meters per square meter.

[0037] 3) When the sludge dewatering equipment 12 is not running, close valve F3, open valve H2, and start the cationic polyacrylamide flocculant dosing pump 13. This allows the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal to be mixed with concentrated sludge and cationic polyacrylamide flocculant in the coking ammonia stripping wastewater pipeline 14 before entering the central cylinder of the thickening tank 10. The ratio of coking ammonia stripping wastewater to concentrated sludge to cationic polyacrylamide flocculant is (100-140):10:1, which is a volume ratio, to ensure the removal effect of sludge in the thickening tank 10 on COD and conductivity of coking ammonia stripping wastewater.

[0038] 4) The overflow weir of the thickening tank 10 is led to the wastewater lifting well 9 through a pipeline, and the wastewater in the wastewater lifting well 9 is sent to the equalization tank 8 by a pump.

[0039] Example: Example 10 uses a radial flow thickener.

[0040] 1. The coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is introduced into the central cylinder of the radial flow thickener through a DN150mm coking ammonia stripping wastewater pipe 14. The coking ammonia stripping wastewater pipe 14 enters the central cylinder from the top of the central cylinder through a 90° bend. The water outlet direction of the bend is perpendicular to the bottom of the radial flow thickener. A valve A1 is installed at a distance of 3.5 meters from the central cylinder of the coking ammonia stripping wastewater pipe 14 for control.

[0041] 2. At a distance of 3 meters from the central cylinder on the coking ammonia stripping wastewater pipeline 14, a DN50mm thickened sludge pipeline 5 is connected by welding. The other end of the thickened sludge pipeline 5 is connected to the outlet end of the sludge dewatering equipment feed pump 11, and a valve E4 is installed for control.

[0042] 3. At a distance of 2.5 meters from the central cylinder on the coking ammonia stripping wastewater pipeline 14, a DN100mm filtrate pipeline 6 is connected by welding, and a valve F3 is installed on the filtrate pipeline 6 for control.

[0043] 4. At a distance of 2 meters from the central cylinder on the coking ammonia stripping wastewater pipeline 14, a DN20mm reagent dosing pipeline 7 is connected by welding. The other end of the reagent dosing pipeline 7 is connected to the outlet pipe of the cationic polyacrylamide flocculant dosing pump 13 in a bypass manner. A valve H2 is installed on the reagent dosing pipeline 7 for control.

[0044] 5. A sampling observation hole B is installed next to the outlet elbow of the coking ammonia stripping wastewater pipeline 14, and a movable flap valve is installed on the observation hole B. The flap valve is normally in the closed state.

[0045] 6. During operation, open valves A1, E4, and F3 to keep the sludge dewatering equipment feed pump 11 and sludge dewatering equipment 12 running. This allows the coking ammonia stripping wastewater, concentrated sludge, and dewatering equipment filtrate, after gravity oil removal and air flotation oil removal, to be mixed in the coking ammonia stripping wastewater pipeline 14 before entering the central cylinder of the radial flow thickener. The ratio of coking ammonia stripping wastewater to concentrated sludge is 10:1. The residence time of the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal in the radial flow thickener is greater than 4 hours, and the surface load of the radial flow thickener is less than 1.1 cubic meters per square meter.

[0046] 7. When the sludge dewatering equipment 12 is not running, close valve F3, open valve H2, and start the cationic polyacrylamide flocculant dosing pump 13. This allows the coking ammonia stripping wastewater, concentrated sludge, and cationic polyacrylamide flocculant, which have undergone gravity oil removal and air flotation oil removal, to be mixed in the coking ammonia stripping wastewater pipeline 14 and then enter the central cylinder of the radial flow thickening tank. The ratio of coking ammonia stripping wastewater: concentrated sludge: cationic polyacrylamide flocculant is 100:10:1 to ensure the removal effect of COD and conductivity of the coking ammonia stripping wastewater by the sludge in the thickening tank.

[0047] 8. The overflow weir of the radial flow thickener is led through a pipeline to the wastewater lifting well 9, and the wastewater in the wastewater lifting well 9 is sent to the equalization tank 8 by a pump.

[0048] The influent parameters of the coking ammonia stripping wastewater pipeline 14 in the example are shown in Table 1; the effluent parameters of the treated equalization tank 8 in the example are shown in Table 2.

[0049] Table 1 Data on Coking Ammonia Removal Wastewater Pipelines

[0050]

[0051] Table 2. Effluent Indicators from the Equalization Tank

[0052]

[0053]

[0054] This invention allows for the selection of the optimal construction scheme based on the on-site process route and pipeline layout. It is easy to construct and operate, and is especially beneficial for projects with downstream greywater deep treatment processes, as the reduction in conductivity is highly beneficial for the protection of the membrane system.

Claims

1. A method for reducing the COD and conductivity of ammonia-containing wastewater using concentrated sludge, comprising a device for reducing the COD and conductivity of ammonia-containing wastewater using concentrated sludge, including a thickening tank, a sludge dewatering equipment feed pump, a sludge dewatering equipment, and a cationic polyacrylamide flocculant dosing pump. The thickening tank is connected to the sludge dewatering equipment feed pump and the sludge dewatering equipment via a sludge discharge pipe. The outlet pipe of the cationic polyacrylamide flocculant dosing pump is connected to the sludge dewatering equipment, and cationic polyacrylamide flocculant is added to the sludge dewatering equipment. The method is characterized in that... It also includes a coking ammonia stripping wastewater pipeline, a concentrated sludge pipeline, a filtrate pipeline, and a reagent dosing pipeline. The coking ammonia stripping wastewater pipeline introduces the ammonia stripping wastewater into the central cylinder of the thickening tank. The two ends of the concentrated sludge pipeline are respectively connected to the coking ammonia stripping wastewater pipeline and the outlet pipeline of the sludge dewatering equipment feed pump. The two ends of the filtrate pipeline are respectively connected to the coking ammonia stripping wastewater pipeline and the sludge dewatering equipment. The two ends of the reagent dosing pipeline are respectively connected to the coking ammonia stripping wastewater pipeline and the outlet pipeline of the cationic polyacrylamide flocculant dosing pump. Valves E, F, and H are respectively installed on the concentrated sludge pipeline, the filtrate pipeline, and the reagent dosing pipeline. It also includes a regulating and equalizing tank and a wastewater lifting well. The overflow weir of the thickening tank is connected to the wastewater lifting well through an outlet pipe, and the wastewater lifting well is connected to the regulating and equalizing tank through a pipe. Specific methods include: 1) The coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is introduced into the central cylinder of the thickener through the coking ammonia stripping wastewater pipeline; 2) During operation, open valves A, E, and F to keep the sludge dewatering equipment feed pump and sludge dewatering equipment running, so that the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is mixed with the concentrated sludge and the filtrate of the dewatering equipment in the coking ammonia stripping wastewater pipeline and then enters the central cylinder of the thickening tank. 3) When the sludge dewatering equipment is not running, close valve F, open valve H, and start the cationic polyacrylamide flocculant dosing pump so that the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal is mixed with the concentrated sludge and cationic polyacrylamide flocculant in the coking ammonia stripping wastewater pipeline and then enters the central cylinder of the thickening tank. 4) The overflow effluent from the thickening tank is piped to the wastewater lifting well, and the wastewater in the wastewater lifting well is pumped to the equalization tank.

2. The method for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge according to claim 1, characterized in that, The coking ammonia stripping wastewater enters the central cylinder of the thickener by passing through a 90° bend at the top of the central cylinder, with the water outlet of the bend perpendicular to the bottom of the thickener.

3. The method for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge according to claim 2, characterized in that, An observation hole is provided at the elbow, and a valve or observation window is installed in the observation hole.

4. The method for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge according to claim 1, characterized in that, Valve A is installed on the coking ammonia stripping wastewater pipeline. The connection point between the concentrated sludge pipeline, the filtrate pipeline, the reagent dosing pipeline and the coking ammonia stripping wastewater pipeline is between valve A and the thickening tank.

5. The method for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge according to claim 1, characterized in that, The thickening tank is a radial flow thickening tank.

6. The method for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge according to claim 1, characterized in that, The volume ratio of coking ammonia stripping wastewater to concentrated sludge in step 2) above is (10-14):

1.

7. The method for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge according to claim 1, characterized in that, In step 2) above, the coking ammonia stripping wastewater after gravity oil removal and air flotation oil removal has a residence time of more than 4 hours in the thickening tank.

8. The method for reducing COD and conductivity of ammonia-containing wastewater using concentrated sludge according to claim 1, characterized in that, In step 3) above, the ratio of coking ammonia stripping wastewater to concentrated sludge to cationic polyacrylamide flocculant is (100-140):10:1, and the above ratio is a volume ratio.

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