Coking wastewater treatment system

Abstract

The invention discloses a coking wastewater treatment system. The coking wastewater treatment system comprises a biochemical pretreatment system, a biochemical treatment system, a deep pretreatment system, a deep treatment system, a concentrated water treatment system, a matched dosing system and a sludge treatment system which are connected in sequence, the coking wastewater is used for blast furnace smelting slag flushing after being treated by the coking wastewater treatment system. According to the coking wastewater treatment system, a two-stage A / O process is adopted, meanwhile, an ozone advanced oxidation process is used for oxidizing part of pollutants and decolorizing a water body, the removal effect on COD, ammonia nitrogen, cyanide and other pollutants and chromaticity is enhanced, after ozone is decomposed, a decomposition product is oxygen, secondary pollution is not caused, and no sludge is generated. The coking wastewater treated by the treatment system disclosed by the invention meets the water standard for blast furnace slag flushing.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a coking wastewater treatment system. Background Art

[0002] Coking wastewater mainly comes from the primary cooling of coke oven gas, production water used in the coking production process, and steam condensation wastewater. It is a toxic and difficult to degrade organic wastewater.

[0003] The existing common biochemical treatment technologies for coking wastewater mainly include A / O process and its variants and SBR process. However, faced with increasingly higher treatment requirements and trends, this technology has certain limitations in the removal rate of major pollutant factors such as high organic matter, ammonia nitrogen, cyanide, etc. contained in coking wastewater. Summary of the invention

[0004] The object of the present invention is to provide a coking wastewater treatment system.

[0005] The object of the present invention is achieved in this way: a coking wastewater treatment system comprises a biochemical pretreatment system, a biochemical treatment system, a deep pretreatment system, a deep treatment system, a concentrated water treatment system and a matching dosing system and a sludge treatment system connected in sequence; the coking wastewater is used for blast furnace smelting slag flushing after being treated by the coking wastewater treatment system; The biochemical pretreatment system includes an accident pool, a grease trap, a regulating pool, a water collection pool, and a water distribution pool connected in sequence; The biochemical treatment system comprises a primary anoxic tank, a primary aerobic tank, a primary sedimentation tank, a primary biochemical effluent tank, a secondary anoxic tank, a secondary aerobic tank, a secondary sedimentation tank, and a buffer tank which are connected in sequence; The deep pretreatment system includes a hardness removal high-density tank, a high-density water outlet tank, a shallow sand filter, an ozone advanced oxidation device, an aerated biological filter, and an intermediate water tank which are connected in sequence; The deep treatment system includes a combined water pool, a multi-media filter, an ultrafiltration system, and a reverse osmosis system that are connected in sequence; The concentrated water treatment system comprises a Fenton AOP unit, an inclined plate sedimentation tank and a Fenton effluent tank which are connected in sequence.

[0006] The beneficial effects of the present invention are as follows: the coking wastewater treatment system of the present invention adopts a two-stage A / O process, and simultaneously utilizes an ozone advanced oxidation process to oxidize some pollutants and decolorize the water body, thereby enhancing the removal effect of pollutants such as COD, ammonia nitrogen, cyanide, and chromaticity, and after ozone decomposition, the decomposition product is oxygen, which does not cause secondary pollution and does not generate sludge. The coking wastewater treated by the treatment system of the present invention meets the standard for water used for blast furnace slag flushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1It is a process flow chart of the coking wastewater treatment system of the present invention; Figure 2 This is a process flow chart of the biochemical treatment system of the present invention; Figure 3 This is a process flow chart of the deep pretreatment system of the present invention. DETAILED DESCRIPTION

[0008] The present invention is further described below in conjunction with the embodiments and drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0009] The present invention provides a coking wastewater treatment system, such as Figure 1 As shown, it includes a biochemical pretreatment system, a biochemical treatment system, a deep pretreatment system, a deep treatment system, a concentrated water treatment system, and a matching dosing system and sludge treatment system connected in sequence; the coking wastewater is treated by the coking wastewater treatment system and then used for blast furnace smelting slag flushing; The biochemical pretreatment system includes an accident pool, a grease trap, a regulating pool, a water collection pool, and a water distribution pool which are connected in sequence; its task is to remove heavy oil and light oil in the coking wastewater, regulate the water volume, and make the water quality uniform.

[0010] The biochemical treatment system ( Figure 2 ) includes a first-level anoxic tank, a first-level aerobic tank, a first-level sedimentation tank, a first-level biochemical effluent tank, a second-level anoxic tank, a second-level aerobic tank, a second-level sedimentation tank, and a buffer tank ( Figure 2 ); The main task of the biochemical treatment system is to remove organic pollutants, ammonia nitrogen, cyanide, etc. in wastewater.

[0011] The deep pretreatment system includes a hardness removal high-density tank, a high-density water outlet tank, a shallow sand filter, an ozone advanced oxidation device, an aerated biological filter, an intermediate water tank ( Figure 3 ); The deep treatment system comprises a combined water pool, a multi-media filter, an ultrafiltration system and a reverse osmosis system which are connected in sequence; the media in the multi-media filter are quartz sand and anthracite of various particle sizes.

[0012] The concentrate treatment system comprises a Fenton AOP unit, an inclined plate sedimentation tank and a concentrate high-density Fenton outlet tank which are connected in sequence.

[0013] In the biochemical treatment system, a first-level anoxic pool is equipped with a box-type composite filler designed in an upward flow form. A perforated water distribution pipe is provided in the pool to evenly mix the wastewater with the nitrification liquid and the return sludge. A sludge discharge pipe is provided at the bottom of the pool.

[0014] In the biochemical treatment system, the primary aerobic pool is designed as a plug-flow gallery pool, and a microporous aerator and a submersible mixer are arranged at the bottom.

[0015] In the biochemical treatment system, the mixed liquor of the primary aerobic tank flows by gravity into the primary sedimentation tank for mud-water separation, the sludge flows back to the primary anoxic tank and the primary aerobic tank respectively, a part of the clean water flows back to the primary anoxic tank, and the rest flows by gravity into the secondary anoxic tank through the primary biochemical effluent tank.

[0016] A defoaming water pipe is installed on the top of the aerobic pool to prevent foam from overflowing due to aeration.

[0017] In the deep pretreatment system, lime and sodium carbonate are added to the hardness removal high-density tank to remove hardness, and aluminum salt is added to perform preliminary removal of fluoride ions.

[0018] The concentrated water obtained by reverse osmosis treatment of wastewater in the deep treatment system is first treated with cyanide before entering the concentrated water treatment system.

[0019] The method for treating cyanide in concentrated water is to adjust the pH of concentrated water obtained by reverse osmosis treatment of coking wastewater to be treated to 4.0 or below, add excess ferrous sulfate solution while stirring at a speed of 72 rpm to react for at least 1.0 hour, and after sufficient reaction, remove the cyanide precipitate to obtain concentrated water with cyanide removed.

[0020] The sludge treatment system comprises a sludge thickening tank (system sludge collection and storage), a sludge homogenization tank (sludge property adjustment), a sludge dewatering machine, and a sludge dewatering room which are connected in sequence; part of the sludge that is not returned in the primary sedimentation tank and the secondary sedimentation tank in the deep pretreatment system and the sludge in the Fenton sedimentation tank in the concentrated water treatment system are discharged into the sludge thickening tank.

[0021] The coking wastewater treatment system also includes a biochemical deodorization system, which is arranged in the biochemical treatment system area to collect waste gas from various process structures and sludge concentration tanks in the entire biochemical treatment system. The biochemical deodorization system includes a matching air collection hood, air duct and biological deodorization device.

[0022] The dosing system pumps the chemicals in the medicine pool to various chemical use points through a dosing pump and a dosing pipeline, including a polyacrylamide dosing device, a lime dosing device, a sodium carbonate dosing device, a dilute sulfuric acid dosing device, a hydrochloric acid dosing device, a sodium hydroxide dosing device, a sodium hypochlorite dosing device, and a ferrous sulfate dosing device.

[0023] Example 1 The wastewater treatment capacity of the coking wastewater treatment system in this embodiment is 120m 3 / h design, coking wastewater inflow 80m 3 / h, cooling cycle sewage inlet 40m 3 / h, the quality of the wastewater to be treated is shown in Table 1. Figure 1 The coking wastewater treatment system shown treats wastewater.

[0024] Table 1 Water quality of coking wastewater to be treated in Example 1 The sewage after biochemical pretreatment is lifted by a water pump and passed through a water distributor into the primary anoxic tank. The primary anoxic tank is equipped with a box-type combined filler and is designed in an upward flow form. A perforated water distribution pipe is provided in the tank to evenly mix the wastewater with the nitrification liquid and the return sludge (intermittently). To prevent the sludge from settling and decaying, a bottom mud discharge pipe is provided. In the anoxic tank, the nitrate nitrogen in the sewage is reduced to nitrogen gas and escapes from the wastewater by the denitrification reaction of facultative anaerobic bacteria, thereby achieving the purpose of removing total nitrogen. The effluent of the primary anoxic tank flows by gravity into the primary aerobic tank. A microporous aerator and a submersible mixer are provided at the bottom of the tank, which is designed in a plug-flow gallery-type tank shape. In the primary aerobic tank, phenol, cyanide and other harmful substances in the wastewater are removed by the degradation action of aerobic microorganisms, and the ammonia nitrogen in the wastewater is oxidized to nitrate nitrogen by nitrification reaction.

[0025] The mixed liquid of the primary aerobic pool flows by gravity into the primary sedimentation tank for mud and water separation. The sludge flows back to the primary anoxic pool and the aerobic pool respectively. A part of the clean water flows back to the primary anoxic pool, and the rest flows by gravity into the secondary anoxic pool through the primary biochemical effluent pool. Glucose is added to the secondary anoxic pool to supplement the carbon source required for denitrification, so that the remaining nitrate nitrogen in the sewage is denitrified again, reduced to nitrogen gas and escapes from the wastewater, achieving the purpose of further denitrification. The effluent flows by gravity into the secondary aerobic pool to further degrade the remaining degradable organic matter in the sewage. The effluent of the secondary aerobic pool flows by gravity to the secondary sedimentation tank for mud and water separation. The sludge flows back to the secondary anoxic pool, and the supernatant effluent flows by gravity to the buffer pool, mixed with the external circulating sewage, and then lifted by a water pump and enters the deep pretreatment system. The remaining sludge is discharged into the sludge concentration pool. The top of the primary aerobic pool and the secondary aerobic pool is equipped with a defoaming water pipe to prevent the overflow of foam caused by aeration.

[0026] The effluent from the buffer tank enters the high-efficiency hardness removal sedimentation tank system, and lime and sodium carbonate are added to the wastewater to remove the hardness. The dosage of each agent can be adjusted according to the specific water quality. At the same time, aluminum salt is added to preliminarily remove fluoride ions. The effluent from the sedimentation tank enters the subsequent shallow sand filter after pH adjustment by adding acid, which is used to remove suspended matter that is not removed during the sedimentation process, and can also deal with the sludge overturning phenomenon that may occur in the high-density pool. After passing through the shallow sand filter, the wastewater enters the ozone oxidation unit, and the highly active hydroxyl free radicals generated by ozone are used to attack and react with macromolecular organic matter, thereby destroying the organic molecular structure to achieve the purpose of oxidative removal of organic matter, and achieving efficient oxidation treatment of organic pollutants in the wastewater, and achieving efficient and sludge-free removal of organic pollutants. After the wastewater is degraded by ozone advanced oxidation, the organic matter in the wastewater that was originally non-biodegradable is opened and broken, thereby becoming a biodegradable substance. When the wastewater flows through the BAF biological filter, the wastewater is biochemically treated by the biological oxidation and degradation of the highly active biofilm on the surface of the filter material and the biological flocs between the filter materials. Finally, it is lifted to the deep treatment system through the intermediate water tank.

[0027] The deep treatment system adopts the "ultrafiltration + primary reverse osmosis" treatment process. The wastewater is first filtered through a multi-media filter to remove some suspended matter, and then enters the "ultrafiltration + primary reverse osmosis" system. The produced water after reverse osmosis treatment enters the reuse water pool for reuse. The concentrated water is treated to remove cyanide: the concentrated water to be treated is discharged into the concentrated water treatment pool, the pH is adjusted to 4.0, the treatment stirring device is turned on, and the prepared ferrous sulfate solution (excessive) is added. After sufficient reaction, the cyanide is precipitated, and the supernatant is discharged into the concentrated water treatment system (the concentrated water treatment system includes the Fenton AOP unit, the inclined plate sedimentation tank and the Fenton effluent tank). The Fenton process is used to degrade the COD and other organic matter concentrated by the deep treatment membrane, and then sent to the blast furnace for slag flushing treatment.

[0028] According to the test, after ozone advanced oxidation, the chromaticity of the wastewater was reduced to 1 / 4 of that before ozone decolorization (the chromaticity dropped from 100 to 25), which greatly improved the sensory effect of the sewage water quality; the water quality of the recycled water and slag flushing water is shown in Table 2 and Table 3: Table 2 Water quality of recycled water obtained from Example 1 Table 3 Water quality of slag flushing water obtained in Example 1 It can be seen from Table 2-3 that the water quality of coking wastewater is significantly improved after being treated by the treatment system of the present invention. At the same time, the treated concentrated water meets the relevant requirements of the "Coking Chemical Industry Pollutant Emission Standard" GB16171-2012 and can be used for blast furnace slag flushing.

Claims

1. A coking wastewater treatment system, characterized in that: It includes a biochemical pretreatment system, a biochemical treatment system, a deep pretreatment system, a deep treatment system, a concentrated water treatment system, and a matching dosing system and sludge treatment system connected in sequence; After being treated by the coking wastewater treatment system, the coking wastewater is used for slag flushing in blast furnace smelting; The biochemical pretreatment system includes an accident pool, a grease trap, a regulating pool, a water collection pool, and a water distribution pool connected in sequence; The biochemical treatment system comprises a primary anoxic tank, a primary aerobic tank, a primary sedimentation tank, a primary biochemical effluent tank, a secondary anoxic tank, a secondary aerobic tank, a secondary sedimentation tank, and a buffer tank which are connected in sequence; The deep pretreatment system includes a hardness removal high-density tank, a high-density water outlet tank, a shallow sand filter, an ozone advanced oxidation device, an aerated biological filter, and an intermediate water tank which are connected in sequence; The deep treatment system includes a combined water pool, a multi-media filter, an ultrafiltration system, and a reverse osmosis system that are connected in sequence; The concentrated water treatment system comprises a Fenton AOP unit, an inclined plate sedimentation tank and a Fenton effluent tank which are connected in sequence.

2. The coking wastewater treatment system according to claim 1, characterized in that: In the biochemical treatment system, a first-level anoxic pool is equipped with a box-type composite filler designed in an upward flow form. A perforated water distribution pipe is provided in the pool to evenly mix the wastewater with the nitrification liquid and the return sludge. A sludge discharge pipe is provided at the bottom of the pool.

3. The coking wastewater treatment system according to claim 1, characterized in that: In the biochemical treatment system, the primary aerobic pool is designed as a plug-flow gallery pool, and a microporous aerator and a submersible mixer are arranged at the bottom.

4. The coking wastewater treatment system according to claim 1, characterized in that: In the biochemical treatment system, the mixed liquid of the first aerobic tank flows by gravity into the first sedimentation tank for mud and water separation, the sludge is returned to the first anoxic tank and the first aerobic tank respectively, a part of the clean water is returned to the first anoxic tank, and the rest flows by gravity into the second anoxic tank through the first biochemical effluent tank; A defoaming water pipe is installed on the top of the aerobic pool to prevent foam from overflowing due to aeration.

5. The coking wastewater treatment system according to claim 1, characterized in that: In the deep pretreatment system, lime and sodium carbonate are added to the hardness removal high-density tank to remove hardness, and aluminum salt is added to perform preliminary removal of fluoride ions.

6. The coking wastewater treatment system according to claim 1, characterized in that: The concentrated brine obtained by reverse osmosis treatment of wastewater in the deep treatment system is first treated with cyanide before entering the concentrated water treatment system.

7. The coking wastewater treatment system according to claim 6, characterized in that: The method for treating cyanide in concentrated water is to adjust the pH of concentrated water obtained by reverse osmosis treatment of coking wastewater to be treated to 4.0 or below, add excess ferrous sulfate solution while stirring at a speed of 72RPM to react for at least 1.0 hour, and after sufficient reaction, remove the cyanide precipitate to obtain concentrated water with cyanide removed.

8. The coking wastewater treatment system according to claim 1, characterized in that: The sludge treatment system comprises a sludge thickening tank, a sludge homogenizing tank, a sludge dewatering machine and a sludge dewatering room which are connected in sequence; part of the sludge not returned in the primary sedimentation tank and the secondary sedimentation tank in the deep pretreatment system and the sludge in the Fenton sedimentation tank in the concentrated water treatment system are discharged into the sludge thickening tank.

9. The coking wastewater treatment system according to claim 1, characterized in that: The coking wastewater treatment system also includes a biochemical deodorization system for collecting waste gas from various process structures and sludge concentration tanks in the entire biochemical treatment system. The biochemical deodorization system includes a matching gas collection hood, air duct and biological deodorization device.

10. The coking wastewater treatment system according to claim 1, characterized in that: The dosing system pumps the chemicals in the medicine pool to various chemical use points through a dosing pump and a dosing pipeline, including a polyacrylamide dosing device, a lime dosing device, a sodium carbonate dosing device, a dilute sulfuric acid dosing device, a hydrochloric acid dosing device, a sodium hydroxide dosing device, a sodium hypochlorite dosing device, and a ferrous sulfate dosing device.

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