CN115196828A - Stainless steel pickling waste water denitrification processing system - Google Patents
Stainless steel pickling waste water denitrification processing system Download PDFInfo
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- CN115196828A CN115196828A CN202210829208.9A CN202210829208A CN115196828A CN 115196828 A CN115196828 A CN 115196828A CN 202210829208 A CN202210829208 A CN 202210829208A CN 115196828 A CN115196828 A CN 115196828A
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- softening
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- 239000002351 wastewater Substances 0.000 title claims abstract description 70
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 56
- 239000010935 stainless steel Substances 0.000 title claims abstract description 56
- 238000005554 pickling Methods 0.000 title claims abstract description 54
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 74
- 239000007788 liquid Substances 0.000 claims abstract description 45
- 238000006243 chemical reaction Methods 0.000 claims abstract description 40
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 32
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 16
- 238000001556 precipitation Methods 0.000 claims abstract description 16
- 230000001376 precipitating effect Effects 0.000 claims abstract description 10
- 238000007599 discharging Methods 0.000 claims abstract description 4
- 238000004062 sedimentation Methods 0.000 claims description 16
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical group OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 238000005345 coagulation Methods 0.000 claims description 10
- 230000015271 coagulation Effects 0.000 claims description 10
- 239000000701 coagulant Substances 0.000 claims description 8
- 238000005189 flocculation Methods 0.000 claims description 8
- 230000016615 flocculation Effects 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 7
- 229910001385 heavy metal Inorganic materials 0.000 claims description 6
- 150000002500 ions Chemical class 0.000 claims description 6
- 239000010802 sludge Substances 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 229920002401 polyacrylamide Polymers 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 4
- 125000000129 anionic group Chemical group 0.000 claims description 4
- 239000006228 supernatant Substances 0.000 claims description 4
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 3
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 claims description 3
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 3
- 239000008103 glucose Substances 0.000 claims description 3
- 239000001632 sodium acetate Substances 0.000 claims description 3
- 235000017281 sodium acetate Nutrition 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 abstract description 7
- 239000013049 sediment Substances 0.000 abstract 1
- 239000011575 calcium Substances 0.000 description 19
- 238000000034 method Methods 0.000 description 17
- 238000010992 reflux Methods 0.000 description 13
- 230000008569 process Effects 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 239000013043 chemical agent Substances 0.000 description 6
- 239000003814 drug Substances 0.000 description 5
- 238000006386 neutralization reaction Methods 0.000 description 5
- 238000004065 wastewater treatment Methods 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- 239000011737 fluorine Substances 0.000 description 4
- 229910052731 fluorine Inorganic materials 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 244000005700 microbiome Species 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- -1 fluorine ions Chemical class 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 241000894006 Bacteria Species 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- MMDJDBSEMBIJBB-UHFFFAOYSA-N [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] Chemical compound [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] MMDJDBSEMBIJBB-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006115 defluorination reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002198 insoluble material Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/15—N03-N
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/16—Total nitrogen (tkN-N)
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/28—Anaerobic digestion processes
- C02F3/286—Anaerobic digestion processes including two or more steps
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Removal Of Specific Substances (AREA)
Abstract
The invention provides a denitrification treatment system for stainless steel pickling wastewater, which comprises a softening device, a precipitation device, a primary biological denitrification device and a secondary biological denitrification device which are communicated in sequence; wherein the softening device is communicated with the primary biological denitrification device through a return pipeline to receive part of denitrification liquid, and is used for leading Ca in the stainless steel pickling wastewater to be 2+ With in denitrification liquors
A softening reaction takes place to form CaCO 3 Precipitating; sediment bagArranged for removing CaCO in the water from the softening apparatus 3 Precipitating; first-stage biological denitrification device for discharging the precipitation device into water
Reduction to N 2 Removing, wherein part of the denitrification liquid produced by the first-stage biological denitrification device flows back to the softening device through a return pipeline, and the rest part of the denitrification liquid enters the second-stage biological denitrification device; and the secondary biological denitrification device is used for further removing the total nitrogen in the denitrification liquid. The invention solves the problems of high consumption of softening and hardness-removing agents and unstable quality of effluent after biological denitrification treatment.
Description
Technical Field
The invention relates to the technical field of wastewater treatment, in particular to a denitrification treatment system for stainless steel pickling wastewater.
Background
The stainless steel pickling process generates pickling wastewater containing nitric acid, hydrofluoric acid, iron, nickel, chromium and other heavy metal ions, and in engineering, a neutralization and precipitation process is usually adopted to remove the fluorine ions and the heavy metal ions in the wastewater, and a biological denitrification process is usually adopted to remove nitrate nitrogen in the wastewater. The principle of the biological denitrification process is as follows: takes additional methanol or other easily degradable organic matters as an electron donor and uses denitrifying bacteria to remove the organic matters
Reduction to N 2 Removing, the reaction product also comprises
In actual operation, ca (OH) is often excessively added into the wastewater in order to fully form precipitates and remove fluorine ions and heavy metal ions 2 Or CaCl 2 Chemical agents such as the like enable the hardness of the inlet water of the subsequent treatment facility to be higher, and scaling of a water pump, a pipeline and the inner wall of the tank body is easy to cause; especially in the biological denitrification treatment process, due to the generation of the biological denitrification process
Alkalinity, generated
With Ca in the feed water 2+ Reaction to form CaCO as insoluble substance 3 So that the inorganic matter content in the denitrification sludge is increased and the microbial activity is reduced, thereby reducing the denitrification efficiency of the biochemical system. In addition, in the stainless steel pickling wastewater
The concentration is easy to be dischargedThe water quality of the effluent subjected to biological denitrification treatment is unstable due to the large fluctuation.
Introducing high-concentration Ca for solving the problem of wastewater front-end treatment 2+ The improvement method mainly comprises the following steps of setting softening and hardness removal measures before a biological denitrification process: adding Na into the denitrification influent 2 CO 3 Chemical agent, and Ca in wastewater 2+ Formation of CaCO 3 And precipitates, thereby reducing the hardness of the wastewater.
For example, chinese invention patent (with the patent number of CN 201110262418.6) discloses a method for preventing scale formation in the subsequent treatment of stainless steel acid wastewater, carbonate is added into lime neutralization precipitation effluent for softening, and the mass ratio of the addition amount of the carbonate to the calcium content in the wastewater is 1. Although the added medicament can soften and remove hardness to solve the problem of high concentration of Ca 2+ The biological denitrification is influenced, but the method has the main defects that: ca in the precipitated water is neutralized by lime 2+ The concentration is high, and a large amount of chemical agents are required to be added to achieve a good softening and hardness removal effect, so that the cost of wastewater treatment agents is greatly increased.
Disclosure of Invention
The invention aims to provide a denitrification treatment system for stainless steel pickling wastewater, which realizes the purpose of softening and hardness removal of the stainless steel pickling wastewater, solves the problem of high consumption of softening and hardness removal agents and solves the problem of high consumption of the softening and hardness removal agents in the stainless steel pickling wastewater
The concentration fluctuation range is large, and the stable standard of the effluent quality is ensured.
In order to achieve the aim, the invention provides a stainless steel pickling wastewater denitrification treatment system, which comprises a softening device, a precipitation device, a primary biological denitrification device and a secondary biological denitrification device which are communicated in sequence; wherein the content of the first and second substances,
the softening device is communicated with the primary biological denitrification device through a return pipeline to receive partial denitrification liquid produced by the primary biological denitrification device, and the softening device is used for enabling the stainless steel acid washing device to be used for washingCa in wastewater 2+ With respect to the denitrification liquid
A softening reaction takes place to form CaCO 3 Precipitating;
the precipitation device is used for removing CaCO in the water discharged from the softening device 3 Precipitating;
the first-stage biological denitrification device is used for discharging the sedimentation device into water
Reduction to N 2 Removing, wherein part of the denitrification liquid produced by the primary biological denitrification device flows back to the softening device through the return pipeline, and the rest part of the denitrification liquid enters the secondary biological denitrification device;
the secondary biological denitrification device is used for further removing the total nitrogen in the denitrification liquid.
Optionally, the ratio of the flow rate of the denitrification liquid flowing back to the softening device to the flow rate of the denitrification liquid entering the secondary biological denitrification device is between 50% and 150%.
Optionally, the softening device comprises a softening reaction tank and a medicament feeding pump, the softening reaction tank is provided with a first water inlet, a second water inlet and a water outlet, the first water inlet is communicated with an original water tank for storing the stainless steel pickling wastewater, the second water inlet is communicated with the primary biological denitrification device through a return pipeline, the water outlet is communicated with the precipitation device, and the medicament feeding pump is used for feeding NaOH liquid medicament into the softening reaction tank to adjust the pH value of the softening reaction.
Optionally, the PH is between 9.0 and 9.5.
Optionally, the sedimentation device comprises a coagulation tank, a flocculation tank and a sedimentation tank which are communicated in sequence, a water inlet of the coagulation tank is communicated with a water outlet of the softening device, a water outlet of the sedimentation tank is communicated with a water inlet of the primary biological denitrification device, and the coagulation tank and the flocculation tank are respectively thrown intoAdding coagulant and flocculant to make CaCO produced by said softening reaction 3 And precipitating to form a compact floc, wherein the sedimentation tank is used for separating the compact floc and sending supernatant into the primary biological denitrification device.
Optionally, the coagulant is polyaluminium chloride, and the flocculant is anionic polyacrylamide.
Optionally, a carbon source is added into the inlet water of the primary biological denitrification device, wherein the carbon source is methanol, sodium acetate or glucose.
Optionally, the total nitrogen treatment load of the primary biological denitrification device is smaller than the total nitrogen treatment load of the secondary biological denitrification device.
Optionally, the first-stage biological denitrification device adopts an upflow anaerobic sludge bed reactor, and the second-stage biological denitrification device adopts a denitrification filter.
Optionally, the stainless steel pickling wastewater is obtained after neutralization, precipitation, fluorine removal and heavy metal ion removal.
The invention provides a denitrification treatment system for stainless steel pickling wastewater, which at least has one of the following beneficial effects:
1) The effluent of the denitrification liquid in a certain proportion in the effluent of the primary biological denitrification device flows back to the front end softening device, and the denitrification liquid is utilized
With Ca in the stainless steel pickling waste water 2+ Softening reaction is carried out, and Ca in the wastewater is greatly reduced 2+ And (4) concentration. Not only realizes the purpose of softening and removing hardness of the stainless steel pickling wastewater, but also solves the problem of high concentration Ca 2+ The problems of scaling of water pumps, pipelines and the inner wall of the tank body, reduction of activity of denitrifying microorganisms and the like caused by a rear-end treatment facility are solved, and no additional chemical agent is required to be added in the softening process, so that the consumption of wastewater treatment agents can be greatly reduced compared with the prior art;
2) Due to Ca in the inlet water 2+ The concentration is reduced, so that the biological denitrification device does not need to worry about CaCO 3 The scaling risk is separated out, so the method has the advantages of high treatment load, small occupied area, high effective sludge concentration, strong impact load resistance and the like;
3) The invention designs a two-stage series biological denitrification device, wherein the first-stage biological denitrification device runs under higher processing load, and the second-stage biological denitrification device runs under lower processing load, so that the floor area of processing facilities can be saved, and the stainless steel pickling wastewater can be effectively treated
The problem of large concentration fluctuation range ensures that the effluent quality is stable and reaches the standard;
4) After the stainless steel pickling wastewater is treated by the denitrification treatment system for the stainless steel pickling wastewater provided by the invention, ca in the water 2+ And
the concentration is greatly reduced, and the effluent quality can meet the discharge requirement and can be further desalted and recycled.
Drawings
It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. Wherein:
FIG. 1 is a schematic diagram of a denitrification treatment system for stainless steel pickling wastewater according to an embodiment of the invention.
In the drawings:
1-raw water tank; 2-softening the reaction tank; 3-a coagulating tank; 4-a flocculation tank; 5-a sedimentation tank; 6, an intermediate water tank; 7-a first-stage biological denitrification device; 8-water outlet tank; 9-secondary biological denitrification device.
Detailed Description
To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in simplified form and are not to scale, but are provided for the purpose of facilitating and clearly illustrating embodiments of the present invention. Further, the structures illustrated in the drawings are intended to be part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.
As used in this application, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this disclosure, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. As used in this disclosure, the term "plurality" is generally employed in its sense including "at least one" unless the content clearly dictates otherwise. As used herein, the term "at least two" is generally employed in a sense including "two or more" unless the content clearly dictates otherwise. Furthermore, the terms "first", "second", "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", "third" may explicitly or implicitly include one or at least two of the features.
Referring to fig. 1, fig. 1 is a schematic view of a denitrification system for stainless steel pickling wastewater according to an embodiment of the invention. The embodiment provides a denitrification treatment system for stainless steel pickling wastewater, which comprises a softening device, a precipitation device, a primary biological denitrification device 7 and a secondary biological denitrification device 9 which are communicated in sequence; wherein, the first and the second end of the pipe are connected with each other,
the softening device is communicated with the primary biological denitrification device 7 through a return pipeline to receive partial denitrification liquid produced by the primary biological denitrification device 7, and is used for enabling Ca in the stainless steel pickling wastewater to be softened 2+ With respect to the denitrification liquid
A softening reaction takes place to form CaCO 3 Precipitating;
the precipitation device is used for removing CaCO in the water discharged from the softening device 3 Precipitating;
the primary biological denitrification device 7 is used for discharging the sedimentation device into water
Reduction to N 2 Removing, wherein part of the denitrification liquid produced by the primary biological denitrification device 7 flows back to the softening device through the return pipeline, and the rest part of the denitrification liquid enters the secondary biological denitrification device 9;
the secondary biological denitrification device 9 is used for further removing the total nitrogen in the denitrification liquid.
The treatment object of the invention is stainless steel pickling wastewater after neutralization, precipitation, fluorine removal and heavy metal ion removal, and the stainless steel pickling wastewater contains Ca with higher concentration 2+ And
the invention uses the denitrification liquid in the denitrification liquid by refluxing the denitrification liquid effluent with a certain proportion in the effluent of the primary biological denitrification device 7 to the softening device at the front end
With Ca in the stainless steel pickling waste water 2+ Softening reaction is carried out, and Ca in the wastewater is greatly reduced 2+ And (4) concentration. Not only realizes the purpose of softening and hardness removal of the stainless steel pickling wastewater, but also solves the problem of high concentration Ca 2+ Scaling on water pumps, pipelines and the inner wall of a tank body caused by rear-end processing facilities, reduction of activity of denitrifying microorganisms and the like; and no chemical agent is required to be added in the softening process, so that the consumption of wastewater treatment agents can be greatly reduced compared with the prior art. In addition, the invention designs a two-stage denitrification device connected in series, which can effectively cope with the stainless steel pickling wastewater
The concentration fluctuation range is large, and the stable standard of the effluent quality is ensured.
Specifically, in this embodiment, part of the denitrification liquid produced by the primary biological denitrification device 7 is communicated withReflowing to the softening device through the backflow pipeline to perform softening reaction with the stainless steel pickling wastewater in the softening device so as to reduce Ca in the wastewater 2+ And (4) feeding the rest denitrification liquid into the secondary biological denitrification device 9 so as to further remove the total nitrogen in the denitrification liquid.
Preferably, the ratio of the flow rate of the denitrification liquid flowing back to the softening device to the flow rate of the denitrification liquid entering the secondary biological denitrification device 9 (referred to as reflux ratio) is between 50% and 150%.
Referring to fig. 1, the softening device includes a softening reaction tank 2 and a chemical feeding pump, the softening reaction tank 2 has a first water inlet, a second water inlet and a water outlet, the first water inlet is communicated with a raw water tank 1 for storing the stainless steel pickling wastewater, the second water inlet is communicated with the primary biological denitrification device 7 through the backflow pipeline, the water outlet is communicated with the precipitation device, and the chemical feeding pump is used for feeding NaOH liquid into the softening reaction tank 2 to adjust the pH of the softening reaction.
Preferably, the pH value is between 9.0 and 9.5.
Referring to fig. 1, the sedimentation device includes a coagulation tank 3, a flocculation tank 4 and a sedimentation tank 5 which are sequentially communicated, a water inlet of the coagulation tank 3 is communicated with a water outlet of the softening device, a water outlet of the sedimentation tank 5 is communicated with a water inlet of the first-stage biological denitrification device 7, and a coagulant and a flocculant are respectively added into the coagulation tank 3 and the flocculation tank 4, so that CaCO generated by the softening reaction 3 Deposit and form closely knit floc, sedimentation tank 5 be used for with closely knit floc separates out, 5 supernatants of sedimentation tank flow in middle water tank 6 to promote to one-level biological denitrification facility 7 through the pump.
In the embodiment, the coagulant is polyaluminium chloride (PAC), and the adding concentration is 50-150mg/L. The flocculant is anionic Polyacrylamide (PAM), and the adding concentration is 3-5mg/L.
In this embodiment, a carbon source is added to the water fed into the primary biological denitrification apparatus 7, and the carbon source is methanol, sodium acetate or glucose. The effluent of the primary biological denitrification device 7 flows into an effluent tank 8, part of the effluent tank 8 flows back to the softening reaction tank 2 through a reflux pump, and part of the effluent enters a secondary biological denitrification device 9 for treatment
The total nitrogen treatment load of the primary biological denitrification device 7 is smaller than that of the secondary biological denitrification device 9. In the embodiment, the primary biological denitrification device 7 is an upflow anaerobic sludge blanket reactor, and the total nitrogen treatment load is 0.6-1.0kgTN/m 3 D, operating temperature 20-35 ℃. The secondary biological denitrification device 9 is a denitrification filter, and the denitrification filter has the following process parameters: total nitrogen treatment load 0.1-0.4kgTN/m 3 D, the filtering speed is 0.5-2m/h, the particle size of a filter material is 3-5mm, and the filter material is preferably volcanic rock.
After being treated by the secondary biological denitrification device 9, the total nitrogen concentration in the wastewater is reduced to be below 5mg/L.
The following is illustrated by a specific example.
The hydrofluoric acid and nitric acid wastewater generated by a stainless steel factory is subjected to pH neutralization and lime precipitation defluorination treatment, and then is subjected to softening, hardness removal and biological denitrification treatment by adopting the stainless steel pickling wastewater denitrification treatment system. The quality of the treated influent water is shown in Table 1.
TABLE 1 stainless Steel Pickling waste Water quality
The whole system has the water treatment amount of 500L/d and continuously operates.
The stainless steel pickling wastewater flows into the softening reaction tank 2 from the raw water tank 1, is fully mixed with the refluxing denitrification liquid, and the Ca in the wastewater 2+ With in reflux liquid
The alkalinity carries out softening reaction to form CaCO 3 Insoluble matter was precipitated. The proportion of the reflux quantity of the denitrification liquid to the quantity of the wastewater to be treated is 50%150 percent. NaOH liquid medicine is added in the softening reaction process to adjust the pH value of the reaction to 9.0-9.5.
The effluent of the softening reaction tank 2 flows into the coagulation tank 3 and the flocculation tank 4 in sequence, and the coagulant and the flocculant are added to ensure that CaCO generated by the softening reaction 3 Insoluble material forms a dense floc which is then separated from the water in the settling tank 5. And the supernatant of the sedimentation tank 5 flows into the intermediate water tank 6 and is lifted to the primary biological denitrification device 7 through a pump. The coagulant is polyaluminium chloride, and the adding concentration is 100mg/L. The flocculating agent adopts anionic polyacrylamide, and the adding concentration is 4mg/L.
And adding methanol into the inlet water of the primary biological denitrification device 7 as an organic carbon source, so that the ratio of the concentration of COD to the concentration of TN in the water is 3.5-5. The first-stage biological denitrification device 7 adopts an upflow anaerobic sludge blanket reactor (UASB), and the upper part of the UASB is provided with a mud-water separation device. The total nitrogen treatment load of the primary biological denitrification device 7 is 0.8kgTN/m 3 D. The effluent of the primary biological denitrification device 7 flows into the water outlet tank 8, part of the effluent of the water outlet tank 8 flows back to the softening reaction tank 2 through a reflux pump, and part of the effluent enters the secondary biological denitrification device 9 for further denitrification treatment. The secondary biological denitrification device 9 adopts a denitrification filter. The denitrification filter tank process parameters are as follows: the total nitrogen treatment load was 0.2kgTN/m 3 D, the filtering speed is 1m/h, the particle size of a filter material is 3-5mm, and the filter material is preferably volcanic rock.
Adjusting the pH value of the softening reaction tank 2 to 9.0, and investigating the softening effect of different denitrification liquid reflux ratios.
TABLE 2 softening effect of different reflux ratios of the denitrified solution
As can be seen from the data in Table 2, the hardness of the effluent of the sedimentation tank 5 gradually decreases as the reflux ratio of the denitrification liquid increases. When the reflux ratio is increased from 100% to 150%, the reduction range of the hardness of the effluent is reduced. The reflux ratio is suitably 75 to 100 percent in consideration of the aspects of operation energy consumption and the like.
The reflux ratio of the stable denitrification liquid is 100 percent, and the softening effect of different reaction pH values is inspected.
TABLE 3 softening effect at different reaction pH values
As can be seen from the data in Table 3, the hardness of the effluent from the sedimentation basin 5 gradually decreases as the reaction pH increases. Particularly, when the reaction pH value is increased to be more than 9.0, the hardness of the effluent is obviously reduced. Considering that too high pH value has an influence on the operation of biological denitrification, the pH value of the softening reaction is preferably in the range of 9.0 to 9.5.
The TN concentrations of the inlet water and the outlet water of the two-stage biological denitrification device continuously operated for 30 days are shown in the following table 4, and the TN concentrations of the finally treated outlet water are all lower than 5mg/L. In addition, the TN concentration of the inlet water is greatly increased during the operation period, but the final treated outlet water quality is not influenced, so that the system for denitrifying the stainless steel pickling wastewater provided by the invention can effectively solve the problem that the quality fluctuation of the stainless steel pickling wastewater influences the biological denitrification effect.
TABLE 4 denitrifying Nitrogen removal Effect
In summary, the embodiment of the invention provides a stainless steel acid pickling wastewater denitrification treatment system, which is characterized in that a certain proportion of denitrification liquid effluent in effluent of a primary biological denitrification device flows back to a front end softening device, and denitrification liquid effluent in the denitrification liquid is utilized
With Ca in the stainless steel pickling waste water 2+ The softening reaction is carried out, and the reaction,greatly reduces Ca in the wastewater 2 + And (4) concentration. Not only realizes the purpose of softening and hardness removal of the stainless steel pickling wastewater, but also solves the problem of high concentration Ca 2+ The problems of scaling of water pumps, pipelines and inner walls of the tank body, reduction of activity of denitrifying microorganisms and the like caused by rear-end treatment facilities are solved, chemical agents do not need to be additionally added in the softening process, and compared with the prior art, the consumption of wastewater treatment agents can be greatly reduced. In addition, by designing a two-stage series biological denitrification device, the method can effectively deal with the stainless steel pickling wastewater
The concentration fluctuation range is large, and the stable standard of the effluent quality is ensured.
The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A stainless steel pickling wastewater denitrification treatment system is characterized by comprising a softening device, a precipitation device, a primary biological denitrification device and a secondary biological denitrification device which are communicated in sequence; wherein the content of the first and second substances,
the softening device is communicated with the primary biological denitrification device through a return pipeline to receive partial denitrification liquid produced by the primary biological denitrification device, and is used for enabling Ca in the stainless steel pickling wastewater to be softened 2+ With said denitrification liquid
A softening reaction takes place to form CaCO 3 Precipitating;
the precipitation device is used for removing CaCO in the water discharged from the softening device 3 Precipitating;
the first-stage biological denitrification deviceFor discharging said settling device into water
Reduction to N 2 Removing, wherein part of the denitrification liquid produced by the primary biological denitrification device flows back to the softening device through the return pipeline, and the rest part of the denitrification liquid enters the secondary biological denitrification device;
the secondary biological denitrification device is used for further removing the total nitrogen in the denitrification liquid.
2. The stainless steel pickling wastewater denitrification processing system of claim 1, wherein the ratio of the flow of denitrification liquid back to the softening apparatus to the flow of denitrification liquid entering the secondary biological denitrification apparatus is between 50% and 150%.
3. The denitrification treatment system for stainless steel pickling wastewater according to claim 1, wherein the softening device comprises a softening reaction tank and a chemical feeding pump, the softening reaction tank is provided with a first water inlet, a second water inlet and a water outlet, the first water inlet is communicated with a raw water tank for storing the stainless steel pickling wastewater, the second water inlet is communicated with the primary biological denitrification device through the return pipeline, the water outlet is communicated with the precipitation device, and the chemical feeding pump is used for feeding NaOH solution into the softening reaction tank to adjust the pH value of the softening reaction.
4. The denitrification system for stainless steel pickling wastewater of claim 3, wherein the pH is between 9.0 and 9.5.
5. The denitrification treatment system for wastewater from stainless steel pickling of claim 1, wherein the settling device comprises a coagulation tank, a flocculation tank and a settling tank which are sequentially communicated, wherein a water inlet of the coagulation tank is communicated with a water outlet of the softening device, and a water outlet of the settling tank is communicated with the primary raw water tankThe water inlets of the material denitrification devices are communicated, and a coagulant and a flocculant are respectively added into the coagulation tank and the flocculation tank so as to ensure that CaCO generated by the softening reaction 3 And precipitating to form a compact floc, wherein the sedimentation tank is used for separating the compact floc and sending supernatant into the primary biological denitrification device.
6. The stainless steel pickling wastewater denitrification processing system of claim 5, wherein the coagulant is polyaluminum chloride and the flocculant is anionic polyacrylamide.
7. The denitrification treatment system for wastewater from stainless steel pickling of claim 1, wherein a carbon source is added to the feed water of the primary biological denitrification apparatus, and the carbon source is methanol, sodium acetate or glucose.
8. The denitrification system for wastewater from stainless steel pickling of claim 1, wherein the total nitrogen treatment load of the primary biological denitrification apparatus is less than the total nitrogen treatment load of the secondary biological denitrification apparatus.
9. The stainless steel pickling wastewater denitrification processing system of claim 8, wherein the primary biological denitrification device is an upflow anaerobic sludge blanket reactor, and the secondary biological denitrification device is a denitrification filter.
10. The denitrification system for stainless steel pickling waste water according to claim 1, wherein the stainless steel pickling waste water is neutralized, precipitated, defluorinated, and heavy metal ions removed stainless steel pickling waste water.
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